9 770268 45111 March 2005 £3.70 vnvw.eleirto^lecIromcs.cG.iik i I Ur i (10 111 I UtOUfit* jI//I /llVlilii IJI III /HHIUI aM tarn Programmable Crystal Oscillator Handy Opamp Tester Play Solitaire ■r / im K^ - iff u IJn m fr M| The leaders in PIC development AUTOMATION ♦ All you need to get started with PIC ♦ Industry standard/quality board ♦ Open the box and get coding ♦ Available with C compiler or_ use our PicScript to write programs using simple commands... NO ASSEMBLER, NO COMPILER, JUST WRITE ANDi RUN PicDev Board with PicScript £99.00 {plus p+p) This is a complete development suite for the novice or non programmer. It is shipped with: -Tl'f|§Sf . PicDev Board . PicShell and PicScript software . Breakout board • Cables • Example scripts Both items require order: • PC with serial port available * Power supply adapter ww wvpagraco,uk PicDev Board with C Compiler £165.00 (plus p+p) This is a complete development suite for the more advanced programmer. It is shipped with: • PicDev Board . PicShell and PicScript software . C compiler . Breakout board . Cables • Example scripts . 1CD1 sales%pagm.€QAik Tel: -44(0)1792 891927 Get Your FREE UK Pounds Sterling Priced Catalogue - all 424 pages! Just fill out the catalogue request form at www.jaycarefectronks.co.uk/cataloguf Check our website! * All of our 6,000+ products with search facilities. , * 128-bit secure on-line ordering - safe R secure. * Over 3,500 product datasheets R application notes, * And we're from Australia, so you can trust us! nOffilfllO r ttwJa^iHscfriifctcoiA Theremin Synthesiser Kit KC-5295 £ 13.05 The Theremin is a weird musical instrument that was invented early last century but is still used today The Beach Boys' classic hit "Good Vibrations" featured a Theremin. Kit includes a machined, silk-screened, and pre-driiled case, circuit board, all electronic components, and dear English instructions. This product is now available p re-built and fully tested - Cat. AM-402 S £ 27.2 5 \ ^ V Get the Video Quality You Paid For With Our Doctor Video Kit KC-539Q £ 29.00 Did you know that you are not getting the best picture from that Jy expensive movie -kz collection you paid good ^ money for? Copy p rote ctio n 1 J is put in place on videos and DVDs for a good reason, but ^ - ^ this robs you of the true high L-^"^ 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 dear English instructions. Note: Some SMD soldering required. Caution: During signal conditioning, this unit removes copyright protection. Piracy is a crime, ft Jaycar Electronics takes no responsibility for its potential for unlawful use. JUST ONE OF OUR MANY GREAT P RE- BUILT & TESTED CONSUMER PRODUCTS! Map Reading Made Easy! XC-0J75 £5. SO The digital map — distance calculator is truly a great device, | All you have to do is ; program the scale j of your map, then U L" roll the wheel tip | Hp along the intend- Ji i) © r ed route. It will \ . then display the \ ®i ACTUAL REAL 1 - , WORLD ^ DISTANCE in miles ’ for kilometres! on the LCD. ft is light and compact at around 125mm long. Performance Electronics for Cars Book ■ BS-5000 £ 6.35 .siectronJcs Australia's leading electronics ^ magazine, Silicon Chip Magazine, has developed a L - OB* 9 * range of projects for k A perfomiance cars. There are I 16 projects in total, ranging from devices for remapping fuel curves, to nitrous con- trailers, and more! The book includes all instructions, components lists, colour pictures, and circuit layouts. There are also chapters on engine management, advanced systems, DIV modifications, and more. Over 150 pages! A3 of the projects described are available in kit form, exclusively from Jaycar. Check out our website for all the details. Remote Control Extender Kit Mkll KC-SJ09 £6.70 If you have a source device such as a DVD player running to a TV in another room, or perhaps a HiFi system with speakers in the other end of your house, you probably get tired of walking to the other room just to change tracks or fast forward etc- This prolect effectively transfers the IR signal from your remote control and retransmits it in the other room! Kit includes case, circuit board, all electronic components, and dear English instructions. aaymr We Stock 50MHz Frequency Meter Kit with LCD Display KC-5369 £20,30 if you want a great value frequency meter, then this project is For you. it features Autoranging operation for ease of use, switching *«■*-*-" between its three ranges. High resolution of 0.1 Hz up to w f5QHz, 1 Hz between 150Hz and IfiMHz, and 10Hz above f 4 W 16M Hz. It can be powered by a 9V battery or wall adaptor Inot Included} and the case measures just 130 x 67 x 44mm. Kit Includes case, circuit board, electronic components, and dear English instructions. Log on to www.jaycarelectronics.co.uk/catalogue 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 Sitverwater Rd Silvervvater NSW 212B Sydney Australia Electronic Components Test & Measurement Equipment Power Products & Accessories Audio & Video Equipment & Computer & Telecoms Accessories Security & Surveillance Equipment DrDAQ i fe,' OfOAQ Output — Resistance 'J/.dltage Light level ■PMprzrrrrrr^p^:: . / \\ Temperature ^ > r Microphone ^ . x External sensors: Hi • Lowcost^^und e r £60 • Built in sensors^for light, temperature and sound O (level and waverorms) H • Use DrDAQ to capture fast signals • Outputs for control experiments \ • Supplied with both PicoScope (oscilloscope) and PicoLog (data logging) software \ For more information on DrDAQ, please visit picotech.com/drdaql 1 6 Scope and spectrum analyser functions A fraction of the cost.of benchtop scope Save multiple setups for ease of use Save, print and e-mail your traces FREE technical support for life j FREE software and upgrades f Automated measurements l AV&StS Virtual Instrument For more information on our scopes, please visit: g www. p i cotech .com/scope252 Tel: 01480 396395 Fax: 01480 396296 E-mail: saIes@picotech.com £> f 1 , (■ :* • ■ ft * AAMA MEETING Try :c picture tor yourself She bi-weekly general editorial meeting of this wonderful magazine, with its inherently international character. Everyone is Shere: France, England. Germany and She Netherlands, all seated around a large rectangular table structure. And m no particular order, of course. The lab Is also present in full strength. Everyone at ihe fable bos at bos! a masters in engineering. And then there's me. with a degree in 17^-century Dutch Literature from the University of Nijmegen (1978), chairing the meeting. 1 hardly need say that ihe risk of a Babylonian confusion of tongues is oil too real. And I can assure you that there are quite a few different "right answers '0 electronic questions. Or course. ( try to avoid oil of this by holding the Tear myself as much os pos- sible. Arte" oil I m the bass. Bui you can't keep ihe tension up all the time, so I like to relax She atmosphere by raising me discussion to a metaphysical level. For example., I might ask. Is there realty any difference between transistors and valves?', and then pour myself a cup of coffee - since nobody else does that for me, even though 1 m the International editor. And or course i know perfectly wd I that I'm not supposed fa ask such ques- tions, since the editorial staff is officially neutral. Out of the corner of my eye I see one at ihe designers uwolun- rarily cross his arms: body language for Tm toklng a stand'. On the other side ze outprinf of a text generated by one ct cur worthy employees is being vigorously shoved back and forth: body language for we don't agree on Inis'. Every once in a while I have to nudge things along a bit: 'Well, jusi say what you think!' (and hey presto see pages 2-5-27 in this very issue). Sometimes I manage to finish a whole cup of coffee before making another meaningful contribution to the dis- cussion. 'What matters he^e isn't technology or sound, but music. I still have the old vinyl IPs from Skip James and Jimmy Reed that I played on my very firs! turntable, when I had ic put a heavy coin on the arm to get any son of sound. And my son uses on MP3 player to listen to his music/ I can fee ; a shudder pass through the ranks at the audiophiles at the mention of ihe word 'MP3'. It reminds me of the official introduction of ihe CompactDisc (CD - Ed.), when a few Fellow journalists asked the Philips press spokesman how Philips hod the nerve to be responsible for eliminating everything below 10 Hertz and above 20,000 Hertz from the musical experience of audio enthusiasts. And they got on answer! In ihe resulting discussion, someone is bound fo come up with ihe idea of seeing where things stand with the development at Techniques to combat noise with sound. As I always say, a magazine like this puts itself together. Mat Heffeis, International Editor Volume 3 1 , Number 34 1 1 March 2005 ISSN G26S 4o 1 9 Ekktor Electronics aims at inspiring people to master electronics at any persona! level by presenting const met ion projects and spotting developments in electronics and infor- mation technology. - £‘“c — ni r ■ •: 5 iTOQ :: £ i : _ tr-=d Ee fee r L ! cL--o e'es BO. Box i90,Tunfc?id^ Vte&tNS 7W fcB^andL ld.;(k44}(fl)ISB0 2GG657, k* ■ -— : 5 SC 2006 16 , Em&i: Ei'j-i ; - - S 3 or-efet!ran :: -_~,n k. “= magaz're ias Ebfe *"'Z^ n=..\55££iTtS. DZi ETZ- t :“”' ih retal c -ji- ets. os'cn SwascrpEc^- 1:- - 2rr :■ s ih= ri I * .=- ; - a co-bte =£_■='£■- __ ■ f, Under the name Bekwr and Ehkti&sr, Ihe maga^sn Gsnnnsn and Duldt Together with ferdhsed edi i ” re re G 5 2 cc _ _ v as . 3 p;..r - i-rencr, "sirs r*i£iz -= = ““ i :_ International Editor r- - Editor: . = - r^~"£ ac i . Intarnatianal editorial staff: — ELggez 2 k. - 111— rj- Ge t i'iar.iz ' Ernst 1 G-.- - : -.ie3r T 7C2-" Design staff: 'Gzs /.ktovc-" “-llz _ : _5:r " : “ G esoeriL Fu Gii^- j — c j5rr:-=^ ■- - Editorial secretariat: ?•: : >:J3 Li: z - - - Graphic design DTP: G 2~ -2k <.ar= Ga G z z Managing Director . Publisher: IW Circulation Control: zk^ez i - * ::r~; : Subscriptions G z- -. v-i-e r: on S&v ze _zz LG : 4 G sbs -ttz G ' ~n " l , -G -.z “ 17 .5 “-G 2 l l~c -— : :e: : :=5 : sso 20tt * Errs - " 73 := _■ l.Gei ii~ : zerns l--l ^ - L-- c-- ' _ e 2 't=r . r : Head Office 2 . , = 0 Bc>. "2 ‘-,L-2 ”2-- 2 =-“• Tr 5 Niir£'i r 4: ttzbare -2. 4389444 Fax -5 -46 4372*6 Distrihutinn: ■ ^z_" :G l bzr-ccr P 22C UK Advertising h v3ch i 'e- : - 1 'Gg. C---:-~£e Ho-jsa Gog—-z~= _l-- O zGz-. 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Zzzr — Si,ir Li z- zez-^z cr ssz : ' " : « i>:— : : c- 7z z~± = _z i~~rg ;c rvG zi* : i--= zefrr - ="d :.: i^e 1 z cz. ■:= •!* ~ z:-e r :ep' r -^: z.z :ll.“z l-z ir ,7 e- ~-e 1 :■ r -Z z "L---T E^-=-=-se 10 i- - -ete-e s.z- :: zrz? t Segment b ,, 2005 Printed in the Nethertends 3/20&5 - E-lektor ebtlfcci'Ls 5 FXPERlEXCt: i J 1 1 B 'l f \ _ . — . [7] i p 4 if i | d'W f jT 1 1 | T> IlSM The High-End Preamp preamplifier published in the April & May 2004 issues naturally calls for a matching final amplifier in an identical housing. The sonic quality of the High-End Power Amp described in this article is outstanding, and its power output more than adequate for filling an average living room with an impressive sound image. Thanks to its robustness, Telefunken's legendary ELI 56 audio power pentode has found its woy into many professional amplifier units. Its attraction derives not just from its appealing shape, but also from its impressive audio characteristics. We there- fore bring you this classical circuit, updated using rug h -quality modern components. Informative Articles Regulars 25 Opinions on Valves 5 Foreword & Colophon 38 Anti- Noise 8 Mailbox 52 Delphi for Electronic Engineers (3) 44 News & New Products 78 Quizz'away 62 Altium FPGA LiveDesign Kit (review) 82 Readers Services 70 E-Online: Audio Tweaks 84 Sneak Preview 77 retronics: Edwin Audio Amplifier (1975) 84 Index of Advertisers Volume 31 March 2005 no. 34 1 M JiTi Hn V: jT*] | Noise has a serious impact on the environment as well as on human beings. Besides classical sound reduction techniques such os insu- lation, researchers are trying to attack the root of the problem using electronic means. They have already had some success. Modern circuits make ever more extensive use of FPGAs, Special software is required when designing with these devices. One of the companies that produces such software is Altium, who offer a cheap evaluation kit. Once the evaluation period has expired, the kit is still very useful as a development platform for your own designs! The right crystal controlled frequency at the right time: With this DIP outline oscillator there's no need to waif for a special crystal to be made up. You can program its fre- quency precisely using the RS232 port of your PC, Low phase noise is a feature that makes this PLL oscillator suitable for demanding RF applications also. Construction Projects 1 2 High- End Power Amp 28 ELI 56 Audio Power Amplifier 42 Remote Temperature Logger for PICT 8F Board 46 LPC2 1 Ox 'ARMee' Development Board i( 1 ) 56 Play Solitaire 66 Serially Programmable Crystal Oscillator 73 start here: Bidirectional S/PDIF Converter 74 kitchen table: Opamp Tester web technology allowing.,* our completely restyled website should be online by mid-February 2005. New features include Forum, Marketplace, News Service, Online Shop, secure payment options, article downloads.... check it out! mailbox II 3 TV Commercials Killer Dear Editor — your article on the J TV Commercials Killer' (July/Augusr 2004] was a very practical application. The problem with it, is that in my country, South Africa, the logo is usually at the bottom section of the screen. Is there any way of making it work for me? Maybe same hints on soft- ware modification. Thank you for such a great magazine. Chart Roux (South Africa) y^eUROSPQRT The same question has been asked by a number of other readers. As stated at the end of the article^ /he project was not tested or post- engineered by our in-house design staff. The authors contact details may be found at the end of the parts fist on page 27. Hopefully Mr. Schulze is able to help. Swiss Army Knife update Jim Spence kindly in formed that c software update is available ror his Swiss Army Knife project (Elekior Electronics September 20041 There is a new version of TCB (TB- 2-K } which enhances the existing TCB as follows: New comment symbol, allows source cade io be commented without being stored. Better error handling, indication line number where error occurred. Hex - handling of hex num- bers improved, numbers can now be either deci- mal or hex without chang- ing the operating mode. Example, a=&FE. LOADS - massive time sav- ing feature, LOADB will now load a TCB program with or without line num- bers, I2C - Full support for PC devices using software, no special processor needed, new |2C com- mands: CPOKE, CREEK, CPUT, CGET, CREAD & C WRITE, 241C256 - EEPROM support (LOAD & SAVE), enables programs to be saved and loaded thus eliminat- ing the need for a battery backed RAM, RUN - extended to allow run- ning programs in RAM space, when called from ROM space There is also a version that will work on the Elekior Electronics "Flash Microcontroller Starter Kit' — the same as above bu7 with automatic RAM detection switched off. The updates may be obtained from our website, see September 2004 items . Ather&emert Clarity Class-T amplifier Dear Jan — as you know we are selling kits of the Clarity Class-T Amplifier project Pune, September, October 2004; Ed.). Unfortunately we ran into supply problems with the STW38NB20 component, ST having advised us that it is no longer manufactured ond available to the retail trade. Can you suggest an alternative? Peter Geist (Geist Electronic/ Germany) Tort Gilberts, our audio designer replies: a possible alternative is IRF's type IRfdlNl 50, however it is housed in a TO220AB easel A quick comparison shows: Parameter IRF ST Unit k 41 38 A R K|0!i! 0.G45 0.065 il [max.} ^ECJ 200 180 W t*, 2S20 2800 pf ttyp.l T i 175 150 C C 0,75 m S CAV Gs 72 70 nC 150 200 V the sower value for Ur -5 is not a problem, the sicply voltage being smaller that 120 V Tripath also recommend this transistor tor use with meir TA3020., The replace- ment has not been tested yet in the Elekfor sabs. Parallel PIC Programmer Dear Editor — I would like to inform you about a PIC pro- grammer that's controlled over the parallel printer port and is compatible with Win 2000 and XP. It is found at www.oshansort.com. The signal wires used can be selected by the user. H» Sprenger (Germany) Thanks for the tip ! Crescendo ME and elec- troiytlcs in storage Dear Editor — it is my inten- tion to connect an Elekror Crescendo Millennium Edition ( J MF ) amplifier into a loud- speaker system with on impedance of about 2.5 ohms. Can you please Andre LaMothe's XGameStation LfAHN How tt=t 4nd desjg.v Your own video game coddle. 1 De^&i inspired Iqrtfie Atari 800/2600. Sinclair ZX Spectrum. V' ^ ~ ^ 4^. Apple II S Cccnmodwe W! /j# V sm ■INCLUDES; . // ‘ J> X * -. - ft" / Embedded Sjstensl ^ - J-tij taraitMXGS Micro 4 ff *Can[^Ft‘P' Srffirag Dgiefopment KHf WWW, X E3 AM ESTATl O N Fh: 3 25.736-2093 COM SiJPF=afiTiS>NURVE,NET 8 elekior elerfraraa - 3/20Q5 advise if that is possible with- out alterations to the amplifi- er electronics? Also, ! hove available a quantity of Philips 1 0 mF/63 V electrolytic copacitors that have been in storage for about 10 years (I think!). Can I use these com- ponents; it is possible to regenerate them, or should 1 bln them? Is there a way to extract the manufacturing date From the print on these devices? C* Krampe-Zadler (Germany) In theory. \ the lower impedance is just about acceptable if you assume that the amplifier does not supply more than 30 V at 2.5 Q (t.e. f 12 amps maximum). It Is therefore recommended to employ a mains tens former with a slightly lower secondary / voltage. Regarding your second ques- tion, having been in storage for such a long time , the electrolyf- ics are probably in need of being regenerated L This is be si done by applying the maximum device voltage (S3 volts) via a J- megohm resistor for some time, observing all relevant safety pre- cautions , In all probability, these devices will be usable . The man- ufacturing date can be gleaned from the date cods (DIN 41314 / 1 EC 60062). as follows: Year Code 1995 = F 1996 = H 1997 = j 1993 = K 1999 = L 2000 = M Month Code January - 1 February = 2 March - 3 April = 4 May - 5 June = 6 2001 - If July = 7 2002 - P August = 8 2003 " R September = 9 200=1 “S October = 10 2005 - 1 November - 1 1 2006 = U December = 1 2 2007 “V 2008 = W For example , a capacitor marked to' was manufactured in June 1 999 . OP-77 Replacement Dear jon — I ’m sorry the project I need to ask assis- tance with is a bit aged {'Compact AF Power Amplifier', EE May 1997). The problem is that the guy at my local electronics shop tells me the OP-77 opamp is no longer available, suggest- ing the LM3Q1 AP os an alter- native. Can you confirm this, please, or are there better alternatives? I also wonder if I can use the value 330 Q For R8 and R9, instead of the specified 340 Q which I am unable to obtain at such small quantities. E. Oeynhausen (Germany) The OP-77 may be replaced by any low-offset opamp. which pos- itively excludes the LM 301 PI Also , oe sure to select a type that's suit- able for operation at a supply voltage or ±13 Vi An excellent replacement for the venerable OP-77 is the OP177GP from Analog Devices, which is no coin - ■Lp cidence as it is actually an improved OF- 77. Another sug- gestion is the OPA 1 77GP from Texas Instruments (listed by, among others , Fern ell). If at all passible you should stick to the specified 340 ohms far R8 and R9. V/ith due regard fo tol- erance issues, the required value may be obtained by parallelling resistors tram the E24 series, or in reeky acute cases, the Ei2 series (do check the end result v/ith an accurate chmrneier); for example. 360 Q//6kl2 or 390 Q //2ktt7. Cleaning the Mains Dear Editor — I am looking for a circuit diagram of a good mains filter. Did you ever publish such a design and if so, when? Jan Verbeeck (Netherlands) it may not be obvious from the article title, but an excel- lent mains filter far home con- struction is included in 'Noise Suppression Filters' published in the November 2004 issue of Elektor Electronics. This article was the concluding part of our ClariTy 2x3 00- wart audio amplifier. Mains Filters must be built, installed and used in compliance with relevant safety guidelines. USB/t^C Interface (1) Dear Jan — Moving read your article in the December 2004 issue, I can not find conclusive evidence that the circuit, apart from its normal function, is also suitable for reading data on the PC bus, without omitting the P82B715PN component. My uncertainty is probably caused by the circuit symbol used for the component in the various drawings, and the fact rhot the examples only mention driving the outputs. Manuel Friedmann (Germany) Even if the circuit diagram does not show if explicitly, the PB2E7J 5PN is a bidirectional co mp on ent (see vvvnv. sem / co n - doctors, philips, com/p ip/P82B7 1 5 PN.html). Consequently, nothing changes when compared ro the circuit without the PB2B7 1 5PN. In c ids n to fly . co n troll in g de vices over the PC bus always requires a bidirection al interface . Also see ‘Corrections & Updates .. February 2005. MallBox Terms - Publi cat on of re a d e r s cc c g n - aen.es at she discretion of iha Eg [tor. -Viewpoints expressed by corres- pondents are not necessarily those of the Editor or Publisher. - Corr ss port cf enc e re s •, bs t/ sns’et ed o r -3 a -eg for ■ e v, □ th c • 3 ■ ■ y an d style. - When replying to Mailbox coire- scondence. please quote 'ssue number. - Ffease send your Mail Bax corre- spondence :g: editor @e lg_ kj a r -e SGimn cs. co.uk a r Bektor Electronics, The Editor. RO. Box 190. Tunbrrti gs We i 1 5 T ri 5 7 . 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BbihsjCcux 3srt;shfe, FG7 5AH Telsptane; 01169 6305-32 Fax: 01 1 89 83083 1 info@o2m8.com wvrw.o2m8.com Er^ ailrq Aquoru? tostjEil Sex-rtf £*£# fjs = ■ ^ J ‘ ’ Servicing Yqur Complete Prototype Needs O Prototypes a: a fraction of ins cost O Jbn: : og ond setup in c l - 'uded O Any contour O Fr4 1.6mm, 35^m Cu EURO CARD iwm + Tooting + PMopbts + VAT £ 29 . T S*Eri«g imy isry. ftwa O Industry standard quaSly O FMow tip smos nam 0 CAM f CAD consulting ~ ' iit. §£s 0SOO-3® Simply send ym fiks end order OHtiHt -POOL COM m j i(| | ■ r j Are you passionate about your m electronics! | Do you love building kit, and making things work! ^ Do you want to build a career, getting paid for doing what you enjoy! Yes to all of these? Then plug into your potential - launch or upgrade your qualifications in Electronics, by studying at Derby BSc Electronics BSc Electrical & Electronic Engineering Also Foundation Year, and HNC/HND Electrical & Electronic Engineering ■ For people who love electro flics, caught by people who love electronics ■ Part-time and full-time study modes available ■ Ideal both for the school leaver, and the mature learner m Easy upgrades from HNC to HND to BSc (Honours) ■ Final Year options give specialist training in current hot topics, like digital signal processing, embedded systems, EMC, or power electronics For further details view httpi/verdgo.der byac.uk/ and email or phone: Dr Amar Bousbaine. a.bousbaine@derby.ac.uk teLOJ332 591760 ORTfm Witmshursc cj.v/i1mshurst@derbyac,uk tel: 01 332 591350, University of Derby, Kedleston Road, Derby. DE22 1GB. UK P iu 9 * ns UNIVERSITY to your potential of DERBY 3/2W5-$kVter eketfews n Ton Giesberts J 7 High-End P ^ Preamp preamplifier published in the April & May 2004 issues naturally calls for a matching final amplifier in an identical housing. Due to the restricted size of the enclosure, the output power of this final amplifier is somewhat on the modest side, but the quality is outstanding - and it is more than adequate for filling an average living room with an impressive sound image. G±3I9@ - T5 Figure L Block diagram of the High-End Power Amplifier , ; vv/u'cfi rs based on previous Elektor Electronics designs. The Audio Link amplifier, published a year ago, was well received by audio enthusiasts due to its very convenient user interface and high-quality, no- nonsense signal processing A match- ing final amplifier must naturally have the same level of quality, and here we have made an extra effort to achieve this result. Our desire to use an identi- cal enclosure meant that there wasn't all that much space available, and the maximum output power of a final amplifier largely depends on its size. The dimensions of the heat sinks and transformers are particularly rest noted by the size of the enclosure. We man- aged to achieve a bit less than 50 watts into 4 ohms, using 80-VA toroidal transformers. This amplifier is thus primarily suitable for people who like to listen to music at a ‘civilised’ volume and are very demanding with regard to reproduc- tion quality. As the output power is distinctly less than what many of our previous (dis- crete) final amplifiers can provide, we added an accurate overdrive Indicator to this design. It compares the input and output signals of the final amplifier and fights up an LED if the difference is too large. This enables the listener to keep a good eye on the output drive level. Output stage Readers who have paid attention the schematic diagrams of our final ampli- fiers during recent years will see a lot of familiar features in the present design. There aren't any real surprises, and the sound quality is determined more by the choice of transistors and the circuit board layout than by the cir- cuit design. As you can see from the block dia- gram in Figure 1, each channel of the amplifier essentially consists of two differential amplifiers and an emitter follower, but with a fully sy mm etrical design. There is also an integrator that eliminates any DC offset voltage at the output. The input stage differential amplifier (Figure 2) consists of two complemen- tary dual transistors (Tla/Tlh and T2a/T2b) from Toshiba. It is followed by a second set of differential ampli- fiers (T7/T8 and T9/T10}, which pro- vide most of the gain. The combination of T7 and T9 also forms a push-pull amplifier that can supply more than enough current to drive the emitter-fol- lower output stage. The operating points of these differential amplifiers are determined entirely by the operat- ing points of T1 and T2. The currents through the differential transistors in the second stage of the amplifier are determined by R2Q-R22 or R23-R2S and the voltage across R7/R8 or R10/H11, respectively. The voltages across the collector resistors of the input pairs are in turn determined by const ant -current sources T3 and T4. As can clearly be seen, all of the oper- ating points in the amplifier are directly dependent on th.es e two cur- rent sources, so we gave particular attention to their design. The reference voltages for the current sources are provided by fiat LEDs, which in turn are operated at reasonably constant currents provided by a pair of simple JFET current sources. As a result, the current sources built around T3 and T4 are practically immune to power-sup - ply ripple and supply voltage fluctua- tions, Unfortunately JFETh have a rather large tolerance range, so yon should measure the voltages at the points shown on the schematic dia- gram and compare them with the indi- cated values. A deviation of more than 20: i: is not acceptable. The power output stages are wired as emitter followers using a standard design with two complementary sets of transistors in Darlington configura- tion (T12/T14 and T13/T15). Resistors R26 and R27 are placed at the inputs of the emitter followers to linearise the input impedance of the current ampli- fication stage and reduce the effects of various parasitic capacitances. Although this reduces the op an -loop gain, it also considerably increases the bandwidth. This allows less negative feedback to be used, which from an audiophile perspective can be regarded as better for reproduction quality. Til is used to set the quiescent cur- rent. Here we use the same type of transistor as the NPN driver *T12). Tins makes assembly easier because these transistors have a plastic package that can be fitted to the heat sink without using an insulator, which is also true of T13. The quiescent current bias tran- sistor is located on the circuit board between die two output-stage transis- tors (T14 and T15}, which do have to be fitted with mica insulating washers, in order to achieve maximum thermal coupling. Driver transistors T12 and T13 are located on either side of this set of three transistors. The quiescent current of the output transistors is set to 100 mA, which is sufficient. Integrator IC1 compensates for the input bias current, as well as any off- 3/2QQ5-c*VfGf ckdmmts 13 Figure 2. Coreful component selection enables this design io achieve significantly better results than previous models. sets that may arise due to inequalities in the various DC settings, by injecting a current into the input of the amplifier. The bias current is primarily due to din ferences in the amplification factors of the complementary dual transistors and the currents from the two current sources, as well as imbalances in the transistors of the following stages (dif- ferences in amplification factors and base-emitter voltages). A bias current of approximately 8 uA can be compen- sated using the indicated component values. R48 and C20 determine the integration time constant, and C19 decouples any effect from IC1 (except for bias current correction). R1 and Cl at the input of the amplifier form a low-pass filter that prevents the amplifier from being overdriven if excessively steep signal edges are present at the input. To keep the result- ing offset voltage small, input resistor R2 has a lower value than usual (10 kU in this case). The input sensitivity of this final amplifier has also been made relatively low to reduce the likelihood of overdriving. Its gain is thus set to approximately 10.5 using R17 and R18 (but don’t forget the effect of Rl). For IC 1 to do its job properly, the input must be AC coupled. With the value chosen for the input resistor, the capacitance necessary io yield a suf- ficiently low roli’Off frequency can only be provided by a capacitor with rather large dimensions, so we decided to put it on the printed circuit board for the overdrive indicator cir- cuit. That allows the circuit board for the final amplifier to remain relatively small and increases the distance between the mains transformers and the amplifier circuit board. An addi- tional benefit is that the overdrive indicator can directly access the input signal after the input capacitor, which eliminates the need for an extra tap. The frequency compensation for the amplifier, which largely determines its open-loop characteristics, is provided by C2/R9 and C3/R12. HF decoupling is provided by the C1G/R19 network. The amplifier output is switched by a 16- A relay The type specified in the components list has an industry- stan- dard pinout and can be replaced by other equivalent types. To protect the loudspeakers against output offset voltage transients that may occur when the mains voltage is switched on, a switch- on delay is pro- vided for the output relay. The delay time is approximately 6-7 seconds. The state of the relay depends on the supply voltage for the final amplifier, rather than the transformer voltage. It the supply voltage drops below 17 V, MOSFET T18 de-energises the relay. 