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BONUS DICK SMITH ELECTRONICS CATALOG ~- - AUSTRALIA'S LEADING i ~~== ELECTRONICS MAGAZINE_ r-iiiiiiiiiiiir-iiiiiiiiiiii~r---=- SERVICING -VINTAGE RADIO - COMPUTERS - AMATEUR RADIO - PROJECTS Build This 4-Digit Capacitance Meter Measures from 1 pF to 9999µF Using Your PC As A Function Generator DIGITAL CAPACITANCE METER ◄ ui 0 0. ,._ ., ""' ·- iii 0 a, .:: 0. ::, zIll < 0 ~z II> ~ - ... .2 Cl) ., -1/1 ·c.> ·5, :c Cl)::, a: 0. * The Mozzie CW Transceiver * High Energy Ignition For Cars With Reluctor Distributors * Electronic Load Box For Checking Power Supplies 3.5 " D.S.D.D. COMPUTER DISKS David Reid Elettronits PKT 101 , , NOW ONLY $19.95 ,. BULK PURCHASE (100 DISKS) FOR $140.00 . I two heads and the butane gas torch itself. NOW ONLY IBM PRINTER CABLES LAST CHANCE AT THIS PRICE $8.00 ea COAXIAL CABLE CRIMP TOOL • Insulated handles with spring ret urn . • Push to release butto n. • Jaw sizes: 1. 72, 2.5mm for inner conductor crimp pms • Jaw sizes: 5.4, 6.4 8 and 8.2mm for shielding crimp co llars • Length: 22 6mm ONLY $59 .95 $69.95 ONLY $22.95 IEC 320 EXTENSION CABLE VIDEO TRANSMITTER AVS30 Output Chann el: UHF channel 30 Tuning Range: UHF from 512 to 612MHz Transmitting Distance: 10 metres RF Output Level: Below 500uV/M at 30 metres Antenna Imp: 75 ohm. Power: 2 watts. Video Input: 0.8Vp-p to 2Vp-p. Audio FM Deviaton: Max. 40kHz. DB-25 PLUG to CENTRONICS PLUG 1.8MTR LONG NOW ONLY ONLY IEC LINE MALE PLUG to IEC LI NE FEMALE SOCKET ·LENGTH : 2 METERS ASSORTED PRINTED CIRCUIT BOARDS MINI VAC CLEANER Double Sided Boards 335mm x 120mm 505mm x 205mm 605mm x 120mm Single Sided Boards 305mm x 11 0mm 31 0mm x 185mm 335mm x 100mm FOR DELICATE DUSTING Ideal for cl eaning mod el train layou ts, tiny PC boards, or hard to get at el ectronic equipment. Also good fo r camera or computer equip. $350.00 INCL. POWER SUPPLY Oty Avail Price 75 113 23 S3 .&5ea 200 s~ ooe2 37 5mmx 90mm 405rtun x 95mm 405mm x 110mm 405mm x 170mm 505mmx 90mm 505mm x 105mm 505mm x 110mm "PHAXswitch" $299.00 $16.00 ea HURRY!!! LIMITED STOCKS $14.95 NORMAL R.R.P. S-4 SOea S3.45ea 24 20 60 30 40 30 45 S315ea S3 i 5ea S3..! Sea S3. t 5ea NOW ONLY S3 .8 5ea S3 .45ea S3. SOea 55 S3.60ea $140.00 "XITEL" XM-12E MODEM • • • CCITT V.2 2 (B,ii) (1200 bps) and W. 2 1 (300 bps) Bell 21 2 A (1200 bps) and 103 (3 00 bps) Asynchronous • Auto-Di sconnect • Full duplex • Tone and Pulse dialling • • Auto-Dial Auto-An sw er • • Call pro gress monitoring Loopback for remote diagnostics • • • Internal speaker with manual and software volume con trol 8 status and activity indicators Communicate via RS23 2 port. WAS $299.00 NOW ONLY ONLY $199.95 $150.00 $199.00 LABTECH 20MHz 2ch CRO with COMPONENT TESTER • • • • • • $775.00 ULTRA-SONIC CLEANER ONLY SCOOP PURCHASE 65 • Ideal for cleaning drafting pens, watches , photographic filters , or even dentures. • 240 volt operation. 200 WATT BABY AT POWER SUPPLY SS .95ea STANDARD "AX 700" WIDE BAND COMMUNICATION RECEIVER Frequency range: 50 to 904 .99 5 MHz. Radio Wave Formats: A3E(AM), F3E(FM-WIOE, FM-N ARROW). Frequency Steps: 1OkHz, 12.5kHz, 20kHz, 25kHz (AJ MODE: 5kHz, 1kHz with up/down keys) Number of mem ory channels: 100 channels. Number of program search memory locations: ~ 0 locations. Reception sensitivity: Am (1OdB S/N): Less than 3uV FM-N (12dB Sinad): Less than 1.5uV FM- W (1 2dB Sinad): Less than 1uV (83MHz) Squelch Sensitivity (FM-N Mode): Less than 0.2 uV Audio Outputs: Ext speaker jack, more than 1.8W (BIOhm, distortion 10%, input FM 1kHz 3.5kH z DEV) Record Jack: 30mV (load 1OOK Ohms) Dimensions: 1BO(W) x 75(H) x 180(0)mm COMPLETE WITH POWER SUPPLY AND ANTENNA ONLY $899.00 Two external lenses designed to suit video cameras. One is a " 1.6 x teleco nvertor" which increases the focal length by 1 .6 times. The other lens supplied is a "0 .5 x wide angle converter" w hich decreases the focal length by half. • Multitap: 1 2V <at> 5A 15V <at> 4A 24V <at> 2 .5A 2 7V <at> 2.2A 30V <at> 2A • 240 volt PRIMARY $89.95 The PHAXswitch is an automatic switch that allows to run a phone and a fax on one telephone line. • Three (3) operation modes: automatic phone/fax selection manual fax; manual phone • PHAXswitch answers an incoming call (silently) , decides if the incoming call is for \ the phone or the fax, automatically puts it through to the correct unit, and ring s the ' phone or fax as usual ' ' NOW ONLY 3 PHILIPS + 3 FLAT HEAD FROM 165mm to 240mm LONG Set of high quality Nickel Chrome Steel Screwdrivers . Extra long shafts and handles allow use in difficult situations. Complete tool kit designed around a hand-h eld butane gas·to rch. Supplied wit h a roll of 1 mm solder , tip cleaning tray , slx so ldering tips, hot knife, flat flame thrower , penc il flam e thrower , PKT 10 NOW ONLY $6.45 BULK PURCHASE (100 DISKS) FOR $60.00 ONLY $87.99 6-PIECE SCREWDRIVER SET " VULCAN " GAS SOLDERING IRON KIT 5.25 " D.S.D.D. COMPUTER IDISKS UP604 IBM BREADBOARD CARD See Re view in Silicon Chip November 89. Accomm od ates up to 24 14-pin ICs. Includes 0825 femal e socket for external connections. Suits AT/X or compatibles. INCL TAX Deflection Factor: 5mV to 20VIDIV on 12 Ranges. Operating Modes: CH-A, CH-B, DUAL and ADO. Sweep Time: 0.2us to 0.5s/DI V on 20 Ranges. Source: INT CH·B, LINE, or EXT. Includes 2 x 1:1 & 10:1 pro bes 12 months Warranty. PLUS RECEIVE FREE: A 3.5 DIGIT MULTI METER WORTH $57.00 (EXTENDED FOR MAY) POCKET SIZED AUDIO SIGNAL GENERATOR Now you can have a lull fu nction audio signal generator tor less than S100! 46 preset switched frequencies from 20Hz to 150kHz. Frequ ency Range: X 1 rang e 20Hz to 1.5kHz x 100 range 2kHz to 150kHz, both ranges are selectable via 23 sel ected ranges . Output Control: OdB, - 20dB plus fi ne adjuster. Output Impedance: 600 Ohm + /· 10%. Sine Wave: 1.2V rms maximum Square Wave: BV P·P maximum ONLY $99.50 Rise and Fall Time: Less than 5 us Carry Case $12.50 ~ PHONE NOW!!! (02) 267-1385 TO PLACE YOUR ORDER MAIL ORDERS POST & PACK BUSINESS HOURS 127 York Street P.O. BOX 0103 S5·$25 .... S4 Mon-Fri 8.30-5.30 David Reid SYDNEY 2000 ........ VISA SYDNEY 2000 $26-$50 . . . $5 Thur 8.30-7 .00 Electronics Ph: (02) 267 1385 FAX: (02) 261 8905 S51+ ... . . SB Sat 9.00-1.00 -~ ~--- ~ ----"==- -- - .,,,,. MAY 1990 THIS 4-DIGIT CAPACITANCE meter is easy to build and can measure capacitors from 1pF to 9999µF. Construction starts on page 20. FEATURES 4 Error Correction For Digital Recordings from Philips Promising new technique fills in the gaps 16 Fingerscan Personal Identification by Leo Simpson Will it make ID cards obsolete? 92 Waveform Generation Using A PC, Pt.3 by Steve Payor Tone burst and function generator software listings PROJECTS TO BUILD 18 High Energy Ignition For Reluctor Pickups by Uses the Motorola MC3334P ignition IC J. Clarke 30 Build A 4-Digit Capacitance Meter by Greg Swain Measures capacitance from 1pF to 9999µF 48 16-Channel Mixing Desk, Pt.4 by John Clarke Testing the equaliser/VU board & chassis wiring 66 The Mozzie CW Transceiver by Clive Chamberlain Easy-to-build low power design SPECIAL COLUMNS 8 Vintage Radio by John Hill Cleaning up the chassis 42 Amateur Radio by Garry Cratt Electronic load for checking power supplies LOOKING FOR AN ignition module to go with reluctor-style distributors? Our latest ignition module can be used with all sorts of reluctor distributors, including those in Mitsubishi Sigmas. Details page 18. Dick Smith Electronics Catalog THE BONUS CATALOG from Dick Smith Electronics has been inserted in all issues on sale in Australia. New Zealand readers should not feel left out though. The June issue of SILICON CHIP will include the Dick Smith Electronics catalog for New Zealand. 60 Serviceman's Log by the TV serviceman Something old & something new 74 Remote Control by Bob Young Aerodynamics & stall conditions 82 Computer Bits by Jennifer Bonnitcha What to do when your computer goes bung DEPARTMENTS 2 Publisher's Letter 3 Mailbag 14 Circuit Notebook 86 Product Showcase 98 Back Issues 100 101 102 104 Ask Silicon Chip Notes & Errata Market Centre Subscription Page THIS NIFTY LITTLE transceiver is suitable for Morse & RTTY and puts out about 1W at 3.5MHz. We show you how to build it starting page 66. MAY 1990 1 SILICON CHIP Publisher & Editor-In-Chief Leo Simpson, B.Bus. Editor Greg Swain, B.Sc.(Hons .) Technical Staff John Clarke, B.E.(Elec.) Robert Flynn Advertising Manager Paul Buchtmann (02) 982 9553 Regular Contributors Bryan Maher, M.E . B.Sc. Jim Yalden, VK2YGY Garry Cratt, VK2YBX Jim Lawler, MTETIA John Hill Jennifer Bonnitcha, B.A. Bob Young Photography Bob Donaldson Editorial Advisory Panel Philip Watson, MIREE, VK2ZPW Norman Marks Steve Payor, B.Sc., B.E. SILICON CHIP is published 1 2 times a year by Silicon Chip Publications Pty Ltd. All material copyright (c). No part of the contents of this publication may be reproduced without prior written consent of the publisher. Kitset suppliers may not photostat articles without written permission of the publisher. Typesetting/makeup: Magazine Printers Pty Ltd, Rozelle , NSW 2039. Printing: Macquarie Publications Ltd, Dubbo, NSW 2830. Distribution: Network Distribution Company. Subscription rates: currently $42 per year (12 issues) inside Australia. For overseas rates, refer to the subscription page in this issue. Liability: Devices or circuits described in SILICON CHIP may be covered by patents. SILICON CHIP disclaims any liability for the infringement of such patents by the manufacturing or selling of any such equipment. Address all mail to: Silicon Chip Publications Pty Ltd, PO Box 139 , Collaroy Beach , NSW 2097 . Phone (02) 982 3935 . Fax (02) 982 9553. ISSN 1030-2662 2 SILICON CHIP PUBUSHER'S LETTER Power lines and the environment: a touchy subject During the month of March, the ABC program "Countrywide" had a segment about a rural community in New South Wales protesting about high voltage power lines crossing their land. Now this subject has been discussed to some extent in the June 1989 issue of SILICON CHIP and my attitude in the past has been to dismiss most claims about the effects of power lines on human beings. But the power lines in the Countrywide program were of a totally different magnitude and I couldn't help feeling some sympathy for the protesters. Forget the whacky claims made about power lines in the past which have generally been concerned with voltages of up to lOOkV AC or more. It is difficult to conceive that these have any biological effects or if they do, they must be very small. But what if the voltage on the power lines is 600,000 volts AC and the current is thousands of amps? What if the voltage gradient is high enough to light up fluorescent lamp tubes carried by people walking under those power lines? What if you are a farmer cultivating crops every day with those power lines passing overhead? Wouldn't you feel just a trifle edgy? I know I would. Apart from the dangers, real, imagined or unquantified, who really wants those monstrous gantries marching across the landscape, especially if you own the land? And I can think of a third reason why the farmers would not want those extremely high voltage power lines close by. Think of the effect they could have on TV and radio reception. Corona discharge at 600,000 volts AC is a dandy of a problem. That's why you see very high voltage cables hanging in pairs or groups of three or four - it simulates a much larger cable diameter and thereby cuts down corona discharge. No, the more I think about