V 1 M* 1 k \f jM XP .r r » 1 / (Tj r| 1 rf J (Ofl'IMH ITjTj Pro/etls & DIY galore ... LET AUTUMN BE WET ESR/C Meter • Barometer/Altimeter • USB-RS232 Interfacing • Racetrack Tinier • U/S Distance Meter . . . hM Want a FREE catalogue? Just fill out the catalogue reguest form at ujumi.jaycarelectronics.co.uh/elektor Check our website! * Browse our website www, jay taretertrontcs.co.uk > All of our 6,0004- products with search facilities, * 128-blt secure on-line ordering - safe & secure. 1 Over 3,500 product datasheets & application notes * And we're from Australia, so you can trust us! ■ Postage and Packing includes airmail to the USA Midi/PC Based Theremin Synthesiser Kit [__2 ) \^\ KC-S410 £52.75 4- post and packing l - Many thousands of people are enjoying playing our traditional Theremin syntb, but this new design blows that out of the water! It actually interfaces with a MIDI accessible synthesiser or a PC with a sound card, This allows it to play up to 120 different instrument selections, in 15 types by S variations. That Ls slot of sounds! These notes are then changed In pitch by moving your L hand between the antenna and plate, just like the traditional there min. See our website for a full list of great features. The kit includes the circuit board, machined and printed front panels, all electronic parts, and clear engllsh instructions, * Wall adaptor required. Use Maplin #MGS0B £5.99 JUST ONE OF OUR MANY GREAT PRE-BUILT & TESTED PRODUCTS’ USB 2.0 Surround Sound Simulator for Headphones XC-48B2 £12,75 -r post and packing This tiny device takes your regular stereo signals and transforms it into simulated stereo surround sound. It makes your games, CDs, and DVDs come to life. It also has a graphic equaliser and room simula- tion, It is powered by the USB port, so no wall adaptors or batteries are ^^0 required. Lead Acid Battery Zapper Kit KC-5414 £11.75 4- post and packing This simple circuit is designed to produce bursts of high-energy pulses to help reverse the effects oF sulphation In wet ' lead acid batteries. This is particularly useful when the battery has been sitting For a period of time without use. It's effects depend on the condition of the battery, but the results can be quite good indeed. Kit includes circuit board, case, leads, electronic components, and clear English instructions.. M m JV LED Clock Watchers LED Clock Kit KC-5404 £41.75 4 post and packing It consists of an AVR driven dock circuit which drives a 12 or 24Hr display. Also, around the perimeter are 3mm LEDs, and 5mm LEDs every 5 seconds. The clock produces a dazzling display as it counts the seconds, which is so good, it can t be properly explained here. For this reason, we have filmed It in action and put it on our website so you can see for yourself. The kit includes the circuit board, electronic components, pre programmed AVR micro, and dear English instructions, * Wall adaptor required. Use Maplin #GU1DL £9.99 Measures 30fW>x SOIL) x 2QCnmm. Get the Video Quality You Paid For With Our Doctor Video Kit KC-539Q £3L95 + post and packing Copy protection is put in place on videos and DVOs for a good reason, but this robs you of the tme high quality reproduction that it is capable of. Get the quality you paid for and strip out these annoying signals! it supports composite and 5-video signals and can be configured for NTSC or PAL format.. Kit includes case, circuit board, all electronic components, and clear English instructions. Note: Some f ^ ! 5MD soldering required. \ ,-7^ ■ Wall adaptor required. Use L.?ji ) r^rfTr Maplin SGU09K £9,99 W Bass Response Extender Kit KC-54T1 £6,00 4- post and packing All speaker systems in a home stereo setup have a reduction in bass volume as the frequency gets lower. This is due to the enclosure used and the way it Interacts with the speakers. This project boosts the level of bass to counteract _ . | the effects of this reduction, to give ^ /,y | ^ you enhanced bass performance. * , . i & Kit includes the circuit boards electronic components, and dear English instructions. ^ ^i We Stock Caution: During signal conditioning,, this unit removes copyright protection. Piracy is a crime, & Jaycar Elettronscs takes no recptmribiJtty for its potential for unlawful Log on to www.jaycareIectronics.co.uk/elektor for your FREE catalogue! 0800 032 7241 [Monday - Friday 09.00 to 17,30 GMT + 10 hours only}. For those that want to write 100 SiJverwater Rd SlEverwater NSW 2128 Sydney AUSTRALIA Electronic Components & Sub-Assemblies Power Products & Accessories Audio & Visual Equipment & Accessories Computer & Telecoms Accessories Surgular Alarms & Surveillance Equipment Lighting Products & Accessories Gadgets & Unique Gifts Post end Packing Charges; Order Value CoSt £20 - £*9S9 £5 £50 - £99 99 £10 £100 - £199.99 £20 £200 - £400.99 £30 £5004- £40 Max weight !2B> 1 5kg) - heavier 1 pamfaPOA. Minimum ojiler -£30. | ns vv V fou* ) MikroElektronika MICROCONTROLLER DEVELOPMENT TOOLS from Bread oardi g Systems Make PICmicro® development easy with the EasyPIC3 - only £99! The new EasyPIC3 Development Board combines a versatile develapment/experiment board with a built-in USB programmer. With its wealth of on-board 10 devices and support for virtually all 8, 14, 18, 28 and 40-pin PICmicro 1 microcontrollers in the 10F, 12F, 16F and 18F families, we’re certain you won’t find a more ver- satile high quality board at such a low price. The EasyPIC3 Development Board is supplied with USB pro- g ramming/power cable, programming software and useful example programs. Also available are similar boards for the 8051, AVR and dsPIC. each at the same great price of £99 including UK delivery and VAT — please telephone or see our website for further details. EasyPIC3 Development Board features: • High quality deveiopment/expenment board with built-in USB 2,0 high-speed programmer. • Programming software compatible with Windows operating systems including 2000 and XP. • Comes with a PEC16F877A microcontroller but compatible with virtually all 8, 14 : 18, 28 and 40- pin PICmicro" devices in the 10F, 12F, 16F and 18F families. • On-board I/O devices including switches, LEDs a seven-segment displays, potentiometers and RS- 232 interface. Nov/ also features USB and PS/2 keyboard interface connectors. • Provision for easy fitting of optional DS18S20 temperature sensor, and LCD and GLCD dis- plays. • All I/O lines available for off-board expansion. • Wide range of optional add-on boards available including ADC T DAC, EEPROM. Compact Flash, MM C/S D, Keypad, RTC, RS-485, CAN and IrDA. Additional add-ons available soon, • Powered from your PC's USB port or optional mains adapter. • Supplied with example programs written in assembly language, BASIC, C and Pascal. • Supplied with Microchip Technology's MPLAB development software and demonstration versions of MikroElektronika' s mikroBASIC. mikroC and mikroPascal compilers. Learn about microcontrollers with our EasyPIC3 Starter Pack - just £149! We've taken the EasyP!C3 Development Board and added a 16x2 character LCD display, 128x64 graphical LCD. DS18S20 temperature sensor, RS-232 serial communications cable and our own easy-to-follow microcontroller tutorial to form a complete and self-contained Starter Pack— everything you need to iearn about and experiment with microcontrollers! With this pack you will quickly become proficient in microcontroller programming and interfacing. Please see our website for full list of covered topics. Make programming easy too with mikroBASIC, mikroC and mikroPascal Three incredibly easy-to-use yet powerful compilers for PICmicro"' microcontrollers, each featuring a user-friendly code editor, built-in tools and routines and source-level debugger. Supplied libraries facilitate rapid development and include ADC, CAN, Compact Flash, EEPROM, Ethernet, Graphic LCD, i s C, LCD, 1-wire, PWM, RS-485, sound, SPi, USART, USB routines and many more. mikroBASIC and mikroPascal— £99 each, mikroC— £149. Cal! 0845 226 9451 or order online at www.breadhoarding.coMk All prices include UK delivery and VAT. Major credit and debit cards accepted. Secure online ordering. ading the w ay A word or two in the Inbox It's great to see that our website at www.eleklor-electronics.co.uk is maturing and drawing more and more visitors every month, if 3 om not mistaken it is the fourth major version of Elektor's Internet presence, the first dating back to about 1 998 when v/e held only a couple of 'who are we' pages on a Free Com- puServe homepage/email account with dial up access. I remember many of my colleagues in the subscription, sales, design, commercial, advertising and edi- torial departments jumping the oand- wagon and cheerfully reading and answering emails from a single (!) email account. In the [not so rare) case af just one person 'new to email' having forgot- ten to tick the 'Leave Mall on Server' Box in his/her email client program, a dozen or so Inboxes, including mine, would fall strangely silent all of a sudden, A lot has changed since those early days. The Forum on our current website has been modified to allow every website visi- tor to view all messages. However, you need to be legged In to answer ana/ or create topics. The aim of the Forum is to establish contact between readers, allow- ing them to solve each other's problems and, tn general, exchange ideas. It is not intended for direct correspondence with our design or subscription staff, or myself although I will do my best to post the odd reply. Separate email addresses are avail- able For all deportments, guaranteeing a much faster response! Also, the 'Service' page of our website — and in particular the FAQs item — contains information requested in about 6 of every ] 0 contact form' emails we get, so please review these pages before emailing us. Our on-line subscription order farm has been updated and is now protected by SSL, as is the checkout from our Shop. As an experiment hopefully leading up to the availability of an online subscription ro Elektor Electronics, the July/ August 2005 Double Summer Issue has been available for downloading as a (huge!) pdf File. It may still be available as you read this, so nave a look under 'Maga- zine'. For reasons explained in a recent E- News item (now in the Mews Archive), having an online Elektor Electronics repre- sents tremendous benefits far our overseas readers suffering from shipping delays, import regulations and outrageous cover price markups at their newsstands. Finally, the number of subscribers to our E-Newsletter is rising steadily, many read- ers having discovered that the Newsletter automatically delivered by email every Friday is a relatively smafl document of less than 50kbytes — nothing towards dogging up your Inbox. In the past, a lot of space in hobby rooms and work stations was taken up by an instrument in a large case with a small screen, but now many of its functions can be performed using a PC. A small box can transform an ordinary PC into an oscilloscope with extensive functions, in many cases including several extra Functions. Elektor Electronics subjected eleven of these 'USB oscilloscopes' to an extensive evaluation. Jan Buifing, Editor know-how The Xbox made by Microsoft is a very popular games console. What many buyers don't know is that the Xbox is really just an ordinary PC running a special (modded?) version of Windows. This leaves the door open to experimenting, for example with Linux. But first you have to get round a couple of modifications, which for many is all part of the fun. So let's get started! The Kvo most important properties of a capacitor ore its capacitance and its internal resistance (ESR). You need to know both values in order to judge whether a capacitor is suitable for a particular application. The meter described here combines Kvo popular Elektor Electronics projects to create o convenient new instru- ments that rightly belongs in every well-equipped electronics lab. I 8 USB Oscilloscopes hands-on Xbox Modding & Surgery 30 ESR/C Meter 44 Hitting the High Note Precision Barometer/Alti meter 62 Racetrack Timer Design Tips Recycle fhose electronics parts! — Ohm's Lav/ wheel — Data doubler for HT1 2E — Low-cost plug-in board — Lav/- cost LCD module technology 38 USB-to-RS232 Hurdle Race 68 Delphi for Electronic Engineers [ 7 ) 74 Solar Lamp info & market 6 Colophon 8 Mailbox Corrections & Updates 1 News & New Products eZ80 Acclaim (review) 82 Elektor SHOP Sneak Preview infotainment 78 Quizz'away ( 1 2) A 3 Servicing Ydur Complete Prototype Needs O Prototypes at a fraction of the cost O Too and setup Included O Any contour 0 Ff4 tBoim, 35ym Cu -iL.'D.yfi BUROCARD z&ptm O Industry siawfc/tf < 71 / 5 % 0 C 4 M / G 3 D -f fcoftflg + T/io/op/ofs + Mr £ 29 . 89 * r^smay retry- Pries = €49 **? IfTE ir lc; Eccc irr fzz+iS3&41Hm* f Jfctf tifrjifflfritrfryTr t~ "•ST**® 6 * o * 00 ' 3 5/mp.y jsa:/ pour fe ffljrfwifef OiYiM: IViyiV.PC8-P0Ol.COM ICWtitt i oread ■. geme ^ SS’ir QG r : GCn? lectronics Volume 3 1 . Number 346. September 2005 ISSN 0268/45 1 9 Oektor Bear owes arms at inspiring people to Piaster electronics at any person- al level by presenting construction projects and spotting developments in elec- tronics and Information technoEogy. Publishers Etefenr E&ctrancs (Ptjfe&h^ngJ, BO, Sox 190. TLriidi^geWfefe TN5 7WC Errand — - - 44) (D) i 500 300657* eejc (a- 44) (Q) l 5BQ 3006 \ 6. vAv« The rregzrne s sys^te btYrt ne^^eris, boGfeii ops sud rieOtftras retni oiMfets. cc on suh- KJ^5t5QO- Ee^cr E^ctrarsij s puftfehed 1 1 tmeS a )rer v.-ih s dQwfcfe dase for July £t Augt^L LJhtkr the rame Eyt&y end Briton the rr^zre 5 aso pu&ldhed n Fhendv Gsmnssv^id Djfcft tether wifi sed zGt ors the rr^szre fe on arojfeScfi n mere tten 50 omuntrieS- International Editor v r at-- _ ei - - - - Editor: ! z r E_z _ £ - ’ --■ ' - - International editorial staff; -e." - - Ee££: _ ~- s = ■::- z's E— r: ■ -t-zz e: :s " , z--: Gc- Z z:z: :: r" Design staff; Davsdi Dsamesi (head of design). Ton Gsesijens, “e _ G: z i :-: is — : _■: m - c - j ■ e j '-: .V= -e, . ■:■ r E d i t o ria E s ecretaiiat: Heriwvg Heniiekens (i ecreteJ^at@^e-E~ e Graphic design DTP; - : - 7_ :e 3: 7 z : Managing Director Publisher: ~e_ 5 'a-- •:'£ Marketing: Ee:- ’ zet-z :o: z • A VI Tke search .co.uk USB to TTL Serial Cable $'”r 5 an Easy ••.■*, :o gr.-g- U33 supf^'t re - ••Jssrin- • Connects directly to mscnjccrEtrofier UART or I/O pins PI .. r IT. J r ;- 3 tE - :■! ^ 55 ' a' CSV ce - • c :t . integrated zt a'eE- rntu d-ed USB z _-j • *i -v, e )• c c r re-:: t>' G rd RX IX a~z - 3 . ■ Si. ppl 5 z .Tin FZ dr .ars e c >za and fctona Speeds 7: zs of c-ny- 29.5 =r nerja ~j VAT AVIT Research also supply: ! 2 C BUS Tool - Allov;s your id mcnitor ana eoniroi the FC Bus' • I a t3 : 'jsc e te fs f de vet zests us'eo the ! 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Gc^r«z±£ i - z it: : _ zz-z - : : : z_z ztlz- zt.t. .t _ : £.. -z: . ; ?- z~ _t= e - . . , ; zz z © Segment b.v. 2005 Printed in the NetheH^ndi 6 clskfcr cicdtomEi ■ 9; 2DQ5 SERIAL COMMUNICATIONS SPECIALISTS Test and Measurement Solutions Jill Duo: E a s y S Y N C , p NETCOM-813 8 Pori RS232/ RS422/RS4 85 mode! £350 NETCOM Ethernet- Serial Servers NetCom are industrial siren glh, network based serial device servers for connecting RS232, RS422 and RS4S5 serial devices directly lo a 10/1 OOMbps Ethernet network running TGP/IR Netcom can control 1 or more serial devices located virtually anywhere (via Ethernet or Internet), NetCom can be configured over Driver Panels, WEB Browser, Serial Port, Telnet or SNMP and serves as a transparent serial channel without platform and distance limitation. Housed in a sturdy metal enclosure including DIN rail mount, one to eight port models are available, 19in rack- mount versions with internal switch mode PSU can also be supplied. priced ta» HEnrejBinrfl □SI Ml 2 Oscilloscope ! Datalogger 2 "MS s Incut Channels + waveform generator output USB Instruments - PC Oscilloscopes & Logic Analyzers Our range of PC Instruments may be budget priced but have a wealth of features normally only found in more expensive instrumentation. Our DS1M12 and PS4QM10 oscilloscopes have sophisticated digital triggering including delayed limebase and come with our Easy Scope oscilloscope / spectrum analyzer / voltage and frequency display application software and our EasyLogger data logging software. We also provide Windows DLLs and code examples for 3rd party software interfacing lo our scopes. Our ANTS and ANTI 6 Logic Analyzers feature 8/16 capture channels of data at a blazing 5Q0MS/S sample rale in a compact enclosure. priced from £125 ( DS1M12 & ANTS ) 1 to 16 port USB to Serial Adapters Wilh over 16 different models available, we probably stock the widest range of USB Serial Adapters available anywhere. We offer converter cables, multi-port enclosure style models in metal and plastic, also rack mount units such as the USB-16COM-RM opposite. Serial interfaces supported include RS232, RS422 and RS485. We also supply optCHSolated RS422 and RS485 versions for refaible long distance communications. All our USB Serial products are based on the premium chipsets and drivers from UK company FTDI for superior compatibility, performance and technical support across Windows, MAC-OS and Linux platforms. priced from £20 £ U S232B/LC laptop Companion ) PCI Serial Cards Discover our great value for money range of multi -port PCI serial cards. Supporting from two to eight ports, the range includes RS232, RS422, RS485 and opto-isolaled versions. Our 4 port and 8 port models can connect through external cables or the innovative wall mounting COM BOX, EasySync Ltd 373 Scotland Street, Glasgow G5 8QB, United Kingdom Tel : 0141 418 0181 / Fax : 0141 418 0110 Web ; hllp: //wvvw.easysync .co.uk E-Mail: sales @easy sync.co.uk * Prices shown exclude PP and VAT where applicable 9/5005 - tiller d-drcmics 7 MAILBOX JTAG and the ARMee Board Dear Elektor staff — on the ARMee board K1 is connected to the primary JTAG pins or the Philips ARM. In order to use the JTAG interface on the ARMee board o few changes ore needed. Here are the changes and information on some specific issues you may have when using JTAG on ihe ARMee board. 1. DBG Signal. This signal is on pin 6 of K7, tl Is tied low by R20. In order to enable the primary JTAG pins or the Philips ARM chip, DBG must be high. So you need to fit a switch or jumper between the D8G pin and 3.3V. 2. nTRST Signal. This signal is on pin 3 of K 1 , Philips hove been o bit confus- ing about this signal. In their data sheet it is called TRST or nTRST in different places. The Chip Tuning for cars Dear Editor — I was very disturbed to read your article on Car Chip Tuning (july/August 2005]. To even mention the word "do-it-yourself in the article is highly irresponsible. Vehicle manufacturers configure their Engine Management Systems to ensure ihe engine components work within safe operating limits. It's one thing a well meaning amateur pay- ing the price of 'over-clocking' his or her CPU,, but quite another when a tamped EMS is sending seifdestructlon sig- nals to the engine while travelling at high speed down a motorway or autobahn! David A Jack [UK] We appreciate David's cautionary advice. Personally l am a slow and careful driver and l would not dream of ever messing with the electronics in my own car ( A J 997 Vouxhall Astra estate). However, as far as we know, there are legal limits to vehicle speed on public roads — not to torque and acceleration . MOT has the final word in respect of vehicle safety while complying with speed limits in any country is the car driver's own responsibility ; as is the decision to have a peek at a car's CPU system f if only on paper or for academic interest. JTAG standard name is nTRST because it is active low, ARM specifies this signal os driven by an open collector output. So it requires o pullup resistor. Philips say there is a weak pullup in the device but this is not generally sufficient in an electrically noisy environment. Therefore it is recommended you fit a 4k7 resistor between pins 1 and 3 of K1 . 3. RTCK Signal. This signal is on pin 1 1 of K1 . Philips say that RTCK must be high ot reset to enable debug. However this pin is normally an output so this can only be done with a pullup resistor. Whether you need this resistor depends on the ICE you use. Some ICEs do not use RTCK. Others have on infernal pullup. If you have problems debug- ging this may be something to look at. ICEs that do not sup- port RTCK may have problems interfacing to the ARMiTTDMl-3 at low clock speeds. The Func- tion of RTCK Is to stop the ICE sending data to the ARM faster than the ARM can read it (it is a handshake signal]. At low CPU dock speeds the JTAG dock rate must be slowed down, ICEs that da not support RTCK may be used as tang as their JTAG dock speed is set slower than one sixth of the CPU dock speed. 4. ICE Power. Some ICEs use pin 2 of K1 for their power (pin 2 is specified for shot purpose). On ARMee the 3.3V supply is provided by the regulator on the back of the processor board. St doesn't 8 have □ heatsink sa care must be take to ensure the regulator doesn't overheat. The simplest thing to do is plug in your ICE and feel how hot the board gets _ when it is tco hot to touch, you know that ICE is unsuitable for use with the ARMee board. 5, Stepping through code in Flash, The ARM7TDMI-S core has two hardware breakpoint units so debug software can set two breakpoints in code ot ony one time. Typically more than two are required so one of the breakpoint units is set up fo catch □ specific data value rather than a particular address and this special data value is used to replace the breakpointed instructions. When the ARM fetches the instruction, the breakpoint unit recognises it and halts the core. These are colled saR breakpoints and there is no limit to the amount that con be used. However to use this tech- nique in Flash, the debugger has to know how to write the Flash. Typically it cannot. The result of this is you can only place two breakpoints in Flash (because there are two hard- ware breakpoint units). By default most debuggers place breakpoints on a number ot exception vectors to catch things like data aborts. There- fore you need to remove these 'vector catches before there are any breakpoints left For your code. How you do this depends on which debugger you are using. Also stepping through code uses breakpoints — the technique the debugger uses is to read the instruction to be executed, decode it and work out the next PC value, then place a breakpoint on, that place. In short, if you want to step through your code to debug it, then either load it into RAM or load it into Flash and disable the debugger's vector catch breakpoints. Hope this helps everyone out there. Dave (on Elektor Forum) AUlt d edr Quia - 9/2005 F 8958252 Flash Microcontroller Board : December 2001, p. 54/ 010208-1 In general, it is best to no longer use the Micro Flash utility For I programming. AtmelISP is updated regularly and also works I under Windows XP. The configuration required tar the Elektor j Flash Micro beard is set up by selecting the option 'DK/jD'’ in I the opening menu. I i Simple Infrared Control Extender Juty/August 2004, p, 56, 030103-1 In the schematic diagram, transistor T1 should be a type j BD239, not a BD240. The circuit symbol is correct. I [ 1 I LFC210x ARMee Development System j April 2005, p. 20, 040444-2. J Guidance on the values of R24 and R25 settings of jumpers JP4-JP7 was unfortunately omitted From the article. R24 and R25 are pull-up and pull-down resistors taking a typical value \ of 390 O, JP5 is used to determine the effective resistance of | terminator resistor R25 in the RS485 interface. The resistor may 1 be left in circuit without problems. I The jumper settings are as follows; t Tv:o RS232 ports: JP4 - 2-3; JP5 = open; JP6 = 1-2; J 7 = 1-2. 1 Gne RS232 and one RS485 port: JP4 = 1-2: JP5 = dosed; jp6 ■ = 2-3; JP7 = 2-3, | With J4, JP 6 and JP7, pin 1 is marked by the bevelled edge. ^ There's more information an the ARMee board in our online Forum. i Thanks for ‘nor, Dave, we ere sure ire ARMee system gets even more power fir/ by the additions and extensions you have men- T o n eci . 1 h e pro j ect has g en era red a /of of interest not in the least by Tony Dixon's excellent support for if in our Forum and the tact that he plug-on CPU module is avaib able ready made through the Elektor SHOP. We now ca/i on our readers to send us their prac- tical applications for the ARMee board and so help to make the proiect even mare successful I Delving into Delphi Dear Jan — the articles Delphi for Electronics Engineers leak brilliant and I m sure Delphi is wonderful but at the college where I leach [North Sydney College of Technical and Fur- ther Education) we switched from Pa sco I to C quite a few years ago ond 1 can't get moti- vated to delve into Delphi. Would it be possible to re-write the articles to use Borland C Builder or Microsoft Visual C? If that's too big o job perhaps you could provide some shorter articles on getting started with C Builder. We don t use C Builder in our electronics courses at the moment but it would be good to Introduce It. (Most of our C programming is tar microcontrollers and we find the SDCC compiler to be excellent.) To motivate myself to learn Turbo Pascal graphics I wrote a program to design loudspeaker enclosures and equalisers, interested users may download it from my web site: hhp:/ /members, optus nsLcom. au/rwillson/ Thanks for a terrific magazine. Ross Willson (Sydney, Australia) Thanks Ross tor the feedback. We're currently negotiating with an team of authors to stage a course in C-h programming tor microcontrollers. The Delphi course should be finished by the November 2G05 issue. Deilef Overbeek and his fellow course writers have informed us that over 2,000 CD-ROMs have been sent ro Elektor readers all over the world I Elusive Phosphor-Bronze Dear Editor — In the July/ August 2005 issue, on page 72 [item 047) , I read that [phosphor bronze)... can be obtained from Conrad among other sources, In the form of small sheets../ . t have searched Conrad's UK website In vain tar this mate- rial pi ease can you fell me the entry you are referring to? I would dearly love to find a source of PB sheet for all kinds of jobs, I have been trying for ages!! Richard Barnes (UK) Unfortunately the stack reached by way of Conrad UK’s website is not (yet) os extensive as that of the German mother company. The matter has been brought to the attention of Conrad an sev- eral occasions but with little suc- cess sc far l he same problem exists in two ether countries E! ex- tor Is published in: The Nether- lands and France, r or nav- tne c a rent company’s website at www.conrad.de lists phosphor bronze sheet material as item nos 220659-iN and 220658-IN. Thin IPCB tracks Dearest Friends — I' m sitting with the new magazine (issue 7-8 2005) and cannot put it away But one thing caught my eye. The Energy-saving Switch on page 38 uses a 4-A fuse, but the PCB tracks are very small (thin). Maybe they will survive, but 1 would prefer copper tracks of two or three times the width you have designed. Klavs Rommedahl (Denmark) Absolutely riant. Klavs. these PCB tracks should he strengthened to about double the width we've shown. This is easiest done by shunting them with pieces of solid . insulated hookup wire. Mail Box Terms - Publication jf reader's correspon- dence s at re discretion of ire Ec tor. -V^ev. 