14 cis'doi elecfrunks - 3/2005 +1SVL Figure 3 . The siereo overdrive indicator constantly compares the input and output signals of the final amplifier and shows whether the difference is too large. The input capacitors for the amplifier hoards are also located here . The MGSFET starts to conduct when its gate voltage is approximately 2.5 V The threshold value can vary from one FET to the next, so the delay time can also vary. The gate is connected directly to the supply voltage via volt- age divider R42-R44. Diode D12 pre- vents C18 from holding the MGSFET in the ‘on state when the supply voltage drops, and D13 ensures that C 18 dis- charges if the supply voltage drops below half its normal value. This avoids excessive reduction in the delay time if ihe amplifier is switched on too quickly after being switched off Toe relay coil is connected to the sup- ply voltage via R45. so a relay with a lower coil voltage can be used by changing the value of R45. Re sure to use a resistor with an adequate power rating. The DC protection circuit is also con- pled to the switch-on delay circuit. It de-energises the relay by quickly dis- charging G 18 in the switch- on delay circuit. If a positive DC voltage is pres- ent, T16 will conduct and discharge capacitor CIS via R4G if the voltage at the amplifier output is greater than - 1.5 V. If an excessively large negative voltage is present at the output H T17 will conduct due to the negative volt- age on its emitter. In this case, the dis- charge current from CIS must flow through R37 and R3S. The resistance values of voltage divider R42-R44 also determines the values of R37-R39. The latter values must be kept relatively low, since other wise the threshold for detecting a negative DC voltage on the amplifier output would be too great. It is approximately -3.5 V with 100 -kH resistors This means that the circuit is somewhat less sensitive to negative DC voltages than to positive DC volt- ages, but that does not have any prac- tical consequences. Overdrive indicator As the output power of this amplifier is rather modest by contemporary stan- dards, it s quite possible for it to be overdriven during loud music pas- sages, which will re suit in clipping. For this reason, a reliable LED indicator circuit has been added to the design to indicate overdrive conditions. Toe indi- cator circuit (Figure 3) constantly com- pares the output signal with the input signal and generates a warning if they do not match. Apart from having greater amplitude, the output signal from the amplifier should have the same phase and frequency character- istics as the input signal. The signals are compared by attenuat- ing the output signal and amplifying the input signal. The input signal amplifier built around IClb (or IC3b for the other channel, which is not further described here) simulates the transfer 15 3. 2005 - dAtor drcir cries 01... D4 = MBRlCUQG C=, CS, C6. C9 = t = “v_ V R1 ||03 i-C D-^HNkH POWER #- -T I cs C5 H 05 C7 toon g — i | 1 , Jc eg Ida i i IDOn <£> DS...09 = MBR10100 C15.C1D 013 Cl9 = 6*«k r'35V R2 SkB 4t Die POAEP C 15 l I CIS 4 cia tcis t CO i£H?n * K4 020 iCOn 9*3193-13 Figure 4 . The power supply uses Schotfky diodes for low voltage losses and has a buffer capacity of 2 ■ / 3 .000 iiF per channel. characteristics of the final amplifier as ’.veil as possible using simple means. For instance, RC network R3/C2 has approximately the same time constant as the low-pass filter at the input of the final amplifier (R1//R2 and Cl), R3 and C4 are reserved for unusual input con- figurations in other applications and are not used here. The network formed by C4 and R7 does not have much effect here, but it is included for the sake of completeness, IC1 is a fast dual opamp (type AD827). Here ICla is configured as a difference amplifier that compares the two sig- nals at its inputs. R8 and R9 attenuate the loudspeaker signal by a factor of two (10,5 2). This means that IClb * 04-1:1 - t-6 Figure 5. An auxiliary circuit for the mains fuses and some terminal blocks for connecting the transformers and mains switch. only has to provide a gain of 3.5 (10.5 * 2 1.5). The gain of ICla can be adjusted using Pi to compensate for variations in component values. In the- ory, PI should he set to 210 Q. The output signal from IC la is fed to the input of IC2, a dual comparator that is used here as a window com- parator, The threshold levels are ^G.5 V and -0.5 V, which means that the output voltage must diner from the expected value by more than 1 V (10.5 times the input voltage) to generate an warning signal. It hardly needs saying that a large difference is most likely a sign of clipping, which occurs when the amplifier is overdriven. Reducing the threshold levels would excessively increase the sensitivity of the circuit to noise and other forms of HF interfer- ence, so the LED would tend to light up before the amplifier was actually being overdriven. The combined open- collector outputs of the comparators charge capacitor C5. Here R15 provides current limiting. The voltage on C5 is used to cause LED D 1 to shine quite visibly even if overdrive only occurs during short peaks. After the comparator outputs have returned to the high-impedance state, the LED will continue to be sup- plied with current via const ant-current source TL This causes rhe energy stored in the capacitor to be used as effectively as possible, so the LED will shine with constant brightness as long as possible. The current through the JFET is set to approximately 2 mA by R14. Using a low LED current allows a fairly small capacitor to be used for C5, which saves space. However, ibis requires using a low-current LED that shines brightly with a current of 2 mA (an example is given in the compo- nents list). The input ground is kept strictly sepa- rate from the remainder of the circuit on the circuit board, in order to avoid ground loops. The input signal ground is connected to a star point on the amplifier circuit board. The input sig- nal and the ground connection of the input socket on the indicator board go from here to the amplifier board. Resis- tor R1 ensures that the input terminal of Cl is always connected to ground. R2 is necessary to provide the bias cur- rent for the input of IC lb. As R2 is con- nected in parallel with the input, we decided to tie it to the inpur ground of the amplifier board. Drawing the bias current for IClb from that source does not have any negative effects. The advantage of placing the input capaci- tor on the indicator board is that it allows the signals to be compared from DC to more than 20 kHz. This avoids any measurement errors due to the lower roll-off frequency. The supply voltage for the indicator cir- cuit is taken from the main power supply and stabilised using Zener diodes, since the value is not critical. Allowance has been made for a fairly high load on die supply and associated voltage slumps. For this reason, the Zeners are operated at relatively high currents, which means that the associated series resistors (R16, R17 t R33 and R34) must be 1-watt types. To save space, we selected espe- cially small types (Vishay BCcompo- nents PR01 series). Power supply A separate printed circuit board has been designed for the power supply (Figure 4), It just fits into the enclosure between the transformers. The power supply design is quite conventional, with a standard 8Q-VA toroidal trans- former, rectifier, and electrolytic smoothing capacitors for each channel. To make it easier to connect the trans- formers, we also designed a separate circuit board with three terminal blocks and two fuses (Figure 5) to allow the primary leads of the two transformers for a stereo amplifier to be properly con- nected and fitted. The secondary leads 16 ckfclnr Eiirtronics - 3/2005 Measured performance Besides these numerical results, we also recorded several plate that give a bit more insight into ihe quality and character or the amplifier. Plot A shows several measurements of harmonic distortion and noise with a bandwidth of 80 kHz, Two measurements were made at a power of 1 W with 8-12 and 4-0 loads, one measurement was mode at 50% maximum power level with an 8-Q loaa. and tne final measurement was mode with the same output voltage and a 4-Q load. The four curves ore very close togeth- er, which suggests that the amplifier is practically insensitive fo the load impedonce. Plat B shows distortion plus noise os □ function of output amplitude with an 8 O bod. At power levels up to 0.5 W the meas- ured f alue is determined by the very low noise level. Above this level the distortion increases gradually until approximately 21 W. At this point the amplifier deports from linear operation and enters a soft-clipping region. The soft-clipping region extends over roughly the final ten watts or the amplifier's output power for the Final 3.5 volts of its maximum output voltage) . This meas- urement was made using a 14cHz signal and a bandwidth of 20 kHz to make the effect of the harmonic components more visi- ble. Plot C shows a Fourier analysis of a 1-kHz signal at 1 W vdth on 8-Q bad* Here the harmonic distortion is dominated by the second harmonic, 'which lies at a level of approximately -104 dB. t his mokes it negligible. The same holds true for the effect of the magnetic field of the mains transformer, which is responsible for the 50 Hz component in the plot* This level corresponds to o power of only 10 pW* 3/2005 - deleicr electro n-b 17 of the trails formers are connected to the printed circuit hoard holding the smoothing capacitors and rectifier diodes. The electrolytic smoothing capacitors are quite ordinary types (6 BOO pF; 35 V) with radial leads and a diameter or 25 mm {there's no room in the enclosure for anything larger). The type used here has a quite low profile (only 30 mm), so there’s more than enough room in height. Due to the relatively low supply volt age , we used Schottky rectifiers made by ON Semiconductor. They are rated at 100 V / 20 A peak. Tire forward voltage drop per diode is only 0.5 V at 3.5 A. Three-way circuit-board terminal blocks are used for all external leads to simplify fitting the wiring and any nec- essary maintenance. There are also two LEDs on the circuit hoard lone per channel) to serve as supply voltage indicators. If the mains switch does not have a pilot lamp (on the front panel), they should be used instead. €onstruction Toe compact, double-sided printed cir- cuit board for the amplifier is shown in Figure 6, We don't often use double- sided boards for Eiektor Electronics final amplifiers, hut here this provides definite advantages and yields shorter signal paths between the components. Fitting the components to the board should not pose any particular difficul- ties (no SMDs this time), but you do have to work accurately. All of the components are very close together, which means you have to fit them tidily, use components with the proper dimensions, and take care when fitting them (correct polarity and value). There are a few derails that deserve special mention, LEDs D9 and DID must be fitted with theii flat sides in contact with T3 and T4 for good ther- mal coupling, in order to make the cur- rent sources temperature-independent. Transistors T7-T10 are screwed to a common heat sink. Use a piece of alu- minium for this, with dimensions of 85 x 33 mm (the same as the circuit board) and a thickness of 1.5-2 mm. The height is such that the cop panel of the enclosure can just be fit red in place. Use ceramic insulators (Fischer type AOS 220) for all four transistors, and screw them in place in facing pairs. Use the specified low-inductance resis- tors for R34 and R35, since otherwise there s a very good chance that the amplifier will be unstable. Coil LI can be made by winding 1 . 5 -mm COMPONENTS LIST Amplifier beard (040198-1) Resistors: R 1 , R 1 7 , R 1 9 - 4700 R2 - 1 0k a R3-R6 = 330 R7,R8,R]0,Rl 1 - 8200 R9,R1 2 = 150 R1 3,R15 r R40 = lkft R] 4,R1 6 = 2700 R1 8,R26,R27 = 4kQ7 R20 R23 ,R32,R33 - 220 R2LR22,R24,R25 - 100 R2B = 5600 R29 = i 200 R30.R31.R45 = la R34,R35 = 0022 MPC71 R36 = 202, 1W (e.q. Farnd! # 306- 040 8| R37-R39 - 1 COkO R4 1 - 1QMO R42.R48 - 3300 R43 R44,R46 r R47 = I MO P 1 = 2500 preset Capacitors: Cl - InF C2„C3 - 2nF2 C4.C7 r Cn i C]2 J C14 = lOO.^F C5,C8,C 1 3 C15 = 3300pF 35 . radial !ead pilch 7.5mm, diam, I 8mm max. [e.g. FarneSf # 303- 6467) 18 dehor akefredu - 3j 2095 Figure 6 . The mono amplifier circuit board is double- sided and through' hole plated fo keep the signal paths betv/een the components short and avoid wire bridges. diameter enamelled copper wire on a 10-mm drill bit (the smooth part, of course). Leave fairly generous leads and scrape them nicely clean with a small knife. Then insert R36 in the coil, bend over its leads and fit the assembly to the circuit board. Then solder the coil and resistor in place. Cut off the free ends of the coil leads after they are soldered, but not too close to the circuit board. Don't solder the driver transistors, out- put transistors or quiescent -current transistor to the circuit board just yet. The leads of these transistors must first bent to the right spacing, so they can rest properly on the heat sink with- out any mechanic at strain after being fitted. That is described in detail under 'Final assembly \ Next comes the indicator circuit board (Figure 7). It doesn’t involve much out of the ordinary. R16, R17. R33 and R34 must be fitted a bit above the board and bent slightly away from the decou- pling capacitors, since they must dis- sipate a fair amount of heat. If you wish, you can use a multimeter to adjust presets PI and P2 to 210 O before soldering them to the board (refer to “Alignment 7 at the end of the article). For Cl and C2, be sure to buy a type that has the right dimensions to fit on the circuit board. The power supply board shown in Fig- ure 8 can be quickly put together, but here again you must be sure to use capacitors with the right dimensions and the proper type of Schotiky diode. Don't forget the wire bridges under and between D2/D3 and D7/D8* C6.C9.C19 = 47GnF CIO = 15oF Cl 6,CI7 = 47uF 25V, radial Cl 8 - lOuF 63V, radio! C20 = 2gF2 MKT, lead pitch 5mm or 7.5mm Inductors: LI = 8 rums 1.5-mm dsam. [SWG30J enamelled copper wire Inside diam. 10mm Semiconductors: D]-D4,D1 1 -D 1 3 = TN4148 D5-D8 = Zener diode, 4V7, 0W5 D9.D1 0 - LED, flat, red D 1 4 D 1 ^ - Zener diode, 5.6V, 0.5W 1 1 = 25C3381 BL [Toshiba Huljzer, Segar-electronics} T2 = 2SA1349BL (Toshiba, Huijzer, Segor-elecfranics] 13 , 17 , IS = 2SA1209 [Sanyo, Forneli # 410-3841) F4j9,i 10 = 25C291 1 [Sanyo, Parnell #410-3853] T5J6 = BF245A II 1 T12 = 2SC517T [Toshiba, Huljzer, Segar-efedranics) T 1 3 = 25A1930 [Toshiba, Huijzer, Seg o r-e ! ec Iron i e s) 114 = 25C5359 (Toshiba, Huljzer, Seg Dr-electronics] T15 = 25A1 987 {Toshiba, Huijzer, Seqor-elecEronFcs) T16T17 = BC547B T1 8 = B3170 1C 1 = OPA177GP [Texas Instruments/Burr- Brov. n, e.g. Fame i # 205-023) Miscellaneous: K1-K5 = PCB-mounr spade JFaston) terminal, vertical, 2 pins RE I = PCB relay 24V, 1 6A, 1 1 GOO (e.g. Omran G2R-1-24 VDC) Heatsink, 1.25 K/W eg, [Fischer 5K41 1, height 50mm] Ceramic insulators far T7-T1 0 (Fischer AOS220) Mica insulating washers far T14 & T1 5 (e.g. Conrad Electronics # 1 89049) Enclosure; e.g. UC-202H/5W ( Mo n a co r/ Mo n □ r c h ] 3/20 D5 - els her eliitrcnks 19 COMPONENTS LIST Indicator beard |04G 1 98-2) Resistors: R] ,R1 8 = 1M LI R2R1 9 = lOOkD R3,R20 *= IkQ R4.R21 = OH (wire bridge) R5 R22 - lkQ69 R6.R23 = 4kQ75 R7,R1 1 R1 2,R24,R28,R29 - 470.Q R8,R25 - 2GknO R9,R26 = 10LQ0 R10,Ri3,R27,R3G - I5kfl R14,R3I - 2700 R15.R32 = 1500 R1 6,R1 7R33..R34 = 2200. 1WFR01 (Vishay BCcomponents, Parnell # 337-778) PI r P2 = 5000 preset Capacitors: Cl ,02 = 1 OjxF 63V MKT, lead pitch 2 2. 5/27.5 mm W x l = 11 >r 31mm max* (e.a* Parnell # 400-2015] C2X13 = 470pF C3 C14 = nor hired C4,Ci 5 = 15pF C5 r Cl 6 = 22tiF 40V, radio! C6-C9.O7-C20 = lOOnF 00,0 1 ,C2 1 C22 = 470pF 25V. radial Semiconductors: Di ,D2 - LED, red, low-current, 3mm, 2Gmcd at 2mA [Kingbright L- 934L5RD, Far n el! # 627 - 075 } 03-06 = Zener diede. 15V 1. 3 W T1 J2 - BF245A 10 ,IC3 = AD827JN (Analog Devices, Fame!!# 24^165) 1C2JC4 = LM319N Miscellaneous: K1 .K2 = cinch socket, PCS mount (eg. Manacor T-709G) Figure 7, The indicator circuit board also holds the input capacitors (C 1 and Cl 2) for the amplifier boards . COMPONENTS LIST power supply board (040198-3] Resistors: R1,R2 - 6kQ8 Capacitors; C 1 -C4 ,C 1 1-0 4 = 47nF ceramic, lead pitch 5mm C5,C6,C8 C9,C 1 5 , 06,0 8,C 19 = 6800uF 35 V, diom. 25mm. lead pitch 1 Omm (Parnell # 652-090] C7,0 0,0 7,C2Q = lOOnF MKT, lead pitch 5mm or 7.5 mm Semiconductors: 01-04,06-09 = Schottky rectifier, IGA, 1 00V TO-220AC package [e.g. ON Semiconductor MBR 1 0100, Parnell # 878-443} 05,010 = LED, red, low-current Miscellaneous: K1-K4 = 3 -way PCB terminal black lead pitch 5mm 20 deleter dsrtrrjc - 3/2 005 Finally there is the small circuit board with the mains fuses and ter min al blocks for distributing the mains volt- age (Figure 9). Of course, this board isn't essentia], but it makes the wiring quite a bit easier (and safer)). Final assembly As we already mentioned, the ampli- fier uses the same type of enclosure as the 'High-End preamp* preamp. That r s why we went to so much trouble to keep everything as compact as possi- ble. For the heat sinks, we looked for types that were not too long and still had sufficiently low thermal resistance. We finally settled on the Fisher SK411, which with its modest dimensions of 116.5 x 50 x 50 nun leaves enough space between the heat s inks r 0 fit the loudspeaker terminals (using relatively small types) and the input connectors. To maximise the available space, we milled a 1.7-mm rebate around the edge of the heat sinks, so their bases fit nicely between the two fastening rails. This also causes the edges of the heat sinks to be flush with the side faces of the enclosure. Each heat sink is secured by four M3 screws fitted through the heat sink and the rails. The head of an M3 screw will fit between the cooling fins of this type of heat sink. In principle, the output tran- sistors could be attached the same way. This would make assembly a bit easier, but it would also make the cir- cuit board unnecessarily large. A small 1.5 -mm aluminium plate can be fitted between the two heat sinks (measure carefully] to hold the speaker terminals and input connectors. The original rear panel of the enclosure is not used. There's actually nor any room left for the mains cable (and certainly not for an IEC mains inlet). In our prototype, we used a sturdy mains cable and strain relief routed through the bottom plate next to the circuit board with the fuses. In this case, the enclosure must rest on high feet that are high enough to prevent the mains cable from being pinched off Fit the mains transformers as dose as possible to the front panel. The mains switch and LEDs from the overdrive indicator can then be fitted on either side of the fuse circuit board and the transformers. Attach the fuse circuit board to the base plate using 10-mm standoff sleeves with nylon screws and nuts (the terminal blocks we used are partially open at the rear). This ensures Class-II isolation (be sure to read the instructions on the ‘Safety Guidelines' page). In general, always pay careful attention to the isolation of components carrying mains voltage. Maintain a dis- tance of at least G mm from parts that can be touched by users. Figure 8. The power supply circuit board holds o total of eight electrolytic capacitors to power two amplifier boards , For each power supply terminal, insen the supply leads for the amplifier boards and indicator board together in the appropriate terminal blocks. Heavy wire with, a cross-sectional area of 2.5 mm 2 must be used for the amplifier boards, but thin flexible wire is ade- quate for the overdrive indicator board. Make the supply leads for the amplifier boards as short and direct as possible. We crimped tab connectors to the ends of the leads, but you can also solder them directly to the boards. Connect the speaker outputs on the circuit boards to the output sockets in the same manner. At the sockets, we sim- ply fitted wire lugs to the ends of the wares, which avoids the contact resist- ance of an additional plug. The power supply leads for the overdrive indicator board can be simply soldered in place. Fit the overdrive indicator board in the middle between the amplifier hoards. The input sockets will then be almost 3/2005 - eE-ktor rktlroniti 21 COMPONENTS LIST Fuse board (040198-4] Miscellaneous: K1-K3 = 2 -way PCB terminal bbck. lead pirch 7.5 mm H..F2 = fuss,, 4C0mAT (lime lag), with PCS mount holder Figure 9. A small auxiliary circuit board for the fuses and mains connections. flush vith the rear panel. Naturally, it will take a bit of measuring and fitting to get the holes for the connectors in the right places. The manner in which the heat sinks are attached causes the mounting sur- face to be approximately 6 mm away from the edge of the circuit board, assuming that the amplifier circuit boards are attached directly to the rails. This means that the leads of the trails is lots must be bent twice allow them to be positioned correctly with- out creating permanent mechanical stresses in the transistors. For the large 22 dsktc-i ikdraria -3 2005 PCBs: Required for o stereo amplifier [see Readers Services page): 2 ea_ order code 040 1 98- 1 1 ea. order code 040198-2 1 ea. order code 040198-3 1 ea. order code 040198-4 output- transistors, the first bend will have to be somewhat closer to the plastic package than what is intended (in the wide part), since otherwise the leads will touch the rails or won’t fit at all. Another possibility, which has the disadvantage that it weakens the structure, is to hie away enough metal at the appropriate locations to provide adequate clearance. We intentionally rejected this option. Once you have taken care of this detail and the transistors can easily be placed Qat against the heat sink with their leads passing freely through the holes in the circuit board, you can. mark the locations of the mounting holes on the back of the heat sink. Naturally, you should do this before the transis- tors have been soldered to the circuit board, but after the final holes for fas- tening the amplifier circuit boards have been made in the bottom plate. Once the output transistors and their drivers have been fitted to the heat sink and soldered to the circuit boards, the bot- tom plate can be removed quite easily. Be sure to not exert too much force on the leads of the transistors when the boards are suspended this way. Power transistors T14 and T15 must be fitted to the heat sink using insulators {mica washers), while the other three transistors (Til, T12 and T13) can be screwed directly to the heat sink. Be sure to use thermal paste with all of the transistors. After you have made all the mounting holes for the remaining circuit boards, transformers, mains switch and LEDs (in the front panel) and ventilation holes in the enclosure, you can screw every- thing else in place and fit the w irin g Use well-screened audio cable to con- nect the inputs of the amplifier boards to the terminals near the input sockets on the overdrive indicator board. Use the two ground terminals next to the input sockets to connect the enclosure ■ i , i 1 y - y m _ Figure 1 0. The wiring diagram shows the proper way to connect everything together inside the end 05 ure r 3 50Q5 -sViiurikdrsdii 23 Transistor selection Toshiba iype 2SC338] and 25A134 duo! transistors are used for the differential amplifiers in the input stage. These transistors moy be difficult to obtain, but they are practically the only good complementary dual transistors still commercially available. We selected Sanyo type 2SC291 1 and 2SA12G9 transistors for the differential amplifiers in the voltage gain stage. These tran- sistors come in a TOri 26 package and have outstanding linearity combined with low output capacitance (3 pf and 4 pF, respectively], and they can hoodie up ro 160 V. The maximum dissipation is 10 W (4 W oi 100 C), and the maximum rated collector current is 200 mA for 1 second or 1 40 mA continuous. The maximum allov/able emitter-base valiage is only 5 V, so a pair of 4,7 V Zener diodes are connected back to back between the outputs of each of the input differentia] amplifiers (D5-D8). The dual transistors have similar restrictions, so two back-to-back diodes are placed between the inputs of each of the differential amplifiers (D1-D4). Matching the respective pairs of transistors [NPN-NPN and NPN-PNP) will certainly help improve the quality of the amplifier so you should pay attention to the parameter classification (GR/SL. R/S/T/, and R/OJ when purchasing these components. For the output transistors and drivers we chose some old friends, namely the transistors used in the Titon 2000 amplifier (Elektor Electronics, February-May 1999). These output