it, the more I am sympathetic to the farmers. We all need electrical energy but maybe the real cost of transmitting it at such extreme voltages is just too high. Maybe the time has come when such high voltages are no longer politically acceptable. Maybe we should accept the slightly higher losses of transmitting electrical energy at lower voltages and then put the power lines underground. It is not cheap or easy but it has been done before. In the future there is no doubt that all large engineering projects will be subjected to much greater scrutiny with regard to their effect on the environment, on people's health and well-being, and on safety. High voltage transmission lines certainly come into this category and if they are subject to much closer questioning, then that is probably a good thing. Leo Simpson MAILBAG Wants articles for the Amiga computer I am pleased that SILICON CHIP has started a computer column. It's all very interesting but although the IBM compatible PC may be the business standard, it is not very popular as a home computer unless you use one at work and need access at home. I believe figures would suggest that the Amiga is the most popular selling home computer. As well as being affordable, it is very powerful and adaptable with the excellent graphic and sound capabilities. With Mac emulation now possible, its flexibility is widened. No, I don't have shares in Commodore but I am a satisfied Amiga owner. How about looking a little further than the PC and have some articles on (and projects for) the Amiga and other home computers? M. Riley Wynyard, Tasmania Worship not ye the IBM PC or its clones Gaagh! (this is a phonetic transliteration of a strangled scream). I just love reading Ms Bonnitcha's flowing prose, don't you? She babbles on blithely about "personal computers" being only 10 years old in 1991 and seems to feel that IBM was the proud father of them all. Tsk, tsk, what a shameful lack of background knowledge! I (unlike Ms Bonnitcha) don't pretend to be an expert, so please excuse any slippage in accuracy where minutiae are concerned, but I stand by the broader scope of this short note. In fact, there have been "personal'' computers around for much longer than a mere decade. Even so, let us ignore such obvious traps as mechanical calculating devices like the abacus and the Facit adding machine (remember the slide rule?). We will restrict ourselves to the more familiar "boob-tube and keyboard" style that we all know and love, and accept that it is obvious that IBM were quite late on the scene. Their first attempt was nearly laughed into oblivion, in fact. The in- dustry took one look at this completely non-standard, user unfriendly card-frame and reacted with a mixture of mirth and horror. I mean, literally everything was an optional extra. Most things still are today, several abortive attempts and restarts later. But enough of that, let's take a look at the first computers mass-marketed for personal use. They were, in order of appearance, the Apple, Commodore PET (Personal Electronic Transactor, would you believe?) and the Tandy TRS-80. The Apple machine was probably the most serious attempt at a personal computer in those pre-16 bit days. Purposely designed to resemble an electric typewriter in profile, and with a neutral colour scheme, it was supposed to sneak in the back door and take over the whole place. For a while it did. Then the PET appeared. Lower priced, and aimed at the "Captain Comet" fraternity, it invaded (sorry about that) bedrooms, dens and lounge rooms around the world, only to be squeezed out in turn by the TRS-80. The TRS-80 first hit the shores of Australia about 15 years ago. It wasn't much of a machine by today's standards - 4K of DRAM, a deadslow 8-bit Z-80 CPU, a clipped Microsoft BASIC interpreter, and "chunky graphics" . You'd better believe it, in quick-smart time those machines sprouted expansion cases, RS-232 ports, memory, disc drives, printers, the lot. Don't even ask about prices - 16K of memory (only 8 bits wide, remember) cost about a month's salary. A disc drive (5¼ inches single-sided, single density, 40 track) cost about 2½ months' salary. Get the picture? Anyway, despite the fad that there was no way to talk between the three marques, and despite the fact that the machines were unfriendly, to say the least, the software bases for the "Trash-80" and the Apple (and their clones) took off like mad choko vines. There were programs for every kind of application you could think of, from astrology to pig raising to Zen. SILICON CHIP, . PO Box 139, Collaroy Beach 2097. Programmers (usually about 14 to 18 years of age) worked miracles daily in compact, elegant BASIC, Forth, Pascal and machine code. Not knowing that they couldn't do a particular thing, they went ahead and did it anyway. They still exist, out there. You don't see them in a sterile office environment, and they usually steer clear of "suits" and other straights. Being of generally unsound minds (and generally unsavoury habits), they tend rather to be found near pizza shops, and other fast food outlets. Now that there are a couple of generations of these characters, they number in the tens of millions. They have several other characteristics in common - they don't usually buy IBM computers; they buy clones or Atari ST's or Amiga 500's and 2000's and the like, they are still pirates, techno-buffs and hackers, and they still spend money like drunken sailors. Ms Bonnitcha may not know what I've been raving on about (or maybe that's a very old photograph next to her banner) but the Kindly Old Editor surely must. Despite IBM's billion dollar advertising and "product identification" campaigns, there are still readers to whom "IBM" is not synonymous with "Small Personal Computer". Let's have a little restraint when discussing that particular make of computer then, and a little wider view of the market, hmmm? After all, there are something close to 2 million Amigas alone out there (after less than four years of marketing). Whaddya say, Hm? Huh? Kindly Old Editor, can you chivvy the Harrassed Writer into writing about other than flamin' IBM computers? There are, no doubt, other readers out there who also realise that you are the magazine for computer projects and technical articles written for the domestic market. Let's face it, those other two publications are only really interested in more variations on the stereo amplifier theme, and IBM kluges, right? Euan Miller Kyeemagh, NSW MAY1990 3 A new error correction technique for digital recording All digital recording and playback techniques have some form of error correction which allows signals to he restored after transmission errors. But really large errors present a problem in that they can practically destroy the signal. Now, a new technique has been devised with offers significant improvements. At the Philips Research Laboratories in Eindhoven, Raymond Veldhuis has developed a method which allows even large errors in signals, such as speech, music or images, to be restored. For this he makes use of the regularity present in almost every signal. By analysing the error's environment, it is possible to correct the error in such a way that there is no longer any perceptible distortion or picture disturbance. Us1ng knowledge of human hearing, Veldhuis also succeeded in reducing the bandwidth required for the transmission of audio signals by a factor of between six and eight without any audible loss of sound quality. This means that the bandwidth of an FM transmitter can be quite sufficient for the transmission of digital music. The coding method for this bandwidth reduction has been included as a proposal in the Eureka project on Digital Audio Broadcasting (DAB). Digitisation Audio and video signals as we perceive them are analog. Audio signals vary continuously over time; picture signals change continuously as a function of place and time. The continuously changing value of, for example, sound pressure, pitch or picture brightness can be recorded (digitally) with a high level of accuracy by taking a sample of the signal at very specific time intervals. For example, in the case of signals recorded on compact disc, the signal is sampled 44,100 times per second. The sampling frequency is then specified as 44. lkHz. The digitised signal is a series of binary numbers; ie, zeros and ones which are also called bits. If there is a fault, then a bit error can arise with the result that a binary number is no longer completely correct. When the fault is not too large, such errors can be both detected and corrected by adding extra bits to the signal. However, in the case of large errors, such as the loss of several milliseconds of a conversation on a earphone due to interfering reflections from mountains or high buildings, other ways of restoring the digitised signal must be sought. The environment Veldhuis bases his restoration method on the fact that speech, music or picture signals all have a certain regularity, characterised by the signal spectrum. This regularity can be measured and then it is possible to replace the missing numbers in the series so that the restored part of the signal shows, as far as possible, the same regularity as the rest of the signal. Speech signals ........ .... , ~~~········ •••••• ~~L ·•• If the data stream for a picture is corrupted, lots of picture elements will be lost, as shown in this extreme case. 4 SILICON CHIP When applied to speech signals, the technique has been used to restore gaps as long as 12.5 milliseconds. When the restored signals were observed on an oscillograph, the differences between them and the original signals were negligible. And in listening tests, no difference could be heard between the original and the restored signal. The speech sampling frequency in the case of digital telephony, as used in car telephones, is 8kHz ... This photo shows how the new error correction method can restore the seriously corrupted picture on the opposite page. It can also restore badly corr.ected data streams for audio signals. (8000 samples per second). Hence, around 100 consecutive samples were restored in the 12.5 millisecond section of signal. Music signals In the restoration of music signals, Veldhuis also used, in addition to the regularity concept, the fact that a music signal can be considered a s the output signal of a filter. The spectrum is then fully characterised by the filter coefficients. It is thus possible to devise a mathematical equation with which every unknown sample can be estimated on the basis of the preceding samples. If some of the samples following the unknown sample are also known, then a prediction can be made which comes very close to the original sample. In practice, it is possible, at a sampling frequency of 44. lkHz, to fill in up to 30 successive missing samples by calculation, without any musical defeqts being apparent. Picture signal correction Picture signals can also be digitised. Still pictures can be conceived as a changing brightness signal varying according to the position (ie, in two dimensions). With digitisation, the signal be- comes a field of numbers. In such a field, every number represents the brightness of a picture element [pixel). Moving pictures can then be considered as a succession of still pictures. In the (future) transmission of digitised pictures, for example, groups of 8 x 8 pixels will be transmitted. If there is a transmission error then an entire 8 x 8 area can suddenly disappear