'points expressed by cores- pondents are rot necessarily those of the Editor or Fob fisher. - Correspondence may be translated or edited for length ciarity and style - Whs nr reply. 1 "; to Maitho: carra span dance, piaase quote issue number. -Please send your MaJtBo, correspondence to: editor £ :: g cs c : ifi : r Bek tor E ectronrcs The Editor -O. Box 190. Tunbridge *Ve is 7\5 7\V l England 9/2005 - b/lcr sbtironTs 9 NEWS & NEW PRODUCTS Lightning strikes three times Lascar Electronics Lid. has added the EL-U5B-3 to its popular E L- USB range of standalone data log- gers. The unit has o Q-30V d.c. measurement range which enables users to measure and record outputs from a wide vari- ety of sensors such as pressure,, flow, pH, load and temperature. The unit is supplied with Win- daws compatible software which is used far configuration of the unit as well as download and graphing of the data. With the agger connected to o USB port, the software enables the user to set the required sampling raie (from 1 second) custom calibra- tion, high and tow alarms, and the logger start time. Once con- fig ured, the EL-USB-3 is removed from the computer, the cap is replaced, and the voltage to be measured connected to the lag- ger via two sc rev/ terminals. At this point logging can com- mence. Two LEDs indicate when the unit is logging, when an alarm level hos been reached, when the bat- tery needs replacing or when the device has reached full memory capacity [32,000 readings). To download data the user recon- nects the unit to the USB port. The supplied software is then used to download and graph the data from the unit. Data, saved in Jxl format, can be imported to many industry standard spreadsheet packages for mare detailed analysis. The EL-USB-3 is available immedi- ately From Lascar Electronics at o price of £39.00 (£23.40 in OEM quantities of 250+j. To order now, coll -5-44 (0)1794 884567 or order online at www.la5carelecfronic5.com . 2 low-cost Picoscope 2202 Pico Technology hos announced the immediate availability of the PicoScope 2202 PC Oscillo- scope. Connected to your PC and powered by its USB 2.0 part, the dual-channel PicaScape 2202 is a PC Oscilloscope with 8-bit resolution, 20 MS/s som- oling rare and a 32kB memory depth. In combination with the PicaScape and PicoLog software included the unit acts as on oscilloscope, spectrum analyser, multimeter and data logger. Using the latest advances in measurement technology, Pico Technology has designed the low-cost PicoScope 2202 with hobbyist and educational mar- kets in mind. With its high sam- □ling rate, the oscilloscope is useful in a variety of electronic applications including audio amplifiers, swifched-mode power supplies and microcontrollers, and for displaying waveforms obtained from laboratory exper- iments. The USB 2.0 port mokes the device easy to use with all standard desktop and laptop PC's and removes the need to configure printer ports. There is no need tor an external power supply, as the unit fakes its power from the USB port. The PicoScope 2202 is sup- ported by the PicoScope ond PicoLog software included with each unit, PicoScope provides oscilloscope, spectrum analyser and multimeter functions with the ability to save and print waveforms. PicoLog turns your system info a powerful data log- ger that can export data to a spreadsheet or display it os a graph, bath in real time or using recorded data. These programs are easy for the novice to oper- ate, but also contain □ full range of advanced features for expert users. Software updates are available tree of charge from ihe Pico Technology website. The PicoScope 2202 PC Oscil- loscope is available immediately direct from Pico Technology or from one of our authorised dis- tributors at a cost of £199 + VAT. You can obtain further informa- tion from the Pico Technology website a! w-.v w. p i co f ec h . co m or by calling *44 (0) 1480 396 395. 10 eSsSitcr a'=m&mcs- 9/2005 Handheld through-wall radar Cambridge Consultants is previewing the second generation of its through-wall radar technology, which is expected fo break new ground in quality of imaging and ease of use. Providing 3D feed- back on the location and movement of people inside buildings, the system is being reengineered as a standalone handheld unit, and will be offered In a slimline case with its own colour display. The new version of the radar, Prism 200. is hoped to eliminates the need for an external con- tra ler and man-machine inter- face. This is achieved by integrat- ing a Video Core processor which combines high-performance dig- ital signal processing capabilities with a versatile display driver. Results are presented instantly on the units built-in 6.4-inch colour display - or alternatively, trans- mitted to a remote laptop. Building on the success of the first-generation Prism 1 00 radar the new radar will offer features that will enhance the efficiency and safety of military and emer- gency service personnel in situa- tions such as hostage taking, search and rescue. Held against a wall or mounted on a tripod up to 2 metres away. Prism 200 transmits lav/ fre- quency ultra-wideband (UW8) radar pulses that pass through building materials over 40 cm thick, to detect activity over o range of up to 15 metres. A unique feature of the new intelligent radar core is an array of antennas which gives ii a large field of vision — at least 140 degrees in both vertical and horizontal planes — combined with 3D object location ond motion tracking. Operators can use the 3D capability to decide whether people are standing, sitting or lying or whether ihe object detected is human or an animal. Prism 200 will he able to provide plan and elevation views. The onboard signal processing may also be customised to suit a wide range of target applications. Programmable parameters include range, scan rate and target permanence, ond ihe display can be adapted far optimised presentation of the data for specific uses.. The system identifies an individual person as a cluster of targets of the same colour to give a clear representation of the movement of each person in the space being monitored. However, much more is possible including the ability to focus on living/movina targets to give a tracking history of individuals and to build up a picture of the static objects in the roam, Cambridge Consultants is now at an advanced stage of develop- ment with the radar care, and is designing a tough weatherproof case to house the system. The fin- ished product is expected to weigh around 3 kg, including a lithium-ion battery pack that will stare enough power far around two hours of continuous use. Fea- turing a slimline shape with hand grips, the unit will be easily portable by a soldier or emer- gency service worker. And, it can be put info use almost instantly: all that s required to start monitoring Is o single push of a button, with ihe embedded system displaying results within 2 seconds. Cambridge Consultants Ltd, Science Park, Milton Road, Cambridge, CB4 ODW, UK. Tel: +44 (0)1223 420024; Fax: +44 {0)1223 423373; www.CQmbridqeconsultant5.cam ■;j57l3 -2 UltraCMOS technology tops 1 3 GHz Peregrine Semiconductor Corpo- ration, a supplier of the indus- try s most advanced RF CMOS and mixed-slgno! communica- tions lCs r recently announced that its leading-edge UltraC- MOS"' pro csss technology is producing products that now reach 13,2 GHz, a speed level! never-before attained by tradi- tional CMOS processes. The FE9308 Rad-hard Prescaler, designed for space,, high-perform- ance military and infrastructure applications, is the first CMOS device to operate in X and Ku Band showcasing the UHraCMQS speed advantage. This new Pere- grine Prescaler Is claimed to deliver industry-leading RF performance at X or Ku Band on CMOS. The PE9308 also reaches an ultra-low- power milestone, oper- ating at 25mA (iyp.) @ 2.5V — which is about ]/10ih the power cf an equivalent GaAs device — yet delivers decidedly superior rad-hard performance, including fixed divide ratio of 4; low SSB phase noise; immunity to Single Event Latchup (SEL); Singleevent Upset (SEU) of less than K> 9 errors/' bit-day; and tolerance total dose radiation of 100 Krads (Si). Additionally, output frequency con be fed directly into Pere- grine's complete line of PLU, offer- ing a complete frequency synthe- sis capability, rram DC to Ku band entirely from the Peregrine portfolio. This reduces purchasing ond vendor management far all frequency synthesis designs. Evaluation Kits support develop- ment with the devices and Ultra- CMOS technology tutorials are available from Peregrine on its website at v aw/. psemi.com. The PE9308 is offered in the 8-lead Formed Fiat Pack or die. and h in production now. . 2 '-: -- S •3DQ5 - efeVlcr e'sctrcnks n Paui Goossens The Xbox made by Microsoft is a very popular games console. What many buyers don't know is that the Xbox is really just an ordinary PC running a special version of Windows. This leaves the door open to experimenting for example with Linux. But first you have to get round a couple of modifications, which for many is all part of the fun. So let's get started! A s with most games consoles the Xbox has a built-in protection that prevents the illegal copying of games. A disadvantage for the con- sumer is that the making of backups of expensive games is not possible or pointless, since the games console refuses to play these copies. Apart from that, many engineers would like to know how this device works and if it can be used for other purposes. There are always some hobbyists who use their spare time to investigate how to get round this protection, Microsoft has also included this protec* lion in the Xbox, So there's work to be done... PC Iook*aiike When the Xbox was examined it soon became clear that the technology used came straight from the PC. This shouldn’t come as much of a surprise, since Microsoft has concentrated on the PC during most of its lifetime. The CPU. the graphics processor and all other components are the same as those used in a PC. A DVD player, hard drive and network connection are included as well! The idea to run Linux on such a games console is then just a logical conclusion When you consider that Linux is the biggest competitor of Microsoft, you know that the battle lines are drawn... Broadly speaking, the protection m the Xbox consists of two parts. The first Protection 12 cln.f'i'i clErtTurici - 9/ 2 C j 5 refuses to run programs that haven't been digitally signed by Microsoft. Hie second protection is that the hard drive is normally ’locked'. Whenever a read or write operation takes place, the drive is momentarily 'unlocked'. This makes it impossible to remove the hard drive and to read or modify its contents from a PC. To make life even more difficult for the backers, the hies are stored in a differ- ent way called the xfilesysiem. And finally, there is a new hie format for programs. These files now end in .X3E instead of .EXE, as used on the PC, The structure of the file has also been changed, so that a simple renaming of the file Is not sufficient. These days there are many ways in which to get round this protection. It's all very different in the Xbox. Hie BIOS first sets up the hardware, but it also contains the operating system, (This operating system is derived from Windows 2000), There is nothing left of the operating system on ihe hard disk. The routines that check that the pro- grams are digitally signed by Microsoft Booting up The biggest difference between the PC and Xbox is the way in which they boot up. The PC contains a BIOS (firmware) that doesn't do much more than set up the hardware and load a hoot sector into memory. When this is executed the operating system is loaded. are also contained in the BIOS, as are the lock and unlock routines for the hard disk. There are two ways in which to get round these protection systems. One solution is to use a loophole left in the protection by Microsoft. Another is to adapt the BIOS. This also requires a Figure 1. The Xbox in oil its glory! 9/2005 * electrics 13 HANDS-ON XBOX MODDING modification to the electronics of the Xbox. As an electronics magazine we obviously looked at the latter option. Modchip The BIOS inside the Xbox determines what software is being run and what not. To be able to run Linux, it is nec- essary 10 install 'foreign' firmware in the Xbox. This second BIOS is usually added as a separate chip to the exist- ing hardware. There are special 'mod- chips 1 available for the purpose. These are small boards with a number of components that change the function- ality of the Xbox. All required connec- tors are usually included. Xbox owners should note that the product warranty is voided when the box is opened! The hardware itself is quite refined. Thera are two Cash chips, an FPGA and a handful of smaller components. The reason for the two Sash chips becomes clear when we look closely at the specifications for the modchip. One of its features is a backup BIOS. The flash chip can be programmed by the user, but if something should go wrong the modchip can be quickly restored to working order from the backup. This could be a common occurrence, espe- cially when you're not completely sure what you’re doing. The BIOS in the backup memory is a 100 b open source BIOS (called Cromwell). This part of the memory can be protected via a switch from overwriting and can be turned on at any rime. Cromwell Tne Cromwell BIOS is a versatile BIOS, It adds the capability to program the rest of the flash memory of the modchip. This Is easily achieved via a network cable. From the PC you can use either a web browser or ftp pro- gram to control the programming If this doesn't work for some reason, you can also program a new BIOS via a CD. Apart from these useful tools to pro- gram the hash memory, the BIOS can also collect many details regarding the Xbox, It can report back which graphics chips are ins t abed, how much memory is on board, etc. We have yet to tell you the most impor- tant feature: this BIOS permits the use of programs that don’t contain a digi- Modchips: sales illegal — installation legal? Figure 2, The built-in Xecuter 3 modchip is connected on the left-hand side to a header. At the front on the left-hand side is the accompanying bracket, which is used la Install the chip. ial signature from Microsoft! For those of you who ' d like to use this BIOS ro play copies of your games, we have bad news: the playing of back- ups. as well as original Xbox games, is not possible with the Cromwell BIOS, by computer nerds and Unix experts. Nothing is further from the truth! This is especially so when you use a goad dis- tribution (of Live CD), which comes as standard with a graphical user inter- face (GUI). Enter Linux Fortunately it is possible to use Linux In combination with the Cromwell BIOS. This requires a special Xbox Linux version, such as Xebian [1 j. It is derived from Debian Linux. It is very easy to try out this version of Xebian: Linux for Xbox The Xbox Linux Live- CD used here is set up round a GUI and has a very intuitive interface. People who are used to Windows won't have many problems to start and use applications. The Live CD already contains a num- ber of programs. A web browser and email program are of course included. There is also an Office suite with a word processor and spread- sheet program. Once Linux has been installed on the hard disk, it becomes pos- sible to install and use all Linux software. the Linux distribution, since a Live -CD is available as a free download. Turn on the Xbox with the CD in the drive and also make sure that the Cromwell BIOS is turned on. Xebian ■.‘.ill then start from the CD, and after it has finished booting you can use Linux straight away You couldn’t be more wrong if you still believe that there is only a limited range of software available for Linux. By now thousands of programs have been written for Linux. It’s very likely that all programs you've used so far under Windows will have an equiva- lent under Linux. What can I use it for? People who aren't yet familiar with Linux are often reluctant to use a com- pletely new operating system. It is a wide held belief that Linux Is a com- plex system ihat can only be operated You can configure the Xbox as a multi- media system in the same way. Just add the required software and it will run. It can also be used for many many other purposes. After all. the Xbox is just like a PC! 14 skhoF dedroniB - 9/2005 Xbox: cheap multimedia system running Linux Figure 3. The madded Xbox in action {running the Live version of Xebian). There are other ways in con frost, ihe manufacturer SONY ha; been actively involved in moling Linux available far its Playstation. There are Linux distributions far sale for both the Playstation and the PlaystatEon2. The Playstation needed some extra hard- core as well, including an interface for the keyboard, a VGA adapter, eta. The chances that Microsoft will do something similar for the Xbox seem ta be very remote... Xbox 360? As you may be aware, Microsoft has been busy with the successor to the Xbox, the Xbox 360. When this is released It's very likely that the old Xbox can be picked up at bargain basement prices. If you are looking for a cheap multimedia system, we suggest you add an 'old' Xbox ta the list An advantage of the Xbox Is that if is still a games console which has a large num- ber of games available for it. Playing Backups The Cromwell BIOS is not capable of ploying Xbox games, whether they ore originals or copies. This can only be done with an illegal BIOS. These Illegal BIOS chips are all copies of the anginal Microsoft BIOS, the main difference being that ihe software that checks if a program contains a digital signature from Microsoft has been removed. (Il)legal? We asked a lawyer to Investigate a few things tor us. We wanted to know what is and what isn't permissible. For exam- ple, jr the US of A you are allowed to make modifications that enhance the functionality of devices Is this also per- missible in Europe? You could look of o similar situation with cars. There ore almost no cars that can't go faster than 70 mph. In other words, nearly every car Is capable of Illegal speeds. It is left to you, the user and/or owner, whether you choose ta do so. You could reason along the same lines when mcdding the Xbox. You give it a new function that could be misused (copying). In the UK and most other European countries as owner you are not allowed to make a backup copy of your software. IF, for example, a legal copy of a game on CD-ROM is damaged for some reason, based on the product warranty you may be eligible tar a replacement copy from ihe supplier. So what about ihe modchips? The UK High Court hos judged that “the sale, advertisement, possession for commer- cial purposes and use of Playstation modification chips is illegal in the UK [21 July 2004]. This should apply to the Xbox as well. In ihe USA, the appli- cation of the Digital Millennium Copyright Act In 2003 resulted in five months jail and a 28,500 dollar fine for o trader selling Xbox modchips on the Internet. Having □ modchip Installed or commis- sioning to do so Is considered aiding and abetting, or Inducing ta commit on offence. According to copyright lows, adding new functionality ta software is only allowed If you have obtained written permission from the copyright holder. This also applies to software (firmware) burned into some certain hardware, as is the case with integrated circuits. Although not strictly mentioned in the UK High Court ruling, fitting an mod- chip in, say, a Sony Playstation, Is like- ly ta be illegal, too, as It allows illegal- ly copied games ta be played. This fol- lows a recent verdict of the US Supreme Court that holds makers of peer-to-peer software like Kazan responsible for possible Infringement of copyright by users exchanging Illegal music fifes — although, of course the some programs also allow perfectly legal files to be shared, too. However, installing □ modchip does not add anything ro the existing software. Rather, other software 'also' runs, optionally and in parallel, ta other words, no changes are made to the original software. Although selling mod- chips is Illegal, it can be argued that the installation of a modchip in an Xbox by the rightful owner (of the Xbox) is not a violation af the copy- rights owned by Microsoft, Based on ownership rights but still observing the bounds of higher legislation you have the right to modify, damage or even destroy the unit to your heart's content. However, if, by accepting Microsoft's Xbox User Conditions, you have prom- ised not ta mess with the unit, you may, just In theory, be held liable for con- tract breach. Interesting links: [1] This site contains several Linux dis- tributions. Keep in mind that some downloads exceed 1 00 MB! y/v.w, X box-1 Inux-ora 15 lints* -tudb-Lilu aMirin your own irhfctilse' or e cancel fat Pori ine!op^|tlon micros channel rjf uinmun. Ji ti D^P umi aJ/iiU? I O f ! u US $399 S (UK £230} iiuu 'Jatays m •J'liimiijlsj r-t!=j yju jjy iirlz-dd For moro information / 1 : o.oom p^aiKw 'rr-s at; VW.v.acitilfa.com, n. pi® 1 Number One Systems The world beating PCB design software . •• ■ $*' - -i 3 V • Easy-PC version 9 just gets better Winning accolades the world over. Easy-PC for Windows V9 is another major milestone in the evolution of this extremely popular software tool. 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See inside your circuit with simultaneous analog, logic and spectrum displays to make I racking down those elusive real-time bugs much easier BitScope combines a high speed synchronized storage scope ana logic analyzer with a programmable waveform generator and spectrum analyzer BitScope DSO software for Windows and Linux BriScope's integrated design uses standard oscilloscope probes acd a growing range of custom probes to provide functionality equal to instruments many times the price. BitScope plugs into third party software toe's and res an open API for user programming and custom data acquisition. I Get the full picture with BitScope I Mixed Signal Oscilloscopes With ' Smart POD : connected active probee and multiple software options you've got the perfect low cost high performance test and debug solution! 