www.elektor.com DECEMBER 2007 £3.80 electronics worldwide m ■ DJ) St Ci 3 » Experimenters' Kits: still around! and nicer than ever E ATmega Webserver reuse that ISA network card! Two-Way SPDIF/Toslink Digital Audio Converter Kit KC-5425 £7.25 + post and packing This kit converts coaxial digital audio signals into optical or vice-versa. Use this bit stream converter in situations where one piece of equipment has an optical audio input and the other a coaxial digital output. Kit includes Toslink optical modules, PCB with overlay, case with screen printed I lid, all electronic components and clear English instructions. Requires 9-12VDC wall adaptor (Maplin #UG01 B £1 3.99) DC Relay Switch KC-5434 £4.50 + post & packing An extremely useful and versatile kit that enables you to use a tiny trigger current - as low as 400pA at 12V to switch up to 30A at 50VDC. It has an isolated input, and is suitable for a variety of triggering options. The kit ^ includes PCB with /f * overlay and all electronic components with clear English instructions. Battery Zapper MKII KC-5427 £29.00 + post & packing This kit attacks a common cause of failure in wet lead acid cell batteries: sulphation. The circuit produces short bursts of high level energy to reverse the damaging sulphation effect. This new improved unit features a battery health checker with LED indicator, new circuit protection against badly sulphated batteries, test points for a DMM and connectton for a battery IR Romote Control Extender MKII KC-5432 £7.25 + post & packing Operate your DVD player or digital decoder using its remote control from another room. It picks up the signal from the remote control and sends it via a 2-wire cable to an infrared LED located close to the device. This improved model features fast data transfer, capable of transmitting Foxtel digital remote control signals using the Pace 400 series decoder. Kit supplied with case, screen printed front panel, PCB with overlay and all electronic components. Step Drill Bits TD-2436 £6.50 + post and packing TD-2438 £9.50 + post and packing Drill multiple size holes with the one bit. Ideal for plastics and soft metals such as aluminium or copper sheeting up to 4mm thick. Made from high speed steel. Two sizes available: 4 - 12mm in 1mm steps - TD-2436 12 - 20mm in 1mm steps - TD-2438 File Saw TH-2127 £3.95 + post and packing Perfect for cutting odd shaped holes in plastic pipes, plywood or other soft materials. It's not pretty, but it does the job. Requires 9VDC wall adaptor (Maplin #GS74R £10.99) KC-5419 £27.75 + post & packing A high energy 0.9ms spark burns fuel faster and more efficiently to give you more power! This versatile kit can be connected to conventional points, twin points or reluctor ignition systems. Kit supplied with diecast case, PCB and all electronic components. Budget 6" (150mm) Digital Vernier Calipers TD-2081 £5.75 + post and packing This carbon composite digital caliper is ideal for use where the cost of our precision stainless steel tool is not justified. The digital display is calibrated in imperial and metric units and a corresponding vernier scale is etched onto the caliper slide. Excellent value for money and tradesman tough. Looking for a particular KIT? Checkout Jaycar’s extensive range. We have kits and electronic projects for use in • Audio & Video • Car & Automotive • Computer • Learning & Educational / • Lighting • Power k • Test & Meters £ • General Electronics Projects -just for fun! Order Value Order Value £10 - £49.99 £5 £200 - £499.99 £30 £50 - £99.99 £10 £500+ £40 £100 - £199.99 £20 Max weight 121b (5kg). Heavier parcels POA. Minimum order £10. 6 in 1 Foldable Keyring Tool TH-1904 £1.50 + post and packing This handy tool is a wire cutter, standard pliers, crimping tool, wrench, and a .«£ Phillips and slotted screwdriver all in one! Folded up, it measures just 48 x 30mm. Lightweight and compact. A perfect ^ companion to your ^ keyring. Note: Products are despatched from Australia, so local customs duty and taxes may apply. How to order: Phone: Call Australian Eastern Standard Time Mon-Fri on 0800 032 7241 Email: techstore@jaycarelectronics.co.uk Post: PO BOX 6424, Silverwater NSW 1811. Australia Expect 10-14 days for air parcel delivery 430+ pages ALL prices in PDS ORDER ON-LINE ALL PRICING IN POUND STERLING MINIMUM ORDER ONLY £10 Universal High Energy Ignition Kit Build-Yourself Electronic Project Kits Post and Packing Charges Check out the Jaycar range in your FREE Catalogue - logon to www.jaycarelectronics.co.uk/elektor or check out the range at www.jaycarelectronics.co.uk (Monday - Friday 09.00 to 17.30 GMT + 10 hours only) For those who want to write: 100 Silverwater Rd Silverwater NSW 2128 Sydney AUSTRALIA Bi+Scope USB Mixed Signal Oscilloscope Analog Digital Digital Storage Oscilloscope Dual Channel Digital Scope with industry standard probes or POD connected analog inputs. Fully opto-isolated. Mixed Signal Oscilloscope Capture and display analog and logic signals together with sophisticated cross-triggers for precise analog/logic timing. Multi-Band Spectrum Analyzer Display analog waveforms and their spectra simultaneously. Base-band or RF displays with variable bandwidth control. Multi-Channel Logic Analyzer Eight logic/trigger channels with event capture to 25nS. DSP Waveform Generator Built-in flash programmable DSP based function generator. Operates concurrently with waveform and logic capture. Mixed Signal Data Recorder Record to disk anything BitScope can capture. Supports on-screen waveform replay and export. User Programmable Tools and Drivers Use supplied drivers and interfaces to build custom test and measurement and data acquisition solutions. Inventing the future requires a lot of test gear... s ' ...or a BitScope dljQ * I t BS100U Mixed Signal Storage Scope & Analyzer Innovations in modern electronics engineering are leading the new wave of inventions that promise clean and energy efficient technologies that will change the way we live. It's a sophisticated world mixing digital logic, complex analog signals and high speed events. To make sense of it all you need to see exactly what's going on in real-time. BS100U combines analog and digital capture and analysis in one cost effective test and measurement package to give you the tools you need to navigate this exciting new frontier. ftfScop* a o BitSc&pe D Standard 1M/20pF BNC inputs Smart POD Connector Opto-isolated USB 2.0 12VDC with low power modes BitScope DSO Software for Windows and Linux BS100U includes BitScope DSO the fast and intuitive multichannel test and measurement software for your PC or notebook. Capture deep buffer one-shots, display waveforms and spectra real-time or capture mixed signal data to disk. Comprehensive integration means you can view analog and logic signals in many different ways all at the click of a button. The software may also be used stand-alone to share data with colleagues, students or customers. Waveforms may be exported as portable image files or live captures replayed on another PC as if a BS100U was locally connected. www. bitscope .com 12/2007 - elektor 3 Call for papers One of the most frequent questions I get, usually by email but occasionally by telephone or letter (!) is "can I con- tribute to your wonderful publication and if so, what are the requirements and the specific subjects you are inte- rested in?" The answer is invariably, "Yes, please, we're ready to evaluate the publication value of your article proposal Please review the Author Guidelines [1] document available under the Service tab on our website at www.elektor.com". To this I usually add a few encouraging words and a pointer to Elektor's Publishing Plan [2] for the current year. Now if this sounds like a straightforward ap- proach to you, you should know that some of our competitors simply do not accept articles from persons outside their circle of 'approved authors' nor arrange for theme-driven content of their publications. This year, in addition to the broad terms used in the Publishing Plan for the 1 2 months ahead of us in 2008, we have ventured to add a third column listing some keywords that hopefully trigger a response from you. For example, for the June 2008 issue focusing on Cool Electronics, why not send us your contribution on PC coo- ling, smart heatsinks, or electronics in clothes to keep you cool? Contributi- ons from companies, journalists and workers in the industry are also wel- comed. Although the 2008 schedule has been online for just two weeks now, the approach seems to work — three major articles are already in stock for publishing. Now, for the solemn bit: about 70 percent of the article proposals reaching us through all international channels sadly gets rejected for publication. The reasons for the team of editors and designers be so harsh and unkind to budding authors in- clude uninventive use of components; the use of obsolete components; re- hashing manufacturer's datasheets or old Elektor articles (!); vague circuits nicked from websites, poor electronic design and attempts to use the maga- zine as a catalogue for their products. The rest is gladly considered for publication and/or post-engineering by our lab, no matter if the piece is poorly written or the prototype built on perfboard — in general we are good humoured with a keen eye for originality. Even if it takes a while for us to get back to you due to the work load here at Elektor House, give us a try and eventually see your name (and circuit!) in print — it's by no means difficult, we're here to help. Jan Buiting, Editor lekvo r electronics worldwide M®w 7 &MH? Saitofc Here we present the control electronics for a do-it-yourself SMD oven. It is even available as a kit of parts, making the construction easy provided you know your bit about elec- trical safety regulati- ons. In good Elektor tradition, in an associated article (starting on page 20) we supply a series of useful tips for the practical use of a reflow oven. 24 AVR Webserver In the world of Open Source technology seemingly nothing is impossible. What's more, it's entirely feasible to cram the code for a Webserver into an ATmega32 microcontroller. External control and connectivity for a webcam make this project even more attractive. j f [1] www.elektor.com/author_guide [2] www.elektor.com/publishing_plan CONTENTS Volume 33 December 2007 372 What could be nicer for an electro- nics enthusiast than to help his or her children take their first steps into the world of electronics? Electronics lab kits let children of all ages experiment with electronics to their heart's content. starts on page 45 r Merry Christmas and a happy, 1 L peaceful 2008 from all at Elektor! J| 70 Micromechanical Silicon Gyroscopes In technological terms the progress being made in micromechanical sensors is enormous. Particularly commercially interesting examples of this are acce- lerometers and rotation sensors, also called gyroscopes. As manufacturing prices inexorably fall, so the number of applications rises. Stefan Tauschek reports. projects 16 Reflow Solder Controller 24 AVR Webserver 30 VR Stamp™ Toolkit 34 Craft Drill Controller 76 E-blocks DCF Clock 84 Power on Tap 92 LED's Dive! Design Tips: a Mini Dl 96 LED Brake/Rear Light technology Reflow Techniques Micromechanical Silicon Gyroscopes 98 IC-free (almost) info & market 6 Colophon 8 Mailbox News & New Products 41 Learn Young... 8 < i.MX21 ARM9 Linux Board (review) 10* Elektor SHOP 08 Sneak Preview infotainment 80 A Radiant Future 100 Hexadoku 101 Retronics: Philips 'SXA' VHF/UHF Handheld (1 977) ELECTRONICS WORLDWIDE elektor international media Elektor International Media provides a multimedia and interactive platform for everyone interested in electronics. From professionals passionate about their work to enthusiasts with professional ambitions. From beginner to diehard, from student to lecturer. Information, education, inspiration and entertainment. Analogue and digital; practical and theoretical; software and hardware. iioriics 1 PI I H H 1 ii mkt p n 1 1 U \ j ■ ^ i j 1- / • / ^ 3 V - o — — 1 .It* R ™ *"" ■ 111 J : / 7 > .M m Volume 33, Number 372, December 2007 ISSN 0268/4519 Elektor Electronics aims at inspiring people to master electronics at any personal level by presenting construction projects and spotting developments in electronics and information technology. Publishers: Elektor International Media, Regus Brentford, 1000 Great West Road, Brentford TW8 9HH, England. Tel. (+44) 208 261 4509, fax: (+44) 208 261 4447 www.elektor.com The magazine is available from newsagents, bookshops and electronics retail outlets, or on subscription. Elektor is published 1 1 times a year with a double issue for July & August. Elektor is also published in French, Spanish, German and Dutch. Together with franchised editions the magazine is on circulation in more than 50 countries. International Editor: Wisse Hettinga (w.hettinga@elektor.nl) Editor: Jan Buiting (editor@elektor.com) International editorial staff: Harry Baggen, Thijs Beckers, Ernst Krempelsauer, Jens Nickel, Guy Raedersdorf. Design stc Antoine Authier, Ton Giesberts, Paul Goossens, Luc Lemmens, Jan Visser, Christian Vossen Editorial secretariat: Hedwig Hennekens (secretariaat@elektor.nl) Graphic design / DT Giel Dols, Mart Schroijen Managing Director / Publisher: Paul Snakkers Marketing: Carlo van Nistelrooy Customer Services: Anouska van Ginkel Subscriptions: Elektor International Media, Regus Brentford, 1000 Great West Road, Brentford TW8 9HH, England. Tel. (+44) 208 261 4509, fax: (+44) 208 261 4447 Internet: www.elektor.com 6 elektor - 12/2007 J A complete solution: robot + software + curriculum Line following and maze solving High-tech specifications Also programmable with C or ASM E-blocks compatible Motivating for education and hobby lektor SHOP Order quickly and safe through WWW.elektor.com/shop or use the Order Form near the end of the magazine Email: subscriptions@elektor.com Rates and terms are given on the Subscription Order Form Head Office: Elektor International Media b.v. P.0. Box 1 1 NL-61 1 4-ZG Susteren The Netherlands Telephone: (+31 ) 46 4389444, Fax: (+31 ) 46 43701 61 Distribution: Seymour, 2 East Poultry Street, London EC1A, England Telephone:+44 207 429 4073 UK Advertising Huson International Media, Cambridge House, Gogmore Lone, Chertsey, Surrey KT1 6 9AP, England. Telephone: +44 1932 564999, Fax: +44 1932 564998 Email: p.brady@husonmedia.com Internet: www.husonmedia.com Advertising rates and terms available on request. International Advertising Frank van de Raadt, address as Head Office Email: advertenties@elektor.nl Advertising rates and terms available on request. Copyright Notice The circuits described in this magazine are for domestic use only. All drawings, photographs, printed circuit board layouts, programmed integrated circuits, disks, CD-ROMs, software carri- ers and article texts published in our books and magazines (other than third-party advertise- ments) are copyright Segment, b.v. and may not be reproduced or transmitted in any form or by any means, including photocopying, scanning an recording, in whole or in part without prior written permission from the Publishers. Such written permission must also be obtained before any part of this publication is stored in a retrieval system of any nature. Patent protec- tion may exist in respect of circuits, devices, components etc. described in this magazine. The Publisher does not accept responsibility for failing to identify such patent(s) or other protection. The submission of designs or articles implies permission to the Publishers to alter the text and design, and to use the contents in other Segment publications and activities. The Publishers cannot guarantee to return any material submitted to them. Disclaimer Prices and descriptions of publication-related items subject to change. Errors and omissions excluded. © Elektor International Media B.V. 2007 Printed in the Netherlands 12/2007 - elektor 7 INFO & MARKT MAILBOX Classy Class-A Amp Dear Jan — I thought I would drop you a line to say I have recently finished building your design for a valve amplifier published in the June 2007 issue. I built my amp using an upside down oven roasting dish, this may sound strange but these trays are great as they are quite strong and most have a Teflon coating which saves painting. I also wound my own E.l transformers from your specs as I have the equipment to do so. Thanks for the design, it works very well, sounds great and manages to achieve the figures you quoted for it. I sometimes build designs from the net but sad to say some don't live up to expectations. I find that designs in well known magazines are researched well and work well. I do however have a couple of minor criticisms — pin numbers for V2.B are incorrect and C 7 is the wrong way around. One again, thanks for the circuit and I'll keep checking for future designs. Keith Columbine (Australia) Thanks for that Keith , somehow we knew the design of the valve omp was a dead cert because the author came to our audio lob and gave o very convincing demonstration of his own unit. The amp was not only pictured for the article , but also \ grilled ' for an hour or so by our engineers to verify its performance. No smoke , no burnt crusts or fingers , just lovely 'tube sound' when playing our test CDs. Well recommended \ that one. The corrections you mention were published on the project page found our website. Nice reminiscences Dear Sirs — it was nice to read a little history about Elektor in the October 2007 issue. I have been in the electro-mechanical industry for some 47 years now, we have all seen a lot of changes in the way our hobby has grown. I must admit that at times I seemed baffled and came up against a hard wall with some projects. Maybe this is all part of growing older. But I still get a lot of pleasure from this hobby, even if it is only in reading matter. Up until the year 2000, I had every copy of your magazine, they were all neatly filed and stored. Alas, I re-married and lost my storage space and had to part with 99% of them, I think I understand my wife when she says "you can't keep them up to date all the time". On a different note, I would like to see an arti- cle on the storage of data from an Oregon Scientific WMR926NX Weather station. In other words 'an SD card and interface' that can be downloaded to the PC in my time instead of real time, this would save on energy! All the best for the future. Alan Pattison (UK) That's such nice things you wrote there , A/an, / may wont to pub- lish it in Mailbox , December 2007. (there, I did it! I hove passed your design re- quest to our lab and a number of freelance contributors. CR2032 and musical tea lights Dear Jan — I noticed the other day that the CMOS battery of one of my PCs was dead. You've probably seen the familiar start-up message, 'CMOS checksum error, de- faults loaded'. It turned out to be a 3.3-V lithium battery, type CR2032, which is used not only on PC motherboards but also in all sorts of other equip- ment, such as home automa- tion remote-control units, heart rate monitors, and so on. As this type of battery from a top-name manufacturer can easily set you back several euros, I decided to look for a cheaper alternative. I remem- bered that I had seen an advert from a major discounter for 'electronic tea lights' that were powered by a button cell that appeared to be very close to the size and shape of the CR2032. You've probably seen tea light of this sort, with a tea-warmer candle where the wick has been replaced by a flickering yellow LED in a flame-shaped housing. After ploughing through the weekly stack of junk mail in my letterbox, I indeed found an advert for 'electronic tea lights, battery included, 2 for 75p'. In the shop I discovered that I was in luck: the batteries were type C2032. Although they were probably not top-brand batteries, I could hardly com- plain about the price, and I picked up a sizeable quantity. Now my motherboard and other household devices are assured of a source of power for a long time (or at least I hope so). But that's not the end of the story. After all, I had a nice pile of electronic tea lights, and with my natural curiosity I had to take a closer look at them. After opening up one of them, I found that the flickering light effect was produced by an 1C embedded in a drop of hard plastic. At first I thought it was a random-number generator, but after watching for a while I discovered a certain repetitive pattern in the flickering. Then I wondered how it would sound if I connected it to a speaker. I quickly got out my soldering iron, soldered a short length of cable to the pins of the LED, and connected the other end of the cable to my audio system. To my utter amaze- ment, the tea light was playing 'Happy Birthday'! The chip in the tea light is obviously the same kind you find in musical greeting cards. Using a phototransistor and the amplifier from a portable FM scanner, I quickly put together a tea light music de- tector. It turned out that slightly more than half of the tea lights played 'Happy Birthday', while the rest played a melody that I didn't recognise. There is thus some variation in them. Now we have a new subject of conversation for birthday get-togethers: 'What tunes do your tea lights play?' Martien Jansen (Netherlands) Software for SDR receiver Dear Editor — in response to your SDR receiver article in the May 2007 issue, I bought the fully assembled board. 8 elektor - 12/2007 However, the software you offer did not meet my wishes. I preferred the WinRad program from Alberto (I2PHD), although it did not have an interface to your SDR receiver, but it does have a well-documented API that can be used to produce a suitable interface. Armed with the WinRad, FTDI and Cypress data sheets and APIs, I went to work and generated an interface DLL for linking your SDR receiver to WinRad. The initial version of this library can be found on my website at http://home. gjk4all.net/winrad-dll/. The source code for the DLL can also be downloaded from this site. I have placed the code under the GPL licence to prevent commercial exploitation. I am sending you this mes- sage because I would like to make your readers aware of WinRad and because I think that using this package increases the versatility of your receiver. I thus hope that you will inform your readers that your SDR receiver can be linked to WinRad. Gert Jan Kruizinga (Netherlands) This is without question interes- ting information for other rea- ders, and it certainly deserves a place in our Mailbox forum! Audio test CDs Dear Jan — I am looking for a test CD (or a copy of one) with third-octave noise tracks so I can make some quick tests on loudspeakers without using a PC. A few years ago, you could get CDs of this sort from Stax (among others), but they are no longer available because all test programs nowadays work with PC sound cards. However, I'm sure that loud- speaker hobbyists must have various CDs of this sort tucked away in a drawer somewhere. Who can help me out? Jocelyn Hayes (UK) We managed to find two CDs. You can still order test CDs from http://www.rainfall.com/ cdroms/pink_noise.htm and http://www. rivesaudio. com/ software/TestCD.html. There is almost certainly software availa- ble that can generate the signals you need, but it probably costs more than the test CDs. Replacement LED driver PCB Dear Elektor people — the replacement for the defective LED driver board attached to the September issue arrived in good order, thanks for that. I immediately connected two white LEDs to it, along with a 1 .5-V microcell that had just been removed from some other equipment, and the LEDs are still lit up on the second day now. Thanks once again for your trouble. Ruprecht Hayna As already reported on our fo- rum, we have sent new LED dri- ver boards at no charge in ca- ses where the boards included with the September 2007 issue did not operate properly due to damage in transport. We would like to once again state that the inductors were delivered in per- fect condition from the manufac- turer (Wurth-Electronics) and that the assembly work performed by ECS was also free of errors. The damage that occurred is enti- rely due to severe mechanical stresses (pressure and impact loads) during distribution of the magazine. Calibration tip for Coil Clinic When I tried to calibrate the Coil Clinic inductance meter published in the June 2007 issue of Elektor with the speci- fied 22 |jH and 220 nH coils, an 'Out of range' message was always displayed with the 220 nH coil. There were no problems with the 22 |jH coil. The values of the refer- ence coils that I used were measured with an accuracy of 1% using an HP LCR meter. All coils with a value of 1 80 nH or less yielded a 'No value' message (no oscillation). The calibration process worked perfectly after I replaced C6 and C7 with high-quality SMD capacitors. Now the measuring range extends down to slightly less than 1 00 nH. The value of C6 is definitely 4.7 nF, as indicated on the schematic dia- gram, since the combination of 100 nH and 4.7 nF yields a resonant frequency of about 7.3 MHz. The value of C6 is stated incorrectly as 4.7 |jF in the components list. The displayed value is very stable now. The meter ran all night with a 220-nH calibra- tion inductor, and the next morning it still displayed exactly 220 nH. Norbert Kohns, DG1KPN Thank you for your tip, which will be very helpful in case anyo- ne else has a quality problem with C6 and C7. Fortunately, the components list error is 'harm- less' because the value shown on the schematic diagram is correct and there is simply not enough room on the PCB for an electrolytic capacitor in the C6 position. A glance at the photo of the prototype board (Figure 3 in the article) should eliminate any doubt. Mai I Box Terms • Publication of reader's orrespondence is at the discretion of the Editor. • Viewpoints expressed by correspondents are not necessarily those of the Editor or Publisher. • Correspondence may be translated or edited for length, clarity and style. • When replying to Mailbox correspondence, please quote Issue number. • Please send your MailBox correspondence to: editor@elektor.com or Elektor, The Editor, 1 000 Great West Road, Brentford TW8 9HH, England. 12/2007 - elektor 9 INFO & MARKET NEWS & NEW PRODUCTS 1,000 Lumens from a single LED Cree, Inc. announced it has de- monstrated light output of more than 1 ,000 I umens - an amount equivalent to the output level of a standard household light bulb - from a single R&D LED. Cree's achievement demonstrates continu- ed leadership in the development of LEDs that can make traditional light bulbs obsolete. A single-die LED, driven at 4 amps, produced 1,050 lumens in cool white and 760 lumens in a warm-white version. Efficacy of the cool-white LED was 72 lumens per watt and 52 lumens per watt from the warm-white device. Both LED versions operated at substan- tially higher efficacy levels than those of today's conventional light bulbs. Historically, Cree's R&D de- monstrations generally have been commercialized within 1 2 to 24 months. Cree's product families include blue and green LED chips, lighting LEDs, LEDs for backlighting, pow- er-switching devices and radio-fre- quency/wireless devices. www.cree.com (070723-VII) USB-to-Ethernet device server for synchronised audio/video Data transfer Lantronix, Inc. announced their UBox® 2100, the first USB-to- Ethernet device server to support the USB isochronous data transfer standard, typically used for au- dio and video applications. With UBox 2 1 00, users can put virtually any off-the-shelf USB 2.0 peripher- al device on an Ethernet network. Removing the distance limitations normally associated with USB, us- ers can access and share a vari- ety of devices such as web cams, speakers, microphones, sensors, security access equipment, multi- function printers, hard drives, scan- ners - even Apple® iPods® - over the Internet. Isochronous data transfer is typical- ly used for time-dependent applica- tions, such as multimedia streams with synchronised audio and video where the data must be delivered within specific time constraints. Along with its support for isochro- for other users. Flexible network configuration op- tions make it easy to use the UBox in local area networks (LANs) or wide area networks (WANs). Rather than require administrators to install drivers on each computer when each UBox is added, its Ac- tive Discovery feature automatical- ly loads the software on each com- puter so that networked USB devic- es are available for immediate use over a LAN. For WANs, adminis- trators can set up passwords and use static IP addresses to connect UBoxes to the network. UBox 2100 supports USB 2.0 high-speed and is housed in a rug- gedised metal enclosure. It will be available globally through Lantro- nix channel and other sales part- ners for $154 US MSRP. www.lantronix.com (070723-V) nous data transfer, UBox elimi- nates the need to directly connect devices to a PC, thus IP-enabling the USB devices. For exam- ple, users can ac- cess and ware is installed and the UBox is configured, it runs seamlessly in the background allowing USB equip- ment to be automatically connected to PCs in the same manner as if they were connected locally. share web cams with fully synchronised au- dio/ video in real-time over a net- work or the Internet without need- ing to connect them directly to a computer. UBox includes software designed to identify, access, configure, upgrade and secure each UBox unit on the network as needed. Once the soft- UBox 2 1 00 includes an Auto-Connect feature that automatically connects and disconnects shared USB print- ers based on need. UBox enables a PC to connect to the printer when it needs to print, then au- tomatically disconnects when the job is finished, freeing the printer Nepcon UK celebrates 40 th anniversary with additional exhibitor benefits for 2008 event In 2008 Nepcon, the complete electronics production line event ebrate 40 years as the flagship event of the electronics community. As preparations for the 2008 show gain momen- tum, the Nep- co n team announces significant additional benefits for exhibitors to celebrate this milestone event. These ben- efits are be- ing offered following ex- tensive discussions with customers and negotiations with the NEC. As a result exhibitors from last year's event can save money by taking advantage of 'priority booking', with prices held at the 2007 rate until the 31st October. Free lifting and storage will be available to all exhibitors, helping to reduce costs and post-show invoices and there will be a 10% reduction on 2007 prices for service charges on electricity, air and water — mak- ing the running of machinery more cost effective. In 2008, exhibitors will also benefit from a three day build period, making it easier for companies with large equipment to set-up and avoiding expensive Sunday freight deliveries. Furthermore, the Nepcon team is delighted to announce that fol- lowing negotiations with the NEC there will no longer be an £ 8.00 parking fee, making parking free for all who attend Nepcon 2008. For further details on exhibiting call Louise Conway on (+44) (0)20 8910 7706 or email lynda@con- sortiopr.co.uk. www.nepcon.co.uk www.consortiopr.co.uk (070819-IV) 10 elektor - 12/2007 FMicro NTC Thermistor Sensors for catheter/medical Applications SeMitec's newest product is a mi- cro thermistor sensor designed primarily for use in medical applications. Using FT thin-film technology com- bined with laser-trimming tech- niques, the Fmicro thermistor sensor is only 0.5 mm diameter by 2.3 mm long. The Fmicro is based on one of SeMitec's small- est FT thermistors encapsulated in a polyamide tube and fitted with 38AWG insulated leads. The Fmicro is accurate to ±0.2 K at 37 °C and is small enough to be incorporated within a catheter probe for internal body tempera- ture measurement. The operat- ing temperature range is -10 to +70 °C. www.atcsemitec.co.uk (070819-III) lektor electronics worldwide Flowcode for Atmel AVR micros mnra/x Those of you who have been follow- ing the evolution of Flowcode and E-blocks will be aware that all of this technology is based only on the 1 6 and 1 8 series of PICmicro microcon- trollers. Not any more! Now there is a new version of Flowcode which generates code for the popular At- mel AVR series of microcontrollers. The new version of Flowcode works with the Atmega and Attiny range of chips. Here's a list of the chips that are supported: ATmegal6, ATmega324P, AT- mega8515, ATtiny24, ATtiny45, ATmegal62 / ATmega328P / AT- mega8535, ATtiny25, ATtiny461, ATmegal64P, ATmega48 / AT- mega88, ATtiny26, ATtiny84, ATmegal68, ATmega644, AT- tinyl 3, ATtiny261 , ATtiny85, AT- mega32, ATmega8, ATtiny2313 / ATtiny44, ATtiny861 The support for AVR is complete: • All of Flowcode's internal com- ponents like LCD, CAN bus, inter- net, IrDA etc. are supported, and all of the E-blocks 'downstream' boards are compatible with the Flowcode routines. • You can use the new version of Flowcode with any AVR program- ming hardware or you can deve- lop systems based on the E-blocks AVR multiprogrammer. • Flowcode supports on-screen simulation of systems based on the Atmel AVR processor as you can see in the screen image on the right. • Any programs you have written for the PICmicro microcontroller using Flowcode will also transfer to the AVR microcontroller with ease. As a special opening offer to Elek- tor's AVR orientated readers we are making a bundle of Flowcode for AVR Professional and a selec- tion of E-blocks available at a dis- count of 30% off the retail price. Further details in the E-blocks sec- tion at www.elektor.com / shop (070819-11) PICmicro and PIC are trademarks of Microchip Technology Inc. ECio and [■blocks are trademarks of Matrix Multimedia Limited. 