and this is seen as a picture fault. Restoration can again take place in the manner indicated; determine the regularity in the brightness distribution in the area's surroundings and from this, calculate the brightness of the missing picture elements. As the accompanying photos demonstrate, a picture full of transmission errors can be fully restored - a dramatic demonstration of the technique. Economical coding The digitisation of signals, whether they be music, speech or picture signals, gives an excellent quality of reproduction and, as indicated above, possibilities for effectively repairing damaged signals. There is, however, a price to pay; the sampling frequency required for good quality must be at least twice as high as the highest frequency to be reproduced. In addition, a number of bits are needed to record the content of a sample digitally. An audio signal with a maximum frequency of Z0kHz calls for a sampling frequency of 44. lkHz. Further, to digitally code each sample, an accuracy of 16 bits is required in order to prevent the disturbing influence of rounding errors. In this way, the reproduction of a signal with a bandwidth of Z0kHz requires a bit frequency of 700,000 bits/second; for a stereo signal this figure has to be doubled again. The resulting requirement of 1.4 million bits per second far exceeds the capacity of an FM channel, making economies necessary in the coding of the signals. However, with data compression, the bandwidth required for the transport of digital signals can be greatly reduced. Signal masking Studies of hearing have shown that strong signals with a certain frequency mask weaker signals with neighbouring frequencies; ie, make them inaudible. This only happens if these neighbouring frequencies do not differ too greatly from the frequency of the stronger signal, and their strength does not exceed a certain threshold value (the masking threshold). However, if a musical signal is divided into narrow frequency bands, then it is possible to make do with a rougher coding (less bits per sample) as the resulting interference then remains below the masking threshold. In cooperation with the IRT, the German Institute for Broadcast Technology, and the CCETT, the laboratory of the French Post and Telecommunications organisation, this coding method has now been incorporated as a proposal in EUREKA project 147, Digital Audio Broadcasting. The purpose of this EUREKA project is to arrive at a new transmission standard for digital audio. Footnote: the results described here relate exclusively to laboratory research. They do not involve the marketing or manufacturing of new products. ~ MAY1990 5 hat·s I this year is OUT Store Locations PHONES SECURITY AUDIO COMPUTERS • NSW • Albury 21 8399 • Bankstown Square 707 4888 • Blacktown 671 7722 • Brookvale 905 0441 • Bondi 387 1444 • Campbelltown 27 2199 • Chatswood Chase 411 1955 • Chullora 642 8922 • Gore Hill 439 5311 • Gosford 25 0235 • Hornsby 477 6633 • Hurstville 580 8622 • Kotara 56 2092 • Liverpool 600 9888 • Maitland 33 7866 • Miranda 525 2722 • Newcastle 61 1896 • North Ryde 878 3855 • Parramatta 689 2188 • Penrith 32 3400 • Railway Square 211 3777 • Sydney City 267 9111 • Tamworth 66 1711 • Wollongong 28 3800 •ACT• Fyshwick 80 4944 •VIC• Ballarat 31 5433 • Belmont 43 8522 • Bendigo 43 0388 • Box Hill 890 0699 • Coburg 383 4455 • Dandenong 794 9377 • East Brighton 592 2366 • Essendon 379 7444 • Footscray 689 2055 • Frankston 783 9144 • Geelong 232 711 • Melbourne City 399 Elizabeth St 326 6088 and 246 Bourke St 639 0396 • Richmond 428 1614 • Ringwood 879 5338 • Springvale 547 0522 •OLD• Brisbane City 229 9377 • Buranda 391 6233 • Cairns 311 515 • Chermside 359 6255 • Redbank 288 5599 • Rockhampton 27 9644 • Southport 32 9033 • Toowoomba 38 4300 • Townsvil le 72 5722 • Underwood 341 0844 • SA • Adelaide City 223 4122 • Beverley 347 1900 • Elizabeth 255 6099 • Enfield 260 6088 • St. Marys 277 8977 • WA • Cannington 451 8666 • Fremantle 335 9733 • Perth City 481 3261 • Midland 250 1460 • North bridge 328 6944 • TAS • Hobart 31 0800 •NT• Stuart Park 81 1977 ORDER BY PHONE OUTSIDE SYDNEY (008) 226610 Free Call Sydney Area 888 2105 17& pages in Full Colour VINTAGE RADIO By JOHN HILL Cleaning up the chassis In a number of previous columns I have briefly mentioned how to tidy up the chassis of an old valve radio in order to make it look more presentable. This month, we will take a much closer look at chassis restoration, as the end result has a significant bearing on the overall appearance. Have you ever noticed how meticulous vintage car enthusiasts are with their vehicles? They fuss and polish and dust and clean and their cars always look immaculate. Even under the bonnet the same care is lavished and it is unlikely that any dust or grime will be found on the engine (normally a fairly messy part in most motor vehicles). Likewise with vintage radios. While the chassis is normally a dust encrusted blob inside the cabinet, it is the engine so to speak, and any serious collector will want it to look a part of the restoration and not something that has been forgotten. The chassis can be made to look every bit as attractive as the cabinet and some look so impressive when properly restored that the set should be displayed so that the back view can be seen. In other words, the cabinet often hides the most interesting part. Cleaning up a chassis is not A badly rusted chassis requires anti-rust treatment before repainting. Failure to prepare the chassis properly prior to painting will result in the rust quickly breaking through the new paintwork. 8 SILICON CHIP always an easy task. Because most chassis and electrostatic shields are made of steel, rust is usually one of the main problems to overcome. Even aluminium components can corrode and these sometimes look just as unattractive as rusty steel. Some of my earlier restorations are starting to reveal that a chassis cleanup requires more than just a coat of "Silvafrost". A one-coat touch up with this paint may not last 12 months before the rust starts to break through the thin layer of paint. This comment mainly applies to chassis tops that were severely rust pitted. There are many reasons for a chassis being attacked in this manner. Unloved valve radios are frequently stored in garages and sheds where they are subject to damp, dust and general neglect. Mice often inhabit these old sets and the little puddles they leave behind are highly corrosive. Receivers that have lived their lives close to the sea also have rust problems and some of these sets have to be seen to be believed. Regardless of the reason, a 50-year old chassis can be in a rather sad state and rust often penetrates deep into the surface of the metal. I know of vintage radio enthusiasts who have completely dismantled a radio until they have been left with the bare chassis. This was then suitably treated (even zinc plated in one instance) and the set then rebuilt. While that is a very thorough way of doing a restoration, there are not many of us who are likely to go to those extremes. I know I'm not usually prepared to do that. A fully restored 1936 dual-wave Radiola. This particular chassis clean up only involved repainting the coil cans and other top accessories. The chassis itself was cleaned up with an automotive "cut and polish" compound. The next best alternative is the paint brush. The brush treatment is quite appropriate in many cases because the chassis was originally painted. A coat of a similar colour will brighten things up nicely. However, in some instances a touch up is not adequate if one wants the job to last and chassis restoration often requires a bit more effort than five minutes with a paint brush. Preparing a radio chassis for painting is no different to any other painting job. The rust must be removed and the corroded area treated with a rust inhibiting paint such as "Kill Rust". Kill Rust metal primer under a couple of coats of Silvafrost or enamel paint must help to contain the rust. Hopefully, such a treatment would be permanent and no further rust problems should arise. If the chassis is to be treated properly then one must have access to it. This means that it needs to be stripped of all the removable components that are likely to get in the way. Valves and valve shields are easily removed so these items hardly warrant a mention, although I believe that is about as far as some The advantage of a good clean and polish is that all the original inscriptions, transfers, etc are retained. However, not many chassis are as well preserved as this one after half a century. restorers are prepared to go. In recent months, I have restored two chassis and these have come up really well. Perhaps the main reason for them looking so neat is the fact that they were stripped of a good deal more than the valves and valve shields. With these particular chassis, all the coil cans, the dial mechanisms and the tuning capacitors were removed before the paint preparation work commenced. How much easier it is to paint coil cans when they are no longer part of the chassis. How easy it is to clean and paint a chassis, particularly around the edges of coil cans and under the tuning capacitor. How easy it is to clean and paint a tuning capacitor when it can be done on the workbench. The tuning capacitor on the 6-valve Eclipse radio chassis (as shown in one of the accompanying photographs) proved to be interesting and warrants further discussion. Tuning capacitor tweaks While cleaning the tuning capacitor, I was alarmed to see that some of the moveable plates were badly positioned. Some were almost touching, while others had quite large gaps. This prompted me to check out the capacitance with my digital multimeter. My suspicions were justified and in some positions there was approximately 8pF difference between the three gangs. Although this power transformer was left bolted to the chassis, it was painted with the nuts removed and the laminations highlighted in black to improve its appearance. MAY 1990 9 This 6-valve chassis was manufactured by Eclipse Radio and would be about a 1934 model. Its colour scheme is gold, silver and polished aluminium. It really is too good to put back into its cabinet. I sought to remedy the situation and spent about three quarters of an hour re-adjusting the capacitor plates. The improvement was considerable to say the least and the final result was a tuner that had no worse than lpF variation at any setting. Such an adjustment could have a significant effect on the overall performance of the receiver. In future, more tuning capacitors will be removed from their chassis and it will not be for ease of cleaning and painting alone. Another advantage of a more thorough chassis job was revealed when the coil cans, etc were removed from a 5-valve Radiola. With this receiver, the sealing wax that moisture-proofs the coils and the IF transformers had dried and cracked with age, leaving numerous gaps of several millimetres in width. Removing the cans not only reveals such problems but also allows an inspection to be made of the fine wiring which is normally out of sight while the coil cans are in place. Removing 54 years of dust accumulation and melting some fresh The tuning gang of the Eclipse was removed to make it easier to paint and to provide easier access to the chassis. It also made it possible to re-align the three sections of the gang using a digital capacitance meter. 