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Capture circuit response simultaneously on BNC A BitScope i c-j Lmai6x>^::>u -r- ■ 31 - — 9/2005 - elekfcr el-tiicrics TEST USB OSCILLOSCOPES In the past, a lot of space in hobby rooms and work sta- tions was taken up by an instrument in a large case with a small screen, but now many of its functions can be performed using a PC. A small box can transform an ordinary PC into an oscilloscope with extensive functions. Elektor Electronics subjected eleven of these "USB oscilloscopes' to an extensive evaluation. Jan Steen Oscilloscopes have become essential measurement instruments in the electronics world. In the early days, they were simple, massive cabinets with a limited frequency range and a single measurement channel. After that came the multichannel versions. Digital storage oscilloscopes appeared on the scene even later. They made it possible to 'freeze’ a certain image and store it in memory. The more luxurious versions some- times included a small built-in printer so stored images could be printed out for inclusion in measurement reports. Thanks to progress in electronics, the cabinets became steadily smaller and lighter and the maximum measurable frequency rose higher and higher. Manufacturers of measurement instruments also developed oscillo- scopes with the dimensions of a hefty multimeter fitted with an LCD screen, which made them suitable for portable use. All of the above-men- tioned types are still commonly used. The PC as 'my man Friday' PCs have come to be standard fea- tures in every house and office. They have also become essential in the electronics world. For instance, PCs are used for drawing schematic dia- grams of electronic circuits, simulat- ing circuits, and making PCB designs. They're also very convenient in the lab. An application in which the PC forms part of a measurement system is thus an obvious idea. USB oscilloscopes It doesn't take much imagination to think of combining a sort of A/D con- verter with a PC to ob serve all sorts of signal waveforms, which practi- cally amounts to the same tiring as an oscilloscope. Various types of adapters are available for this pur- pose, ranging from cheap to expen- sive. Here we decided to see what was available in this area with a USB interface, because we'd like to keep up with the times and serial ports are becoming increasingly less common in new PCs. With this sort arrangement, the PC 13 e!:her n-’fronh ■ 9/2005 actually only serves as a data pro- cessing and display system for sig- nals measured using the adapter, which forms the heart of the USB oscilloscope. The adapter contains the components (preamplifiers and attenuators, A/D converters, memory and USB interface) that process the signals to be measured and forward the measurement data to the PC via the USB port. The associated soft- ware processes the received data, and the results are then displayed on A bit of nostalgia I can slill remember quite well the impression the oscilloscope made on me as a lower general secondary student during an opemhouse visit to the intermediate technical school. Various measurement configurations were set up in the electron- ics fab,, and the oscilloscope formed the centrepiece . When I saw it, I thought: '111 never learn all of that'. But in practice it turned out fa be a lot easier than I expecied because an oscilloscope isn't such a complicated instrument It basi- cally consists of a cathode-ray tube with horizontal and vertical deflection plates. An internally generated sawtooth signal is usually applied to the horizontal deflec- tion plates. The frequency of the sawtooth signal determines the timebase. That means that when you turn the timebase knob in principle aft you do is change the frequency of (he sawtooth signal The electron beam moves from left to right across the screen. If no signal is applied to the Y input and! the timebase is set for a very slov/ trace, you can see whaf the saw-tooth signal actually does: you see a spot moving from left to right across the screen. If you gradually reduce the time base (by increasing the sawtooth frequency), the spot moves faster and faster until it fina iy becomes a line instead of a spot. The connections to the deflection plates are represented on the front pane! as the X and Y inputs. The signal to be meas- ured (such os a sine wave voltage) is applied to the Y input. Aside from 'normai operation with an interna! sawtooth signal applied to the X input (internally) if is also possible to apply variable signals to both inputs. That produces fascinating elliptical patterns that constantly move and rotate arid give a rather futuristic impression, which are commonly known as Lissojous figures. the m onit or. Here we have a very generously sized display at our dis- posal, especially compared with pre- vious instruments. The display for the measured signal is complemented by a complete graphic user interface with all the front-panel controls we're used to from a real' oscilloscope. Comparison of selected models We selected eleven of these 'USB scopes' and subjected them to criti- cal ex amin ation for you. The results are reported on the fallowing pages. Tills does not amount to a thorough study but instead more of a presenta- tion of the most significant facts and features. We examined aspects such the quality of the construction, the associated software, ease of use, and technical specifications. These are all practical aspects that can help you select a USB oscilloscope for your own use. Incidentally, there are also PC oscil- loscope adapters that can be used with a parallel or serial port, but we left them aside for the time being. Many PC users are quite rightly enthusiastic about the USB port due to its communication speed (partic- ularly with USB 2,0) and convenient hardware installation. What are the important characteris- tics of a USB oscilloscope? For many users, the maximum measurable fre- quency is an important considera- tion. However, in the case of digital oscilloscopes (which includes USB oscilloscopes) the actual characteris- tic is not the maximum frequency, but instead the sampling rate. With an oscilloscope, sampling simply con- sists of taking measurements a cer- tain number of times per time unit. All sorts of sampling rates are possi- ble, but most devices have a value between 5 MHz and 100 MHz, In the- ory, sampling yields a series of points. Tire software joints the points to form a line, such as a sine wave. This is called Te construction'. The maximum measurable frequency is thus not the same as the sampling rate. A rule of th umb that is often used is that the sampling rate must be at least twice the frequency of the input signal to be measured. How- ever, reconstruction of the signal waveform is not possible under these conditions. There are also a number of tricks that can be used, such as oversampling, but that's something we'll come back to further on. We primarily examined the devices we tested here as USB oscilloscopes. However, some of them can also be used as voltmeters, spectrum analy- sers or even function generators. 'USB oscilloscope' is thus perhaps not quite the right name. One of the manufacturers, for example, uses the term "multifunctional PC measuring instrument'. Tnat's actually a better description of the functionality. A table summarising the principal characteristics of each of the devices is provided at the end of this article. It provides a handy aid for selecting the most suitable solution for a particular measurement situation. But first, let's look at our practical experience with the eleven USB oscilloscopes. 9/ 2005 - ilslbJ elctirouitt 19 TEST USB OSCILLOSCOPES rare and trigger level so the measured signal is immediately displayed in an easily viewed form. It probably goes without say- ing, but she images can be stored and printed. You con also operate the instrument svith channels 1 and 2 in sum or differen- tia! mode and so on. The ability to use crosshairs cursors is also very handy. They can be used to make measurements between two selected paints in the image [time difference, voltage difference etc.) The results of the crosshair measurement are displayed in a small window. All in all, the Handyscopes are very com- plete instruments with matching perform- ance. TiePie Engineering in Sneek, The Nether- lands. has specialised in PC measurement instruments for many years already. We received two USB oscilloscopes bearing their brand name for our tests: the two- channel Handy scope HS3 ond the four- channel Hondyscope HS4, The two instru- ments have a lot of similarities with regard to construction and software, but they dif- fer in several aspects. Besides the oscillo- scope functions, the Hondyscope instru- ments provide voltmeter, transient recorder and spectrum analyser functions. The HS3 also incorporates a function generator. It can generate sine- wove, triangular-wave, square-wave, white noise or arbitrary sig- nals defined by a data file, all up to a max- imum frequency of 2 MHz. The output sig- nal con also be swept between two config- urable frequencies. Naturally, the amplitude (0-12 V) , DC offset and symme- try of the signal are adjustable. We also took a brief look at the spectrum analyser, which computes the frequency components of the input signal and displays them on the screen. A 1 4 -MHz signal from a short- wave receiver was imaged quite nicely. Installation The software is provided on a CD-ROM r along with the user manual, but everything can also be downloaded from the TiePie website. The first thing we did was to connect the Hondyscope to the USB port. We then installed the USB drivers followed by the application software. After the PC was restarted, everything worked right off the bat. Oscilloscope Around 90% of the controls will probably be intuitive for a competent electronics type. The rest require briefly consulting the man- ual. The image corresponds to the typical display of a digital oscilloscope. The sam- pling rate and record length, among other things, can be set under ibe 'Timebase'’ menu. If the sampling rote and record length are configured properly, outstanding images are displayed. A handy feature is the auto setup' function, which automati- cally configures the input range, sampling Multichannel Besides the standard software, a "multichan- nel'’ version of the software can also be downloaded from the TiePie website. This software is □ beta version, but W is certainly worth mentioning. It allows several instru- ments to be used a the same time. Several HS3 and/or HS4 units can be linked together, which makes i! easy So implement an instrument with 32 parallel channels. If so desired, operations can also be per- formed on the measurements before they are plotted on the display. Specifications The two instruments are very similar in terms of construction, software and use. The HS3 has two channels and is available in vari- ous models with maximum sampling rates of 5, 10, 25, 50, and 100 MS/s. The bur- channel HS4 is available with a maximum sampling rate of 5 r 1 0, 25 or 50 MS/s, A I¥/10¥ probe is supplied far each chan- nel with the HS3 as well as the HS4. Each instrument has a USB 2.0 interface (com- parible with USB 1.1) and a configurable ADC resolution of 1 2, 1 4 or 1 6 bits. Besides the two measurement channels, the HS3 includes a function generator, as already mentioned. Conclusion It's o pity that lack of space prevents us from listing all the options and features (which is aiso true for the other USB instru- ments), bur these USB oscilloscopes from TiePie are truly 'top end and would be a welcome addition to many an electronics bench or hobby roam. They ore simply out- standing, versatile instruments. i « ^ P - » ^ V i ^ A* 1L ' - i jmsavm'. c -«r , j' TriT^d ! DC_ 1 1 j 3*1 r r 3 iC' OVt CfTitfiaf ChKOD Vpc .fiii £?. GSvCilI IujjuC kHz F -nar-fl 3 i n ia u ia& t u 1 J 3 I ** i i n -are -« ^ _ n ij r - - | r . 3 1 ■J " 3 -flJ *i K ^ _eJ 20 ebklor derticmts- 9/2005 We fried out two models from this brand. The firs! one is a 'norma!' USB oscilloscope: ihe D$ 1 f'A 1 2 Stingray. The second one is a pen scope': the PM40M10 Swordfish. In contrast to the two TfePie Instruments, these two PC Instruments from USB instruments bear no resemblance to each other. The application programs and graphic user interfaces, on the other hand, ore practi- cal!;/ the same except for a few details. Stingray This might be called a 'starter model'. The Stingray is o good two-channel instrument, but it has major limitations with regard to the maximum measurable frequency. The manufacturer specifies an analogue band- width of only 250 kHz. Besides acting os an oscilloscope, it can serve os a data log- ger and function generator, ana if has FFT capability (like the Handyscopes), TFT stands for Tost Fourier transform , which is a type of spectrum analysis. In an FFT dis- play, frequency is shown on the horizontal axis instead of time. With the shortest time- base selling of 2 ms f ihe X axis of the analyser extends to 500 kHz. The Stingray has a sampling rate of only 1 MS/s in normal operating mode hui the ADC resolution is a healthy 12 bits. A sampling rate of 20 MS/s can be achieved by oversampling. However over- sampling con only be used with unvarying (repetitive) input signals. In the oversam- pling mode, ihe software measures the input signal at a different time during each cycle and then combines the results. This amounts to a software trick to enhance sampling of a signal that cannot be prop- erly reconstructed using direct sampling. Incidentally, it works quite well. The Stingray is supplied with a handy carry- ing case far convenient transportation io where it is to be used. Stingray software The software is supplied on a mini CD- ROM. Installation is easy. After the CD is Inserted, a menu Is displayed to allow various options to be selected. That involves the software for the 'scope, the software for the data logger the manual, and so on. there are also Linux drivers on the CD-ROM, The Stingray in practice The instrument is easy fo use, and the man- ual Is actually not even necessary. The graphic user interface looks very much like a norma: 'scope. St s amusing to watch the virtual knobs turn when you select the 'auto- set' option to automatically search for the best settings for displaying the signal. That allows you to spend less time spinning knobs and mare time doing useful work. Of course you can always adjust the settings (to Increase or decrease the number of dis- played periods, for example). Swordfish This Is something quite different. It Is a handheld measurement pen, or pen scope'. Although it comes from the same manufacturer, it has completely different construction ond specifications. It also comes with a nice carrying case. The Swordfish is a combined oscilloscope and data logger, so it does not have a function generator output. However, If dees have a considerably higher sampling rote than the Stingray. The Swordfish has an ADC reso- lution oi 10 bits. The sampling rate is nor- mally 40 MS/s, but that can be boosted to 1 GS/s using oversampling. The analogue bandwidth is 5 MHz. That means you can measure significantly more signals with the Swordfish than with the Sting roy. It also has FFT capability that is iied to the rlmebase setting. In addition,, the Swordfish has a button on the probe that can be used to 'freeze ihe image. The tip of ihe Swordfish is attached using a Cinch connector and can easily be removed,. A BNC adopter can then be plugged Into the Cinch connector to allow a regular probe to be connected. Swordfish software The software tor ihe Swordfish is also sup- plied on a mini CD-ROM. The installation ond menu are practically the same as for the Stingray. The graphic user interface dif- fers slightly from the Stingray interface, but that is because the Swordfish is a single- channel instrument. Conclusion These are two different instruments, each with Its own specific application area. Both instruments feature a convenient user inter- face (which unfortunately cannot be resized) and easy-to-use software v.jlh Linux support. The screen colours are config- urable, The graticule can also be illumi- nated. All in all, these are fine instruments with matching software. 9/2005 - sisklor efitf ranks 21 TEST USB OSCILLOSCOPES PenscopeDAQ The Penscope DAG from RK Systems hcs fairly go ad specifications. Its packaging looks o bit amateurish, but ii has a maximum sampling rate of 100 MS/s, an analogue bandwidth of 20 MHz, and a 1 28-KB data buffer. The 8-bit ADC resolution is somewhat less than that of some other instruments, such as the Handy sc opes and the Vego instru- ments. This instrument also has □ voltmeter function and FFT capability. It is actually a p ro beTy pe i n strume n t, just li ke i he Swo rdri s h . Unfortunately in this case the probe head is not removable, so you'iil have to improvise if you want to connect a regular probe to it. Software Unfortunately, the supplied mini CD-ROM does not start automatically, so you have to open the folder and run the exe file manu- ally The rest of the installation process Is straightforward. The manual is supplied as a PDF file on a separate CD-ROM, and St is also present on the PC after the software has been installed. In light of the non intuiiive operation of the instrument, the manual is certainly not an unnecessary luxury. Practical experience That's a story in itself. The graphic user inter- face is not particularly easy to understand at firsT. Although It looks quite professional with regard to presentation r differs quite □ bit from what we re used to from 'normal oscilloscopes and other USB scapes. It thus rook a fair o mourn of time before we started to get the idea. It also takes quite long for the image to be formed, ana we found the absence of timebase and input sensitivity knabs a bit inconvenient. Although there are other J knobs' for this purpose, it's not oil that obvious how to use them. We would rather see virtual knobs corresponding to what we’re used fo from normal oscilloscopes. Conclusion The Instrument dees not have a particularly professional appearance. It also does not allow other measurement accessories to be fitted. That means you have to do every- thing with the probe tip. Although the graphic user interface has a professional appearance, she non-standard controls fre- quently make it necessary to puzzle our how to use them before you can make measurements. PicoSeotoe 3205 Picotech offers a broad range of electronic measurement equipment. The cose of the PicoScope 3205 is somewhat larger than what we've seen so far with the other instru- ments, but it Is still a compact device. Besides operating as an oscilloscope, the PicoScope 3205 con be used as a volt- meter. spectrum/FFT analyser, date logger, and signal generator. The specifications are quite respectable. The 3205 is a profes- sional instrument. The normal' sampling rate is 1 00 MS/s, and □ rate as high as 5 GS/s can be achieved using oversampling. The analogue bandwidth is 1 00 MHz (which Is actually only usable with oversampling], and the spectrum analyser has a range up to 50 MHz, The 3205 has 8-bit resolution and a 1 -MB memory buffer. The signal genera- tor can produce sine-wave, triangular and sawtooth signals up to a maximum fre- quency of 1 MHz. li can aha be operated in swept mode, which nicely rounds out the picture. The unit provides two measurement channels. They can be configured to meas- ure signals and write data in alternate' or 'chopped" mode. Software and user interface Installation of the software from the supplied CD-ROM is entirely straightforward. Every- thing works the way it should right ofi the bar. The user interface does not have virtual knobs but instead primarily uses pulldown menus. However, everything is very intu- itive and we managed to put the instrument through oil its paces in practically no time. An especially nice feature Is the ability to display the some signal in a new screen with different settings such as a different time base or different input sensitivity. The colours can also be freely configured. Conclusion We can certainly say that this is one of the better instruments in our selection. We liked everything about the PicoScope 3205: the software, performance, screen Images ease of use, ond construction, just about anyone who works with electronics would be very' pleased with this instrument. 22 efiktw eicClronics -9/2005 ITC i!5_ Ths M522 is made by the Slovakian com* pony ETC. The M520 line consists or lour models or USB oscilloscopes ,vlih rhe des- ignations M521 through M524. The first two models are 6Q-MHz versions while ihe btter two are 1 20-MHz versions. The M522 is o fwo-chonnel instrument with an additional output for an external trigger or square-wove generator [rcr probe calibra- Kan). Incidentally, most scapes also include this ieafure. Like all or the previously described scopes, the unit is compatible with USB 2,0 and USB 1.1 and it bos a bandwidth of 60 MHz. The sample rate is 50 MS/s in normal operating mode or 5 GS/s with oversampling. Besides the oscilloscope function, the M522 con open ate as a spectrum analyser. According to the specifications, the maximum permissi- ble input voltage [except on the trigger input) 15 ±200 V at i 00 kHz. That's quite a bit. Not oil USB oscilloscopes can tolerate such high voltages. Software and operation It s beginning to sound a bit boring : but here again there weren't any installation problems. All of the steps are clear, and we cou Id start using the M522 within o few minutes. The control pane! appears So be quite a hit more complicated than whot we've 5een up to now, but it can still be regarded os user-friendly. The graphic user interfaces shows a large number of little knobs and buttons, but you can gel quite a ways with o bit of playing Ground. Practical experience As we already said, it takes a bit cf getting used to, with on occasional look at the manual. However, operation is still user- friendly. and we always ended up where we wanted to be. The link between the time base and the analyser is a bit Incon- venient, because the analyser window dis- appears every time the time base is adjusted. It's thus better to use ihe scroll button fo adjust ihe X-axis setting of the analyser. Here again, oil of the colours are freely configurable. Conclusion A nicely made instrument. Good specifications and performance. Unfortunately, there Isn't any built-in function generator (except far a simple square-wave signal), “re user in ; e dace is very comprehensive and has a professional appearance. If you only need a combined 'scope and spectrum analyser and the signals to be measured lie below she maximum fre- quency limit, this instrument is certainly a good choice [with she option of choosing the M523 or M5 2 3 ter greater bandw'dih). This oscilloscope from Voltcrart is one of pair of instruments. Its J big brother' bears the name DSO-2 1 00 USB, but it was unfor- tunately not available when we did our test- ing, The DSO220 is thus the entry model , and In Sign - of its maximum measurable fre- quency it Is perhaps intended primarily for the hobby market. It has a sampling rate of 20 MS/s and 8-bit resolution. We didn't see any mention of oversampling, but ihere are hvo forms of signal scanning called sampled’ scanning and 'linear' scanning. The latter seems to have o certain resem- blance to oversampling. The Y-axis sensitivity setting ranges from 50 mV per division to 50 V per division in seven steps. The limebase can be set from 50 ns fa 0.5 s per division. The maximum input voltage Is 35 V. A minus point Is that the supplied USB cable is rather short. That's a pity, because if hardly makes a dif- ference in the overall cost. As with many of the tested instruments, here we find an external trigger optian. »S©-229 USB Software and user interface Va Etc raft differs from the others in this regard. The user interface consists of three windows, which can be individually positioned an She screen. Naturally, yau can also arrange then neatly In a row or column. The advantage of all this is not immediately apparent, but it Is an amusing leature. Operation is simple and clear. With ihe manual at hand far consulta- tion, everything is quite quickly dear. Conclusion Not a rapper, cut a fun and afterdate oil af hobby gear with attractive software and a pleasant user Interface. A basic oscillo- scope without any Fuss or bother, with a somewhat limited frequency range. Gcera- iicn Is simple, so even beginners can han- dle It easily. For higher performance or semi-professional applications, the DSO- 2 100 would be a better choice. V2B05 * elsklcf dertrenin 23 TEST USB OSCILLOSCOPES HSfiii fd Bitscope is □ company that is not especially well known in Europe. Hav, r evef, it already has many years or experience in designing and selling several types of PC oscillo- scopes with o variety of interfaces. Besides versions with RS232 and USB ports, there is also a network version available w ith on Ethernet interface. That makes it easy to couple several 'scopes with each other and a PC, and it dramatically increases the data transfer rate. The products are sold exclusively by means of direct sale via the BItscope website. Bitscope B5-50 What a little jewel! It s scarcely larger than a pock of cigarettes, but its performance is not small at all. The Bitscope BS-50 is a very good instrument. Unfortunately, it has only one BNC connector. However, a wide range of signals can be input via the 26- way POD connector next to the BNC input. The BNC input also has an unusual feature. The normal input impedance is 1 MO in parallel with 20 pF. However, when you use the FFT mods the signal source is quite often a transmitter output (but with the sig- nal attenuated by a considerable number of dBs r since the input naturally can t han- dle nigh power levels). Transmitter outputs typically have an impedance of 50 Q, and the Bitscope allows the input impedance of the BNC input to be switched to 50 Q. The B5'50 has nice specifications for an oscilloscope. The analogue bandwidth is 1 00 MHz. The sampling rote can be con- figured over the range of 4-40 MS/s in fast mode. Other modes are also available [in combination with other measurement data, for example) with a moximum sam- pling rate of 20 MS/s. And then there is also a alow' mode. Various Types of signals can be connected fo the POD connector, and it also provides the function generator output (AWG), a serial I/O port, and two supply voltages, the BS-5G can be pow- ered externally, but like all USB 'scapes it is normally powered from the U5B port. Bitscope BS-310 This unit is a goad deal larger than the B5- 50, but ft has the same professional appearance. Here we find two BNC com nectars ana a 26-way POD connector. The BS-310 is distinguished tram the other Instruments by having switches on ihe front panel. They serve to switch the input imped- ance from 1 MQ to 50 Q. We already explained what that's about in the descrip- tion of the BS-50, but in that case the switching is performed via software. The specifications of the two Bitscope mod- els ore the some except for a few details. One of the differences involves the size of the memory buffer, w hich Bitscope calls the 'channel buffer depth'. In the BS-50, if is 32 K samples (15 K5 in mixed mode). For the BS-310, the value is 128 KS. Both instruments have the same bandwidth ar.d sampling rate. Software and operation This was actually not a problem with any of the USB 'scopes, and thus not with the Bitscopes. The Bitscope instruments belong to ihe small minority of instruments in our test selection with Linux support. After the software has been installed and the application has been started, the screen initially displays o Lissaious figure with \w/w bitscope .com J at the edge of the fig- ure. That's yet again something different. The user interfaces of the BS-5G and the BS- 310 are absolutely identical. Practical experience The graphic user interface comes to life when you click on ihe Power button at the upper left. The screen that appears after ibis is especially handsome. We hod to stop and admire it for a while. Although we looked long and hard for an auto-setup function, we couldn't find any. That's a pity, if the function is there, it is well hidden, bath in the manual and in the user interface. The manual is truly necessary if you want to Take full advantage of what the instrument has to offer, but the Bitscopes ore naturally noi toys. Besides various sampling modes, they also offer combined display modes. Conclusion These instruments combine high quality and performance with compact dimensions. Their specifications are nearly the same except for o few details. The choice will thus primarily be determined by questions such os whether you want to have a second BNC input. Other than that, they are splendid instru- ments and definitely suitable for professional use. The BS50 is supplied with a set of test leads that can be connected to the PCD con- nector, in addition to the USB cable (which is supplied with every instrument). The BS- 310 is supplied with o more complete set a; accessories. Besides the test leads, it comes with two probes, an AC adapter and mains cable for externa! power, and a flat cable with a POD connector. 