transistors have a relatively constant hp? up to 5 A, so they do themselves proud in this amplifier. They can handle a maximum continuous current of 15 A, which in practice means that ihe amplifier can be used with load impedances os low as i .5 il , For integrator !C1 we selected an OPA177, which has a very law offset voltage (100 uV between -40 : C and ~85 = C). This opamp has a maximum bias current of ± 6 nA, which makes a small contribution to the residual offset at the output of the ampli- fier (=2 mV maximum, equal to 6 nA x 330 kQ). We chose a MOSFET for II 8 in the protection circuit so that voltage divider R43/R44 could have a high impedance. This allows the capacitance of CIS to be kept relatively smalt which has two benefits: the dimensions of CIS con be kepi modest, and ihe DC protection circuit does not have to draw so much current From Cl 8, to the grounds of the two channels. This avoids creating any ground loops. The measurement inputs for the ampli- fier output signals are located in the middle of the overdrive indicator board. The easiest way to connect them is io use thin, flexible wire to con- nect them to the output sockets. For the sake of clarity, the complete wiring diagram of the final amplifier is shown in Figure 10. One of the cover panels for the enclo- sure is solid, while the other one has punched perforations. To keep the assembly sturdy, we decided to use the solid panel for the bottom panel and the ripen panel for the top panel, which provides continuous ventilation for the enclosure. However, we recom- mend making additional ventilation holes in the bottom panel near the amplifier circuit boards to provide additional cooling for T7-T10. Alignment After everything has been assembled and the wiring has been completed, you come to the moment when you switch on the amplifier for the first time. As a precautionary measure, connect 33 fi, 5 W resistors in series with the power supply lines before switching on the amplifier, just in case something has been fitted incorrectly Also first turn PI fully to the left (anticlockwise) to set ihe quiescent current to a minim um. After this, you can switch on the power To set the quiescent current, you can measure the voltage between the emit- ter of T14 or T15 and R36 (which should be easily accessible with a measurement probe). Adjust the voltage to 22 mV. If you can do this for both output stages and the settings remain stable, you can switch off the amplifier and remove the resistors from the supply leads. The easiest way to adjust the over- drive indicator is to use an oscillo- scope, but you can certainly manage without oue. After the quiescent cur- rent has been set, drive the amplifier to just below its maximum output ampli- tude using a 1-kHz sin©' wave signal. This is best done using an 8-H load resistor with a power rating of at least 30 W, but it can also be done without a load. Measure the signals at the out- puts of Id a and IC3a r and adjust them to a minimum. If you do not have access to a scope, you can use a mul- timeter. The simplest method is to set the presets to 210 Q before soldering them to ihe circuit board. Once all this has been done, the ampli- fier can do what it's supposed to do: amplify audio signals in a very refined manner. The initial sound impressions from this amplifier are clearly reminis- cent of its predecessors with the same basic design, such as the E/ektor Elec- tronics Power Amp, HEXFET Power Amp and IGBT Power Amp. The choice of components and the compact, dou- ble-sided circuit board layout appear to bear fruit here in the form of an especially transparent, unstrained reproduction with a very spacious, well-detailed stereo image. This ampli- fier demands a pair of outstanding loudspeakers, preferably relatively large types (since they usually have better efficiency than compact speak- ers), After all the output power is rather modest, but that shouldn't pres- ent a problem for anyone outside the ranks of hard-rock, grunge and heavy metal fans. The accurate indicators are quite helpful in setting the maximum volume, and this amplifier shows once again how little power is actually nec- essary for outstanding stereo repro- duction at a respectable sound level Let there be sound! Warning This design Incorporates power supply transformers connected to the mains. That can lead to potentially lethal situations if you do not pay careful attention to the safety regulations for such circuits. Please be sure to carefully follow the instructions on the Electrical Safety guidelines page, which appears from time to time In the magazine. If the type of mains transformer shown on the schematic diagram is used, this circuit con he assembled In on enclosure as a Ctass-ll device. Attach the type label shown on Ihe wiring diagram to the assembled enclosure. 24 elekter skifronto - 3/2005 Opinions on Valves Valves versus transistors We have two audio amplifier design articles in this issue: one with valves and the other with transistors. They are just as different as peoples opinions on the issue of valves versus transistors. Does it make sense to go back to the amplifier technol- ogy of our grandparents? Is there really such a thing as the legendary valve sound ? Or is this only a question of our emotions refusing to bow to physical measure- ments? We attempt to resolve this issue by viewing it from three different perspectives. One belongs to a designer in our own Elektor Electronics lob, o second one belongs to the world of professional studio engi- neering, and a third one combines the physical and musical aspects. 3/20D5 - elgfror dftflroDifs 25 against valves as such. He thinks that excellent designs can be made using them, but his experience is limited to transistor designs, so he's reluctant fo tackle designing a valve amplifier. "Thor's the wrong challenge for me; I defi- nitely belong fo the si/icon generation . According to Ton, there are some other serious draw- backs to valve amplifiers besides their sound quality, "fn our age of environmental awareness, how con you justify marketing an amplifier with such poor efficiency? And what's more, valves have a relatively short life f and I wonder if they don't contain poisonous substances. Maybe /hey should be treated as hazardous waste E As you can imagine. Ton would never build or buy a valve amplifier. He thinks it's perfectly possible to design valve amplifiers and transistor amplifiers with equally good char- acteristics, but it's a lot harder to do so using valves. 1 if someone chooses a valve amplifier for its warm ' or 'natural sound, that's fine with me , os long as he or she is happy with it But I want a system that adds as litile as possible to the original sound; the output signal must be the best possible copy of the input signal ." Figure 7. The Schoeps At 222 valve microphone is designed hr fixed or portable use in professional environments. The 'Harmonics' rotary switch allovss the user to adjust the vobe settings in order to obtain the desired sound. The audio designer: no emotions For many years now. Tan Giesberts has been a stalwart of the small but tight-knit team that mans the flek/or Elec- tronics laboratory. During this time he has become a spe- cialist in audio circuitry. He has been responsible for most of the major audio designs we have published in Elektor Electronics , such as the All Solid-State Preamplifier (1989), the Medium Power AF Amplifier (1990), the Out- put Amplifier for Ribbon Loudspeakers [1 992},, the Bat- tery-Operated Preamplifier (1 997], the Titan 2000 [1999] and the Crescendo ME (2001) to mention but a few. This very issue features his latest creation, which 'naturally' uses transistors: the splendid, compact 'High- end Power Amplified. Given the never-ending dispute between valve and transis- tor enthusiasts over what sounds better, and in light of the fact that we feature both types of amplifiers in this Issue, we naturally would like to hear Ton's thoughts on this subject. We should start by saying that Ton is an absolute stickler for technical quality, so D1Y designs with poor perform- ance figures haven't a chance of leaving the audio lob with his approval. Ton has a clear-cut opinion of valve amplifiers: "They're simply no good I They co/our the sound , and they have poor damping , which degrades ihe sound. A transistor amplifier does a much better job of keeping the speakers under control ana it adds almost nothing to the sound. " According to him, that's not actually the fault of the valves, but instead comes from the fact that most valve amplifiers are poorly designed. What's more, the output transformer in a valve output stage Farms an additional obstacle to efforts to obtain realistic reproduction. He bases his opin- ion on the many measurements he has made on valve amplifiers over the years. Ton doesn't have anything The valve microphone: physics versus emotions By Bernhard Vollmer The author has been actively involved in quality assur- ance at Schoeps f a German manufacturer of studio microphones , for nearly two decades. As a supplier to Schoeps, his company Elvo makes the model M2 22 valve microphone /wy/w. m2 22.de/. What would music be without emotion? Should our experi- ence, ears and sensitivity take precedence over ihe techni- cal aspects? Improvements are only conceivable if well- founded understanding provides the bosis for further devel- opment Even so, comparative listening rests ore olways necessary along the way and for judging the end result. But what is the proper way fo make comparisons? Human senses are not absolute; anyone who spares himself the trouble of making comparative tests and only listens to a single product will always fall victim to his expectations ( valve sound is worm because valves are warm'). What makes things worse is that people usually don't realise this, so they base their work on preconceived notions. Generally speaking, there are two questions that always have to be anssvered: 1 . Is there a difference in sound, and if so, what is its nature? 2, Which result is better? Prolonged listening sessions are necessary to answer these questions. Whether you find something warm or cold also depends an the temperature of your previous surroundings. 3to verify the assumption that A sounds better than 'B', your only option is to directly compare them one after the other without any delay in between, possibly by switching back and forth between the two while the sound is ploying. In this way, you can recog- nise whether there is any difference, how large it is, and what its nature is. Any pause between the two signals poses a large risk of false assessment. 26 elakkr ciiEtfOiilts - 3/2005 Another Important consideration In such J A'- B' compar- isons is that the levels of the signals being compared must be absolutely identical. People cannot hear o differ- ence of only 0,5 dB in sound level os a difference in loudness. However, the signal with the higher level will unconsciously be judged to sound better, A comparative test with switchable valve signal paths is pointless If there are significant measurable differences in frequency responses, or if you do not carefully match the signal levels. Measurable differences should be elimi- nated as much as possible beFore you put your ears Into play. Otherwise you will only hear the prevailing differ- ences, which you could have already demonstrated by measurement. Many comparative tests of valve and transistor amplifiers have already been conducted, and such tests lead to comparable results iF they are done properly. To avoid going into unnecessary detail, these results can be sum- marised as follows. At low signal levels, valves are noisier, buf the differ- ences in sound are small. At medium signal levels, the differences are scarcely audible. At relatively high signal levels valves increasingly create harmonic signals., espe- cially at low frequencies. As a result, the sound is no longer neutral as with transistors, buf the result can sound more pleasant, particularly with highly impulsive sound events (such as speech and guitar music) As the harmon- ics of low frequencies are still low frequencies the result- ing sound is often described as being warmer or fuller, if the designers haven't made any gross errors, the differ- ences between valve and transistor amplifiers are much smaller than many people might think The Schoeps M222 valve microphone is designed for valve enthusiasts and can be used as a fixed or portable microphone in professional environments. The valve settings can be modified by the user to obtain the desired sound. The vatve sound: myth or reality? By Klaus Rohwer, PhD The author is a physicist and amateur jazz harmonica player ( http://www. kla u srohwer. de/j. That famous valve sound, does it really exist? Yes, it does — but it doesn't have fo come from a valve! Here we hove to make a distinction between devices for produc- ing music and devices for reproducing music. The first category Includes music amplifiers and effect generators, while the second category includes hi-fi and high-end sound systems far the living room. The first type of equips ment is optimised for high efficiency (volume) and designed to enable musicians to obtain the sound they want to produce. The second type of equipment should be optimised to reproduce the input signal in an ampli- fied form with the least possible adulteration or distortion. However, many musicians and audio enthusiasts evi- dently believe that something must glow somewhere In order to generate a warmer' sound. I consider this to be purely an idee fixe. Firstly as regards music production, what we mean here by valve sound Is primarily demanded by guitar players and blues harmonica players. The sound of a jazz guitar is just os Inconceivable without valve sound as the sound of Chicago blues. It consists of four components: - soft clipping, instead of the hard clipping characteristic of transistor amplifiers; - a compression effect, due to o power supply with high internal impedance; ^ a fuller' sound, due to additional even harmonics pro- duced by a characteristic curve that is asymmetric (even in the small-signal range); - Increased coloration by loudspeaker characteristics, due to a high-impedance output. Soft clipping results from the gradual bend in the gain characteristic (the ratio of output voltage to input volt- age), in contrast to the sudden bend in the characteristic curve of a normal transistor amplifier. Symmetric clip- ping, whether hard or soft, always produces only odd harmonics in the output signal. However, with soft clip- ping the amplitude of the higher-order harmonics drops much faster than with hard clipping, with the result that the sound is less 'hard' (Figure 2). Similar considera- tions apply to high-impedance drive [current drive) for the loudspeakers. Signal compression can also be obtained using transistors, although It is more difficult than with valves. In the present age of digital signal processors (DSPs), it can be achieved quite easily, and there are sev- eral commercially available effect generators and even complete amplifiers [such as those made by Line 6; see the web! ink] that can emulate certain types of amplifiers with extraordinary fidelity, as the author has been assured by several users. As regards music reproduction, if you want to depart from a straight-line characteristic, which Is actually the ideal for any hi-fi or high-end amplifier, you don't neces- sarily have to use valves, since the same results can be obtained using transistors, as already mentioned. We blinks: v. ww.m222.de (description of the Sc beeps M2 22 microphone) V-W.V, sen Genscbssics.de (older-model Schoeps valve amplifiers) v/ww. line6.com/products.html (effect processors and software for valve amplifier emulation) Figure 2 r With soft clipping, the amplitude of higher ordsr add harm antes m fh e c utp uf sign o I decraa $ ss m -j ch me re a u ickh tha n with hard dipping, so the sound is significantly sss harsh. 3/20&5 -ddJ jt dcdrr'rs 27 WtJl VtUiO&Y -EXPEfii ENC g "■ T "■ -‘ 1 L>S V Thanks to its robustness, the legendary ELI 56 audio power pentode has found its way into many professional amplifier units, its attraction derives not just from its appealing shape, but also from its impressive audio characteristics. We therefore bring you this classical circuit, updated using high- quality modern components. 28 ekltto f ehdfttiics - 3/2G05 Amplifier The EL156 was manufactured in the legendary Telefrinken valve factory in U!m t near the river Danube in Ger- many. The ELI 56 made amplifiers with an output power of up to 130 W possi- ble, using just two valves in the output stage and one driver valve. Genuine EL 156s are no longer available new at realistic prices, and hardly any are available second-hand. The original devices used a metal valve base which is still available, but a new design using original valves and metal valve bases would anyway be impractical, given the lack of availability at reason- able prices. Mmd® in C hints Fortunately this valve is still being pro- duced in China, using the original Tels- funken machines. A normal octal base is now used, with pinout the same as that of the EL84, 6L6, KT88 and similar valves. The devices are still not exactly cheap, but the price is not too unrea- son able and the valves are generally supplied with bases Included. Compar- ison with original Telefimken valves shows that the devices are a successful mechanical and electrical copy and are suitable for use in a hi-fi amplifier. Before we proceed to describe the design, we should first look at a few special features of these valves. In the text box we compare the basic specifi- cations of the EL 156 with those of the well-known and widely-used EL34, This information will to a large extent deter mine the design of the amplifier. In order to obtain sufficient output power, the anode voltage must be at least twice as high as the screen grid voltage. The driver circuit must be designed to cope comfortably with the comparatively low- impedance load presented by the grid leak resistors. The popular ECC83 (12AX7) is ruled out, since it operates at only around 1 mA, The ECC82 {12AU7} audio dou- ble inode can be operated with an anode current of 10 niA, and so would appear to be suitable: however, its open-loop gain is only 17, which is not enough to give adequate sensitivity, even before allowing any margin for negative feedback. The ECC81 (12AT7), however, which has an open- loop gain of 60 and which can be oper- ated with anode currents of up to 10 mA, can be used to build a suitably low-impedance circuit. Two EL 156s can be used to produce an output power of 130 W with only 6 % distortion. To improve reliability and increase the life of the valves, however, we have limited the maximum power. A genuine hi-fi output at 100 W with low distortion Is better than 130 W at 6 : =, especially when there is a large component at the unpleasant-sound- ing third harmonic. Tne whole circuit is built on four printed circuit boards, fo rmin g a monoblock. Figure 1 shows the power supply and the amplifier together. The power supply capacitors are cascaded to filter the high anode vokage in order to obtain the required voir age stability, lb supply the relatively high currents required by the screen grids of the EL 15 6s two separate high voltage sup- plies are produced using bridge recti- fiers from two isolated transformer windings (“hi 1 and To'). Immediately alter the rectifiers these supplies are connected in series and Individually fil- tered. Choke Drl, with a value of 2.3 R is rated for a current of 0,3 A and fibers the anode supply, while Dr2, with a value of 4 H and rated for 0.18 A, filters the screen grid voltage. The driver valve is also powered from the screen grid supply. The screen grid voltage must be well filtered since any hum present on it will be amplified through to the output: the screen grid has some control effect. The values suggested give good filtering and hence low hum. Radial 100 pF/500 V electrolytic capac- itors are recommended to make the power supply compact; a working volt- age of 500 V ensures adequate margin to give reliable operation even in the event of mains overvoltage. Note the discharge resistors in parallel with the electrolytic s. Tne negative grid bias voltage is provided by a diode and electrolytic capacitor: tills voltage is further filtered on the amplifier board. It is not possible to build an ultra-lin- ear amplifier using the EL 156 with a high anode voltage. The same goes for the EL 34. Tne output transformer is therefore connected in such a way that the impedance of the grid connection to the output valve is much lower than in conventional valve circuits, and con- siderably lower than the maximum permissible value of 100 kfl This relaxes the requirements on the toler- ance of the valves, and select-on-test of the valves is not required. Coupling capacitors C9 to Cl 1 have relatively large values. This Is needed to ensure that sufficiently low fre- quencies can be handled in the low- impedance circuit, Tne input and the phase inversion stages [VI and V2 respectively) have relatively low anode and cathode resistors. Tne sup- ply voltage for the input and phase - inversion stages is regulated by Zener diodes D1 to D4. The operating point of VI is therefore independent of sup- ply voltage fluctuations caused by the output driver stage, R1 and C2 block high frequencies. Capacitor C4, con- nected in parallel with negative feed- back resistor Rll, suppresses high frequency oscillations, C3, between anode and grid of Via, performs the same task. R4 and R6 are effectively in parallel to AC signals ; and, in combi- nation with negative feedback resis- tor Rll, set the overall gain. The amplifier is designed with only a mod- erate amount of negative feedback: this improves the resulting sound. An E-1220 transformer (111) with a 1:2 turns ratio is fitted at the input to the amplifier. This gives adequate input sensitivity as well as providing isola- tion. Differential or quasi- differential audio connections axe in theory less susceptible to interference and prevent earth loops. Also, the 1 :2 ratio gives an extra 6 dB of sensitivity without added noise, leaving a little more margin in hand for negative feedback. Tne printed circuit board also allows for a 3/2005 - ekhor ekrironia 29 Figure J . The heart of the valve power amplifier with its output transformer and high-voltage power supply. 1:1 connection, in which case twice the input signal level will he required for mil drive. The desired ratio can be selected using wire links. The combi- nation of C 12 and R26 compensates for the response of the transformer at higher frequencies. §f@sid! by me Valve power output stages are often designed with a stand-by function. This prolongs the life of the output stage valves, normally by switching off the anode supply, while the heater and other voltages remain. On leaving stand-by the amplifier is immediately ready for action. In view of ihe high anode voltage, an ordinary switch or relay is not suitable. We take a different approach, shorting out R22 using the stand-by switch, so that the negative grid bias voltage on the output stage valves is raised. Only a very small quiescent current now flows. According to the valve data books this is if anything preferable to switching off the anode supply as pro- longed operation with the heater on without applying an anode voltage gradually reduces the emissivity of the cathode. An LED connected to the sec- ond pole of the double -pole switch indicates when stand-by mode is active. The LED can be powered from the heater supply. To minimise hum a regulated low drop- out DC heater supply is provided, using the familiar 723 voltage regula- tor and a MOSFET {Figure 2). Tne sup- ply has been designed io minimise losses, and to this end the heater fila- ments of the two EL 156s are con- nected in series. The ECC31 can be arranged so that it operates from a 12,6 V heater supply. At double the voltage (using 12.6 V rather than 6.3 V) only half the current flows, which means that losses in the bridge recti- fier are considerably reduced. With the given component values power losses in T1 will be kept low, A further trick is used to reduce the voltage drop due to rhe curreni limii circuit. The 723 includes a silicon tran- sistor for current limiting, whose base-emitter junction senses the volt- age across the current limit sense resistors R4 and R5. Normally the sili- con transistor would switch off at Figure 2, This low drop-out DC regulator provides the heater supply , D€ hewier supply 30 chkiiji daifc-fs - 3/2005 Figure 3 . / his clever switch-on delay circuit prevents dicks . /ium and' rumo/e. about 0.6 V. Here, however, the base is provided with a stabilised bias volt- age from temperature- compensated Zener diode D2 via R7 and R8. This results in a smaller voltage drop across R4 and R5 being needed to trigger current limiting. The reference voltage produced by the 723 is divided down by R13 and R15. C4 is in principle necessary to filter out airy noise on the reference voltage, but could be made considerably smaller. Because of the relatively high value of the capacitor, the voltage at pin 5 rises slowly, crowding a 'soft start' to the heater supply. A BUZ12 FET with an Rdsqk of just 28 mil is used for Tl. It is important to ensure that the volt- age difference between the cathode and the heater is not too high as other- wise arcing can occur. The negative side of the heater supply must there- fore be connected to the negative side of the high voltage supply. Raifle and 3mm When the output stage is switched on and while it is warming up the various reservoir and coupling capacitors may charge at different rates. Tills can give rise to hum and rumble. The circuit in Figure 3 can suppress these sounds effectively. The normally-closed relay contact shorts out the output trans- former for a set time (which the valve output stage can comfortably cope with). Only after a certain interval dees the relay pull in, removing the short circuit. This approach avoids putting relay contacts in die signal path. The layout of the printed circuit board allows a relay with two changeover contacts to be Sited so that the circuit can be used for other applications, including with a stereo output st age. In our case the circuit runs from the 13 V heater supply from which it will draw a maximum of 200 mA, If the switch- on delay circuit is io be con- nected to an existing amplifier, the cir- cuit will work equally well from a 6.3 V heater supply winding, as long as there is sufficient spare current capac- ity. In this case a voltage doubler cir- cuit is used. Depending on the choice of power supply voltage a number of components must be added to or removed from the circuit, as indicated on the component mounting plan and in the parts list. Switching on When power is applied C8 immedi- ately starts to charge via R8, taking the pin 13 input of IC3.D high. At the same rime CIO charges via RIO. As soon as the input threshold voltage of IC4.B is reached its output goes low and, via the high-pass network formed by Cll and R7, generates a brief low pulse at the input to IC4.D. This signal is inverted and then used to reset the 4017 counter to zero, and then inverted again and used to reset the flip flop formed by IC3.B and IC3.C. The output of this flip-flop at pin 4 thus goes low (if it was not already low). The output of IC3.D is consequently high, Tl dees not conduct and the relay does not pull in. The output of the amplifier is there- fore short-circuited. IC2.B and 1C2.D form a 1 Hz clock gen- erator, the frequency being determined by C9 and R2. The flip-flop formed by 1C2.A and IC2.B makes this clock avail- able to the cascaded counters ICS and 106, After 100 counts the flip-flop com- prising IC3.B and IC3.C is set via inverter IC3.A. The output of IC3.D then goes low t Tl conducts and the relay pulls in. The short-circuit is removed and the audio signal is now passed through to the loudspeaker. At the same time this high signal is used to disable to counters via R5. During the switch- on process the pin 8 input to IC4.C is high, and a i Hz sig- nal is present on pin 9. The output on pin 10 will therefore also carry the 1 Hz signal, and so the LED flashes. Once the switch-on delay is complete pin 8 goes low, forcing the output of the NAND gate high. The LED now glows continuously. Switching off When the amplifier is ruined off, there is no longer any voltage present on the transformer. The transformer voltage is monitored continuously by D5 and D6 (13 V operation) or by D5 and D7 (6.3 V operation). lithe voltage is not present, 3.i i005-=:T* Sir drdranits 31 Figure 4. The amplifier seen from below. the relay drops out immediately. Diodes D1 and D9 ensure that capaci- tors CIO and Dll discharge quickly. If power is applied again, the whole cycle must be repeated. This ensures that the output is once again muted, ensuring that the unwanted effects mentioned earlier are avoided. Construction The monoblock amplifier comprises a total of three printed circuit boards and several wound components fitted into A valve is a va Ive is a valve.. • Parameter Symbol EL34 ELI 56 Units Hearer voltage U S 6.3 6,3 V Heater current ■f 1.5 T9 A Maximum anode voltage 800 800 V Maximum cathode current llmox 150 180 mA Maximum anode power dissipation fVmax 25/27.5 40 w Maximum screen grid power dissipation F\c2 ■—* 8 8/12 W Screen grid current Ig2 n/22 5/25 mA Maximum screen grid voltage 1 ' 425 450 V in class AB operation 425 350 V Grid bios voltage U 9! -39 -24 V AC grid driving voltage U gIAC 23 18 V Transconductance s 11 13 mA/V Internal resistance R i 15 20 kO Maximum grid leok resistor p i max 700 100 kn transconductance, higher current ond slightly lower grid bias voltage- Maximum drive can In some coses quantities have been rounded or guideline values shown, since not alt data books exactly agree on all ihe figures. Values shown after an oblique are at maximum drive. The EL34 and ELI 56 are genuine audio power pentodes rather than beam power tetrodes like the 616 , KT88 or 6550, They are similar to one another, but not identical in all respects. The ELI 56 requires approximately 27 % more heater power, while offering □ maximum cathode current about 20 higher. Its maximum anode power dissipation is about 60 % higher than that of the EL34. The ELI 56 also features a higher internal resistance, higher also be obtained using a smaller grid 32 ddfsH ebttfojiltt - 3/2005 Figure 5. The comforting glow of an EL I 56 in action. an enclosure as shown in Figure 4. Our prototype amplifier was housed in a seamlessly- welded nickel-plated alu- minium enclosure polished to a glossy finish. The use of al uminium provides shielding from magnetic interference which mostly originates In the fields produced by the transformers. All the ground connections must be brought together at the amplifier board and bonded to the enclosure ar a single point using a bolt and solder tag. If this driving voltage. Because of these characteristics, greater gain can be achieved using the ELI 56 than with the EL34, and os a consequence we only need a double triode in the driver stage despite our high output power. For both valves a number of details must be observed in high power oper- ation. At higher supply voltages the screen grid voltage must be fixed at a given maximum value. It Es also In gen- eral necessary to provide a fixed grid bias voltage. The maximum permitted grid leak resistor Is considerably lower for the EL 1 56 than far the EL34. The maximum value of the grid leak resis- tor is specified in the data sheet for each valve. In theory a valve con be driven without dissipating power, but In practice a small grid current flows which must be drained away. Account must be token of this when designing the driver circuit. The EL 156 can only be driven efficiently when the anode voltage is sufficiently high: power has its price! In a (node circuit using class AB push-pull operation dissipation can reach 30 W. The screen grid voltage for the Ell 56 in high power class AB push-pull operation must be ot least 350 V; for the EL34 at least 400 V ss required. 