32-Channel, 1-GHz Logic Analyser The LA-Gold-36 now in stock at The Debug Store is a high perfor- mance logic analyser with an in- tegrated pattern generator. It was designed to be of superior techni- cal quality to ensure measurements of excellent signal integrity. With class-leading specifications, it of- fers a comprehensive digital de- bugging environment for the elec- tronics professional. The LA-Gold-36 has a large data buffer of 1 megasamples per channel for sampling rates of up to 1 GHz on all 32 channels. The large buffer allows long capture times at high sampling rates. The digital logger function is for captur- ing very slow varying signals, e.g. room temperature. The LA-Gold-36's integrated pat- tern generator can be used in conjunction with the logic analy- ser. The user can set up the instru- ment to output data to the unit un- der test (UUT) with the pattern generator and then measure its response with the logic analyser. The LA-Gold-36 connects to the PC via USB2.0 for rapid display updates. (070819-VI) www.TheDebugStore.com 12/2007 - elektor 11 INFO & MARKET NEWS & NEW PRODUCTS Low-cost Zigbee Antennas strength, the slightly longer CTI-RA CTi Ltd. launched two new series of low-cost ZigBee antennas which provide designers with a wide choice of configuration options. Both series of antennas are suitable for use with any IEEE 802.15.4 standard 2.4-GHz ZigBee wireless system, and can accommodate ver- tically and horizontally polarised signals. Typical ZigBee wireless applications include environmental monitoring and control in homes and buildings, and low-speed data acquisition from remote sensors in industrial process control systems. The CTI-SB series of stubby Zig- Bee antennas comprises three mo- dels, with a choice of straight and right-angle SMA male and SMA male RS connectors. For applica- tions that demand increased signal series of rubber ZigBee antennas provide a gain of up to 9 dBi. These antennas employ co-linear elements (contained within a ro- bust, semi-flexible rubber housing) to maximise RF efficiency, and fea- ture an integral swivel joint to facil- itate orientation. The CTI-RA series offers a choice of SMA male RS and TNC male RS connectors. For designers of ZigBee systems intended for operation in the 868 MHz European or 9 1 5 MHz Ame- rican ISM bands, CTi has a large selection of embedded and peri- pheral GSM antennas that operate at these frequencies. The compa- Non-volatile Digital Potentiometers With SPI Interface Microchip announces the MCP4141/2 and MCP4241/2 non-volatile digital potentiome- ters. The new 7- and 8-bit devic- es have an SPI interface and are specified over an extended tem- perature range of -40 to +125 degrees Celsius. Unlike mechanical potentiometers, the MCP41XX/42XX devices can be controlled digitally, via an SPI interface. This can increase system accuracy, flexibility and manufac- turing throughput, while decrea- sing manufacturing costs. Non-vo- latile memory enables the devices to retain their settings at power down, and their low static current consumption of just 5 pA maximum helps to extend battery life. The MCP41XX/42XX digital potentio- of trimming, calibration, set-point, meters are ideal for a wide range offset-adjust, signal conditioning Lowest-Cost USB Data Acquisition devices from Nl Scientists, technicians, engineers and students can now take advan- tage of measurement-quality data acquisition and the convenience of USB plug-and-play technology at a lower cost with the new Na- tional Instruments USB-6008 and USB-6009 data acquisition (DAQ) devices. Starting at just £95 or €145 the new USB DAQ devices offer small size and easy connectivity, making them ideal for operations such as data logging and environmental monitoring. They also are useful in academic settings and are in- expensive enough for students to purchase and use in lab experi- ments. Both devices ship with free, ready-to-run data-logging softwa- re that engineers and students can use to begin taking measurements within minutes. The Nl USB-6008 and Nl USB- 6009 DAQ devices deliver mul- tifunction capabilities with eight channels of 1 2- or 1 4-bit analogue input, two analogue outputs, 12 digital I/O lines and one counter. Both devices draw power from the USB bus, so they do not require an external power supply to operate. They include removable screw ter- minals for direct signal connectiv- ity, an onboard voltage reference for powering external devices and sensors, a four-layer board design for reduced noise and improved accuracy and overvoltage protec- tion on analogue input lines up to ±35 V. In addition to ready-to- run data-logging software, each device includes NI-DAQmx Base measurement services driver soft- ware for programming the device in LabVIEW orC. Elektor readers can learn more about the new USB products as well as a full range of M Series multifunction DAQ devices, at the website below. www.ni.com/daq (070819-VII) ny also offers a range of adaptor cables which simplify system inte- gration significantly; they are par- ticularly useful for connecting the type of sub-miniature U.FL or W.FL connectors commonly used on pre- assembled ZigBee modules to ex- ternal antenna. All CTi ZigBee antennas feature high-quality gold-plated connector pins to ensure signal integrity, have a nominal 50 ohms output imped- ance, and exhibit an output VSWR (Voltage Standing Wave Ratio) of less than 2:1 . www.cti-int.com (070819-V) and control applications. The MCP4141/2 digital poten- tiometers are available in 8-pin SOIC, MS OP, PDIP and 3x3 mm DFN packages. The MCP4241 is available in 14-pin SOIC, PDIP and TSSOP packages, and a 10- pin 4 mm x 4 mm QFN package. The MCP4242 is available in a 10-pin MSOP and an 8-pin 3x3 mm DFN package Samples of all the new devices are available from sample.microchip.com while pro- duction quantities can be ordered at www.microchipdirect.com. www.microchip.com /MCP4 1 XX www.microchip.com/MCP42XX (070819-VIII) 12 elektor - 12/2007 Designing Embedded Systems with PIG I I ci h + Elsevier Ltd. has a wide range of books of interest to electronics engi- neers, designers and enthusiasts, particularly those into PIC software development. A selection of relevant new releases is listed here along with their ISBN codes. Audio Power Amplifier Design Handbook (9780750680721) Designing Embedded Systems with PIC Microcontrollers (9780750667555) Essential Matlab for Engineers and Scientists (9780750684170) Interfacing PIC Microcontrollers (9780750680288) Linux for Embedded and Real-time Application (9780750679329) PIC Basic Projects (9780750668798) PIC in Practice (9780750668262) Practical Electronics Handbook (9780750680714) Practical RF Handbook (9780750680394) Robot Builders Cookbook (9780750665568) (070819-1) Aiiijin hiiirr Amplifier W Boards for PIC, ARM and Embedded Linux SK Pang Electronics announcxe three newe products. The SB- C65EC is an embedded (PIC based) Single Board Computer with 10 Mbs Ethernet and RS232 interface. It can be added to any 10/100Mbs Ethernet network. It is programmed with a bootloader and a free SBC65EC Web Server. Configuration, control and monitor- ing can be done via a web based interface, HTTP CGI commands or UDP commands. It has 32 general purpose I/O ports, of which 12 are 10-bit ADC (analog to digi- tal) inputs, and 4 are 10-bit PWM (Pulse Width Modulator) outputs. The FOXLX32 is a complete Linux system in just 66 x 72 mm. The Fox board runs a real Linux oper- ating system (not a uC Linux) on an ETRAX 100LX microproces- sor, a 100 MIPS RISC CPU made by Axis. The FOX Board has two main field applications: as a stand alone device to build a micro web server or other network devices as proxy, router, firewall, etc. As a core engine to plug onto the PCB of a user application board instead of a simple microcontroller. For ARM7 development systems, there's a range of Atmel's SAM7 and NXP's LPC microcontroller boards. These feature from 32 kbyte to 2 Mbyte flash and from 8 kbyte to 1 Mbyte SRAM. All boards are compatible with the ARM-USB-TINY JTAG programmer making them ideal for prototype development and educational use. www.skpang.co.uk (0708 19-X) 12/2007 - elektor 13 mikroElektronika DEVELOPMENT TOOLS | COMPILERS | BOOKS PICFIash rruKrtflCQ Wufipart r.L PICFIash programmer - an ultra fast USB 2.0 programmer for the PIC microcontrollers. Continuing its tradition as one of the fastest PIC programmer on the market, a new PICFIash with the mikrolCD now sup- ports more PIC MCUs giving developer a wider choice of PIC MCU for further prototype development. mikrolCD debugger enables you to execute mikroC / mikroPascal / mikroBasic pro- grams on the host PIC micro- controller and view variable val- ues, Special Function Regi- sters (SFR), memory and EEP- ROM while the program is run- ning. LvPIC Flash Wien mlisr^lCP support m LvPICFIash programmer - an ultra fast USB 2.0 program- mer for the PIC24 / dsPIC33 MCUs. A new LvPICFIash with the mikrolCD now supports more MCUs giving developer a wider choice of PIC24 / dsPIC33 MCU for further proto- type development. mikrolCD debugger enables you to execute mikroC / mikroPascal / mikroBasic pro- grams on the host PIC24 / dsPIC33 microcontroller and view variable values, Special Function Registers (SFR), memory and EEPROM while the program is running. dsPICFIash with mikrflKTn supper! P dsPICFIash programmer - an ultra fast USB 2.0 program- mer for the dsPIC30 microcon- trollers. Continuing its tradition as one of the fastest dsPIC30 programmer on the market, a new dsPICFIash with the mikrolCD now supports more dsPIC30 MCUs giving devel- oper a wider choice of dsPIC30 MCU for further proto- type development. mikrolCD debugger enables you to execute mikroC / mikroPascal / mikroBasic pro- grams on the host dsPIC30 microcontroller and view vari- able values, Special Function Registers (SFR), memory and EEPROM while the program is running. EasyPIC4 Development Board Complete Hardware and Software solution with on-board USB 2.0 programmer and mikrolCD Following the tradition of its predecessor EasyPIC3 as one of the best PIC development systems on the market, the EasyPIC4 has more new features for the same price. The system supports 8-, 14-, 18-, 20- , 28- and 40- pin PIC microcontrollers (it comes with the PIC16F877A). The mikrolCD (In-circuit Debugger) enables very effi- cient debugging and fast prototype developing. Examples in C, BASIC and Pascal language are provided with the board. LV24-33 Development Board Complete Hardware and Software solution with on-board USB 2.0 programmer and mikrolCD The system supports 64- , 80- and 100- pins PIC24F/24H/dsPIC33F microcontrollers (it comes with PIC24FJ96GA010 - PIC24 16-bit Microcontroller, 96 KB Flash Memory, 8 KB RAM in 100 Pin Package). Examples in BASIC, PASCAL and C are included in the system. You can choose between USB and External Power supply. LV 24-33 has many features that make your development easy. Explore new PIC24F/24H/dsPIC33F PIC MCUs with LV 24-33 and experience all advantages of these microcontrollers. PICPLC16B Development Board Complete Hardware and Software solution with on-board USB 2.0 programmer and mikrolCD PICPLC16B is a system designed for controlling industrial systems and machines. 16 inputs with optocouplers and 16 relays (up to 10A) can satisfy many industrial needs. The ultra fast mikrolCD (In- circuit Debugger) enables very efficient debugging and faster proto- type development. Features : RS485, RS232, Serial Ethernet, USB 2.0 on-board programmer and mikrolCD (In-Circuit Debugger) on- board. ARM Rash f ~ P ARMFIash programmer - ARMFIash is an USB 2.0 pro- grammer for the ARM family of Philips' microcontrollers. Very fast and easy to connect on the Board, it can program all the Philips ARM microcontrollers. You get the USB programmer which doesn't use boot loader or any similar way of program- ming. The whole ARM memory and all pins are available to you. Besides, you will have the state-of-the-art fast USB 2.0 ARM programmer for your future projects. 8051 prog E P 8051prog2 programmer - an ultra fast USB 2.0 program- mer for the Atmel 8051 micro- controllers.When connected to device or development system, it becomes an IN-SYSTEM pro- grammer. When plugged in ZIF socket, it becomes a standard programmer. You can order an optional ZIF socket, used for high volume production only. One of the possibilities of con- necting 8051prog2 to the microcontroller is via an IDC10 connector. The 8051prog2 can also program the latest models. f mikroElektronika manufactures competitive development sys- tems. We deliver our products across the globe and our satis- fied customers are the best guarantee of our first-rate service. The company is an official consultant on the PIC microcon- trollers and the third party partner of Microchip company. We are also an official consultant and the third party partner of Cypress Semiconductors since 2002 and official consultant of Philips Electronics company as well. All our products are RoHS compilant. http://www.mikroe.com/en/distributors/ - All of our products are shipped in special protective boxes. -On-line secure ordering provides fast and safe way of buying our products. Find your distributor: UK, USA, Germany, Japan, France, Greece, Turkey, Italy, Slovenia, Croatia, Macedonia, Pakistan, Malaysia, Austria, Taiwan, Lebanon, Syria, Egypt, Portugal, India, Thailand, Slovak Republic, Czech Republic. Uni-DS 3 Development Board with on-board USB 2.0 programmer The system supports PIC, dsPIC, AVR, 8051, ARM and PSoC microcontrollers with a large number of peripherals. In order to continue working with a different chip in the same development environment, you just need to swich a card. UNI-DS3 has many features that make your development easy. You can choose between USB or External Power sup- ply. Each MCU card has its own USB 2.0 programmer! LV 18FJ Development Board Complete Hardware and Software solution with on-board USB 2.0 programmer and mikrolCD System supports 64, 80 and 100 pin PIC18FxxJxx microcon- trollers (it comes with PIC1 8F87J60 - PIC1 8 Microcontroller with an integrated 10Mbps Ethernet communications peripheral, 80 Pin Package). LV 18FJ is easy to use Microchip PIC18FxxJxx development system. USB 2.0 on-board programmer with mikrolCD (In-Circuit Debugger) enables very efficient debug- ging and faster prototype development. Examples in C, BASIC and Pascal language are provided with the board. EasydsPIC4 Development Board Complete Hardware and Software solution with on- board USB 2.0 programmer and mikrolCD dsPICPRO 3 Development Board Complete Hardware and Software solution with on-board USB 2.0 programmer and mikrolCD The system supports 18-, 28- and 40- pin microcontrollers (it comes with the dsPIC30F4013 general purpose microcon- troller with internal 12-bit ADC). EasydsPIC4 has many fea- tures that make your development easy. Many of these already made examples in C, BASIC and PASCAL language guarantee successful use of the system. The ultra fast on- board programmer and mikrolCD (In-circuit Debugger) enables very efficient debugging and fast prototype develop- ing. EasyARM Development Board with on-board USB 2.0 programmer EasyARM board comes with t h e P h i I i p s LPC2214 microcontroller. Each jumper, element and pin is clearly marked on the board. It is possible to test the most of industrial needs on the system: temperature controllers, counters, timers etc. EasyARM has many features making your development easy. One of them is on-board USB 2.0 programmer with automatic switch between ‘run’ and ‘pro- gramming’ mode. Examples in C language are provided with the board. The system supports dsPIC microcontrollers in 64- and 80- pins packages. It is delivered with the dsPIC30F6014A microcon- troller. dsPICPR03 development system is a full-featured devel- opment board for the Microchip dsPIC MCU. dsPICPR03 board allows microcontroller to be interfaced with external circuits and broad range of peripheral devices. This development board has an on-board USB 2.0 programmer and integrated connectors for MMC/SD memory cards, 2 x RS232 port, RS485, CAN, on- board ENC28J60 Ethernet Controller, DAC, etc. BIGPIC4 Development Board Complete Hardware and Software solution with on-board USB 2.0 programmer and mikrolCD Following the tradi- tion of its prede- cessor BIGPIC3 as one of the best 80-pin PIC development systems on the mar- ket, the BIGPIC4 has more new features for the same price. System supports the latest 64- and 80-pin PIC microcontrollers (it is delivered with PIC18F8520). Many of these already made examples guarantee successful use of the system. Ultra fast on- board programmer and mikrolCD (In-circuit Debugger) enables very efficient debugging and faster prototype developing. Examples in C, BASIC and Pascal language are provided with the board. EasyAVR5 Development Board with on-board USB 2.0 programmer BIGAVR Development Board with on-board USB 2.0 programmer The system supports 8, 14, 20, 28 and 40 pin microcon- trollers (it comes with ATMEGA16). Each jumper, element and pin is clearly marked on the board. It is possible to test the most of industrial needs on the system: temperature con- trollers, counters, timers etc. EasyAVR5 is an easy-to-use Atmel AVR development system. On-board USB 2.0 program- mer makes your development easy. Examples in BASIC and Pascal language are provided with the board. The system supports 64-pin and 100-pin AVR microcon- trollers (it is delivered with ATMEGA128 working at 10MHz). Many already made examples guarantee successful use of the system. BIGAVR is Atmel AVR development system which is easy to use. BIGAVR has many features that makes your development easy. You can choose between USB or External Power supply. BIGAVR also supports Character LCD as well as Graphic LCD. Easy8051B Development Board with on-board USB 2.0 programmer [TjV m System is compati- ble with 14, 16, 20, 28 and 40 pin microcontrollers (it comes with AT89S8253). Also there are PLCC44 and PLCC32 sockets for 32 and 44 pin microcontrollers. USB 2.0 Programmer is supplied from the system and the programming can be done without taking the microcontroller out. EasyPSoC3 Development Board with on-board USB 2.0 programmer The system sup- ports 8-, 20-, 28- and 48- pin micro- controllers (it comes with CY8C27843). Each jumper, element and pin is clearly marked on the board. The EasyPSoC3 is an easy-to-use PSoC development system. On-board USB 2.0 pro- grammer provides fast and easy in-system programming. Please visit our web page for more info http://www.mikroe.com SOFTWARE AND HARDWARE SOLUTIONS FOR EMBEDDED WORLD 14 eleklor - 12/2007 DAC Board ADC with VREF CAN-1 Board CANSPI Board IrDA Board The MCP4921 is DAC with SPI inter- face that provide high accuracy and low noise perfor- mance for indus- trial applications where calibration or compensation of signals. The MCP3204 is 4-Channel 12 B i t A / D Converter with SPI Serial Interface. There is 4.096V voltage refer- ence on-board. The MCP2551 is High-Speed CAN Transceiver. It is used with MCUs that have integrated CAN module. The MCP2515 Stand Alone CAN Controller with SPI Interface. This board is used with MCUs that have SPI module. The MCP2155 is IrDA Standard Protocol Stack Controller that is easy to use for implement- ing IrDA stan- dard wireless connectivity. Compact Flash Board Easy way to use the Compact flash in your design and data acquisi- tion. Record and analyze the i nfo rm a- tion received by the MCU. RTC Board The PCF8583 is a clock/calendar with I2C bus interface. Keep track of the current time even when the MCU is turned off. Easylnput Board DIP switch is designed to be used on a print- ed circuit board along with other electronic com- ponents and is commonly used to customize the behavior. 3.3VReg Board Voltage regula- tor specifically designed for use in low input volt- age applications. This regulator can provide regulation changing your voltage from DC 5V to 3.3V Digital POT Board Digital Potentiometer with MCP41010 SPI Interfaced single-channel digital poten- tiometer on b o a r d . S e t potentiometer values from 0 ... 10 kohm. RS485 Board The LTC485 is a low power differential bus / line transceiver designed for multipoint data transmission standard RS485 applications. EEPROM Board EEPROM is typically used to store proto- type configu- ration parame- ters. AT24C02 is EEPROM with I2C bus interface. DIP to PLCC44 Board Professional and production adapter allows easy and fast working. You will have to press the PIC into the adapter. EasyPROTO Board Connects your prototype board with high quality IDC10 connec- tor. EasyMP3 Board Add MP3 to your prototype with VSIOOIk MPEG audio layer 3 decoder with SPI Interface. Screw terminal for easier con- nection with the external periph- erals. Accel. Board lrDA2 Board The ADXL311 is a low cost, low power, complete d u a I - a x i s accelerometer with signal condi- tioned voltage outputs. Board contains an oper- ational amplifier. The MCP2120 is Infrared Encoder / Decoder. This board also contains T F D U 4 1 0 1 (Infrared Transceiver Module). MMC/SD Board Serial Ethernet Board MMC card is used as stor- age media for a portable device, in the form that can easily be removed for access by a PC. ENC28J60 is a 10BASE-T stand alone Ethernet Controller with on board MAC & PHY, 8 Kbytes of Buffer RAM and an SPI interface. Port Expander Board MCP23S17 is the only 16-bit Input / Output expander that features SPI(tm) clock speeds up to 10 MHz for higher throughput appli- cations. PIC Experimental Board High Quality PIC Experimental board enables you to program microcontroller unit with ease. There are 8, 10, 14, 18, 28 and 40 pin DIP sock- ets. 5V-3.3VReg Board EasyConnect Board This regulator can provide local on-card regulation changing your voltage from AC/DC 8- 16V to 5V or 3.3V. Connects your peripherals easy and fast using high quali- ty on-board con- nectors. Useful in power as well as high-speed signal-handling applications. SmartMP3 Board PIC-Ready Board Add MP3 to your prototype with VSIOOIk MPEG audio Iayer3 decoder with SPI Interface. Low Voltage Audio Power Amplifiers and Voltage Level Selection - 5V or 3.3 V. High Quality prototype board with extension pin headers for 40 and 28 pin mcu will give you easiness of program- ming micro- controller unit. LCD Adapter - Connect your LCD (4x20 or 2x16) easily and save MCU pins. GLCD 240x64 Adapter - Connect your T6963C (Toshiba) 240x64 GLCD easily. GLCD 128x64 Adapter - Connect your 128x64 GLCD easily and save MCU pins. GLCD 240x128 Adapter -Connect your T6963C (Toshiba) 240x128 Graphic LCD easily. Serial LCD/GLCD Adapter - Connect your GLCD and LCD (4x20 or 2x16) easily and save MCU pins. Serial LCD Adapter - Connect your LCD (4x20 or 2x16) easily and save MCU pins. Serial GLCD 240x128 Adapter - Connect your T6963C (Toshiba) 240x128 Graphic LCD easily. Serial GLCD 240x64 Adapter - Connect your T6963C (Toshiba) 240x64 Graphic LCD easily. Keypad 4x4 Board Keypad can also be inte- grated as part of prototype that contains a calculator-style arrangement of buttons. Light to Freq. Board Add light to frequency converter to your prototype with TSL230BR programmable lig ht-to-fre- quency con- verter onboard. mikroBasiic for PIC MCU mikroPaGcol for PIC MCU A beginner? Don’t worry. Easy-to-learn BASIC syn- tax, advanced compiler features, built-in routines, and many practical exam- ples provided allow a quick start in programming PIC. mikroBasic for PIC has many routines and exam- ples such as EEPROM, FLASH and MMC, SD and CF cards support, writing character and graphics on LCDs, push-buttons oper- ations, 4x4 keyboard and PS/2 input, generation of signals and sounds, char- acter string tools, math calculations, I2C, SPI, RS232,CAN,USB, RS485 and OneWire comm., Manchester cod- ing, numerical conversion, PWM, interrupts, etc. Comprehensive, stand- alone Pascal compiler for the PIC MCUs. Develop your applications in an intuitive and friendly Pascal environment, using many advanced features and practical examples for PIC. mikroPascal for PIC has many routines and examples such as EEP- ROM, FLASH and MMC, SD and CF cards support, writing character and graphics on LCDs, push- buttons operations, 4x4 keyboard and PS/2 input, generation of signals and sounds, character string t o o I s , m a t h calculations, I2C, SPI, RS232, CAN , USB, RS485 and OneWire comm., Manchester cod- ing, numerical conversion, PWM, interrupts, etc. mikroC tar PIC MCU msec] The power and flexibility provided by ANSI C, with the most advanced IDE on the market. The perfect match. Plenty of practical examples and compre- hensive documentation. The mikroC for PIC has many routines and exam- ples such as EEPROM, FLASH and MMC, SD and CF cards support, writing character and graphics on LCDs, push-buttons oper- ations, 4x4 keyboard and PS/2 input, generation of signals and sounds, char- acter string tools, math calculations, I2C, SPI, RS232, CAN, USB, RS485 and OneWire com- munication, Manchester coding, numerical conver- sion, PWM, interrupts, etc. TTItkrDE3d5IC for tdsPI£3G.--33 and PICZ4 MCU mikroPascal far dsPIGO/33 and PICZ4 MCU n — — mikroC far dsPIOO/33 and PICZ4 MCU mikroBaisic for AVR MCU A beginner?Don’t worry. Easy-to-learn BASIC syn- tax, advanced compiler features, built-in routines, and many practical exam- ples provided allow a quick start in programming dsPIC30 / 33 and PIC24. mikroBasic for dsPIC30/33 and PIC24 has many rou- tines and examples such as EEPROM, FLASH and MMC, SD and CF cards support, writing charac- ter and graphics on LCDs, push-buttons operations, 4x4 keyboard and PS/2 input, generation of sig- nals, character string tools, math calculations, I2C, S PI, RS232, CAN, RS485 and OneWire comm., Manchester coding , numerical conversion, PWM, interrupts, etc. Comprehensive, stand- alone Pascal compiler for dsPIC30 / 33 and PIC24 MCUs. Develop your applications in an intu- itive and friendly Pascal environment, using many advanced features and practical examples for dsPIC30 / 33 and PIC24. Compiler has many routi- nes and examples such as EEPROM, FLASH and MMC/SD and CF cards support, writing character and graphics on LCDs, buttons operations, 4x4 keyboard and PS/2 input, generation of sig- nals, character string tools, math calculations, I2C, S PI, RS232, CAN, RS485 and OneWire comm., Manchester coding , numerical conversion, PWM, interrupts, etc. The power and flexibility provided by ANSI C, with the most advanced IDE on the market. The perfect match. Plenty of practical examples and acompre- hensive documentation. The mikroC for dsPIC30/ 33 and PIC24 has many routines and examples such as EEPROM, FLASH and MMC, SD and CF cards support, writing character and graphics on LCDs, push-buttons oper- ations, 4x4 keyboard and PS/2 input, generation of signals and sounds, char- acter string tools, math calculations, I2C, SPI, RS232, CAN, USB, RS4 85 and OneWire commu- nication, Manchester cod- ing, numerical conversion, PWM, interrupts, etc. 1 n,irtwiC| A beginner? Don’t worry. Easy-to-learn BASIC syn- tax, advanced compiler features, built-in routines, and many practical exam- ples provided allow a quick start in programming AVR. mikroBasic for PIC has many routines and exam- ples such as EEPROM, FLASH and MMC, SD and CF cards support, writing character and graphics on LCDs, push-buttons oper- ations, 4x4 keyboard and PS/2 input, generation of signals and sounds, char- acter string tools, math calculations, I2C, SPI, RS232, CAN, USB, RS48 5 and OneWire comm., Manchester coding, numerical conversion, PWM, interrupts, etc. mtkroPaE-ca] for AVR MCU Comprehensive, stand- alone Pascal compiler for AVR MCUs. Develop your applications in an intuitive and friendly Pascal envi- ronment, using many fea- tures and practical examples for AVR MCU. mikroPascal for AVR has many routines and exam- ples such as EEPROM, FLASH and MMC, SD and CF cards support, writing character and graphics on LCDs, push-buttons oper- ations, 4x4 keyboard and PS/2 input, generation of signals and sounds, char- acter string tools, math calculations, I2C, SPI, RS232, CAN, USB, RS48 5 and OneWire comm., Manchester coding, numerical conversion, PWM, interrupts, etc. Please visit our web page for more info http://www.mikroe.com SOFTWARE AND HARDWARE SOLUTIONS FOR EMBEDDED WORLD 12/2007 - elektor 15 REFLOW SOLDERING The Elektor lab needs to solder SMDs more often these days, something that undoubtedly also applies to many of our readers. In the January 2006 issue we described in some detail how you could build your own reflow oven using an inexpensive electric oven. That article resulted in many enthusiastic comments from our readers, which confirmed to us that there was a lot of interest in such a project. In this issue we present a completely new version of the control electronics for a DIY SMD oven. It is even available as a kit of parts, making the construction easy provided you know your bit about electrical safety regulations. Reflow Solder Controller Soldering SMDs in an ordinary electric oven Paul Goossens Our reflow oven is still used regularly in the Elektor lab two years since. As a result of the feedback from our readers we thought it was a good idea to come up with a more repeatable version of this project, and make it available as a kit of parts. This should enable many of our readers, we hope, to construct their own SMD reflow oven. For those of you who have not read the original article we shall first take a closer look at the reflow process. The end of the soldering iron? Conventional soldering is usually done with a soldering iron. Here you first heat up the parts with the solder- ing iron. Once the temperature is high enough you apply a bit of solder. This will melt and bond the two parts to- gether. The result is (hopefully) a good solder joint. This method is just perfect for use with conventional electronic components, since the connections are heated up one at a time and the chip itself re- mains relatively cool. A limitation of this method is that both parts to be soldered have to be accessi- ble to the soldering iron tip. With many SMDs (surface mount devices) this is difficult and with others it’s completely impossible! Reflow One of the methods used for solder- ing these components is called reflow soldering. Instead of heating the parts with a soldering iron, with this method the whole board, including all compo- nents, is heated! Standard solder is no longer used here; instead, use is made of a substance called solder paste. This grey material consists of extremely fine grains of sol- der mixed with flux. This paste is first applied to the pads on the board. The components are then placed on top of this. Everything then goes into the oven, where it is heated until the sol- der starts to melt and joins the compo- nent leads to the pads. Temperature profile This sounds simple, so why would we need a Reflow Controller circuit? An or- dinary oven should be able to do this job just fine! The reason is that for the soldering process to complete successfully, the board has to be heated and cooled fairly accurately in a certain amount of time. Figure 1 shows a measured tem- perature curve. The process begins with the ‘Pre- heat’ phase. Here the temperature in the oven is increased to about 125 °C. At this temperature the flux becomes liquid. The excess flux will flow away from the pads, leaving the grains of solder behind. The temperature then rises relatively slowly to 175 °C. This temperature is close to the melting point of the grains of solder. The reason for the gradual 16 elektor - 12/2007 Once this temperature is reached, the oven has to heat up the board and components to the maximum temper- ature (usually 220-240 °C). During this phase (called ‘Reflow’) the grains of solder melt and bond to the surround- ing metal. The solder joint is now ef- fectively made. After the maximum temperature has been reached, everything needs to rise of the temperature is that the board and the com- ponents need time to end up at the same temperature. In reflow terminolo- gy this is known as the ‘Soak’ phase. 