24 clcklef dsrtrrits - 9/2005 Parafe Tnis USB oscilloscope actually cannot be compared with the rest of ibe tests d instru- ments. The Parallax is o low-budge! 'scope with dear limitations, and it is specifically marketed far educational and bobby pur- poses, Its price is also considerably Sower than that of the olher instruments and its cose is correspondingly simple. There are three connectors on the front pane! which resemble power plugs for AC adapters or chargers. It does not come with any probes, but instead has test leads with clips. The package also includes a small servo motor, a test circuit board and o few elec- tronics components (although it is also avail- able without the accessaries]. The specifications are quite basic. The sam- pling rate is 1 MS/s for single^rhanne! operation or 500 KS/s for two-chan ne! operation. The bandwidth is 200 kHz, and the resolution is B bits. Software We had a few problems at first, but that came from our cocky assumption that real technical boffins never read the manual before getting started. That was obviously a mistake, and we can only recommend that you simply read what you have to do, and then the installation will be nice and easy. However, a reproducible problem did occur during our test. If we left everything con- nected and switched off the PC, the famil- iar blue Windows XP error message screen appeared when the PC was started up □gain. The remedy was to disconnect the equipment, restart, and then reconnect it. Unfortunately, we didn't have enough time to test this on o different PC, Practical experience The graphic user interface is dear and does not generate any questions. Several tabs ai the bottom of the screen can be clicked open to make settings or make measure- ments, with or without using cursors. Here again we were unable to find an auto-seiup function. Other than that there's nothing special to report about the Parallax, it dis- plays simple signals quite nicely, and the measured signals can be exported in the form of imaces or data. u Conclusion This is quite obviously an educational instru- ment for learning how to use an oscillo- scope by direct experimentation. The spec- ifications and features ore limited, but that is compensated by the fact that this is the least expensive instrument in rhe test. Matiuf a c fairer Model Manufacturer's Internet address UK distributorfs) Bitscope BS-50U BS-3 1 OU www, bitscoDe.com Order exclusively via the Internei Conrad D5O-220U5B www.conrad.de Conrad International www.conrad.com ETC M522 wv Av.etc^k.oom Directly from manufacturer Parallax USB Oscilloscope .v,vw. parallax, com Milford Instruments wvAV.mil in steam Picaiecb Picoscape 3205 www. o s c otec h . com CPC P3c www.cDC.c6.uit Parnell Electronics Components uk.farneJJ.com IMEX wwwilmex.co.uk ^ Rapid Electronics v/ww. rap id electronics .co. uk Ka les ! e ad www. ka ! esfead . co. u k : R5 Components rswww.com RK-system PenscopsDAG ww -v. r k-s v s f e m , co m . c ! via DDS Scope Tradmq www.ascil3QSCoop.nl or Demotech Denmark www.demoteclidk Tiepie Engineering Handyscope HS3-10G Handy scope H54-50 www.tieoie.nl Tiepie UK sales office wvAv.tiepie.nl/uk/home USB Instruments Stingray DS1M12 Swordfish PS40M10 www.. u s b-i ns try m e n ts.com Easysync www.easvsvnc.co.uk 9, 2005 - elektor ehtironiES 25 TEST USB OSCILLOSCOPES Final toiclusi© s Ten common luiiste Guido Wolf - Marketing Manager, LeCroy Europe Time for a s umm ary. Testing this set of USB oscilloscopes was a very interesting project. PCs are increas- ingly being used as tools to help peo- ple do their jobs. In addition, USB oscilloscopes provide an excellent opportunity to combine certain aspects of an electronics worksta- tion, such as technical support (data- bases ), measurements, record-keep- ing, and exporting measurement reports to Word or Excel. In principle, a USB oscilloscope can be just as good as a 'real 1 one. Actually, that isn't right way to say it. A USB oscil- loscope does the same job as a tradi- tional scope, but it simply operates in a different ma nn er. The range of variation in the features and capabilities of the eleven instru- ments selected for the test is quite large. They include very simple instruments such as the Parallax, which is actually only intended to be used as a learning aid. Perhaps hob- byists who do the odd bit of putter- ing will also hod it useful, but that's just about the limit of its utility. The Stingray is also fairly basic with its limited specifications, but it is quite a bit better than the Parallax and has a much nicer design. In any case, both instruments are worth what whey cost. We were not especially satisfied with the Pens cope DAG, Its design also leaves something to be desired. The user interface is clumsy, although the specifications are quite decent. However, it wouldn't he our personal choice of instrument. The DSO-22GUSB from Conrad Elec- tronics has a good price / performance ratio. It has reasonably good specifi- cations and a very reasonable price. If you want something more, there is also the DSO-2100. The Handy scopes from TiePie are especially attractive instruments. They are available with different sampling rates for each model, with prices in proportion. We have listed the specifications and prices of the two Top -end’ units. They clearly fall ® No! taking enough time to study the capabilities, features and operation of the instrument, with the result that several functions remain unused. Read the manual! • Failure io take possible error sources in the meas- urement setup into account, or not giving sufficient consideration to such error sources, which con col- lectively generate a relatively ! arge error. • Failure to exploit the available resolution of the oscilloscope. An 8-bit measurement Is approx! moiety five times as precise as a eyeball' estimate. G Restricting measurements to visual examination of signal waveforms using the oscilloscope function without using other functions, such as histogram- ming, trend analysis or FFT t fa fully investigate the characteristics or the signal. O Undersampling the signal due to an inadequately sized memory burfer in the instrument. • Using a passive probe to make high-frequency measurements or measurements or very sensitive circuits. Q Viewing the signal over time span that is too short, with ihe result that problems and their conse- quences ore often not recognised. • Viewing too many waveforms at the same lime in i Mode! Analogue/ digital inputs Resolution Max. - ~ “ 'i • 1 • - - •' sampling rate Input range min/inax Internal memory Handyscope HS4-50 4 x BMC 12/14/16 bits (configurable) 50 MS/s I 50 mV / 20 V/div ■ 128 KB - ■ — - . - — i. Handyscope H53-1G0 2 x 8NC 12/1 4/16 bits (configurable) 1 00 MS/s 50 mV / 20 V/div 128 KB Picoscope 3205 2 x BMC 8 bits 100 MS/s 10 mV / 2 V/dlv 512 KB 1 ii Bitscope B5-31 0U 2 x BNC 2 x POO 8 bits 40 MS/ s 513 mV 10,8 V 128 KB ETC M522 2 x BNC 8 bits 50 MS/s 10 mV / 5 V/div not stated PenscopeDAQ ! 1 X BNC 8 bits 1 00 MS/s 20 mV / 25 V/div 128 KB Bitscope B5-50U 1 x BNC 2 x POD 8 bits 40 MS/s 513 mV / 10.8 V 32 KB Swordfish PS40M10 1 x BNC 10 bits 40 MS/s 100 mV / 10 V/div not stated Stingray D51MT2 1 2 x BNC 12 bits 1 MS/s 10 mV/ 5 V/div 32 KB Conrad DSO-220 USB 1 2 x BNC 8 bits 20 MS/s 50 mV / 5 V/div 32 KB Parallax USB Oscilloscope 2 x power plug 8 bits | 1 MS/s 1 00 mV / 5 V/div not stared Beta version cr mullithanne; software available on website Price without instruction manual and test material 26 dU.tar i etlrc “Its - 5 TODS res in using digitc I a single window, Thai reduces the resolution, so the signals cannot be portrayed with suffi- cient accuracy. Q Failure io exchange practical experience ■/ith other electronics technicians and engi- neers who use the same type or model of meas- urement equipment. Exchanging experience and information about setups can be very use- ful and can save time and trouble, © When purchasing an oscilloscope, buying the top-ranked mad el or the cheapest model. Care- fully examine the full range of available models and select an instrument that does what you need. in a different price class, but they are professional instruments. They might not be your first choice as a hobby- ist, but you might want to compare the price with that of a comparable conventional oscilloscope. For a demanding electronics technician or engineer, the Handy sc opes are defi- nitely worthwhile. The ETC M522 is a nice midrange model, as are the Bitscopes and the PicoScope. AJ1 three of these instru- ments offer a lot for what they cost and provide substantial performance. Based on the test results, you can decide for yourself which model meets your wishes and whether it fits within your budget. Finally, we would like to draw a bit of attention to the software that comes with the instruments, A cou- ple of the models have Linux sup- port, but none of them has Mac soft- ware. Maybe that's something the manufacturers should turn their attention to. Supplied probes n/o n/a Software 98, ME, 2000 & XP 98, ME, 2000 & XP 98 SE, ME, 2000 & XP 98, ME, 2000, XP & Linux 98 SE, ME, 2000 & XP not stated, tested usiria Xf 98, ME, 2000, XP & Linux 2000, XP & Linux 98, ME, 2000, XP & Linux 3 test leads 98 SE, ME, 2000 & XP 98, ME, 2000 &XP Power supply (extemal/vta USB) Extras USB USB USB USB/external USB USB USB/external USB USB USB USB AWG/FFT FFT AWG/FFT FFT FFT cass FFT case AWG/FFT FFT instruction manual and rest material FFT €1380 (£960] AWG/FFT €1108 (£765) £599 (€869) AC power supply with adapter AWG/FFT S495 €487 (£335) [272 (£187) AWG/FFT $295 €245 (£169) 22 1 (£152) €169 (£117) €134 (£93) (€116) (£80) 9/20Q5 - eldtl&r elatrorris 27 For rapid development of electronic systems BLOCKS E-btocfcs are small circuit beards each of which contains a bfock of efadronics typkaily found in an e.ectroiVc system. Blocks cart be programmed in C r Assembly a/vd are tigfoSy integrated with Rowcode - which hsiardiy converts flow charts info PlCmicm code. NEW mm Hi WWW. Matrix Multimedia LI m tied s aies@matri xmultifne diax o.u k L 0870 700 1831 f_ 0870 700 1832 „.and more at: training courses h PlCrnkrc{R) programming, CPLD programming and ECAD Low cost USB PIC programmars (^| st £27. modai .plus a wide range of add-on boards and accessories... plus Incredibly easy to use software based on flow charts... ...equals extremely rapid system development: like this mobile text messaging system bulrt from E-blocks, S.b?rt7L £SS) and so Hands on training courses Resources for learning CPLD programming Complete courses in electronics end programming Equipment for datalogging, control and PC scopes www.LichfieldElectronics.co.uk 1 '' T t? first advert from Lichfield Electronics, a new electronics shop will open where i come oitd browse a wide range of electronic components, equipment and imho use designed as well as 3rd Party kits. All in a city centre shop* open 7 days a week 9 till 5, * So come and pay us a visit at Lichfield Electronics, Visit our website or send us a SAE for more information. Look for our ad veil next month, Aovue Stockist In stock is a range of Aoyue Soldering equipment like the 909 ail in erne repair system pictured right which includes a 15V ftSifi temp controlled soldering Iron and a hot air soldering gun for S'N© work. Components and Kits. Just like any good electronics shop We will stocking the norma! array of TTL & CMOS loc as wait as a few more unusual items like th N uniat ran pictured right and a selection oi We will also be stocking a large range snore on these nest month JAM r ■' f Mim-Siit. I BAM - ■ liiait 3 The Coro C ' o n d u 1 1 S i re ei. 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Try the full version completely free for 30 days. www.spice-software.com Tel; 01603 872331 Research House, Norwich Road, Eastgate Norwich, NR10 4HA. Fax: 01603 879010 Email info@looking.co.uk mi 9/2(105 - ekklEJf Ebdranls 29 Flemming Jensen The two most important properties of a capacitor are its capacitance and its internal resistance (ESR). You need to know both values in order to judge whether a capacitor is suitable for a particular application. The meter described here combines two popular Elektor Electronics projects to create a convenient new instruments that rightly belongs in every well- equipped electronics lab. P^igital capacitance meters have * WDecome lairry inexpensive. Musi commercial capacitance meters have a measurement range or a few picofarads to 2,0 GO mF; Some can even go as far as 20 mF, but that's where it siops. Large capacitors with values of several hundred millifarads, which are often used In power supplies, printers and photocopiers, cannot be measured using such meters. That means you will need a different (and more advanced) type of meter. There s another important property oi a capacitor that cannot be measured using a normal capacitance meter: its equivalent series resistance (ESR). Beside the capacitance, it is one of the mosi important properties of a capaci- tor. An ideal capacitor is a purely reac- tive component, with a 90-degree phase shift between voltage and cur- rent. However, practical capacitors also have a non-zero resistance in series with the Ideal 7 capacitance (see "Figure i). Tne resistance represents the losses inside the component, and it. largely corresponds to the quality of the capacitor. Electrolytic capacitors tend to dry out after a long time, which causes their ESR to increase. A pure reactance can- not generate any hear, due to the phase shift of exactly 90 degrees between voltage and current, but a resistance can generate heat. Tne heat 30 ddiior elscifc-nscs - 5/2005 dissipated in a capacitor due to its ESR increases in a switch-mode circuit, which causes its quality to deteriorate even more. With an aged electrolytic capacitor, it is not uncommon to find that although the capacitance has decreased by only a lew percent, the ESR is more than 100 Cl. An ESR of this magnitude makes a capacitor com- pleteiy unusable in switch-mode cir- cuits and hardly usable for any other type of application. Why a combined meter? An ESR meter and a capacitance merer measure two different things. They complement each other. That's why it's convenient to combine the two meas- urements in a single instrument. For this purpose, the author has merged the especially popular ESR Tester pub- lished in the September 2002 issue with the Autoranging Capacitance Meter published in February 2003 (and also designed by the author). The result is a handy instrument with a dual function and outstanding charac- teristics. Toe new instrument also lias a consid- er ably more up-to-date design than the original versions. The design of the original ESR meter was based on a voltmeter IC, bur new design is built around a type 16F877 PIC microcon- troller. The advantage of this is that some new features can be added, while there is also enough room for the program for the capacitance meter. The following capabilities have been added to the ESR meter - AC resistance (ESR) and DC resist- ance are displayed simultaneously In the old design, you had to select one or the other by pressing a switch. The DC resistance indicates whether the capacitor is internally shorted (and thus simply kaput 1 ). - The new design asks the user to short the probes together when the meter is switched on, so the offset can be measured. With the old design, this had io be handled mechanically. - An audio function is built in to avoid having io always keep an eye on the meter. Thai's primarily helpful when you're making measurements on capacitors deep inside a device. The rounded -off ESR value is indicated by beeos. If the measured ESR is in the ■ range of 3, 1-4.1 Q r for instance, four beeps are emitted. Tne meter also gen- erates a warning signal if the DC resistance is less than 10 Q. No beeps are emitted if the measured ESR is greater than 10 Q, since a capacitor with such a high ESR value probably should be replaced. If no signal is emit- ted, you should briefly check the dis- play to see what's wrong. No new functions have been added to the capacitance meter. Here the major change consists of rewriting the code for the PIC16F877. Measurement principle of the capacitance meter The complete schematic diagram is shown in Figure 2, The circuit of the capacitance merer is based on a CMOS version of the well-known 555 timer IC, which is used here as a monostable multivibrator. The PIC provides the reset signal, controls the trigger input, and monitors the output of the 555, The larger the value of the capacitor to be measured, the longer the output of the 555 remains high. A counter in the PIC counts up as long as the output remains high. The count is read when the output goes low. The PIC automatically switches between the various measurement ranges. The meter has three ranges: 1-9999 pF, 10-9999 oK and >10 uE To make the measurement easy to read, a value of 1000 pF or 1000 nF is shown as 1,00 nF or 1.00 liF respectively. The capacitance meter has automatic zero adjustment. After the instrument is switched on, the PIC executes a rou- tine to measure the residual capaci- tance of the probe leads or other exter- nal circuitry. The measured value is subsequently subtracted from every reading to yield the correct value, so ihe offset resulting from using different probe leads does not affect the read- ing. It's thus important to ensure that the meter is not connected to a capac- itor when if is switched on. although this actually only applies to the pico- farad range. For capacitance measurements in the other ranges, no problem will result if the capacitor is already connected before the meter is switched on. Imme- diately after the automatic zero adjust- ment, the meter stairs measuring in the picofarad range. If the capacitance is too large, a counter overflow occurs and the PIC selects the nanofarad range. A lower charging resistance is selected for this range (R17-R19 and P2-P4), so the charging current is higher. If the capacitance is still too large, the PIC switches to the micro- farad range and completes the meas- urement in, that range, regardless of the charging time. The results are dis- played on a two-line alphanumeric LCD module. Hum interference The input impedance is very high in the picofarad range. In that range, the capacitor is charged via a resistance of 5—6 MO. As a result, die meter is quite sensitive to AC mains interference (hum) in the picofarad range. You should keep the meter well away from transformers and similar components when making measurements in the picofarad range, since otherwise the displayed value may fluctuate. In order to suppress the effects of pos- sible hum, the measurement is made twice in the picofarad range at an interval of 10 ms. Tne average value of the two measurements is calculated and displayed. That makes the meas- ured value more stable. The imped- ance is relatively low in the two other ranges, so no special measures are taken. The measurements on those ranges are thus single measurements without any averaging. Large capacitances Capacitors with values less than 10 mF are continuously measured. The measurement cycle is repeated period- ic ally starting with the picofarad range, followed by the nanofarad range and then the microfarad range. Capacitors with values greater than Ideal capacitor OHU- i J reactive part Xc = ESR J 2-f-C 015022 - 11 Figure L The most important property of a capacitor is its capacitance. The second most important properly is its equivalent series resistance (ESR). 9/ 20b - elektoi ekdrcnrt* 31 HANDS-ON TEST & MEASUREMENT Figure 2, The complete schematic diagram of the tapadfarue/ESR meter. 10 mF (milli-farad) are not measured continuously. Instead, a series of four measurements are made and the results are then averaged. This method ensures that the capaci- tor is fully discharged and charged and generates highly reliable measure- ments. It also limits the current con- sumption. The instrument must be switched off and then on again in order to make a new measurement. Contin- uous measurements are made in all other ranges. Measurement principle of the ESR meter A 100- kHz square-wave signal that supplies a constant current is applied to the capacitor being tested (the ‘capacitor under test' or G.u.T), The value of the ESR can be determined by measuring the AC voltage across the capacitor. If the capacitance is suffi- ciently high relative to the frequency the voltage drop due to the reactive impedance is negligible, so the voltage across the capacitor is entirely caused by the ESR. This voltage is rectified and fed to the voltmeter. The operating principle is illustrated in Figure 3. Here it is assumed that the C.u.T. is rated at 100 uF and has an ESR of 10 Q, The reactive impedance (X c ) is equal to Q,5tl/U or approxi- mately 0.0159 Q, which is negligible relative to the ESR value of 10 Q. The voltage measured across the C.u.T. is thus the voltage across the ESR. As the two electronic switches are actuated synchronously at the same frequency, a constant differential voltage is pres- ent at the input to the opamp. The op amp passes the differential voltage (in this case 11 mV) to its output, so the voltage at the output of the opamp is proportional to the ESR value. Figure 4 shows a different example, with a test capacitor rated at 0,1 uF and having an ESR of zero ohms. As already noted, a fairly high frequency is used to keep the effect of the reactive impedance as small as possible so that even small electrolytic capacitors with values as low as around 0. i uF can be measured. That makes if necessary to further reduce the effect of the initial 32 cictft cries ■ 9/20Q5 Figure 3, With q capacitor rated at 1G0 pF end having an ESR of 1 0 Q, the reactive impedance is negligible and the ESR (which is purely resislive) determines the output voltage of the opamp. figure 4, The situation with a capacitor rated at 0-1 pF and having an ESR of 0 Q. Here the average output voltage of the apamp is 0 V, integration of the voltage waveform. Here the ESR is zero and the reactive impedance is 0.5nrC\ or approximately 16 £2. As can be seen, the differential configuration of the opamp causes the sawtooth integration waveform on the inputs to be summed to yield a saw- tooth voltage on the output with an average value of 0 V The resulting volt- age after integration by the subse- quent RC network is 0 V. and this value is applied to the input of the voltmeter. If the capacitor had an ESR of 10 Q, the sawtooth voltage on the output would still have the same form, but it would be superimposed on a DC component due to the ESR. After the sawtooth was filtered out by integration, the remaining voltage would correspond to the actual ESR value of 10 Q r while the effect of the reactive impedance of 16 Q would have been eliminated. Multiple PICs The frequency generator in the circuit of the original design has been replaced by a PiC (type 16E84). The 16F877 cannot be used for this purpose because the signal cannot be inter- rupted unless a DC tests is being made. The 16F34 uses the same clock oscillator as the 16FS77. The advan- tage of using a second PIC is that it makes it unnecessary to align the 100- kHz generator frequency. It also allows the generator to be easily switched between AC and DC measurements. These modes are controlled by the 16F377, which uses interrupt routines to determine what the 16F84 has to do. Component selection As this circuit works with high fre- quencies and signal levels in the milli- volt range, a differential amplifier with a low offset and large bandwidth must be used. The LF412 meets these requirements and is also not all that expensive. The HC version of the well-known 4066 quad electronic switch IC provides fast switching times, which reduces the effect of the undesirable reactance by a factor of 2. The best results will be obtained if the 9, 2<3Q5 - j’rktGF dtflrcdo 33 HANDS-ON TEST & MEASUREMENT COMPONENTS LIST Resistors: R1-R4 = 56Q R5 R8 R24 - 2kfl2 R9,RiO,Rl 5,R1 6,R25 R26.R28,R29 = 1 Gk£2 R1 1-R14 = 1MD \% R1 7 - 8MQ2 R 1 8 = 7kQ85 R19 = 1200 R20,R21 = IkQ R22 = 82kl> R23 = 47Q R27 = 2200 R30 - 1 800 l - = 1 OOkQ 10-turn preset P2 = 1 MO 1 0-turn preset P3 = 1 kl 2 1 O-turn preset P4 = 2000 1 Q-turn preset P 5 = 25kO preset P6 = lOOkO T O-lurn preset Capacitors: Cl = Inf C2 = 47nF C3 = 22pF C4 = 27pF C5 = IOjjF ! 