3/2005 - elektcr elednmlts 33 On the test bench Measured characteristics (all measurements taken with an 8 fl load) Parameter Conditions Value Units Input sensitivity 90 W, 1 % THD+N 1.4 Veit 20 Hz 4 Input Impedance 1 kHz 20 kHz 9 LOB kO Sine wave output power 1 % THD+N 90 W Bandwidth -3 dB, 1 W 41 kHz Slew rate 1 0 Lis step ' 5 V/ps Signal-tonoise ratio at 1 W, band with = 22 Hz to 22 kHz 88 102 d B BA 1 W 1 kHz 0.12 Harmonic distortion and noise 20 kHz 0.21 o/ /a over 80 kHz bandwidth SOW 1 kHz 20 kHz 0.6 1.43 Imermcdutaiiao distortion 50 Hz : 7 kHz = 4:1 1 W 50 W 0.5 2.6 at /a Dynamic iniermodulaiion distortion 3.15 kHz square and 15 kHz sine wave 1 1 w sow 0.064 0.33 % Damping Factor 1 kHz 20 kHz 2.9 2.3 1 „ w HOBi-i Fig Lire A shows the IotoS harmonic distortion plus noise (THD-rN) as a Function of frequency when the amplifier is driven at i W ond at 50 W. The measurement was earned out using a bandwidth of 80 kHz. As is to be expected From a valve amp! Eh' er. the distortion increases as the core in the output transformer approaches saturation. This is not a particular disadvantage as the human ear is insensitive to low frequencies and does not find higher distortion levels unpleasant. Figure B shows distortion as o function of drive level. The distortion rises from about 50 mW onwards being dominat- ed by harmonic components. The measurement was taken using a bandwidth from 22 Hz to 22 kHz in order to show more clearly she effect of harmonic distortion ot low power levels. At 90 W the amplifier starts to clip. Figure C shows the maximum power as a function of fre- quency for o fixed distortion [here I °o). The bandwidth used for the distortion measurement was 80 kHz. The maximum power starts to rail off towards the upper and lower ends of the amplifier's frequency range. At the upper end of the Fre- quency range the situation is not too bad, since generally less power is required here anyway. Things are different below 40 Hz where deep tones often demand a Jot of power. 34 e! skier electronics -3/2005 A spectrum analysis of the distortion to a ! kHz sins wave signal at an output power of 1 W is shown in Figure D. Almost all the distortion is accounted for by the second harmonic at -58,3 dB. The third harmonic lies at -80 dB, and all the remaining harmonics, along with mains hum, are below -90 dB_ The hum component is mainly due io the magnetic field of the transform- ers (50 Hz component); otherwise the 100 Hz component would be expected to be much more significant Finally, Figure E shows the effect of the Input circuit to the amplifier where a 4.7 k H resistor and a 2,2 nF capacitor ore effec- tively connected in parallel across the secondary side of the input transformer. If the output impedance of the preamplifier is greater than 50 LI the input impedance of the power amplifier has a dear effect. The upper curve shows the normal Frequency response with on impedance of 20 U, while at 600 O the frequency response foils off markedly at both the upper and lower end of the frequency range. is not done, the enclosure will act as an antenna and the amplifier will hum. The high voltages used mean that the enclosure must be earthed. Input and output connections must be isolated from the enclosure, or else stray earth currents may arise. Cable with a cross-section of at least 0.5 mm- should be used between the relay contacts and the loudspeaker outputs. Thinner cables have too high a resistance, with the result that rumble can be heard faintly through the loud- speakers during the warm-up phase. The heater connections need cable with a cross-section of 1.5 mm 2 , the earth connections cable with a cross- section of 0.75 mm 2 , the high voltage connections cable with a cross-section of 0.5 mm 2 , and finally the auxiliary supply connections cable with a cross- section of 0.25 mm 2 Operation is relatively Straightfor- ward, First check again that all the components are mounted correctly and that the wiring is correct. Next check the auxiliary voltages, leaving out the fuse in the high voltage supply for now. When mains power is applied the negative grid bias voltage should immediately be present on the valve bases, and can be adjusted using the trimmer potentiometers. For the moment, set the voltage to its maxi- mum negative value. Next check the heater voltage and adjust it to 12.6 V. If voltage can he adjusted over a range of two to three volts, but the value of 12.6 V cannot be reached, then resis- tor R10 or R12 will need to be changed. Next fit the valves. Shortly, the heater filaments should start to glow, as shown in Figure 5. We can now proceed to test the circuit with the high voltage present, it is absolutely essential that a load resis- tor rated to at least 150 W must always be connected. Do not forget to switch off the unit before fitting the high voltage supply fuse! Turn the unit back on, and connect an oscilloscope across the load resistor to act as an output monitor. Once the warm-up phase is complete the quies- cent current of the output valves can be set. Measure the voltage drop across each cathode resistor, R2Q and R21, using a multimeter. Alternately adjust the currents through V2 and V3 for a voltage drop of 4 B0 mV which cor- responds to 45 mA per valve. Next con- nect a signal generator producing a 1 kHz sine wave to the input, and grad- ually increase the amplitude of the sig- nal. Observe the output signal on the oscilloscope. It should increase io amplitude without distortion or spuri- ous oscillation until the point where it starts to clip. lithe amplifier does have a tendency to oscillate, check that the wiring is correct and that the earthing is sound. If the amplifier goes into large-amplitude oscillation as soon as it is switched on, which can be seen on the oscilloscope as a distorted square wave with a frequency of approximately 100 Hz T and heard as a hum in the transformer and output valves, switch off immediately. The effect Indicates that the output trans- former has been connected with the wrong polarity, and anode 1 must be interchanged with anode 2, turning positive feedback into negative feed- back. As long as the circuit is switched off immediately there should be no damage to the valves or other compo- nents. Note For reasons of space., printed circuit board layouts, component mounting plans and ports lists are only available in electronic form on the Internet, down- loadable from v v v. e ; e kto r-e i e_c t ro r. I c 5 . co . u k . Ready-made unpopulated printed circuit beards and kits can be obtained from the author e^o = F 'en,= e.e'e:: r onics^‘-Gr : ire.d5 ' . 3/2005 - ek Cronies 35 Visit our website www.distel.co.uk 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 OBSOLETE - SHORT SUPPLY - BULK 10,000,000 items EX STOCK For MAJOR SAVINGS CALL or see web site www.distel. co.uk A bulk purchase enables les to bring to you these GIANT7 segment dg-^ at e now affordable ctce'. i re Iff ’ cJwacter s.ize e’.es zizecoirz. re-3> illijr/ -L erg C£3LTGES ZZTC. 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By customer demand now with Eagle import as well asTsien Boardmaker 2 import. Fully integrated Schematics & PCB layout in a single application complete with forward and back annotation. Design and rules checks at all stages ensure integrity at all times. Profesional manufacturing outputs allow you to finish the design process with ease. call for a brochure, prices & CD on (0) 1684 773662 or e-mail sal6S.@numberone.com you C3r t also dovmload a demo from www.numberone.com 3/2005 - ek Sc lor derirortiQ 37 ( has a serious impact on the environment as well as on human beings. Besides classical sound reduction techniques such as insulation, researchers are trying to attack the root of the problem using electronic means. They have already had some L success. — a _ . The sound ence Sometimes it happens that an underlying physical process is well understood on paper, but the job of trans- lating the theory into the real world takes a long time. One example of this is the patent awarded to the Ger- man physicist Paul Lueg in 1 933. His idea was astonish- ingly simple and elegant. In his original patent document (Figure I) he describes how an incoming sound wave can be detected using a microphone,, converted to an electrical signal, given a ] 80 1 phase shift, and mixed with the original signal using a loudspeaker. The resuit is silence (Figure 2), Well, at least in theory the result is silence; the frequency response of the microphone, loud- speaker ond electronics along with other effects such as temperature and humidity mean that in practice things are harder than that. Anti-noise in headphones Noise has a serious impact on the environment as well as on human beings, it causes tiredness, loss of concentra- tion, nervousness ond irritability, and can lead to perma- nent hearing damage. Passive ear protection reduces noise especially in the middle and upper frequency ranges but is not adequate ai lower frequencies (Figure 3). Is it possible to use Paul Lueg $ patent in the battle against noise? Indeed it is: the most widespread and well-known application is in air travel, where active noise compensation is used in headphones for crew and pas- sengers [first doss only, of course!). The system is known as ANR [active noise reduction) or ANC [active noise cancellation), in the USA or least, there is considerable consumer demand far ANR headphones to allow music to be heard undistorted in noisy surroundings. The market fulfils this demand, with units ovoilable from thirty dollars from such well-known brands as Philips, Sony, Aiwa, Maxell, Base, Shure, Koss, Alfeo-Lansing and Jensen. Panasonic also offers in-ear headphones with ANR. Sennheiser (www.sennheiser.com) is among the lead- ing suppliers of headsets ond headphones featuring ANR, with their NoiseGard : system. An electret micro- phone capsule is Fitted in each headphone unit, along with a negative-feedback circuit and a transducer system. The sound received by the microphone which includes the wanted signal as well as the interference Is amplified and the wanted signal filtered out. The Interference signal is processed, phase shifted by 1 80 \ and added to the wanted signal. The result is sent to the transducer system. Superimposing the a nil-phase signal considera bly reduces the amplitude of the interference, whereas the wanted signal which has nor passed through the com- pensation circuit, is unaffected. NaiseGard v headsets and headphones are available in closed ond open versions. The open versions are suit- able for compensating for the noise level ond spectrum found in business jets or commercial aeroplanes. More than 10 aB or compensation is achieved over the range from 400 Hz to 1000 Hz [Figure 4). This allows the ®j U91 F. L1TES 2,043,4 1£ ram ns HUB Fi!*4 I, Fi$ f -3^ ■GTT&tt'£Y5 Figure i. Facsimile o: the eaten * document by Paul Lueg. sum of both waves W5?24 -12 Figure 2. How on;/- noise systems work • tui sadly only in theory!) Figure 3. Attenuation in dosed headphones without ANR. 3/2005-Elektof electronics 39 Figure 4 An active system with open keadphan&s works particularly well in the middle frequency range. Figure 5. With dosed headphones ANR also attenuates the la wer i req uert cie s . can be attenuated by more than 25 dB (Figure 5). The total effect of active and passive noise compensation is around 30 dB over the entire audio spectrum. Closed sys- tems ore particularly suitable for aircraft with a high noise level in the cockpit, such as helicopters and military aircraft, as well os for most propeller aircraft. These closed systems can be retrofitted with ANR kits So add active noise compensation. The picture at the beginning of the article shows a headset together with an ANR module from an ANR kit. As can be seen from the photo- graph, each module consists of two headphone loud- speakers with an electret microphone capsule positioned between the two loudspeakers. On the rear side of the module is a printed circuit board carrying SMD compo- nents. On closer inspection, the two ICs reveal themselves to be a TL064C (quad FET opampj and anMC341 19 (low power audio amplifier}. Superficially the circuit looks like a relatively simple analogue ANR circuit, but rests and experience show that it is highly effective. Kits of this type are available from outlets dealing in aircraft equipment. The modules and headset pictured are avail- able from Buscher-Ftugversand, 43466 Wolfhagen, Ger- many [WWW.! I ugvers and.de, website in German only). Active noise control In the applications of noise compensation that we have described the spatial volume over which noise is reduced is narrowly limited. Under these conditions ANC is ot its mast effective. In larger spaces and in the open air it is volume level of speech radio communications to be reduced, without compromising their intelligibility. Thanks to the open form of the headphones, voices and alarm signals in the cockpit can be heard practically without distortion. Noise, on the other hand, is consider- ably attenuated. Lightweight open headphones offer excellent comfort to the wearer, which is particularly important for long journeys. If passive ear protectors, such as earplugs or closed headphones, are combined with active noise compensa- tion, noise in the frequency range From 25 Hz to 500 Hz Figure 6. Typical bw-cost ANR n — o dp h ores hr listening to music in noisy environments. The electrodes box is connected tc the siqnai source (personal stereo etc.} and finked to m re r}eadphones r which also include rwo microphones, using on 8 -core screened cable . Anti-noise online We looked at the specialist headphones website HeadWize in our Electronics Online feature in the October 2003 issue of Elektor Electronics. This site is a rich source of information on ANR headphones. As well os on article on the various basic principles of opera- tion [1] that is well worth reading,, there is also a com- plete guide to constructing an analogue ANR circuit [2]. Somewhat more complex is the DSP application note 'Adoptive Active Noise Control for Headphones Using the TM532QC3Q DSP" by Texas Instruments [3]. A good overview of the subject, including bis of intormc- tion, ideas and links can be found an the ANC pages by Signal Systems Carp, [4] and the ANC FAG site by Christopher E, Ruckman [5]. Edge Consulting Group [6] offers a news site for acoustics, vibrations and signal processing v,ith a page on Active Noise Control' . Anyone considering adding an ANR kit to o passive headset will find detailed information at ANR- Headsets.com \7) and Headsets Jnc. [Sj. Web addresses; [1 ] htip://headwjze,com/tech/anr_tech.htm [2] http://headwize.com/projects/ shown fe.php?Fi!e=n0i5e_prj.hrm [3] www-s.ti.com/ sc/ psheets/ spra 1 60/spra 1 60.pdf [4] www.sig nalsystemscorp.com/ondndex.htm [5] http://jjsers.era!s r cam/ruckman/ancfaq.htm f6] www. ecgcorp.com/ m v aw/. a n r- h ea d 5 sts . c o m/ [8] www. heodsetsinc.com/ 40 ddclw d=[trc’.:K ■ 3/2005 much harder to achieve noise compensation. There has, however, been some progress in this direction, in avia- tion, noise compensation has been used in the cockpit since the mid-90 s, especially in turboprop aircraft and, more recently, in a business jet. The first commercial air- craft to be Fitted with such a system is the Swedish Saab 2000. The system, by Ultra Electronics Ltd. [WWW. ultra - quiet.com], uses 72 microphones in the cabin to contin- uously analyse the noise spectrum. A powerful micro- processor system processes the signals and generates a phase-shifted correction signal that is emitted though 36 loudspeakers. ANC Is particularly useful for reducing propeller noise. A similar application area is reducing tne noise produced by large ventilation fans in climate control equipment. Industrial motors can also be equipped with ANC. In fhe automotive sector ANC Is still at the research stage, but it would of course be interest- ing to be able to exploii the existing loudspeaker arrangements. It would make more sense to try actively to reduce the noise ai the point of production rather than at fhe receiver This is an area of current research, but the prac- tical results have so far been Few. Fig ure 7 shows the construction of a research project at the German Aero space Centre aimed at reducing the noise from an air- craft engine turbine. Experts calculate that a reduction of between 1 0 dB and 20 dB in noise level can be achieved. This corresponds to between one half and one quarter of the original volume. microphones lau dspe-s Vers turtm Figure 7. ActWe noise control c: source: research of the German Aerospace Cenrre. The ANC anti-noise technique can be applied not only to noise, but also to vibration. The techniques of AVC [active vibration control) and ASAC (active structure acoustic control}, which aims to reduce noise produced as a result of vibration, look to have a bright future. - J - I li i Low cost USB FIG programmers (Spring si £27, Am ££□) .plus a wide range of add-on boards and accessories... plus Incredibly easy to uss software based on flow charts... ...equals extremely rapid system development tike this mobile text messaging system built from E-blocks. ..and solutions for learning and development... njujiUw Resources for learning GPLD programming Matrix Multimedia Limited sa les@matri x mu I timed la . co.uk t. 0870 700 1831 f. 0870 700 1832 Hands on training courses train Cg courses in PlCmJcrcfR) programming, CPLD programming and EGAD Complete courses in electronics and programming Equipment for datalogging, control and PC ‘scopes ...and more at’ if 1 For rapid development of electronic systems Bin - -t> ocks ara small circuit beards eadi of which contains a block of etadmnics typ'ca‘?y feend In an e’act fdaic system. E^ucXs C£o oe programmed in C, Assembly and are t-ghtfy intagfateef v.rh Fkiwcods - which instantly con,vsits v.cjh chars into PECra'cro code. NEW 3/2005 - rVrto? clcdrcr-te 41 Remote Temperature Logger Using a DS1820 -wire temperature sensor Peter Moreton In this short article, we describe how to bit-bang a DS1 8B20 or DS1 8S20 temperature sensor device using PIC firmware written in 'C', and output the temperature values to the RS232 port, for logging on a PC, all using the PIC1 8Flash Development Board published last month. 42 slsklor slKfrorlts - 3 2G05 DStaX20 toKS PiClSP Basra 040441 - 11 Figure / . Circuit diagram of the Remote Temperature Logger hardware — all parts are connected to K8 on the PIC18F Flash Development Board t Figure 2 . Screendump showing the Temperature Logger software in action , Tne PICISFlash development board described in Elekior Electronics Janu- ary 2005 includes a header J K 8' that delivers the appropriate processor pins for SPI Micro wire, 1 2 C and 1-Wire communications to external devices. The SPI/Microwire and I 2 C protocols are supported by dedicated PIC hard- ware modules, and are quite easy to use as the hardware can be accessed using standard CIS library functions. Tne Dallas/ Maxim ‘I -Wire' bus does not benefit from a dedicated PIC hard- ware module and therefore must be implemented by 'bit-banging' the appropriate MCU pin high and low in accordance with the 1-Wire protocol specification. The I -Wire bus The Dallas / Maxim 1-Wire bus uses a single data line (hence L i-Wire’) to transmit and receive data. Each 1-Wire device must also be connected to a common ground, and optionally to a power supply. If the power supply line is omitted, the 1-Wire device can be 'parasitic ally powered' from the data line. Tne 1-Wire bus is normally held 'high' using a 4k7 resistor to Vdd. and the devices pull the bus low and release the bus to go high, in order to signal data bits. Pin RA4 of the PIC18F452 is particu- larly suited to the 1-wire protocol, as it is an open-drain pin r enabling the bus to be 'released' , and pulled high by the 4k7 bus pull-up. The bus protocol works by defining a number of signal types: a reset pulse, presence pulse, write 0, write l h read 0 and read 1. Each signal has timing parameters which must be strictly adhered to, and therefore an attribute of all 1-wire systems is the ability to generate accurate Time -slots’. Readers wishing to fully understand 1-Wire sig- nalling are referred to the in-depth doc- umentation available from the Dallas/Maxim website. m I 8x20 Temperature Sensors There are a number of similar devices in the DS1820 lineup: we have devel- oped and tested PIC firmware for the DS18S20 giving 9 -bits / 0.5 DegC res- olution and the D518B2Q giving up to 12 bits/0.0625 DegC resolution. Both parts are accurate to within 0.5 DegC. Either device may be used, by editing the DS1S2Q.C source file appropri- ately to call one of the two available functions: Celsius - Read_Teinperature_DSI8S20( ) ; // use DSI8S20 device or Celsius = Re ad_Temp e r atu re_DS 1 8 B2 0 ( ) ; // use DS 18320 device Tne pre -compiled HEX file included in the free download for this article (no. 040441- 11. zip) assumes the higher res- olution DS18B20 device is connected. Circuit Description Figure 1 shows a Dallas DS18S2G or D318B20 temperature sensor in a T092 package and a 4k7 pull-up resistor con- nected to the K8 header, as follows: -K8 pin 2 to DS1820 pin 3, V dd ; - K8 pin 10 to DS1820 pin 1, Ground; - K8 pin 7 to DS1820 pin 2, DQ; - Fit a 4k7 pull-up between DQ and V dd . It is acceptable to extend the intercon- necting cable up to several meters to allow for remote measurement, and we suggest that for external applications the DS 18 20 be protected from the ele- ments using heatshiink tubing over a waterproof seal am. 3/200i- ikSttor rial redes 43 Etektor’s online services have been restyled and extended within a brand new easy to use website. Now featuring Elektor News Service, Forum, Marketplace, Online Shop and several download options. ^ e V£tor de j HO* * *** i for nnrispc * indexed article archive hack to 1998 e s a mm a 17 for easy recognition ® search a slides Definitely worth a visit! - 5 ; .C Ml -t--. \ahoo ."A***** 1 ,di T T&™ 7 2 £ *■-* ' - 1 2" ^- V %sas» -— • ^nd"**** *!£*'«>* i^njani download construction projects (PDF) and associated software hundreds of articles available search by category, alphabetical!} and chronologically ed. TO* ,b 3 _ yte mer^ ^ C fob3t ril0 Co'^ ucrt ° ° ^ Uonr 'oS^p 5SS' WS^coiiettioft z r ru*oM ^ W auit<> w ^' T ^an « av**' . e ter^ in , . oo me con ^S«- Tr,e sSip"** 1 eis ’ yL^e ^' e an g l3V°° lS 6 the place to visit for components fools, old volumes, etc. \ e«* wur CJtatCrtrt*?' gi/uaiziAiuv UDUUU'DUIJl JUUa LPC2 1 Ox 'ARMee' Part 1: an ARM processor survey Tony Dixon BxrenNO nOPC nRW U U U U U U U T T t TDI TCK TMS nTRST TDI mJ in ' In the first instalment of a three-parr article we will look at recent developments in 32 -bit ARM based microcontrollers, concentrating on those devices that are available, do not cost an arm and a leg or require a major investment in surface mount soldering equipment! 46 e laktur ncclnmifr 3/2005 Development Board (1 ■ Overview of the ARM7TDMI core • : i Ke AR M7 core is □ 32-bit Reduced Instruction Set Computer (RISC). El uses a single 32-bit bus for instruction and data, the length of the daia can be 8 16 or 32 bits and the length of the instruction word is 32 bits. What Does TDMI™ mean? The ARM7TDMI is an ARM7 core with 4 additional features identified with letter codes, as follows T: support for the Thumb (16 bit] instruction set. D: support far debug M: support for long multiplies E: include the EmbeddedlCE module to support embedded system debugging. Thumb mode [T) An ARM instruction is 32-bits long. The ARM7TDMI proces- sor supports a second instruction set that has been com- pressed into 16-bits, the Thumb instruction set Faster execu- tion from 16-bit memory ana greater code density can usu- ally be achieved by using the Thumb instruction set instead of the ARM instruction set, which makes the ARM7TDMI core particularly suitable for embedded applications. However the Thumb mode has two limitations and these are: Thumb code usually uses more instructions for the same jab, so ARM code is usually best for maximising the performance oF the time-critical code. The Thumb instruction set does not include some instructions that ore needed for exception handling, so the ARM code needs to be used For exception handling See ARM7TDMI User Guide far details an the core architecture, the program- ming model and both the ARM and ARM Thumb instruction sets. Long multiple (M) A 32-bit Multiplier function qualifies the core for complex arithmetic tasks usually performed by a DSP, The ARM7TDMI instruction set includes four extra instructions ihot perform 3 2- bit by 32-bit multiplication with 64-bit result and 32-bit by 32-bit multiplication-accumulation |/.