10 SILICON CHIP wax sealant into the cracked moisture proofing must also help to produce a more reliable restoration. Not all chassis need repainting and the 5-valve Radiola is still original as far as its main chassis is concerned. However, the power transformer and coil cans have been repainted because these components were beginning to look tatty. The advantage of not painting the main chassis is that all the manufacturer's stencilled inscriptions remain intact; eg, aerial and earth terminals, valve types etc. It is always advisable when not painting the chassis to clean it thoroughly with hot soapy water and a cloth, being careful not to slosh water everywhere. When dry, a rub over with automotive polish will bring back the shine to the old paint surface. It will also quickly remove various marks and stains that the hot soapy water treatment failed to dislodge. Car polish The car polish technique really rejuvenates the old paint work and helps to tidy up the general appearance of the chassis. The cut and polish treatment also works on a plated chassis that has become dull and powdery but not yet gone rusty. The polish will bring up the surface to a reasonable lustre. It also leaves a protective coating to help prevent further corrosion. Removing the electrostatic shields allows the coils and IF transformers to be inspected and cleaned. They look better with the cans on, don't they? ACTIVE SHORT WAVE ANTENNA TECHNIKIT AT4SW (SEE SC JAN '90) ,i_ ii_·. ;tl COMPLETE KIT $59 BUILT and TESTED $119 (BATTERIES INC) CASE $10 LOOP ANTENNA ..... ~ This HMV radiogram used a plated chassis. An automotive cut and polish compound cleans metal components quite well and leaves a protective coating. The two finishing techniques for chassis were either paint or plating. Generally speaking, painted chassis were common in pre-war radios while the plated steel type was more common after the war. The plating was usually cadmium but plated chassis appear to be more rust-prone than those that were painted. Perhaps it depends on how the sets have been stored over the years. In the very early 1930s, aluminium chassis were popular but were in vogue for only a short time. Aluminium is a relatively weak metal and chassis made from this material were not very rigid. Aluminium also caused difficulties because it cannot be readily soldered to. However, it did not require painting or plating for protection from atmospheric corrosion. One problem with the old Radiola chassis was that it had been modified. The aerial coil had failed (possibly due to corrosion) at some time in the past and it had been replaced with a smaller more modern coil. This coil had been installed underneath the chassis whereas the original one was on top. Unfortunately the repair left tw:o odd shaped holes showing where the original coil and can had fitted. There was no problem with the effectiveness of the repair, it was just that the gaping holes looked a bit rough and that there was obviously Q TECHNIKIT PX1 COMPLETE KIT $44 BUILT and TESTED $69 (SEE SC JUNE 89) Improved signal strength & signal quality in a portable tunable antenna. PACKING & POSTAGE IN AUSTRALIA INCLUDED IN PRICES QUOTED. WRITE OR RING FOR BROCHURES ORDERS ACCEPTED ANYTIME PAYMENTS BY BANKCARD, VISA, MASTERCARD, CHEQUE or MONEYORDER TRADE ENQUIRIES WELCOME JILOA PTY LTD (TECHNIKIT DIVISION) P.O. BOX 73, GLENHUNTLY, VIC 3163 Phone (03) 571 6303 VALII UN1L NOV. 1990 Resurreetion This coverplate looks better than the two odd shaped holes that someone had hacked into the chassis. It also excludes dust and mice. something missing. The problem was simply overcome by fitting a cover plate over the unsightly area. The plate was painted the same colour as the other mounted components and doesn't look that much out of place. It keeps out dust, mice and other vermin and hides untidy parts of the chassis from view. All things considered, the chassis and how it looks are an important aspect of vintage radio restoration. Making this part of a radio look new again is often quite a challenge but when completed gives a great deal of satisfaction. Although the treatment described in this article takes a good deal more time than a quick one coat touch up, it all seems worthwhile when the job is finished. ~ Radio The original vintage wireless specialists Our skilled technicians offer QUALITY repairs & restoration . We have a large stock of bakelite and timber radios fully restored and for sale. Valves, high voltage capacitors and other specialised parts available. ADDITIONAL SERVICES COPIES OF: CIRCUIT DIAGRAMS $5.00 SERVICE MANUALS $10.00 AVAILABLE FOR MOST MAJOR AUST. MAKES FROM 1934 ONWARD. WANTl:D - valves, radios, etc., purchased for cash. Call in to our showroom at: 51 Chapel Street, Windsor, Vic 3181 PO Box 1116 Telephone: (03) 529 5639 MAY1990 11 l ~ SHdt4,:i BOARD SOLUTIONS Pty Ltd j ,____ _ _ M_o _TH _E _R _e_o_A_R_o_s_ ___.l I 10MHz XT, 640K RAM M1010 99.00 10MHz XT, 1MB RAM M1000 129.00 33MHz XT286 M1020 199.00 Baby 286, 20MHz/0K RAM M2000 695.00 286, all-in-one, OK RAM M201 O 545.00 Baby 286, 12MHz OK RAM M2020 499.00 Half-size 286, 1MB RAM M2030 449.00 12MHz NEAT 286 OK RAM M2040 599.00 20MHz 286 OK RAM M2045 845.00 16MHz 386SX, OK RAM M3000 995.00 25MHz 386, 32K Cache, OK M3010 2495.00 33MHz 386, 32K Cache, OK M3020 2795.00 .------------------, YE-Data 360K YE-Data, 720K/1.44M 03000 drive Plus Frame YE-Data, 1.2MB CHIPS 1M RAM Chip • 1OOnS 1M RAM Chip - sons 256K RAM Chip - 1OOnS 256K RAM Chip · sons 8087-2, 8MHz Co-Processor 4 X 256K RAM Chip, 1OOnS 4 X 64K RAM Chip, 120nS For VGA card 64K RAM Chip - 120nS NEC V20 Chip NEC V20 Chip, 10MHz NEC V30 Chip, 10MHz 64K RAM Chip - 1OOnS 80387SX 16MHz Co-Processor 64K 1OOns RAM Chip 2C87-8MHz (equiv 80287/8) 2C87-10MHz (equiv 80287/10) 2C87 -12MHz (equiv 80287/12) 2C87-20MHz (equiv 80287/20) 3C87-16MHz (equiv 80387/16) 3C87-20MHz (equiv 80387/20) 3C87-25MHz (equiv 80387/25) 3C87-33MHz (equiv 80387/33) SIMM Module, 1MB 80ns Z9300 Z9380 Z9400 Z9480 Z9500 Z9200 29.95 32.95 8.95 9.75 275.00 32.95 Z9212 Z9112 Z9000 Z9010 Z9020 Z9210 Z9540 Z9210 Z9550 Z9555 Z9560 Z9565 Z9570 Z9575 Z9580 Z9585 Z9680 12.00 4.95 24.95 39.95 49.95 5.45 995.00 5.45 449.00 495.00 549.00 649.00 649.00 749.00 949.00 1099.00 295.00 INTERNAL FLOPPY DISK DRIVES 05500 03000 0301 O 0551 o 11 145.00 175.00 199.00 175.00 INTERNAL HARD DISK DRIVES I NEC 42 MB, 2BmS 3 _5in DBOOO plus Frame NEC 42MB 22ms AT BUS 3.5in NEC 3 _5in 134MB 23 mS ESDI DBOOO 0801 O 08020 08030 745 _00 775 _00 795 00 1595:oo NEC 3.5in 134MB 23 mS SCSI NEC 5.25in 179MB 18mS ESDI NEC 5.25in 380MB 18mS ESDI NEC 5.25in 760MB 16mS ESDI NEC 5.25in 380MB 18mS SCSI NEC 5.25in 760MB 16mS SCSI Kalok 20MB 40mS Seagate 20MB ?Oms RLL inc XT controller. Seagate 20MB 65ms RLL inc XT controller Seagate 30MB 65ms MFM inc XT controller Seagate 40MB ?Oms MFM inc XT controller Seagate 5.25in 40MB 40ms RLL Seagate 5.25in 40MB 28ms RLL Seagate 5.25in 65MB 40ms RLL Seagate 5.25in 65MB 28ms RLL Seagate 20MB 5.25in40ms MFM Seagate 20MB 5.25in28ms MFM Seagate 30MB 5.25in40ms MFM Seagate 30MB 5.25in28ms MFM Seagate 30MB 3.5in 40ms RLL Seagate 30MB 3.5in28ms RLL Seagate 49MB 3.5in40ms RLL Seagate 49MB 28ms RLL Seagate 42MB 24ms V/C DB0 4 0 08050 08060 08070 08080 08090 08095 1795 -00 1995.00 3995.00 5995.00 4195.00 6195.00 399.00 08200 499.00 08210 529.00 08220 579.00 08230 08240 08250 08260 08270 08300 08310 D8320 D8330 D8350 08360 08370 08380 08390 625.00 649.00 699.00 739.00 799.00 429.00 479.00 599.00 649.00 549.00 599.00 649.00 699.00 749.00 EXTERNAL FLOPPY DISK DRIVES For Amiga 500, 1000, 2000, 3.5in 880K For Amiga 500, 1000, 2000, 5.25in 360/880K For Commodore PC1, 5.25in 360/720K 40/80 track For Atari ST series, 3.5in 720K For Atari ST series, 5.25in 360/720K 40/80 track For Amstrad PC1512/1640, 3.5in 720K For IBM XT, 3.5in 720K XT For IBM AT, 3.5in 1.44MB For IBM XT, 5.25in 360K For IBM AT, 5.25in 1.2MB For TOSHIBA laptop series, 5.25in 360K For TOSHIBA laptop series, 5.25in 1.2MB D9500 249.00 09510 299.00 09520 09530 299.00 299.00 09540 299.00 09550 09560 09570 09580 09590 269.00 299.00 329.00 299.00 329.00 09600 349.00 09610 399.00 MICE & JOYSTICKS Joystick Logitech Mouse, 2 button serial Logitech Mouse, 2 button serial + Paint SiW Logitech Bus Mouse, 2 button +PaintSiW Mouse Mat J1000 J101 O 49.95 149.95 J1020 149.95 J1030 J1040 149.95 7.50 MONITORS Monitor, 14in TTL, Amber Monitor, 14in TTL, Green Monitor, 14in TTL, Paper White Monitor, 14in EGA Monitor, 14in VGA Monitor, 14in Multisync Monitor, NEC 14in Multisync 30 M4000 M4010 M4020 M4030 M4040 M4050 M4060 249.00 249.00 249.00 599.00 749.00 899.00 1275.00 PHONE OR FAX NOW FOR LATEST PRODUCTS PRICES AND INFORMATION BOARD SOLUTIONS KIT COMPUTER: ASSEMBLE IT YOURSELF AND $AVE! Hurry! While stocks last make big savings on our easy-to-assemble kit computers -with our exclusive return coupons which guarantee success. Normal great value: this month, amazing! Two models to choose from at these ridiculous prices: XT360 - 4.77110MHz speed, 640K memory and 2x 360K floppies. Serial , Parallel and Games ports included, your choice of three graphics modes. While stocks last .. . Mono EGA VGA Normal Now Normal Now Normal Now $1495 $995 $2050 $1595 $2350 $1795 ATH32: 8112MHz speed, 1MB memory and 32MB hard disk drive, 2 serial, 1 parallel and games port, Look at these savings! Mono EGA VGA Normal Now Normal Now Normal Now $2395 $2095 $2950 $2695 $3250 $2895 I SAVINGS at Board Solutions. Computers - this month only! II MICRO CHANNEL Dual Sync Adaptor , PS/2 2MB RAM Card, PS/2 OK RAM 8MB RAM Card, PS/2 OK RAM MC1000 349.00 MC1010 349.00 MC1020 599.00 11080 2 Ser. 1 Parallel AT board 1 Ser. 2 Parallel XT/AT board 11100 11090 Chip Set ( 16450) 11041 Chip Set & Cable suit 11040 11000 Multi 1/0 Card XT only Multi 1/0 Card, 2 Ports all 4 drive 11010 types supported 11020 Parallel Printer Card 11030 Serial PortCard X 1 11040 Serial PortCard X 2 11050 1/0 Plus Card - XT Only 11060 Serial/Parallel Card - XT/AT 11070 2 Serial, 2 Parallel, AT Games, Parallel Printer, Serial Card, 11080 'XT'& 'AT' Multi-Serial Card, 4P-AT 11090 84 Key Keyboard XT/AT101 Key Keyboard , XT/AT 101 Key Keyboard+ TrackBall II 1/0 CARDS 149.00 29.95 55.00 79 .00 99.00 55 .00 75.00 I 349.00 449.00 129.00 249.00 V1040 99.00 Adelaide Albany Broken Hill Cannonvale Charlestown Coifs Harbour Devenport Glen Innes Hobart lnverell Ipswich Leeton Lightning Ridge Lismore Mackay Maryborough Melbourne Morwell Mount Gambier Mt Isa Mudgee Nambour Narrabri Taree Townsville Wagga wagga Warnambool Windsor 55.00 130.00 99.00 349.00 399.00 225.00 249.00 249.00 275.00 249.00 275.00 125.00 145.00 C1000 Hinged , Baby AT C1005 Full Size Hinged AT Case C1010 Hinged Baby AT w/200W PSU C1020 Slimline 'XT' or 'AT' with PSU C1030 3.5in Hard Disk Ext. + Cable 5.25in Floppy Disk Ext. + Cable C1040 C1050 5.25in Full Height Ext. + Cable C1060 5.25in Mount for 3.5in Drive C1070 Baby Tower Case AT Baby Tower Case+ 200W PSU C1080 Tower for 6 Dev. , Swit. at Top C1090 Tower for 6 Devices, + 200W PSU C1110 Switches at top 125.00 175.00 249.00 275.00 99.00 115.00 125.00 25.00 160.00 299.00 299.00 175.00 P2030 P1500 P1510 P2000 P2010 P2200 P2300 P9000 149.00 85.00 124.00 149.00 149.00 195.00 695.00 3.95 2 2 799 412 077 884 908 466 898 439 600 525 684 248 322 323 661 348 232 223 769 281 6155 532 081 290 579 214 137 511 723 214 559 670 6474 346 133 250 400 433 475 723 895 411 604 923 274 526 603 724 466 216 558 629 870 775 935 • 14 Day money-back guarantee (except software) • At least month 3 warranty on all our products: Many have 12 months warranty. • Mail orders are our speciality! • Freight on normal size items is $9.00 • Insurance $1.00 per $100 of order value • All price INCLUDE sales tax • We accept Visa, Bankcard, Mastercard and Post Office COD • Call for our latest price list • Special prices apply until May 31, 1990 _ or while stocks last! Tl{~~{{{{t~~{;'~~,g~~!