6V radio! C6 - 220nF C7.C8.C9, Cl 2-C17 = jOOnP, lead pitch 5mm C10.cn - 1 OjjF 16V radial S emi co n d u c tor s : D1 = zener diode 5V6 500mVV D2-D5 = 1 N4007 I C 1 = PJ C \ 6 F 8 77 -20/ P, p rc-g ra m tried , Publishers order cede 040259* 41 * IC2 = PIC16FB4A-20/P, programmed Publishers order cade 040259-42" 1C 3 - 74HC4066 EC4 = 107660 EC5 = TIC555 IC6 = 78L05 IC7 = LF412CP T1 = BC557 Miscellaneous: Bzi = AC (passive) piezo buzzer 51 - switch, 2 changeover contacts 52 = switch, I make contact Kl = LCD module 2x16 characters (e g. Qigikey # 153-1078-ND) XI = 2GMHz quartz crystal 2 wander sockets for banana plug Measurement cable Enclosure, e.g., 5ERPAC H75 (Digikey # 5RH75-9VB4SD) FCB. Publishers order code 040259-1* Disk, source- and hex-cade Files. Publishers order cade 040259- 11 * or Free Download " see Elektcr SHOP page or www, elektor-electromc3.CQ.uk Figure 5, Dauhla-sided circuit board layout and component layout for Ihe ESR/copacitance meter* 34 Mfcr rkdro^ci - 9/2005 Keep smiling Even if we run into major problems in our lab we always try to see the positive side of things — if only to con- vince ourselves that a troublefree life would be boring. Engineering Flemming Jensen's ESR/C Meter from blue- print right up to publica- tion in print was a far from smooth process and with hindsight we have to admit having made an error or two when assembling the proto- type. Nothing too seri- ous of course, but still... Karel Wa I raven T n ,e first lire siqn= of ihe circuit were hopeful. The display produced le g- ible lexis, so at least the micro- processor is running its program. Then came the problems. Measur- ing capacitors v/as troublesome If not impossible — usually, the dis- play remained stuck at one firm r 0' and that's no incentive to build an ESR/C Meter. So we fop the usual checks on the board. Always start by measuring the supply voltage directly on the 1C pins — both the +5 V and ground roils should be Inspected. Next up is the micro- processor clack end bingo there we gat 6.66 MHz instead of the desired 20 MHz - the auarrz crys- tal was cheer fu y resonating at its fundamental frequency msfeca of tr e third o-.erfone. Sometimes this is a false reading however, the 50-pF scope probe capacitance wreaking havoc at she oscillator input. How- ever a rock solid 6.66 MHz was measured of ihe oscillator ou/puf and we were using a 1:10 probe so exlra capacitive loading would be small. This leaves several olher fault factors to be considered: the PIC may have been programmed for ‘standard crystal" instead of ‘high s reed crystal or the two xial loading capacitors may be too large. Also, the crystal itself may be at fault, some will simply refuse to switch to overtone resonance, fn our case. It turned out that the PIC was incorrectly programmed and the problem was salved quickly. Alas... the display now greeted us with total gobbledygook. Strange, but sill l reassuring to know at this paint that mere were no display wiring errors — after all, ihe display had worked just : Ine we corrected the clack frequency. A liming error? 1C displays may not be driven too fast. For example, ihe datasheet tells js to observe a minimum length of 450 ns for the enable pulse. Inter- nally, a PIC operates at the xrai fre- quency divided by four so In the- ory, at 20 MHz, it Is abb to supply new data on Its I/O pins every 200 ns. That looked like a plausible explanation of the phenomenon we were faced wi th. fh is kind of error easily creeps into a design. The test circuit runs tine at a lower clock speed, hooray, ihe design is quick v optimised while drawing the schematic and then... a final check of ihe pulse timing is forgot- ten. However, it could also be on undiscovered error — some LCDs have no problems with 200-ns pulses, while others from o different series or manufacturer wllj hong. We cast a critical eye on the LCD driver routine, created □ longer enable pulse and reprogrammed the PIC. The LCD then worked os desired. By itself, that is,, because otter all this hard work, the readout was still meaningless. We quickly found out that she measured values were Invariably negative instead of positive, one the microprocessor pro grams was known la turn any negative value Into o solid zero. In theory, ihis con happen if the phase of the synchronous detector has been swapped over. A her a lot □1 searching and debating, we agreed fher that was not ire case. Wild theories were heard then in the lab, until it transpired then ihe switch selecting between capaci- tance and FSR measurement was incorrectly wired causing a mighty offset In the detector. Nobody hod thought of such q simple exchange of two wires! The moral of the story: always check obvious matters first. Do not fear the worst and certainly do not dig deeper than necessary! 9/2005 - dsVtvT slstlrorks 35 HANDS-ON TEST & MEASUREMENT recommended components are nsed. However, the performance is still acceptable with a normal 4066. Compact construction Thanks to the use of two mi croc on* traders, the size of the overall circuit remains relatively small, so the printed circuit board designed for the circuit (Figure 5) has quite modest dimen- sions. There are only a few components that have to be connected to the circuit board via short leads. The LCD module is connected to Kl. Switch SI, which is used to select either capacitance or ESR measuring mode, is wired to con- nector SI on the circuit board using six short leads. Points CT and C- are con- nected to two measurement: terminals or sockets located on the front side of the enclosure. The pins marked. Sig- nal—, Signal- Sense- and Sense- are for connecting the additional ESR test leads with their separate sense lines in order to measure capacitors while they are still connected in a circuit (see Fig- ure 6). The batten/ and power switch S2 (BT1 and S2, respectively) must also be con- nected to the circuit board, as well as the beeper (BZ1), Test probes Four-wire measurement is used here to compensate for the voltage drop in the test leads. Each of the test leads has two screened conductors, consisting of a signal lead and a sense lead (see Figure 6). This prevents the measure- ment from being corrupted by hum, noise or ESD interference and allows a stable zero calibration to be imple- mented. Calibrating the ESR meter The offset is set to 40 mV instead of 0 V because the ADC cannot handle negative voltages. Short the test probes together and connect a volt- meter to pin 7 of the LF412 (IC7). Then adjust PI for an offset voltage of 40 mV The resulting offset can then be com- pensated by the software. However, that requires shorting the probes together when the meter is switched on in the ESR mode. The offset voltage is converted by the ADC. The resulting value is stored in an E E PROM and sub- tracted from the measured ESR value when a measurement is made. Switch the meter to the ESR mode and switch on the power. You can use P5 to adjust the contrast of the LCD module. Short the probes together when you are requested to do so. Now connect the probes to a 10-Q resistor and adjust ?6 until the display shows a value of 10 Li. Connect the meter to several working capacitors La turn, without and without a 10-0 resistor in series, to verify that the meter is work- ing properly. Calibrating the capacitance meter You need a pair of precision capacitors to calibrate the capacitance meter, A value of 470 pF / IT is suitable for the picofarad range, and a value of 220 nF ! 1% can be used for the nano- farad range. Both values can be obtained at a reasonable price from various vendors, such as FarnelL Do not use values of 1000 pF or 1000 nF, since that can cause the display to flicker between 999 pF and 1.00 nF or 999 nF and 1.00 uR respectively. The easiest way to adjust the range above 10 uF is to use a commercial capaci- tance meter. An alternative method is to use the formula t = RC and a simple stopwatch. Keep the meter away from trails form- ers and strong 50- (GO-) Hz fields. Switch on the meter, connect it to the 470 -pF capacitor, and use P2 to adjust the value on the display to match the value of the capacitor. Next, connect the meter to the 220-nF capacitor and use P3 to adjust it to the right value. Finally, you can use P4 to set the right value for youi reference electrolytic capacitor. After that the meter is ready for use. From now own, no capacitor new, old or NOS (new old stock) will hold any secrets for you. Things to pay attention to Always discharge the capacitor before connecting the meter to it* Switch on the meter before connecting it to the capacitor to be measured. Four measurements are made on capacitors with values greater than 10 mF, After that, the meter displays 'Ready', and it must be switched off and back on to make a new measurement* Be patient when measuring capacitors with very large values* It takes approxi- mately !0 minutes to measure a 370-mF capacitor. Warning Although ihe inputs of the meter are pro- tected by diodes, if Is good Idea to dis- charge large capacitors before measuring them. The risk of burning aut the protec- tion diodes is particularly high with fit' ter/huffer capacitors used In power sup- ply circuits. Figure 6. 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If an RS232 interface is essential, for example when programming microcontrollers, there are commercial adaptors available to bridge the gap between RS232 and USB. However, things do not always go as smoothly as one might like... The RS232 serial interface will continue !o live on for as long as I he re are peripherals that use ihe interface. Adaptor manufacturers recognise this, and so there is a range of U5B’to-RS232 interface converters available for notebook, laptop and desktop computers that are not fitted with an RS232 interface. Experience wilh these adaptors shows that the conversion between USB and R5232 aoes noi always proceed os smoothly as one mignt wish. We hove taken a closer look at two adaptors and tried ro determine where the problems lie and who! con be done to overcome them. As example practical applications for a U5B-k>RS232 adaptor we have taken the 89S8252 Flash Microcontroller Board [E/ekfor Electronics December 2001), the DRM Receiver [March 2004] and tne Serially Programmable Crystal Oscillator (March 2005). A Further product of our research is a handy PC program to test both real and virtual RS232 interfaces. The program is available for free down- load from the Eleklor Electronics website. Manhattan The Taiwanese manufacturer Manhattan produces an adaptor in the form of a short cable (Figure 1). At one end is a USB plug and at the other is a nin^pin sut>D con- nector. The sub-D connector housing is a moulding which contains the adaptor electronics. When first connected ro the USB port of a PC the Windows Device Manager recog- nises a new USB device and searches for o driver The nec- essary driver is provided on the CD ihat accompanies tne product; the new USB device has me nome Prolific USB-io Serial Bridge'. Windows warns that the 'Windows Logo Test' has not been passed, but this can be ignored: it sim- ply means that the device has not been tested for compath bility with Microsoft Windows XP. The new viriua! COM port will appear in the device manager under 'Ports, and a free COM port number Is allocated to if. If the allocated COM port number is greater inan COM4 [for example. 38 chktor tledreniK -9/ZG05 Figure 1, The adaptor made by ihe Taiwanese company Manhattan. The elec- tronics are built in to the sub-D connector. Figure 2, 'Advanced settings' far the new COM port in Windows XP. Figure 3. The Koller adapt o r x designed far mounting on q DIN rail, uses the FTDI FT8U232AM. COM 6) the setting may need to be changed manually. This is advisable, since many programs can only work with porls COM1 to COM4. To change the COM port number, dick on the new interface under Ports' in the Device Man- ager, so that the properties window appears. Under 'Port Settings select Advanced (Figure 2]. Here a new COM port number con be chosen lor the device, and the charac- teristics oh the FIFO buffer can also be modified. Some- times problems communicating with external devices con be solved by disabling the FIFO buffer. Kofter Tne USB k>R5232 adaptor from Kolter Electronic (Figure 3) is designed for mounting on a DIN roil for use in switching cabinets or fuse boxes. A feature of this module is thai the USB and RS232 Interfaces are galvani- cally isolated from each other using an internal optocou- pier. Eight LEDs are visible tram the outside, which show the stote of the unit and the levels on the RS232 signal lines. The adaptor uses the FTDI FT8U232AM: the^driver for this aevice is available from the manufacturer. In the Windows Device Manager the adaptor appears as 'USB Serial Port'. As before, the COM port number should be between COM! and COM4. If Windows chooses a higher number when the adaptor is installed, the port number can be changed using the same procedure as for the Manhattan adaptor. Test program The program called 'RS232 terminal' (filename: termi- nal. exe) was originally written to carry out simple tests on devices connected to a serial port. For our examination of USB-fo-R$232 adaptors it was extended to include two functions for measuring communication speed. The pn> 9, 2005 - ehxla dedfonia 39 INTERFACING K 5 V 37 reiminal COM [z 3 a«. 3 |3&iX' -j P«J v [V _ ~ BKt |i 3 5^2 p p _£) a p: *i 5r!Evi: Rnffrtg^tf fp^3 'f.: Figure 4, Tb'RS232 Tennimsl' test program shown immediately alter bunch. L COUfecOT Cb» | I r dtr r rts r t,o r cts r dsr p pj r cco DtP ; ps« T J tnJ Iztti T t:t | Figure 5. The receive window of ihe lest program shows d-3 1 □ read from a multi- meler. COM d is it n 45 5345535011 a m%7 33 if Ev if S3 56K 32 36 u 8 13 |\TC ffl 8732439046535= 43 3 61 32 32 13 y IT — 58 07 8 *350 40 51 55X V 8 im r 5167121= lUt- m £7 32435045* 3 SS S3 32 0683m .ms: 8 ssizim F d S”? i* _rl Ss-cTu-r - e : : ■ ; •- ■- r z} : SS55M dcnmv DC 1 Z 5 SIV oc tun v eei2&av 3 £l£ 5 S 2 v p dtr r rts r txo r crs r osr r p- r dco P7n U-^ | Tt4 gram can be downloaded for free from the Elehor Elec- tronics website at http:/ / YAVW.elektor-electranicsxo.uk. File number: 050071"! "Lzip. The window which appears when the program is started is shown in Fig ure 4. When the COM part allocated to the U$B-toR5232 adaptor is opened o check is made to see if the R! (ring indicator) signal is active. In both of the USB-io-RS232 adaptors tested here ihe RS232 input is internally wired in such a way that the Rl signal is always active, !i is far Inis reason that there is no indicator LED for the Rl signal on the Kolter adaptor In the terminal program window the lXD f DTR and RTS output signals can be activated and deactivated at will. When it is connected to a PC the LEDs on the Koher adaptor give a visual indication of the state of the sig- nals and a voltmeter can also be used to examine the voltage changes on the interface pins. Simple U5B-to-RS232 adaptors like the Manhattan cable often generate the RS232 output signals with reduced voltages to represent the logic levels: the voltages are around -f-6 V and -6 V. in contrast the Kolter adaptor produces ihe standard output voltages of +1 2 V ana -12 V, which are the signal levels expected from a proper serial interface. Conformance to the RS232 stan- dard voltage levels can be important, for example when connecting devices to the interface that do not have their own power supply, but which steal power instead from ihe interface itself. The galvanic isolation offered by the Kolter adaptor is particularly useful in harsh industrial environments. It helps to reduce the impact of interference by effectively decoupling the driver stages from the control electronics. Start-stop Once the USB4 oRS 232 adaptor is Installed, the PC or lap- top effectively sports an extra virtual COM port. However, this part can behave in ways rather different from a real RS232 interface. The difficulty can be due to the reduced signal voltage levels on the outputs, or, more problemati- cally, It can often be due to a difference in timing Further- more, older programs, far example those from the DOS era . will of course not work ifi'ney directly access registers that control the R5232 port. On the other hand, all Win- dows programs that indirectly access the port using the Windows API will, at least in theory be able to use a vir- tual COM port without problems. In all cases it Is possible that, despite the considerably higher data transfer rate pos- sible over the USB Interface, communication is slower than usual. Examples showing hosv to pregram the Interface correctly can be found in part 3 of 'Delphi for Electronic Engineers' (E/ektor Efedrom'cs March 2005). The often considerably slower data transfer rate of □ vir- tual RS232 interface connected via USB compared to a 'genuine' R.5232 interface deserves some explanation. Since USB is considerably faster than RS232, if should be possible to emulate an R5232 interface running ai a speed of say 1 15,200 bit/s without difficulty: by com- parison, even low-speed USB devices like keyboards and mice can operate at rates of 1 .5 Mbit/ s. On the USB side, the U$B-tc>-R5232 adaptors from Manhattan and from Kolter both operate in USB version 1 .1 full speed mode, with a data transfer rate of 12 Mbit/s. One would think ihaf this would be mare than enough to emulate the fastest RS232 port, but unfortunately there is a snag. Ser- ial data is transferred over USB in data packets. The data packets are sent out at one millisecond intervals. The receiver must check that a complete and correct data packet has been received and send back acknowledge- ment data. The shortest possible turn around time for sending a single byte over USB is three milliseconds. As long as the data packets are sufficiently long, continuous communication at a speed of 9600 bit/s Is feasible over the virtual R5232 port. This in any case presupposes that large amounts of data are to be transmitted, for example for driving a printer or modem. The RS2 j 2 terminal test program shows the maximum communication speed of a connected U5B-k>R$232 adaptor when the 'Text Speea Test' button is clicked on. The TXD and RXD signals on the RS232 side must be connected together before this test is run. The program sends sixty characters of text to the adaptor, and they are almost immediately returned via the looped-back TXD and RXD connections. Comparing the speeds of virtual and real RS232 ports shows that the U5B-to-RS232 adaptor can guarantee to match ihe speed of the real port up to about 9600 bit/s. At higher com- munication speeds it starts to fall behind, since each byre must be sent individually on the one millisecond time- base. The transfer in this cose will thus take exactly 60 ms for the 60 bytes. 40 elector dctliG‘it5 ■ 9/2005 replacement PICee Development System Reinhardt Weber The 'PICee Developmenl System' published in February 2002 will not work with newer laptops not fitted with an RS232 interface. The author has developed an alternative, which con- sists of a simple adapter cable to allow the PKee system to be connected to the parallel port (printer interface]. The adap- tor coble has the advantage that it is inexpensive and DIY con- struction is possible. The figure shows how the adaptor cable is wired. The adaptor cable is designed to be used with the [CPROG programming teal {filename: kprog.exe). Under Windows XP the driver icprog.sys must be installed, located in the same directory as the program itself. The necessary steps to achieve this are shown in the following figures. Simply changing the compatibility mode in which the program runs is not enough! i [ K | " :: ! ’Tflf j ( ] 4 j sorter* I I G - r * ! r ~= ?.f 0— I* f* ' s'??! -v'i- .** T ' 1 The behaviour described above was observed under Windows XP for both the adaptors tested. In comparison, a genuine R5232 interface running at 1 15200 bit/s will transfer 60 bytes in approximately 5 ms; the USB-to- RS232 adaptor takes twelve times as long! Things take even longer when relatively small quantities of data need to be transferred back and forth alternately For example, in a microcontroller system a series of command bytes may need to be transmitted and the microcontroller may need to reply to each byte received: the USB proto- col will now bring the system grinding practically to a holt. Irrespective of the direction of transfer each byte will take three milliseconds to send and hence the effective data transfer rate will be just 167 bytes per second. This example also shows that the data transfer rare will increase if it is not sent one byte at a time, but rather in groups of bytes. Digital multimeters that have a serial port often behave like this. As an experiment, we connected a Mefex model M-4650CR multimeter to a USB-to-R5232 adaptor. For this model it is necessary to set the PC's serial interface to 1 200 bit/s and 7 data bits in the termi- nal program. DTR must also be set active as this provides the multimeter's Interface with power The test program allows any desired character to be sent to the multimeter. The reply is a text string 14 characters long which con- tains the value currently displayed on the meter If the meter is connected to a real RS232 interface the data transfer is fairly slow as the data rate is only 1 200 bit/s. If o USB-to-R5232 adaptor is used instead, there is no Fur- ther loss in speed, and in this case the adaptor properly emulates a real serial interface. Figure 5 shows the ter- minal program displaying data read out of the multimeter Similar results ware obtained From experiments with an MCS52 BASIC microcontroller system based on the 8958252 Flash Microcontroller Board (published in December 2001 with the mlcracontro ler s serial inter- race being set to 9600 bit/s. The data transfer rate was measured in bath directions. Measurements were carried out using a real serial interface and using a virtual one, via a U5B-fo-RS232 adaptor emulating a serial port. No difference in data transfer performance was observed. Control signals Controlling the handshake signals DIR and RTS as well as entering and leaving the 'break condition on the TXD line is generally slower than transferring serial data on a vir- tual R5232 Interface, since each action takes ot least the 5/2005 - elector ^Ironies 41 ilMBM INTERFACING figure 6, Tuning the ORM re reiver. I tek to r Pi m-;f ammabt^ ( lock .1 at ypfoadRAN | C COM! 0 COM, 2 r dqm2; < COM! j J„VZ "It" ID 3 ■ 21 iwh. 1427,5 kHz 4MHt Figure 7, Setting the frequency of the programmable cryslat oscillator. 1 4 VH* [ 2_,6 ilHz j 4 .ltMHi *0 -IQ'.'-: j lOu ’AH 2 J isitoEEPflOV | ttt's&AK bosic three millisecond period. The same goes for reading the state of the CTS and DTR signals. You can confirm this using the terminal program by clicking on the 'DTR speed test' button. The terminal program switches the DTR signal on and off 1000 times or the highest possible speed. Run- ning this test using a real R5232 interface under Win- dows XP results in a measured frequency of 40 kHz on the DTR line, with 1000 cycles completing in 25 millisec- onds. Using a U5B-to-R5232 adaptor providing an emu- lated interface the same process takes 6000 milliseconds, corresponding to a signal frequency of 167 Hz. This test also shows that the various versions of Windows behave differently. Under Windows 98 and Windows ME signal transitions are lost when they follow in succes- sion too quickly, whereas under Windows XP this prob- lem no longer occurs: instead, when the command to switch a handshake signal is issued program execution is suspended until the signal actually changes state. It is no longer necessary to take steps in software to ensure that the DTR signal is correctly set; but unfortunately the pro- gram runs slighity slower under Windows XP. gramming the flash memory of the microcontroller aver its SPI interface. This is achieved by the PC taking direct control of the RTS [clock}, TXD (data) and DTR (reset) sig- nals. If the board is connected to a real RS232 interface, programming over the SPI interface is a quick operation. Connect to the PC using a USB-fo-R5232 adaptor, how- ever, and the same process rakes considerably longer. The programs 'MicraFbsh and TASMEdrf were devel- oped for use alongside the 'Microcontroller Basics Course' published in E/efctor Electronics between January and September 2002 to allow data to be downloaded into the microcontroller. Since then, a software update has been necessary since timing problems have been encountered when using the board under Windows XP connected via a real RS232 interface. The new versions of the programs work without problems under Windows XP r even when the board is connected to the PC via a vir- tual R5232 serial interface. The same comments apply to the Atmeiisp program by Ulrich Banged. In any case, when using a U5B-to-R5232 adaptor communication speed is very slow, at only around four bytes per second. At this speed downloading small assembler programs is reasonable, but downloading longer programs will demand a lot of patience. Downloading MC S-5 2 BASIC [8 kBytes) will take about half an hour, although if you wish to continue to use MCS-52 BASIC you will only have to download it once. In summary, if the RTS, DTR and TXD signals must be switched by hand, She communication speed achievable with a virtual RS232 serial port is not really acceptable, although a USB-!oRS232 adaptor can be a useful stop- gap solution In an emergency. It would be desirable to be able fo reprogram the firmware in the USB microcontroller lo accept a byte and process it as eight individual bits. DRM Receiver The DRM Receiver is a project which was published in March 2004. First the goad news: ihe DRM receiver can be tuned directly using the DREAM' program under Win- dows XP using □ U3B-toRS232 adaptor [see Figure 6). The DOS oscillator in the receiver is clocked serially, with TXD in this case being the clock signal and RTS the data signal. On the oscilloscope we can see that the clock pulses occur at 9 ms Intervals tar a clock rate of 1 10 Hz. Three state chonges are required: first set the RTS data signal appropriately, activate TXD and finally deactivate TXD. During tuning several bytes are transmitted, and the process lasts about a second. Since this delay only occurs when switchina between DRM stations It causes hardly any inconvenience. However, tuning randomly in AM mode Is rather more tiresome. In comparison using a real RS232 Interlace the software manages a dock fre- quency of 10 kHz and a tuning adjustment can be car- ried out In about 14 ms. 89S8252 Flash Microcontroller Board The 89S8252 Flash Microcontroller Board we published in December 2001 has two RS232 interfaces. The first RS232 interface is intended to be used for communicat- ing with the outside world during normal operation. If, For example, MCS-52 BASIC is loaded, it provides the interface between the interpreter and a PC running a ter- mirsat emulator program. As we have already discussed, communication with a PC via a U5B-toR5232 adaptor at a speed of 9600 bit/s does not cause any problems. The second serial Interface on the board is used for pro- The original tuning programs, written in Visual BASIC and Delphi, work equally well with a USB-to-RS232 adaptor emulating a serial port, although they run some- what slower. The AM/SSB program available an the EIEX5 server can be configured to use any port from COMl to COM6. The COM1 to COM6 options 'via USB/RS232 cause extra delay instructions to be added to ensure correct operation of the program under Win- dows 98 and Windows ME. Under Windows XP the nor- mal (real) COM port buttons can be used. The program Figs also been extended to include a search function, 42 ilsItl&rdatro'iis-S’-'lOiJS which can only be used in conjunction with a real RS232 interface. Fine tuning, in steps of 100 Hz or 10 Hz (espe- cially useful for SSB operation) is also □ tedious process when using □ USB-toR5232 adaptor. The U5B-fr>R$232 adaptors from Manhattan and Kotter behove differently when used with the DRM receiver. The explanation lies in the galvanic isolation between the USB and R5232 sides of the Kolier adaptor. One might think that the galvanic isolation would improve the qual- ity of reception, as it would help to keep interference from the PC away from the receiver. Unfortunately, how- ever, the isolaied DC-ltxDC converter in the Kalter adap- tor generates interference on the ground connection at frequencies up to 10 MHz. The Manhattan adaptor is thus better suited to use with the DRM receiver. Serially Programmable Crystal Oscillator The Serially Programmable Crystal Oscillator module published in March 2005, is configured over an I^C bus implemented using the signals of an R5232 interface. For direct connection to a PCs USB port, the starter kits from Cypress [the so-called candy boards') are a possibility, since they are already equipped with their own USB interface. Alternatively, the module published in Eiektor Electronics will work, taking the roundabout route via the RS232 interface. A simple program has been written to allow the frequency fo be set easily (Figure 7). The soft- ware works without problems under Windows XP when the module is connected to the PC via a U5B-to-RS232 adaptor. Downloading the basic settings, which occupy 256 bytes, takes about 30 seconds. This procedure is only required once, when initialising the unit. When changing the frequency using the above program only a few bytes are transferred, the process taking approxi- mately half a second. Compared to the time it takes for a custom-cut quartz crystal to be ordered and delivered, this is phenomenally quick! QS"07i-i I I 1 i I i 1 I 1 1 i i I 1 I I I i* Internet addresses Kolter Electronic: wv-w.cc o r ; ; ni, (in German only) FTDI: Manhattan: wv, ,v. mcmhc ba up c e r t , c c m . Source for USB-to-seriaJ adaptors: y.