250 Time [s] 1 060234-12 Figure 1. Temperature characteristic measured inside the oven. Figure 2. Circuit diagram for the Reflow Controller. 12/2007 - elektor 17 REFLOW SOLDERING Figure 3. A quick look inside the box. cool down again. This phase has the unequivocal name of ‘Cooling’. How- ever, this cooling shouldn’t happen too quickly; again this is to avoid large temperature differences between the board and components. Otherwise they may still deform or even break! On the other hand, the cooling shouldn’t happen too slowly, especial- ly at the beginning. Some components can only stay above a critical tempera- ture for a limited amount of time! Lead versus lead-free Broadly speaking, solder pastes can be divided into two groups, based on the composition of the solder. The metal used in solder is an alloy consisting of two or more metals. With most of the lead-based solder pastes this is an alloy of tin and lead (SnPb). This alloy has a melting point of 183°C. The second group, the lead-free pastes, usually consist of a tin, silver and cop- per alloy (SnAgCu). This doesn’t con- tain lead, which means it has a much higher melting point. It is only at 217°C that it begins to melt. When the latter group is used in sol- dering the maximum temperature in reflow soldering has to reach about 240 °C. With lead-free pastes 220 °C is suf- ficient, and sometimes it even works with a maximum temperature of 200 °C. This doesn’t only save time, but it also means that the components suffer less from the soldering process. According to the new RoHS regulations it is no longer permissible for consum- er electronics to contain lead-based solder, with a few exceptions such as automotive applications. Consequent- ly, you are still allowed to use it in the lab when building one offs and proto- types. As long as the gear you build is not offered for sale there is nothing to worry about. New design Now that we’re familiar with the ‘re- flow’ concept it is time to take a closer look at the controller circuit. The fact that we wanted to make this project available as a construction kit was another good reason for us to en- hance the original design. At first blush there wasn’t anything wrong with the first version, but we decided to modi- fy the electronics somewhat, based on our experiences with the previous de- sign and the feedback from our readers (thanks all for contributing to the forum topic on the 2006 oven). From this it became clear that nobody made use of the serial port. With this port you could display the change in temperature during the reflow proc- ess on a PC. Instead of this facility we thought it would be useful to show this on the display of the controller itself. In the new design we therefore left out the serial port and the EEPROM. We also replaced the 2x16 character LCD with a spiffy graphical display. As far as cost is concerned, it even turns out to be a bit cheaper and the end prod- uct looks a lot better. Another change is that both solid-state relays have been replaced with con- ventional relays. This was also done to reduce the cost. Circuit diagram The circuit diagram for the controller (Figure 2) is very similar to its cele- brated predecessor from 2006. At the heart of the circuit is controller IC1, an AT89S8253. In this circuit it operates at a frequency of 12 MHz. K5 is a programming interface, which can be used to program new firmware into the controller. A simple program- mer is required for this. The controller in the kit is ready programmed, so for most users this connector won’t be of much interest. The supply is taken care of by Trl, D3, IC4 and IC5, as well as a few other components to provide smoothing. As far as the power supply is concerned, we would like to point out that the construction kit is available in two versions: one for 230 V mains (most of Europe) and the other for 115 V mains (USA and some other countries). The only difference between the two is in the mains transformer. The mains voltage is connected via K9. This voltage is switched by relays Rel and Re2, which in turn are driven by FETs T1 and T2. The oven is connect- ed to K8. The temperature is measured using a thermocouple. This is connected via a cable and latching plug to K1 and K2. IC2 performs the actual measurement. 18 elektor - 12/2007 This IC converts the thermocouple voltage into an absolute temperature that is read by the controller via P2.0, P2.1 and P2.2. The connections for pushbuttons SI to S6 are very simple. They are connect- ed directly to inputs PI. 2 to PI. 7 of the controller. Remember that these inputs are also used during the programming of the controller. This means that you shouldn’t press any of the buttons when the controller is programmed via K5! Pullup resistor R2 is used to keep the inputs at 5 V when the circuit is at rest. The graphical LCD doesn’t have many surprises. Apart from the usual LCD in- terface there are also a few capacitors. These are used by the onboard elec- tronics of the LCD module to gener- ate the extra voltages required by the LCD. FETs T3, T4 and T5 drive the LEDs for the background lighting. In this case we decided on RGB lighting. The back- ground light can then be given any col- our by applying varying PWM signals to the three FETs. Which oven? Apart from the Reflow Controller board you obviously also need an oven to con- struct the project. It is absolutely vital that it is a fully analogue oven with a mechanical thermostat and a me- chanical clock. It should be able reach a temperature of 225 °C, and preferably a bit higher still. It is also advantageous if the oven has a small internal volume, as the tem- perature can rise more quickly in that case. A power rating of 1500 watts should be sufficient then. In practice you should find that just about any all-analogue pizza oven or mini-oven rated at 1.5 kW would work. With this version of the Reflow Control- ler it is no longer necessary to make ex- tensive changes to the oven. You only need to mount a thermocouple inside the oven. This can be done via a small hole in the side or on a bracket inside the oven. You have to make sure that the thermocouple remains galvanically isolated from the oven itself! The second modification is in the mains lead (cord). The normal mains lead is replaced by the lead included with the construction kit. This comes with a mains socket that fits to our Re- flow Controller. Construction and use The construction of the Reflow Control- ler (Figure 3) is straightforward. The building is limited to screwing the dif- ferent parts together and making a few connections. Full instructions are sup- plied with the construction kit. This manual can also be downloaded from the Elektor website. An introduction to the operation of the reflow oven is also included with this. ( 060234 - 1 ) Web Links www. e I e kto r. co m www.8052.com/visisp52/ Baking Components can adsorb some moisture from the air. During normal operation this doesn't re- ally matter, but this can cause problems with reflow soldering. The temperature of the chip will rise above that of the boiling point for water. The moisture in- side the chip will then turn into steam, which causes the pressure inside the chip to increase a fair amount. The result of this is that the chip can crack because of the presence of the steam. When the components have been stored in humid conditions it's possible to remove the mois- ture from them by heating them to about 80 °C for several hours. This is even more important when lead-free solder is used, as the pressure of the steam in- creases as the square of the temperature! The Reflow Controller has a special function that performs this baking process. Solder paste Apart from the grouping of solder pastes into lead and lead-free there is another possible grouping based on the type of flux used. The flux can be chemically active, which requires that the board is cleaned after the soldering process to remove any remaining flux from the board. There are also types of flux that exhibit some conductivity. Keep an eye out for these! The best pastes to use are those that have 'No-Clean' written on their label. This means that it's quite alright to leave the flux on the board after soldering. It won't corrode the board in any way, nor is the residue conductive so it won't affect the operation of the circuit. Another point to look out for is the size of the grains of 'tin'. The smaller these grains are, the easier it is to apply small doses to the board with a syringe. The rule of thumb here is: "the smaller the better"! Firmware As is usually the case with Elektor projects, the firmware for the microcontroller used in this project is available as a free download from our website. For the compiler we've used the free (!) 'SDCC' C compiler. If you want to include some of your own ideas to the firmware in the controller, you will need a programmer as well as this compiler. Our preferred software for this is VislSP-52. The associated programmer (which can be found on the vislSP52 website [2]) is easily built on a piece of experimenter's board. 12/2007 - elektor 19 TECHNOLOGY REFLOW SOLDERING TIPS Figure 1. Humidity indicator strips and desiccant bags should be part of your SMD reflow soldering toolkit! Reflow Techniques Using the Elektor SMD Reflow Soldering Oven Hagay Ben-Elie There is a bit more to using reflow soldering than just popping the circuit board in the oven and setting a simple timer. Modern SMT and BGA devices require special handling and strict processes. The steps and tips described in this article will remarkably increase the rate of success in assembling such novel projects. Tip #1: Baking and drying The chances of hobbyists to get newly manufactured devic- es in their original sealed vacuum packages are not very high, to say the least. It is more likely that second hand or salvaged components are used. Even with newly bought devices there is no way to know their storage conditions prior to reaching our hands. Components tend to absorb ambient moisture. This hap- pens all the time, even when already assembled and sol- dered in the circuit. This is not a prob- lem when manually soldering these de- vices as heat is applied to only one lead at a time and the entire device is not overheated. However, when placed in a reflow oven and heated to about 250 °C these devices can be destroyed due to what is known as the 'popcorn effect'. Moisture, at such high temperatures, is becoming steam that erupts from the device — most likely by cracking its case — and permanently destroying it. The same applies to printed circuit boards (PCBs), which absorb moisture during their production (etching) stage. When significantly heated, e.g. during a reflow process, this moisture becomes steam and usually erupts from vias and through-holes (TH). When steam erupts from holes filled with melted solder, it creates bubbles in the solder joints (voids) and even worse, scatters solder balls (splashes) all around. The best way to avoid these dev- astating effects is by simply drying PCBs and devices prior to being as- sembled and reflowed. This is often called 'baking', and is done by placing them in a specially designed 'baking oven', at 1 00-250°C for at least six hours (or even long- er). Moisture then evaporates without causing any harm to the items. Items are considered to remain 'dried' for about 48 hours, so baking/drying should be performed less than 48 hours before the reflow process. PCBs and devices are designed to withstand higher tem- peratures, so there is no impact on the behaviour or char- acteristics of these items. This, however, cannot always be said about the containers (tubes, trays, etc.) in which these items are stored. Make sure to bake items with no 'plastics' around them! Figure 1 shows humidity recording strips for use on an FPGA device — its purpose is all to clear! Allow for natural (not forced) cooling of items afterwards. As I don't know of any other homemade solution, the best way to bake items seems to be using the reflow oven itself. This feature was not implemented in the original (2006) version of the Elektor oven, but now it is! Tip #2: Solder paste Solder paste alloys are usually sold in large quantities as they are intended for industrial use. Minimum package size The art of SMT assembly differs immensely from what we got used to doing with TH assembly. 20 elektor - 12/2007 (called 'jar') is 0.5 kg (approx. 1 lb. and that is a lot! Nor- mal shelf life is about six months, and is achieved by storing it in a refrigerator. A normal kitchen refrigerator will do, but the jar must be adequately sealed and marked as 'non-ed- ible substance'. It is best if kept well out of reach of other family members and especially children. The stated shelf life is primarily intended for quality aspects during industrial use and mass production. For homemade projects, where no restrictions exist (life dependency, etc.), solder paste can be used as long as it keeps its original ap- pearance (colour, texture, viscosity). With proper storage conditions, 3-year old compounds may still do the job. Unless specially intended for, avoid using the new Pb-free alloys. The new RoHS directive dictates other soldering con- ditions for the industry — usually related to higher tempera- tures (up to 280°C) — which are above the rated condi- tions of current PCBs and components, nor are supported by the Elektor Reflow Soldering Oven. The best norma Baking/drying was not im version of the Elektor use alloy for non- industrial use is the Sn63Pb37 (63% tin, 37% lead) compound. It is easiest to use and gives the best results in terms of strength, appearance and conductivity. If possible select a compound with the finest granularity. Solder paste is, in essence, a blend of tiny solder balls and active flux. If a xl 0 to x30 microscope is accessible these solder balls may be actually observed. 25-45|j grains will give the best results. Refer to manufacturers' websites [1], [2] and [3] for further information. A new solder jar is always hermetically sealed to protect it against oxidation and moisture. Check it and avoid buying opened jars (unless received free of charge...). A sealed jar must be kept at room temperature and never refrigerated. Open the sealed jar just before using it. When re-using a re- frigerated jar, remove it from the fridge at least three hours before use. Keep it tightly closed and allow it to reach room temperature before opening and using. Otherwise, conden- sation might affect the compound — causing bubbles in the solder joints and solder splashes all over the circuit. Just before use, using a flat object like a knife or a spatula, gently blend compound to reach a uniform mixture. Avoid rapid stirring as this might let air to enter the compound and cause air bubbles (voids in the final solder joints. Instead, use gentle, smooth blending — just to make sure that com- pound ingredients have not got separated. Cleaning of solder paste residues (before soldering) is eas- ily performed using Isopropyl Alcohol (IPA). Tip #3: Visual aids As probably understood by now, a good visual aid is a must. A minimum x5 illuminated magnifying glass or pref- erably a xlO (or higher) microscope might make the differ- ence between good and poor solder joints. The bare eye can hardly locate shorts and/or bad solder joints smaller than 20 mils (0.02" = 0.5 mm). Tip #4: Solder paste application Solder paste must be applied to each pad on the PCB where components are to be assembled. During industrial use a special template, called stencil, is used. This is a 4-6 mils (0.004-0.006" = 0.10-0.15 mm) thick stainless steel sheet (mask), which is perfo- plemented in the original rated where sol- der paste should OVen, but now it is! be applied to the board. Solder paste is then spread on the stencil and squeezed into these small holes. Excessive paste is removed, and when the stencil is vertically lifted off the board only small solder paste dots are left on it, as required. This process is very expensive and, obviously, cannot be performed using our humble resources. A manual applica- tion method is more likely to be used. This is carried out by using a medical syringe as the application tool. Use a small (about 5-1 0 cc) syringe (Figure 2) — you'll be amazed how little material is being used. Fill it with a few drops (2-3 cc) of solder paste. Re-assemble it and connect it to a thick needle. Look for the thickest needles available — like the ones used for blood tests — and not those fine ones used for injections. Buy needles new and unused only. Using some kind of visual aid, as mentioned above, apply small dots of solder paste to each required solder joint. Ap- ply the smallest possible dots and try having them all in the same size. Especially keep them as uniform as possible for all joints of the same device. Remove excessive compound using a toothpick or gently wipe it using a cotton swab/bud dipped in IPA. Solder pastes have nominal on-board active life of about 8- 1 2 hours. This means that the board must be reflowed with- in this period of time since the first dot was applied. This is Figure 2. Not for the squeamish! Syringes and "guns 7 like the ones shown here will prove invaluable for applying solder paste on solder pads for SMD devices. 12/2007 - elektor 21 TECHNOLOGY REFLOW SOLDERING TIPS Figure 3. Special antistatic tweezers for SMDs are cheap and will not easily end up in the missus' beauty case. no problem when only a few components are to be assem- bled but gets complicated for larger construction projects. Well, no one promised you a rose garden... Tip #5: Placing the components Automatic pick & place machines are usually beyond the reach of the home worker. Fortunately, in most cases man- ual placement will be as good. Small chip components (re- sistors, capacitors) may be placed using small tweezers (Figure 3). For larger components (ICs) a vacuum pen is recommended. Observe orientation and polarity of devices and gently lay them in place. Don't press them down. Just let them hover on top of the solder paste dots. This requires some practice, though, but is not so diffi- cult to achieve. As with solder paste application, a good visual aid is essential. Special atten- tion should be given to precise location of the devices prior to releasing them on the board. Slight misalignments are self remedied (see below) but should be kept as small as possible. Trying to move misaligned devices will most prob- ably cause smearing of the solder paste dots and lead to poor solder joints and a bigger chance of shorts. For the real boffins among you, the 'BGA Challenge' is dis- cussed in the inset. Tip #6: Cleaning and inspection Most modem solder pastes are defined as non-cleanable, which means that the flux residues are not conducting and may, therefore, be left on the final product. Sometimes cleaning is simply impossible, such as beneath BGA de- vices. Cleaning also involves hazardous materials that are harmful to the inexperienced user and may contaminate the working place as well as pollute the environment. If, after all these warnings, cleaning is still desired, simply use the same materials and techniques as for ordinary TH soldering. As mentioned before, inspection of the final product is cru- cial. Solder joints are so small and delicate that shorts and bad joints are most likely. Using a good visual aid will help locating these mishaps and manually correcting them. Tip #7: Mixed technology double sided reflow, and some technical insights Where both reflow and manual soldering are required (as- sumingly most of the cases) reflow must be performed first. After all SMT/BGA devices are assembled, soldered, and checked it is easy to manually assemble and solder all other devices. Double-sided reflow, where needed, can also be performed quite easily. During industrial electronic assembly of double sided re- flow, boards undergo this process twice: once for the sec- ondary side (PS) and then for the primary side CS). During this process, the temperatures of the other side of the board are kept below solder melting point, thus not af- fecting the already soldered devices. This is not the case with the Elektor re- flow oven where temperatures on both sides of the board are likely to be the same. To overcome this we must use a small trick. Start by re- flowing only one side of the board — preferably with a smaller number of SMT/BGA devices. Wait for the board to completely cool down. Using epoxy adhesive, secure each device with a small drop or two. Larger PLCC or BGA devices might require four drops — one on each corner of the device. Apply small drops and avoid spilling on adja- cent conductors or leads. This is to allow replacing devices at a later stage without endangering the board or devices. Additionally, epoxy adhesive and solder have different ther- mal coefficients, causing them to expand differently while heated. This might cause pads to literally be torn off the board at high temperatures. Clean excessive adhesive and allow curing in accordance with manufacturer instructions. When completely cured, process the other side of the board is if it was the only side. A common mistake is to use SMT adhesive for secur- ing multileaded devices. This adhesive is best kept for chip components (resistors, capacitors, etc.) only. The soldering process of larger devices is obstructed if the devices can't move freely during reflow. Remember that devices need to float on top of the solder paste dots? The reason is simple. While melting, the solder dots simply collapse and cause the device to descend into place by means of the already mentioned facial tension. Each lead or ball is then con- tained within a small solder bead — creating a good elec- Fortunately, in most cases manual placement will be as good as industrial pick & place. 22 elektor - 12/2007 Tip #5.1: Ball Grid Array (BGA) Masterclass Placing a BGA (ball grid array) device is hard to perform but by no means impossible. Different BGA devices have different sizes, footprints, and balls' arrangements. Each device needs to be uniquely processed. First check that the device matches its designated footprint. Check for balls' arrangement, pad sizes and pitch (distance between two adjacent joints). If these all match then precise placing is to be determined. On com- mercially available PC boards, where silkscreen printing exists, check that the distance between outer rows of pads and mar- ked rectangle equals the distance between device's outer rows of balls and its contour. Check all four directions. When using non-marked boards, this rectangle needs to be manually drawn on the board (using an extra fine marking pen or a very sharp pencil). Otherwise, there is no practical way to put the BGA device in place. This stage, obviously, needs to be performed before applying solder paste to the board. As mentioned above, slight deviati- ons (or rather misalignments) are acceptable. During normal reflow process, while solder is liquefied, the facial tension wit- hin the solder (multiplied by the number of solder joints) has enough force to pull the device into place and compensate for small placing errors. As with other devices, use a vacuum pen to lay the device on top of the solder paste dots. Don't squeeze it. Let physics do its work. Finally, let it be said that BGA placement and soldering is an art of itself. Even industry experts do not always succeed in achieving 100% yield and sometimes need to replace BGAs at a much higher rate than other SMD devices. trical connection. Obviously, SMT adhesive fixes the device in one place and prevents it from "moving with the stream". The melted solder might then simply loose contact with the device's leads. When this happens to even one ball of a BGA device, where rework is impossible, the entire device may be rendered useless and needs to be completely re- moved from the board and replaced. An unthankful job! Tip #8: Removal of soldered multileaded devices If heat is used to solder these devices, why not use it for removing them? Since we usually deal with single or double layer boards, preheating of the other side of the board is normally not required. Multiple-layer boards usually tend to have internal discon- tinuities if processed without preheating since this exposes to a severe thermal shock (a significant thermal difference between both sides of the board . An electrical heat gun, such as the one used for shrinking tubing insulation or for removing paint from walls, is the perfect tool for this task. (Don't use the open fire type as it can burn the board and devices. Don't use a hair drier, as its air stream is not hot enough). This appliance is capa- ble of producing heat that will melt solder and that is just what it will do. Point the air stream at the device's leads and gently move it around. Avoid heating the case of the device. After a short while all solder joints will melt and stay liquefied even when air stream is not directly pointed at them. The device is then easily lifted off the board using small tweezers. Use desoldering wick (braid) to remove any solder residues from the pads on the board. Some final words The art of SMT assembly differs immensely from what we got used to doing with TH assembly. Yet, it is not beyond the capabilities of the average enthusiast. Some level of ex- periencing is required, but come to think of it — were you successful with your very first TH solder joints? Lets face it, TH assembly is about to go extinct for new de- sign. In this aspect the new Elektor Reflow Soldering Oven Controller is a real leap into the future. ( 070658 - 1 ) Note. A Powerpoint presentation showing equipment used for vari- ous steps in professional SMD board production and reworking is available as a free download (# 070658-1 1) with this article. Web Links 1 . www.kester.com/en-US/technical/alloy.aspx 2. www.aimsolder.com 3. www.ko-ki.co.jp/product/index.html Electrostatic Discharge (ESD) precautions A lot was said in the past about ESD but more than ever be- fore, these tiny creatures are susceptible to charges as small as 20 V! ESD will not always destroy the components but might rather cause latent failures that will affect their operation and significantly reduce their life expectancy. Following a few sim- ple rules will help us to avoid such failures: • Always keep active devices (transistors, ICs), in their ESD protective containers (trays, tubes, envelopes). Take them out only when needed. • Avoid touching devices' leads. Always hold their cases instead. • Use protected workstations. Desktop shall be always covered by a grounded working surface. Verify that electrical wor- king tools — soldering irons, reflow oven, etc. — are ade- quately grounded. Preferably connect all of them, together with the desktop surface, to the same grounding point — in order to minimize potential differences between them. • Use ESD protective wrist (or heel) strap. This cheap com- mercially available bracelet makes an excellent protective measure, as it removes any harmful charge off our body. High quality straps are equipped with an internal 1 MT2 re- sistor Assuming that the most common grounding connec- tion is the mains outlet earth terminal, this resistor protects us from the lethal voltages that may exist on power lines (or when accidentally plugging it to the mains Live terminal...). • The wrist strap's cord is better connected to the desktop protective surface, which is ground by another connection, rather than having them both grounded together. • And a final word about grounding the reflow oven (or at least its metal net shelf). This shelf, most likely used for pla- cing the reflowed circuit, should be electrically isolated from the grounded case of the oven. It should, instead, be groun- ded via the ESD grounding regime. This is to avoid rapid discharge of the ESD susceptible devices through metal con- nection — another way to destroy components. 