\AC) with 64-bit result. Debugging (D) A special hardware extension allows for Debugging within on application. This is made possible by means of a bound- ary-scan cell array around the care driven by a JTAG port and a TAP controller EmbeddedlCE (!) The EmbeddedlCE extends the debugging functions and this module contains the breakpoint and watch point registers that allow the code to be halted For debugging purposes. These registers are controlled through the JTAG test part with the aid of software debugging tools running on a computer When a breakpoint or watch point is encountered the processor halts and enters debug state. Once in a debug state, the processor registers may be Inspected os well os the Flash/EE, SRAM and the Memory Mapped Registers ARM stands for Advanced RISC Machine, where RISC means Reduced Instruction Set Computer. The ARM 32-bit architecture has been around for a number of years and has been used in products where low power consumption is essential such as for mobile phones and PDAs. Its 32-bit core is available in several guises including she ARM 7, ARM9, ARM! 0 and the recently announced ARM! } f each of which offers enhanced levels of com- puting power. The ARM was usually only available as a microprocessor device, where it required external program and data memory to complete a system. However several compa- nies are now offering a 32-bit ARM based microcon- troller with sufficient memory options for them to be con- sidered worthy microcontroller alternatives. Table I shows a selection of ARM based microcontrollers from three companies. Analog Devices, OKI Semiconductors and Philips Semiconductors. Other companies such as Atmel, NetSilicon, Samsung and Tl offer similar devices 3/2DQ5 - tliVtcr e'-rlrcrTn 47 fable 1 . ARM processor comparison matrix. Device Package RAM Flash Clock I/Os UARTs SP1 AduC7020 40-pin IF CSP 8 kB 62 kB 0.3-45 MHz 14 1 1 AduC7021 40-pin LFC5P 8 kB 62 kB 0.3-45 MHz 13 1 1 AduC7022 40-pin If CSP 8 kB 62 kB 0.3-45 MHz 13 1 1 AduC7024 * 11 64-pin LQFP 8 kB 62 kB 0.3-45 MHz 30 ) 1 AduC7025 64- pin LGFP 8 kB 62 kB 0.3-45 MHz 30 1 1 AduC7026 80-pin LGFP 8 kB 62 kB 0.3-45 MHz 40 1 1 AduC7027 80-pin LQFP 8 kB 62 kB 0.3-45 MHz 40 1 1 LPC2104 48-pin TGFP 16 kB 528 kB 0-60 MHz 32 2 1 LPC2105 48-pin TQFP 32 kB 528 kB 0-60 MHz 32 2 1 LPC2106 48-pin TGFP 64 kB 128 kB 0-60 MHz 32 2 1 LFC21 14 64-pin LQFP 16 kB 128 kB 0-60 MHz 46 2 2 LPC2124 64-pin LGFP 16 kB 256 kB 0-60 MHz 46 2 2 LPC2212 144-pin LQFP 16 kB 256 kB 0-60 MHz 112 2 2 LFC2214 1 44-pin LQFP 16 kB 256 kB 0-60 MHz 112 2 2 LPC2119 64-pin LQFP 16 kB 128 kB 0-60 MHz 46 2 2 LPC2129 64-pin LQFP 16 kB 256 kB 0-60 MHz 46 2 2 LFC2194 64-pin LQFP 16 kB 256 kB 0-60 MHz 46 n 2 LPC2292 1 44-pin LQFP 16 kB 256 kB 0-60 MHz 112 2 2 LPC2294 144-pin LGFP 16 kB 256 kB 0-60 MHz 112 2 2 ML674001 I 1 44-pin LQFP 32 kB 256 kB 1-60 MHz 42 2 1 ML6740O1 14-4-ptn LQFP 32 kB 51 2 kB 1 -60 MHz 42 2 ML6750Q1 A 144-pin LQFP 32 kB 256 kB 1 -60 MHz 42 2 1 M 16 75001 A 144-pin LQFP 32 kB 512 kB 1 -60 MHz 42 2 1 but these are usually available in larger SGA (ball grid array) packaging only, making them less suitable for hand prototyping. So what's available on the ARM mar- ket we can actually obtain ond handle? Let's have a look . hoi a number of major manufacturers in the ARM arena have on offer. Analog Devices Analog Devices (wvav. analog, com) is not a name nor- mally associated with microcontrollers, however they are about to change this view by creating a microcontroller product with a range of precision analogue Interfaces, Elekfor Electronics (leading the way!) have already pub- lished a series of articles on Analog Devices AduC812 8052 based controllers (Ref. 1). Analog Devices have released an updated range using an ARM7TDMI as the computing engine. The ADuC702x family of devices from Analog Devices integrates a 32-bit ARMZTDMI core with a 1 2-bit data converter that can have up to 16 channels supporting one million samples/sec. The ADuC702X devices also feature up to four I 2 -bit DACs with a precision bandgap reference sensitive to 1 0 ppm/~C. Other peripherals Include a comparator, a small programmable-logic array (PLA) for glue logic, an onchip temperature sensor (±3 = C) and a three-phase 16-bit PWM generator. Of these peripherals the programmable-logic array is the most interesting to Find on a microcontroller. A JTAG interface is provided for debugging the chip, while the HART can be used to program the Flash memory in-situ . An omchip oscillator will drive the ADuC7G2x at speeds of up to 35 MHz and is 2% accurate. An externa! clock Is required to run at speeds up to the 45- MHz limit. Memory options include both a 32-kByte Flash memory for the ADuC7024 and a 62-kByie Flash memory for the ADuC7026 and all include 8 kBytes of RAM. Packaging options range from a 6x6-mm, 40-lead CSP, a 64-pin LGFP and on 80-pin LGFP. These 3-V devices can operate within o temperature range of -40 to +85, or at extended temperatures up to +105, or + 125°C. Analog Devices offer o low-cost quick start development system called QuickStort, which includes o power supply, cables, evaluation board, JTAG emulator and software- development tools from Kell Software and !AR Systems. The GuickStort Development System sells for $249 and is available directly from Analog Devices, Of the devices offered, the 64-pin and 80-pin devices 48 3/2005 Timers PWM ADC DAC Notes 2 - 2 - 5 x 1 2-blt 4 x 1 2-bit PLA, temp Sensor 2 - 2 - 8 x 1 2-bit 2 x 1 2-bit FLA, Temp Sensor 2 - 2 - 10 x 12-bit FLA. Temp Sensor 2 - 2 3 10 X 12-bit 2 x 12-bit PLA, Temp Sensor, 3-Fhoss 1 - 2 3 12 x 12-bit - PLA, Temp Sensor, 3 -Phase 1 - 2 3 12x1 2-bit A x 1 2-bit FLA, Temp Sensor, 3-Phase 1 - 2 3 16 x 12-bit - PLA, Temp Sensor;. 3- Phase 1 - A x 16-bit 6-ch - i : 1 - 4 x 1 6-bit 6-ch - - 1 - 4 x 1 6-bif 6-ch - * 1 4 x 1 6-bit 6-ch 4 x 10-bit 1 - 4 x 1 6-bit 6-ch 4 x 10-bit - 1 - 4 x 16-bir 6-ch 8 x 10-bit - with external memory interface i 4 x 16-bit 6-ch 8 x 10-bit - with external memory interface 1 2 4 x 16-bit 6-ch 4x1 0-bit - 1 2 4 x 16-bit 6-ch 4 x VO bit 1 1 4 4 x 1 6-bit 6-ch 4 x 10-bit - 1 2 4 x 16-bit 6-ch 8 x 10-bit * with external memory interface 1 4 4 x 16-bit 6-ch 8 x 1 0-bif - with extern ol memory Inter face 1 - 7 x 1 6-bit 2-ch 4 x 10-bit - with externa! memory interface 1 - 7 x } 6-bif 2-ch 4 x 10-bit - with external memory interface 1 - 7 x 16-bit 2-ch 4 x 10-bit external memory r/f, 8K cache 1 - 7 x 16-bit 2-ch 4 x 1 0-blt externa! memory i/F, 8K cache are probably the mast usable by our readership for their prototyping ease. Philips Or all the companies offering ARM microcontrollers Philips (yavw. semiconductors, philips, com) seem to be the company pushing the ARM microcontroller the most and have already released an extensive range of microcon- trollers based on a 32-bit ARMTTDMt-S core [see inset]. Philips initially offered the LPC210x which featured 1 6 to 64 kB of RAM dependant on the device, together with 1 28 kB of Flash memory and all operating at 60 MHz. Other peripherals include two UARTs, 3 PI and i 2 C inter- faces, 6-channel PWM and 32-bit digital I/O port. All of which ore Fitted in a small 48-pin LQFP package! All three controller chips are based on a common system architecture approach which offers the same memory map, vectored interrupt controller and similar peripheral complements. Also common to them are the same Flash programming and updating mechanism, JTAG debug- ging and emulation facilities. These devices operate from 1 .8 V for the core CPU func- tions and 3,3 V for the I/O and peripherals, with the general I/O being 5 V tolerant. Philips has extended the LPC21xx family to include new devices packaged either in a 64-pin or a 1 44-pln LQFP, these new family members offer larger Flash memory options, an odditional 5PI interface and additional digital I/O It nes. They also included either a 4 or 8 channel ADC with 1 O bit resolution, 2- or 4-channel CAN bus interface and the option of an external memory Interface on the larger I 44-pin devices. The LPC2 ] Ox devices have o number oF development and evaluation boards from companies such os Hirek, Keil, IAR and Nohau. According to press releases from Philips we can expect future members of the LPC21xx and LPC22xx family to include Ethernet, USB, and 802.1 1 capabilities. Some- thing to look forward to! OKI Semiconductors OKI Semiconductors {www. a kf.com) are a Japanese com- pany who offer a brood range of ICs and have been pro viding 32-bit ARM-based solutions for a number of years. Oki have extended its microcontroller portfolio by Intro- ducing a new series of general-purpose 32-bit microcon- trollers based on on ARM7TDMI core These new two lines consist of the ML674001 and the 3/21105 - cteklQT efertrqcics ML675001 series. The ML674GQ1 series comprises of three products: the ML674001, the ML67Q4G02 and the ML67Q4003. While the ML675001 series consisting of the ML675001 . the ML67Q5002 and the ML67Q5003. The ML674001 and ML675001 ore ROMless parts. The ML67Q4002/3 and ML67Q5002/3 microcon- trollers offer large Flash memory options up to 5 12 kB and 32 kB of RAM. Other peripherals include 1 x system rimer, 6 x general purpose timers, 2 x PWM, watch dog iimer, general purpose I/O ports, ADC converters and 2 x DMA channels. Communications are provided 2 x UARTs; one UART Is an industry standard 1 655 OA and has 16 bytes FIFO For both send and receive, with the other having no FIFO; on FC and 5P3 interface. The chips also include an external memory interface that fea- tures a SDRAM controller allowing for ROMs (including Flash memories], SRAMs, DRAMs, or I/O devices can be directly connected to ihe on board SDRAM controller. A standard jTAG interface is provided for debugging and device programming. These chips can also be pro- grammed by using a special Boor mode program built into the device. In boot mode, the on^hip boot ROM dov, nloads a Flash writing application into the internal RAM area of the AACLL This application then handles the serial transfer and writing oF internal Flash through the UART Interface of the MCU. The chips require 2.5 V for the core CPU functions and 3.3 V for the I/O and peripherals. The series operate in a wide temperature range of -40"C to +85"C. The ML67400I series can operate at a maximum fre- quency of 33 MHz while the ML675O01 series operates □t a maximum frequency of 60 MHz r The ML675001 series has an 8-kB unified cache memory allowing the chip to operate at ihe higher clock speed. The ML67Q4002/3 and ML67G5QQ2/3 are packaged In a ] 44-pin LQFP and all the microcontrollers are of a pin-compatible design, allowing for easier upgrade from the ML674Q01 series to the ML675GQI series with a minimum of program and board layout change. Next month's issue has a heavy focus on microcontrollers and it is no coinci- dence that you will be able to read about an extremely powerful ARM microcontroller development system you can build at home, in class or In the tab. As far as we know, this is a first in electronics magazine publishing but then again who else but Elektor? References 1. Intelligent Sensor/ Actuator Controller (I5AC), ports 1 -4, Elektor Electronics October — December 200 1 and January 2002. lektor lectronics £ 69.00 /USS 112.50 (plus postage) Flash Microcontroller Starter Kit Elektor Hardv/are & Software f — ,»*»**■ v Step into the fascinating world of microcontrollers Contents of Starter Kit: 89S8252 Flash Microcontroller board (ready-assembled and tested PCS), 300-mA mains adapter, serial cable for COM port an a software bundle on CD-ROM. Article compilation on CD-ROM: * 89S8252 Flash Microcontroller Board (December 2001) * Microcontroller Basics Course parts 1-6 (January through June 2002) * Microcontroller Basics FAQ (September 2002) * Port Line and ADC Extension for 89S3252 Flash Micro Board (December 2002) * Chess Computer using ihe Flash Micro Board. Order now using the Order Form in the Readers Services section in this issue. Elektor Electronics (Publishing) FtO. Box 190 Tunbridge Weils TN5 7WY England Telephone +44 (0) 1580 200 657 Fax -+44 (0) 1580 200 SIS See also www.eEektor-electromcs.co.uk 50 =-!tkto-f tleclronks- 3/2095 J ta rlii!.cr**tS2}0Cl Affordable, Professional C/C++ Development! Everything required for LPC2000 Philips ARM7 development in a single, upgradeable kit. a Industry standard Keil UVISION3 IDE, C/C++ compiler and simulator 5 Full Simulation of LPC2000 with peripheral & interrupt support ■ - 1 0 Fully assembled LPCzug board 6 i 6 k RAM, 256 k FLASH on board S Dual CAN and RS 232 Interfaces 0 iTAG and ETM trace debug interfaces 0 Example program library 0 ull N K USB - JTAG inte rf ac e (o p ti on al ) Basic 16 k code development kits from £75 +VAT Full 16 k development kit with JTAG-USB debugger £ 24 g+VAT {Academic price just £ 149 + VAT!) For full details see www.hitex.co.uk/arm -i'i itnaassiinas * 1 m fcj fir 1 i - ; -4^.. .. . r* 3“ .SUii.i.i;;; “ i £ i - ; , . TI ■i 3 ikiC-Z .iff;.- rr , * 5 ^ — - - 1 -fcJCJ P m SOFTWARE hitex^Hi □ s Yfci.9? ME V7 TC . . ^PHILIPS lectron E 16.25 /USS 26.75 ISBN 90-53B1-184-2 CD-ROM Elektor 2004 All articles in Elektor Electronics Volume 2004 on CD-ROM This CD-ROM contains ail editorial articles, with the exception of Mew 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 uiility 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 references in any article from the archive on hard disk, or from individual year volume CD-ROMs you have available. Order now using the Order Form In the Readers Servrcf section in this issue. Elektor Electronics (Publishing) RG. Sox 1 90 Tunbridge Wells TN5 7WY England Telephone +44 (0) 1580 200 657 fax +44 (0) 1580 200 616 See also www.elektor-electronics.co.uk 3 20 Di ■ ef^lor tiCEtlMHS 51 LU m Delphi for Electronic Engineers Herman Bulle with thanks to Anton Vogelaar !n the previous article we saw how we could implement a simple calculator using Delphi. This time we connect an external keypad to the serial port, to allow the calculator to be controlled externally. We ll use the program from the last article (slightly modified) to put the numbers onto the display and to perform the calculations. The external keypad, which well build ourselves, consists of 16 keys in a configuration of 4 rows by 4 columns. When a key is pressed, a single row is connected to o single column. The combination of the exact row and col- umn is unique for each key. By activating each column in turn and then checking which row has a signal, we can determine which key has been pressed. Before we continue with the practical side we would like to point out that the complete listing for this project would 52 deleter 4sche:.io-3/20Q5 fake up too much space in ihis magazine. The listing (project Files} can be downloaded From the Elektar web- site From the Delphi course for March. We recommend that you download this first and load it info Delphi; this makes it easier to follow the next description. Connecting the hardware A CMOS type 4555 data selector Is used to activate She columns (see Figure I], This is a dual l-to4 decoder/ multiplexer. Each decoder in the !C has a 2-bit digital input and 4 outputs. Depending on the binary value of Ihe input (00, 01 , 10, 11), one of the outputs of the 1C will be driven high. The RS232 port of the computer has two output signals: DTR (Data Terminal Ready, pin 4) and RTS (Request To Send, pin 7). As a reminder we have shown the full con- nee t ion details of a 9-way RS232 connector in Figure 1 . These two signals are used to drive the line-selector inputs of the 4555. Before we can do this we should provide a supply voltage to the 1C. Since a CMOS 1C consumes very little power it Is quite easy to derive the supply from these two signals. When we're not looking for a key-press there is no need fo drive the data selector inputs. We con then keep DTR at 1' and RTS at 'O'. It is very easy to derive a symmetrical supply of ±7.5 V (^DD = 1 ^ V), using a handful of resistors, zeners and electrolytic capacitors (R1 , R2, D1-D4, Cl . C2 in Figure 1). The capacitors are sufficiently large to supply o stable voltage to the 1C during o complete scan period. All that's left is to add a little protection to the inputs since the input voltage could be larger than the supply voltage. By adding a 10 kQ to the signal path the input current is kept to a safe level. If you're using o laptop you should first measure the RS232 output voltages, as these occasionally deviate from the officio! RS232 specification [some Dell laptops had outputs of only ^5 V). In this instance the zeners ore no longer needed. We have also seen asymmetric out- puts [+5 V/0 V], so it is worth checking this out. Building the circuit or Figure 1 is fairly straightforward. The 1C, passive components and 16 keys are easily mounted onto an experimenter's board, and it doesn't take long to do the wiring either. You could use an old R5232 cable for the connection to the PC, with a plug cut oh rrom one end (Make sure that you keep the female connector on the cable, since that is required to plug into ihe PC). The wires can then be soldered directly to the board. As an alternative to individual keys you could also use a matrix keypad (obtainable from Conrad and many other suppliers). Often these come in sizes of 4x3, in which case two keypads can be 'connected in paral- lel', using just a single column from the second one. Software switching lo drive the DlR and R t S lines well have to write a bit of Delphi code. lo start with, we have to open ihe serial part. We have already covered this in Part 1 for the burglar alarm; TBend le : =CreateFile ( PChar i Fort ) , Generic_Read+ Generic Write , 0 , Nil , Gpen_Exi sting f 0 , 0) ; If FHandls = Invalid Handle Value Then Begin ShoirMessagej ‘Unable to epen c c" tr.i c s t i o r. ron-_ r ) ; Exit End; F igurs 1 .The ct rcuii tor the ex fern a/ keypad, v. h ,‘c n cc n n eels to rfi s PCs serial port. (As a reminder: Delphi programs are not 'case sensitive', unlike C and several other programming languages , Because of this, it may happen that we don ’t always use capitals and small letters the same way in different parts of the program.) In the program mentioned above this line hod an error- check added: if the port was already open it wouldn't be opened again. Windows keeps a list of various objects such as pro- grams, ports, drivers etc. These objects are given a unique code (or handle). The function CreafeFife, called above, returns the value of this code. If this value is equal to Invalid JHand!e_VaIue, which is defined in Delphi, something v/ent wrong during the initialisation of the port and the program is halted with a message and the exit command. On successful completion of this phase we have to acti- vate a few outputs. DTR has to be set to + 1 2 V and RTS t o -1 2 V. 3 - 2005 - elei.f-jr ehefrenits Jo kelo with programming the UART, a data structure (DCB see inset) is defined in Windows that contains q large set of parameters. Once all parameters have been set, ihis data structure is sent to the UARI. For our pro- gram the DCB, Flags field is the most important. In this field virtually all bits have a separate function. We have defined two constants in u Driver, which are required to turn DIR and RTS 'on and 'off'. First the current state of the UAR7 is read with the com- mand GefCommStatefFHandle, DCB). Next we set a bit in the FLAGS field to turn RTS on; DCB. Flags : = DCB. Flags OR RlisFnable The RTS output then becomes -12 V. We do something similar for DIR, but in this case we have to set the bit to 'O' while keeping all the other bits the same: DCB. Flags : = DCB. Flags AND {NOT DtrEnable) We can now send the modified DCB bock to the LJART using the command 5efComm5tate(FHandie, DCB). Since we need to use all possible combinations of DCD and RTS when selecting the columns, we have written the following procedure: Procedure Key Gut(RTS, DTE: Boolean}; Var DCB: "DCB; Begin IF FEandle > 0 Then Begin GetCom^Statef FHendle, DCB}; If DTR Then DCB. Flag- : = DCB. Flags Or DtrEnahle Else DCB. Flags := DCS. Flags And {NOT DtrEnahle); If RTS Then DCB, Flags := DCB. Flags Or Rts Enable Else DCB. Flags := DCB. Flags And (NOT RtsEnable) ; SetCoimState ( FEandle, DCB ) End End; To turn on the supply voltage to the 1C we call this func- tion with the Following parameters: Key Out{ False, True), This is done every time after scanning the keys, thereby keeping the capacitors fully charged. Scanning the matrix The next building block required For this project has to rake care of the reading of the status of the Four input lines. With the help of the procedure GetCamm- ModemStatusjFHandle, MdmSfs) these details are stored in the variable MdmSts. By applying a mask we can determine which bit, if any, is set to '12 A mask is a number which has just a single bit set to '1 , for example binary 1000 (= hex 10), binary 10000 (= hex 0020] etc. Delphi has already defined some important values far us: MS_CT5_QR - hex 0010 MS_D5R_ON = hex 0020 HS_RIKG_atT - hex 0040 m_KLSQ_QVi = hex 0080; If we now apply the mask using the Boolean AND func- tion we can determine if this bit is set. This therefore tells us If a key in this row is pressed: If MdmSts And MS_KL5D_D!S = MS _HLSD_ON Then Result : = 1 The same method is used to check if a key is pressed in the other rows. The result will be 11,2,3 or 4, depending an the selected row. These lines af code have been combined in the function Keyjnp, which returns the value of the selected row. Combining the routines In principle that is all there is to da: we know haw to select a column and how to read an which row a key Es pressed. However, these functions still have to be glued together and the result has to be shown on the display. This takes place as follows: o timer is used to call the function GefKey Ot regular intervals. This calls the pro cedure Key_Out to select a column, for example Key_out(False, False). Next we use Keyjnp to check if a key in that column has been pressed. A small section of this procedure is shown below: if no key is pressed in the first column, the variable Row becomes 0, If a key is pressed, Keyjnp returns the raw number. If raw^O then Begin cql: =2 ; Kay Out(Faise, True); rev : -Hay_Inp ; End; If TQw-i) then col; =3 In this way the entire keypad matrix is scanned. Once the row and column are known, the correct key number is looked up using the conversion matrix Map [roW/Col], as follows. We do hove to moke sure that we don't read 2 key presses if a key is held down a bit longer. This Is where the variable KeyLast comes to the rescue. IF we Insist on ar least one scan without a key press between two successive key presses, we can use that to distinguish two real key presses from o single one, which is held down too long. The previous key press should therefore always be on empty scon (with key number 0) for the current scan to be valid. Every old key press is stored in the variable KeyLast. When we're scanning for a new key press the result will only be valid if the old scan (stored in KeyLast] was 0. Adding the following line to the end of the GetKey pro cedure stops the generation of false key presses: If (KeyLast = 0} Theu Result := Key else result :=G ; KeyLast := Key; We then store the value of the scanned key in KeyLast, This nearly completes this section. We just have to make sure that the supply voltages are restored ot the end or a scan. This is done by calling Key_Out(Fa!se, True) once more, which sets DTR to + 1 2 V and RTS to -1 2 V. Apart from the procedures mentioned above for driving and reading the RS232 port, there is another procedure [KeyGet], which is used during the simulation of the program. The intention is that only one of the two func- tions is active. The other is removed using curly brack- ets (in Delphi any text between curly brackets is inter- preted os a comment). In the simulation the fag of the key is read which we 54 elelrtflf dettronks - 2 TG'OS Device Controls Block The Device Control Block contains □ list ot parameters that ore required to configure a serial port. The elements SoudRate, StopBits etc, are easily recognised. Et Is defined as a record of type TDCB and hos the Following structure: deb length boudrate flags wreserved xonlim xofflim bytes ize parity stop bits xpmeiar xorrehar errorchar eofehar evtchor wreserved 1 1 Type dword dword longint word word word byte byte byte char char char char char word Size 4 4 4 2 2 2 1 1 1 1 1 1 1 1 2 The flags are of particular interest here. Each bit in the 1 6-bii word has a unique function, which is shown in the table below: Binary ParityCheck OutxCtsFlow OutxDsrFlow DfrControlMask DfrCantrol Disable DtrControlEnobie DtrControlHa ndshake DsrSensitvity TXContinueOnXoff OutX InX ErrorChor NullStrip RtsControlMask RisControlDIsable RtsConirolE noble RtsControlHandshoke RfsCon fro Haggle AbortOnError Reserveds 500000001 $00000002 $00000004 $00000008 $00000030 500000000 $00000010 $00000020 $00000040 $00000080 $00000100 $00000200 $00000400 $00000800 $00003000 $00000000 $00001000 $00002000 $00003000 $00004000 $FFFF80G0 When the symbol S is in front of a number it means it is a hexadecimal number. In ibis case we only moke use of the numbers 50GQQQ01G (DtrControlEnobie ) and S0Q0Q1GQQ (RtsCantralEnable). The others don't really concern us here. More information can be found in the Windows SDK sec- tion accessed from the Delphi Help menu. described in the previous article. This value is put into the variable KeyPressed. In the simulation mode this value is passed as the result of the function GefKey and subse- quently processed. From this point onwards the program is the same whether in simulation mode or when using an external keypad. We now know how to read the keys. From the main pro- gram (in the unit uConsole) we start a timer that calls □ procedure every 50 ms to read the key matrix. The pro- cedure ConlrolExe (in uControl) separates the received IDs (1 to 16) into two groups. When ID < 10 a digit was pressed and a number Is being entered. When ID > 10 an action is requested. In that case we subtract 10 from the ID and execute the appropriate action From the list defined in Tmcith. As an example: 'subtraction' has an ID or rag of 1 2, Process 2 Is mtSub [counting from 0] and this generates a subtraction. When the process has fin- ished, a Screenrelresh is executed which shows the result in the display of the calculator. Functional design Observant readers will have noticed that this program consists of three functional blocks, which are the three units. The basis for this division is that complicated problems are best described as a block diagram, which is also common practice in electronics. If you have a clear division between these blacks you can describe and test the working of the individual blocks heller, and the chance of introducing design faults becomes smaller. In this project we hove split the software into three layers (in the software world we talk aboul layers In this context). We have a presentation layer (uConsofe), which receives the results from the simulated keys, □ control layer (uControl), which runs the processes in the proce- dure Control Exe and a driver layer juDriver), which takes care of the communications with the outside world via the R5232 part. In this instalment we have shown you how to implement 4 command lines and 4 status lines under Windows for use external to the computer, with only minimal hardware and a serial port. Since mast desktops have two serial ports as standard, a total of 8 command lines and 8 sta- tus lines are available for external use. Ordering Delphi 7 Borland hos mode the Personal version ot Delphi 7 available cheaply especially for this course. The CD costs € 10.00 (ten euros) and contains Delphi 7 as well as several extra files for this course. It cart be paid for by credit card [see website below) ar bank transfer [in the EC) by transferring to (please copy exactly): Bank: A3NAMRO 1BAN: NL3 1 ABN A 0577QQ2562 BIC: A3NANL2A Nome: DETLEF D. OVERSEE K Address EDELSTENENBA AN 21 USStLSTEIN Post code: 3402 XA Country: THE NETHERLANDS Reference: DELPHI ELECTOR IBAN/BIC payments should not incur honk costs when processed correctly — osk you bank far details. Cheques are not acceptable. The HCC PGG has set up a specie! website in support of this course: ,%• ... eo r-Czcs r. - ro Here you can find the most up-to-date news and extra files for the course, as well as credit card payment options. 