-ww, o W. c d=j ‘-b - j s... d e (in German only) AM/S SB software for the DRM receiver: AW wg e, ; dms.vn: (in German only) Download software update for the 8958252 Flash Microcontroller Board: wvav b4.oinva.de. basismiraq.htm (in German only] 1 E I I t i I i i i I I i ! i i I I j A2ir r : ?-• t l PicoScope 3000 Series PC Oscilloscopes?- The PicoScope 3000 series oscilloscopes are the latest offerings from the market leader in PC oscilloscopes combining high band widths with targe buffer memories. Using the latest advances in electronics, the oscilloscopes connect ta the USB port af any modern PC making foil use of the PCs' processing capabilities, large screens and familiar graphical user interfaces. High pf’rformuiinL’: 10GS s sampling rate & 20DMH/ hand width 1MB buffer memory High spued USB 2,0 interface Advanced display & trigger modes Compact & portable Supplied with PicoScope S, PrcoLog software Tel: 01480 396395 www.picotech.com/scope286 Tei h tu tt< fgx l.imth'd 9= dertforfio — - 43 Gunter Koch Lengths and distances are usuall measured using a yardstick or measuring tape. For inaccessible locations, and especially for measuring the level of a liquid in a container, using) an ultrasonic device to measure distance is an attractive alternative. _ _ _ _ n 1 .n, i tv 1 * *■ Ultrasonic distance measurement involves using pulses of ultrasonic energy that are emitted by a transmit- ter and sensed by a receiver. The time required for the acoustic pulse to travel from the transmitter to the receiver is proportional to the distance, and this time can easily be converted into dis- tance. In addition to making direct’ measurements of the distance between the transmitter and the receiver, this technique can also be used to make a 'indirect ‘ measure- ments using the reflection method, with the transmitter and receiver located together in the instrument. In the reflection method, the acoustic wave is directed at a 90-degree angle toward a sufficiently large object having a surface that is as flat as p o s s ible , which reflects the acoustic pulse back to the instrument. In this situation, the acoustic wave natu- rally travels twice the distance to be measured. Most commercial instruments use a combined trans- mitter and receiver unit. Although this is a practical, compact and inexpensive solution, it does not allow very short distances to be measured, due to the transit time of the pulse. The instru- ment described here overcomes this difficulty. Although it also measures using the reflection principle, it has separate transmitter and receiver mod- ules. This allows it to measure even very short distances. The instrument is designed as a sta- tionary device, since the audio r mainly uses it for measuring the level of a liq- uid in a container. The transmitter and receiver are housed in a separate sen- sor enclosure, so they can be posi- tioned independently of the main por- tion of the instrument, Measurement principle Measurements are made continuously. A new measurement cycle is started every 200 ms. At time to of each cycle, the transmitter module initiates a 40- kHz pulse with a duration of 250 ps. The received signal is amplified as necessary and repeatedly sampled by the analogue -to -digital converter of a microcontroller, which initially stores the measured values in its memory. Sampling also starts at the initial time to and continues for 35 ms. After this, the software compares each of the stored 8 -bit measurements of the received signal with a threshold value. As the level of the received signal decreases markedly with increasing distance, the threshold value is corre- spondingly reduced as the sampling time increases. It must also be borne in mind that a rather strong signal is received while the transmitted pulse is being emitted and for a short time afterwards, due to direct crosstalk from the transmitter to the receiver and signal artefacts. Figure 1 shows an example of a plotted set of signal measurements and the curve of the threshold value. The evaluation software first deter- mines the maximum point of the sam- pled values, which is the sample that lies the furthest above its associated threshold. However, a strong reflection (at a short distance) will overload the receiver and the A D converter. As the actual maximum level of the signal will exceed the measurement range of the converter in such cases, the first meas- urement after the Initial time that exceeds a predefined overload level is taken to be the maximum point. The interval between the initial time and point where the two curves intersect before the maximum is then the transit time for the pulse, which is used to cal- culate the distance. To increase the accuracy of the measurement, the exact intersection point is determined using linear interpolation. Unfortunately, the speed of sound figure 1. Sample plot of signal measurements with threshold curve and overload level. 9, 'iCDS ■ cSAlcr elrctranfcs 45 HANDS-ON DISTANCE MEASURING Figure 2. The circuitry of ihe ultrasound distance measurement device, which is based on on Aim ego 3 microcontroller, is divided among three circuit hoards. depends on temperature, and more so than you might t hink . At 0 C it is approximately 331 m/s, and at 40 C it already reaches 345 m/ s. \j=33l\—[mls\ \ 273 where: T = temperature in degrees Kelvin V : = speed of sound at temperature T Consequently, the tamp era tore in the sensor head is measured using an NTC resistor, and the result is taken into account in calculating the distance. Tne temperature-dependent voltage drop is measured using an A/D converter in the microcontroller, in this case with 10-bit accuracy. The temperature range that can be measured in this manner is approximately -35 r C to -f44 Z C. The distance determined during each individual measurement cycle is not immediately displayed, but instead first compared with the results of previ- ous measurement cycles. No value is displayed unless the majority of the ten most recently calculated values lie approximately within the same range, in which case an average value is cal- culated and displayed. Tills makes the displayed value immune to isolated spurious measurements. Although the values are processed internally with a precision of 1/16 cm, the value that is ultimately displayed is in centimetres. The absolute accu- racy also depends on several ambient factors, such as the size and nature of the reflecting surface and reflections from other objects. Circuit description As can be seen from Figure 2 f the instrument is controlled by an AVR ATmegaS microcontroller. The micro- controller generates ihe measurement pulse on PD2 (pin 4)* Gpamps IC3a (inverting) and lC3b (non-inverting) 46 d skier zktronh - 9/2(105 iT LCD T 1 ei H ■n ■ 1 3 KS o ■2-L' j .'p — raise the voltage of the logic-level out- put signal to approximately 55 Vpo T which is the level required by the ultra- sonic transmitter (UT1). This level is obtained using a voltage doubler fonned by connecting IC3a and IC3b in bridge configuration. The reflected ultrasonic pulse is received by ultra- sonic sensor UR1, which has a reso- nant frequency of approximately 40 kHz, and then amplified by a factor of approximately 500 by op amps ICla and IC lb. A bandpass niter with a cen- tre frequency at approximately 40 kHz is incorporated in the amplifier stage to suppress any external interference signals that may be present. The ac portion of the output signal from IClb is coupled to rectifier diode D 1 via coupling capacitor C5. The rec- tifier diode is biased by voltage divider R5/R6. The positive half cycles passed by D1 charge smoothing capacitor C6 such that the voltage across C6 is pro- portional to the level of the input sig- nal The capacitor is discharged by R7. and the time constant of the RC net- work (C6/R7) is chosen such that the ripple voltage on the smoothed meas- urement signal is adequately sup- pressed. while still ensuring that the measurement signal decays within the shortest possible time. To improve the discharge characteristics, the dis- charge resistor is connected io -5 V instead of ground. At the maximum signal level, the resulting voltage at the input to the A/D converter in the microcontroller (PC 5 on pin 28) has a maximum value of approximately 3.7 V This makes the measurement signal compatible with the convener in the microcontroller. The temperature dependence of the diode threshold voltage is corrected by the software by means of periodic zero -point adjust- ment. This involves measuring the voltage at the converter input when no output signal is present on PD2 t so that no signal is received by the ultra- sonic receiver. All that remains to be ensured is that the zero level of the measurement signal does not drop below 0 V. even at the lowest operat- ing temperature (which is taken to be -25 'C for calculation purposes). At temperatures above this, the zero level is slightly above 0 V (approximately 150 mV at +45 ^C). The reference voltage for the A/D con- verter on the AREF lead (pin 21) f which is ecraal to rhe maximum volt- age of the measurement signal (3.7 V), is provided by the microcontroller via voltage divider R9/R10. The conver- sion is made using 8-bit resolution, which is fully adequate for this pur- pose. This allows the sampling rate to be set to the relatively high value of slightly less than 20 kHz (one meas- urement every 52 ps). The temperature is measured using MTC resistor R1 in the sensor head, The voltage drop across series resistor R2. which is proportional to the tem- perature, is measured using converter PC0 in the microcontroller (AD CO on pin 23) and included the distance cal- culation. Toe accuracy of the measure- ment also depends on the accuracy of the microcontroller clock. Conse- quently, the ATmegaS is operated using an external crystal instead of its internal RC clock oscillator. The computed distance in centimetres is shown using a time -multiplexed, three-digit seven-segment display (with common-anode display modules). The three seven- segment display mod- ules are fitted to a circuit board that is connected io K5 on the main circuit board via Kl. The decimal points of the display modules are not used by the current software, but for the sake of completeness, the hardware does allow them to be driven. 9/2005 - elsV tsi elstlfsnks 47 DISTANCE MEASURING figure 3-lhera me nine wire bridges m rtie mom circuit board, two more on ihe display board and one on the power supply board (next 1o 1C3). (topper layout available ham our website) Alternatively, a 2 x 16 LCD module can he connected. This display is driven m 4-hit mode. As the seven-segment dis- play and the LCD module share sev- eral port leads, a multiplex mechanism in the software allows both types of display to be used at the same time. In a manner of speaking, the LCD drive signals are interleaved with the drive signals for the seven- segment display. Trimpot Pi is the usual contrast adjustment trimpot for the LCD mod- ule. An optional backlight for the LCD can be keyed by a pushbutton switch in series with Ril. A 50 -Hz signal tapped off from the unrectified supply voltage and fed to the microcontroller via lead PC5 pro- vides a time reference for updating the date and time of day. The date and time are shown alternately on the LCD module. Interfaces An RS232 interface is essential for con- figuring the instrument settings or receiving periodic measurement data outputs. As n 15 V voltages are already present, we can do without the usual interface converter and use opamps IC4a and IC4b as drivers. The port lines are protected by internal diodes, so voltages greater than 5 V" or less than 0 V can be applied to them with- out causing any problems if suitable current limiting is provided (by R21). Tne six-way ISP connector (K2), which is an At me! STK500-compatible ISP6PIN connector, is provided to allow a prog rammin g unit to be connected for in-system software programming. This allows the circuit to be used as an ATmegaS development board, inde- pendent of its actual intended use. Jumper JP1 (VTARGET) should only be fitted if the programming unit does not have its own power supply and thus must take its supply voltage from the circuit it is connected to. JP1 should no rmally be left open. While progr ammin g is underway, the Reset line of the microcontroller is pulled Low. This causes all port leads that are not involved in serial pro- gramming to assume the high-imped- ance state (tri-state). To prevent the LCD module from placing data on the serial programming lines as the result of an undesixed read operation . the Enable line (E) of the LCD module is held Low via R12, The “5-V supply voltages are gener- ated on the power supply circuit board using 7805 and 7905 voltage regula- tors. Each of the necessary unregu- lated ±15-V supply voltages is obtained using a voltage-doubler stage consisting of charge pump Cl, C2. D! and D2 or CS, C9, D3 and D4, respec- tively The load on each of these sup- ply voltages is less than 20 mA. Construction and operation The circuitry for the distance meter is divided among three printed circuit boards and the sensor head. The sen- sor head contains the ultrasonic trans- mitter and receiver and the NTC resis- tor, all of which are wired point-to- point, Besides the main circuit hoard, which holds the microcontroller and the opamps for signal conditioning, the 48 riskter i icdrcmlQ - 9/2005 printed circuit board has separate sec- tions for the power supply and the seven-segment display. Before any components are fitted, the printed cir- cuit board must be separated into the individual sections. Start fitting the components with the wire bridges. There are nine on the main circuit board, two on the display board and one on the power supply board. As you can see, the wire bridges are the price that must be paid for using a single-sided circuit board with a compact component layout and correspondingly tight track routing. Tills makes it worthwhile to fit the wire bridges on the copper side using insulated wire. After this, the resistors, capacitors and 1C sockets, and finally the solder pins and the various connec- tors (headers, ISP connector and other connectors) can be fitted (on the com- ponent side, of course) and soldered using a soldering iron with a fine tip. Be careful to avoid creating any solder bridges. Fitting the components to the display board should not present any prob- lems. The display modules are not directly soldered to the board, but instead fitted in sockets so they pro- trude through the cover of the enclo- sure and stand higher than K1 together with its attached flat -cable connector. LCD modules come already assembled, so all you have to do is solder a flat cable to the module and plug it into K4 (or solder it directly to the board), A 13-way flat cable can be used, with every second lead being left open. The power supply board can also be put together quickly and easily. Here you only have to pay attention to the orientation of the components, since almost all of them must be fitted with the proper ‘polarity!. Given the low current consumption of the circuit, there's no need to fit additional heat- sinks to the voltage regulators. The 50- H z link is provided by a single solder pin (50 Hz) next to G9 on the power supply circuit board and a matching solder pin (PC5) on the main circuit board, close toIC2. The connection between the sensor head and the main circuit board must without exception be made using a single, screened four- way cable (a microphone cable or a quad cable for satellite TV). The connections for the two ultrasonic modules are distributed over several solder pins (PC1-PC4) on the main circuit board. The screens for the PC1-PC3 leads are twisted COMPONENTS LIST Power supply board Resistor: R1 = 33ka Capacitors"; O f C2,C6,C8,C9 - 220pF 25V radial C3,C5,C7,C10 = lOOpF 25V radial C4 - 47QpF 1 6V redid Cll - 10nF Semiconductors; B1 - bridge recimer 80V (or 40V). 0.8 A D1-D4 - 1N4001 1C) = 7815 IC2 - 7805 IC3 = 7905 IC4 = 7915 Miscellaneous: K1 = 5-way S1L header K2 = 2 -way PCB terminal block, lead pitch 7.5mm Tr l = mains transformer 2 x 6V @ 2 x 233mA (e g., ERA BV0307590.0U) FI = fuse, 63m AT (time lag), with PCB mount holder (lead pitch 22.5mm) (not required if a short-circuit resistant transformer is used) order code 04001 5-41 1C 3 = LM833M Miscellaneous; X i = 8MHz quartz crystal K i = 5-way pinheader and mating socket K2 = 6-way pinheader (2x3 black) K3 - 3-way pinheader straight K4 = 16-way pinheader straight ;<5 = 14-way (2x7) pinheader, straight K6 = 9-way D subminiature socket (female) Solder pins 1 off 28-way IC socket, narrow-DIL 3 off 8-way 1C socket 51 = pushbutton, 1 make contact LCD module 'with 44780 controller: 2x16 characters (optionally: with backlight; Display Tech 1 62) ABScase, min. inside dimensions 125 x 102mm jsplashproaf; approved For damp room / outdoor use] Display board ID1 ,LD2,LD3 - 7-segment display, common anode, 20mm high (Kinabright 5AQB-1 I 5RWA) K1 = 14-way (2x7) pinheader Main circuit board Resistors: R1 ,R3 = 3kU R2 = 6Skii R4 = 1 10ka R5 - 1 6kO R6 - 3kD3 R7 - 56kH R8 = 1 Oka R9 = 2700, 1% R 1 0 = 750Q, 1 % RT 1 = 330 R12 = 22kQ R1 3 r R16,R18 - 1 20kO R14 r R17 = 1 80kfl RI5,R19R2G = 82kO R21 = 47 ka R22 - 1 k05 R23,R24,R25 - 5kD6 R26-R33 = 270Q P 1 = 1 OkQ preset, H Capacitors*; Cl ,C3 = 2nF2 C2 = 27 p F C4 = 15pF C5 = 1 pF lead pitch 5mm or 7.5mm C6 = 33nF C7 = lOnF C8,C1 1 ,€12,04, 05,06,07 = lOOnF C9;C 1 0 = 22pf 0 3 = 22Qnb lead pitch 5mm or 7.5mm Semiconduclars: D1 = 1M4148 T1J2J3 - BC557A ICl ,IC4 = TL082P IC2 = ATmega8-i 6PC, programmed. Sensor head R 1 = NTC, 1 OkQ R2 - 1 2kQ, 1 % UT1 - ultrasonic emitter (36-40 kHz] UR 1 = ultrasonic receiver (36-40 kHz) 5-v/ay cable v/ith individual screening (eg. microphone cable); see text SplashprocF ABS case with strain relief grommet and locking nut (Bopla ET205, BF7, GM7) "All capacitors 5mm lead pitch unless otherwise indicated Ultrasonic transmitter and receiver Suggested sources and order numbers: www.maplm.ca.uk HY12N [recetver/iransmilter pair) www.cQnrad.de 400ST1 60/MA40-S 400ST 1 60/MA40-R www.reicheft.de 4O0ST1 60/UST40T 400SR 1 6O/U5T40R www.segar.de U ST-40 T U ST-4 0 R 182273-12 182281-12 UST40T U ST-4 OR U ST-40 T U ST-40 R www.simorts-elektronik.de \ UST-40T UST-40T | U ST-40 R U ST-4 OR ( 9/2005 - tlcldar dedronlcs 49 Table 1 Information shown on the LCD module A. If no maximum liquid level hos been configured (and during initial operation): rrr rrl ? r r2, r r -J ttiu tC ddddd B. ff the maximum liquid level has been configured using the RS232 interface: fff mt*tm hhh ppX ttt.tC ddddd rrr measured distance in cm rrl rr2,rr3 previous distance measurements, which shift to ihe right every minute Hi! current temperature in degrees Celsius ddddd date {dny.month) and lime of day (hoursimlnutes), shown alternately flf measured liquid level computed by subtracting ihe measured distance from the maxi* mum liquid level H1J12 previous liquid level measurements, which shift to the right every minute, hhh currently configured maximum liquid level pp liquid level In per cent (measured liquid level divided by maximum liquid level 1 00) together and connected to solder pin PC 4 (REC GND), where they also pro- vide the ground connection. Although the NTC connection via solder pins PC6 and PC7 is not sensitive to inter- ference, it's practical to use the remaining free leads (and associated screen) for this connection. It doesn't matter where this screen is soldered. Naturally, it should he prevented horn coming in contact with ihe other screen braids. This technique will only work if the individual screens in the cable are actually insulated from each other With cables that don't meet this requirement, a five-way cable most be used instead. The sensor head can be constructed using any desired enclosure that is suitable for the intended application. Naturally, there's no reason why the ultrasonic transmitter and receiver cannot be fitted a few centimetres apart in an enclosure, along with the NTC resistor and the other circuitry The two ultrasonic modules should be arranged such that they are as nearly possible parallel to each other. Don't overlook the lead for the 50-Hz signal between the power supply board and the main circuit board, since otherwise you won't see the time and date on the display For the RS232 interface, three leads are run from K3 to the RS232 chassis -mount socked, while the remaining connections are made directly to the socket. Initial operation If you initially operate the distance meter before it has been fitted in an enclosure, don't forget that mains volt- age is present on the power supply board. The best solution is to operate it using an isolation transformer. After the unit is switched on. the underline segments of the seven-seg- ment display will be lit for a short time before the actual measurement process starts up. You can hear the transmis- sion of the ultrasonic signals, although what you hear is of course not the 40- kHz oscillations, but instead the switch- on and switch -off noises the acoustic transducer produces when it’s driven by a pulsed waveform. If a minus sign (-) is shown on the seven - segment display, it means that no valid measurement value could be deter- mined. This error indication should dis- appear within a few seconds after the unit is switched on, and you should then see the measured value in cen- timetres. The information displayed on the LCD module is described in Table 1. Following these initial tests, you should check the indicated tempera- ture. As the value of an NTC resistor can differ from its nominal value by a relatively large amount (and usually does), the deviation must be compen- sated. A simple way to do this is to suitably adjust the value of series resistor R2 in the sensor head, or pos- sibly replace it by a multi-tum trim pot. If the displayed temperature is too high, the series resistance must be reduced. If you want to obtain accurate temperature or distance measure- ments over a relatively wide range of temperatures, you should use the RS232 interface to modify the Voltage to Temperature table. When the instrument is used continu- ously you should avoid exposing your- self and other creatures to the ultra- sound energy for coo long, even though people cannot hear the ultrasonic waves. To configure the meter via the RS232 interface, you must connect it to a PC using a 1:1 cable (not a nuli-modem cable). In the terminal emulator pro- gram, set the baud rate to 57. GOO (or 56,000) and configure the other param- eters as usual: 8 data bits, no parity, and 1 stop bit. After the meter is switched on, it issues a welcome message via the R3232 interface. After this, the date, time of day. temperature, distance or liquid level, and optionally the liquid level in per cent, are periodically out- put every minute. Pressing the Return key on the PC key- board sv/itches you into the command mode* which provides the following options as described in Table 2. Configuration 50 ekUn c!