12/2007 - elektor 23 MICROCONTROLLERS Low Cost - Low Power Holger Buss and Ulrich Radig, in collaboration with Dr. Thomas Scherer A web server using an Atmel controller cannot be for real — or can it? Perhaps it can, because in the world of Open Source technology seemingly nothing is impossible. What's more, it's entirely feasible to cram the code required into an ATmega32. External control and connectivity for a webcam make this project even more attractive. Figure 1. Completed web server with Ethernet card and serial interface. It all began, Ulrich Radig confesses, when he wanted to switch his coffee filter machine on using the Internet. Some nifty design work resulted in a Performance data • Web server with ATmega32/ATmega644 • Current consumption < 1 00 mA • Polling of three analogue inputs • 7 digital I/O lines • 1 -Wire interface (Dallas) • Connection for webcam • Interface for SD memory card • Polling of an NTP time server • Configuration by text file • e-Mail notification • Serial interface • In-circuit programming • Ethernet via NE2000-compatible ISA network card small web server with some Ports that allowed him to control and select analogue inputs. Having launched his design on the Internet [1], he soon attracted an enthusiastic following of like-minded individuals who im- proved his original concept by design- ing a host of hardware and software add-ons. Holger Buss then designed a PCB with ‘only’ two sides for a hook-up that linked it up to the Internet using an old NE2000-compatible Ethernet card [2] (Figure 1). Unlike many other small server designs, this circuit didn’t call for any SMDs. Ease of soldering is one advantage of that approach, along with minimal cost thanks to the use of low-budget new materials and recy- cled ‘ancient technology’ parts. Linux rules — or does it? Web servers tend to be bulky and noisy, housed in 19-inch rack cabi- nets and using Linux or Windows as their operating system. This picture is changing now as suppli- ers offer smaller form factors, such as housings for exter- nal hard drives that are distinguished not only by USB, eSATA or Firewire inter- faces but also the three letters NAS (standing for Network Attached Stor- age). Part of the standard specification is a speedy controller device operating at several hundred MHz plus a slimmed down Linux operating system. Server capabilities are configurable for proto- cols including FTR SMB and frequently HTTP as well, via a built-in web page. A few score megabytes of Flash and RAM are de rigeur. Despite all this sophistication an AT- mega32 has a mere 32 kilobytes of Flash memory and in matters of RAM you must make do with a whole 2,048 bytes! In consequence a microcontrol- ler cycling at 16 MHz is operating at a mere fraction of the rate of an NAS controller. And despite the ‘32’ in the ATmega32 designation, the ATmega series still uses true blue 8-bit CPUs. 24 elektor - 12/2007 This harks back all too strongly of the earliest beginnings of hobby compu- tery of at least 25 years ago, when for mega-money you could buy mon- ster A3-size PCBs populated with Z80, 6502 or 6800 CPUs. Compared to the fearsome cost of a KIM-1, AIM-65 or even Elektor magazine’s own modu- lar SC/MP system (does anyone still remember this?), you can buy a signif- icantly more powerful ATmega32 to- day for well under £ 5 ($ 10) and even the ATmega644 variant that’s blessed with twice as much memory sells for under £ 10 ($ 20). This economic and technical minimalism has a clear con- sequence: Linux is by no means the only fruit. Open Source? Little else remains on our agenda oth- er than to compress the vitally neces- sary elements of the Internet protocol so that they fit within the Flash mem- ory ‘brain power’ of an AVR controller. The authors were not the only ones facing this challenge and a number of other programmers had already done some valuable preparatory work along these lines. The good thing about Open Source is that you don’t have to reinvent the wheel from scratch. Con- sequently it didn’t take a huge amount of time to develop a web server on the basis of an AVR controller, especially as not only complete source code but also oven-ready compiled Make files were waiting on the project pages [3] and [4], which even not desperately software-minded folk could flash their controllers without any risk of making errors. There’s even a special forum [5] for anyone needing a bit of help. The capabilities of this little server can be found in the box-out along with the technical data. It’s quite amaz- ing how much punch this little pack- +5V 2 PROG 1 MOSI 4 3 „ 6 5 n 8 7 SCK n 10 9 MISO R3 GND RE .GND RESET MOSI RES ISA WR ISA RD IS A PB3 MOSI GND MISO MISO SCKP 1 SCK SCK +5V +12VO- GND v PD3 2 v PD5 4 v PD7 6 PA6 8 14 O O o o o o o o o o o o 1 3 PD4 5 PD6 7 PA5 9 PA7 11 _ 13 PD7 PD6 PD5 PD4 PD3 INTO PD1 PDO LED2 _20 J9 _18_ _r 7 _I6 _15 14 RIO lOOn GND X2 16 11 10 i_ 6 2 14 7 7 3 13 8 8 4_ 9 ru 5 _15 RS232 1- > vcc C1+ IC2 Cl- TIOUT T1 IN T20UT T2IN RUN R10UT R2IN R20UT C2+ MAX232 GND C2- > CO C8 -II 11 |C6 MOOn |C7 MOOn GND lOOn UA7805 $ 4 +5V X C5 lOOn GND DATA7 A7 A6 A5 RESET IC1 PBO (XCK/TO) PB1 (T1) PB2 (AIN0/INT2) PB3 (AIN1/OCO) PB4 (SS) PB5 (MOSI) PB6 (MISO) PB7 (SCK) PA7 (ADC7) PA6 (ADC6) PA5 (ADC5) PA4 (ADC4) PA3 (ADC3) PA2 (ADC2) PA1 (ADC1) PAO (ADCO) 33 PA7 34 PA6 35 PA5 36 ADR4 37 ADR3 38 ADR2 39 ADR1 40 ADRO ATmega32 PD7 (0C2) PD6 (ICP) PD5 (0C1A) PD4 (0C1B) PD3 (INTI) PD2 (INTO) PD1 (TXD) PDO (RXD) PCO (SCL) PCI (SDA) PC2 (TCK) PC3 (TMS) PC4 (TDO) PC5 (TDI) PC6 (TOSC1) PC7 (TOSC2) I a X CD 22 DAT AO 23 DATA1 24 DATA2 25 DAT A3 26 DATA4 27 DATA5 28 DATA6 29 DATA7 22p Cl u C2 22p GND +5V 2x o 1N4148 £2 +5V 5V O CIO DO Dl CS SCK CO CO / / \ V CO CO o m o CO CL s R11 R1 R2 R5 MMC/SD Card C12I 22u 0£ R9 GND GND. XI s. DATA6 A3 ^ DATA5 A4 ^ DATA4 A5 v DAT A3 A6 v DATA2 A7 v DATA1 A8 ^ DAT AO A9 A_10 All A12 A13 A14 A15 A16 A17 A18 A19 A20 A21 A22 A23 v ADR4 A24 A25 A26 A27 v ADR3 A28 v ADR2 A29 v ADR1 A30 v ADRO A31 B11 B12 B13 B14 B22 B23 B24 B25 X GND RESET RESJSA IRQ9 INTO WRITE WR ISA. READ RDJSA IRQ7 IRQ6 IRQ5 IRQ4 IRQ3 INTO. 060257 - 11 Figure 2. The circuit of the web server is unbelievably simple, as network connection is outsourced to an Ethernet card. 12/2007 - elektor 25 MICROCONTROLLERS w o Q CO Q | z CM O. Q CO O ^ Q O O Z > CO O co 't, in 1 -* * jta*r.*r Th.p * bwwf Art MA |VA iV Twfrt AM Art *.*--** II M-Vn ftt pi jj A Ik .m IMLlT «i U . AL ■ 1 9*1 A "PITO--1P Milm, tm fartMi** I*h- rn-gWpfA'hMV A □ - H*- Si BHIW Mltrv Figure 1 1. This is the message display from our prototype web server in the Elektor lab. ifkina is?* lmiiiii mii-i "’At ■? i Tl \ T - ''' vi 28 elektor - 12/2007 o Soldering .co.uk Suppliers ofPCB Soitianog Equipment £ Rework Stations 10 %0FF Inter Discount Code At Checkout Qillie Orders I xmso7 wwwucli-sofflerm. co.uk Valid hum 15/01/01 •tit Includes: HfUJtoeuri &aA' NouIh WW Soldermi} Iran wrtK F-umn AJbioibc! 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Hs^refiftlui* FN > I OFF F 4011097 4 SOTS 1 E s*ltfcg&(Xb"Wldenilo «. uN n r~\ /~\ A N T E X \ / LJ \_J \ / \ / Antex offer a wide choice of input voltages and bit profiles for our soldering iron range AM ft* Ml 2 230V -<£ MU 230V t £ 60+ years of experience It may surprise you but buying an Ante* soldering iron costs less than you think in the long run. British made to exacting standards, they last significantly longer than many imported brands- With a wide range of thermally balanced models, and temperature controlled irons too, you can always be sure to find an iron that meets your needs., A largo range of replacement tips are available for most irons, and technical help is on hand from our offices in Devon UK. Buy Online Our new website has all of our irons, and soldering spares and accessories available 24hrs a day. Most items are shipped next day, and we offer free carriage throughout Europe. Why not give antex.co.uk a try! www.antex.co.uk FREE shipping on all orders Antex Electronics Ltd 2 Westbridge Industrial Estate Tavistock, Devon PL1 9 8DE, UK Tel: +44(0)1 B22 613565 Fax: +44(0)1822 617598 Email: sales@antex.co.uk Web: www.antex.co.uk 12/2007 - elektor 29 TEST BENCH Antoine Authier & Guy Raedersdorf Sensory® has been well-known for over five years for its modules that make it possible to add voice recognition to an electronic product. As so often the case in electronics, things are evolving very fast. We were lucky enough to have the latest baby from the Sensory stable, the VR Stamp™ Toolkit, arrive on our desk. Let's take a little look at what it has to offer. Let's start right away by clearing up a puzzle - what do the two letters VR mean in the prefix of the various Sensory® products? Well, they're quite simply the acronym for Voice Recognition. What's it for? The VR Stamp™ from Sensory fulfils a triple role: to give any kind of product a voice recognition capability, to make it possible for it to 'speak', and lastly, to give it the capacity to synthesize music. The VR Stamp is the first speech module (combining voice recognition and speech generation) to use the Quick T2SI (Text To Speaker Independent) technology from Sensory - not at all surprising, since it is the intellec- tual property of this company. It takes no more than a few minutes to be able to create a voice module. Another attrac- tion of this approach is its support for different languages (up till now, we've generally been limited to just English), making it possible to envisage creating products practically anywhere in the world. The box is a real treasure-chest: a mother board with ZIF socket for the VR Stamp Module and a serial EEPROM allowing data to be re-written, a power supply, a pair of CD-ROMs, a USB cable, and even a USB dongle (!) used to protect the compiler. Piggy-back board In the first photo (Figure 1) we see the VR Stamp™ Toolkit, which serves as a support for the VR Stamp™ proper, i.e. the VR Stamp™ Module. 30 elektor - 12/2007 Technical specifications FluentChip Technology • Recognition, both SI (Speaker Independent) and SD (Speaker Dependent) • Several language modules for international applications • High-quality 2.4 compression at 10.8 kbps • Sound effects supported by Sensory's 'SX' synthesis technology • SVWS (Speaker Verification), biometric security by vocal password • 8-voice MIDI-compatible music synthesis • DTMF tone synthesis • Standby mode for audio amplifier VR Stamp™ Module • RSC-4128 speech processor • 1 Mbit Flash memory • 1 28 kbit data EEPROM • Dual clock (system 14.3 MHz and crystal-controlled 32 kHz time-keeper) • 24 Input/Output lines • Mic preamp • PWM for speaker • Optional DAC output • Low power consumption: 26 mA @ 3 V, <20 yL/A in standby The Toolkit comprises everything you need to program the VR Stamp™ as you wish. In reality, the Toolkit is a program- ming tool used to transfer an application program into the VR Stamp module via a PC USB port. The board uses a ZIF (Zero Insertion Force) socket that lets you insert and remove the Module without risk. The VR Stamp™ is a small circuit board in standard 40-pin DIL format (pin 1 of the module must be at the insertion lever end of the socket). After programming, it can be plugged directly into the application. The Toolkit comes with a pair of CD-ROMs: the Toolkit CD and the Phyton CD-ROM with a 3-month limited version of this company's C compiler. At the heart of the module The heart of the VR Stamp is an RSC-41 28 processor from Sensory's own foundries. If you want to know more about it, we can do no better than recommend you to take a look at its datasheet [1]. The interesting aspect of this series of dedicated processors in the RSC-4x family is that they sup- port the FluentChip™ technology, which employs extremely high-performance algorithms that allow greater possibili- ties and also more accurate processing (recognition and speech). Besides its voice recognition functions, the RSC-4x family is characterized by the presence of a certain number of on-board functions, including for example a microphone preamplifier, a pair of DMA (Direct Memory Access) units, a vector accelerator, a hardware multiplication unit, three timers, and not forgetting almost 5 kB of RAM used for temporary storage of data being processed. Given all the functions crammed into the processor, only a few additional components are needed to produce an operational project: a speaker, a microphone, power (battery), and a handful of resistors and capacitors. Figure 3 show the block diagram of it. Don't be deceived by this, as it's extremely simplified. Besides the lines shown here for power, mic and speaker connections, and an RS- 232 interface (SERIAL PORT), there are also no less that 24 I/O lines available. Let's get down to business! After this brief introduction, it's high time to get an idea of how this tool is used in practice. Contrary to the usual practice of many of us, let's start by reading the documentation on the CD-ROM. After that, the first step consists of installing the support programs. First of all, you need to locate on the CD-ROM Figure 1. The VR Stamp™ Toolkit is in fact a mother board, onto which theVR Stamp™ Module is piggy-backed. Figure 2. TheVR Stamp™ Module in all its splendour. Figure 3. If you have an eye for technology, you'll doubtless be impressed by the apparent simplicity of such a high-performance component. 12/2007 - elektor 31 TEST BENCH Figure 4. Snapshots of what happens on screen when using this development tool... i HiriJ * mz J FluentSoft™ SDK Now if you really want to get down to the nitty-gritty of speech recognition modules, you'll need to get to know the Flu- entSoft™ SDK - a development tool that allows voice recogniti- on technology to be incorporated into top-end consumer elec- tronics. Although the voice recognition is high quality, owing to the revolutionary approach adopted, the resources required in memory and CPU power remain limited. It's worth noting that this development tool has been designed to run on different platforms and operating systems, from the Intel and ARM processor kernels to Windows, Linux, or Sym- bian OS. The creation of an application comprises several steps: • Compilation of the Vocabulary • Configuration of the Speech Detector • Choice of the Acoustic Model • Configuration of the Recognizer... Enough there to keep you occupied for a little while... the USB drivers (which are none other than virtual FTDI COM port emulation drivers - in our case, the rather old 1 .00.2154 version). You will be asked for them the first time you connect to the computer with the development board powered up. Then you will be able to unpack the software package. In order to use the Quick T2SI application, you'll first need to register your copy on the Sensory website: http:/ /fluent- speech .com/ t2silitereg/. The QuickSynthesis 4 software for managing your sound synthesis presents no special difficulty, the screen dump in Figure 4 will give you some idea of it. In order to be able to use the FluentChip tools, you'll need to install Phyton. This requires installation of the Rainbow dongle drivers and will entail rebooting the computer (un- der Windows). Let's get started! There's nothing so reassuring as to see an LED light up, a screen come to life, or indeed a speaker make itself heard. It only takes a few components (see circuit in this box) to pro- duce a little extension that lets you confirm the operation of the piggy-back board and its 'baby'. The extension plugs into the extension connector (the 2x17 contacts starting from the bot- tom, GND). It's worth noting that for a quick preview, only SensoryLoader4 is really necessary. This makes it possible to flash the binary and Hex File programs provided as examples in the 'demos' directory. Most of these examples need a small extension, a few push-buttons and check LEDs (see circuit in box), in order to check the running and functions of the programs. We were able to try out all the example programs as well as some compilations. The examples, • Recognition of multiple words, 54-01 26B, • Speaker recognition, 54-01 28D, and • Recognition applied to home automation, 54-01 77b, are amusing and quite convincing. VDD 32 elektor - 12/2007 The competition In the past, we have seen various circuits: one capable of syn- thesizing words to generate phrases with a very artificial tim- bre (Texas Instruments - you had to visit their laboratories to record, with great difficulty, the texts to be stored in ROM, and there was no question of changing anything later); the other able to convert words into synthesized sound (the SP0256 from General Instruments, which knew only 59 English phonemes - mostly numbers and figures - and 5 pauses of various lengths; just try saying anything meaningful with these rudi- ments of language!). And a third, like the TTS256, which is not, contrary to what one might think, from Texas Instruments, but from Magnevation. Another component from this same company does deserve a mention: its SpeakJet [3], programmed with 72 speech ele- ments (allophones), 43 sound effects, and - yes, you have to read it to believe it - 1 2 sounds corresponding to the DTMF dial tones. Choosing judiciously from these various elements and combin- ing them with different variable parameters such as volume, pitch, roundness, and frequency makes it possible to produce all the phrases and sound effects in the world. But it's never- theless a really painstaking task. Once the drivers are correctly installed and the dongle recognized, Phython ought to install without problem. Phy- thon Project-SE offers a simulator and an on-chip emulator, in addition to the development, assembler, and compiler environment. The screen dumps illustrate different stages in using this universal tool. Tools The Toolkit provides samples and demonstration modules illustrating the technologies Sensory employs to simplify to a maximum the development of everything related to voice recognition and speech generation. QuickSynthesis™ 4 al- low recordings of speech to be compressed quickly with the right combination of size and quality. On the Toolkit CD-ROM are the FluentChip™ technology library, and the QuickSynthesis™ 4 and Quick T2SI-Lite™ tools supporting language packs, allowing creation of vo- cabularies on a world-wide level. The latter module's Lite suffix is certainly justified, as it is limited to 50 vocabulary creations or 6 months' use, whichever is reached first. On the second 'Phyton' CD-ROM we find an IDE (Integrat- ed Development Environment) comprising an assembler, a linker, and a C compiler (restricted as mentioned above). All the technologies offered by the FluentChip™ library are available for use on the VR Stamp, with the exception of Record & Play (due memory constraints). A fascinating world If you're interested in the subject of speech synthesis in all its various aspects, we can do no better than recom- mend you to pay a visit to the website referred to in [2] of the links. You'll see that there are many roads leading to Rome, but none of them has the universal capabilities of the VR Stamp™ Module. ( 070372 - 1 ) Bibliography and links [1 ] http://backoffice.inware.it/files/prodotti/download/ sensory/ rsc41 28data.pdf [2] www.speechchips.com/shop/ [3] www.sensoryinc.com/ [4] Distributor : www.tigal.com 12/2007 - elektor 33 PROJECTS PCB DRILLING Controller ImKj) = DQQ®0© David Clark Designing and making a printed circuit board (PCB) for a project has many advantages over using stripboard, but there is one big disadvantage - drilling the holes. Our Craft Drill Controller takes away some of the tedium of this task by semi- automating the way a 12V mini drill has its speed controlled, so saving time and drill bits! For example, the final speed for the drill can be preset, as can the time the drill takes to speed up to, and slow down from, this final speed. The drill can be run in this ‘timed’ mode, or can be run continuously as normal. Fur- thermore, the drill can be switched on and off via a footswitch, leav- ing both hands free for position- ing the drill and the PCB. The Craft Drill Controller is also useful for the control of other ‘mini’ cutting and polishing tools that can be fit- ted to small 12-V powered drills of the ‘Dremel’ and ‘Proxxon’ vari- ety, which come in a wide range of product qualities, of course matched by the price tag. Accuracy vs. Tedium The recommended way of drilling a PCB is to use a mini drill running while fixed in a small drill stand. However, this method is slow and inflexible. The alternative, hand-holding the drill, can easily result in imprecise position- ing and/or the drill ‘skidding’ across the PCB, an equally frustrating situ- ation. The Craft Drill Controller over- comes these difficulties in the follow- ing ways: 1 . The controller automatically switch- es the drill on and off, allowing the user to carefully position the drill while it is off and then hold it in position until the drill starts. 2. Drill-on and drill-off times can be individually set. 3. The same for the speed-up and slow-down rates for the drill as it ‘ramps’ between off and its final speed and vice versa. 4. The final speed, too, can be set by controller. 5. Footswitch control is optional, keeping both hands free to position the board and lower the drill. All settings can be ‘fine-tuned’ in such a way that the user quickly establishes a ‘rhythm’, according to his/her own natural pace in using the drill, which speeds up the drilling process and relieves much of the te- dium of this job. Principle Of Operation The Craft Drill Controller does not pro- vide the power to the drill, but instead is connected between the drill and its conventional DC power supply (set to maximum), and it controls how the supply power is applied to the drill. A block diagram for the Craft Drill Con- troller is shown in Figure 1. Control of the drill speed is achieved by a form of pulsewidth control, in which three lev- els of pulsewidth control are combined to control overall on/off timing, ramp up/ramp down rate, and final speed. The circuit Let’s have a look at the circuit diagram shown in Figure 2. Apart from a five- volt regulator, the circuit is built entire- ly around general-purpose transistors, bipolar ones (BC550C; BC560C, TIP122) as well as FETs (BS170; BS250P). The pulses are generated by three astable multivibrator circuits; the timing of these is, however, controlled by vari- able constant-current capacitor charg- ing rather than the usual capacitor-re- sistor timing. This gives better timing and more linear control settings. The first astable multivibrator is based around transistors T14 and T16. T8 and T10 are the constant-current sources, the currents being set by eternally connected potentiometers P3 and P4. These control the ‘on’ and ‘off’ times of the astable, which correspond to the on and off times for the drill. In the circuit diagram, ‘ccw’ means counter- clockwise, this indicates one of the outer legs of the pot the wire has to be connected to. The centre leg (c) of a potentiometer is invariably the ‘wiper’ and goes to the centre pin of the rel- evant connector. 34 elektor - 12/2007 The outputs from the first astable are applied, via FET buffers T12 and T13, to the two sets of ‘ganged’ (a.k.a. ster- eo or ‘tandem’) potentiometers that control the charging currents for the second astable, which is based around T5 and T6. This second astable controls the ‘speed-up’ rate applied to the drill when the output of the T14/T16 asta- ble switches the drill on, and the ‘slow- down’ rate when the astable causes the drill to be turned off. The output of the T5/T6 astable pass- es, again via a buffer, Tl, to what is in effect an AND gate, consisting of di- ode-resistor logic components Dl, D8 and Rl. Thus the output of this asta- ble ANDed with the output of the next astable, which is based around T15/ T17. This one sets the final, i.e. maxi- Figure 1. Block diagram of the Craft Drill Controller. Electrically, the circuit sits between the 12-15 V PSU and the hobby drill. P1A f 1N4 cw 2x D6 48 DIO cwl 1? 1 ? ?1 _J ( h- lli Li) P2A k CW Figure 2. All three astable multivibrators in this circuit are built from discrete parts. An improved control characteristic for the various ramp voltages generated by the circuit is achieved by using constant current sources rather than R/C networks. 12/2007 - elektor 35 PCB DRILLING mum, speed of the drill by controlling the mark-space (on/off) ratio of the pulses applied to the drill motor via a power Darlington transistor, T7. The ‘mode’ of the drill controller, i.e. continuous or timed mode, and foot or panel control, is determined by switches S3, S4, S5 and S6, which sim- ply ‘route’ the motor control pulses. Various light emitting diodes (LEDs) indicate the state of operation at any moment. Two more switches on the rear panel of the Craft Drill Controller control power to the controller circuitry as supplied by the external power supply, which must of course match the power re- quirements for the drill. A main power switch should be provided on the back panel, controlling the supply to both the drill and the controlling circuit. SI allows the power to the drill only to be Figure 3. Pictorial representation of connections of some of the external controls to the circuit board. switched off, for when it is required to P3 ‘Short-Long’ P5 ‘Final Speed’ ‘Slow-Fast’ m ¥■ 1 ] 1— 1 B P1B cw c CW c CW c CCW P5B >cw >c >ccw P5A >cw >c >ccw P4 ‘Short-Long’ S5 ‘Continuous’ Panel Switch Control P2B CW c CW c CW c CCW NO -c •NC 060192 - 15 COMPONENTS LIST Resistors Rl / R28 / R29 = 1 00D R2 / R6 / R9 / R1 0,R15,R18,R21,R2 4 = IkQ R3 = 1 5D 2W R4,R30 = 2kQ2 R5,R1 2,R1 3 = 15kD R7,R8,R1 1 ,R1 6,R1 7 / R22 / R23 = 4k QJ R1 4,R1 9 = 2kQ7 R20, R25 = 1 OkD R26,R27 = lOOkD PI ,P2 = 5kD linear-law potentiometer P3,P4 = 1 OkD linear-law potentiometer P5 = 50kD linear-law stereo potentiometer Capacitors Cl = lOOnF C2 = 470nF C3 / C4 / C7 / C8 = 220a/F 25V radial electrolytic C5,C6 = 220nF C9,C1 0 = 22nF Semiconductors 01,06,07,08,09,010,01 1 = 1N4148 D2,D3,D4,D5,D1 2,D1 3 = LED, low current T1,T4 = BS170 T2,T3,T8,T9,T1 0,T1 1 = BC560C T5,T6,T1 4,T1 5,T1 6,T1 7 = BC550C T7 = TIPI 22 T12,T13 = BS250P (watch suffix P) IC1 = L7805CV Miscellaneous 51 = on/off switch, 1 make contact 52 = on/off switch, 1 make contact 53 = footswitch, on/off, 1 make contact, see text. 54 = single-pole changeover switch 55 = single-pole changeover switch PCB, ref. 060291-1 from ThePCBShop; free artwork download # 060291 -1 .zip from www.elektor.com Front & rear panel artwork files, free down- load from www.elektor.com Figure 4. Component arrangement on the printed circuit board designed for the Craft Drill Controller. Copper track layouts available free from our website. have the controller running but to en- sure that the drill is not allowed to run accidentally. To prevent supply voltage fluctuations affecting the timing circuits, these are powered via a 5-volt regulator, IC1. To reduce inefficiency and over-heating in IC1, resistor R3 drops the voltage ap- plied to the regulator input. A 2-amp fuse should be connected be- tween the PSU and the supply input of the controller to protect the overall circuit. The controller was designed to oper- ate with a supply of between 12 and 15 volts DC. Nevertheless, it should be possible to use drills of higher voltage and power if component specifications are uprated, in particular those of the fuse, R3 and T7. Heat sink requirements for IC1 and T7 should also be consid- 36 elektor - 12/2007 ered - in the prototype they were fixed to the inside of the aluminium rear pan- el using insulating washers. Construction Construction is straightforward thanks to the use of none but standard leaded components that might well be lurk- Populating the board is a breeze as there are no SMDs or multi-legged microcontrollers to fit. ing in your junkbox, with no special measures or setting up required, oth- er than the usual care over handling electrostatic-discharge (ESD) sensitive components. The component mounting plan of the double-sided printed circuit board we’ve designed is given in Figure 4. The .pdf file with the copper track lay- outs (reflected and non-reflected) for home production of the circuit board is available as free download from the Elektor website. Populating the board is a breeze as there are no SMDs or multi-legged microcontrollers to fit. The connections to the external com- ponents (switches and pots) are illus- trated in Figure 3. Work with care and take your time to do this wiring job. The blue, dashed, lines in the circuit diagram indicate that potentiometers PI and P2 are ganged versions operat- ing in tandem. Your completed, wired up board should look something like our lab prototype It should be possible to use drills of higher voltage and power if component specifications are uprated. pictured in Figure 5. Do not fit your board into a case before it has been tested ‘live’, i.e. with a power supply and a drill connected, and you are sat- isfied with the operation. If you find that a pot regulates the wrong way around, simply swap the wires to the outer legs. Figures 6 and 7 show suggested lay- outs for front and rear panels, respec- tively, for a housing for the controller. Figure 5. Our fully working, populated and wired up board. D3 P4 \ \ P2 \ P5 j D2 \ Hhc-r! LDf>g Slow I -*U On Time Speed ■ Up Rate Timer Shan Long FarH Off Slow-Down Rile F**l Final Speed Cant***** M' TW+S Speed Control t t D13 P3 t PI t t D4 S5 Circuit Power Q Drill Pwwer 0- 3 Kara l l-u Output Switch R,ri OQ o Drill t D12 A A — Ml — D2 S4 S2 Figure 6. Suggested layout for the front panel (file for full-size artwork available as a free download). Figure 7. There's a few things on the rear panel, too, and this is how you could arrange and label them (file for full-size artwork available as a free download). 12/2007 - elektor 37 PCB DRILLING The artwork for these panels is also available as a free download for editing and/or scaling (if you want) using your favourite graphics design program. As the diagrams indicate, 4-mm plug (banana) sockets were used for connec- tions to the drill and the power supply, and a 0.25-inch (6.3 mm) jack socket was used for the footswitch connector. The footswitch itself can be a latching or non-latching type as preferred. In Use - your preferences rule Make sure the main power on/off and drill power switches are off, and then Safety First The usual precautions regarding eye protection etc. apply of course, par- ticularly when using a hand-held drill with a small tungsten carbide drill bit, as these can be brittle and prone to breaking under sideways stress. Timed or Continu- ous oper- ation - set the ‘Speed Control’ switch on the front panel. If timed operation is selected, adjust the four Timer controls until a comfortable working ‘rhythm’ is achieved by varying how long the on and off cycles are, and how long it takes to speed up to, or slow down from, the final speed as set by the Final Speed control. If continuous operation is want- ed, switch the drill on and off as required, at the speed set by the Final Speed control, using the footswitch or Run switch as selected above. The Final Speed setting will be chosen according to the material being drilled or perhaps according to the tool being used if the controller is used with, say, a polishing or grinding tool. Safety pre- cautions are mentioned in the inset. In Conclusion The Craft Drill Controller is a low-cost circuit of whose functionality and ver- satility is surprisingly hard to find com- mercially. It should make perhaps the most time-consuming part of produc- ing a PCB a little more pleasurable, and get rid of the final excuse for choosing stripboard over a purpose-designed PCB, for the electronics constructor without access to a high-end program- mable drilling machine! ( 060291 - 1 ) connect the power supply and the drill to the controller, and a footswitch if one is required. Switch the main power on/ off switch to on, but do not switch the drill power switch on until everything is set up and ready for use. How the controller is used will of course depend on the job in hand, the choices being for: footswitch or front panel control - flip the Foot/Panel switch. The drill can then be switched on and off using the footswitch or the ‘Run’ front panel switch as selected, for either: PoScope is a low-cost USB- based instrument that adds invaluable test equipment features to your desktop or notebook PC. Being PC-based, all measurements can be printed, copied to the clipboard and saved as text, bitmap or vector graphics for subsequent analysis or to import into other programs. PoScope is ideal for use by electronics hobbyists, students and engineers alike and is particularly suited to those developing with microcontrollers such as PIC and AVR. PoScope provides the following operation modes: • 2-channel oscilloscope with 100Hz to 200kHz sampling, -20 V to +20V input range, 10-bit ADC resolution, absolute, differential and external triggering, adjustable pre-trigger and marker measurements. • 2-channel spectrum analyser with klirr factor measurement, Hamming, Hanning, Blackman and Blackman-Harris FFT window functions. • 2-channel chSrt recorder with 0.01Hz to 200kHz sampling, maximum, minimum and average voltage measurements for each channel and waveform record over several tens of hours. • 16-channel (8 when pattern generator used) logic analyser with 1kHz to 8MHz sampling, versatile triggering with adjustable pre-trigger, external clocking, preset pulse miss, preset bit sequence/edge, decoding of UART, SPI, I2C and 1-wire serial interfaces. • 8-channel 1kHz to 1MHz pattern generator with tabular waveform formatting or direct timing chart plotting on the screen. • Square-wave/PWM (pulse width modulation) generator. Compatible with Microsoft Windows ME, 2000 and XP, PoScope is supplied with easy- to-use software and a USB cable. Oscilloscope probes and logic analyser test lead/clip sets are available separately. equipment can of test £ 99 ? With a PoScope USB instrument you get the features of an oscilloscope, spectrum analyser, chart recorder, logic analyser (with UART, SPI, l 2 C and 1 -wire serial bus Tl decoding), pattern generator and square-wave/PWM generator. That’s equivalent to six pieces of test equipment for £99 including UK cfejivew and VAT Order now on Freefone 0800 612 2135 or online at www.paltronix.com PALTROniK EQUIPMENT FOR ELECTRONICS DEVELOPMENT, TRAINING & EXPERIMENTATION Paltronix Limited Unit 3 Dolphin Lane, 35 High Street, Southampton SOM 2DF Telephone: 0845 226 9451 Facsimile: 0845 226 9452 Email: sales@paltronix.com Web: www.paltronix.com .