3, 2005 - etcVlsi dstfrenits 55 > ■ This version of Solitaire is played with an array of LEDs instead of pegs, with a microcontroller behind the scenes to check if you're any good at playing. As you'll soon find, the game is challenging and addictive! +2V (?) — +■ IE *«i: lJI-( 1 — Hit * n 1 « 115 12 11 _C? iCi,C i fs Ci iM.- 22 ■ I T7 s FST F2d f=£i FC-S ft? P01 F5K> U to W ^ 1 C z; h: h : »«mip nv . v SC557 -VS OT Cfi 11 > ■ m I* EC1 Gt .= Cl Z ; = ULUZ&03 r- - £-7 ,22 =i I 5 ili ilL IE h4L 2-e T H 1 oi_ -■ - »■ -■ J-Ji £ ; ; lS tfiff V S iJ “ S ^ ■»■ f ? 1 A f*| »~1 n T IH- -XtX t i r m F Q2 +3V c_ si © IC2 © ©„, 3Y L tl tC 2 =4323 © i- QX»I2-11 Figure L At the neari of the Solitaire gome you'll find on AT90S231 3 microcontroller running some really clever software. This project is a fine instance of a microcontroller and its resident soft- ware slashing component count when implementing a logic circuit, as well as providing yet an another answer to the p e re nnial L 1 gre a t -but-\ vh at- do -y om d o - with-it? ,p question from outsiders and newbies when discussing those multi- legged beasts commonly known as microcontrollers. The design is based on the Atmel AT9Q32313 microcontroller which was selected for its low cost r speed, num- ber of I/O lines and ease of program- ming in assembly code using free tools, Fife hardware If you think of a microcontroller acting like a black box and sitting between inpnt and output devices like switches and LEDs, then the circuit diagram in Figure 1 is nothing special. It does, however, contain a few ingenious solu- tions when it comes to marrying soft- ware to hardware that's to remain as simple and reproducible as possible. The AT90S2313 micro, 101, runs at a clock frequency of 4 MHz obtained v/ith the aid of quartz crystal XL The two 22-pF capacitors serve as parallel load devices for the os cilia tor/ crystal configuration (note that the oscillator is on board the AT micro). Output devices controlled by the AT9Q micro comprise active buzzer Bzl, LEDs D1-D33 mimicking the playing field and LED D34 to confirm that the move has been performed. The buzzer sounds In response to the microcon- troller software activating the PD3, PD4 and PDS lines at the same time. This condition Is signalled by HAND gate IC2.B, with IC2.A acting as an inverter only, A similar arrangement but without logic inversion is used for LED D34 t which lights when PDO, PD1 and PD2 are logic High at the same time. Here, IC2.C is the responsible NAND gate. All Pore lines PDO through PDS are applied to the inputs of an ULN2S03 driver IC. Mote the inverting action of this 1C — it will pull the commoned cathodes of the LED sets low in response to a high level on the port lines. The anodes of the LEDs are con- nected to port lines PBO through PB7 via 220-ohm current limiting resistors, in this way, each individual LED in the playing area can be turned on an off using just 15 control lines instead of.,, right, 331 The process is called multi- plexing, Here, it relies on software. As to input devices, a number of PB on ICI lines are also connected to switches, requiring them to act as inputs as well as outputs — In a con- trolled manner, of course! Pushbutton activity is detected on port line PB7 which is exclusively an input. Switches S1-S4 are the cursor (direc- tion) controls, while S6, S7 and SS act as the SELECT. CANCEL and STALE- MATE controls. Toe microcontroller is reset at power- on by a brief logic Low level obtained from network R10-C3. The circuit does not have a voltage regulator and is powered directly from a 3- volts supply made from two series connected 1.5-V dry batteries. Rwles f@r playing Solitaire As the name suggests, Solitaire is a game to be played on your own. The board is made up of 33 LEDs laid out Ln a cross shape, where a piece on the board (or 'peg') is indicated by an active LED. 3 20Q5 - t!=Vr:j ekrticdcs 57 COMPONENTS LIST h_ O O o 0 0 o o 0 0 0 0 0 0 - / 0 00 DBD 0 0 ° a 0 0- 0 0 0 0 0 0 0 f a 51 51^9 l b & b 51 51 51 5 fa 51 51 51 £1 51 £T^ o fa do is 5b 5b 51 ITo \ 'o fk 51 5T N © il 51 § b Ns o 0 08 0 Figure 2. PCB designed for the Solitaire game. Resistors? R1 - lk£25 R 2-RB = 22QQ R9 - lOkO R10,R1 1 - 1LQ Capacitors: Cl = TpF 16V, radial C2.C3 = 22 pf C4 - lOOnF 5 em [conductors: D 14)34 = LED, 3mm, low current, red T1 = BC547 1C l - ULN2303 tC2 - 4023 IC3 = AT90S23 1 3-1 OFQ programmed, order code 030410-41 Miscellaneous: SI = on/off switch, one contact 52-SB = pushbutton, PCB mount, 1 contact, 5mm, e.g. r 160 [Conrad Electronics # 700479] XI - 4MHz quartz crystal EZ1 = 5VDC [active) bu^er BIT = 2x psdigh? (AA) b artery with holder Enclosure, e.a. Hammond type 1 59 1 DTRD (1 50 x 46 x S4mm) PCB ref. 0304 iai, from The PCBShop The aim of this game is to be left with as few pieces as possible at the end of the game. You can claim victory if you have only one piece left in the centre of the 'board'. As you will discover, that’s very hard to do! So how do you arrive at this desired state? When you turn the game on. there will be 32 LEDs lit up continuously and one, at the centre, hashing. The dashing LED shows your position on the board. The first step is to decide either to play your turn Projecv Downloads AT9GS microcontroller software. File number: 030410-1 1 .zip v. el e.k tor- elec tronics.co.uk/dl/ dl.him , select month oF publication. 58 ebbor Ebonics * 3/2G05 where your piece is or to move the position of your piece. So how do you move your position should you wish to? Listing 1 . LED control routine (AT90S program extract) 1. To move your position simply use the four direction switches S1-S4. You can move your position to wherever you like. 2. When you are positioned to where you want to be, press the SELECT button. The LED that you are posi- tioned on will flash even faster. This means that you are in jump mode. To jump a piece, which must be next to yours — up r down, left or right, but not diagonal — press the appropriate direction switch. The piece you are positioned on will jump over thar piece onto the space on the other side, and the jumped piece will disappear. You can only jump a piece if there is a space on the other side of that piece to be jumped* and if there is a piece where yon are positioned. It Is not always obvious if there is a piece where you are positioned, because the flashing LED looks the same whether it is just your posi- tion or whether you actually have a piece there. If the jump is requested and it is impossible, you will hear a beep. The jump mode will be cancelled for that move and you can then continue as before. 3. You continue this procedure until you can jump no more. The smaller the number of pieces left* the bet- ter. If (you think) a move* is no longer possible, then the player can press the ST ALEM ATE button. Depending on the score, the buzzer will produce a number of beeps indicating your result: 1 beep - < 10 rem ainin g pieces 2 beeps = 8 remaining pieces 3 beeps - 4 remaining pieces 4 beeps = 1 remaining piece! Where piece' should be taken to mean "peg* or, in electronic parl- ance* LED'! In the assembly code listing, you ll find labels like ; bad_!uck\ "excellent'* "well_done T 1 ‘very_good* and 'good' to describe relevant routines. XRIT_RED; LDI TEMP, OBI 1 1 Hill ;7 BIT TABLE FOR 7X7 LID PATTERN STS $60, TEMP ; LDI TEMP, QB11I1II11 STS 36 1, TEMP ; LDI TEMP, 0311111111 STS $62 , TEMP LDI TEMP, OBI I 1101 11 STS $63, TEMP ; LDI TEMP, 0B1H11II1 STS $64, TEMP ; LDI ‘TEMP , 0311111111 STS S65, TEMP ; LDI TEMP, 0B11111111 STS $66* TEMP ; * * LDI TEMP* SBO ; TERMINATOR STS $67, TEMP ; a r LDI TEMP, SBO ; TEST STS $68 , TEMP ; RET REFERS BJIED : CL I FUSE R27 PUSB R26 * * LDI R26, $60 LDI B27, $00 ldi comm, 01 EC ALL CON VERS ION_ROU IT H. I r IJiPDT IK COUHT3 ; RESULT IN COUNT 2 i HEFRESR LOOP: CLB TEMP * i LD TEMP, K+ ; GET RAM DATA AND INCREMENT POINTER CPI R26, $68 ;END OF COLUMN! 3REQ EXIT ROUTINE ; YES CPI FLAG , 1 ; NO BRIO FLASH A * r r CP COUNT 1 , CGUNT2 ; COURT 1 = COUNTS irr ACTIVELY BRUE WRONG RCiT'i # I ZOE TEMP, CURSOR ■ 1 WRONG ROW i FLASH A: OUT PORTD, COUNT1 * r OUT PORTE, TEMP # * ECALL DELAY # t ; NO X SHIFT COUNT J LETT 1 EQL COUNTI ■ t RJHP REFRESH LOOP * j EXIT ROUTINE: POP R26 E f POP R27 m § RET m f Construction The game is built on a double-sided printed circuit board of which the copper track layout and component mounting plan are shown in Fig- ure 2. The parts in the enclosed area (LEDs and pushbuttons) should be mounted at the solder side of the board. You may want to do the same with the on /off switch, Si. This is necessary to allow the 3/2005 - ehktof dtilrcnics 59 Figure 3. Completed board before mounting in the enclosure. hoard to he mounted as close as pos- sible to the inside of the enclosure rop panel (with, appropriate cutouts for the switches). If you want to use solder pins for the battery connec- tions, these are also best fitted at the solder side. The photograph in Figure 3 shows the board before it was fitted behind the opaque panel. The red niter enhances the visibility of the LEDs. Actually, that's achieved by making the hoard and the other component less visible! Seffwsre The complete source code listing for the program executed by the AT903 micro is available free of charge from the Publishers' website at wwwelek- tor- electronics, co.uk as file number 03041Q-il.zip* The program listing is a good example of simple code with comment where necessary. An extract of the program appears in Listing 1 — this part looks after the LED activity on the board . Finally, those of you un w illin g or unable to program your own micro for the project win like to know that the AT90S2313 can also be bought ready- programmed from us under order code 030410-41 Forest Electronics - PIC and AVR ANSI C Compiler Products FED's ANSI C Compiler for PIC or AVR processors * Fully inlegrated editor with syntax highlighting, multiple pages etc. « Full project support - include and manage multiple source files, simulator, assembler files and notes.' comments within one project • Fully integrated simulator and waveform analyser step from C line to C line, or examine code in assembler form. View device pins using a logic analyser application, • Simulator supports LCD modules, keypad, buttons. LED's, displays, analogue inputs, serial and asynchronous data. * Designed to ANSI C standards ■ PIC - Supports 18xxx, 16xxx, 12xxx series 14 and 16 bit core processors * AVR - Supports standard and MEGA core processors • Generates MPLAB/AVR Studio projects and source files and completely standard hex output Tiles. Prices from £45.00 - www.fored.co.uk for full details. W/Z-C / AVIDICY Drag and Drop rapid application development using ANSI C for PIC and AVR n~-? v i Ml jj r-H: [itHZE OfwK I ■ (*>>■- £_J 1 “2— i * Rapid Application Development for the PIC or AVR microcontroller using the C language (WIZ- C for the PIC, AVIDICY for the AVR) 9 Drag and drop your software component selections on to your design * Included components support timers, serial interfaces, S2C, LCD, 7 Seg displays, keypads, switches, port controls, many bus interfaces including ilC and Dallas IButton, AVR'PIC Hardware, and more. * Connect software components to MCU pins by point & dick ■ Parameters set from drop down list boxes, check boxes, or text entry * Links your code automatically into library events (e.g. Button Pressed, Byte Received etc.) • Automatically generates your base application including full initialisation, interrupt handling and main program loop • The complete C Compiler and AVR Simulator programs are integrated into AVIDICY - total editing / compilation / assembly / simulation support in one program • Also Includes the Element Editor to enable you to create your own components with ease, • Demonstration available from our web site Prices from £50,00 - full details from www.fored.co.uk Forest Electronic Developments 12 Buldowne Walk, Sway LYMINGTON, Hampshire, S041 6DU. 0 1 590-68 1511 [Voice/Fax) Full details from - www.fored.co.uk Email - Is info@fored. co.uk" 60 elsPiEcr elsctreriiis * 3,7005 'Swordfish" PS40M10 Hand Held U5B Oscilloscope >■ - f.f-S "'-1 Cevkh m: cwri'j*=£ t-j ranc&cs rf nscila £sta s^r«dru.-n ±-i, :r.- c m£t — ctir rata- * ; i---.> (TJtrLbTtff.i. 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TeJ aunji tist Tii . 01*1 4iatno £-■"’-2- ' t4''ni m *■ t i H# n 5-tr f Tj7-^l C3 Stingray* D51M12 Features D^U Cr-j >■ ii ;3'-: i 1 u 6Bt zrp.3, c;- 2>*cxn li Et st _-s AL'C : i — :■ rt~f sa botx — : »™=a S‘l £ j f i --- rq m ' npat-:; ,-e ' ! H 5fs t. iYvt S C,~Z: GET«Jzt C_:p T t ,• &IM— Tftjjsr Input V.li -,— i--M ■, - 5EV AC/ DCCi ^ .-g ; *;-E r ‘ ■ — • ; i r-. ;t c tTi 13 : lij.dE ”7-1^7 -r»r7g 5Kv±Ju2£i3jexH3 5*if Pimersai u£8 p.terficc - to PSU re|iA(i| £-- Pam SpcflcttE-n Tii^w nii.'pport ps-r.:ei H K7T rt il . 3-d:i2 E'rf; ■ . USB FRUSTRATED ! Looking for !Cs TRANSISTORS? A phone call lo us could set a result. We offer an extensive ranee and with a world- wide database at our fingertips, we are able to source even more. We specialise in devices with the following prefix I to name but a few). 2N 2SA 2SB 2SC 2SD 2P 2SJ 2SK. 3N 3SK -IN 6N1 7 40 AD ADC AN AM AY BA BC BD BDT BDV BDW BDX BF BFR BFS BFT BFX BFY ELY BLX BS BR BRX BRY BS BSS BS\ BSW BSX BT BTA BTB BRWBU BUK BUT BLA T BUW BUX BUY' BUZ CA CD CX CXA DAC DG DM DS DTA DTC GL GM HA HCF HD HEF ICU ICM IRF J KA K1A L LA LB LC LD LF LM M M3M ALA MAB MAX MB MC MDAJ MFE MJF MM MX MPS MPSA MPSH MPSU MRF NTM NE OM OP PA PAL PIC PY RC S SAA SAB SAD S.AJ S.AS SDA SG S£ SL SN SO STA STK SIR 5TRD SIRM STRS SYI T TA TAA TAG TBA TCTCA TDATDB TEA TIC TIP TIPL TEA TL Tl.C TMP I MS TPU U UA UAA UC UDN ULN UM UPA UPC UPD VN X XR Z ZN ZTS t- many others can also offer equivalents fat customers' risk) We also stock a full range of other electronic components Mail, phone. Fax Credit Card orders and callers welcome Cricklewood Electronics Ltd 40-42 Cricklewood Broadwav London NW2 3ET Tel: 020 8452 0161 Fax: 020 8208 1441 68000 Extensive I/O:- Serial, rDA, SPI, l 2 C Analogue, imers/Courrters, RTC, etc. ucH Panels ^Keypads, 'ery Low Power ANSI ‘C’ compiler, assemble jnker all Windows32 based. ^Source Level Debug. FuthDriver Support with^ } Libraries. \ SI Time Multitasking OS with a free run time licence. feE Unlimited email support.. (Z Jr >1 www. c ms. uk. com see our web site for full details CAMBRIDGE MICROPROCESSOR SYSTEMS LTD Unit 17-18 Zone ’D' Chelmsford Rd. Ind, Est. Great Dun mow, Essex CM6 1XG Telephone: 01 371 875644 email: sales@cms.uk.com — 3/2005 -efeklw eleclranlts review copy Altium FPGA LiveDesign Kit Designing with FPGAs pQui Goossens Modern circuits make ever more extensive use of FPGAs. Special software is required when design- ing with these devices. One of the companies that produces such software is Altium. In order to allow their software to be evaluated, they offer a cheap evaluation kit. Once the evaluation period has expired, the kit is still very useful as a development platform for your own designs! Altium 1 s background is that of a developer of various software products for elec- tronics designers. Their product range contains, among other things, compil- ers for microcontrollers, schematic and PCB drawing software and FPGA design software. To allow their soft- ware to be evaluated, Altium has offered for some time now a development platform called nanoBoard together with an evaluation version of their software. Recently, they starred offer- ing a s limm ed -down version of this board plus the above- mentioned software, which goes by the name of LiveDesign. This evaluation board costs 99 Euro (approx. £63) (excl. P&P). You get quite a bit for this money. Contents The kit contains, in addition to the development board itself, a mains power adapter and a programming cable. There are also 2 rib- bon cables included that allow the I/O connectors of the board to be connected to your own expansion PCB. From the software perspec- tive there are four CDs. These contain the evalua- rion software, examples and two presentations for Altium products. Finally, the box contains various items of documentation. It is very important NOT to discard the docket on the packaging carton. This con- tains the customer number and release -code that you will need when ins tailing the software. This installation itself is very straightforward, but it is still useful to read through the installation instructions first. Especially since in addition to die Altium software, you will also need to ins tall soft- ware from the manufacturer of the FPGA (depending on your choice tins is either Altera or Xilinx). Hardware The development board Is provided with a number of standard I/O features, such as we are accustomed to seeing on these kinds of boards (also refer to side bar). However one thing is striking, it is possible to adjust the comer frequency of the output filter of the DAG with a resistor array. The heart of the circuit is the FPGA, of course. Depending on your choice, this is either a Cyclone- FPGA (EP1C12F324C8) from Altera or a Spartan-3 (XC3S400-6FG456C) From Xilinx. As you will see short- ly, these two FPGAs are very powerful! Otherwise there is not much more to say about the hardware, except that with our board the wires between the speakers and the PCB had become dis- co miected. Fortunately, this was easily fixed with a little bit of soldering! Software The accompanying soft- ware is an evaluation ver- sion of the Protel/Nexar software suite from Altium. This version is time limited (30 days). Keep in mind that these 30 days start count- ing down from when the package is sent! It makes sense therefore, to install and try everything out immediately once you receive the package. This software looks very pol- ished and it is definitely worth the effort to try ail its features. There are too many features for all of them to he described here. It is certain- ly no exaggeration to state that this software contains every thin g that is necessary to complete your own FPGA design from be ginning to end. Even the firmware for so-called soft-core' proces- sors can be developed with this software! While trying the various examples you will quickly become familiar with most of the functionali- ty of this software. In addition to the enclosed software, you will need to 62 dehor detiroiifES - 3 '1005 Figure I. The board is available with two different types of FPGAi, Hardware Specifications - rPGA choose belween: Cyclone (Altera) or Spartan-3 [Xiltnx) -2 x 512 Kbyte SRAM - 6 x 7-segment display - 6 pushbuttons - 8-v/ay DIP switch - 8 LEDs - TEST/RESET pushbutton - system dock 50 MHz - jTAGnnterface - 2 x l/Oconneetor with 20 unused 1/O-sEgnals - R5232 connector ™2x PS/2 connection - VGA output with R/2R-DACs - stereo del to /sigma DACs - line-out output - headphone output [100 mW) install software from the FPGA, manufacturer. If your hoard is fitted with a Xilinx FPGA r then you will need the free Web-ICE-Pack soft- ware. In the case of the Altera FPGA you will need the Quartos software (also a free download). With our version of the software the latest version of Quart us was not yet supported. On Altitun's website you can find how to solve this prob- lem very easily. It is only a case of tweaking a small text file. Very simple, but you just need to know how. Soft-core This development kit is nat- urally accompanied by a number of examples. These can he roughly divided Into 2 categories, namely pure hardware and soft-core- processor based designs. Before we go any further we will explain the term soft- core -pro cess or. A soft-core-processor Is a microprocessor that is pro- grammed inside an FPGA. These processors are usually designed in a higher description language, such as VHDL or Verilog. An advantage is that any signal from inside the processor can he examined and routed to i he outside world. It is also not inconceivable to add some ‘custom' instruc- tions to the instruction set ox the processor, just for this particular application! There are three different soil-core -processors among the examples. The TSK51 is an 8051-compatible proces- sor, the TSKBQ is compatible with the Z8Q and finally there is the TSK185, which is compatible with the PIC 16- cednri from. \ - In addition to the design of the processor, there is also the necessary firmware to set this processor to work. Tire software suite therefore also contains a C-compiler, which supports these processors. Designing hard- ware, software and now even your own processor can be done in just one soft- ware suite! Examples The supplied examples range from simple to extremely complex. So there is something to appeal to anyone. There are examples that produce some simple effects using the LEDs, but there is also an example of a 3/2005 -ekhcf ckrtrcnia 63 review copy Figi^e 2. Working with the source code for a soft-core -processor Figure 3. Wirfi /ft ess virtual instruments you can make measurements inside the rPGA . complete ‘Pacman’ video game with PS/ 2-inputs for mouse and keyboard and a video output for the screen! There are also some inter- mediate complexity exam- ples such as a clock with alarm function. To get an impression of the scale of the designs in the FPGA, we compiled an Included example that con- tains no less than 4 proces- sors (TSK165). Then we looked at a report from the compiler software and it appeared that this design used only about 1/3 of the available resources of the FPGA! All examples can be pro- grammed in the FPGA after compilation and be tested directly on the board. Debugging The real power of the soft- ware is really only utilised when you want to earn/ out measurements on your design. It is obviously impossible to measure inter- nal signals ox the FPGA with a probe, so most examples are provided with a JTAG interface. With tiiis you can (without disturbing the operation) make real-time measure- ments inside the FPGA. For this purpose, several meas- uring instruments are built into the software. A logic analyser, an oscilloscope ( dl git al , ob vlo u s ly ) and some I/O -blocks that let you determine logic levels with some buttons. To make this all complete, there is the possibility to debug the processors with their firmware. Registers can be changed, break- points can be placed, memo- ry can be examined, etc. AH this can be done! Finally This FPGA development kit offers much for the money. Unfortunately the software is no longer usable after 30 days. However, you can con- tinue to use the board in combination with the free software from the FPGA chip manu f a cturer s . Although, it will take a little getting used to after having been spoilt with the soft- ware suite from Aitinm. The diagram for the design- kit is supplied as a Prate! schematic file. This means that after the end of the evaluation period the schematic cannot be viewed again. If you would like to continue to use the board after the software has expired it makes sense to print the schematics early on. Without these schemat- ics it is not easy to figure out which pins from the FPGA are connected to what sec- tions of hardware and con- nectors! Purchasing this software is not really in the league of the average hobbyist (both parts of the software togeth- er cost around 10,000 Euro!). The free software from the FPGA manufacturers, how- ever, is still very usable to realise your own designs with tills kit, after the 30- day period. Because an FPGA with suffi- cient capacity has been used, it is not very likely that your design won t fit in this device. Furthermore, the FPGAs are so quick that it has become relatively easy to design complex and fast equipment at home. The nicest aspect of this is that when changing the design there is no need to immedi- ately reach for the soldering iron, A simple button push is sufficient, the rest is carried out by the PC and hardware. This development kit offers more than enough possibili- ties to begin exploring and experimenting with FPGAs. You will quickly be sur- prised as to what you can do with itf Internet links YAyw-altium.com YvvAy.QlLerQ.com wvAY.xilinx.com 64 cisklor effirtronics - 3 '20D5 What are FPGAs? FPGA stands for Field Programmable Gore Array. These ore chips that are provided with a large number of small digiiol building blocks, each of which can perform a simple Function. The inputs and outputs from these building blocks con be connected to inputs ond outputs from other blocks via a matrix of signal lines, hence the term Gate Array. When the power is first turned on, the inputs and outputs are disconnected from the signal matrix. The chip can be programmed via o programming port. This means that the designer, with the aid of a programming file, determines which inputs and outputs are con- nected to each other, so that the chip will perform a certain function. It is easy to imagine the FPGA as o [very] large experimenting board with tens of thousands (or even hundreds of thousands) of logic ICs, which are not interconnected. Connections are made between these chips according to ihe wishes of the desionen An advantage of an FPGA is that all these building block are on one piece of silicon and that each building block has □ very high propagation speed (in the order of a fev/ nanoseconds). This means that very fast digital circuits can be realised with an FPDA, which cannot be done with a handful of logic ICs. FPGAs are often also provided with o number of additional features, such as block of memory hardware multipliers, etc. Some FPGAs also contain a built-in processor that con be connected with the design in ihe FPGA. Depending an the capabilities of the FPGA, it can sometimes be difficult [as we described in this article) to implement and apply your own processor in an FPGA! Personal ideas In ihe process of authoring this article I'Ve gradually become very enthusiastic about the possibilities for ibis board. One of my hobbies (In addition to electronics, oF course) is building and flying model aeroplanes. As it happens, I have a nice aeroplane that has a reasonably spacious fuselage, which accommodates this beard easily Originally I had the idea of fitting a camera with accom- panying transmitter in there, so that 1 could see from the ground an a TV She world from the cockpit of my mode! aeroplane. Afterwords ! wanted to add all sons of bells and ’whistles. While experimenting with ibis board from Aliium, I noticed how powerful the FPGA is that has been used here. That's why 1 imme diotely took up the plan to go o little Further, namely converting the video signal from the camera to a digital signal with a video decoder and send it to the FPGA, In addition 1 would like to place a number of sensors for measuring the air pressure (l.e. height and vertical speed) ond motor temperature, and possibly a GPS module to determine the position. This information is also (in digital Form) sent to the FPGA, The FPGA will then combine the measurement daio with the camera signal and send the output video signal first to an encoder and men to the transmitter. In this way J cannot only see the real-time picture from the cockpit but also see various rele- vant data at the same time! Who knows, maybe I will even fit on autopilot in my aeroplane, fhat would make my hobby a lot cheaper! 