“£3rc“hi - 9/2005 IE ■ - -c ; Learning from bats The American Daniel Kish, who is now 38 years old, has been blind since the age of two. Despite this, he can orient himself in his surroundings almost as well as a sighted person. When he is in an unfamiliar area he makes a rapid senes of clicking noises and orients him- self using the echoes returned by obstacles. Dan Kish, v/ho Is called 'Batman' by his friends, has refined this form of echo orientation to the point that he can reli- ably distinguish the size, distance, and even the shape and spatial form of a large variety of objects and he can even ride around on a mountain bike. He has now started teaching his technique to other blind persons (see hjtp://wvAv.worldaccessfoilhe- blind.com/ L As persons who are just starting to learn this technique often find it difficult \o distinguish the subtleties of the echoes, Kish has developed a device to perfect the snapping sound. This is an embedded system' with a loud- speaker that can be fastened on the user's forehead like a miner's lamp. The circuitry produces a selection of clearly defined consistent clicks, which can also be made rather loud if necessary. The computer-controlled clicking Is far superior to the home-made variety, so the echo is up to three times as sharp. Industrial firms and research organisations hove also taken up this idea. Alcan, an international market leader in ophthalmic devices, found the design fascinating. They intend to market the device under the name 'SoundRash . The next-generation Soundflash units are planned to emit ultrasonic signals in addition to audible signals. The resulting echoes would thus also be satis- factory for bats. The only problem is that the device must feed the manifold details of the echo back into the human ear. The result is no longer an echo but instead an image of the echo that has essentially been shifted down in frequency, which the blind per- son must in turn painstakingly translate into a sort of spatial impression. The ability of the brain to naturally' perceive spatial quali- ties is restricted to the real echo in the audible spectrum. For this reason, Kish is now working with technicians and engineers to figure out how to generate a virtual model of the surroundings that the auditory system will intuitively perceive as being consistent. Scientists associated with the Chair of Sensor Technology of the University of Erlangen In Germany (http://vA i AvJse.uni-erlan- gen.de/fayout.cgi?page=Forschung/Projekt8] are presently working an the individual components of on artificial bat head. They plan to use it to study exactly how signals ore transmitted and received by bats. The objective of ihis study, which forms part of an EU project is to learn mare about abject recognition using ultrasound. The potential applications foreseen by the team lie primarily in the area of medical technology as orientation aids for blind persons. The mouth and ears of the artificial baf head will be able to be moved exactly the some as the mouth and ears of a real bat. Rotation of the head and ears Is the decisive factor in researching the ultrasound orientation system' explains Reinhard Lerch, a professor at the University of Erlangen. We are presently concentrating aur efforts an the ears, which pick up the signal, and on the port that generates the emitted signal and receives it/ The primary problem with this device is its size. Tn order to accurately reproduce the transmission and reception processes, the artificial head must be no larger than the original , says Alexander Stretcher, one of lerch s associates. The scientists are presently still v/arking to overcome another problem: they have not yet succeeded in realistically generating the entire frequen- cy spectrum of a baf (from 20 Hz to 200 kHz). Besides the characteristics of the ultrasonic transducer, the bat's ears ond their various shapes are the decisive rectors for recep- tion. To simplify construction, different types of bat ears were scanned using X-ray techniques, and computer models for the simu- lation ond plastic models for making measurements were generated from the stanned-in data. A computer program can then be used to determine the most favourable orientation of the ears, generate a suitable shape, and produce a genetic algorithm. d Set the date, t Set the time of day. h Maximum liquid level (distance from the sensor to the bottom of the monitored liquid container). Enter a value of 'O’ to display distance, v Calibrate the temperature measure- ment by modifying the Voltage to Tem- perature table. This table stores A/D voltages corresponding to specific temperatures (every 5 ~C over the range of -30 C to —45 ~C), The entered values must always increase with increasing temperature. A linear inter- polation is made between the entered values. An Excel table included in the software for thus project can be used to help determine the voltage values. p Continuously display the tempera- ture-sensor voltage measured at ADCO, o Calibrate the distance measure- ment, As the distance calculation depends on the current temperature, it 5 s best to calibrate the temperature measurement before calibrating the distance measurement. The distance calculation can be calibrated by enter- ing up to nine pairs of actual and nom- inal values. At specific distances cov- ering the entire range of distances to be measured, record the distance dis- played by the instrument together with the actual distance. For each cal- ibration point (pair of values in the cal- ibration table), enter the displayed value as the ho’ value and the actual value as the tout 1 value. Note that these values must be stated in units of one sixteenth of a centimetre, since the software uses this unit for its internal calculations and the accuracy of the calibration is improved by using the smaller unit. Consequently, the cen- timetre figures must be multiplied by sixteen. The pairs of values must be entered m increasing order, starting with the smallest ton value. As usual, the software linearly interpolates between the values entered for the individual points.. q Exit the command mode and return to the normal mode, in which the measured values are output every minute. V'/ith the exception of the date and time of day, all of the configuration data are stored in EE PROM, so they are not lost in the event of power failure. 9, 2005 - ehlt I oi etoirc'hu 51 REVIEW COPY The Z80, used extensively in the past, has been given a new lease of life by Zilog. Having kept a low profile for a while, this manufacturer has returned with a fast, modern controller. Paul Goossens One of the remarkable events of the eighties was the growth of the home com- puter market. The processor (CPU) inside most of these computers was either a 68xx series processor or a Z8Q. Well-known computers such as the ZX Spectrum and the MSX range used the latter processor. Since then most people have lost interest in these processors (and hence in Zilog). Since that time Zilog has concentrated on a different market, making dedicated processors for a variety of manufacturers. The Gameboy, for example, uses a derivative of the Z80. eZ8G Acclaim Zilog has recently returned to the spotlight with the introduction of several gen- eral purpose embedded processors. The newest arrival in this range is the eZ80 Acclaim family. This family currently consists of just three processors, one of which has a built-in Ethernet MAC. The inclu- sion or this goes to show which applications Zilog thinks this will be used for. A well-designed develop- ment kit with an eZ8DF91 is available at a reasonable price (around USS 100). eZ80F91 This new Z80 with an Ethernet MAC on board has been christened the eZ8QF91. Some of its more i mpo n a nt featu res are shown in the inset alongside. It is dear that the develop- ment of the Z80 hasrit stGod still and that this controller has a wide variety of extras. One of the more noticeable features is that the system bus is configurable, so that the controller can be used with hardware that was originally designed for use with a different controller. Of the features mentioned, the Ethernet functionality should prove very popular with designers, especially when all the other extras are taken into account! The kit For tills article we've taken a closer look at the *eZ8Q Acclaim Modular Development Kit', which was designed as an intro- duction to developing soft- ware for the eZ80F9i. Tills development kit con- tains everything you need (apart from a PC) to get started. We do miss the inclusion of an RS232 cable, which would have been use- ful although not strictly nec- essary. Most people will have such a cable lying around somewhere, so it's not a big omission really. The hardware consists of two parts: a small board with, amongst other things, the processor. 128 KB SRAM, oscillator, Ethernet connec- tor and two headers with all relevant signals. This board has been designed so it can be incorporated into your own circuits as well. 52 dcktcr ^stlFCdts - 9/2005 The second board contains JTAG, RS232 and program- ming connectors, along with a 3,3 V power supply. There is also the facility to connect a GSM modem to the mod- ule, This board also has all connectors required for it to be used in your own circuit. Software Apart from the hardware it’s the included software that can make or break a kit. In this case the accompanying software is more than ade- quate. On the CD ROMs are a full development environ- ment including a C compiler and a TCP/IP stack. Several examples are also included on the CDRGM, as Is a large amount of useful documen- tation, On top of this, the kit comes with its own operat- ing system based on XI NU, which is a multitasking operating system. In this case it has been extended with an API for using vari- ous features of the kit. This makes it easy to use the HTTP protocol and other Ether(inier}net functions. The fact that several tasks can apparently run at the same time makes this an appealing system to use and it makes it easier to write reliable software. Examples The examples included with the kit highlight the most important features of the new controller. The example that shows how individual tasks can be started and stopped is a very useful introduction to the operating system. The Webserver application will be of par denial interest to most users, because it is a perfect example of what the built-in Ethernet module and operating system are capable of. Expansion modules Should you feel that the kit doesn’t have enough I/O potential, you can always buy Zilog’s 'General purpose modular development sys- tem'. Many kits made by Zilog (including this one) can be connected to this. This kit adds a 2x16 charac- ter LCD, 4x3 keypad, A/D converter, a connector for a GPS module made by TVimble. and much more. And finally... The eZ30F91 and its devel- opment kit are certainly worth a closer look. Don't be fooled into thinking that this is an old-fashioned proces- sor given a new shine. It is in fact an up to date micro- controller suitable for use in many demanding embedded applications. If you would like to find out more about this controller, go to the m anuf a cture r 1 s webs it e (www.zilog.com) and search for the eZBOFQI. You will be rewarded with a large num- ber of application notes, cir- cuits and various other doc- uments. F a 1 1 i [ 1 I 1 I © SMTP i> — — — . TFTP FTP TELNET BOOTP OHCP © DNS © 1GMP • TIMER “S I 1 I 1 I I I 1 e ! Main specifications for the eZ80F91 © 50 MHz core # PLL • 256 Kbyte flash memory • 8 Kbyte SRAM O 8 Kbyte buffer for Ethernet MAC © 10/100 Mbit Ethernet MAC O Power management © SPI and I 2 C Interface © JTAG interface # 32 1/0 pins ® System bus configurable as a Z80, Intel or Motorola bus! © Watchdog timer ® Real-time dock © 4 enhanced timers m 2 DARTS © IrDA encoder/decoder © New DMA-like instructions Contents of the kit Processor module (with an eZ80F9l) and Ethernet connec- lion © Expansion board O Power supply j A CDR0M containing the Development Environment including an ANSK compiler, plus circuit diagrams, datasheets and a manual for the compiler 9 Quick-start guide ® A CDRQM with a complete TCP/IP- stack and documentation 9 Programming adapter [for the serial port) 5/20Q5 -ElckforcicfltedEs HANDS-ON Bosed on the MS5534 pressure sensor made by the Swiss company 1NTERSEMA (specialized in pressure measurements), with one metre resolution in altitude, this circuit will also give you absolute pressure, temperature, and even the time of day. The microcontroller used in the instrument is the now well established PIC16F876. Technical Features • Barometer mode at ±G.1 mbar [from 300 to 1JQD mbar) • 'Barograph' display of ihe tendency of the lost 4 hours • Altimeter/level meter mode at ±1 m f from -1,500 m fa +9,000 m) • low consumption (5 mA or 50 itA In standby mode) • Thermometer and dock • Output data la PC COM port at 9,600 bits/s Table I „ How to become a great weather forecaster dP/dl >2.5 mbar/h Clear unstable weather +0.5 Mono & Colour LCD's, ,/i e Touch Panels & Keypads, Very Low Power. 'll Target easily & quickly, nil ANSI ‘C’ compiler, assembler Inker all Windows32 based. » Source Level Debug. • ufl Driver Support with j Libraries. al Time Multitasking OS with a free run time licence. tE Unlimited email support./ 1 . | ;T« J 1 :J : ■ ~~L = '* ijrfn IjrM | [ 1 [41 * 11*1 rn t/Tf vjy] wgffiT v, rn.cms.uk.com see our web siie for full details CAMBRIDGE MICROPROCESSOR SYSTEMS LTD Unit 17-18 Zone 'D' Chelmsford Rd. Ind, Esi Great Dun mow, Essex CM6 1 XG Telephone: 01 371 875644 email: sales@cms, uk.com 9/2005 - HANDS-ON HOBBY Nico van Rooijen . _ ••• - - - r uc-i- A model racetrack is a nice toy for boys. Even the "big" boys like to race a little every once in a while. Of course, if is no V ' 'V- :~Fr * ' - • -v 'frv Li longer considered "playing 7 , but "amateur racing". If you then V - '.T- ^ ^ invite a friend for a match, the emotions can sometimes run high when it comes to deciding who crossed the finish line first. Here we present a circuit that can help you out in such situations. fastest? It is often the case that the dif- ference is easy to spot, but every no tv and then the front -runners are neck to neck and the w inni ng margin is so small that it is a “photo finish'. Installing a complete system of photo finish equipment on your model race- track is a possibility, of course, but that is possibly going just a little too far. A little less involved, but just as accu- rate, Is the following design. The circuit is, because of the use of a microcontroller, of quite a simple design. The microcontroller makes is possible to measure time very accu- rately and make the timing independ- ent from (a program running on) a PC, Because of the independence from a PC it is relatively easy to obtain an accuracy of 1/1 00 Oth of a second. In a PC there are a number of timers all running at rhe same time (such as sys- tem timer, USB timer, interrupts, etc.) which means that the accuracy can vary significantly. However, this does not matter to us now. Hardware Figure 1 shows the schematic of the hardware. D3 and D4 are infrared LEDs, These need to be mounted above the racetrack. Photo diodes D5 and D6 need to be mounted in the racetrack exactly opposite the LEDs so that they are in the best position to “see 4 the light from the LEDs (also refer to Figure 5). When a car passes by, the photo diode is (briefly) shielded from the light emit- ted by the LED, This causes a change in current through the diode and the passing of the car is then detected by 103. This dual op amp is configured as a comparator to compare the voltage across the photo diodes vrith a previ- ously set voltage (R3/R6). The microcontroller is a type 89C2051 and is clocked with XI ar 12 MHz. This is a high enough speed to accurately measure lap times down to 1 /1000th of a second. The program running in the microcontroller sends the lap rimes in ASCII to the PC. To connect the micro- controller to the PC we use a well- known chip from Maxim, the MAX232, Diodes D1 and D2 give a visual indica- tion when a passing car has been detected. Practical realisation Figure 2 shows the PCB layout for the circuit. The construction will rake very little effort end there is also very little to go wrong. Make sure you do not for- get the wire link under IC1. It is best to nt the (programmed) microcontroller in a socket. The female sub-D connecter is soldered directly on the PCB. The positioning of the LEDs and photo diodes on the track has already been discussed. Note that resistor R7 is not on the PCB , but is soldered in series with the LEDs. 62 eldt'ii clidicrlEs -9/2005 -5V Figure 1. The circuit diagram of the racetrack limer. p I COMPONENTS LIST I ! Resistors: R1 r R2 r R6 = 22 kQ 1 R3 = 2kQ2 I R4 r R5 = 1 ko i R7 = ) 80 I l Capacitors: | C1-C5 = iOpf 25V radial C6,C7,C8,CI \ = ICQnF C9,CT0 = 22pF Semiconductors; D1,D2 = LED, low current, 3mm D3,D4 = IR LED, e.g., TSU35202 D5,D6 = IR PIN photodiode, e.a., BPW4I 1C 1 = Al 89C2Q5 1-24PI, programmed. Publishers order code 040395-41 IC2 = MAX232 ICS = TLC272 k Miscellaneous: I K 1 “ 4-way 5IL connector I K2 = 9-way angled sub-D socket I (female), PCB mount [ XI = 1 2MHz quartz crystal I PCB, rer 040395- i from The PCBShcp ] (see www.elektor-electronic$ r co,uk] J CD-ROM, project software, Publishers | order code 040395-81 or free | Dosvnlc ad. | — — — — — — — — — — — — — — — j Figure 2. The PCB layout for the circuit. The RS232 connector is mounted directly on the PCB. Remember the wire link under 1C) when building! 9/2005 - e! skier dsttretfcs 63 HANDS-ON HOBBY Figure 3. Overview of the settings in the PC software. Figure 4. The program for the lop time and lap count in operation. For the power supply a simple regu- lated adapter that delivers 5 V will suf- fice. Toe current consumption of the IGs is quite small, about 20 mA. The current through the infrared LEDs is the lion's share of the required current (>100 mA). The connection with the PC is via a standard, straight through, 1:1 RS232 cable; i.e., not a null-modem cable. Software There are two separate pieces of soft' ware for this project: the software in the microcontroller and the software on the PC, The microcontroller that is available from us is already pro- grammed, but for those among you who would lihe to program your own or would like to know more about it can download roe source code free of charge from the Elekior Electronics website. Toe software for the PC can be found there tco : look for file number 040395-lLzip, All the software is also available on a CD-ROM with order code 040395-81, The PC software is well organised (refer Figure 3). Besides selecting the track, it is also possible to select the drivers. You can also indicate the cars that are being raced and which colours they have. In order to be able to choose between different tracks, drivers and cars there first have to be different tracks, drivers and cars. These you can create yourself via the menu 'Edit /Add 1 . At bottom left you need to indicate how many laps you will race. The Race!’ button leads to a screen- size overview, which displays the most important information (refer Figure 4). At the end of the race this nicely dis- plays all the details and announces the winner. This information can be saved to make other calculations or, or be used to tease your opponent. Finally: we wish you a lot of fun build- ing the circuit. And then much fun rac- ing, of course, because that's what started it ail! Figure 5. A suggestion for a practical Implementation. Here a photo diode is built into the track between ike finish line and the concluding strip, in front of the white tar. safety guidelines 1. Use a mains cable with moulded’ on plug. 2. Use a strain relief on lbs mains cable. 3 . Affix a label al the outside of the enclosure near the mains entry stating the equipment type , the mains voltage or voltage range, the frequency or fre- quency range. and the current drain or curenl drain range. 4. Use an approved double- pole on/ off switch, which is effectively the 'discon- nect device \ 5. Push wires through eyelets before soldering them in place . 6. Use insulating sleeves for extra protection. 7. The distance between transformer terminals and core and other parts must he >6 mm . 8. Use the correct type , sire and current-carrying capacity ol cables and wires - see shaded table below. 9. A printed-circuit board like aft olher parts should be well secured . All joints and connections should be well made and soldered nealfy so that they are mechanically and electrically sound , Never solder mains-carrying wires directly to the hoard : use solder tags. The use ol crimp-on tags is also good practice. 10. Even when a Class it transformer is used , it remains the on off switch whose function if is to isolate a hazardous voltage (Le.. mains input) from the pri- mary circuit in the equipment. The primary-io-secondary isolation of (he transformer does not and can not perform this function. in all mains-o aerated equipment certain important safety requirements must be met. The relevant standard for most sound equipment is Safety of informa- tion Technology Equipment, including Electrical Business Equipment (Euro- pean Harmonized British Standard BS EN 60350:1992). Electrical safety under this standard relates to protection from * a hazardous voltage, that is, a volt- age greater than 42.4 V peak or 60 V dx,: * a hazardous energy level, which is defined as a stored snerg , level of 20 Joules or more or an available continuous power level of 240 VA or more at a potential of 2 V or more; * a single insulation fault which would cause a conductive part to become hazardous; - the source of a hazardous voltage or energj level from primary power; * secondary power (derived from Internal circuitry which is supplied and isolated from any power source, including d.c.j Protection against electric shock is achieved by two classes of equipment. Class 1 equipment uses basic insu- lation ; its conductive parts, which may become hazardous if this insulation fails, must be connected to the supply protective earth. Glass II equipment uses double or reinforced insulation for use where mere is no provision for suppl < protec- tive earth i rare in electronics - mainly applicable to pow er tools). The use of a a Class II insulated transformer is preferred. Put note that when this is fitted in a Class I equip- ment this does not by itself, confer Class II status on the equipment Electrical^, conductive enclosures that are used to Isolate and protect a hazardous supply voltage or energy level from user access must be protec- tively earthed regardless of whether the mains transformar is Class i or Class It Always keep the distance between mains-carrying parts and other parrs as large as possible, but never lass than required. If ai ail possible, use an approved mains entry w ith integrated fuse holder and on off switch, if this is not avail- able. use a strain relief (Figure, note 2) on the mains cable at the point of entry. In this case, the mains fuse should tre placed after the double-pole on off switch unless it is a Touchpmof I type or similar. Close to each and every fuse must be affixed a label stating the fuse rating and type. The separate- on off switch (Figure, note 4}. which is really a disconnect device', should be an approved double- pole type (to switch the phase and neu- tral conductors of a single-phase mams supply In case of a three-phase sup- pSy, aSi phases and neutral (where used) must be switched simultaneously, A pluggable meins cable may be consid- ered as a disconnect device In an approved switch, the contact gap in the off position is not smaller than 3 mm. The on off switch must .be fitted by as snort a cable as possible to the mains entry point. All components in the primary transformer circuit, includ- ing a separate mains fuse and separate mains filtering components, must be placed in the switched section of the primary circuit. Placing them before trie on off switch will leave them at a haz- ardous voltage level when the equip- ment is switched off. If trie equipment uses an open-con- struction power supply which is not separately protected by an earthed metal screen or insulated enclosure or otherwise guarded, all trie conductive parts of trie enclosure must be protec- tively earthed using green yellow wire (green with a narrow' yellow stripe - do not use yellow wine with a green stripe). Trie earth wire must not be daisy- chained from one part of the enclosure to another. Each conductive part must be protectively earthed by direct and separate wiring to the primary earth paint which should be as close as pos- sible to trie mains connector or mains cable entry. This ensures that removal of the protective earth from a conduc- tive part does not also remove the pro- tective earth from other conductive parts. Pay particular attention to the metal spindles of switches and potentiome- ters: if touchable, these must be protec- tively earthed. Nate, however, ihai such components fitted with metal spindles anc or levers constructed to the rele- vant British Standard fully meet all insu- lation requirements. The temperature of touchable parts must not be so high as to cause Injury or to create a lire risk, Most risks can be eliminated by trie use of correct fuses, a sufficiently firm construction, correct choice and use of insulating materials and adequate coal- ing through heat sinks and by extractor fans. The equipment must be sturdy: repeatedly dropping it an to a hard sur- face from a height of 5Q mm must noi cause damage. Greater impacts must nrn loosen the mains transformer, elec- trolytic capacitors and other important components. Do not use dubious or flammable materials that emit poisonous gases. Shorten screws that corns too close to other components. Keep mains-carrying parts and Vi .res well away iram ventilation holes, so that an intruding screwdriver or inward falling met a! object cannot touch such parts. As soon as you open an equipment, there are many potential dangers. Most of these can be Eliminated by discon- necting the equipment from the mains before the unit is opened. But, since testing requires that it is plugged In again, it is good practice (and safe) to fit a residual current device iRCDr rated at not more than 30 mA to the mains system (sometimes it is possible to fh this inside the mains outlet box or multiple socket). " Sometimes called residual current breaker - RGB - or residual crrcuft cur- rent breaker -RCCB. These guidelines have bean drawn up with great cars by the editorial staff of this magazine. How e ver, the publishers do noi assume, and hereby disclaim, any liability for any loss or damage, direct or consequential, caused by errors or omissions in fee guidelines, whether such errors or omissions result from negligence, accident or any other cause. 3-care mains cable to BS6500 1990 with three stranded conductors in thick PVG sheath Max current 3 A 6 A 13 A conductor size 16 0.2 mm 24/0.2 mm 40/0.2 mm Mom cond area 0.5 mm2 0.75 mm 2 1.25 mm 2 overall cable dla. 5.6 mm 6.9 mm 7.5 mm Insulated hook-up wire to DEF61-12 Max current 1.4 A 3 A 6 A Max working voltage 1000 V rms 1000 V rms 1000 V rms PVC sheath thickness 0.3 mm 0,3 mm 0.45 mm conductor size 7 0.2 mm 16/0.2 mm 24/0.2 mm Nam cond area 0,22 mm 2 0,5 mm 2 0,95 mm 2 overall wire dia 1 >2 mm 1,5 mm 2.05 mm 3-flat-pin mains plug to BS 1363A 65 tickler efEdrc-iiKs - 9/2005 CAPW 1 EWutJyTi' C^p Ot '■? 