■ftiSfcr-L'-vti Abesirfr vtsa VfSA EleCErOri All major credit and debit cards accepted INFO & MARKET ELECTRONICS EXPERIMENTING Learn Young... Electronics lab kits Harry Baggen Most of our readers can doubtless still remember how they first learned about electronics. What could be nicer for an electronics enthusiast than to help his or her children take their first steps into the world of electronics? Electronics lab kits let children of all ages experiment with electronics to their heart's content. A good way to get started with electronics is to buy an elec- tronics lab kit. These kits usually have boards that make it easy to interconnect various electronic components, and many of them have components fitted to a front panel. Small springs attached to the terminals of the components can be used to connect them together using various lengths of insu- lated wire included in the kit. The stripped ends of the wires can be clamped between the turns of the springs. Most kits can be used to build several different circuits, and the number of circuits is often indicated in the name of the kit, such as '1 30-in-l Electronics Lab Kit'. The size and price of the kit is generally proportional to the number of circuits that can be built with it. Relatively large kits let you use individual components placed in a breadboard area in addition to the fixed com- ponents. This gives you more of a feeling of actually putting together a circuit, and it considerably increases your free- dom to modify the circuits on your own. Some kits also have a selection of control elements, such as linear and rotary controls. This makes the controls a lot more realistic for young users and thus more interesting. After all, most of the components are 'black boxes' for be- ginners, even of their operation is described in the user's guide. The kits described in this overview can be divided into two groups: Maxitronix kits and Kosmos kits. This seems to cov- er most of the commercially available kits; we omitted kits specifically made for school use from consideration here, although some are listed in the table. Kits from the Chinese company Maxitronix are sold all over the world under various names and descriptions. The small- er kits in this family are remarkably simple. They have a base panel made from cardboard with a thickness of sev- eral millimetres, with the components and spiral springs at- tached to this panel. The edges are plastic, and the bottom covering is also made from cardboard. In some cases it is quite thin and held in place with a bit of adhesive tape. You shouldn't expect much luxury here, but the prices are rela- tively low — you can buy a kit that will give you hours of pleasant experimenting for just a few dozen quid. The larg- 40 elektor - 12/2007 Practical test Besides the assessment of the various kits by our editorial staff, we also had several youngsters perform a 'field test' with a couple of kits. The following are some of the characteristic responses. Guy (age 1 5) Tested: Electronic XN1000 • The introduction and explanation in the user's guide make a childish impression. I already feel too old for them. • Some of the words used in the explanations are much too difficult. • Assembly is nice and easy. • The components don't always match the des- criptions, and the wire colours are sometimes not the same. • Most of the experiments work right away, but if something doesn't work, there aren't any instructions on how find the problem. • It is not always clear what results you should expect from the circuit. • It's actually an interesting lab kit! Frits (11) and Luuk(12) Tested: Electronic Lab 30 in 1 • It's all pretty difficult at first, and you need some explanations from an adult. • The kit looks inte- resting, and it's very 'technical' with all those parts and springs. (For comparison, they were given a Kosmos kit to look at, but they found its appearance not at all interesting.) • Putting together the circuits is easy, and al- most all of the experi- ments work right away. • It's fun to fit the wires according to the wi- ring diagram and then see whether the circuit does something, but we don't find the explana- tions in the user's guide interesting. • You actually find out something about electricity with this; at school you don't learn anything about it. • I wouldn't buy it myself; I'd rather spend the money on so- mething else. And once you have done all the experiments, you won't use the kit any more (however, they would like to have a kit like this as a gift). er kits from Maxitronix (such as the '300-in- 1 ' kit) make a more mature impression. Here the entire box is made from plastic, and you are not limited to using fixed components and springs. The circuits are largely built on a breadboard area in the middle of the box. A completely different approach is used with the kits from the German manufacturer Kosmos. The kit box consists of two hinged plastic sections, with room inside to store the components. The breadboard area consists of little tubes with spring tabs inside. The user can insert them (once only) into small holes in the kit box. Each tube has four holes into which component leads or interconnecting wires can be inserted. A sort of jig is located at the edge of the box for bending the leads of the included components and wires to the right length. Depending on the size of the kit system, the kit includes one box or two boxes that can be fitted to- gether. Everything looks very 'technical', and it arouses an interest in experimenting. For whom? The relatively small kits are quite suitable for familiarising children with electronic circuits. To start off and see whether a child is actually interested in kits of this sort, it is good idea to buy one of the radio kits. They cost next to nothing (less than 1 0 pounds), and they provide a lot of hobby fun. After this, you can move up to a kit such as the 300-in-l Electronic Lab or the Electronic XN1 000. The larger kits from Maxitro- nix and Kosmos are most suitable for a budding enthusiast aged 15 or older who is seriously interested in electronics. In particular, the models with a breadboard area are handy for more advanced experiments because you can use them to build any desired circuit and you are not restricted to the projects or circuits described in the users guide. All of the Ko- smos kits use this approach, although the breadboard area of the smallest kit (XN 1 000) is rather small. In any case, you should certainly buy an electronics lab kit for your children, because they’re never too young to start learning. Maybe it will be the start of a fascinating hobby, or even a career in electronics! ( 060338 - 1 ) 12/2007 - elektor 41 INFO & MARKET ELECTRONICS EXPERIMENTING Electronic AM crystal radio (approx. £ 7 (€ 9); 10 years and above) A simple little kit for building only one project: a medium- wave (MW) crystal receiver. In contrast to the larger Max- itronix kits, here you have to assemble everything yourself, which means inserting the spiral springs in the holes, etc. After this, you connect lengths of wire between the springs as with the other Maxitronix kits. The special feature of this crystal receiver is of course that no battery is necessary. It draws its energy from the radio sig- nal, which is natural- ly a spe- cial expe- rience for beginners. Electronic lab kit - AM/FM radio (approx. £ 1 1 (€14); 10 years and above) The second simple kit contains a more elaborate radio re- ceiver suitable for medium-wave and VHF FM band signals. A fully assembled and aligned module is provided for FM reception. Here again you first have to attach all the springs and com- ponents to the base panel and then fit lengths of wire between the spiral springs to make the interconnections. A ear bud is used for signal output. This radio needs a source of power (in the form of a 9-V battery) because it included several transistors. A nice starter kit at a low price. Electronic Lab 30 in 1 (approx. £ 1 9 (€ 25); 1 0 years and above) put together specific projects. The initial projects are very simple, such as con- necting the LED to the battery via a resistor. There are lots of circuits that generate sound, and the ubiquitous crystal radio circuit is also included. A miniature radio transmitter is also described. It's a bit of a pity that many of the circuits use the audio transformer, be- cause this it makes it fairly difficult to understand how they work. The user's guide has an inconvenient format with a glued back that prevents it from lying flat. In light of the price, this is a fairly nice kit for beginners. Electronic Lab 130 in 1 (approx. £ 45 (€ 60); 1 0 years and above) The sample kit we received includes a user’s guide in Eng- lish and French. This shouldn’t present any problems, al- though we doubt that your average 1 0-year-old will be able to do much with the French text. The construction is the same as with the previously mentioned kit, but the board is a good deal larger and there are more components on it. The most important additions are a loudspeaker, a 7-seg- ment LED display, a slide switch, a potentiometer with knob, a CdS photocell, a dual opamp, and an 1C with four NAND gates. The user's guide is generously dimensioned, and the descriptions are clearly worded. The projects are more so- phisticated than the ones in the 30-in-l kit, and beginners will find them relatively difficult to understand. For them, it would be better to start with the 30-in-l kit and so acquire some experience with it before moving to the 1 30-in-l kit. The projects in the 1 30-in-l kit are divided into the follow- ing categories: entertainment, basic circuits, experiment- ing with the 7-segment display, digital circuits, oscillator circuits, opamp circuits, various radio designs, and test & measurement circuits. A nice kit with a large variety of circuits, but better suited to hobbyists who already have some experience. This kit contains a base panel with components that can be used to build 30 different circuits. They include a fer- rite-rod with a coil, a variable capacitor, several resistors and capacitors, two transistors, a diode and an LED, an audio transformer, a pushbutton, and a battery. The user's guide provides brief explanations of the operation of the various components, after which it gets down to business with connecting wires between the springs on the board to Electronic Lab 30 in 1 (approx. £75 (€ 100); 10 years and above) This kit has a different construction consisting of a plastic box containing various components with the familiar spiral springs. They include pushbuttons, potentiometers, a loud- 42 elektor - 12/2007 speaker, LEDs, a 7-seg- ment display, a ferrite antenna, an audio trans- former, a switch, and a CdS cell. A breadboard area for building circuits is located in the middle, and the included components can be placed on the breadboard. The components are located in several compartments so they can by stored in an orderly manner after you are finished with experimenting. The user's guide is quite large, as you can imagine with so many different circuits, and it is written in three languages. Here again the projects are divided into several categories. Thanks to the breadboard, with this kit you have more of a feeling that you are actually building a circuit, which is something that you miss a bit with the simpler kits. This is a very nice kit with lots of possibilities for anyone with a serious interest in electronics. You can also easily create your own designs on the breadboard. Electronic Lab 500 in 1 (approx. £300 (€ 400); 10 years and above) This kit is available from various Internet shops. One of its special features is that it includes a breadboard with a mi- crocontroller, which certainly opens up a lot of possibilities. The kit is built in the form of a suit- case box, with both halves complete- ly filled with ba- sic com- ponents and con- nector springs. Several bags of loose components are also included. They can be used to put together circuits on the breadboard included with the kit. Beside the analogue and digital projects included with the smaller kits, with this kit you can expand your knowledge of computer technology. It even has an LCD module and a keyboard for entering programs. Everything is explained in three user's guides - two for the hardware and one that deals with generating programs. The described projects range from super-simple to quite complicated. Even hobby- ists with a fair amount of experience can make good use of this kit, and you can build very interesting circuits with it. The software portion provides an excellent introduction to programming in machine language. Electronic XN1000 (approx. £ 45 (€ 58); 8 years and above) The approach taken with this kit from the German manu- facturer Kosmos is completely different from the Maxitronix kits. The base panel consists of two plastic parts that must be partially assembled by the user. They are hinged to- gether so the inside space can be used to store the battery, wires and components. You have to assemble the bread- board area yourself using miniature spring-steel tubes that are fitted in openings in the upper panel. Pre-stripped wires of various lengths are included. They must be bent to fit the hole spacing of the bread- board. The component leads also have to be bent to size. A sort of bending jig is provided on the box to make this easier. The projects are de- scribed in story form. This is doubtless nice for small children, but older children will probably find the story form irritating. In addition, a lot of difficult terms are used, despite the generally playful approach. The attractive appearance and design of this basic kit with 100 projects will encourage anyone with an inter- est in technology to start experimenting. A well-conceived product. Electronic XN2000 (approx. £85 (€ 110); 8 years and above) This kit consists of two boxes (four half boxes) that can be fitted together to form a quite substantial system for experi- menting with electronics. It supports a total of 236 differ- 12/2007 - elektor 43 INFO & MARKET ELECTRONICS EXPERIMENTING ent projects, although the number of components is very limited. Compared with the XN1000 kit, it has eight more passive components, a phototransistor, and an amplifier 1C. Most of the additional scope is in the second box, which houses a loudspeaker and a potentiometer. The additional projects that can be built using this kit make extensive use of the opamp for driving the loudspeaker or an LED. Sev- eral relatively elaborate radio receivers are described. The style of the descriptions is the same as with the basic kit - here again, a group of fantasy figures guide you through the projects. This is a very nice experimenting system with a good vari- ety of circuits. Electronic XN3000 (approx. £ 125 (€ 165); 8 years and above) This is the largest electronics lab kit from Kosmos, and the basic part consists of the same two plastic boxes as in the XN2000 system. An expansion set with additional spring clips, knobs, components, and even a genuine moving-coil meter increases the range of options. The additional com- ponents include a humidity sensor, a type 555 timer 1C, a counter 1C (4024), and a quad opamp (LM324). In contrast to the smaller kits, the user's guide is written in a completely different style. It is oriented to more mature 'future electronics specialists'. The explanations of how the various components and circuits work are also more extensive and detailed. For anyone who is genuinely in- terested in electronics and already has some experience, this kit provides a good guide to learning more about this fascinating subject. More kits (not just for kids) Product Supplier/Manufacturer Website price (rrp) ELI 301 electronic lab kit 130 in 1 Velleman www.velleman.be distributor(s) EL3001 electronic lab kit - 300 in 1 Velleman www.velleman.be distributor(s) EL301 electronic lab kit - 30 in 1 Velleman www.velleman.be distributor(s) Explorer, Primary (Plus), Secondary Cambrigde Brainbox www.cambridgebrainbox.com £ 13-42 Electronics, grade 6-8 Foss www.delta-education.com/science/ foss/index.shtml for schools Locktronics Kits Locktronics www.tqlocktronics.com for schools Switch On! Science Kit http://sciencekitinternational.com Mr. Circuit Lab nr. 1, II en III Electronix Express www.elexp.com US$ 26-62 Plugnlearn Graymark Int. www.graymarkint.com US$ 495 Introducing Electronics Technology Techsoft www.techsoft.co.nz for schools CD Electro Lab Omnitron Electronics www.omnitronelectronics.net $ 30 Radio and Electronics Lab Omnitron Electronics www.omnitronelectronics.net $ 30 200 in 1 Electronic Projects Lab Kit Quasar Electronics www.quasarelectronics.com £45 500 in 1 Electronic Projects Lab Kit Quasar Electronics www.quasarelectronics.com £ 150 Snap circuit boards SC-300; SC-500 Elenco http://www.elenco.com/ U$ 100$; $ 150 50-in- 1 Electr. playground EP50 Elenco http://www.elenco.com/ U$ 25 75-in- 1 Electronics lab MX- 905 Elenco http://www.elenco.com/ U$ 34 1 30-in - 1 Electronics lab MX- 906 Elenco http://www.elenco.com/ US$ 51 200-in-l Electronics lab MX- 907 Elenco http://www.elenco.com/ US$ 67 300-in-l Electronics lab MX- 908 ( = EL3001 ) Elenco http://www.elenco.com/ US$ 81 500-in- 1 Electronics lab MX- 909 Elenco http://www.elenco.com/ US$ 203 44 elektor - 12/2007 Elektor? Fun in finding solutions for my electronics hobby. Never failed to impress my boss or my wife.” - Thomas Gosling, 38, electronics enthusiast - TL Electronics at all the right levels Xo Secure a head start in electronics with a subscription! Advantages to subscribers: Cheaper than 1 1 issues from the newsstand www.elektor.com/subs Tel. +44 (0) 20 8261 4509 Subscribers get up to 40% discount on special Elektor products As a welcome gift you get a free 1GB MP3 player xA/nrth Q QA RC\ worth £ 34.50 No queues, travelling, parking fees or ‘sold out’ Elektor is supplied to your doorstep every month Always up to date - read your copy before everyone else f^llektor L electronics worldwide i-TRIXX collection Assorted smell circuits in a free supplement with Elektor magazine For the second year round-) we have gathered a varied collection of simple but useful and sometimes downright cute electronic circuits that you can build yourself-) so that there’s no excuse for being bored to death during the long winter evenings that are upon us* The EDQh i-ITRIXX supplement was generally well received in terms of its educational value-) contents and presentation-) both by old hands at electronics and newcomers to the Elektor publication- The success story is continued this year- Although the present i-TRIXX collection is again aimed at those of you starting out in electronics-) or on a modest budget-) scavenging components from the junk box-) we know that the circuits presented also have an appeal if you just want to make something quickly in an afternoon or so- All projects are based on easy to obtain components or items normally thrown away as useless just because they are not state of the art (compared to l what the neighbours have 1 )- An i-TRIXX project is never complicated! big or difficult to understand-) we hope! Plus-) it can be soldered together in a spare hour or so- This free supplement contains a large selection of these types of circuits-) pulled from the Elektor lab and from our large circle of free-lance contributing authors- If you would like to contri- bute to next year’s l doseS please let me know- III ch pleasant soldering! £ oc < 1=3 S 3 [ Jan ^ U1 £cJit of ~ roW Christmas flasher p4 P? I li- st beeper for your stereo ■i III Light dimmer for torches pR I (rararaftog -canary pl4 ’ent a detector pl£ made battery pEE Silent dog whistle P17 Sensitive torch (C) ELEKTOiy (C) ELEKTi 01003 Christmas flasher Have you already brought a Christmas tree into the house and decorated it with lights according to ancient Germanic custom? Improve the atmosphere some more by making one or more of your own Christmas decorations- Colourful light emitting diodes (LEDs) flashing in an apparently random order and speed provide a festive scene. Building this is a piece of cake because of a complete kit containing all the necessary parts, including the circuit board. This kit can be ordered via the Elektor website for a fay The circuit for the Christmas flasher is quite a simple design. A digital counter 5\ /C\ 3 / \S / which is set with resistor R1 and capacitor Cl. With the values shown here this frequency is about 5 kHz. This oscillator signal is divided using various ratios by the internal digital electronics. These divisors are indicated with the letters CT on the 1C symbol. So, for example, on output CT3 (pin 7) there will be ^1 square wave with a frequency of 5 kHz divided by 2 3 , that is 5 kHz / 8 = 625 Hz. • • CT4 divides the oscillator frequency by 2 4 = 16, CT 5 by 2 5 = 32, etc. That means all these outputs toggle at their own rate. The LEDs are connected in three groups between six of the counter \ - . outputs, resulting in 11 LEDs flashing with a seemingly arbitrary pattern. The 1C socket (note the marking!), both resistors, the capacitor and the i kS battery clip are soldered on the triangular circuit board first. The eleven • • the cathode. After a final inspection the Christmas flasher can be connected to a 9- Volt battery. A festive winking should be the result! 010032 C) ELEKTOR 010032 ht CTR14 ■ ■ In R1 (> — | 10k I R2 I — | 100k | — I D1 D2 D3 D4 D5 D6 D7 D8 D9 DIO Dll CT < RCX 12 CT=0 4060 i-TRIXX collection Water alarm Have you ever witnessed the stairs to a higher floor trans- formed into a genuine waterfall? Or that the fishi next to the aquariumi are practising swim- ming on dry land? No? Vou cer- tainly wouldr^t want to-« because the mess is incomprehensible- LJi th a handful of electronics you can ensure that you are warned before things get too damp- Flooding is better prevented than remedied! But despite the best precautions it is regrettable that sometimes it is possible that something will leak. A broken water hose to the washing machine, a forgotten bath tap, a broken aquarium window or a leaking boiler, any of these could happen. In any of these cases it is useful that you are warned as soon as possible, for example by means of an acoustic water alarm. That way you can at least attempt to limit the amount of damage. This circuit uses the fact that 'ordinary' water is always, ever so slightly, polluted and therefore conducts current to a certain extent. This circuit is built around a popular 1C from the old 4000 series logic: the 4093. This 1C contains four inverting AND gates (NANDs) with so-called Schmitt trigger inputs. When water is detected between the sensors an intermittent and somewhat irritating alarm will sound. The conducting water is used to switch ICIa on. Two electrodes (sensors) are mounted at the lowest point the water will reach. These could be two tinned, copper wires, but two pieces of circuit board with the copper surface tinned will also work. IC1 a forms, with resistor R2 and capacitor C2, a simple oscillator that generates the intermittent (on/off) effect of the alarm sound. If there is no water between the sensors, then the input of IC1 a is held low with resistor R1 and the output of IC1 b is also low. The oscillator does not operate in this state. When moisture is detected, the power supply voltage, via the sensors and conducting water will change input 1 of gate ICIa to a high level, which causes this gate to function as an oscillator. Each time the output of IC1 b is high, the tone generator built around ICIc is activated, which in turn drives buzzer BZ1. In this way a rhythmical, on/off switching beeping noise is generated. The intermittent effect of the sound produced by the water alarm can be easily adjusted to your liking by changing the values of R2 or C2. With PI you can adjust the pitch of the sound. The closer you are to the resonant frequency of buzzer BZ1 the louder the sound will be. This sound has to be adjusted to the most irritating level. Gate IC1 d is used to allow more power to be generated for the buzzer. IC1 d inverts the output signal from IC1 c and the voltage across the buzzer is therefore twice as much. The circuit itself has to be mounted in a high and dry place, of course. Connect the electrodes (sensors) with two thin, twisted wires to the circuit. Be sure to use insulated and flexible wire. By twisting the wires, the (relatively long) connection between the sensors and the circuit is less sensitive to false alarms caused by electromagnetic interference. The current consumption in the dry state is very small (less than 0.1 jiA). When the buzzer is activated the current consumption will be about 2 mA. With the frequency adjusted to the highest level we measured 3 mA. As long as no water is detected the battery will therefore last for years. However, in the long term there is a risk of leaking batteries... i-TRIXX collection ^ I ^ 5 ITl^l-rfcin iTimn Two-thirds of the higher educa- ted can be reached for work via telephone! text or email while on holiday! according to recent reports in the media- Communi- cation has become so easy be- cause of technical developments that it can be easy to feel yourself morally obliged to be available at all times- Mobile phones and notebook computers have become standard items in our travel luggage- But what was the purpose of a holiday again? Vesi exactly! to relax! And if there is no other solution! then we can use technology here also to help us with this too- 8ief eedback You know it when you are (too) busy; perspi- ration is only one of the harmless physical symptoms of psychological stress, insomnia or increased blood pressure is less harmless. If you continue to ignore these alarm signals from your body, the sources of stress can build up, and you are well on your way to mental or physical ex- haustion, with burn-out as the final consequence. A holiday can be an excellent method to take your mind off things and to interrupt the continuous state of high stress. But then you have to be able to switch off! You can train yourself in the operation of this 'switch'. The circuit presented here helps you with this. The principle of this electronic relaxer is based on biofeedback. Feedback is also a well-known concept in electronics and in particular with control technology. In this, the output signal from an amplifier is compared with the input signal so that discrepancies in the shape of the output signal (distortion) are mini- mised by the action of negative feedback. Positive feedback is also a form of feedback, but in this case the differences between the input and output signal wave shape are reinforced. Feedback is an essential feature in, for example, an oscillator (the output signal sustains itself via positive feed- back). Our body also knows how to control certain functions via biofeedback. If we are too hot we will start to perspire, which cools us off, so the amount of perspiration can reduce again. With a good biofeedback control (and fortunately this is the case most of the time) the control system is nicely in balance. Flowever, excessive or long-term stress can cause the system to become unstable (an amplifier becomes an oscillator or the other way around) and it's high time that you relax to give the system an opportunity to find its natural balance again. Electronics inside out! You can be too hot when you physically exert yourself, but is can also happen when too much is demanded from your psychological powers. If, in the latter case, you are able to relax then this can be measured electroni- cally based on the skin resistance. This re- sistance, as it happens, increases when you perspire less and the blood is less close to the surface of the skin (there is less need for cooling, after all). This phenomenon is put to good use in our electronic relaxer. It does nothing else than measure the electrical resistance between, for example your left and right hands, and translating it into a beeping sound. By relaxing yourself you lower the frequency of this sound. The circuit is built around the well-known 555 type timer 1C (or the energy saving 7555). The resistor Rx, drawn with dashed lines, represents the electrical resistance of the human body. This body is connected via two sensors. You can, for example, use two metal rings which you put around a finger of your left and right hands. The rings are connected with flexible wire to the circuit; one to R2 and the other to pin 6 of the 1C. Instead of rings you can also use metal rods of course, but holding them with unvarying pres- sure is less relaxing. Out of safety considerations, this circuit may not be con- nected to the mains (so don't use a mains power adapter). To power the circuit, only use a 4.5-V battery or three 1.5-V penlight batteries in series (optionally rechargeable). Never make the power supply volt- age higher than 6 volts (that is, 4 penlight batteries in series). Al- though this low power supply voltage is harmlessly low, we strongly advise against the use of the electronic relaxer by heart patients (in particular those with a pacemaker)! The 1C with the surrounding components have been designed such that the output results in a square wave, the frequency of which is in the audible range. Transistor T1 amplifies the signal and passes it to the little loudspeaker, which turns it into a beeping sound. The output frequency can be adjusted with PI to suit your skin resistance. Choose a sound frequency that you find pleasing. You can adjust the volume of the sound with P2. So what happens when you get tense? The skin resistance will drop and the result of that is a higher frequency sound. Now try to lower the beep frequency by relaxing yourself (think of peaceful scenes). This requires some training, of course; so do not give up too soon, and certainly do not get agitated if you fail to succeed at first. Getting wound up never serves any purpose, because it never changes any- thing to the source of the agitation and is only an obstacle to making the right decisions or thinking of good solutions. And if you under- stand that art of relaxation, then this will result in sufficient energy to survive the next period of stress intact. So plenty of practice, because practice makes relaxed! 