3/2005 - tk'mi eiedranks 65 Compact and universal Burkhard Kainka - 1 jm ■ k : j _A-4 t 1 V r V V fhe right crystal controlled frequency at the right time: With this DIP outline oscillator there's no need to wait for a specia crystal to be made up. You can program its frequency precisely using the RS232 port of your PC. Low phase noise is a feature that makes this PLL oscillator suitable for demanding RF applications also. i This multipurpose clock generator cir- cuit uses the CY27EE16 pro gramm able oscillator of the CyberClock family of devices from Cypress. Regular readers will remember this chip from the November 2004 issue of Elektor Elec - ironies . The entire oscillator circuit shown in Figure 1 comprises of little more than the clock generator chip together with a voltage regulator and fits neatly onto a small PCS. Altoget- her it makes an extremely versatile clock generator that will no doubt hnd a use m many applications. The 10 MHz reference crystal shown in the parts list is fitted to the FOR via a socket. A different value may be sub- si fluted if it is necessary to provide two or more specific output frequen- cies simultaneously for a particular application. The chip communicates with the PC over an I 2 C bus using handshake sig- nals of the RS232 computer interface. 66 e!=klc; e'ftfiQiiia ■ 3/2D05 Data from the slave is read on the CTS line. The signals DTR and RTS are read by DCD and DSR and these may be used later in software for possible expansion of the design, they are also used to control the data rate in a USB/RS232 adapter. The software allows the user to load settings to the internal EE PROM or RAM register. In many applications the oscillator chip will be built into equip- ment and its clock frequency parame- ters will be programmed in the E EPROM. It will always be possible to change the value later if the frequency needs to be altered. In other cases where the application calls for the out- put frequency to be selectable the con- nection cable will remain attached to the PC and new data can be sent to the clock chip whenever necessary The PCB is the same outline as a 24 pin DIL 1C. Two rows of pins can be fit- ted to allow the assembly to be plug- ged into a standard 24 pin IC socket. A LM317LZ Figure 1. The programmable clock circuit diagram. COMPONENTS LIST Resistors: R1 - 1B0Q R2 - 1 1 On R3, R4 = 4kQ7 Capacitors: Ci ,C2.C3 = lOOnr ceramic Semiconductors: IC 1 = CY27EE i 6ZE 1C2 = IM3 17LZ, T092 D 1 , D2 ~ Zener diode 4.7V 0.5 W Miscellaneous: ICtOMHz quartz oscillator module with socket 10-way boxheader 1 Q-v/oy fiarcabie with iDC socket and 9- v/ay sub-D socket PCB, ref. 040361-1 from The PCB Snap Nate: Ready populated ana resW boards os watt os core boards available from AK- Modul-Bus GmbH, Germany ( - y w . g - , - n lady: us . de b o o o o o o o o O G O O O O o O OD OOOO O O O O Oj= ljr =^^^-0 O q q r j °° oooo 6 q O oo oooooooooooo Figure 2. ihe PCB is arranged' as a 24 pin DIP outline 3/2005 ■ ciTkior drifrcnfo 67 % CV 27 EE 1 C Figure 3 . Frequency setting using CyberC locks. Figure 4. The Clock. exe program. 1 fb= way upi scjil l urnmrtrOnji lauutrp r** h ic cable connecting it to the PC. Tills is not too much of a problem because the cable is only needed when the osclUs- " CO* rt J uun ^ njjjruynsmrdn -y .™ Li^ u&t ^ and dock signals to the CY27EE16 axe also connected to pins on the IC socket so that an omboaid processor in the target system with suitable software routines could reprogram the clock generator directly Table 1 shows the pin out assignments of the 24-pin socket. Assembling the components onto the PGB should not be too much of a pro- blem for anyone with a little expe- rience in mounting SIvID components. One method using generous amounts of solder and desoidering braid to clean up has often been described in Elektor Electronics. When the finished PCB is connected to a suitable power supply a voltage of 3.3 V can be mea- sured on the CY27EE16 supply pins and the crystal should be oscillating. All signal output pins will however be set to high impedance mode until the chip is programmed. The program Chck.exe together with some helpful examples can be downlo- aded free of charge from the Elektor Electronics web site vAvw.eIektor-elac- rronics.cQ.uk . The file number is 04035 1-lLzip. For complete chip pro- gramming flexibility it will also be necessary to download the Cyber - Clocks program and this can be found at y,~a~w cvore ss . c om . €hsmge $h& B&ffistgs wi th Cybes , €l©sks All the configuration data for the chip can be programmed using Cyber- Clocks. It is necessary to specify the which output pin (or pins) will be used and the desired output frequency. Figure 3 shows an example using the Figure 5- The programmable divider and register. (able 1, Pin-out assignments for the oscillator PCB. , l 3.3 V O/P +5 V 24 2 Ground Ground 23 3 Clock 1 Ctack6 22 A Ground Ground 21 5 Clack2 Clocks 20 6 Ground Ground 19 7 Ciock3 Gack4 18 8 Ground Ground 17 9 SCI Ground 16 10 Ground Ground 15 1 1 SDA Ground 14 12 Ground Ground 13 63 ^ktordetlftinEcf - 3/2Q05 Figure 6 . Advanced Mode settings. CLK 5 output. Information containing all register values and settings are sto- red as a binary file in the PC and downloaded to the chip. Besfe transfer using Cloek.exe The Clock.exe program writes data into either the internal EE PROM of the CY27EE16 or into RAM. The register contents in RAM become immediately effective whereas the settings stored to non-volatile EE PROM will only become effective after the chip undergoes its next power up when all EE PROM data will be written to RAM, The software includes some example files to gene- rate different frequency outputs from a 10-MHz reference dock. The buttons labelled 'upload E EPROM' and 'upload RAM' transfer the Dinar/ file generated in the Cypress CyberClocks program. In the lower part of the program win- dow there is possibility to directly change the frequency settings without recourse to the Cyber Cloaks program. It is assumed that a 10 MHz crystal is used and a sample file with the des- ired output configuration has already been loaded. Clock.exe does not change all the registers but just pro- grams new values to the PEL and the 7 -bit divider DIV1N for didder bank 1. The maximum PLL range from 100 MHz to 400 MHz is used with the smallest step change of 250 KHz. The different output frequency ranges are produced by the post divider and give the following step changes in output frequency: Output frequency in MHz Steps In kHz 1 ro 4 2.5 2 to S 5 4 to 16 10 | 1 0 to 40 25 25 So 100 62.5 Multiple sleek sources from one ossillofos’ The cyhercJock clock generator has six frequency outputs and its impor- tant to understand how the internal divider arrangement places limita- tions on programming the output fre- quencies. There are two 7-bit pro- grammable internal divider banks that can be configured to divide down the output of the crystal or the PLL. Two alternative dividers in each bank offer fixed division ratios. The PLL output can for example be made avai- lable on three output pins, the first pin will be the PLL frequency divided by 127 s the second will be the PLL fre- quency divided by 2 and the third will be divided by 3. The other divider bank can be used to divide the crys- tal frequency. A more detailed des- cription can be found in the data sheet from Cypress . In a typical RE application there is often the need for more than one fre- quency source in the whole system. The CY27EE16 contains only one PLL but it can generate several dif- ferent frequencies if the crystal fre- quency is chosen carefully. Figure 5 shows an example where two oscil- lator frequencies are produced by the clock generator for a DRM type receiver. The desired second oscilla- tor frequency of 467 KHz is achieved with a deviation of 300 Hz using a division factor of 19 after the crystal oscillator. The first oscillator fre- quency uses the PLL and achieves the desired frequency of 6550 KHz with an offset of just 16 Hz. The Cyberclock also allows fine adjust- ment of the crystal frequency with a programmable load capacitor. Its value can be adjusted in the range from 7.8 pF to 32 pF in steps of 0.1 pE To try out this feature the author required a highly stable precise frequency of 45.012 MHz for a receiver with a 4b MHz crystal filter to give a 12 kHz output signal. A rummage around the spares box soon provided a number of suitable crystals and with the help of the calculator it was determined that a standard 8.867238 MHz PAL crystal would again be suitable and would proride an output frequency closest to the required signal. The frequency difference was only - 210 Hz or 4.7 ppm. The crystal would only need to be "pulled' by 40 Hz to achieve exactly the required output fre- quency. This last adjustment was made using the time-honoured princi- ple of trial and error and the final trim- mer' value was found to be 22 pF: 3/2005 - dAl&r thdronics 69 E-ONLINE Audio-tweaks From demagnetising to varnishing Harry Baggen For true audio enthusiasts, nothings too far out when it comes to improving the sound quality of their hi-fi or surround-sound systems. Naturally, you can spend a lot of money on cables and other accessories, but there are a lot of possibilities that go even further, such as equipment modifications and special treatments for LPs and CDs. ^ = : r =dt ■ r - j | . 2, -C ” V-.-r ■ •; r 7 '\5eiyrfi [ I □ -- 1 -,t i : i j til Hitt 7 ////AM % iff/H kMfti * 1 ' fii 1 ii In ■ - ft m iiU »•> Despite the mountains of cheap audio equipment sold every year, there is still 0 sizable group of people devoted to true hi-fi reproduction In both stereo and sur- round-sound versions. Many of these confirmed high- enders even resort to rather unusual methods to squeeze the lost drop of performance out of their gear and obtain just o smidgen more detail from the speakers. Here v/e have collected several of these methods which range from quite serious to rather questionable. Let's start off with a few in the fat- ter category. There are various tips going around for making CDs sound better. For instance, it's supposed to help if you put the CD in the Freezer For a few hours before playing it. That doesn't cost anything, so it's easy to try it out. Another way to improve the sound of a CD is to demagnetise it before you ploy it. Several manufactures market commercial devices for this purpose. One of the strangest tricks For improving the sound of o CD is one that we recently found on the Audio Tweaks website [1]. There someone recommends spraying a bit of Pledge (□ sort of wax polish for wooden furniture) into the air and then dragging the data side of the CD 70 flcktor cEsctreda ■ 3 "2005 through the aerosol fog hanging in the air [2], Thor will cause microscopic drops of liquid to adhere to the sur- face of the CD, which apparently affects the playback. This seems rather risky to us from a technical viewpoint, since residues of the polish will most likely be spun off from the CD and end up in the drive, and that can have disastrous consequences ior the laser and the slide mech- anism. At least you can t soy we didn't warn you. This site has a collection of more than 300 audio tweaks, and it's quite amusing to browse through them. Another rather unusual tip involves 'C37 lacquer' a sort of magic potion formulated by the Austrian violin maker Dieter Ennemoser [3]. It s a sort of violin varnish that also appears to have special properties far audio equip- ment, and everything that is coated with it will only vibrate at natural harmonic frequencies (based on car- bon at o body temperature of 37 r C — hence the name]. We must admit that if you coat your speaker cones with this stuff, ft s bound to affect the sound quality. Herr Ennemosers site also has various links to sites with descriptions of treating amplifiers and the like with this varnish. Even coating the ICs on a circuit board is sup- posed to lead to a perceptible Improvement in sound quality. But you should first read what various people have to say and draw your own conclusions. The activities the American company CyroPlus [41 are less strange., and they also have a technical explanation. What they do is to chill interconnecting cables ond speaker cables, as well as Individual valves and ICs or even entire circuit boards down to absolute zero. The idea behind this is that It restores the original crystalline structure of the materials in the cables or components. You can buy treated cables from them, but you can also place an order to hove your own cables chilled. The prices are quite reasonable, aside from the cost of ship- ping to the US. It used to be that tuning or tweaking hi-fi equipment was primarily something done by hobbyists, but in the mean- time it has turned into a professional business. Well- known companies such as Von Medevoort [5] in the Netherlands ond Swoboda Audio [6] in Germany, offer modified consumer equipment with all sorts of tweaks, such as optimising the damping of the enclosure, upgrading the power supply, or modifying subctrcutts (such as using special opamps in a CD output stage). There's no doubt that such extensive measures definitely affect the sound quality and can yield very good end results. In most cases, though, it's a costly enterprise, since it takes a lot of work and rime to modify an existing piece of equipment. Finally we hove a nice idea for the minimalists among our hi-fi enthusiasts. When you think of a hi-fi amplifier, you usually think of a big box with o hefty power supply (and just now we want to leave aside controversial issues such as how much feedback gives the best results). Under the motto 'keep the circuitry ond circuit-board tracks between the input and output of the amplifier to a mini- mum', the German Charles Altmann \7] has created an amplifier stage consisting of nothing more than a power 1C on a circuit board with input and output sockets _> Jt '3 ^ LU “ . r] n . VjiiT a taUEinaia'rr- Dieter Ennemoser C37 Sound Sensation 11 tfra H : t- t i EAR F I irr h zr&iT. -i: lt^I xc^briiKWrsi at* j ri, 3 -Jfc-gn » 4 h 3 Si— J J _nd » .*» i ■ unjfrMwftjw dr cfc^ feieMTfa — -i id aucx folia die Seca, ciei t vr,. (■-iVd’iet rund Lin diete* r"_> —■ - * and a potentiometer It bears the suggestive name J BYOB amplifier', and the circuit is powered by a car battery. As Altmann finds that a metallic enclosure generates undesir- able vibrations, the amplifier is supplied on a small nicely finished wooden board. The photos on his website should inspire quite a few audio enthusiasts to make something similar on their own. As you can see, hi-fi ss truly an open-ended subject! •14511 1-1; Internet addresses [f] Audiolweaks: wmaudi 0 lweaks.com/collecli 011 _astend.hf 1 n [2] Pledge-ftp: www.aadiofweaks.cam/tweab/tweak_26S.Kfin [3] Dieter Ennemoser: www.ennemoser.com/ [4] CryoPIus: v/ww.cryoplos.(am/audio.html [5] Van Medevoort upgrades: www.aadiDart.nl/rtl/upgrade.hfml [6] Swoboda Audio: www.swobodaoudio.de/ [7] BYOB amplifier: www, mother-of-tone.com/byob.hlm 1 2005 - drifM ruHrl:* 71 Quasar Electronics Limited PQ Box 6935, Bishops Stortford, CM23 4WP Tel: 0B70 246 1826 Fax: 0870 460 1045 E-mail: sales@quasarelectronics.com Add £2 .95 P&P to aLE UK orders or 1 st Class Recorded - £4.95, Next Day (insured £250) - £7.95, Europe - ES.95, Rest of World - £9.95 {order online for reduced price UK Postage). We accept aJJ major credrt/debrt cards, Fifeke cheques/PO's payable to Quasar Electronics. Prices include 17.5% VAT. Call novr for our FREE CATALOGUE with details of over 300 krts, projects, modules and publications. Discounts for bulk quantities. ItAIL ORDER ONLY. VISA © ©UASAR electronics >00 mo’s rr#e flgtt ccooecftrar Motor Drivers/Controllers Here are just a few of our controller and driver modules for AC, DC, unipolar/bipolar stepper motors and servo motors. See website for full details. NEW I Bidirectional DC Motor Controller Controls the speed of most common DC motors (rated up to 32VDC/5A) in both the forward and re- verse direction. The range of control is from fully OFF to fully ON in both directions. The direction and speed are controlled using a single potentiometer. Screw terminal block for connections. Kit Order Code: 31 66KT - £14,95 Assembled Order Code: AS3166 - £24,95 DC Motor Speed Controller (5A/1Q0V) Control the speed of almost any common DC motor rated up to 1 00V/5A. Pulse width modulation output for maximum motor torque at ail speeds. Supply: 5-15VDC, Box sup- plied. Dimensions (mm): BOWxICOLxSOH. Krt Order Code: 3QS7KT - £12.95 Assembled Order Code: AS3G57 - £19.95 NEW! PC Standalone Unipolar Stepper Motor Driver y «Q Drives any 5, 6 or &4ead unipolar stepper motor rated up to 6 Amps max. Provides speed and direc- tion control Operates in stand-alone or PC- controlled mode. Up to six 31 79 driver boards can be connected to a single parallel port. Supply: 9V DC. PCS: SGxoQmm. Kit Order Code: 31 79KT - £9.95 Assembled Order Code: AS3179 - £16,95 Assembled Order Code: AS31 1 3 - £24,95 NEW! Bi-Pol ar Stepper Motor Driver Drive any bi-polar stepper motor using externally sup- plied 5V levels for stepping and direction control. These usually come from software running on a computer. H Suopjy: 8-30V DC. PCB: 75x85mm„ Kit Order Code: 31 S3KT -£12.95 Assembled Order Code: AS315B - £26.95 Most items are available in kitfoim (KT suffix) or assembled and ready for use (AS prefix). CREDIT CARD SALES f 17 W A Controllers & Loggers Here are just a few ofthe controller and data acquisition and control units v/e have. See website for full details. Suitable PSU for all units: Order Code PSU445 £8.95 Rolling Code 4-Channel UHF Remote State-of-the-Art. High security. 4 channels. Momentary or latching relay output. Range up to 40m. Up to 15 Tx : s can be leamt by one Rx (kit in- cludes one Tx but more avail- able separately). 4 Indicator LED s. Rx: PCB 77x85mm. 12VDC,-6mA (standby). Two and Ten channel versions also avertable. Kit Order Code: 31 8QKT - £41,95 Assembled Order Code: AS31 80 - £49.95 Computer Temperature Data Logger 4-channel temperature log- ger for serial port. £ C or a F. Continuously logs up to 4 se pa ra t e s e nso rs 1 0 cate d 200mA from board. Wide range of free software appli- cations for storing, using data. PCB just 38x33mm. Powered by PC. Includes one DS1820 sensor and four header cables. Kit Order Code: 31 45KT - £19.95 Assembled Order Code: AS31 45 - £26.95 Additional DS1820 Sensors £3.95 each NEWf DTMF Telephone Relay Switcher Call your phone number using a DTMF phone from anywhere in the world and remotely turn onofr any of the 4 relays as desired. User settable Security Password, Anti- Tamper, Rings to Answer, Auto Hang-up and Lockout. Includes plastic case. Not BT ap- proved. 130x1 10x30mm. Power: 12VDC. Kit Order Code: 31 40KT- £39.95 Assembled Order Code: AS31 40 - £49.95 Serial Isolated I/O Module Computer controlled 8- channel relay board. 5A mains rated relay outputs, 4 isolated digital inputs. Useful in a variety of control and sensing applications Controlled via serial port for programming (using our new Win- dows interface, terminal emulator or batch files). Includes plastic case 13Gx1COx30mm. Power Supply: 12VDC/5D0mA. Kit Order Code: 31 08KT- £54.95 Assembled Order Code: AS3108 - £64,95 rrn ni'iiri'P! i>#f aviii jr Infrared RC Relay Board Individually control 12 on- board relays v/ith included infrared remote control unit. Toggle or momentary. 15m+ range. 112x122mm. Supply: 12VDC/Q.5A Kit Order Code: 3142KT - £41.95 Assembled Order Code: AS3142 - £51.95 PIC & ATMEL Programmers We have a wide range of low cost PIC and ATMEL Programmers. Complete range and documentation available from our web site. Programm er Access ones : 40-pin Wide ZIF socket (Z1F40W) £15.00 18V DC Power supply (PSU010) £19,95 Leads: Parallel (LDC136) £4.95 /Serial (LDC441) £4.95 / USB (LDC644) £2.95 NEW! USB 'All -Flash" PIC Programmer USB PIC programmer for all "Flash" devices. No external power supply making it truly portable. Supplied with box and Windows Software. ZIF Socket and USB Plug A-B lead not incl. Kit Order Code: 3128KT - £34,95 Assembled Order Code: AS3128 - £44,95 Enhanced "PICALL" ISP PIC Programmer Will program virtually ALL 8 1 to 40 pin PtCs plus a ranue If of ATMEL AVR,SCENIX SX and EE PROM 24C de- vices, Also supports In Sys- tem Programming (ISP) for PIC and ATMEL AVRs. Free software. Blank chip auto detect for super fast bulk programming Requires a 40-pin wide ZIF socket (not Included). Available in assembled format only. Assembled Order Code. AS3144 - £49.95 ATMEL 89xxxx Programmer Uses serial port and any standard terminal comms program 4 LED s display the status. ZIF sockets not included. Supply: 16-13VDC, Kit Order Code: 31 23KT -£29.95 Assembled Order Code: AS31 23 - £34.95 NEW! USB & Serial Port PIC Programmer USB .Sena I connection. Header cable for ICSP. Free Windows i software. See website for PICs t&upported. ZIF Socket/USB Plug A-B lead extra. Supply: 1SVDC, Kit Order Code: 31 49KT -£34.95 ' Assembled Order Code: AS31 49 -£49,95 www.quasaroIoctronies.com Secure Online Ordering Facilities Full Product Listing, Descriptions & Photos Krt Documentation & Software Downloads -r5V Ti-sV Bidirectional S/PDIF Converter Joseph Kranz Although 5/PD3F is the standard when it comes to conveying digi- tal audio signals in consumer electronics equipment, difficulties may be encountered if you try ro connect up two apparatus having digital connections. Cheap equip- ment usually has only one con- nection [coaxial or optical), while mare up-market products will gen- erally offer both variants. When interconnecting CD and DVD players, MD recorders and sur- round receivers yaull soon find that a converter from optical to coaxial or the other way around is useful if not indispensable. The bidirectional [two-way] S/PDIF converter shown here employs just one 1C to handle the conversion both ways. The ITC49Q (1C3) is a differential line transceiver originally Intended for use In RS485 applications. Using R2, R3 and R4 the driver port used here to get from coaxial to optical is biased to the centre of ihe permissible common-made voltage (between -7 V and -5- 1 2 V for this !C). Moreover, a small onset is added (approx. 0.2 V) fo ensure a low level is defined in the absence of an S/PDIF signal. The input signal is supplied by Tr 1 , a small transformer you need to wind yourself on on Epcos core type 64290-L44-X830. The pri- mary consists of six turns of 0.3 to 0,5 mm diameter enamelled copper wire (SWG3Q SWG26), The secondary side is made by winding 1 2 turns of the some wire. Incidentally C3 pre- vents the transformer secondary from short-circuiting R3, The capacitor has o negligible effect on the /PDIF signal. That concludes the more complex port of the circuit, the receiver section of SC3 being followed by a dead standard application cir- cuit around the TOTX173, an opt i co l S/PDIF driver. The other part of the circuit, i.e., the converter from optical to coax- ial, is even simpler. Optical receiver !C2 works happily with ihe addition of just one capacitor that decouples the supply voltage. The output signal is applied directly to the driver section inside 1C 3. At the output of that 3C, we find another D1Y transformer and a coupling capacitor to prevent short-circuiting. Resistor R5 serves to adapt the output level to the 5/PDIF standard. Transformer Tf2 is wound on the same type of core and using ihe same wire as Tr 1 . but this time with 20 turns at the primary and 8 turns oi the secondary. The home made transformers are, of course, not necessary if you do not require electrical isolation between the input and output sig- nals. In that case, you may replace Trl with a 1 00-Q resistor between ground and the signal line (directly at the input, i.e., ahead of C3)_ The same applies to Jr2 — this transformer, too, may be replaced by a 1 00-Q resistor to ground. It, too, is con- nected directly to the Input, so in this cose aheod of R5, Note how- ever that R5 then takes a value of 330 f i instead of 470 Q, We would like to odd that this cir- cuit moy also prove useful In a computer environment, some sound cards having an on-board 5/PDIF output that supplies a sig- nal at TIL level. Such a TTL signal may be applied to the D Input of IC3. Components IC2 and C2 are then omitted to add a coax- ial 5/PDIF output fo your f rushy PC. Alternatively the sound card output signal may be applied directly to pin 4 of the TOTXl 73. If you do so, do not forget to con- nect the 3,2-k resistor and the 1 QQ-nF capacitor (R 1 and CT in the diagram]. The reverse applies as well — you can also use the circuit to apply an S/PDIF signal fa the sound card (that is. If it has a TTL compatible input]. In that cose comparer.^ 1C 1 , P 1 C\ or C4, R5 and Tr2 are omitted (for the coaxial and optical input, respectively). The supply section conslsis of a 7805 voltage regulator In its stan- dard configuration. Diode D) not only serves as a reverse polarity protection device if a DC-outpuf battery eliminator is used, but also allows the circuit to be pow- ered from on 8-15 VAC source. Ilf you use (parts of) the circuit in combination with your PC the 5- V supply voltage may af course be 'stolen' from the PC s power supply. This makes the circuit around IC4 unnecessary, except oF course the 1C decoupling capacitors Cl C2 and C5, 3/ 2005 -dd.la rsrtrcnxs 73 kitchen table Quick go/no-go testing for operational amplifiers Dirk Schumacher Not a microcontroller in sight, and yet this item of test equipment will be found very handy in any electronics lab. If you ever want to use an operational amp tiiier salvaged from an old circuit or from, the junk box, you will take into account that the device may no longer work properly. Unioriunaiely, it is not as easy to perform a quick go no-go teat on an operational amplifier using a multimeter as it is with a resistor coil, fuse, diode or even a capacitor. Although an opamp tester would obviously be a useful tiling to have, a dedicated instrument is not easy to come by However, you can build this item of test gear your- self in a few minutes, and it certainly won't break the bank. The test circuit just consists of a sim- ple squarewave oscillator (101) which osciBates with a frequency of about l Hz. The output of the oscillator, on pin 6. therefore sv.ings between highy t [VL,— 0.5 V), and J Iow\ -(V b -0.5 V), with a cenod of about 1 s. fiu Most operational amplifiers come in packages containing one, two or four identical circuits. All the manufactur- ers have standardised on three pinouts, irrespective of the part num- ber of the device. (There are some devices with non-standard pinouts, but they are very rare.) These are shown in the circuit diagram as type 1\ 'type 2' and ’type 3‘, The part num- bers of a few 'general purpose' opamps are also shown. Single and dual opamps come in eight-pin pack- ages, quad opamps in 14-pin pack- ages. All the opamps under test are identically wired, as voltage followers Impedance converters. The output voltage is equal to the voltage at the non-inverting input, and so the squarewave from 1C! will therefore be present on all the relevant pins. The results of the test are displayed using low current LEDs. If the output of the opamp is high, the red LED will light; if the output is low, the yellow LED will light. The opamps under test will need to be able to sink and source a current of at least 2 mA. The test unit Is powered from two 9 V PP3 (6F22) type batteries (BT1 and BT2). D15 and D16 indicate when the supply voltage is present on all the rel- evant pins of the oscillator and of ail the test sockets. As a glance at the printed circuit board layout in Figure 2 will reveal, populating the board should present no difficulties. There are many LEDs, which must all. of course, be fitted the right way around; the same goes for the small electrolytic capacitor and rhe oscillator IG. Don t forget the one wire link, which connects the two parts of the ground plane. It is worth clearly marking the position of pin 1 of the test sockets on the front panel of the enclosure, to ensure that devices under test are never inadvertently inserted incorrectly. Otherwise the opamp being tested will quickly give up the ghost, as you will be able to demonstrate when you subsequently insert it correctly! ,' w r -* 74 ektffonies - 3/3005 LF35E HC4S53 UES&34 QjOH-tt Figure L the circuit can test single , dual and quad opamps . COMPONENTS LIST Resistors: R1-R8 - 3ldl3 R9,R12,R14,R15 = 10k n RIG = 1 OOkQ RU.R13 = 3kQ9 Copoeitors: Cl = IGuF 16V radio] C2,C3 - lOGnF 5 emicondu dors : 01 ,03, 05,07,09, Dll DI3,D15,0i6 - LED, 3mm, yellow, low current 02.04,06,08, D1 0,012,014 - LED, 3 mm, red, low current IC1 = LF356 Miscellaneous: 2 B-way IC socket 1 1 4-way IC socket SI = double-pole on/off switch BT1 &T2 = 9-V battery with clipon connector Enclosure, Hammond type 3 59 IB 1 wire link PCS order code 030386-1 see Readers Services page Figure 2 . The printed circuit board is clearly laid out 3/2005 - efsk lot electronics 75 elektor electronics leading the way Time, Date, Weather Forecast, Humidity, In/Out Temperature and Moon Phase on one display. PICK YOUR OWN ANNUAL SUBSCRIPTION and receive this wireless 433 MHz weather station*! Make your choice: • Elektor Electronics annual subscription (standard) You receive 11 issues, including the July/August double issue. * Elektor Electronics annual subscription-PLUS You receive 11 issues, including the July/August double issue, plus a copy of the Elektor Electronics Volume 2005 CD-ROM (normal price £16,25). Your saving: approx. £10.00! Please fill out the Order Form with this issue. Subscription rates and conditions may be found at the back of this issue. ' Offer available to Subscribers who have not held a Subscription to Elektor Electronics in the Iasi 12 Months. Offer Subject to Availability. refronics 'Edwin' Audio Amplifier (1975) Jan Suiting Blending in beautifully with this month's focus on all things Audio |r d I ihe. to take. v'HL brink, to. Snc l- tember 1975 when Elektor mag- azine published an audio ompli- her named Edwin'. 