47-32Qjitf IM5V). fttSOTl losopcr vittad RfcSiiltK ITU {Oft "1 QM DJZ5W 1 %] £4.99 CAP-O02 lMfptiPtViter (>p*£fcGf Kh i i-47Dfif &&) CAf -W3 ZSGpCi Cerirrijt Ci^iscftflf Krt (4_7flF- itfinf S0V) Mi SWD-002 90Cpci Suite Capagtof Kjt it bF-IOG^ 50V1 1 SAACH501 lIMpu SvfKV Unt fr^oTor re EOft-i wyw s%* Mbs! order P&P: £2.50 (Free PiP orders over £20) uiuiui.fa5tcomponEnt5.co.uK Teh 0870 750 4468 Fax: 0870 137 6005 LL U_ O “ m 1 See 2 gai t goE? O oS8 C O a.~in gyo U_ a-3^ ■ j £jrO_(AI z?sQ ^ ^ n £l in s ^ o'* Ifl o O ANDRE LaMUTHE’S X Gam eS tat/o n LfAtfN STEF"eT-STEP HOW TO BltjlD wo oe^itHM Vmjie owjvt vaoeo game console.’ t>e^sn inspired by 0 io . j ■ _ Atari S00 2600, Sinclair ZX 3 peclnun i App 'e II & Commodore 64! FWaKiu SXKcy Cocr^ji«*ri - ' mOWDES: % // -. 'Too*5,D=fli i • . 1 1 ■ ij >jff rid? h _ operation of electron lubes, while the first chapter gives a short history of the valve. ISBN 0 905705 39 4 253 Paces £15.55 (USS31. 00) Modern High-end Valve Amplifiers Valve amplifiers are regarded by many to be the ne plus ultra when it comes to processing audio signals. The com- bination or classical technology and modem components has resulted in a revival of the valve amplifier. The use of toroidal-core output transformers, developed by the author over the past 15 years, has contributed to this revi- val. This book explains the whys and wherefores ot toroidal output transfor- mers at various tech- nical levels and offers innovative solutions for achieving perfect audio quality, ISBN 0 905705 63 7 264 Paces 25.95 (USS52.00) Build your own High-End Audio Equipment The name high-end equipment is a good indication of the prices charged for it. For those who cannot, or wilt not. pay these high prices, there is a solution offered in this book: build your own at considerable cost savings. This book is aimed not only at this sector of the market but also at the many enthusiasts who want to be able to experiment and to make their own modifications to their high-end equipment. Contents include solid-state and valve preamplifiers and power amplifiers, active cross- over filters, an active subwoofer, a headphone amplifier and more. ISBN 0 905705 40 B 262 Paqes £15.55 (USS31.00) 66 iWmi ekmcvics - 9 2005 Visit our website www. distel.co.uk 1 THE ORIGINAL SURPLUS WONDERLAND! | THIS MONTH'S SELECTION FROM OUR VAST EVER CHANGING STOCKS Surplus always wanted for cash! GIANT 10” 7 SEGMENT DISPLA YS I IC’s -TRANSISTORS - DIODES A purci\55£ enables to- fcrirjg fin ■ ~-_i G?A* . i 7 S eat&t ccS DSifir.3 ai a ^fTrx ri^h U :hce" he 10' character size EKSfj&ysf resd- zfafiy s* tore :~ji~ ies ana oraihiias s rostofsp^s- :cr:i rccora scorn bsarris riig/teJ docks, coun- ters event timers etc As ire Ltftois se 5 ampfe ejs^recraned devise and operate ton 12 V DC, arspfe sweeting wa switehes, fssys. PtC cr PC may .^F-ito A' - -' i 'D -r :ca _ tz toz - .. - : vtie&sL Zero na^ rrermy uhd) _iijjiwu_. JtE j- -■:■ a - excellent ELY practical article r 1 . f ^ ii_e : : ■Everyday & Practical BecarcifMes'jriagazIne kJe=! 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Braid rtv; - iJEy gt^-atossa. TELESOX ST for oemposte video input type mtxtilors £36.95 TELEBOX STL as ST but fitted with integral speaker £39. 50 TELEBOX MS ktuitajand VHFiUHFiiZahte/HypefttiTid timer £69 9 5 For overseas PAL versions state 5.5 or 6 mHz sound spsc^-catkwi. 'For catjfe / hyperitand signal reception Tefebaic MB should be con- ~DZ:CZ to -. T Llr It S" == " I I" =~ T C -ZZZ . S ‘ M-S B Stale of the ait PAL (UK spec] UHF TV tuner module with composite IV pp video S N3CAM ht fi stereo sound outputs. Micro electronics all on one small RGB only 73 x ' = !_.■ =- t :_■• ■; ► a s simple 3 wl/e link :rj sn IBM pc type computer, Suppfed corr^jlete with simple working program and docunentatioa. Requses +12V & + 5V DC to operate. ERA IJD NEW - Or* r as AJ YOQ. 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' & SCSI RFE tested £39.00 HP C301Q 2 Gb .te SCSI differential Krc ieated £195.00 NEC 0224S 35 7, f t> S Y D nterface . Now £99.00 FUJITSU M2322K 160?, in S\*D l F RFE teS'Sd £195 DD FUJITSU U2392X 2 Gd SMD I F RFE tested £345.00 Many other floppy 3. H drives. IDE . SCSI. ESDI ere from stock; sec- website for full stock list . Shipping an all drives is code (C) OBSOLETE - SHORT SUPPLY - BULK 10,000,000 items EX STOCK Few MAJOR SAVINGS CALL or see web site www. distel.co.uk COMPUTER MONITOR SPECIALS Legacy products High spec genuine multysync. CGA, EGA : VGA. SVGA Mfeub&hJ FA3415ETKL t 4 " S', 3- lit uftrsync dchio - monfirr w^r: nna 023 (fc£ pffih lis and tesoiicn t> 1024 x 768, A vsn- sb/ t with 16 1*Qjyle SIMM. AMI I BIOS, battery backed ip real time dock. 2x9 pm D 16550 serial ports. 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A mains dis- tribution panel ntefna .. nwchted to Te l-lzit rear, pnmdbs 8 x I EC 3 ptn Euru sockets and 1 x 13 amp 3 pin switched utility socket Overall ventT.a- Hon Is poKdttod by fully fawned hack door and dwi Wg skinned top section with top atd ade louvres The top panel may be removed for fitting of integral fans to the sub plate etc. Other features indude: fitted castq?s and ftow leveJejs, preponched utfity panel at krwer rear fur cahte / connector access eto. Supplted to excellent. sHQhtiy used condition with keys. 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ONLY £89.00 s ENCARTA 95 - CORO.'it. ,'iot the latest - but at this Dfice ! £7.95 DOS 5,0 cn 314” disks with conoise books eftv CJ Base . £14.95 Windows for Workgroups 3.11# Dos 6.22 on 3-5 1 " disks £55.00 Windows 95 CDROM Only - Ho Licence - £19.95 WordPerfect 6 tor DOS suppfed on 3T4T disks with manual £24,95 shipping charges for sofrware is cede B SOLID STATE LASERS V.f : t TEd, G 7 C - " asc : ::a ^ ^ - _ ■ ■ = “T : — £ .2" a: approx SO mA_ OrigingSy rnsde for ccrifetiots use in evfustrial bar- code scanners, fee laser is mounted in a ttemovabie softl a-tpranfem btocSc which fencsBons as a heatsink and rigid optical mount Pirns of btock are 50wx5Q"j Spice Simulation option im Product variants to suit your budget Runs on Windows systems including XP Version 9.0 now available Call us on 01684 773662 SO efeklof efettior-ics - 9/2005 products and services directory NEW WAVE CONCEPTS PICDOS TI'E vv .v w. new - m m -coficep ts. co m Software for hobbyists: * live wire circuit simulation software, only £34.99 • PCB Wizard circuit design software, only £34.99 Available from all Maptin Electronics stores and vwvLmaplin. co.uk. PCB WORLD http: www. pcbwGild.org uk World-class site: Your magazine project or prototype PCB from the artwork of your choice for less. Call Lee on 07946 846159 tor details. Prompt service. PHYZX hiip: wvay. plcdos.com Hard disk, DOS & riles on PIC16F877. SmariMediaTM based. Mo complex hardware just wires. Run-Debug existing PIC code & interrupts. Free schematics, software, debugger ■, JCf QUASAR ELECTRONICS v/w w.QjjosarEiectf onlcs.com Over 300 electronic kits, projects and ready built units for hobby, education and industrial applications QUASAR including PIC/ATMEL electees programming solutions. Online ordering facilities, Tel: +44 (0)870 246 1826 Fax: +44 (0) 870 460 1045 Email: saies3QuasarElectronics.com http:, www' pnyzx.CQ.uk Automatically Plot and Drill PCS’s * Accurately • Repeatably * Mains operated « Robust Steel Construction ■ Gerber RS274X compatible * Full XYZ RS32 Control ■ Including Accessories • Complete sytem Under £500. ROBOT ELECTRONICS h tip : . www: ro b ot- e I eetron i cs .co. u k * Ultrasonic rangefinders * Motor H-Bridge controllers * Magnetic Compasses * RC servos and controllers * PIC programmers and components * Electronic Design/Development and Manufacturer to industry SHOWCASE YOUR COMPANY HERE Etcklor ElL+uuniL-> hu_s a feature to help customers promote tlieir business. Showcase - a permanent feature of the magazine v. Etc re \ on \\ ill he able to showcase your products and services. • For ju*i £220 + VAT 5 £20 per issue for eleven issuer * Elekiur will publish your company name, website a dress and a 30- word de scrip dun ■ l : or £330 + VAT for the year I £30 per i"*ue for eleven issues i we will publish die above plus run a 3cm deep full colour image - e.g. a product shoL a M+een shot from your site. a company logo - your choice Places are limited and spaces u ill go on a siricLh tiTM come, first served basts. So please fax back your order todav l I wish to promote my cam panv. please book my space: * Jew insertion only for £220 + VAT * Text and photo for £330 - VAT ------ - - - -- - 1 i _ . j _ _ .......... JOB TITLE:..... ADDRESS: .........ORGAX IS ATI ON: , - ......................................................... . i ...TEL: .... .. [ PLEASE COMPLETE COUPON BELOW AND FAX BACK TO 0044-1 0 1 1 932 564998 [ COMPANY NAME * WEB ADDRESS 1 30AVORD DESCRIPTION........ k — j SYTRONIC TECHNOLOGY LTD www. m 2 m telemetry, c om Supplier of wireless modules and accessories for remote monitoring M2M apolicafions. * GSM/GPfttTCP/iP modules * Embedded GSM GPRS modem * Development Kits * GPS modules * GSM r GPS antennas * Adapter cables Online ordering facilities. Tel (01394) 210911 ULTRALEDS U1 tr ' sIeds —‘ http: v wTAY.u3traleds.co.uk tel: 0871 7110413 Large range of low cost Ultra bright leds and Led related lighting products. Major credit cards taken online with same day depatch. USB INSTRUMENTS h ftp: : www . us b - ins iru me nts.c USB instruments specialises in PC based instrumentation products and software such as Oscilloscopes: Data Loggers, Logic Analaysers which interface to your PC via V1EWC0M brio: ■' wyay. viewcom.f9-co.uk tel: 020 8471 9338 fax: 020 8552 0946 • Mail Order supplier of: • Integrated Circuits and Components. • Kit and parts for Elekior projects. • Transistors. FETs, Capacitors, Resistors, Crystals, etc and hard to find devices. Viewcom Electronics. 77 Upperton Road West, Plaistow, London El 3 9LT VIRTiNS TECHNOLOGY n“pj www;, imns.com PC based virtual instrument for electronics enthusiasts, students and professionals, including full-fledged sound card real time Oscilloscope, Spectrum, Analyzer and Signal, Generator, Oownloader and try. ELECTRONIC ENTHUSIASTS Only one magazine tests its projects and orojjEs in its own iah before publication f Contact; Worldwide Subscription Service Ltd, Unit 4 Gibbs need Farm, Pssfiley i?oad r Ticehurst TN 5 7 HE Telephone: 01 SQO 20GS57 Fax: D15SO 2006 f 6 vn'^v.e Jeklor-erectronici.co.uk 9, 7005 - tlcklar 81 CD-ROM 3 iSTSEL ERS Robotics A large collection of data- sheets, software tools, tips, tricks and Internet links to assorted robot constructions and general technical infor- mation, All aspects of modem robotics are covered, from sensors to motors, mechanical parts to microcontrollers, not forgetting matching program- ming tools and libraries for signal processing. £12.05 (USS 21.25) ECD Elektors Components Database gives you easy access to design data for over 5.700 ICs. more than 35,000 transistors, FETs, thyristors and triacs, just under 25 r 0Q0 diodes and 1 .800 optocQuplers. All data- bank applications are fully interactive, allowing the user to add. edit and complete component data, £12.95 (USS 22.90) Elektor 2004 This CD-ROM contains all editorial articles, with the exception of New Products items, published in Elektor Electronics magazine Volume 2004. Using the supplied Acrobat Reader program, articles are presented in the same layout as originally found in the magazine. The DiskMirror utility on this CD-ROM allows your earlier Elektor year volume CD-ROMs (1997-2003) to be added to a large archive on hard disk for fast access and easy reference. A built-in search function allows you to find refe- rences in any article from the archive on hard disk, or from individual year volume CD-ROMs you have available, £16.25 (USS 28.75) Order www.elektor-e Order now using the Order Form in the Readers Services section In this issue. More information on www.elektor-electronics.co.uk PC-lnterfaces under Windows PC Interfaces can be used for more than just the printer, mouse, modem and joy- stick! While it was relatively easy to directly access PC interfaces using a DOS com- puter. under Windows things are not all that simple. This book (CD-ROM inch) shows you how it can be done. The authors describe the DIY construction and programming of a number of highly interesting circuits. ISBN 0-905705-65-3 * 265 pages • £25.95 Lasers: Theory and Practice LASERS: j HEO RY A SD PRY CTtCE This book is written for a wide readership. It consists of two main parts. The first deals with the fundamentals of lasers, including such topics as types of laser, modes of laser operation, wavelengths, chopping, scanning, and applications. The second part contains a number of highly interesting practical circuits and experiments. ISBN 0-905705-52-1 * 180 pages * £20.75 ■g-^yvi ■ i i Si I JL P « 4 . _J * J r I . Ef. * n fry © © © © PC-lnterfaces under Windows ISBN 0-905705-65-3 £25.95 | — Build your own Audio Valve Amplifiers ISBN 0-905705-39-4 £15.55 Dictionary of Monitor Technology ISBN 0-905705-64-5 £25.95 Modern High-end Valve Amplifiers ISBN 0-905705-63-7 £25.95 BESYgYLUNK© 3O011C© JULY/AUGUST 2005 Top -5 © 308 Circuits ISBN 0-905705-66-1 £18,20 308 CIRCUITS More information on www.elektor^electronics.co.uk (June iUUo ) Ready-built PCB (excl. enclosure) 050008-91 £ 50.00/ S 94.25 Complete kit (not inclu ding IC3) with Lassen iQ-receiver and extra long cable. CD with software and water- proof antenna case. Matching enclosure 050008-71 £ 10.25 /S 19.30 040264-71 £ 77.65 /S 146.25 Elektor Electronics (Publishing) P.O. Box 190 Tunbridge Wells TN5 7WY ENGLAND Telephone +44 (0) 1 580 200 657 Fax +44(0)1580 200 616 Email; saies@elektor-eiectronics.co.uk inline at lectronics.co.uk Due to practical CGnsframts, Final illustrations aiMi specifications may differ Irani published designs. Prices subject to change. See Yrfww. ef eklp r- eleclronics co. uk for up to dale information. & Modules OBD-2 Analyser (juiy/August 2005 ) Kit of parts including PCS, programmed controller, compo- nents (including IC7 ; IC3 = PCA82C250, 12 V), enclosure and RS232 cable. OBD cable not included. 050092-71 £ 52.50 /S 96.95 OBD cable 050092-72 £ 27.55 /$ 51.95 ESR/C Meter (September 2005) Kit of parts including PCB. default LCD module, 2x16 characters and programmed controllers. Enclosure not included. 040259-71 £ 63.99 /$ 119.95 Matching enclosure 040259-72 £ 6.99 /S 12.95 Further products from Elektor Electronics: READY-BUILT PROJECTS £ S ClariTy 30Q-W Cfass-T Amplifier 030217-91 Ampler board wilft SMDs pre-fiffed; cores for Li ft L2 34-50 55.70 Ffash Microcontroller Starter Kit 0102C3-91 5 j “CE isim- adapter ft rented art>.‘ss 69 00 112.50 Gameboy Digital Sampling Oscilloscope (GBDSO) 990082-91 re = -/-assembled board. ind_ the PC software arxi related aitides 1 03-00 1 83.00 LPC210x ARMee Development System 0404 -Li-? i = r: -r-iasor Dear x ready-m ads and tested Micro Webserver with MSC1210 Board 030G60-91 '. r creprocesspr Dzar_. fesdj-eSseTiiiB : 044 026-5 1 ' - si v, o r < E'«:ens -:r, £ : ar a y*ass =~z ed 044026-92 Combated package (030060-91 ft 044026-91 ft related artiefes) 25-50 75-S0 44-50 117-50 4805 142.55 83.95 220.95 1 EVERGREENS Elekiar electronics Help Disk S66022-1 D ; k i 4 ; , WA5 i a rskfn 8-15 14.45 Elektor Electronics Item Tracer 1985-2003 046OO3-11 cante-ts database iosEa iV.ndOAS ver&cni fr15 14.35 Universal Prototyping Boards UPBS -1 PCB 2-45 4.30 UPB5-2 2 PCBe. 410 7,25 UPBS-4 - RGBs £-55 11.55 INo. 346 SEPTEMBER 2005 ESR/0 Meter 040259-1 PCB, nsre 1240 23.35 340259-11 D *•; AC source i hex cedes 5-20 9.75 Q40 259-41 = C 6 "577 -20 r. pteg ramrr es 15-50 29.25 340259-42 P l I ‘£-7- 4-2 CP pr og irrsd 10 30 19.45 04 025 9-71 *, t c : parte & *r :■ j! trz : . : s-a r*n 63-52 119.95 040259-72 ma::. 6-99 12.95 Hitting the High Note G40Q1 5-4 1 ATrr 2936-1 6 F C , p rogf ammed 15-50 23.25 04OO' 15-11 0 &K. P fOCM ! sc 'tvrafe 520 3.75 Precision Barometer/Aflimeter 04O3 13-11 D'sk. c re- set sc ftware 5-20 9.75 040313-41 P1C16F376. programmed 16=5 31.15 040513-1 PC3 7-55 K,25 Racetrack Timer 040395-41 AT89C2C5 1 -24P! 6 65 12,95 04 0 395*3 1 CD ROM . p reject safhva re 515 5,75 No. 345 JULY/AUGUST 2005 1 MHz Frequency Counter 030045-1 1 D :&l p re ;=ct ssftw are 5-20 9.75 02JXA5--1 A7503231 3-1 DPs p'cgjanzrrsd 5-50 10,75 Code Lock with One Button 040431-11 D scarce ft Fib* F bb 5-20 975 040481-41 PIC16FS4, pnz-3'amT*ed £<-£5 12.95 Digital VU Meter 0501 18-11 D s? .. . Ail Hr, E : ftw a re 5-20 975 0S6 ' ".2- 5L, if a: : 3 40 b.4 & DJL/SOIC/TSSOP Adapter Boards 040263-1 PCD. far 20*way DID IG 6-75 12,70 040233*2 : r 20-Vi Sv 5 D C : C 575 12.70 040259-3 PCB, fer ££hray 73SOF 1C 675 12.70 MP3 Adaptor for TV 054035-i PCB. Safe 3-95 _ e: 054035- 1 1 0 i k p rc^z t i: tw are 5-20 9.75 C64 035-3 1 EFM 7064 S LC44- 1 0 . p reg r. ol 27-55 51.95 OBD-2 Analyser 050092-1 PCS. bare 3-95 teas 050002-4 1 T63C 51 C C02U 4 u :: ram msd 25-20 49.40 O50O92-7 1 ■ ! cf p arts cat - 52-50 05 55 Products for olderprojects (if available) may be found on our website www.elektor-electronics.co.uk home construction = fun and added value UrTTr ill'M'lllI Mill SNEAK PREVIEW I: Security Security is a BEG issue these days, covering the protection ol your home, valuables, sensitive data, Family, computer, Internet connection, cor and or course yourself! in the October 2005 issue we will discuss several practical, electronics- related aspects of security* For example, our lab is work- ing on an electronic ringsrpnni reader and a handy detector for counterfeit Euro banknotes. 27C512 Emulator An emulator is a handy tool tor developing microcontroller soft- ware* In this case we not only look al the end result but also at the underlying design process. Our starting point is the applica- tion of an Altera CPLD in order to keep the component count to a minimum* Tne CPID is assisted by an AT9QS8515 microcon- troller. An instructive article for oil of you wishing to gain experi- ence in designing CPLDs into circuits! Remote Control Operator They're everywhere, wireless remote controls for home and utility lighting! Complete sets of lamp switches and a master remote con ItoI can be bought at knockdown prices from builder's markets and highstreet electrical outlets. It all adds to the comfort of controlling everything from your chair or couch. However, with security In mind, is it passible !o switch the lights on and off- in your absence and so deter burglars? !t is, using the small extension circuit we've designed. Theme Plan for 2005 January . . . . .Power Supplies February * * . .Wireless March .Sound April ...... .Microcontrollers May * .Sensors June ...... .Environment July/ August . .Summer Circuits September . , .Test & Measurement October . ■ .Security . : November . . .CAD Software December * . .Optoelectronics Also... Colossus 2-way Data Encryption Unit; RESERVE YOUR COPY MOV/! Tht October 2005 issue gees eet sofe m Seturdey 24 September 2005 (UK distribution only). Delphi Course pan 8 PC Flash Dangle. UK subscribers wiU receive the ruagoiine o few days before ibis dole. Article titles and magazine contents subject to change. Your price conscious PCB supplier Verified CIRCUITS - pooling for prototypes and small senes - from 1 tilt 1,000 pieces - from 4 working days onwards - up to 6 layers Online Price calculation Online Ordering Online Order tracking Online 24/24H and 7/7D a ia carte - wide range of technological capabilities - up to 20 layers - from 1 piece onwards - from 2 working days onwards www.eurocircuits.com MEGApooi - pooling for series - 250, 500 or 1.000 pieces - medium series at prices of MEGA senes Index of Advertisers AUsjehhJ Tecfroatogy. Showcase 80 Aurifopress. Step crease - .;vwv, audit* 'sss.ee ... 80 Avit Research * tv.vv/.dMfrBseartf: co.uk **._..*. .6 Beta Uyotn. Showcase . . s,a-,\.z:z-z:. com 8. 80 Bitscops Designs . . * Gr/scops. com 17 Qrradtosrriiiig Systems ......... ;.wv, pres d tosreng zoo*. ......... .3 ,w,\V'.cori}pii<:u:'&5.cGm ....... .www :c rS crtf&-e£.coAtk iv k w. Ih’-jiginihepaSL dcm&n.CD. ith r 1 I ■/ .i'S-f ■ CD Ur Burn Tc cTmc'oov LTD, Showcase CMS Compuctri, Showcase Cc-niD-G Bsctmn ss. Showcase Crickle wood .... * Danbury, Showcase . Display Electronics . . . Eesysync. Showcase EIhe-c, Showcase Eurocirctiils , . * . * EmhsssFGB Fast Components Forest, Show case Future Tectmotogy Devices, Showcase . . jMm.fidrctiiP'COfn Futurtec, Showcase ... ft/fcrriec . com ILP Electronics Limited. Showcase .wv.'rV.c:.- rr7 ‘5“ com 80 .AVAV.CfTlS.L^LCDni . 61 .svwVi easysj ~c :: J , . mViYzIft&ccufn ym T iY.£um£h£ui& com . . ' i . emrmspcbxCQm . fe/eompewenfe co.uk _ V A. fares. co.isk BO ....BO 66 ... 60 , . . .67 -.7,80 SO ... B-S ... .61 66 ,BO ... -SO . _ . .80 80 tpeva LJmtied, Showcase Jay car Electronics . . JLB E:=ctron;cs, Showcase Lafacenter , . _ . Lichfield Electronics _ _ London Electron cs Co ege. Show-case Matrix Multimedia Ltd },[ QP El actio m cs , Shawcas e * . va.com . . * ,80 . . /ecrroo/cs.co, uk * z , , wv.w- ybetectfor vs con 80 . . jav. v, •s&ce.'Trecro vk „ 88 . . _ivv.vr.jL : zhuxlaE'.r.!smh&Qn&.tQjn ._*.__ . . . y- v.YSjiuamesiztlnm can) . . . . . . :AvAv.p£&AV*f£efgjA ...... . . . SWffcptrfZlLCQMi . * _ . * MV, W.D! CODS. Mm , * . . _ . yrAW4ifCQtBCfi.COm _ . _ -Hwv, quassreisotrontus-CGm . 7 7,7, :sp:ae-svfh\ < 3fs. cum •AYtVfJChlt-Etertro •; cs.CQ.iik v-w’j-ri totzi-ie cum . . . . * , za'ays. tt&ateds. co. uk . . . yy.w.sacflg.com * www ijsij- nstmmeris.com ... , . . .iiwi'/i v. ' l-hco:hlJ9.co.lA JVWWti r*i!)5_CGm . 81 16 .66 ...... .81 81 „ .81 43 ... 37. 81 . , , .29 .81 ...60,81 ... 61 81 . — * . .16 8e 61 81 Advertising space for the issue ol 18 October 2005 may be reserved not later than 20 September 2005 with Huson International Media - Cambridge House - Gogmore Lane - Chartsey . Surrey KT 1 6 9AP - England - Telephone 0 1 932 564 999 - Fax 01 932 5 649 98 — e-m ail: 1 -■ ~ r g h . 5 ;onr r n 10 w h om all corresp on ti e n ce . copy Enstmctions and artwork should be addressed. 84 e!=p,tcr electronics - 9/2005 Please supply the following. For PC8s. front pane! foils. EPROMs, PALs. GALs, microcontrollers and diskettes, state tfi- part number and description: for books, state the full tftie; for photocopies of articles, state full name of article and month and year of publication, PLEASE USE BLOCK CAPITALS. Description Price each Qty. Total Order Code cd-rom Elektor 2004 £ 16.25 GPS Receiver on USB e 62.05 OBD- 2 -Analyser: Kit of parts £ 52,50 DB 9 to OBD adapter cable e 27,55 Electrosmog Tester: Ready-built PCB e 50.00 Matching enclosure e 10.25 Pnc2s and Item descriptions subject to efiang i Subdota / Itie ptrtrtisfters reserve the nafrt to dtenge prices without prior notification. Prices arto flem descriptions P&P shown here supersede those fi» previous Issues. £. & O.L Total paid b;‘. ' CM only: issue number Name METHOD OF PAYMENT : see re. else before lic-ing is appropriate Note: cheques not made out in sterling must be increased by the equivalent of El 5.00 □ Bank draft □ Cheque raya t r tc E ektcr Erctramcs Pub sn fig | 1 Giro transfer roar account no. 3- 152 a SOI i □ Postal/money order Expiry da;e; P ease send this order form to " (see reverse for conditions} Elektor Electronics (Pubfishing) P.O. Box 130 Tunbridge Wells TN5 7WY ENGLAND Address Fast code TeL Ema, l Date - —2005 Signature ELC 3 Tel.: j-44) 10 1500 200 657 Fax; f+44) 0-580 200 616 6 nte : r. e t : v, v, „y . t- 3 ekto r-sEeG Ire n l cs.cq. u k ' U SA En d Cir. ■- d t - ■ ■ : i ■ : ■ 5 r ■ i\ i'Z'j: are not oz-egad M- :-Sr. S : s . ar 2 - ; ' : - f? - Ec Old Cole Ay Sound Lab ? O . E l i >. 6 75 . ?€*■= rb 3 r Q l 5 ii WH 03453-G37n. 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Our bankers are NAT WEST PLC, 1 St James’s Square, Wadhurst, East Sussex TN5 6BH. England. Our account number is 3512 5225 ; Sorting Code 50-22-15. IBAN code: GB4G NWB K6 022 15 3512 5225 BIG code: NWB KGB 2L COMPONENTS Components for projects appealing in Elektor Electronics are usually available from certain advertisers in this magazine, if difficulties in the supply of components are envisaged, a source will normally be advised in the article. Note, however, that the source^} green is (arei no: exclusive. TERMS OF BUSINESS Delivery Although every effort will be reads to dispatch your -order within 2-3 weeks from receipt of your instructions, .vs can nm guarantee this time scale for all orders. Returns faulty goods or goods sent re error may fcs retimed for replacement or refund, but not before obtaining our : : sml All goods returned should be packed securely in a padded bag or box. enclosing a covering letter stating the dispatch note number. If the yocres are returned because of a mistake on our pert, we will refund the return postage Damaged goods Claims for damaged goods must re received at our Tunbridge Wells office within 10-days (UK); 14-days (Europe) or 21-days (alt other countries}. Cancelled ord ers At! cancelled orders will be subject to a 10% handling charge with a minimum charge of £5 00* Patents Patent protection may exist in respect of circuits, devi- ces, components, and so on, described in out books and magazines. Bektor Bectromcs Publishing) acres not accept response tty or lability forfaiting to identify such patent or other protection. Copyright An drawings, photographs, articles, printed circuit Boards, programmed integrated Circuits, diskettes and software carriers published in our books and magazines {other than in third-party advertisements) are copyright and may cot be reproduced or transmitted in any form or ire any means, including photocopying and recording, in whole or in can. without the prior permis- sion of Efefctor Electronics (Publishing) in writing. Such written permission must also be obtained before any part of these publications is stored, in i retrieve 1 system of any nature. 'Jotvfithstanding the above, printed-circuit 3 cards may be produced for orivate and personal use without prior per- mission. 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