~';~!~~~~~~~f:..aR""----1 • available: Leasing facilities just ask! ~ .:.::.:;::.:,,~i. ,. 99.00 265.00 245.00 295.00 299.00 349.00 CASES P2020 Microtrorncs Micro Electronics Hobbies And Electronics Whitsunday Decor Newtronics Coifs Harbour Electronics Al Electronics John Sommerlad Electronics Beta Electronics lnverell Computer Bits ACR Computers Leeton Audiotronics Cycle & Sound Decro Electronics Steven's Electronics Keller Electronics Electron ic Component Shop Morwell Electronics Hutchesson's Communic. Outback Electronics Headware Nambour Electronics Namoi Computers Brad's Electronics Super Solex Ph1llip's Electronics Maartronics Windsor Communications R1000 R1010 R1020 R1030 R1040 R1050 Tower for 6 Devices, Switches in Middle Tower for 6 Devices,+ 200W PSU , Switches in middle Case, hinged XT II E1000 E1030 E1010 E1040 E1050 E1060 E1070 -E1080 E1090 E1100 E1105 E1110 E1120 Floppy Disk Card, 4 Ports 360K Disk Cont 4 port, 2In 2Ex or 4In Floppy Disk Card All Drives ESDI Hard Disk Cont Card - AT ESDI HDD/FDD Card - AT Hard Disk Cont, 1:1 lnt. AT HDD/FD D Cont, 1:1 lnt. AT Hard Disk Cont,1 :1 lnt. RLL , AT HDD/FDD Cont, 1:1 int, RLL , AT SCSI Card for AT SCSI HDD/FDD for AT Hard Disk Controller, XT Hard Disk Controller, RLL-XT POWER SUPPLIES 200 Watt PSU Suit Tower Case 200 Watt PSU Suit Baby Tower Case 150W PSU , Circuit Board 150W Switching PSU - XT 200W Switch PSU - Baby AT 200W PSU, Baby AT, L Type 220W Switching PSU -AT 200W PSU With Battery Backup 150W PSU Cap . 220nF/200V 95.00 115.00 199.00 DISK CONTROLLER CARDS 99.00 245.00 V1000 V1010 V1020 V1030 K1000 K1010 K1020 RAM CARDS RAM Card, OK RAM, XT only 2MB RAM Cd , OK LIM/EEMS AT 2MB RAM Cd , OK LIM/EEMS XT 6MB RAM Card, -OK RAM 4MB Fast Card Suit 20MHz +SX 32 Bit RAM Card 25 + 33MHz 99.00 65.00 34.95 29.95 129.00 VIDEO CARDS VGA Card, 800 x 600 VGA Card, 1024 x 768 Magic Combo CGA Card EGA Card, with Hercules Mode Mono Hercules Card , 16MHz operation + Parallel Port KEYBOARDS C1120 299.00 C1130 C1140 499.00 95.00 INTERFACE CARDS 48 Line 1/0 Card F1000 Serial RS-422 Adaptor F1010 Industrial 1/0 Card F1020 Universal Wire-wrap Card F1030 Dual Serial RS-422 Card F1040 80286 Speed-up Card F1050 IEEE 488 Interface Card F1060 IEEE 488 Interface Card- National Compatible F1070 A-DID-A Converter, 12 bit, 1 Ch. F1080 A-D/D-A Converter, 12 bit, 2 Ch. F1090 Clock Card - XT F1100 EPROM Writer Card F1110 Games Card- 'XT'& 'AT' F1120 I 110.00 135.00 445.00 125.00 195.00 495.00 299.00 549.00 199.00 449 .00 50 .00 245.00 35.00 NETWORK BK Ethernet 8 bit with T Adaptor 16K Ethernet 16 bit with T Adaptor Ethernet 50 Ohm Terminator Thin Ethernet Cable , 25 feet Thin Ethernet Cable, 50 feet Thin Ethernet Cable, 75 feet Auto Boot ROM for NEE1 Auto Boot ROM for NEE2 Workstation , 12MHz Diskless, with 1MB RAM N1000 399.00 N1010 N1020 N1030 N1040 N1050 N1060 N1070 449.00 12.75 35.00 49.00 62.00 35.00 35.00 N2000 2495.00 CABLES OH NOi We 've run out of room to show you our great range of cables , connectors and Gender . Benders. For details of any of these products, give Board Solutions a call today - no obligation, of coursei 499.00 BOARD SOLUTIONS IS YOUR ONE-STOP PC ENHANCEMENT COMPANY ~SHUd,~ BOARD SOLUTIONS Pty Ltd PO BOX 1120, LANE COVE NSW 2066 TEL (02) 906 5696 FAX (02) 906 5222 Interesting circuit ideas which we have checked but not built and tested. Contributions from readers are welcome and will be paid for at standard rates. OFF Delay circuit for intermittent wipers This circuit was designed because my 1980 Mitsubishi Mirage (Colt 'in Australia) didn't have an intermittent wiper delay circuit and we in Dunedin often get intermittent light rain (not a problem for Sydney-siders who now have to carry a spare lifeboat). The circuit is based on a 555 timer IC wired for astable operation. Sla switches power to the circuit while S1 b selects one of four timing resistors (22k0, 33k0, 56k0 or 100k0). These provide timing delays of 4 seconds, 5s, 7.5s and 12s respectively. The tokO resistor between pins 6 & 7 sets the discharge time of the lOOµF timing capacitor to about 0.7s. Pin 3 of !Cl thus switches low for 0.7 seconds at the end of each delay period and turns on PNP transistor Qt. Qt drives relay RLl which in turn provides 0.7s switching pulses 100k I It's quite easy to modify the 12V sealed lead acid battery charger featured on page 11 of the March issue to charge 24V batteries. All you have to do is to change four resistors (RA, RB, Re and RT) and a capacitor, as shown. Note that all resistors must be 1 % types. Using the values shown, the overcharge voltage (Voc) is now 29.2V while the float voltage (VF) becomes 27.2V. Note that the power supply voltage will have to be about 36V to allow for the increase in battery voltage. Make sure that the pass transistor Qt has adequate heatsinking. The circuit shown is capable of 14 SILICON CHIP 220 ;flt 22k J ODFF 01 ' ' 8C557 ICl 16VWr ; ~ . _,.. ~·"' -------OC 1 CONNECTOR BLOCK _:: j i:::::::, .,. 555 ~ .,. '' s,, -F° ..,.0---BL/OR BL/WHT---<::J"' 0-BLK (EARTH) TO CONNECTOR BLOCK MITSUBISHI MIRAGE WIPER SWITCH TO MODIFY CUT 8l/WHT WIRE for the wiper circuit. This should be enough time to move most windscreen wiper motors from their park position. The completed circuit was fitted in a plastic case with all external connections routed via a screwdown connector block. Installation in the Mirage is a little tricky. First, you have to identify the SPDT switch that's used to in- itiate a single wipe. You then have to cut the wire to the switch wiper and wire up the relay contacts as shown in the above diagram. Other cars will require a different installation procedure. For example, in some cars it may be necessary to use the relay to switch + 12V to the wiper motor. Malcolm Young, Dunedin, NZ. ($20) D2 1N5404 24V gel-cell battery charger 10!) + 36V -i D1 1N5404 BATTERY 24V 0.5A 03 1N5404 4701! ... 2 4 16 RA 360k 15 11 .,. 12 RB 33k IC1 UC3906 13 10 RD 560k RC 36k .,. 14 24V GEL-CELL CHARGER charging at up to 500mA but if this is too low, calculate a new value for Rs using the formula: Imax = 0.25V/Rs, If this current is to be more than lA, make Qt a BD650 Darlington transistor. I S2 RESET 01 1N4148 180k 1M D2 1N4148 1M 10 13 IC1b 0.1 0.1 +6V + 11 .,. 10:r 0.1! + PIEZO SOUNDER S3 POWER 220k +6V---O~ T 6V 1 I ~ Adjustable boxing timer Wanna have a go, mate? - at building this adjustable boxing timer that is. It's based on three ICs and features adjustable work & rest periods. The work period is adjustable from 2.75 to 22 minutes, while the rest period can be varied between 27-90 seconds. At switch-on, Q2 is pulsed on by virtue of the 0.15µ,F capacitor and resets IC1 (a dual 556 timer). At the same time, the 0.15uF capacitor briefly pulls pin 4 (reset) of D-type flipflop IC2 high, thus setting Q low and Q-bar high. These two outputs drive separate timing resistor net- works which set the charging period of a 470µ,F capacitor on pins 1 & 2 of ICla. When Q-bar is high, the 4-70µF timing capacitor charges via D3, VR1 and the parallel 330k0 and 1MO resistors. The time taken for the capacitor to charge determines the work period and is set by trimpot VR1. ICla is one half of an LM556 dual timer IC and is wired as a monostable. When the voltage across the timing capacitor reaches 2/3Vcc, pin 5 of ICla switches low and triggers IC1 b. Pin 9 of IC1 b then provides a 2-second pulse which activates the piezo buzzer and turns on Ql. ft1 2-phase oscillator uses a flipflop Ever required an oscillator to finish a prototype circuit but only had a D-type or J-K flipflop left over? This simple circuit solves that problem by using a flipflop circuit to generate a 2-phase signal. The circuit relies on the fact that both the 4027 J-K flipflop and the 4013 D-type flipflop have overriding set and reset inputs, as well as Q and Q-bar outputs. Assume that Q-bar is initially high when power is first applied. Cl thus charges via Rl until, D1 C1J 1N4002 7 v+ 16 s SL Q IC1 4027 LJ 1N40D2 R2 C2! after time period R1C1, the set (S) input is sufficiently high to switch Q high. + At the end of the 2s pulse, Ql turns off and so the clock input (pin 3) of IC2 goes high. This toggles the flipflop so that Q is now high and Qbar is low. The 470µ,F capacitor now charges via VR2 which determines the rest period. At the end of the rest period, the buzzer sounds again, IC2 toggles, and the work period timing cycle re-starts. LED 1 and LED 2 are used as status indicators, to show either the work or rest period. When Q-bar of IC2 is high, Q4 turns on and lights LED 2 (work). Similarly, when Q is high, Q3 turns on and lights LED 1 (rest). Steve Calder, Parramatta, NSW. ($25) When Q switches high, Q-bar switches low and so Cl now discharges via Dl. At the same time, C2 charges via R2 and, after time period R2C2, resets the circuit. This switches Q-bar high and Q low again and so Cl again charges via Rl while C2 discharges via D2. This sequence is repeated indefinitely while ever power is applied. The circuit shows the pin connections for one half of a 4027 dual J-K flipflop. Note that the pin connections are different for a 4013. Darren Yates, French's Forest, NSW. ($20) MAY 1990 15 Fingerscan Personal Identification Are you who you claim to be? Now there is a machine which can verify that you really are who you say you are. It can be used in any application where security is important and is sure to revolutionise many areas of government and banking. By LEO SIMPSON Do you have a password to gain entry to your company's computer? Well, what happens if someone else discovers your password? Unauthorised entry, that's what ! And do you have an ID card for entry into your workplace or company carpark? If someone else gets your card, you are no longer authorised, are you? And of course, if someone purloins your credit card or automatic teller card, you could be in for a big loss if you don't notify the banks quickly. Now there is Fingerscan, a security device which could make all these problems and a lot of others a thing of the past. Fingerscan is an electronic fingerprint scanning machine which records and stores your fingerprint in computer memory. The pictures accompanying this article show two different Fingerscan machines, one used in a building security system, to control access through a main door. The other unit is used in conjunction with a computer system instead of a password system. As you can see, with both units you just put your finger over a plastic window. The unit then scans your finger and shortly after you are either identified or asked to try again. According to the distributors, Lynwood Pacific Pty Ltd, the Fingerscan "is based on digital holography and involves a small reading device about the size of a thumbprint which reads 3-dimensional data from the finger such as skin undulations, ridges and valleys, reflections and other living characteristics". Sounds like a fingerprint, doesn't it? CCD camera The heart of the unit is a CCD (charge coupled device) camera which takes three pictures (or scans) 16 SILICON CHIP The Fingerscan ID system can be used instead of the more traditional password to control access to a computer system. It makes unauthorised