061007-11 6 i-TRIXX collection Thirst indicator Watering house plants on time is not always an easy task for everyone- The watering can often only appears after the leaves are already looking a bit sad- Not every plant recovers from such a period of drought- With a handful of electronic parts and a spare hour you can build yourself an indicator that will give a timely indication with a flashing LED that the well-being of your house plants is in your hands- house plants An easy way to determine the moisture of the soil of a pot plant is to measure the electrical conductance of the soil with two electrodes. As the soil dries out, it becomes a poorer conductor between the two electrodes. To prevent electrolysis (decay or corrosion) of the electrodes, a pure AC voltage has to be used. The easiest way to make this AC voltage is to use a gate with a Schmitt trigger input as an oscillator. Here we used a 74HC132 (an 1C with 4 NAND gates). An oscillator (also called an astable multivibrator) has been designed around IC1 A, the frequency of which is set to about 10 kHz. Cl is charged and discharged via R1, whenever a switching threshold of the Schmitt trigger is crossed and the output of the gate changes logic state. The electrodes are connected via capacitors (C2 and C3) to the output of the oscillator and the input of the second gate (IC1 B) to make absolutely sure that the current through the electrodes is pure AC. In this way the soil of the plant conducts the signal from IC1 A to IC1 B. If the soil is sufficiently moist, the AC voltage at the second electrode is large enough to switch IC1 B at the same rate as that of the oscillator (IC1 A). The square wave output voltage of IC1 B is rectified by diode D1 and filtered by capacitor C4 so that gate IC1C has a high level on both of its inputs and therefore a low level at its output. This low level ensures that the output of gate IC1 D remains high and the indicator LED (D3) stays off. IC1 D is also wired as an oscillator. This oscillator comes alive (input pin 13 goes high) when the soil is too dry and therefore the AC voltage at the second electrode is too low. The correct level between dry and moist can be adjusted with PI, depending on the type of plant and soil, and the spacing between the electrodes. The frequency of the oscillator built around IC1 D is about 1.5 Hz. The result of this is a brightly flashing LED. D2 and R7 ensure that the LED is lit for only 20% of the period (and is therefore off for 80% of the time); it is therefore obvious when the LED is on, while at the same time the average current consumption from two 1.5-V batteries is reduced significantly. The current consumption with a flashing LED amounts to about 1.4 mA. When the LED is off it is about 0.4 mA. With two penlight batteries the circuit will operate for about 300 days (we assume a capacity of 3000 mAh), provided, of course, that the plants are always watered in good time... i-TRIXX collection Has a channel from your ste- reo failech or you donH hear anything anymore from your headphones from your MP3 player? It could be a broken wire or a bad pLug-i but also the internal electronics could have given up the ghost- With this test bee- per you can quickly find out- TL081 K1 63V 1kHz 061009-11 ff ■' t WLf C* » V* m mt 'll Jfc The test beeper presented here generates a sinusoidal signal with a frequency of 1,000 Hz, a common test frequency for audio amplifiers. The test signal can be directly connected to the input of an amplifier or via the suspect cable. You can then wiggle cables and plugs in an attempt to locate a potentially bad connection. Swapping cables around sometimes helps as well. The test beeper can also be used as a signal injector when looking for faults in amplifier stages. For this you 'inject' a test signal, for example starting at the input, directly into the amplifier and progressively move the injection point towards the output until the test signal becomes audible; the location of doom is quickly found in this way. If you are going to use the test beeper as a signal injector then it is recommenced (to prevent a potential overload of the electronics to be tested) to connect a resistor of at least 10 kohm in series with the output. •i •* The test beeper consists of a classic Wien-Bridge oscillator (also known as a Wien-Robinson oscillator). The network that determines the frequency consists here of a series connection of a resistor and capacitor (R1/C1) and a parallel connection (R2/C2), where the values of the resistors and capacitors are equal. This network behaves, at the oscillator frequency (1 kHz in this case), as two pure resistors. The opamp (IC1) ensures that the attenuation of the network (3 times) is compensated for. In principle, a gain of 3 times should have been sufficient to sustain the oscillation, but that is in theory. Because of tolerances in the values, the amplification needs to be (automatically) adjusted. Instead of an intelligent amplitude controller we went for a somewhat simpler solution. With PI, R3 and R4 you can adjust the gain to the point that oscillation just takes place. The range of PI (±10%) is large enough to cover the tolerance range. To sustain the oscillation, a gain of slightly more than 3 times is required, which would, however, cause the amplifier to clip (the 'round- trip' signal becomes increasingly larger, after all). To prevent this from happening, a resistor in series with two anti-parallel diodes (D1 and D2) are connected in parallel with the feedback (PI and R3). If the voltage increases to the point where the threshold voltage of the diodes is exceeded, then these will start to conduct slowly. The consequence of this is that the total resistance of the feedback is reduced and with it, the amplitude of the signal. So D1 and D2 provide a stabilising function. The distortion of this simple oscillator is around 0.1 % after adjustment of PI and at an output voltage of 100 mV (P2 to maximum). You can adjust the amplitude of the output signal with P2 as required for the application. The circuit is powered from a 9-V battery. Because of the low current consumption of only 2 mA the circuit will provide many hours of service. 8 i-TRIXX collection Liqht dimmer torches You can, of course, reduce the output from a torch by connecting a resistor in series with the lamp. If you select resistors with several differ- ent values you can adjust the brightness of the lamp in several steps. Such a control does not make particularly efficient use of the (recharge- able) batteries in the the torch; after all, a considerable amount of electrical energy in the form of heat is wasted in the series resistor. In particular when we, as campers, choose to pitch our tent far from the civilised world (and power points), we obviously have to be as frugal as possible with the limited energy in the batteries of our torch. This is easily done with a little electronics. Ordinary mains light dimmers also use as little energy as possible. Not only to prevent the waste of energy but also to limit the heat gen- erated by the dimmer itself. The latter is very important when dimming incandescent lamps connected to the mains, if we would like to avoid scorched wallpaper. The ubiquitous light dimmer for incandescent lamps regulates according to the on/off principle. The mains voltage is passed completely for part of the time and blocked completely for another part. This happens at the same rate as the frequency of the mains. In this type of control there is (nearly) no electrical energy lost in the form of heat. We can also make such a low- loss on/off con- trol for the DC (= battery voltage) powered torch. The controller ensures that the battery voltage is switched on and off at such a high rate that it appears to the eye that the lamp is on continuously. The lamp itself, because of the filament's slow reaction, also contributes to averaging of the on/off switching. By varying the ratio between the 'on time' and 'off time' we control the amount of light from the lamp in an energy efficient way. For the fast on/off switch we use the familiar timer 1C type 555. Specifically the CMOS ver- sion of the original NE555 is used, called TLC555 because this version uses less current. Even though this 1C has a lower output current rating this is not a problem here, because an additional output transistor is used (in this case a FET) to drive the lamp. A BS170 was chosen for this transistor, which can deal with a lamp current of 500 mA without any problems. For larger applications you will have to use a real power MOSFET such as a BUZ11 or similar. With these make sure that the battery voltage is sufficient to ensure that the MOSFET is turned on properly; some types may require more than 4 V on their gate! The 555 is configured here as a squarewave oscillator. A squarewave-shaped voltage ap- pears at the output (pin 3). Differing from the standard application is the addition of diode D1. Because of D1, two different times can now be adjusted independently. The amount of time that the output is logic High is determined by R1 and Cl and amounts to about 0.8 ms. The time the output is low is determined by R2, PI and Cl and can be adjusted with potentiometer to a value between 1.9 ms and 36 jis. The duty cycle (the ratio between on and off) can be adjusted from 30% to 96% with these part values. Dimming to less than 30% has little merit because the light output will be too low to be useful in practice. The operating principle of the circuit also causes the frequency to vary. At 30% the frequency is about 370 Hz and at 96% about 1.2 kHz. But that doesn't matter of course, both for an incandescent lamp and our eyes. The circuit is obviously powered from the bat- teries in the torch. Without a lamp the circuit, at a battery voltage of 6 V, consumes only 170 |iA and at 12 V, about 280 jiA. (If an NE555 were used instead of a TLC555 this current consumption would be considerably higher!) The low current consumption of the circuit itself can be neglected compared to the current con- sumption of the lamp and the circuit therefore has practically no influence on the life of the batteries. The fact that the maximum setting is only 96% has the pleasant side-effect that the lamp will have a much longer life expectancy. To test the circuit we used a lamp rated at 6 V/50 mA. At full brightness the voltage across the lamp was 5.66 V and current was 49.5 mA. At minimum brightness this voltage was 1.71 V with a current of 19.6 mA. Both the measured voltages are a little lower than expected from the duty cycle, but don't forget that T1 is not an ideal switch and a small voltage is lost across it. First build the circuit on a piece of prototyping board (experimenting PCB) and connect the lamp from the torch by itself. Only build the dimmer into the torch when everything works properly! First trace the connections from the batteries to the lamp and on/off switch. Be- cause it is usual for the switch and/or the lamp holder to be permanently connected with ground (the electrically conducting metal hous- ing of the torch) it can be a bit of a puzzle to obtain the correct connections with the switch. It is easier of you fit a separate miniature on/off switch in the housing for the torch and connect it in series with the batteries with two separate wires. Use a small piece of double-sided PCB that you place between the battery and the ground spring (if there is more than one battery in the torch you can place the PCB between two batteries; it doesn't matter between which, as long as it ends up in series with the batteries). Solder the wires to each of the copper surfaces (i.e. those that are electrically separated from each other). Both wires are now connected to the new on/off switch. Now connect the lamp - . from the torch to the circuit. Make sure there ■ are no electrical connections between the lamp holder and the other parts of the torch (change the mounting of this holder if necessary) and connect the lamp with two wires to transistor T1 and the positive of the battery (or the series connected batteries). Use a miniature version for the potentiometer (PI) and mount it in a convenient place and connect this to the circuit with two wires as well. Once you've connected everything cor- rectly you can adjust the light output from the torch between mood light and search light. Y i-TRIXX collection 9 In dark pUc« in particular, .n rzx ~ , building- With only one ICi lfi LE1> shows the correct direction in the form of build a prominent indicator that i miss fche door t0 your house party-, running LED arrows- In this way no / and afterwards-, the outside door- •ft * * ft * ' ft * « * • « » * To indicate direction you could obviously just use an illuminated arrow or a flashing light, but it is much nicer of course if something moves in the correct direction. The idea, here developed into a circuit, was born when we saw and older circuit with a few LEDs in the shape of an arrow. The LEDs were driven as a running light with two ICs; a clock generator and a shift register. We immediately thought that this was a nice idea, but it should be simpler than that. And that that is indeed possible is shown by this circuit. Only three inverters with Schmitt-trigger inputs are used. That is only half of a 74HC14. The other three inverters (ICI D to ICI F) are, to prevent noise on open inputs, connected to fixed input voltages by connecting them in series with the first input connected to the power supply voltage. The inverters behave as level-changing switches (a High level appears on the output as a Low level), while the Schmitt-trigger behaviour ensures a clean switching transition. The clock signal (the pacemaker for the running effect) is, just as with a standard oscillator, generated with a Schmitt- trigger inverter (ICI A), but instead of feeding back its own output, feedback is now connected to the output of the third (ICI C) of the three in series connected inverters. The output signal used for the feedback signal has the be of opposite phase, of course. Six series connections of three LEDs each (arranged in the shape of arrows) are connected to the outputs, or more accurately, between the outputs of the inverters in such a way that only two of the six columns (arrow points) are lit with two extinguished columns in between. Each time the lit arrows move over by one column, so that it appears that the arrows run from right to left. * * * * » * • # • Once the circuit has been built, you can experiment with the clock speed if you like. This has an influence in the perception of the running effect. With a slightly shorter time (lower value for Cl to C3 or R1 to R3) the circuit appears to become a collection of flashing LEDs. Depending on your personal preference, another timing may be required. Build the circuit with red LEDs of the high- efficiency type. With 9 columns the circuit does not quite draw 6 mA. This is quite easy to calculate, because the current for each column of LEDs is set to just under 2 mA, and 3 columns are turned on each time. If only 8 columns are connected then the average current consumption will be a little lower. The low current consumption of the circuit makes it possible to power it from batteries. Recent alkaline AA batteries often have a capacity of 2800 mAh. With four AA batteries in series (and therefore generate a power supply voltage of 6 V) the circuit will run continuously for nearly 20 days. In a permanent installation a modern switch-mode mains adaptor is preferable for the power supply. m To make the arrow longer than the six columns drawn in the schematic, the additional columns are connected in the same order as the first. So the seventh column is connected in parallel with the first column (D16, D17 and D18), the eighth column in parallel with the second column (D13, D14 and D15), etc. Keep the number of columns limited to 15; more columns are too high a load for the inverters. 10 i-TRIXX collection BC517 ft _IL S 1 T. o CO CO Cl II 1 C2 l II l C3 , II „ 11 ^ 1 II * ’ II " 47n lOn 3n3 R1 R2 061013-11 Electronic drumming tightly stretched skin- This vibrate which then sounds like music- The sound of a drum is generated when a stick or hand hits a skin causes the surrounding air to After the strong strike (attack) that brings the skin in motion, the sinusoidal vibration dies away slowly (decay). This wave shape can also be generated elec- tronically by driving a loudspeaker with a suitable cir- cuit. Such a circuit is shown here. It concerns a simple phase-shift oscillator. This oscil- lator generates a nice sinusoidal signal. The resis- tors R1, R2 and R3, the capacitors Cl, C2 and C3 and coupled to this network the resistors R4 (when SI is pressed) and R5 and capacitor C4 ensure that the si- nusoidal signal at the collector of T1 is changed in phase by exactly 180° and gets fed back to the base of T1. The signal at the collector is again phase shifted by 180° with respect to the base voltage so that the total phase shift is 0° and the circuit will oscillate when there is sufficient gain (which is the case here). When you press push button SI, the oscillator gener- ates a continuous sinusoidal signal, provided the gain is set correctly with PI. This gain has to be just right so that the oscillator just continuous to oscillate and does not decay. When SI is released the oscillator will stop. Checking the oscillator is obviously the easiest (that is, without measuring instruments) by connect- ing the output to the input of your sound system. Take into account the fact that the circuit has an output signal of several volts, so start by setting the volume of the sound system to a low level (this saves speak- ers and ears). So, by pressing switch SI you strike the electronic drum. The pitch is determined by the oscillator fre- quency. With the component values shown in the schematic this frequency is around 240 Hz. Our drum sounds like a marimba that is being played with soft sticks. If you would like to change the frequency and therefore the sound of the drum you need to change the values of Cl, C2 and C3 up or down by the same ratio (higher values result in a lower frequency). You can also experiment with the value of capacitor C4 and resistor R4. For a slower decay, increase C4 and reduce R4 in the same proportion. When R4 is ratiometrically reduced even further this increases the attack of the oscillator and changes the sound to more that of a drum. Don't forget to adjust the gain again to its optimum setting. The electronic drum draws about 4 mA of power supply current whenever it is struck. When SI is not pressed the circuit draws practically no current: a sep- arate on/off switch is therefore not necessary. You can use a 9-V battery for the power supply. In the accompanying photograph you can see a piece of prototyping board we used the build the electronic drum. At the bottom left of the board you can see two sockets; this makes experimenting with different resistor or capacitor values much easier than repeat- edly soldering and de-soldering! If you would like to build multiple drums of differ- ent pitch, then you obviously need a correspondingly larger circuit board. Positions the switches, for exam- ple, in such a way you can play them without moving your hand. Use microswitches that require a low force to operate and if necessary glue a larger striking sur- face to each switch. The drum in earlier times was not only used as musical instrument! but also (if weVe to believe the L Indian stories 1 ---) as a communications device to transfer messages quickly over large distanc- es- Such communi- cations go much simpler these days! you donH have to follow a difficult course in L message drumming 1 and in addition you can send your message (if the servers de- cide to co-operate a little) around the world in mere moments! sometimes to the annoyance of those who didnH ask for it- In the current electronic age an electronic drum is more ap- propriate! not as a communication device any more! but solely as a musical instrument- k) iV SI i-TRIXX collection 11 u Vour time starts now ! 11 This is a phrase that is often heard preceding a contestants turn in an exciting game show- An electronic timer serves as an aid to give each player an equal chance- With some games played around the table at homei such a timer can also avoid heated arguments- An i-TRIXX reader who apparently was keen to maintain good relations within his family asked us for a design of an easy to build game ti Tine for a The reader asked for a timer to be used with the game Rum- mikub. The circuit has to give some sort of indication when 1 or 2 minutes have elapsed. We started with this design brief, but the circuit is easily adapted if different times are required. For the heart of this circuit we chose an 1C that has been used in earlier i-TRIXX circuits, the type 4060. This 1C makes it easy to generate extremely long times that can be set accurately. An LED (D2, a low-current type) is used to indicate that the timer is running and the power is switched on. A buzzer (BZ1) sounds when the game time is over. mer- Cur Elektor lab got busy- game? counter will not reach its maximum value. When the switch S2 is in the '2 minutes' position, the counter will stop itself (via diode D1) the moment that output CT9 becomes high (logic 1). At the same time, transistor TI (which serves as a buffer) will activate the buzzer. That obviously happens exactly 2 minutes after pressing the start button (SI). If switch S2 is in the other position then the buzzer will sound after 1 minute. Should the time not be quite right then it can be accurately adjusted with potentiometer PI and comparing it with a stopwatch or the seconds hand of a clock or watch. Just a short explanation about the operation of the 1C, a so- called binary counter with an internal clock oscillator. At its CT outputs there is a digital pattern of zeros and ones. At first all outputs are zero. It then runs through all the digital coun- ter values (and that are quite a few with this 14-bit counter, 16,384 to be exact). This happens at a rate set by the RC net- work connected to pins 9 to 11. Since the indicator LED (D2) is connected to the internal clock oscillator, it flashes at the same rate of about 4 Hz. The way the 1C is used in this circuit, the We deliberately kept the circuit as simple as possible (no ad- ditional power-on-reset network). So it is possible that when the circuit is first switched on, some arbitrary time between 0 and 1 or 2 minutes will elapse before the buzzer sounds. How- ever, after pressing the start button (reset) the timer will run for the correct length of time. Incidentally, the length of time that the start button is held down has no influence on the selected time. If you would like to be able to stop the timer before the time is up you can consider connecting SI with the positive power supply instead of pin 12 of the 1C. The counter will now be reset whenever S2 is pressed. Once you release the button the timer starts to run. Besides Rummikub, the timer can of course be used with other games and applications that require an indication after a prede- termined amount of time. The time can be shortened by a factor of 2 to half a minute by connecting output CT7 (pin 14) instead of output CT8; or lengthened by a factor of 4 from 2 minutes to 8 minutes by connecting output CT11 (pin 1) instead of out- put CT9 to switch S2. Note that the 1C does not have an output CT10; lengthening the time from 2 to 4 minutes (factor of 2) is therefore not possible. If you need that length of time, then it is necessary to double the value of resistor R1 or capacitor Cl. If you would like more than two different timer values then you can substitute a switch with more positions for S2 and connect its contacts to the desired CT outputs. The current consumption of the timer - when running - is de- termined mainly by the flashing LED and mounts to less than 1 mA. The current consumption is obviously considerably high- er when the buzzer is on. With the prototype we built, it was about 16 mA. For the beeper (buzzer) we used a round, axial, 12-V version. Electronics inside out! A A complete solution: robot + software + curriculum Line following and maze solving High-tech specifications Also programmable with C or ASM E-blocks compatible Motivating for education and hobby lektor electronics worldwide Elektor Regus Brentford 1 000 Great West Road Brentford TW8 9HH United Kingdom Tel. +44 20 8261 4509 Order quickly and safe through www.elektor.com/shop + W? Pets are nicei they provide pleasant companionship- Especially for those living alone-i and those in nursing homes-i a pet can provide a welcome relief from the mundane of daily routine- It is less pleasant when pets die-i not a single specimen exempted- They tend to do that sooner if theyVe not looked after- Forgotten to feed the dog or the cat? Chi they will definitely let you knowi but the canary will sit there quietly until he drops off his perch- The chip-canaryi built from electronics! will be spared this grief- The silicon canary described here (Serinus canarius siliconis) is fed with batteries. An empty battery just means that the cheerful chirping stops; a fresh specimen will bring it back to 'life'. In this way feelings of guilt on the part of the owner are avoided. — 1 ,wtr P The heart of this canary is formed by a chip, or more specifically, an 1C type 4093, a quad NAND-Schmitt-trigger. This 1C has already been used in other i-TRIXX circuits. With NAND-gates you can very easily build different types of oscillators. That is the case here as well. Cl Birds have a syrinx at the lower part of their throat, a vocal organ whose shape is changed by muscles and in this way produces different sounds. The syrinx is here emulated with three oscillators, built around gates IC1. A, -B and -D. Each oscillator provides its own part of the canary song. The individual oscillator wave shapes are combined by the surrounding components and produces an output signal that, when acoustically reproduced by piezo buzzer (Bzl), sounds quite similar to the cheerful chirping of a real, live canary. The oscillators . obviously have to be properly tuned by ear first. Adjust potentiometers P2, P3 and P4 so the song from the chip-canary best resembles a real one. With three presets it takes a little while to obtain the closest true-to-life setting. P4 is used to move the entire frequency range up or down. P2 and P3 are then adjusted so that a realistic chirping can be heard. The get this electronic canary to sing, it is enough to push switch S2. Depending on the setting of potentiometer PI he will sing for a certain amount of time. Feed this canary with a 9-volt battery. To prevent the canary from eating the whole battery, you can turn the power supply ! voltage off with SI. ► 4x ' 1N4148 1N4148 PB2720 070052-11 Electronics inside out ! i-TRIXX collection b in 10V wervuus spiral Ner ho hasnH seen one of these-* or perhaps in this century we should ask: who still has one of thesei that nerve-racking but exciting game where you have to move a metal ring along a twistedi metal wire to an endpoint without two making electrical contact with each other? This requires a steady d nerves of steel- i-TRIXX helps you build an electronic referee s gamei which not only verifies whether the finish line has been ached-i but also places a time limit on the duration of the game- When playing this game you literally have to become a contortionist. The skill is to move the ring as quickly as possible along the twisted wire from beginning to end. The ring is obviously not allowed to touch the wire along its path, because this is punished immediately with the sound of the buzzer to indicate that you have forfeited your turn. Dawdling too much will also end you attempt. We have attempted to keep the electronic part of the game as simple as possible. So we haven't used, for example, and on/off switch; in the idle state the current consumption is negligibly small. The circuit comes alive when pressing the start button (SI). The circuit consists of only one 1C (a 4538) that contains two timers. The first timer (IC1 A) drives the buzzer for a limited amount of time, so that it does not continue to beep unnecessarily and irritate other players and spectators. We choose a duration of 10 seconds. This also reduces the current consumption of the circuit and since the power supply is provided by a 9-V battery this is a nice benefit. Because the outputs from the 1C cannot deliver sufficient current to drive the buzzer directly, T1 is connected to the output of IC1 A to act as a buffer. The second timer IC2B determines to amount of time allotted to carry out your task. This time can be adjusted from 22 seconds to 2 minutes with the aid of PI. An LED (D1) is lit for the duration of your turn. The timing durations for both the first as well as the second timer are easily changed to suit your needs. The duration is determined by and RC network connected to pins 1 and 2 of IC1A and pins 14 and 15 of IC1B. The length of time that the outputs of the timers are active is equal to R x C. For example, for IC1 A the time is: 1 MQ x 10 jliF = 1 x 10 6 x 10 x 10 6 = 10 seconds. It is as easy as that! Always use good quality electrolytic capacitors (that means high leakage resistance) for Cl and C2. E The sensor (the ring) is connected to the positive trigger input (pin 4) of the first timer. Output pin 6 of the first timer goes High (= 9 volts) when pin 4 goes from Low (= 0 volts) to High, that is, when the ring touches the wire. The buzzer is driven via T1 and sounds the signal that the 'attempt has failed'. Pin 5 of this timer works the other way around; a low level starts the buzzer. This is used to drive the buzzer (the LED turns off) when the maximum game time (pin 10 of IC1 B goes low) has elapsed. When you press SI, the first timer is reset and the second timer is started. Pin 6 of IC1A is now low and pin 10 of IC1B is high, with the result that the buzzer is silent and LED D1 is lit to indicate that the game is in progress. If the game time elapses before the player has reached the finish line, then the second timer will activate the buzzer and turn the LED off. I I If the finish is reached within the allotted time, it is not necessary to wait until the time is up to start a new game. As soon as SI is pressed the timers are back at their initial positions and a new game has started. The circuit draws practically no current when the LED and buzzer are off. We measured less than 0.4 juA With only the LED on the current consumption amounts to slightly less than 2 mA. When the buzzer is activate and the sensor is connected with the wire (9 V) the current consump- tion is the greatest and that was a little over 17 mA in our prototype. We used a low-cur- rent type for the LED, which is quite bright at only 2 mA. The minimum voltage is mainly determined by the buzzer and our prototype continued to work when the power supply voltage was down to 4.4 V! The LED, however, was only dimly lit. To save on battery power it is possible to shorten the amount of time that the buzzer is on some more. It is best to build the circuit into the enclosure that also supports the twisted metal wire. The beginning (start) and end (finish) of the wire is fitted with a small amount of insu- lation (electrical tape or sleeving, for example); the ring can then be parked without activating the circuit. Internally you connect the twisted wire with the positive terminal of the battery (which is also connected to the circuit). The metal ring is con- nected with a flexible (insulated) wire to the sensor input of the circuit (pin 4 of IC1 A). Now you can check whether you possess a steady hand and nerves of steel. T ' 061015-12 15 Tent alarm It is quite difficult these days to protect a house from unwi come guests-i not to mention a tent! However-i with a little bi of electronics it is possible to protect a tent reasonably wi T4_ is of course not possible to complete lij m breaking into a tent with an electr r «. w r i i i w i ' i > i i m . a i i r l it nr UlOixCI I . * 1 1 the process of wrong- when the circuit at points A and B (see fully appropriating is connected to the 4093 This other peopled prop- schematic). , sinale digital \C, type . . t ■r‘r alarm i Sl of )C contains a set of tou is on ly 'logic 0 (- 0v ° ) he output coursei also such a NAND gate is tha f 1 v0 | tage ); in all oth aroun d handy when of the inputs are 'logic l- P°* e ^ square wave oscillate' rs are d camping in, for is lays 'logic V. Using hfP^two ..scillatoR is to generate an .n example! the t irix and IC1.D. The task , : s armed with North-Ameri- q ■ sound. h oscillator using gate IC1.D. When the ^ ^ con nected to can wilder- ^ e 9 xplain the ope ra ^n° f .h conducting wire ensures tha P ^ gate stays at logic n * SS switch SI, the still intact and elect ' Y , ts) As a result the outp t p1 10 a logic 1 prevent a SW „ " 1 'ate IC1 .D is at a 'logic 0 level t whi | e ) via resistor R2 ana grizzly P m tn ,,t will charge capacitor Cl (a , Nothing else happen . » . because of resistor you un- This sta ^^j[)-gate arc 9 1{ . p r ^hc input ^t P ^ + thp transition from t iris? « ?;r .0^:^ bag - inverted version 0, the , 'eampi»9-P-o»'' ' n jS i« e“»n«re».. Mi«s. the , small plug and sockj - The Tonld stretch the thm »«' a '“" V,° 10 nr you- tent so that te»< I,™” « nave enough time to flee up a <*- • m the event of an aiaru y ran) Electronics inside out ! 