1975 was the first full year the Englishman- guage version of Elektor was published. Nor surprisingly, the then editors looked at designs that had already proved extremely popular in the Ger- man and Dutch editions of the magazine, which had been on the market for some years already, Edwin' was a beefed- up version of an even older design which 1 have been unable to dig out of the archives. Compared to the earlier design, Edwin doubled the output power from just 20 to a mighty 40 watts (maximum). The huge success of the Edwin publication can be gauged from the resultant PCS sales which, according to some of my older colleagues, achieved many thousands — something we can only dream of In this day and age of DIY audio electronics having taken o very distant back seat to microcontrollers and PC ondllaries. The September 1975 EPS' (Elek- tor Print Service) column lists ihe ' toj ♦, r - n '' hrj/x. h/vuto, r tom .ic. *97-536' ot o price of £1,20 including 25% VAT, excluding 1 5p P&P. IF that strikes you os odd, you need to know that in 1 975 o copy of the magazine would set you back o whole 35p, and a 2N3Q55, 70p, The design of the Edwin would make modern audio amplifier designers either shudder or burst oui laughing. The Edwin power output stage comprised 'workhorse* transistors like the BD 1 38, BD130 and 2N3055, while a 2500-microfarads out- put capacitor was used. The amplifier hod common-or-gar- den small-signai transistors like ihe famous BC107/BC108 in the prestages and worked from o single-rail 42-VDC supply. Two no-load supply voltages were stated. One was 42.5 VDC far 20 watts into 8 ohms, or 34 watts into 4 ohms. The other was 46.5 VDC for 24 watts into 8 ohms, or 42 warts into 4 ohms. These values were given to help readers in the choice of the mains trans- former's secondary voltage — 30 V rm S or 33 V fm5 . The amplifier was claimed to be " ■ifiufji 'fzi. : n, *h rz)r t. huzcli rtc 1 1 ■ f ru types of output stage in one amplifier \ The nitty-gritty was shifting biasing levels of two trannies in the design — depending on the signal level applied, your Edwin would behave as o class-A or a class- B(-ish) amplifier, allegedly with- out running into too much cross- over distortion. The design was advertised as unconditionally stable' and "short-circuit proof , which was certainly revolution- ary at the time. In 1975, no photographs were printed with any of the published designs, probably owing to cost or the poor paper qua hfy. Instead, enticing artist's impres- sions' were drawn by our former colleague Laurent Martin ond printed, in the case of the Edwin, □cross a Full page. The above photograph shows □ stereo ver- sion of the Edwin S found in our lab s relics cabinet. It was built with, in my view, complete disre- gard for electrical safety — note the way the transformer winding was adapted, probably to tweak the secondary voltage. I was not a little amused by the editors first calling Edwin a ,J *7 to/) uzlih f . 1/T ' M ns id! ro design in the Introduction and then concluding the same article with ' Whilst ihe Edwin amplifier meets on excreting specification this is no reason to recommend its construction by the Hi-Fi enthu- siast", which strikes me os much more realistic and modest at the same time. No matter, thousands of readers enjoyed building and using this legendary amplifier! Retronics is a monthly column cod- ing vintage electronics including leg- or.iory Elektcr designs. Contribu- tions, suggestions and request ore welcomed; please send an email to ed E fer^ 3 kta setron i cs . co_ u k . sjhitct: ^stremes EE. 3. 2005 -elektor dtriroma 77 JC1 L .r 6 1 B ■ Martin Ohsmann is a P Electrical Engineering c Technology oi EH Aach time contributor to El eh Through Quizz'oway h stimulating thought , spt construction and si mule raise interesting quesiic Oddball Oscillator This time we present yet another problem covering elementary circuit design. The schematic in Figure 1 shows an opamp circuit supplying a rectangular voltage with o Frequency or about 34 kHz. As a remarkable aspect, components establish- ing positive Feedback and normally required to create oscillation, are not y ■P'f Vf T- ' ofessor of nd Information in and a Iona - or Electronics. = aims ar aviation f tion as well as _ ■ ■ ■ * The photograph in Figure 3 shows the circuit built in flying wire Fashion. The oscillation frequency is so low that para- sitic capacitances, inductances or stray coupling have no effect. This month's question to you all: How does if work? Figure L An oddball oscillator. Up: the circuit mil not function with any oj r a' operational amplifier, but only mSt a '(Btlum kind ', so if nfay he a good idea to get yaw hands on a copy of the LM 6 1 8 1 datasheets ( Uational SBmkcmductori @ +£V Figure 2. Oscillograms produced by the circuit. Figure 3. The oscillator in flying lsad construction. sway mI Quizz't sr to this month s snd win □ ready- Pleose send your answer to this month's Quizz'oway problem, by email, fax or letter to: p.j'v, r i I A. fc+. » . TP"’ .JF .f- . Send in \ne oesf answi Guizz'away question c S. i j i Jt rjo xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx /‘iJ xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx M the September 2004 issue Quizz'owgy rs xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx'xxxxx "he problems to solve are supplied by Professor Martin Ohsrrtann of Aachen Technical University. X X xxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx sure?} (p. /S; Measurements using a probe — never a problem* For V -1 -*■ r- — ■ ■ — I I- Oi — * j “• *" n ■" fi - J i-r «■_-! _» 1 O Ir .-1 t ' - r r % r-S ^ X - * ■_J _ V . . I—' ■_ i_« v M w' v ‘w ■ r ■> " lli . " ere Figure 4 1 t- I - -1 " ■ 'l— r -u.- _• * _■« j-, ir- ^ I *" 1 %_r x-r ■-? I . ' ■_* ’r" f r i ■ ■_■ Figure 5 pi rji r ir L, e; I d 'i ^ 'i.i LJ !l ' r rr J i __l J 1 [LINKS To book your website space contact Huson International Media Tel. 3S 44 (0) 1 932 564999 Fax 0044 (0) 1932 564998 ALLGOOD TECHNOLOGY ivww.a 1 : go odie ch n olo oy.co rn Low-medium volume sub-coniract assembly. SMT specialist since 1990, Customers Include military, aerospace etc. 0402 to BGA capabilities, automatic assembly and hand built prototypes. AUDIOXPRESS www .audioX p re ss .c o m The premier do-it-yourself audio magazine for 35 years, • Hands-on projects • Helpful articles » Expert advice • New technologies audio Full range of books, back issues on CD BETA LAYOUT •' < ww . p c b * pen !xon tag ■ * ■' ■* m — . — — JEST PCO^ODL 1 Beta layout Ltd Award- winning site in both English and German ! M offers protohype RGBs at a fraction of the cost of the usual manufacturers' prices. 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USB INSTRUMENTS http://wvvw. usb-i nstru me nis.com USB instruments specialises in PC based i pr j nr4_i i, ht - j - ... Oscilloscopes, Data Loggers, Logic Anaiaysers which interface to your PC via USB. VIEWCOM http:, .-wwvv. vi ewe o m.i9. c o . u k tel: 020 8471 9338 fax: 020 8552 0946 * Mall Order supplier of: * Integrated Circuits and Components. * Kit and parts for Elektor projects. * Transistors, FETs, Capacitors, Resistors, Crystals, etc and hard to find devices. Viewcom Electronics, 77 Upperton Road West. Plaistovw London El 3 9LT VIRTINS TECHNOLOGY http: 7 www. vfrtins.com PC based virtual Instrument for electronics enthusiasts, students and professionals, including full-fledged sound card real time Oscilloscope. Spectrum, Analyzer and Signal, Generator, Downloader and try. iiLUCTRoraic m^mmmsrs jrf* ere magsre sss E edas arc r- & ewn sb oeera ar^acn .*4 i ft*] : :F .r^rr.j.T;; Contact SuhscriptSwi S ftrtfca 1 ZJ EMI 4 Gibbs fUsd Fsn n, Peste? BsKJ.TScshLrsi T7 lS 7KE Tffc 01 530 200657 Fkx: 01 ^0 2006 1 5 ra uk * 3/2005 AAlcr UrUronks 31 readers services Please Hole fXskEtJEs 3E supped furtne Ef3fT¥cJKTice of t=s£sa wfSiQtA In&net access. READY-BUILT PROJECTS ClariTy 300-W Class-I Amplifier *330217-9 ■ - t=7 e- rord .Mh SVQs pjE-f^tei: c«W fcf LI &L2 Flash Microcontroller Starter Kit 01 023S-9 ' 'S e:/-ee:e~L Ed PCS p ; - i:e-:e - i r= ai=d e/t zee Dameboy Digital Sampling Oscilloscope (GBOSO) 990012-91 ff3dy-as£&m&fed boani r : “E rZ EC^tAfiTe E7i3 lr ££=2 E'l-i tB Micro Webserver with MSC1210 Board GS02S661 '.'ctc-c :?==€• S-is'C I - - ”2 5-9 1 K Etivcr-. &ts he on Sc- inf. ready-as ssmbisd 044 225-92 Corcfr nsJ p* r -e 55 ■0SOB&&-91 & 0-54025-91 4 r&=’« ytsie) EVERGREENS Etekfor Electronics Help Disk 9-55022- ' L>2.„ '.V "C-e.'.e .asla." Elector Electronics Hem Tracer 1965-2003 346226- 1 1 c G“;riE tnzEbas . e •-' = ». Vftndortfs reraton j Universal Prototyping Boards UPSS-1 PC3 UP3S-2 2 FCBs UPBS-4 4 P-CBs No, 341 MARCH 2005 High-End Power Amp 340195-! Arr^rPCB 040155-2 rntfsaafFCB 04 6193-3 Supy v PCS 040195-4 Fuse PCS Dpamp Tester 030355-1 PCS Play Solitaire DIO IT 3-’- Di5>L ET-E^ET EE TERETE 95 04 1 0-4 ? ATS3S 231 3 - 1 2F2 , progrcmrrsd Remole Temperature Logger for PICIflF Board 043441-11 I&v. prI-E -C5? IE _ l "EE nD'i r : . .* = “ - -= £4 La — T : ETE - - 170 -75 E'Z ' :-i“E r E‘ r'ZZZlE - 7; ic : ZEETEd » EfcfiarffeGEnvKS may fcg ixfSfcG using rr 0 ; ar F:~ z--.^: ::::: t " _ t x : . - ?: is Etsaftoontarbwte gxn^ cyStorees orilrf. - 1 t $9 ertirccfc for rn^iij a PC 8 nficJi s Opt ziaS* sfcfe icady-tiBife tte rfesfeas Slices te fEh ,^3 ±. EPROMs yii. : -.4 -Ep-Dt. VACKt =.:si-c nflter ireeraesp.traS'fs &e spppfed fe£tf£pltP ETET-Trrd Pttee E'E ~e — ::e:'ie:'e e_z :z _ _ z zv: T> = E" E'E "I E : ”. E T*: l 7 I " - ‘ T 7 E : : . “7 " ?•■': r ■•"■'te-.--:. Piwsi sr: ft= i sr.ym. Tests i-zunn I’- Jis bi prfTOSi tKues. E- i 0 t 030146-11 Di' s® 3C3£ Otaris i' E I ' 45-4 ■ ATH 5Z3 * 2- ' ’ E F 2 prcg^s “ _ e : PAST ISSUES Paa thrift?. 8 ara^te, sflouM be from VftwWki^ Sets;xi;ti5n Ssrvi^s Ur. Ifs0 4 r C ; '::s Rtri tern, pgihrsy H«i T1CJH11RST TH5 7HE, OjjliA Uf^bons t-r44) 1 550 200557, to (+44) 1530* 2C-:E15. e~A; w>$3hVi Prices of p«l IsetiEE (e.i'CJcpt Aui’/.-Aii^sl &t=q D s£5fT’4>=fj h jndbd^g pasJsjje far sx^ are I- 75 il*' i'c ErE EE 20 i' “ii E-~;e.: Ec "2 l — i : E.'7 'e r "7Tv if :- ; - s r . A.i.it 1~C Lr7E“7r :E5_ = £ “7 _7 ':Z 3I7:2IE fs i “7 E CJTpEE, ats £5.05 ilK Erd E^e); D.35 &jrtp£}7 2nd £845 (^tin£l Ot^adfe £mopE) . PAST ARTICLES ; . -Jjjj E rT_ ; ;,= ; : :ir.: GCr*J[l I-' Ec’T'I^e E r : .-z ~ ' eeeei: OTi-s (31580) 200557; to 200513. zmTi i { 77E' 7 : 77 j £ OSS 4-SO fl.65 7-40 13.10 No. 335 SEPTEMBER 2004 B 45 1445 Railing Dice 04024 B -1 F'C 3 SE 7 : 5 - sifes 13-75 24.30 S ‘15 14.35 ■D 402 -S 8 * 1 1 D dJ Evirce i ' t c t T-e e 4-99 S 55 D 4 D 2 J 8-41 AT 39 C 2151 - 12 P e-^eth S j 7 u 245 AM Swiss Army Knife 4 ID 7.25 039445-1 PC 3 EEL- V£'j. RS 232 L =5 950 ‘5 E 'J fc-^a 1 L 55 010443 -H LE'EET E-E. E 77 E^E .77 EETT.'iL'E 5-53 ' 1.50 0304 45 -n 475955252 - 24 = I : ■ . ; -j - - e 7 25 - 5-5 - 5.75 No. 334 JULY/AUGUST 2004 e-io is.ao IR Servo Motor Interface e -70 1 Z 50 020356-11 Disk. RGX praoirzm and PSC soiree S eb§ec? code 4-00 555 6 ’rtJ 12.60 92235 - 5-41 ?; I ' 5 : 521 . prec^TJUsd io m 77 70 3 - 7 a 7.10 52 - 21 . 55-42 F rC 1 £7525 prcc'iT.-Ed itMje 17.70 Micro Webserver with MS Cl 21 D Board 3-55 1045 04452S-1 1 .t 7 Ei t =;e :^ B:e*e =21 c-5'y 10-45 15 53 R/C Analyser a* 2 U 9.75 03 - 01 76-11 C&: D S=:_-.r :; ;e 4-99 5.55 4 -£?J B. 6 g D 30173 - 4 ' 1 l€ 15 552 7-4 CP :-::'etj _ 7 : 10-25 IS 15 USB Converter Conlrailed via HTML 3-25 9./5 044034 - 1 1 C's:.. EfET :• e i.te 4 -SQ 5 55 Working wilh AcliveX 5-29 9 .f 5 03 S 43 T -1 1 C' 7 - 4-90 3 55 No, 340 FEBRUARY 2005 No. 333 JUNE 2004 RFIO Dctedor for 13.56 MHz Multi Programmer 040299-1 PCs 9m 18-03 D 2033c- 1 PC 5 fi-SO IS. 60 Walking Bug G2 03-36' 1 1 D :.;>L f r -T a -g* i e : let e. = cece 4-20 9.55 040071-11 EK&scufijc & hex Ctt& fifes 5’70 10.59 Pockel Pong 040^371-41 ■'“92522' 5-1 Q=; 1640 030320*11 De- P,c s^lve-t 4-SG 3.65 No* 339 JANUARY 2005 Rail Router 030403-1 723 1650 19J5 ATX Power Supply Tester C 5 2- 22-11 Uzk.Fi C £ PC ect;, eje 4*9C 8.65 0401124 FC0 11-85 21. CO j 3Q403-4 - p£ ‘ e F877 • Z 7 ?. pr eg - < Ttmee 2145 37.95 Intelligenl Clap Switch Smooth Operator 03215C-- PZB 5-29 14.J0 025203-11 0 is v FiCseft^/se 4*90 5 55 HZ' 5-5-1 * sXs ‘ E7,rc:i--i> r :; 4-9*0 5.65 030209-41 ;F □ 1 c FB 4-1 “ = pmoam-Tied 14*70 2600 2 301 55-i - =712752927 program-raf GM 1120 PIC1BF Devetopmenl Board No. 332 MAY 2004 Q4DG10-1 PCS 10 1930 Design Your Own EC 000365-3 7CB C4Q0 ' C- IT De 1 . ei Tt i'j e t e iit ~ee 459 B.d5 15-65 27 7Q No* 338 DECEMBER 2004 High-End Preamp 6 45 14 95 020040-1 PlB — TTEEiri bosid 1 C Home Bus 02004^2 FCB — recEy toard 7-5-3 3 22 ~ 040333-1 F-ca 12-10 21.40 02(3046*3 PC3 — PSD board 5-70 11,05 C4S333-1 1 ffiE- 5C-LSE5 St !- E J . ES4i t-fss 4S0 8,65 020046-1 1 G.e< 490 Z 5-5 LED Christmas Tree 02064641 Pffi18t_F452*tL pr-eoeaflmtf 2520 49 90 D 15-24 §-91 fffiefFCBapsts e-25 11.00 Wind Speed a Direction Meier USB l_C Interface D3037 1-11 0 e 7 prc.EZt sgtua 4-90 3.65 0403344* F€B 1-03 *3 50 030371-41 PSC 16^7 1. pfog#snfr^ 17-55 270-5 -40534*“ D4V S*'C;f7 ::^.r45 4-9C 8.65 0^9334-21 24LC54 pmsfsmmcC 4'5‘j 3 50 No. 331 APRii 2004 No. 337 NOVEMBER 2004 Drop'in Microoontrolier Board 026149-1 FT 5 8-60 1550 iioise Suppression Filters 020 ’ 45-1 1 JKsk, sans ' e profed f . 2 4‘50 S.t5 03D217-3 PCS 13-35 23 .S3 VHP' Low Eiplnrer Vehicle BattEry Jagger 02£4‘61 PCS 3 80 15.30 044921-1 PCS £75 1135 No. 330 MARCH 2004 No, 336 OCTOBER 2004 Build Your Own QRM Receiver CianTy 3QCLW ClassT Amplifier 030365-1 PCS 910 16.10 030217-2 RGB 1 5-90 25.10 0 30365* 7 1 Oil *: a H V f ‘i : 'C7 m m 4*90 3i3 Four In a Row Code Lock 5 321 47-7 PC 3 1345 2315 n5C434*i PC-B 660 16.95 82 ^ : E'.fcr - 3/2005 £ USS us s 020434-1 1 Disk . Sdurtti a hat cotte fifes 4-5D E 65 02043441 F , jc16fS4A-ip' programme! '4 70 26 AC Hands-on CPLOs (2j 03S032-1 PC 3 fi-93 15.75 03GQ52-11 Software 4-90 6.55 036652*41 EPfc5712£SLC84-15, pfe^Tarnmed 33-40 59.10 Multichannel Failsafe for Radio Conlrolled Models 1 Dak. SOitfCS Cuds fite -4*20 8.65 G203SuMl AJ89G5224J, pracpanined 6-70 15.40 Multifunction Frequency Meter 0301 ££-1 PCS S-S5 ^6-55 030136-1 1 ftsfc. prefect software 4-95} S.65 03Q13WT i09OSZ3f3-1O?C H procr^raneti 7-95 14. 05- No. 329 FEBRUARY 2004 Digilal Alarm Clock 03059641 [>4Jc PIC :oute£ and tec cotfe 4-90 S.S5 030095*41 RfCl6?34-04p, tsfog^fTT^d 15*20 26,90 [Access OX-j 165-it C&L set so tan crate and tsi^csi soft a ire 7-50 1 330 02O163-41 AT89SS252-I2FS. procrarrened 13-90 24.60 Simple 12*10 -230V Power Inverter 020435*1 PCS 3*0 15.05 Touch- controlled Switch 030214-11 Dsfc P-C st»40^ code 430 555 050214-11 F.C12C508AS4.S03. pTC^^T-rrssd 6*15 10.90 No. 32 B JANUARY 2004 G4-K 6QC552 Flash Board 030042-1 PCS 935 16.55 030042-11 Disk. rT^iC. proper software 4-90 8.65 030042-21 29FQ10. Eii^mTBd HHK 17.70 038042-31 GAL 16V643150?* prograrmtted 6-10 la.so ClJmaie Logger 030075-1 PCS 7-75 13.70 038O7&-11 Disk VAndoirs software 4-SO E.65 FMS fltghl Simulator Encoder 03OO66-1 PG6 10-2O 18.03 030066-41 S7LPC7678!;. F«cgg2nun=d 17-05 33.15 LED Roulette 030168-1 PG3 17^50 31.60 G 30163-11 Dr sk e d tree "d ' pi f- ® 4-90 8.65 0301 68-4 1 KJC2051-T2PG, programmed 8-05 1 4 25 Multi-event Alarm Clock 020304-11 Disk, C (some) tex f;r~3 4*® 8.65 G20334-41 AI89C2651-12PC, prc^fiTEfT5Kl 5-ID 1 0&4J Stepper Motors Uncovered 020127-41 P1C16F873-2Q5P 1^10 33^0 No, 327 DIC EMBER 2003 FM Remote Conlral Transmitter & Receiver 034044-1 PCS J0-20 13,65 LED Christmas Decoration 830157-1 PCS 7-55 13.35 PB7LPC76x Programmer 030313-11 Oefc. prpfKl soJt#raB 4-95 3.65 Project Timekeeper 020350*11 Dfefr, smi^e 8 e&^ct Ses 4-9u 5 .55 02035CM1 PiCl£FS-P'Q.R progrsnmsd 13-15 23.25 Stepper Motors Uncovered (2) O20127-11 fKsk, source cafe ffe 4-90 6.65 Universal Clock Generator 020395-11 DsX source code fe 4 24 3.55 Wireless RS232 Link 039204-1 PCS 8*70 15.40 No. 326 NOVEMBER 2003 Precisian Measurement Cenlral tmm* PCS 37B 1540 No, 326 NOVEMBER 2003 Rev Counter for R. C Models 024111-1 PCB 1750 31.00 024111- n soute snd hex crate 4 -sd a. 65 Q 241 T 1-41 BSC2051-12PC programmed 5-E5 15.65 Running Texl Display 02O4O7-11 [>4i. source and hex cote 4-&3 6.65 USE Analogue Converter 02O3 i 4-1 ^CS 7-65 13-50 020374-11 hex code and W 4-90 8 65 025374-41 PJ016C765. programmed 13-25 23.45 Xilimc PROM Programmer 010103-11 Software 4-90 5.65 No. 324 SEPTEMBER 2003 AIV Picture Generator C2 0295-11 D-.t- &■>_“ 5 i ft =« : :•:= f ^3 4*90 S .65 02G29a-41 AT90SBS15-SP0 t pnsg^-mned 15 20 26.90 020295-42 AT 90S1 200-1 2PC. 13-^ 24.6*0 OTMF Remote Telephone Switch 020234-1 FC3 11*65 20.60 02 0294-11 £ ;e«l ps> =•:: softy.- = ?e 4-90 5.55 0202 9-4-41 rvCTtFS4A-20 P 14-70 20.00 LC Display with 1 C Bus 033060-2 PCB 7-35 13 DC- PlCPiog 2003 01Q2O2-1 F£ 3 9-D5 1 5.00 010202-11 Osk. Win&rws software 4-93 3.55 010202-41 FrCl 57.574-20 F. pr^rsrr msi 23-55 41.65 Polyphonic Doorbell £2“5 54-11 DO> z-z-zzt softiv l~e 4-90 S 65 0203^4-41 RCtffB4A- ■.■ *‘ £ l*. 'I ' ■ : _ 14 45 2555 Precision Measurement Central B30O6CP9! 0^.=if_,--zE-i3Tijj'arj ^ tsiEd baanJ mm 112.56 Valve Preamplifier (t) £-208*3-1 FCE 1 1 1-5-5 20.4-3 020355-2 PCS. powsr 1140 20 20 020233-3 PCB tOboaM 10 ID 17 99 No. 323 JULY/AUGUST 2003 Add a Sparkle £25293-1 ■ Disk. HEX iid V. stz ffes 4190 3.65 02? 293-41 Fi C 1 2C522A-D4 S \t p*zq ‘rr - ts 7-4D 13 10 AT9DS2313 Programmer 034035-1 F£B M5 16.0D Mint Running Text Display 02 i 2 55-1 1 test sECsce c ->3e £ e 4*90 5.55 Mini TesI Chart Generator 02 £403-11 Hfe" PfC EKi^s cods 4-90 E55 Programming Tan! far ATtinyl 5 mm~-t pcs 7-55 03'-? 3 jQ-l ' _ - ■ ■■"v 1 jfiAiTr 4-&D 5 53 Quad Bridge Car Amp G340]9-1 PC3 8-70 15 £5 Remote Lighl Contra] with Dimmer 029337-11 I s* -EX 5T.d ®ss 4-93 5 65 02 1 237-4 \ i“ 69 C 2 C 5 : -1 2 : : 6 25 T1.05 No. 322 JUNE 2003 AVR TV Tennis 030025-1 Vars PCS £-70 15.40 lhl'jZc-Z PCS 5-EO 1525 L 3 Z'J 26-7 " C ;=* AVR ss;:?.-: 4 [ CCf 4-^3 : 35 £3-02 £■- • 4734 = Si 5 . pnKjrLT. 7^2 15-29 2622 Eleclronic Knotted Handkerchief 020 358-11 D4.V PC t r $ c m* z r ECtrr, 4-90 3 65 02830^41 AT9D53S13’1C?C ~z~ 12*60 22.30 Law-Cost LCD Ccnlroiler (2) 0201 W FCB £-70 15.35 620114-11 Disk preset sotrmfE 4-9G 3 65 tlrght Ligh! Contra] 0201 " 5-i 1 DXV ?£.*. i' i v 1 JC z code 4-90 8.65 020115*41 AT90S2313-1tM; T pfogr2rm5=d 12S5 2275 Universal XA Devetopmenl Board oi 0103-1 pea 13-20 23 35 610103-1 1 Disk GAL :c:-t EPRC.M fra ff es XAKv 1- 4 SO 3.6-5 G 1 u 1 03-2.1 5FRCV £5. 27CZ56-9D H&yznzisa 1003 17.70 01 0 1 03-22 EPROLt O t 27C25S-90 r pro^aJi^ed 1003 17.70 01 01 03-3 1 uAL ' : ■ : p/QCiSrirnaJ 4S0 3 5-3 No, 321 MAY 2003 Countdown Timer Q2023S-': D.ii: s : _ - : e ej? d r.-=A c ate 4-90 : 55 1 252 2 5-* 1 AT5 25 1 2£-j . pfogrsn* -± : 13*50 24 GO USB Audio Recorder Dl25l3-n £;- EFROlt ra K-as 4-50 z 65 01201 3-2 1 EWQ V 2 7651 2_ p::*- -- 12-60 22 30 No. 325 OCTOBER 2003 ODS RF Signal Generator 123299*2 PC E el:: , 12-10 21 .46 020299-41 AT90S&515 BPC, progsiMiiad Mlnimalis! Induction-Balance Metal Delector 3cj-55 54.66 O2O290-1 fcb S-95 15.26 Valve Final Amp |2| 020071-2 Pmr^spppiy board 1(HK 17.75 3 2005 - Viktor e'sefrenris 33 snealt preview LPC21 Ox 'ARMee' Development System (2) Having digested the background article on ARM processors in the March 2005 issue you're ready to proceed with an ARM development board that follows in the footsteps of illus- trious predecessors like cur TICee and 'AVRee' systems. A special feature of the project is the transportability (literally) af the ARM CPU sub-board — once programmed on the development system it can be unplugged from and migrated to a target application. Tony Dixon has the full story. USB-GFS Unfortunately this article could not be included in the current issue due to lack of space. It describes an inter- face between navigation applications and a miniature GPS module coupled to an equally small active antenna. The modular structure of the project allows you to use selected parts for your ovm applications. Serai conductor Ffialyser Ml, He J * * V^fcfcViSS L ^ r P . , .. , p. *? SC-Anafyser Transistors are found in lots of electronic circuits- However, as many a repair engineer will avow, these components are not always easy to identify, which makes checking them — and finding a spare or substitute — a bit of a problem. Our Semiconductor Analyser Is not only able to discriminate between FETs and bipolar transistors, but also snoop the pinout and extract the main electrical parameters like from an unknown device. Theme Plan for 2003 January .... .Power Supplies February . , „ .Wireless March . , . . . .Sound April . . .... .Microcontrollers * May ...... .Sensors June ...... .Environment july/August . .Summer Circuits September . , Jest & Measurement October .... Security November . . .CAD Software December . . .Optoelectronics Also.,, Long Lines in Chips; Delphi Course (4); Simple LiPo Charger; 27C5I2 Emulator; The Digital Future. RESERVE YOUR COPY HOW! Tb April 2005 Blue m * cn mb cn Safwddcy 19 Alardi 2005 (UK dstinbulrcn only). UK subscribers mil receive the magazine o fe> days before this dale. Mde tilbs and magazine sontenls syisjsci to change. NEWSAGENTS ORDER FORM SHOP SAVE / HOME DELIVERY Please save / deliver one copy of Elektor Electronics magazine for me each month Name: Address: Post code: Telephone: Date: Signature: * * * ¥ ■ -S 1 ■ » # S' ■ ■ d *■ 1 lectronics Please cut out or photocopy this form, com- plete details and hand to your newsagent. Elektor Electronics is published on the third Friday of each month, except in July. Distribution S.O.R. by Seymour (NS). Index of Advertisers All good Technology. Net links . . A shJi oppress, Net Links . Ssia Layout. Net Links aom lEchnotogy LTD. rj-et Links . . 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Student applications, who qualify tor a 20" □ (twenty per cent,* reduction in current rates, must bs supported ire evidence of studentship signed by the head cl toe college, school or university faculty, A standard Student Subscription costs £31 .60, a Student Subscription-Plus costs £37.60 (UK only). Please rote that nev: subscriptions take about four weeks from receipt of order to become effective. Cancelled subscriptions will be subject to a charge of 25% (twenty- five per cent) of the full subscription price or £7.50, whichever is the higher, plus the cost of any issues already dispatched. Subsciptions cannot ere. cancel -A after they have run ter six months :r more. January 2005 Modern High-end Valve Amplifiers CD-ROM Audio Collection 2 A unique CD-ROM for the true audio lover, containing no fewer than 75 audio designs from the past five year volumes of eJektor electronics magazine. The articles on the CD-ROM cover test & measurement equipment, amplifiers, digital audio and loudspeaker technology. Highlights include the Crescendo Millennium Edition, Audro-DAC 2000, Audio-ADC 2000 and the IR-S/PDiF Transmitter and Receiver. Using the included Acrobat Reader you are able to browse the articles on your computer, as well as print texts, circuit diagrams and PCS layouts. £12.05 [U5S 21.25) Also available: Volume 1: More than 75 audio circuits from the 1996-1999 volumes of EJektor Electronics magazine £12,05 (USS21.25) 2x300W Amplifier board with SMDs pre-fitted Vatve amplifiers are regarded by many to be the ne plus ultra when it comes to processing audio signals. The combination of classical technology and modem com- ponents has resulted in a revival of the valve amplifier. The use of toroidal-core output transformers, develo- ped oy the author over the past 15 years, has contri- buted to this revival. This book explains the whys and wherefores of toroidal output transformers at various technical levels and offers innovative solutions for achieving perfect audio quality. ISBN 0 905705 63 7 * 264 Pages * 25,95 (US$52,00) 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 will not pay these high prices, there is a solution offered in this book: build your own at considera- ble 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 crossover filters, an active subwoofer, a head- phone amplifier and more, ISBN 0 905705 40 8 • 262 Pages • £15.55 (US$3 TOO) Elektor Electronics (Publishing) P.O. Box 190 Tunbridge Weils TN5 7WY ENGLAND Telephone *44 (0) 1580 200 657 Fax *44 (0) 1 580 200 61 6 Email: sa!es@e1 ektor-electron I cs.co.uk RRP £34.50 (US$ 55.70) This top-end amplifier proves that high power does not have to mean a large, heavy design. Although this amplifier is highly efficient (and thus compact), its spe- cifications easily surpass those of quite a few conven- tional designs. i his 2 x 300 watt amplifier board has modest dimen- sions thanks to the use of SMD parts fitted at the underside. Elektor Electronics greatly simplifies building this project by offering the stereo amplifier board with all SMD parts already mounted, for just £34.50 (or USS55.70)! Also included are the two toroid cores for the output filters. More information on this powerhouse may be found in the June and September 2004 issues of Elektor Electronics magazine. Build your own Audio Valve Amplifiers To many people, the thermionic valve or electron tube is history. However, whether it is nostalgia, interest in the technical parameters, the appeal of a gleaming amplifier chassis with softly glowing val- ves or perhaps the firm conviction that the sound of a valve cannot be bettered, it is a fact that the valve is making a come-back. This book contains, apart from construction projects for preamplifiers, power ampli- fiers, and amplifiers for musical instruments, information on the operation of electron tubes, while the first chapter gives a short history of the valve, ISBN 0 905705 39 4 * 253 Pages * £15.55 (US531.G0) Order now using the Order Form in the Readers Services section in this issue. More information on www.eiektor-electronics.co.uk AllDBS© 1©@KS Powerful & flexible schematic capture. Auto-component placement and rip-up/retry PCB routing Polygonal gridless ground planes. Libraries of over 8000 schematic and 1000 PCB parts. Bill of materials, DRC reports and much more. Berkeley SPICE3F5 simulator with custom extensions for true mixed mode and interactive simulation. 6 virtual instruments and 14 graph based analysis types. 6000 models including TTL, CMOS and PLD digital parts Fully compatible with manufacturers’ SPICE models. Supports PIC, AVR, 8051, and BASIC STAMP micro-controllers. Co-simulate target firmware with your hardware design. Includes interactive peripheral models for LED and LCD displays switches, keypads, virtual terminal and much, much more. Compatible with popular compilers and assemblers from Microchip, Crownhill, IAR, Keil, and others. www.labcenter. co. uli info@labcenter.co . uli Simulation Auto Routing Schematic & PCB Layout • Textual library part search. • User defined keyboard map. • CADCAM output to ZIP file. • Bitmap import function. • Truetype fonts on PCBs. • Enhanced printer output. Call Now for Upgrade Pricing Mixed Mode SPICE Circuit Simulation Proteus VSM - Co -simulation and debugging for popular Micro-controllers NEW si r - r * | 3 - •» I ■H j " ~ (l m \ F J i . r , JjjL TTT j -f