access virtually impossible. of the finger . For each separate scan, the finger is lit by a light emitting diode. For the first scan the red LED is lit; for the second, the orange LED and for the third, the green LED comes into play. Each of the LEDs illuminates the finger from a slightly different angle so that the image detail recorded by the CCD camera is not the same. So while the information recorded is 3-dimensional in nature, it is probably not strictly correct to say that the process is holographic. However, the optical system of the CCD camera and the alignment of the LEDs illuminating the target area are critical to the accurate functioning of the device. The analog picture information recorded by the CCD camera is converted to digital data and processed in a module which employs a 68000 microprocessor and a large custom gate array. The processor board processes the data , compresses it and then stores it as a 1.2K byte ASCII file. This data is unique and is called the user's "template". From there on, the Fingerscan system can be as simple or as complex a necessary. The Fingerscan desktop unit can be used to merely control access to a single user or multi-user computer system or it can be part of a very much larger system. Similarly, a larger free-standing Fingerscan unit which has its own numeric keyboard for users to enter in an ID number can simply control entry to a building or it can also be part of a larger system. The latter Fingerscan unit (with numeric keyboard) has the processor stored in a separate box which also accommodates other sensor inputs and relay outputs (to control door striker plates and so on). It can be coupled to a security system via a serial RS-232 or RS-485 cable. The processor for the desktop Fingerscan unit is on a large card which fits into a fullsize slot in any IBM PC/XT/AT or compatible. For Features and Performance ... Wider implications I have tried the Fingerscan unit and it is very simple to use. You just put your finger on it, press down and you are immediately identified. In most installations, there would be no need to carry an identity (ID) card which most people hate doing. And, of course, while it is just as accurate as conventional finger-printing it is far faster, far less embarrassing and there's no messy ink. Ultimately, it is envisaged that each person's data "template" could be stored on a "smart card"; ie, a card with data storage and a processor on it. Then, even if you lost your card, nobody else would be able to use it - they would not have your fingers . In really high security applications, users could be "enrolled" into the system using two or more fingers. If they were under duress they could use their left index finger, or any other finger for that matter. It would be impossible to beat. In the future, it is expected that banks, and the Australian Department of Social Security will become big users of the Fingerscan system. After all, if you have-to use your finger each time you apply for social security, there would be very little chance of defrauding the system. "Double-dipping" would be a thing of the past. For further information on the Fingerscan system, contact Lynwood Pacific Pty Ltd, Unit 12/39 Herbert Street, St Leonards, NSW 2065. Phone (02) 439 5433. Alternatively, contact Bio-Sec International Pty Ltd, 17 Yallourn Street, Fyshwick, ACT 2609. Phone (062) 39 1621. ~ ...:!:.I"" ' :' ... .!... '. Prices include TWO x1/x10 switch probes Convenient XY operation for measuring phase differences between two waveforms Variable sweep control incorporating x10 magnifier Uncal and trigger warning lights TV-V & TV-H triggering Trigger hold-off High sensitivity- 1mV/div Stable low drift design 8 divisions of displayed dynamic range with accurate distortion-free waveform measurement Special TV sync separation circuits for measurement of video signals Delayed sweep function (OS7040A) ±3% accuracy 0S7020A $650 ex tax $733.50 ln11 tu• OS7040A $1045 ex tax $1243.55 /nl/ tax• • Cursors for direct measurement of waveform voltage, time and frequency e 20MHz bandwidth • 1mV max sensitivity • Similar performance to 0S7020A 0S8020R $1045 ex tu $1243.ss 1•11 tu• Supported & Serviced Australia-wide by Elmeasco Instruments Pty Ltd Dealer enquiries welcome. Call (02)736 2243 'Recommended prices only You've Gotta Getta Goldstar from: The free-standing version could be used to control access to a building or a restricted work area, or it could form part of a larger ID sytstem (eg, for social security screening). A.C.T. John Pope Electrical 80 6576 N.S.W. Ames Agency 699 4524 • D.G.E. Systems (049) 691625 • W.F.Dixon (049) 69 5177 • Macelec (042) 291455 • Newtek (042) 271620 • Novacastrian Electronic Supply (049) 62 1358 e Obiat Pty Ltd 698 4776 e Digital 709 6511 e Geoff Wood 4271676 N.TERRITORY J Blackwood (089) 84 4255, 521788 e Thew & Mccann (089) 84 4999 QUEENSLAND St Lucia Electronics 252 7466 e BAS. Audiotronics 844 7566 e The Electronics Shop (075) 32 3632 • Solex (Townsville)(077) 72 4466 • Xanthos Electrical (079) 27 8952 $.AUSTRALIA Elmeasco (08) 344 9000 VICTORIA G.B. Telespares 328 4301 • The Electronic Components Shop 670 6474 • Factory Controls (052) 78 8222 • Mektronics Co 587 3888 • Truscott Electronics 723'3094 W AUSTRALIA Atkins Carlyle 4811233 e Leda Electronics 361 7821 PAPUA NEW GUINEA TE (P,N.G.) Pt Moresby 25 6322 Lae 4Z 6246 ffigh energy ignition for cars with reluctor distributors This high energy ignition system is a variant of the circuits published in the May and June 1988 issues of SILICON CHIP. It is especially intended for reluctor distributors and features improved protection for the coil and main switching transistor. By JOHN CLARKE & LEO SIMPSON Our high energy ignition sytems described in the May and June 1988 issues of SILICON CHIP have been very popular with car enthusiasts all over Australia and many people have written to say how pleased they are with with them. Based on the Motorola MC3334P ignition IC and MJ10012 high voltage Darlington switching transistor, the circuit has been easy to build and very reliable. But while a thousand of more ignition kits have been built by satisfied readers, we have also had a steady stream of requests from DISTRIBUTOR HOUSING MAGNETIC PICKUP ASSEMBLY ADVANCE PLATE SLEEVE ARMATURE FIXED BASE PLATE 18 SILICON CHIP readers who want to use the high energy ignition module with reluctor distributors. There have been two main reaso:n for this. First, some people have had cars like the Mitsubishi Sigma in which the factory fitted ignition module has failed. Rather than pay several hundred dollars for a new ignition module (which does seem outrageous), readers have wanted to substitute the SILICON CHIP high energy module. Second, some readers who own Ford Falcons or Holdens with six or eight cylinder motors have wanted VACUUM ADVANCE PULL ROD to upgrade their car ignition system by using a reluctor distributor from a later model. Where the car has had a distributor made by Lucas there has been a more pressing reason - you can no longer buy Lucas distributors so if your old one is worn out, you are faced with a substantial cost for a new dizzy made by Bosch. So why not go for a reluctor distributor from a later model, from a wrecker's yard? Our response when asked these questions by readers has been to refer them to the data article on the MC3334P ignition IC published in the May 1988 issue of SILICON CHIP. This article accompanied the high energy ignition system in that issue and featured the chip in a Motorola applications circuit with a reluctor distributor (made by Delco; ie, General Motors). In ·an cases we have stated that we had not tried the circuit but readers have often gone ahead nonetheless. In some cases, with Fords and Holdens, they have been successful but in others, notably the Mitsubishi Sigma, the circuit has OVAL VACUUM ADVANCE ASSEMBLY CARBURETOR CONNECTION Fig.1: a reluctor distributor uses a toothed wheel on the distributor shaft and this runs close to a coil/pole piece assembly. As each moving tooth comes close to the coil, it generates a voltage which then triggers the electronic ignition module. This is what the ignition module looks like when all the components have been installed on the printed board and then fitted into the diecast case. The diecast case serves as a heatsink for the switching transistor. Note the loop in one lead of each of the zener diodes. worked only spasmodically and has not been viable. We wanted to know why? To find out, we went the same route as any reader would have. We obtained a reluctor distributor for a Mitsubishi Sigma from a wrecker's yard - the going rate is about $100. We then set up the distributor so that it could be driven by a motor in a bench jig and measured the waveform and voltage output at different speeds. Having assured ourselves that the distributor was producing the typical reluctor output waveform and that it was within the expected limits, we then connected it to the ignition circuit featuring the MC3334P IC. At first, we thought we had a goer but as we checked further we found that all was not well. At some speeds the reluctor output was not triggering the ignition circuit and so no sparks were being produced. And at low speeds, the coil charging time [dwell) was far too short. Both these factors would have made a car undriveable and hence the circuit was impractical. Our solution was to modify the Motorola circuit so that the reluctor output voltage is not critical. It involved adding four diodes and two resistors. We also discovered that the polarity of the reluctor output voltage affects the ignition timing and so we have incorporated a LED indicator circuit to show when it is correct. These modifications meant that the original circuit board is no longer suitable - a new circuit board is featured with this article. Reluctor distributor Before we go any further, what is a reluctor distributor? It is one of the three types used with solid state ignition systems. The others are the Hall Effect distributor [covered in our June 1988 article) and the flywheel pickup as used on many cars with microprocessor controlled engine management systems. A typical reluctor distributor is shown in the diagram of Fig.1. It consists of a toothed wheel on the distributor shaft, with one tooth for each cylinder of the motor. The toothed wheel runs very close to a soft iron pole piece which is wound with hundreds of turns of wire. The pole piece is attached to one pole of a permanent magnet so that the pole/coil assembly and the toothed wheel form a closed magnetic circuit. As each moving tooth comes close to the pole piece, the coil generates a voltage which swings strongly one way and then the other way, as the tooth passes and then moves away from the pole piece. The voltage waveform is akin to a flattened sawtooth and is shown in the oscilloscope photograph in this article. The beauty of the reluctor is that it is a simple passive device which is completely impervious to oil, dirt and the high temperatures in a distributor. Once the gap between the toothed wheel and the pole piece has been set, and the ignition timing is set, the reluctor distributor should not require any adjustment for the life of the car. That's a big advance over conventional distributors with points. Effectively, the only components which ever require replacement in a vehicle with solid state ignition are the spark plugs. Sometimes though, the ignition module itself fails, which