06A0A7 - tA AOOVc 16 or perhaP s b ®^ 0 wn« rS Vou see **. to expressedt V to0 late pan io* who d ® c i e tr%^ faitV ' rream their teach thexr The y s‘ r *“ cll s a «i to S « s out when W* time being lun9 nff and, f° r its owner- * run ,_ r atur^ ever ot,n® r aS. -ri^SHs x&r ln9 response co lot 0 f for ccompanie whe n uSins , eC tronit & -5 ic p * y^anctui. O Canis lupus familiaris, the dog that is, possesses excel- lent hearing. Even though you may not suspect that when Fido, at the displeasure of his 'master' and amusement of bystanders, be- haves as if he doesn't hear a thing. "Fido here, HEEEERE... Bad dog, come here immediately!" None of it helps, Fido pretends to be deaf. Of course he hears his master call and plead, he just doesn't listen. During those moments some dog owners doubt the good ears of their unfaith- ful companion and try with abnormally raised voice to get the message across, with little result. It all has to do with the fact that the owner often does not understand that the dog does not comprehend spoken words. A dog, any dog, does not understand spoken language, any lan- guage. Words and their underlying meaning are wasted on the dog. Fie is better at dealing with clearly separate sounds and particularly when they are heard in the same (preferably happy) circumstances. Whistle to the dog and immediately give him a dog treat. After a few goes (depending on breed and individual) he will walk towards you when he hears you whistling. After a while you omit the treat, of course, other- wise Fido won't be able to walk because of obesity. It is important that we always sound the same whistle. If we suddenly let Beethoven's ninth symphony pass our lips then there is a good chance that Fido will look at us with incomprehension. With the dog whistle described here we can consistently generate the same sound. In addition, the circuit produces an ultrasonic tone which is not audible to humans but which a dog can hear. In this way 'calling' Fido is not noticed by others. The circuit also makes a suf ficient racket to be able to call the dog back from a large distance. The electronic dog whistle shown in the schematic consists of a piezo- tweeter (LSI, a high frequency speaker that can reproduce frequencies higher than 20 kHz), which is driven by a so-called bridge circuit. The bridge circuit actually consists of two switching stages, namely T1 and T2 on one side, and T3 and T4 on the other side. The switching behaviour is each other's mirror image (inverted with respect to each other). When the output signal on the left half is high (T1 conducts and T2 blocks) then the right half is low (T3 blocks and T4 conducts) and the other way around. When the bridge circuit is driven with a square wave, the full power supply voltage as applied across the tweeter, which alternates at the frequency of the square wave. The output vol- ume is doubled because of this reversal. That is because the membrane in the buzzer moves both inwards and outwards from it rest position. Without this trick the membrane would move in only one direction (depending on the polarity), either inwards or outwards. The bridge circuit is driven by the square wave oscillator built around gates IC1.A to IC1.C. The frequency of this square wave is above the human threshold of hearing and is determined by the RC-network PI/ R1/C2. The left switching stage (T1/T2) is driven directly by this oscil- lator and the other stage via the, as buffer and inverter functioning, parallel connected gates IC1.D to IC1.F. f To prevent Fido from being punished unjustly because he does not react to the dog whistle any more while the blame should be placed on the empty battery, we have added a battery indicator in the form of an LED (D1). This LED is lights up only when you press button SI and the tweeter is driven. This optical indicator is necessary because we can- not, after all, hear the dog whistle. If the LED stays off then we have to replace the battery (and not the dog). I Build the circuit on a piece of prototyping board. For the power supply use a 9-V (rechargeable) battery. Suitable tweeters are, for example, types KSN lOOIAorKSN 1005A. You need to test the circuit before you can use it. Turn potentiometer PI so that you can hear the whistle (if need be, increase the value of C2). You now know that the circuit generates sound. Obviously LED D1 should light up as well. Now turn PI so that the sound becomes inau- dible. If you are still young and don't have disco-ears, you may assume that other people won't be able to hear it either. If you've spent too much time in the disco or are not that young any more then ask the help of a young child, because a younger person can still hear high fre- quencies! Adjust PI in such a way so that a young person cannot hear the whistle more. The dog still has to look up surprised when you press push button SI. This is a sign that everything works properly. Once the circuit is calibrated, the 'calibration' of Fido can commence. Don't hold the dog whistle too close, because the thing produces a lot of noise to his ears. He could run away never to return, and that was not why you built this! Start the training in you back garden (or at one of the neighbour's if you don't have one yourself); at least Fido can't escape this way. When the dog is far enough away, activate only the dog whistle and not your voice. If the dog shows an inclination to come towards you then squat down and encourage him by talking to him with a happy and high pitch voice. Reward him with a dog treat when he walks towards you (never walk to the dog!). Condition this behav- iour by doing it often enough (obviously with rest breaks in between) before taking Fido into the street. i-TRIXX collection 17 etector ]>o you know the saying l Though the lie be swifti the truth overtakes it 1 ? If youi based on the wis- dom of practical experience! doubt the truth of this sayingi then you place perhaps more faith in a lie detector- American judges do thisi they accept the result of a lie detector test as supporting evidence- Fertunately there is a big stretch of water between the US and V P2 R1 rvi pGO 2x 1N4148 R4 R5 |_10k If you would like to play CIA- or FBI- agent and subject people to a test of trustworthiness, using electro- nics, then you can build yourself a lie detector. An advance warning: doubt the indication of this device before you doubt the honesty of the person concerned, or you will be left with very few friends! presented here measures just the latter reac- tion: a change in sweat production, that is, a change in skin resistance. 47k LF356 ± 100m A lOOn 10k A lie detector does not give reliable results. That is the reason that European judges do not accept the device as evidence in a trial. Nonetheless it is interesting to experiment with one of these and hence the reason we present a simple, make- your-own, lie detector here. The electronic detection of a lie is based on the fact that various physiological reactions can be measured when a person lies. So there are changes (or said in a better way: there may be changes) in blood pressure, breathing, heartbeat, skin temperature and the amount of perspiration when a person adamantly lies The circuit The measurement of the skin resistance is done with the aid of two electrodes that are stuck a certain distance apart on the skin of the 'suspect'. The sensors can be made from, for example, small pieces of circuit board. Solder flexible wires to the copper side of the small plates and connect them to the lie detector. You stick the small plates with the conducting surfaces with bits of tape to, for example, the underarm. The skin has a certain electrical resistance between the sensors. If the 'suspect' feels uncomfortable with the questions asked then he will literally break into a sweat with a resulting change of skin resistance. This change is sensed by the lie detector and has to ring alarm bells with you, the questioner. To have any hope of 'reliable' results you have to ask simple questions and not something along the lines of: Is this the first time you have lied today?... The schematic shows the electronic contents of the build-your-own lie detector. Since we want to measure small changes in skin resistance and not the absolute resistance value, it is not sufficient to make a simple ohmmeter. The circuit filters only the change in skin resistance in gives a clear indication on the moving coil meter. The meter (Ml) that is used here has a null position in the centre of the scale and can therefore indicate both an increase and a decrease of skin resistance (the scale itself is not important, only the movement of the pointer is relevant). Since the skin has a resistance ranging from a few thousand ohms to several tens of kilo-ohms, the circuit is provided with a high-impedance input amplifier in the shape of opamp IC1. This opamp drives with its relatively low-impedance output both meter Ml as well as a second opamp (IC2). This second opamp has deliberately been made to react slowly with capacitor C2. Slow changes in skin resistance and therefore also slow changes in output voltage of opamp Cl are fed back through IC2 via R1 and P2 to IC1 with the result that the output voltage of IC1, and therefore also the meter deflection, hardly changes. On the other hand, a fast change of skin resistance and therefore also the output voltage of IC1 is not compensated by IC2 (C2 effectively shorts-out fast voltage changes), so that the meter (Ml) deflection indicates that the 'suspect' is feeling extremely uncomfortable. 18 i-TRIXX collection A remark about the meter. As already mentioned it has to be a (panel)meter with a null position in the middle; it has to be able to show a change in skin resistance, after all. The sensitivity of the meter is not very important. If you happen to have another type with a different sensitivity than the 100 jiA indicated then you just change the value of resistor R3 accordingly. Don't use an electrolytic capacitor for C2. This type of capacitor has too high a leakage current for this type of application, which upsets the control system of this circuit. If you are unable to obtain a 1-pf version then you could also use two 470 nF capacitors in parallel. Instead of the in the schematic indicated types for IC1 and IC2 you can also use any of the following: LF355, TL061, TL071 or TL081. In the interest of safety, the circuit may only be powered with two batteries of 9-volts each (so do not use a mains adapter!). Just to be extra safe, do not stick the sensors so that the heart region is between them. Also do need stick any sensors on the head. Although the current that flows through the skin is very small it is still better to avoid taking any risks. It is best to attach both sensors, for example, to one arm or one leg. After the sensors are attached you have to first calibrate the circuit. Slowly (!) turn potentiometer P2 until the meter is in the centre position and indicates zero volts. It can take a while before the measured voltage settles down. The lie detector is calibrated once this is the case. Push a little on a sensor. If the circuit is functioning properly then this will cause the meter needle of meter Ml to move a little. You can adjust the sensitivity of the lie detector to your liking with potentiometer PI. You will, of course, set the sensitivity very low when you are yourself subjected to the lie detector by a friend! Artful LEO dimmer Turning an LED only on and off? That^s a very meagre use of ail the possibilities that mo- dern high-ef H ciency pe- wer-LE])s of 1 to 3 watts have to offer- With a Low-Loss dimmer you can have a nice continuous control of the Light output- Take three power-LEDs of dif- ferent coLour-i build three simple LED-dimmers and you can create a ma- gical play of colours- While such a device is available ready-madei you can build one yourself for much Less money with the benefit that you can make it just the way you want- -S, For certain applications it would be nice if the brightness of LEDs could be adjusted in a continuous manner. This is particularly true when, for example, you want to mix the colours from three different coloured LEDs. That can be done with the circuit described here, which you build three times for this application. If you use a slide potentiometer for PI and position all of them next to each other then you can adjust the brightness by moving them together and change the colour mix by moving them individually. The circuit (which you have to build three times for the suggested application) is built around the familiar timer 1C NE555. Normally, the discharge connection, pin 7, is used, but in this application the time determining capacitor C2 is charged and discharged from the output (pin 3) via R1, PI and both diodes (D1 and D2). The diodes make it possible to change the pulse/space ratio of the square wave at the output over a wide range from 0.5% to 99.5%. The frequency of the square wave remains quite constant throughout at around 1 kHz. Because of the persistence of vision of our eyes we cannot sense this fast on and off switching of the LEDs and we see a nicely averaged light output. A MOSFET (T1) is connected to the output of the 1C. When this FET is turned on it behaves as a very low resistance and can therefore switch a relatively high current without becoming too warm. It can drive a power LED (D3) with a maximum current of 1 amp without a problem. i-TRIXX collection 19 Failure detector for freezers Electrical appliances are expected to worki that is what theyVe made for after all! Technology will however let you down from time to time- Just one occurrence of water leaking from the freezer it is a small domestic disaster- An electronic failure detector could have warned you in time so that you could quickly move the perishable contents to a neighbours freezer- Vou must of course not wait to build one of these detectors until the problem presents itself- UJe have to build it now! The circuit described here is not only suitable for refrigerators and freezers, but can also be used to guard other, periodically or continually operating appliances operating from the mains, such as fresh air ventilators, pond pumps, etc. The circuit checks, based on the current drawn by the appliance, whether it is still doing its job or not. If no AC current is detected within an adjustable time period then an acoustic alarm reports that something is wrong. To detect whether or not current is drawn from the mains by, for example, a freezer, we use the fact that there is a magnetic field around every current carrying wire. In the case of the AC mains this is an AC magnetic field. We pick this field up with a coil of a surplus low voltage relay (we used a 24-volt Siemens relay, type V23027-A0006-A101), which we take apart until we're left with only the coil with internal iron core. By winding one of the current carrying wires (either phase or neutral) from the freezer around the core, a voltage is generated in the winding as a result of the electromagnetic field. Without making a dangerous, electrically conducting connection to the mains, we now have obtained a (magnetic) coupling between the freezer and our detector! But it can, and has to be, much safer still, because to be able to wind a conductor around our DIY current sensor we would need to strip the outer insulation from a short section of the freezer power cord. We obviously would leave the insulation of the individual wires (and that are 3 of them, including protective earth, PE) intact. A power cord with its outer sleeving partially removed could not be called safe any more, of course (the insulation is no longer what it was before). u B 5...15V BAT41 Cl □ ©- 10n 25V D1 PI JBT 100k D2 BAT41 R1 H 470 Q | * i D3 8 © R THR IC1 DIS OUT 7555 TR J. CV LJi C2 lOn 7555 I ‘ l X I A* R3 * IRFD024 5 C3 lOn IRFD024 070056-11 Because of its better accuracy and lower power consumption the CMOS type 7555 (or LMC555) is preferred for IC1. Also better are the Schottky diodes indicated in the schematic for diodes D1 and D2. They are only slightly more expensive than ordinary 1 N4148, which could also be used. A suitable power supply is a mains power adapter with regulated output. If the adapter is rated at 1 A, then you can power 3 dimmers with 1-W LEDs, or one dimmer with a 3-W LED. For three dimmers with 3-watt LEDs the mains adapter needs to be rated at least 2.1 A. Remember that the power LEDs need to be cooled. You can, for example, mount them on a length of aluminium angle profile (see photo). With the value for R3 shown in the schematic and a power supply voltage of 5 volts, any arbitrary red, yellow or green LED (not power types) with a diameter of 3 or 5 mm (50-milliwatt types) can be connected. The dimmer circuit can be built quite cheaply. The most expensive items are probably the slide potentiometers. You could also use cheap trimpots and adjust the brightness and colour mix of the LEDs in a more permanent way. The circuit is really a little bit excessive when adjusting the brightness of a single small LED. It is different though when you want to connect multiple power-LEDs in series or create an artful effect with the mixing of colours, as you can see in the photo. This circuit is then much cheaper compared to devices available ready-made. The accompanying table is a handy aid when determining the power supply voltage and the value of resistor R3, depending on the number of LED's (=D3) connected in series. type red, yellow, green 3 + 5 mm blue, white 3 + 5 mm Power LED 1 W Power LED 3 W UF 1.9 V 3.7 V 3.4 V 3.5 V U B 1 25 mA 25 mA 300 mA 700 mA 5 V LED’s 2 in series 1 1 1 R3 47 0- 1 / A W 56 O - V. W 5.6 O - 1 W 2.2 O - 4 W 7.5 V LED’s 3 in series 1 2 in series 2 in series R3 82 O - V, W 150 O - 1 / A W 2.2 O - 1 W 0.68 O - 1 W 9 V LED’s 4 in series 2 in series 2 in series 2 in series R3 56 O - 1 / A W 68 O - 1 / A W 8.2 O - 4 W 2.7 O - 4 W 12 V LED’s 5 in series 3 in series 3 in series 3 in series R3 100 0-V.W 36 O - l / A W 6.2 O - 1 W 2.2 O - 4 W 15 V LED’s 7 in series 3 in series 4 in series 4 in series R3 68 O - 1 / A W 150Q-V.W 4.7 O - 1 W 1.5 O - 4 W 20 i-TRIXX collection L . !• - a We solve this problem by using a type of enclosure which is readily available and has a built-in plug and socket (see photo). We can take the plug of the freezer power cord and plug it into the enclosure and then plug the enclosure into the power point. The enclosure therefore ends up between the mains and the freezer. Each of the three mains connections (phase, neutral and earth) of the plug is connected to the appropriate connection in the socket of the enclosure using appliance wire (2.5 mm2). One of the current carrying wires (not the earth!) is wound once or twice around the relay coil. Be careful that you do not damage the fragile coil winding (perhaps wind some insulation tape around the coil first). The actual current sensor is now finished. The only thing that is now missing, is the circuit that picks up the signal from the sensor and compare the presence of this with a predetermined time. If no current is detected within this time then we have an abnormal situation and the alarm sounds. You can find the circuit in the accompanying schematic. For safety reasons we fit the entire circuit in the enclosure as well! RE1 represents the DIY current sensor. The remainder of the circuit is nothing more than an adjustable amplifier stage (around IC1A) and a voltage comparator (around IC1 B). We used only one 1C, a TLC272 which contains two opamps (more about that later). To drive the buzzer, a transistor (T1) is also added as a buffer. To increase the signal level from the coil to a usable level, we chose a maximum gain of about 100. In our case the coil gave a peak voltage of about 17 mV when used with a 100-watt lamp. So this results in a peak voltage after amplification of 1.7 V. This voltage is rectified by diode D1 and filtered by capacitor C5 to a smooth DC voltage. Once the previously detected current disappears and because of the large value of C5 it will take about 30 minutes to one hour before the output of comparator IC1 B changes state and raises the alarm with the buzzer. We assume here that a normally operating freezer will turn back on within this time. The guard time depends in the magnitude of the detected mains current, the coil used and the gain set with PI. If need be, the time can be made shorter by lowering the gain. A longer time is obtained by increasing the gain. If that is not enough, then the capacitance of capacitor C5 can be increased. (Use a high quality capacitor for C5.) A longer time is required to ride through the long period of a well-insulated fridge or freezer when the compressor is off. The trick is of course the get the circuit to check only whether the compressor of the freezer still runs on a regular basis and doesn't 'look' at any ancillary things such as indicator lamps, interior light and such. To make the circuit less sensitive to small currents it is possible to increase the value of R6 a little, but this has the consequence that the time duration is reduced somewhat. For the buzzer we again selected a radial, 12-V type for PCB mounting, which still works well at a lower voltage. A pleasant side-effect is that the buzzer also draws less current at the selected power supply voltage of 9 volt. When the buzzer is active, the circuit draws about 12 to 13 mA at 9 V. When the buzzer is off, which in the ideal case will be always, then the current consumption is mostly determined by the power supply current through the opamp. We originally chose a TLC272 because it has a reasonably low current consumption. There are however also two special versions of this 1C: an In- version and an L-version. If we use a TLC272 then the current consumption is 0.8 mA. With a TLC27M2 the current consumption is 0.17 mA and with a TLC27L2 the current consumption of the circuit is only 0.06 mA. When using the latter, a normal 9-V alkaline battery rated at 300 mAh will last 200 days. Using a 9-V mains adapter is also possible, in principle, but we advise against that, because when the mains fails you will be waiting in vain for an alarm! Kit Jf 1 i-TRIXX collection 21 A home-made battery Vou sometimes see them on websites or in the windows of shops selling gadgets: apples or lemons that serve as a battery power supply for small electrically driven mechanisms- Sut it can also be done without fruit- Ue here follow in the footsteps of Alessandro Volta (1745-1AE7) and build our own batteryi which can also be used to clean copper or silver objects- Electric voltage, including that from a battery, is ex- pressed in volts and, indeed, this measure is derived from the name of Alessandro Volta, an Italian physi- cist who lived from 1745 to 1827. Volta continued to research galvanic electricity made by his compatriot and colleague Luigi Galvani (who was a medical doctor as well) in 1780 and built the first battery in 1800: the Voltaic pile. The pile originally consisted of 30, and later of 70, silver and zinc plates separated with cloth soaked in a salt solution. Volta himself called the con- struction an 'electromotor'. We build a variant based on the battery principle: we replace soaked cloth with a glass of water in which salt and sodium carbonate are dissolved and substitute aluminium and copper for the silver and zinc plates. The advantage of the glass of water is that we can put in small copper or silver objects (jewellery) which are miraculously cleaned, but more about that later. Since one glass results in a voltage of only 1.15 volts, we im- mediately start with two glasses, so that with 2.3 volts we can demonstrate the operation of the home-made battery straight away with an illuminated LED. Here is the recipe for the liquid in each glass: 1 teaspoon of table salt (available from the supermarket); 1 teaspoon of sodium carbonate (available from the same supermarket or from the chemist); as much water as fits in a glass of about 200 ml (available from the tap). Stir the solution thoroughly so that the salt and sodium carbonate are completely dissolved. In this solution we now hang a strip of aluminium foil with a width of about 4 cm and about 15 cm long. The easiest way is to fold the end around the top of the glass and hold it in place with a rubber band. Now we strip a piece of flexible copper wire (mains flex) of the same length and hang it in the solution in the same way. Make sure that the copper and alumi- nium do not touch each other, otherwise our battery becomes short-circuited. If necessary, use a paper clip As already mentioned, we make a second battery in the same way and connect it in series with the first: the copper wire of one glass is connected with the alumi- nium foil of the other glass (making this connection using copper wire does not matter). Soldering the wire to the aluminium will not work; clamp the stripped end of the connecting wire under the rubber band against the aluminium foil. We now have two free battery terminals: an aluminium terminal (the negative of the two-cell battery) and the copper terminal (the posi- tive). Between these two terminals there is an open- circuit voltage of 2.3 volts, which we use to power a red (high-efficiency) LED. Connect, with a short length of wire, the short terminal of the LED (= cathode) to the aluminium negative terminal (clamp under the rub- ber band) and the long terminal (= anode) to the cop- per positive terminal. (When connecting the LED there is an easy to remember rule: the short or cut terminal is the cathode.) If you inadvertently connect the LED the wrong way around there is no danger of damage — the voltage is too low for that. After the LED has been on for a while and therefore the battery has been used for some time, you will notice that the copper is nice and clean. This home-made bat- tery is therefore eminently suitable for the cleaning of copper or silver. We omit the LED as well as the copper positive ter- minal. Now we will not load the battery (one glass is enough) externally, but internally! The inside of the glass is now completely covered with aluminium foil and the copper or silver objects to be cleaned (which now function as internal negative terminals) are placed in the solution in such a way that they just touch the foil on the side (an internal short-circuit therefore). After a while they are as new! This is because an extre- mely thin layer is etched away from the outer surface. So don't forget to remove your clean silver jewellery, because after a while you may get the impression that a theft has occurred, without any traces of burglary... The battery is now finished. Between the strip of alu- minium and the piece of copper wire there is now an open-circuit voltage of about 1.15 volts, the copper is the positive terminal and the aluminium is the negative terminal. 22 i-TRIXX collection 4 ■ CL.k’U Wtm A sensitive torch? Vesi one that turns on as soon as you pick it up- This is particularly useful when you suddenly And yourself in the dark and you quickly need a li ght- Nervously fumbling for the en|off switch on the torch and then operating iti is time wasted- And forgetting to turn it off is not a problem any more either because the lamp turns off when you put it downi that saves batteries- Can you buy such a torch? Perhapsi but you can make practically any torch touch sensitive- Sensitive Some torches are usually switched on by turning part (the front or the back) of the housing. There are also types that are fitted with a slide switch. And then there are implementations with a push button. In short, it is a bit of a fumble in the dark when you haven't used the thing for quite a while. What can be easier than a torch which turns on as soon as you pick it up? If you know how to use a soldering iron and can tell the difference between a resistor and a transistor, then add some electronics to the innards of your torch and your torch is now also touch sensitive! m Fortunately, this does not require many electronic com- ponents. And that is a good thing, because finding sufficient spare space in a torch is hard enough. The accompanying schematic contains only three transis- tors and four resistors. With a bit of skill these can be mounted on a small piece of prototyping board and fitted onto the torch. There is possibly enough space .behind the lamp. There may be enough space for a round circuit board (with a hole in the middle) behind the round lamp holder of a cylindrical torch. The operating principle of the circuit is a touch switch, where the skin of your hand is used as an electrical resistance. We glue - in the case of a cylindrical torch - in the lengthwise direction, one or two long pieces of circuit board with the insulated side facing the outside of the metal(!) torch. Check that the outside of the torch is electrically conductive and not covered with an insulating lacquer (a chromed version or an aluminium one would be ideal, for example). The outward facing, electrically conducting copper surfaces of these small strips of circuit board form one side of the touch switch. Both of the copper surfaces are connected with a short wire to the circuit (point B in the schematic). The other side of the touch switch is formed by the metal housing of the torch itself, which is connected to point A of the circuit. Position the strips opposite each other; in this way at least one, together with the housing, will be touched when you pick the torch up! rch When you pick the torch up, the skin of your hand will create an electrically (albeit weak) conduct- ing connection between the copper surface of one or both strips and the metal housing. In the schematic (where we assumed two strips B/B) we can imagine this as a resistor between the connection A and B/B. This resistor activates the circuit. From the batteries on the torch, to which the circuit is connected, there now flows a very small (harmless) current through the base- emitter junction of transistor T1 via resistor R2 and the skin of your hand. This transistor will amplify and pass this current on to transistor T2, which amplifies the current some more and drives transistor T3 hard into conduction. The lamp (LAI) in the torch will now turn on. The lamp turns off when we put the torch down. The circuit draws a negligible small (leakage) current; a separate on/off switch is not necessary. The original on/off switch (SI ) is still available if we want to turn the torch on without having to hold it. This can come in useful in situations where you need both hands and a light. The circuit is suitable for torches with a total battery voltage between 3 and 15 volts and a maximum lamp current of 2 amps. A note regarding the mounting of the circuit in the housing: ensure that the metal cooling tab of T3 does not come into contact with electrically conducting parts of the torch. If your version of the torch switches the positive terminal (the polarity of the batteries is then opposite from that shown in the schematic), it is still possible to build the circuit, but substitute for T 1 a BC547B, for T2 a BC557B and for T3 a BD132. Finally! Here is no-nonsense home automation which is easy to install and to maintain both for the qualified technician as for the DIY enthusiast. The system does not contain any (costly) central unit, which makes it extremely user-friendly, reliable and inexpensive. The VELBUS can be set up and controlled using the classic learning method as well as with a few clicks of the mouse through your computer. The necessary software is available for 1 -CHANNEL VMB1 RY 89€ RELAY MODULE Assembled and tested modules 4-CHANNEL RELAY MODULE VMB4RY 149€ #*■**[ DIMMER MODULE VMB1DM 95€ BLIND CONTROL MODULE VMB1BL 79€ VELBUS PC INTERFACE TOOL VMB1 USB: USB VERSION / VMB1RS: RS232 VERSION 65€ 45€ PUSH BUTTON AND TIMER CONTROL PANEL WITH IR RECEIVER VMB4PD 99€ + FRAME VMBFLG 12 € IR REMOTE CONTROL STICK VMBIRTS 49, 5€ 8 PUSH BUTT VMB8PB 39,95€ ON INTERFACE To connect up to 8 any brand push-buttons More modules on www.velbus.be Price is indicative only // VAT included For dealers see: www.velleman.be Home Automation System plug & play instruments why is Everyone talking about cleverscope?