is where we came in; hence this new circuit. MAY 1990 19 COIL CURRENT COIL CURRENT (b) TIME (ms) 10 15 20 25 30 Fig. 2: this diagram shows the primary coil current with and without dwell extension. In (b), the spark duration is fixed at one millisecond and so coil energy is not wasted in useless primary resonance. This allows the coil current to start from a high value for each cycle rather than from zero. High energy ignition As with our previous ignition circuits, mentioned above, the circuit described here gives a much greater spark output than is possible with conventional ignition systems, even though the same ignition coil is used. The reason for this is that the fixed dwell of conventional ignition, as set by the distributor cam and points gap setting, does not apply. Instead, at medium and high engine revolutions, the spark dura- tion is fixed at about 0.8 milliseconds. This means that for each spark, after 0.8 milliseconds has elapsed, the main switching transistor in series with the coil turns on again, so that the coil immediately begins storing energy for the next spark. The diagram of Fig.2 illustrates the benefit of a fixed spark duration. Not only does the coil have a much longer period for the current to build but since the coil does not waste energy in useless r inging of PARTS LIST 1 reluctor distributor, to suit vehicle 1 polarised 2-way connector, to suit distributor 1 PCB, code SC05106901, 102 x 59mm 1 diecast box, 11 0 x 30 x 63mm 4 6mm standoffs 3 solder lugs 1 grommet 1 TO-3 mica washer and insulating bushes 1 T0-3 transistor cover Semiconductors 1 MJ10012 NPN power Darlington (Q 1 ) 1 BC54 7 NPN transistor (02) 4 1N537475V5Wzener diodes (D1 -D4) 20 SILICON CHIP 4 1 N4002 1 A diodes (D5-D8) 1 MC3334P ignition IC (IC1) 1 red LED Capacitors 2 0. 1 µF 1 00V metallised polyester 1 .01 µF metallised polyester 1 4 70pF 1 00V ceramic Resistors (0.25W, 5%) 1 820kD 2 22kD 2 1 Ok!] 2 1kD 1 330!] 1 1000 5W Miscellaneous Automotive wire, screws, nuts, shakeproof washers, solder, heatsink compound, etc. the primary circuit after the spark is extinguished, the coil current stays at a much higher level. For a more detailed explanation of how this comes about, see our article in the May 1988 issue. The net result is that the ignition coil is able to deliver a much hotter spark, even at very high engine revolutions. By the way, our article in the May 1988 issue also gives a thorough explanation of conventional Kettering ignition, and this is essential background information for anyone interested in electronic ignition. Now have a look at the complete circuit diagram of Fig.3. The reluctor coil is connected to pins 5 and 4 of the MC3334P, IC1, via 22k0 resistors. These provide protection from excessive input voltages which may occur with a reluctor which is running with a very small gap. The leads from the reluctor are bypassed with a 470pF capacitor and one side is connected to OV (chassis) via a .OlµF capacitor. Both these capacitors help eliminate any hash picked up by the reluctor leads. Initial bias Pin 3 is the dwell voltage output from IC1 and it is stored in a 0.1µ.F capacitor. Because the Mitsubishi Sigma's reluctor has a smaller than usual output voltage, it is necessary to provide an initial bias voltage to pin 3, to make sure the circuit works over the full engine rev range and particularly at the lower speeds. This bias voltage is provided by diodes D5-D8 which are fed via a lk!J resistor from the + 12V supply. The bias voltage is fed from the diodes to pin 3 via an 820k0 resistor. By using the four diodes, the bias voltage fed to pin 3 is essentially constant at around 2.8 volts, regardless of the battery voltage which can vary widely. In fact, the circuit will work down to battery voltages of 4 volts! The fact that an engine could not be cranked at such a low battery voltage indicates that the battery voltage range is far more than adequate. IC1 stores the bias voltage from the diodes and a reference voltage detected from the reluctor via an in- .----------------------+12V SWITCH VIA IGNITION 330f! , __ _ HTTO OISTRIBUTOR 820k IC1 MC3334P 4x1N5374 (75V 5W) .,. CASE B RELUCTOR IGNITION SYSTEM ELJc C 0 0 B VIEWEO FROM BELOW Fig.3: the key components in the circuit are the Motorola MC3334P high energy ignition IC and the MJ10012 high-power Darlington transistor (Ql). The Darlington transistor switches the heavy currents through the coil. The string of four zener diodes protects the Darlington against excessive coil voltage if a spark plug lead becomes detached. ternal diode. It is this dwell voltage which determines how long the output transistor Ql is conducting, at the various engine speeds. We've already mentioned that the spark duration at medium and high engine speeds is around 0.8 milliseconds. At cranking and low engine speeds, the spark duration is longer and may be up to 3 milliseconds long. This actually has the effect of slightly reducing the heat dissipated in the coil while not having effect on the available spark energy. The output of ICl, pin 7, turns Darlington transistor Ql on and off. Pin 7 is actually the collector of an internal transistor and it is supplied with current via the external 1000 5 watt resistor. When pin 7 is pulled low, all the current through the 1000 resistor is shunted away from the base of Ql which is then turned off. When the internal transistor is turned off, all the current passes into the base of Ql which then turns fully on. Ql is an MJ10012, which is a very rugged high voltage Darlington transistor with a collector current rating of 15 amps peak. It is designed specifically as a coil driver in automotive ignition systems. Never- We obtained this Mitsubishi Sigma distributor from a wrecker's yard for $100. The rotor button has been removed -to show the toothed wheel. This has four teeth, one for each cylinder of the motor. theless, while it is a rugged device, it is possible that it could be damaged if a spark plug lead became disconnected. Zener diode protection If a spark plug lead does become disconnected, the coil secondary voltage can rise to very high levels, perhaps 40,000 volts or more. This can do two things. First, it can damage the coil itself by internal flashover and second, because the primary voltage also becomes high, say 500 volts or more, it could damage the MJ10012. MAY 1990 21 which needs to be explained involves Q2 and the LED. The base of Q2 is connected to pin 7 of ICi so that Q2 turns off every time Qi turns off. Normally, Q2 is on and the LED is alight. When Q2 turns off, for the same 0.8 millisecond period as Qi, the LED is extinguished momentarily and that tells you the firing point of the reluctor. This enables you to do an initial timing of the reluctor, and ensure that the reluctor coil polarity is correct before the ignition coil is connected. Spark plug gaps The high-power Darlington transistor is installed on the outside of the diecast case and fitted with a plastic cover to prevent shorts or "tingles" from inadvertent contact. To protect against this situation, we have included a chain of four 75V zener diodes between the emitter and collector of Ql. With these in circuit, the coil primary voltage is limited so that no damage can result. In fact, while you may expect the voltage to be limited to 300 volts (ie, 4 x 75V), the actual limiting figure is close to 350 volts because the zeners do not turn on really sharply. In our previous ignition circuits featuring the MC3334P and MJ100i2, we specified four 75V iW zener diodes, type iN4761. In most cases these have worked entirely satisfactorily and we have not heard of an MJ100i2 or an ignition coil failure. However, the iN476i zeners in our own prototype of this circuit failed when we deliberately opened up the spark gap on our bench setup. And we have heard of i W 75V zeners failing in a number of units in the field. Therefore, to give a greater margin of safety, and thus extra reliability, we are now specifying 5 watt zener diodes, type iN5374. We strongly recommend that they be used in the previous circuits, too. Trigger point indicator The last feature of the circuit The lower trace on this CRO photograph shows the 35V p-p output from the reluctor pickup. Above this is the coil primary voltage waveform which has a peak to peak voltage of 350V (CRO sensitivity l00V/div; horizontal timebase lms/div). 22 SILICON CHIP In the past it has been common practice by car enthusiasts, when they have fitted electronic ignition, to increase the spark plug gaps. This was done to take advantage of the higher spark voltage and thereby obtain a longer spark "path". We don't recommend this practice. It places much greater voltage stress on the car's high tension components; the coil, distributor, spark plug leads and the spark plugs themsevles. So there is more likelihood of a high tension failure. Construction The circuitry for our high energy ingition system is housed in a small diecast box. It may not look "high energy" but it is. The box measures 110 x 30 x 63mm and provides what little heatsinking the main Darl- Mount the four zener diodes with a loop in one lead to provide stress relief as the devices warm up. The remaining parts should all be installed without stressing their leads and should move freely in the PCB before soldering. I. ~~; ~1.m•• ~ ~ LED. 1f-"'l ·- ~ 07 ~ £2) 06 IGNITION SWITCH . ~ ...... 03 ~ . . ~ I' - - - -- - -- -- -- - - -- Fig.4: here's how to install the parts on the PCB and run the internal wiring. All wiring from the board should be run using 4mm auto cable which has a generous current rating. The case of the Darlington power transistor must be electrically isolated from the metal case. Problems? ... and you don't have our NEW 1990/91 148 page electronic parts and accessories catalogue ... Its our latest TRADE catalogue for the consumer ARISTA ... Your one-stop problem solver. ----TRANSISTOR 0 0 CASE ©-INSULATING BUSH <at>::::i)-SOLDER LUG <at>-WASHER <at>....