* U nii Vex Robotics Kits Meccano™ Compatible • Computer Control Radio Control Tank Treads Hydraulics FUN FOR THE WHOLE FAMILY! “Imagination is more important than knowledge” Albert Einstein ^ ROBOTS M cleverscope CS3E8A visit our website and discover for yourself www.cleverscope.com J * flupfe-lfflfib weS mry /smm r sff tftsfsnsfogtw Jnd j/fWs 14 Internet Technical Bookshop, 1-3 Fairlands House, North Street, Carshalton, Surrey SM5 2HW www.robotiq.co.uk sales@robotiq.co.uk 0208 669 0769 Awfclrtfc L.rt M l.l T MS-, 'i'li XGAME STATION LcA.qN STTir^Sv-STcr* JlMth OFiljjiw TPUH OWN Mr. cr H-uhv na iJ u -i.r> worn piMf p^Nioyrr &» tn in*fHPWl tr> the WPH WQ/2 WQ. SlftelAl^ Z* Sjweirvm. Jkppfe tl A CanvmKkvff Gfl! twrr # JOFS' ^■..OvmWAUlMWti • AfM Irv Jintfnitt AHD Mudwittf - TTW PNN WiVtltHTTi EN-HIOMij S^IUM ■ l ul'e AmtiUmI RGd- Bilan Ci*Um LW1! ^ SalluMw C i illfl frBiM iM ■ Fflnefc inWp*Ji{ HS# It? iptlrt if WWW.XGAMESTAT 1 QN.CQM SffHEE Rmi 525. VUCi-sas-a I .i DCFin . If still Pulse then logic 1 . / 200 ms = "1", 100 ms =. Decision N. r Yes / Calculation Signbit Signbit = 1 Output Sync LED on 1 -> A2 Connection Point Pulse has ended. Calculation second = sec... / C END y Calcula tion Signbit Signbit = 0 Output Sync LED off 0 -> A2 ’Wait for pulse end. Jump to Connection Point 76 elektor - 12/2007 nal can be detected by the ports used. On the PIC16F88 device, the RA port lines can also be used as analogue in- puts using an internal analogue/ digit - al converter. Assuming a swing of 5 V the resolution is 5/1024 (2 10 ) or about 4.9 mV. Flowcode has an essential advan- tage in allowing software to be easily ported to another PIC type or anoth- er clock frequency afterwards. Here, a PIC type 16F88 was first used with the Multiprogrammer board running at 19.6608 MHz, but the PIC device and clock frequency can easily be changed to suit your requirements. The low- est crystal frequency tested with this project is 6.144 MHz. How it works To be able to follow the discussion be- low, you should have the Flowcode program found in download # 075094- 11. zip on your screen or on paper. After receiving a no-pulse interval of about 1000 ms (20x50 ms), during the 60 th second of every received DCF minute the LCD will synchronise with the correct time, day, month, year read- out. The value displayed on the right of the display gives the currently received bit value of the DCF information during every second. (- for a 0; ^ for a 1). Every minute, the Flowcode-pro- grammed PIC receives 59 of these bits (the 60 th second is represented by a ‘pause’) representing BCD coded values. In order to keep the Flowcode software simple and easy to debug, and also to keep the main program uncluttered, at least three separate program parts are used. Macro 1, called DCF -Synchronize, takes care of the synchronisation in the 60 th second. A second Macro called Getbit receives a new bit value every second and converts any 100-ms pulse length into a logic 0, and any 200-ms pulse length into a logic 1. Macro 2, shown in Figure 1, also waits until the pulses are ended before the program continues with, for instance increasing the Seconds counter, or adjusting its value when value ‘61’ is reached. And last but not least, the DCF_Array[ ] will also be filled here with the measured bit value of that last second. After exactly 59 received seconds, the time/date is distilled from the discrete bit values in order to put the correct information on the clock readout. It will be obvious that it’s essential for this second macro to function flawless- ly, since even if Synchro starts prop- erly, Getbit still tests for a correct 100- ms or 200-ms pulse every second. Eve- ry wrong bit will automatically mean incorrect displayed data, especially when ‘seconds’ run out of sync. Us- ing the software approach described, only AM disturbance at the 77.5-kHz receiving frequency can cause real problems. A third macro fills the LCD in such a way that all data from the 59-second ‘time telegram’ is displayed correctly. In the Main program, finally, you’ll find the BCD conversion math algorithms that convert every bit value correctly for every item and calculate it to the associated decimal values. In the first Flowcode version I wrote, a parity check was missing — no real disaster because it was immediately obvious when any received data was wrong. Moreover, after synchronizing again to DCF it was usually okay the next minute ( a-la-minute \ ). A simple even-parity bit check is implemented in the latest version of the software. Three time zones I had no trouble making a working Flowcode DCF CET clock. But adding CET-1 and CET+ 1 modes was a whole different matter. This is because the German DCF 77.5 kHz transmission only contains CET (= GMT -I- 1 hour) information while it can be picked up (though not constantly) as far as the Polish-Russian border and the Irish West coast. A discussion of the soft- ware adaptations necessary to al- low for three time zones is found in the supplementary document avail- able free of charge from the Elektor website. The setup for E-blocks When using the E-blocks Multipro- grammer board, A0 will be the DCF signal input port. An A0 port LED will Figure 2. Clock, date and DCF reception readout (on PICee board). come on with active-High DCF signal. Similarly, an A2 port LED will light up when Signbit is logic High. Take care! Neither ports A7 nor A1 seemed to function well as a DCF sync error LED indicator output. Port A4 nevertheless functions splendidly for this function, in real life and in PC sim- ulation mode. The A4 LED automati- cally goes out after about 60 seconds when the DCF time signal is success- fully captured. The readout on the 16x2 LC display looks as follows (Figure 2): ST 23:22:12 Thu ~ 26 Apr 2007 .DCF On the readout, ‘WT’ is shown for winter time; ‘.DCF’ when synchro- nized, ‘ERR’ if there is poor or no DCF reception. The day of the week, Sun, Mon, Tue . . . Sat is in BCD code values 7, 1, 2... 6. In case of parity (receiving-) errors the next lines will be displayed: Hour WRONG or Minute WRONG on line 1; D/M/Y WRONG + ERR on line 2 (or a combination of these). Flowcode did it This project like no other revealed the power of Flowcode Professional — the only problem as I see it could be with Figure 3. To make the Elektor February 2002 PICee Development Board E-blocks compatible, datalines D0-D3 to the LCD have to be broken. This is effectively done by setting the centre and right-hand jumper blocks to the 'up' position. The 'low' position allows you to revert to the original PICee mode. 12/2007 - elektor 77 E-BLOCKS pulses that are too fast to be detected by the input ports of a PIC programmed using Flowcode! Over to the PICee board - hardware matters The later version is an adaptation for the Elektor PICee board. Here, port RA4 will be the DCF input after a small hardware modification of the PICee LCD. Port A5 is now assigned to the DCF Error LED, and port A2 still can be used as the Signbit value indicator. The PICee setup has been successfully tested at a frequency of 6.144 MHz. The PICee board be modified to accept the Flowcode-programmed PIC proces- sor. Why, how? Normally, programmed PICs are not exchangeable between the E-blocks Multiprogrammer and the Elektor PICee dev board, although they’re both quite ordinary PIC pro- grammers! The crux: The PICee board sends out its LCD data 8-bits wide. By contrast, the E-blocks Multiprogram- mer board employs 4-bits wide LCD communications . Now Flowcode 3.0 is unable to address its LCD using Port -A and Port-B bits si- multaneously — it employs Port B ex- clusively. The PICee board uses both port A and port B to address the LCD. The two systems can be ‘married’ by placing three double-pole toggle switches arranged as 6 jumpers above and under the PICee LCD. The draw- ing in Figure 3 illustrates the method. Also disconnect the LCD printed cop- per connections in accordance with the drawing. It may be very handy when all new jumpers are fitted in parallel with the LCD (from East to West) so they will be easily recognised as they differ from the direction of original jumpers (North to South). There’s plenty of space on the PICee board, see Figure 4. Fourteen light- duty wires are installed in such a way that the jumpers for the E -blocks com- patible position all point in the same direction (to the left, assuming the LCD on the PICee board is at the bottom of the card pointing downwards; with the component-side showing). The ‘stand- ard PICee’ position is: to the right. Note that not all pins are wire-connected pins but they’re still needed as jumper holders and serve logistic simplicity. Disconnect the following copper con- nections to the PIC socket of the PICee board: Figure 4. This area between the LCD and the LED array at the edge of the 2002 PICee board is suitable for installing the additional juniper blocks to select between E-blocks and PICee mode. Pins 1 (Pic_RA2) and 2 (Pic_RA3) Pins 8 (Pic_RB2) and 9 (Pic_RB3). The four broken connections are now the P(ole)-contact wires of the first two 2x3 ‘changeover’ jumpers. Flowcode adaptations for PICee In Flowcode, if a PIC program using a clock frequency of 19.66 MHz is con- verted to, for instance, about 4 MHz without changing the Delay blocks, then Flowcode will very likely propose a change. Without this change in the timing of the Delay blocks, the DCF clock won’t work as expected! The DCF Flowcode clock works perfectly with any clock between 19.6608 MHz and 6.144 MHz, but not without chang- es at around 4 MHz. The Flowcode software adjustments re- late to the LCD configuration window: all Port B settings must be changed as follows Datal Port B must change to bit 4; Data2 Port B must change to bit 5; Data3 Port B must change to bit 6; Data4 Port B must change to bit 7; RS Port B must change to bit 3; Enable Port B must change to bit 2. These changes do not affect Flowcode in any way because we just use as many Port bit connections as we did before. These small changes have an important advantage in that we do not have to rearrange all LCD data lines on the PICee board to adapt to Flowcode and the E-Blocks Multi-programmer settings. Using the jumper blocks you can switch back and forth between ‘E- Blocks’ and ‘PICee’ mode — with the power supply switched off, right? Conclusion and freebies! Thanks are due to Matrix Multimedia for their fabulous Flowcode Profes- sional version 3.0 software. It is one of the fastest, reliable, and not to forget highly user-friendly (PIC) microproc- essor simulators that helps any enthu- siast to create and realise things that he/she never imagined possible (and all in a very short time)! The Flowcode program for the clock project may be downloaded as file # 075094-11. zip from the Elektor web- site. A free, supplementary archive file # 075094-21.zip contains a Word docu- ment in which the author presents the software revision history, the way he implemented three time zones and the design of a DCF Generator, not forget- ting photographs and screendumps. Well worth having a look at. ( 075094 - 1 ) Reference [1] PICee Development System, Elektor Electronics February 2002. 78 elektor - 12/2007 SERVICING YOUR COMPLETE PROTOTYPE NEEDS 1 EUROCARD (160 x 100 mm) + Tooling + Photoplots + VAT €49 Price example Any size and contour possible! Optional: • Soldermask • Fast-turnaround • Silkscreen • 4-Layer Multilayer • 6-Layer Multilayer oowkmp tm mi umrsmwmr Freephone Q 0800-3898560 »-«** ■* £ \]\\\ ortm Simply send your files A/* A A /I /I # /•/! 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Just try a demonstration copy of Easy-PC and prepare to be amazed... » Easy^PC delivers a simpfe to understand, fully integrated Schematics & PCB layout in a single application. Design and rules checks at all stage* ensure integrity at all times. Professional manufacturing outputs allow you to finish the design process with ease.. Stop press..,. Scop press... Scop press... Easy-PC is supported running under Windows Vista Call for a brochure, prices & CD on +44 tK A {CL +805 1S*£ 450 / 4iOm LM33& 2ZS fft/H J Zel t P/d d£ FS7£g At/s Walter Trojan Natural disasters and freak weather conditions that cause electrical power dropouts, even if only for a few hours, are being reported in the news increasingly often in our part of the world. Wouldn't it be a nice if under these conditions your central heating system kept on working, you could still use the radio or your computer to obtain information or continue working, and the contents of your freezer would stay frozen? In this project, the author has used readily available components and a bit of original design to create a backup power system with an output capac- ity of 300 to 600 VA. Thanks to its port- ability, you can also use it outdoors to provide mood lighting for a barbecue party or power a sound system for sev- eral hours. And in a hard winter, the battery can also come in handy as a booster for starting your car. An alternative to this system would be a high-capacity, petrol- or diesel- powered generator set. However, with such systems you have to keep a store of hazardous fuel, and they produce a considerable amount of noise and nox- ious exhaust gasses. Condition trainer The energy source of the backup power system is a conventional car battery. Here it can be advantageous to use the same type as is used in your car. The author used a 12-V lead-acid battery with a capacity of 74 Ah, which cost a bit more than £ 70 (about € 100). The output voltage at AC mains poten- tial is provided by a voltage converter (12 VDC to 220 VAC) with the desired output capacity (300 to 600 VA). Depending on the loads to be con- nected to the system, you can use a converter with a trapezoidal output waveform or one with sinusoidal out- put. Trapezoidal-output converters with a capacity 300 VA are available from mail-order electronics suppliers for around £ 35 (about € 50). Sinusoi- dal-output converters are twice as expensive. Just add an AC adapter to charge the battery, and you’re all set - or so you might think. Unfortunately, this is not the case. Although lead-acid batteries appear robust, they are actually quite delicate. Despite this, you want to have a power source that is always ready to deliver its full capacity if necessary. To ensure this, the author has devel- oped a ‘condition trainer’ for the bat- tery that provides the following functions: • Charging the battery and maintain- ing it at full charge using an IU Q U p charging curve (see Figure 1) • Constantly activating the battery to maintain its capacity • Displaying battery data and health status All this is controlled by a PIC micro- controller, which in combination with a boost converter also generates the current for charging the battery and maintaining its charge (see Figure 2). The structure of the firmware is shown in Figure 3. Good care prolongs life Lead-acid batteries are rather delicate, so you have to take good care of them if you want them to live to a ripe old age. The conventional car battery used for this project has a rated capacity of 74 Ah, which means it can supply a current of 7.4 A for 10 hours. Car bat- 84 elektor - 12/2007 teries can supply considerably higher currents for short periods, but this conies at the price of reduced capac- ity. If you want to draw 300 VA from the system, the battery has to supply nearly 30 A to the voltage converter if the conversion efficiency is 90%. How- ever, this should be enough for a good two hours of emergency power. For maximum battery life, no more than 70% of the rated capacity should be drawn from the battery (discharge volt- age approximately 11.3 V). The battery should never be deep-discharged to a voltage less than 10.5 V, since this will cause a permanent reduction in capac- ity and may even destroy the battery. Lead-acid batteries also require care- ful attention at the other end of the scale (fully charged voltage). Gas gen- eration, which starts at 14.4 V, should be avoided during charging due to the associated explosion hazard. Another hazard is sulphating, which occurs during discharge and involves formation of a layer of smooth lead sul- phate crystals on the rough surface of the lead plates, which reduces the bat- tery capacity. However, these deposits can be blasted loose by brief, intense current pulses (around 100 A). These features of lead-acid batteries are taken into account by the selected charging curve. It is based on the IU Q U p principle, which means that charging starts at a constant current (in this Figure 1. IU 0 U p charge curve. Figure 2. Block diagram of the circuit. Figure 3. The program structure is abundantly clear. 12/2007 - elektor 85 MODDING & TWEAKING +9V 0 D1 1 N4001 Z Z D2 0 R22 C4 C5 [==□ LI ywv\. 100|iH D3 R23 C15 R21 J-l loop Dll IC3 7805 C> * mw C8 470jll +VDD h© 1.5KE 15CA +VDD 0 - lOOn 470 ^ 2 ? u BUZ11 T1 SB560 C6 C7 [==□ D9 I lOOn 470|i C9 1,5KE 18CA R4 4|a7 CIO lOOn R1 H QQ2 | - 2W R2 IRFZ48N 5W 1,5KE 18CA T2 R5 DIO i R6 OUT A V+ OUT B Q ICL7667 Q A ic2 A IN A V- IN B I R12 R14 X +VDD © D5 BAT42 R17 SI H l LM336-Z25 R13 Jr R15 I Cl 4 lOOp R24 IC4 R16 12 13 18 _ 17_ 11 14 R18 15 R19 16 _ R20 T .1 C3 lOOn © RA4/T0 AN3 RA5/AN4 AN1 IC1 AN2 MCLR AN0 PIC16F876A RC1 RB0 RC2 RBI RC7/RX RB2 RC6/TX RB3 RC0 RB4 RC3 RB5 RC4 RB6 RC5 RB7 _i_ OSC1 OSC2 D6 red blue D8 green Cl 22p XI ii 10 R8 C11 lOOp 11 22 23 24 25 26 27 28 19 P I 20MHz |25 4 T ^ C2 22p 0 r\- is Sample price: 32,50 € plus VAT/shipping Schaeffer AG • Hohentwielsteig 6a • D-14163 Berlin • Tel +49 (0)30 8058695-0 Fax +49 (0)30 805 8695-33 • Web info@schaeffer-ag.de • www.schaeffer-ag.de 12/2007 - elektor 89 INFO & MARKET REVIEW A whole penguin on half a credit card i.MX21 ARM9 Linux-board Paul Goossens The development of a Linux based device is not something that suits everyone. You need considerable knowledge about the inner workings of the Linux kernel. The design of the necessary hardware is quite a job as well. For just over 165 dollars you can buy a complete Linux system with an ARM9-controller from Virtual Cogs. We subjected this system to a close examination in our lab. The Canadian company Virtual Cogs can supply a control- ler board, which has the order number VCMX212, and is based on an i.MX21 (Freescale ARM9 controller) with a clock frequency of 266 MHz. The memory on this board consists of 64 MB of SDRAM and 1 6 MB of flash. All of this (and a little more, but more about that later) is the same size as half of a credit card! Full-Linux Most customers will buy this board because of the possibility of running Linux on it. When delivered, the flash memory al- ready contains a bootloader plus a Linux operating system. The source code for this is freely available of course. The microcontroller used here is provided with an MMU (Memory Management Unit), so that a normal Linux version can run on it. This is in contrast to many other controller boards that use uC-Linux. The big advantage of this system is that on the basis of this much more robust applications can be written. In ad- dition, all the customary drivers (modules) can just be used as well. uMON The bootloader that's factory provided is uMON. This boot- loader is responsible for the initialisation of the memory and can optionally start Linux. In addition to using Linux, the designer also has the option of writing firmware that runs without an operating system. uMON has its own file system, is named TFS, that is used to store various programs in flash memory. In a standard Linux system these are the Linux kernel and an image of the Linux file-system. Additionally you can store a start-up script that describes how uMON has to start Linux. This makes booting Linux very easy. It is also possible to use the file system in uMON from your own firmware. An API is available for this purpose which allows files to be created, read, written and deleted in the TFS file-system. With the aid of a terminal program, such as Hyperterminal, you can easily upload and download programs to and from the TFS file system. We refer you to the website of uMON for more details about other features of this bootloader. In the event that the flash memory is accidentally erased, perhaps after a failed experiment, (despite the hardware protection against unwanted erasure then all is not lost. The controller itself also has an internal bootloader that cannot be erased. Using this bootloader the flash memory can be restored again. Hardware The hardware of the VCMX2 1 2 consists of the above men- tioned i.MX21 controller, 64 MB SDRAM and 16 MB of flash memory. In addition there is also a USB to serial converter from Si- labs, the CP2101 . For Vista users it is good to know that Silabs are, at the time of writing this article, still busy with the development of a suitable driver for Windows Vista. The planned release date for this driver is around the end of 2007. Another method of programming the controller is via the JTAG connector. This also offers the possibility of debugging 90 elektor - 12/2007 the controller in real-time, provided that a suitable JTAG in- terface with corresponding software is available. The board can be powered from the USB connection. If more power is required it is possible to switch to an exter- nal power supply. As a bonus the board is also fitted with 3 LEDs, which can be used as status indicators, for example. Most of the important signals are available via two connec- tors to which hardware expansions can be connected. You can make these yourself, but various daughter boards are also available ready-made from the manufacturer. Expansions Virtual Cogs have developed a number of daughter boards for the VCMX2 1 2. These are all supported in Linux, so that using these is not too complicated. One of these expansions is a graphics screen, either with or without a touch panel. This expansion board also comprises an audio codec with built-in microphone. In addition there is a camera module, an Ethernet modu- le and a break-out board. The latter is very useful if you would like to develop hardware yourself for this system. The break-out board conveniently routes all relevant signals to standard through-hole pin headers. This greatly facilitates connecting your own prototype expansion circuits. For a complete list of expansion modules it is best to visit the Virtual Cogs website. New expansion boards for this system appear at a regular basis. Development environment The development of software for this module is possible with both Windows XP and Linux. According to some reports it is also possible to use this development environment with Windows Vista, but we did not try that ourselves. The installation procedure for installing the (open source) development environment can be found on the Virtual Cogs website. This contains, among other things, Cygwin and gcc-arm. If you have the intention of writing Linux programs, then it is necessary to compile gcc yourself. This is very easy with the aid of the supplied script. It can take a consi- derable amount of time however. Flash file system The Linux system uses the comfortable JFFS2 file-system in combination with MTD to store files. This means that it is possible to create and delete files while running Linux. This behaves the same as if th ere was a hard disk installed. This sounds logical, but on many embedded Linux devices at can be quite an exercise to change files, etc. in flash memory. With this Linux it is simple to do file operations via Ftyperter- minal with Y-modem protocol. In the event that the Ethernet expansion board is also fitted, files can also be exchanged via ftp or even NFS. Support The manufacturer maintains a Wiki with all the relevant information concerning the VCMX212 and corresponding expansion boards. The manuals for the various products are also available online. All the required information to get the development started quickly and without problems is available here. Linux versus pC-Linux In embedded system jL/C-Linux is often used in place of 'normal' Linux. ji/C-Linux is derived from Linux and modified so that this kernel can be used with controllers that do not have an MMU. This means that under /dC-Unux all applications share the entire memory space with each other. An error in one application can result in the corruption of memory of another application. This can lead to problems that are very hard to solve. This system offers also no separation of the hardware from the application software. Under ji/C-Linux the hardware can be controlled directly from the application wit- hout the intermediate layer of the operating system. This means another big hole in the security. Finally we have to mention that not all software that has been written for Linux can be used with jL/C-Linux just as it is. Verdict After carrying out a few experiments we are of the opinion that this board is very suitable for use in your own devices. In particular designers with some expe- rience with programming under Linux will certainly appreciate this hardware. The board can also be used by users who are fami- liar with the C programming language. It is, after all, possible to ignore Linux completely (initially) and write pure firmware yourself. Nonetheless, we recom- mend that in this case that you invest some time to explore programming under Linux. This really allows you to use the power of this board to its fullest. The support for this product by the manufacturer can be called very good. Their Wiki site contains all the information to get you started quickly. And you can also count on the forum for support! ( 070243 - 1 ) The i.MX21 board costs US$ 164.95 plus (VAT and shipping) from Sparkfun. Web Links uMON: http://www.microcross.com/html/micromonitor.html Virtual Cogs: http://www.virtualcogs.com i.MX21 controller The i.MX21 controller from Freescale is a powerful ARM9 controller with a maxi- mum clock speed of 266 MHz. This controller has a number of additional features that make it eminently suitable for multimedia applications. The chip has a video-accelerator on that can (de)code MPEG-4 video in real-time at QGA resolution. It also has an LCD interface and a CMOS camera interface. Communications have not been forgotten either. What do you think about no less than 4 UARTS, l2C-interface, IrDA, USB-OTG and 1 -wire? 12/2007 - elektor 91 LED's Dive! * « a i. Underwater torch using Luxeon LEDs Erik Bonjean It can often be fairly dark under water, especially at greater depths. A diving torch is essential if you want to be able to enjoy the marine scenery (or to help with a rescue operation). It's easy to go out and buy a new lamp, but an old one still has its uses too! More so if we add some powerful LEDs. The secrets of the marine world are of- ten hidden in the darkness. A decent diving torch will help reveal them as it brings some light to the darkness. In this article we’ll describe a battery- powered diving torch that uses a sim- ple, easy to build circuit and an exist- ing housing from an old diving torch, an OceanPro made by Scubapro. Some older divers may well have one of these in the loft somewhere. The cir- cuit presented here fits exactly into the housing of this torch. But there’s nothing to stop you from putting this circuit into a V different torch. Operation The light in this circuit is generated by seven 3-watt Luxeon LEDs connect- ed in series. If you feel this doesn’t provide enough light you can always increase the number of LEDs, since the power comes from a constant current source. The pow- er consumption will obviously increase as well, and eventually the boost converter will reach its (voltage) limit. In the circuit described here the out- put voltage is 23 V and the current at this voltage is J630 mA. This results in a power of 2 W per LED, which is more than sufficient and keeps the heat gen- erated in the LEDs down to a reason- able level. This voltage is generated by an LT1070 made by Linear Technology (see Fig- ure 1). This switching regulator is con- figured as a boost converter and pro- vided with current limiting. This current is determined by four re- sistors connected in parallel, R1 to R4. D2, D3 and R5 are used to turn off the LT1070 when the battery voltage drops below about 10 V. D3 pulls V c low when the sup- ply voltage drops below (1.5 V + V z D2 ) and this turns off the IC. There is no hys- i teresis built into this circuit, so the light will start flashing when the battery is nearly empty, providing an early warn- ing. This circuit also pro- tects the battery from be- ing discharged too much. Without this protection circuit the light would turn off suddenly when the input current to the regulator would increase too much due to the de- creasing input voltage. This is rath- er inconvenient when you’re in the darkness, a long way under water. The rest of the cir- cuit functions like any other stand- ard boost con- verter. The inter- nal switch of the LT1070 can han- dle up to 5 A. 92 elektor - 12/2007 The input voltage is boosted by induc- tor LI in conjunction with this switch. The amount of boost is determined by the duty cycle applied to the switch. The appropriate formula is: ^out = / (1-d.c.) where d.c. is the duty cycle. Capacitors Cl and C2 smooth the in- put and output voltages. In this appli- cation the LT1070 doesn’t really need a heatsink, but you can add one to be on the safe side. The supply is provided by 12 NiMh cells connected in series. This provides a voltage of 14.4 V. The batteries are connected to the circuit via Kl. A bat- tery charger may be connected to K3. The efficiency of the converter is be- tween 80 and 85%, depending on the input voltage. Construction The construction of this circuit is very straightforward (Figure 2). The stand- ard components won’t cause any prob- lems with soldering and there is also plenty of room available (see Figure 3). As usual, it is easi- est to start with the smallest components, in this case the diodes and resistors. Consid- ering the size and weight of the inductor, it is best to leave this till last. The series connected LEDs are mounted on an alumin- ium disc, which has rub- ber rings on both sides that provide a seal tween the housing and the polycar- bonate face- plate. The LEDs are mounted behind collima- tor lens- es made by Carc- lo. These bundle the light from the E D s t o - gether, which would otherwise form a beam with too wide an angle. The LEDS are connected to the converter circuit via K2. L SI LI Figure 1. This simple boost converter fits easily inside the diving torch housing. Figure 2. The size of the board gives plenty of room for all components. COMPONENTS LIST Resistors R1 # R2 = 6D8 R3,R4 = 8D2 R5 ~ 1 l ft , . 1 1 - f r - ■ * fs/ ■ * aL 2 . . _/ r — — . *. luijd fflwy ■ Secure a head start in electronics with a subscription! Cheaper than 1 1 issues from the newsstand Subscribers get up to 40% discount on special Elektor products As a welcome gift you get a free 1GB MP3 player worth £ 34.50 No queues, travelling, parking fees or ‘sold out’ Elektor is supplied to your doorstep every month Always up to date - read your copy before everyone else www.elektor.com/subs Tel. +44 (0) 20 8261 4509 Or use the subscription order form near the end of the magazine. INFO & MARKET SNEAK PREVIEW 0O 2 -sensor The air quality in homes and offices is an important factor that's often neglected. As you breathe and exhale, the oxygen contained in air is converted into carbon dioxide (not carbon monoxide, which is highly poisonous). Al- though a too high C02 level in the air is not dangerous, it does cause effects like fatigue and reduced concentration — just watch what happens during long meetings! The Elektor C02 sensor allows carbon dioxide levels to be moni- tored in an easy way. 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Ltd, Showcase www.decibit.com 102 Designer Systems, Showcase www.designersystems.co.uk 102 EasyDAQ, Showcase www.easydag.biz 102 Easysync, Showcase www.easysync.co.uk 102 Elnec, Showcase www.elnec.com 102 Eurocircuits www.eurocircuits.com Ill First Technology Transfer Ltd, Showcase . www.ftt.co.uk 69, 102 FlexiPanel Ltd, Showcase www.flexipanel.com 102 Future Technology Devices, Showcase . . . www.ftdichip.com 102 Futurlec, Showcase www.futurlec.com 102 ILP Electronics Ltd, Showcase www.iipeiectronics.com 102 Jaycar Electronics www.jaycareiectronics.co.uk 2 Labcenter www.labcenter.com 112 London Electronics College, Showcase . . www.lec.org.uk 102 Marchand Electronics Inc, Showcase .... www.marchandelec.com 102 Mikro Elektronika MQP Electronics, Showcase. . . . New Wave Concepts, Showcase Newbury Electronics Number One Systems Nurve Networks Paltronix SK Pang Electronics Peak Electronic Design Pico Quasar Electronics Robot Electronics, Showcase. . . Robotiq, Showcase Scantool Schaeffer AG Showcase Tsien (UK) Ltd, Showcase Ultraleds, Showcase USB Instruments, Showcase . . . Velleman Virtins Technology, Showcase . . www.mikroe.com 14,15 www.mgp.com 103 www.new-wave-concepts.com . 103 www. ne wburyelectronics. co.uk. 79 www.numberone.com 79 www.xgamestation.com 69 www.paltronix.com 39 www.skpang.co.uk 89 www. peakelec. co.uk 69 www.picotech.com 75 www.quasarelectronics.com . . . 99 www.robot-electronics.co.uk. . . 103 www.robotiq.co.uk 103 www.ElmScan5.com/elektor . . . Ill www.schaeffer-ag.de 89 102,103 www. componentbin. com 89, 83 www.ultraleds.co.uk 103 www.usb-instruments.com . . . . 103 www.velleman.be i-TRIXX backcover www.virtins.com 103 Advertising space for the issue of 21 January 2008 may be reserved not later than 21 December 2007 with Huson International Media - Cambridge House - Gogmore Lane - Chertsey, Surrey KT16 9AP - England - Telephone 01932 564 999 - Fax 01 932 564998 - e-mail: aerrvb@husonmedia.com to whom all correspondence, copy instructions and artwork should be addressed. 12/2007 - elektor 111 LE com»uret, a * rv D D^SluN TowCflul, io Use Sc>^£^iic. C^piufe 5 InicfAciivfi fliVe4 flodc S?lC6 SimulAtio* j Utm^uC flier otonif oiler Co-SiMwlAiiow W DeW^m^ FuUvf FeA,iure4 TC4S Desi^vt *W 3D viewer Worlds First $c^e^tc> US& Simvta'fciow Trtxiuct N£l4 0 ' 6«jmeeri«3 Solution — - t^Apidi Development Environment - Maximum Ketvrn on Investment - Foster Time to Market * * . 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