--SPRING WASHER <at>--NUT Fig.5: the Darlington power transistor is electrically isolated from the case using insulating bushes and a mica washer. Smear heatsink compound on the mating surfaces before bolting the assembly together, then use your multimeter to check that the transistor is correctly isolated. ington transistor needs. Under normal operation, the transistor and the case become warm but not hot; or no hotter than the surrounding metalwork underneath the bonnet. All the circuit components, with the exception of the MJ10012 transistor, are mounted on a printed circuit board measuring 102 x 59mm (code SC 05106901). The wiring diagram is shown in Fig.4. Note that the diecast box is the only type that we recommend. This is because it is splashproof, rugged and provides heatsinking for transistor Q1. We don't recommend folded metal cases because they are not splashproof. Begin construction by mounting the PC pins onto the PCB, then install the rest of the components, according to the wiring diagram. Mount the 5W resistor so that it is raised about 1mm from the PCB surface to allow cooling. The four zener diodes should be mounted with a loop in one of the leads to provide stress relief. For the remaining components it is important to insert them into the PCB without stressing their leads. The component leads should move freely in the PCB holes before they are soldered. Once assembly of the PCB is complete, work can begin on the diecast box. Drill holes for the corner mounting positions of the PCB, a cord entry in the side of the box large enough for the grommet, and finally holes for the earth terminal, transistor mountings and the base and emitter leads. The transistor is mounted on one side of the case with the emitter lead located near the relevant connection on the PCB. The transistor is mounted using a ... Stylus .. . ...Plugs, Jacks and Sockets ... .. .Batteries .. . ... Cable .. . .. .Tools and Technical Aids .. . ... Plug and Power Packs .. . ... Car/Auto Accessories .. . ...Boxed Hi Fi Speakers .. . ... Raw Replacement Speakers ... ... Speaker Accessories ... ... Telephones and Intercom .. . . .. Public Address Accessories .. . ... Security and Alarm Accessories .. . .. .TV/Video/Antenna Accesories .. . ... Videocam Accessories ... ... Audio Accessories ... ... Headphones ... ... Computer Accessories .. . ... Microphone Accessories .. . ... Mixers, Amplifiers, Equalizers ... Just about anything you want ... Get your catalogue complete with "Recommended Retail Prices" free from your local ARISTA dealer or send $2.50 P & H and your return address to: ARIST~ ELECTRONICS PTY LTD PO BOX 191, LIDCOMBE, NSW, 2141 MAY 1990 23 Our test setup used an old sewing machine motor to drive the distributor shaft via a flexible coupling. An electronic speed controller varied the speed of the motor so that performance could be checked over a wide rev range. mica washer and insulating bushes to electrically isolate it from the diecast case . The method of assembly is shown in Fig.5. You can mark the holes for mounting the transistor using the T0-3 mica washer as a template. After drilling, remove any burrs using a larger diameter drill. With the heatsink area (ie, where the transistor mounts onto the case) free of any metal swarf or grit, smear a thin layer of heatsink compound onto the transistor mounting base and the mating area on the case, before placing the mica washer in position. When the transistor is screwed down, check that it is completely isolated from the case by using a multimeter (switched to a high "Ohms" range) or a continuity checker. The PCB is mounted on four 6mm standoffs within the case. We recommend using shakeproof washers on all screws to ensure that they don't become loose. The wiring to the power transistor and to the various external connections should be via 4mm auto cable, soldered to the PC pins. Use 1-metre or longer lengths of wire to provide the chassis, points, coil and battery connections to the circuit. Installation Choose a convenient and well ventilated spot in the engine bay, ,ol O 0 T'" 0 O'> <.O 0 T'" I.() 0 (.) (/) Ch ,~ Fig.7: this is the full size artwork for the printed circuit board. 24 SILICON CHIP 10:L12V FUSE BALLAST RESISTOR N/0 HT 12V RELAY .,. +12V TO IGNITION CIRCUIT TO COLLECTOR OF 01 Fig.6: if making a direct connection to the ignition switch is too difficult (in cars with the ballast resistance in the harness), you can use this relay hook-up to make a more convenient connection to + 12V. away from the heat of the exhaust manifold and clear of any possible splashing from water. If you can, choose a position reasonably close to the coil so that long wires can be avoided. For our prototype, we were able to mount it simply with two large self-tapping screws in one side of the case and into a bulkhead near the wheel well. It was just a matter of having suitable holes drilled in the case and bulkhead. The two screws are then used to secure the unit. A plastic case fitted over the power transistor is a good idea - J because it prevents any possibility of shorts from stray tools. It can also avoid the possibility of a "tingle" to any unsuspecting mechanic working on the car while the engine is running - and that could include you! After mounting, the electrical connections, can be made. The final connection for the transistor ignition is to the + 12V supply which comes via the ignition switch. In some cars this is accessible at the + 12V side of the coil ballast resistor. However, some Ideally, the high energy ignition module should be installed in the coolest available spot underneath the bonnet. Use 12mm x No.to selftapping screws to secure the module to the firewall. vehicles have the ballast resistor as part of the wiring lead to the coil and this means that the + 12V connection must be made at the fuse panel. Once the ignition system is installed, the reluctor polarity and static timing can be tested. Turn the engine by hand until a reluctor tooth is close to the pole piece. Then loosen off the distributor clamp and rotate the distibutor housing back and forth so that the tooth moves past the pole piece. Each time the tooth moves away from the pole piece, the LED should blink. If not, swap the connections to the reluctor coil and try again. You can now fit the lid to the case, connect the coil and replace the distributor cap. The vehicle should now be started and the ignition timing checked using a timing light in the normal way. ~ VBATT 4-24 Vdc RBATT 300 CflLTER 0.1 I -=- 6 Vee RDRIVE 100 Ignition Coil Primary 8.0 mH Power C1' 470 RL 10 k Output and OVP OUT Current Limit B c2• J:0.01 Dwell Reference •Optional Pans for Extended Transient Protection Buffer Sense Rs 0.075 -=- .. A 350 V zener clamp is required when using the standard MJ10012 . This clamp .is not required if a selected version with V(BR)CEO(sus) " 550 V is used. -=- MC3334 Sense 2 1 Power Ground Ground~------~ Fig.8: this is Motorola's suggested circuit for the Delco distributor. It requires several modifications so that it is also compatible with the distributor fitted to Mitsubishi Sigmas. MAY1990 25 lnVl'IIIV..JUr\ l Vr\11 LLLV 111\..Jl 'U VVVn I v n , I LLL V TRON ICE JAYCAR TR ONICE JAYCAR TRON IC~ JAYCAR TRON IC~ JAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR I I 1v,., v ........ , , , v, , , , •- .... v ' ' . ..... . ............., , , ...,., " , •-• ._...,,, ,....,,.,...,. ..... -.,,, , ...,, ,, , ._ ........ ...,,, , ..... , . ............. , , , ...,.,", •-L'-..., • 1 • ...., ... ..........., , , ...,.,~ , ' .... L ... ..... ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAll [ L l:CTRONICSJA YCAR ELECTRONJCSJAYCAR ELECTRONJCSJA YCAR ELECTRONICSJAYCAR ELECTRO NICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAll El ECTRONICSJAYCAR ELECTRONICSJAYCAR ELFCTRONICSJAYCAR ELECTRONICSJA YCAR E'LECTRONICSJAYCAR ELECTRONICSJAYCAR ELFCTRONICSJA YCAR ELECTRONJCSJAYCAR ELECTRONICSJA YCAR I 1 , v , ,. , .......... ...,.... , ..... '"'n ._._.__.._, , fl\,,Jllt l \.,.:>JAYl;l-jrt ELECTRONICSJA YCAR ELECTRONICSJAYCl)it ELECTRONICSJAYCAR ELECTRONICSJAYC/l<t ELECTRONICSJAYCAR ELECTR'.:JNICSJAYC/l<t ELECTRON lr.SJAYr.AR ELEC:RONICSJAYC/ICt T Tf Tf Tf Tf TF TF TF TF l T Tf TF Tf Tr Tr SWITCHMODE POWER SUPPLY Unbelievable Distress Stock Purchase Unbelievably cheap but there's a catch! These were included in our 1987 Catalogue and were selling for $39.95 each. We have purchased the entire quantity from the importer who was told to clear all stocks at any price! The unit is not the most accurate in the world. but it will give you some idea of the pH and Chlorine levels. The two probes are inserted in to the water to be tested. An instant reading of the Chlorine level and pH value is given on the panel meter display. • Ideal for parts also. The meter is worth $10 alone. We have obtained a quantity of new (removed new from brand new equipment) computer switchmode type power supplies. They have outputs of +5V 2A. +12V 30mA.12V 30mA. & 12V 2A. The problem is that they are 11 OV powered and NOT 240V. You can use them for parts at this bargain price. Cat. MP-3000 ■ Cat.OM-6135 WAS $39.95 each NOW ONLY sg 95 • sg.95 ·· Machine Pin Type Solder Type EXPERIMENTORS PLUG PACK BARGAIN 'N.T.C. GLASS THERMISTORS Don't miss this one. Prima,y • 220V 50hz (will work OK on 240V) lead length 1.Bmt long - bare ends ( no 240V plug supplied). Seconda,ys - 16V AC at BOOmA - WAC at 1.5AMP Lead length 1.7mt long terminated in a strange plug Supplied in a maxi box style. Measures 75 (WI x 85 (LI x 60 (H)mm These have been extremely hard to obtain lately. We have obtained a small quantity of two varieties in limited quantities. Last prices available for these were $25 each in small quantities at wholesale levels. Full specs available on rec;uest 20 Pin normally 4~ each Now 16 for $2 Save $5.68 Cat No. PI 6504 28 Pin normally 7ot each Now 14 for $2 Save $7.80 Cat No. PI 6507 40 Pin normally 7ot each Now 10 for $2 Save $5 Cat No. PI 6508 A25TYPE 1-9 $5.95 1049$5.5 Directly heated beads type. Nominal resistance 200k ohm at 2s0 c:i20%. Bead in gas filled glass envelope suitable for amplitude control, pulse suppression, time delay and low frequency power measurement Cat. RN-3460 sg.95 {n X (] 1 l Indirectly heated bead type. Nominal resistance 100k ohms at 25°C :i20%. Applications include amplitude control . gain control. true RMS power measurements. timing devices and as remotely controlled variable resistors. Cat. RN-3462 16 Pin normally $1 .50 each Now 3 for $2 Save $2.50 Cat No. PI 6456 18 Pin normally $1 .65 each Now 4 for $2 Save $4.60 Cat No. PI 6458 20 Pin normally $1 .90 each Now 3 for $2 Save $3.70 Cat No. PI 6460 22 Pin normally $2 each Now 4 for $2 Save $6 Cat No. PI 6462 24 Pin normally $2.30 each Now 3 for $2 Save $4.90 Cat No. PI 6464 28 Pin normally $2.60 each Now 4 for $2 Save $8.40 Cat No. PI 6466 40 Pin normally $3.25 each Now 3 for $2 Save $7.75 Cat No. PI 6468 Techlite Bulbs • Low Voltage Lighting System This is the same as the 'firefly' lighting you saw all over the count,y during 1988 Bicentenna,y. Save $20 over the original system we sold in 19BB. The cable simply pushes into the lugs under the globe housing and a slide clip arrangement holds the bulb firmly. 10 BULBS/BASES Cat SL-2800 $12.95 CABLE TO SUITcatWB-110055~ metre POWER SUPPLY 1 AMP TRANSFORMER Cat. MM-2002 (up to 25 globes) $10.95 2 AMP TRANSFORMER $16.95 s12.95 1 .5 Volt Battery Testers TURNYOUR SURPLUS STOCK INTO CASH!! The latest in batte,y testers. Consists of a ve,y flexible piece of plastic with a conductive strip on the rear. Simply place over the batte,y terminals and the indicator will show if the batte,y is good. reasonable or bad. Re-usable. Eve,y desk drawer. workshop. toolbox neals at least one. And at the price who cares. 5 different designs available. Cat. SB-2350 4f Tf . TI TI iliiiiii~i continually on the lookout for sources of prime quality merchandise. , -- I nun1n..,vuM I V/\n CLCL. 11-t Vfl,jlL, i:).JA fl...,1-\ H C L CL. I_H Ul'l l l;~A Yl.,.,/-\H t:.Lt:. ..L I HUNIL,b.JAY(..;AH T J-!; v 11t1vvuM • unn L L L'-' 1 nv, ~ rvvuM 1 vMn cu: v TRON ICSJAYCAR TRONICSJAYCAR TRONICSJAYCAR TRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRON ICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR $2 or Jaycar will purchase your s urplus stocks of components and equipment. We are TOl'lf\ ll r ~ IAVrAo r::-1 r::-rTO f"\ l\llf"~ I AVf"'AO Cl Cf'TD/"\11.llr"C' I AVrA D ELECTRONICSJAYCAR ELEClRONICSJAYCAR EL[CTRONICSJAYCAR ELECTllONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAH EL[CTRONICSJAYCAR [LECTRONICSJAYCAR C l 1: r , 01""\ll. ll r'C' IA VrAn C'I r,-.Tnr.... 11 ,...r ,,.v,...,.,, FLECTRONICSJAYCAR lLECTRONICSJAYCAR LLEClRONICSJAYCAR ELECTRONICSJAYCAR ,-, ,-,.... ....... ,.. .. ,,,..,..., ... ,,,., .. ..-. CALL MARK HARRIS OR BRUCE ROUTLEY NOW ON (02) 747 2022 ~ ~ ; ; ; ; ~ ~ ~ ~ ; ; ; ~ ~~ ON ICSJAYC~ ON ICSJAYI' tLtt..; J HUNIC&!A YCAH tLECTRONICSJAYCAR ELECTAON ICSJAY ~ ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAY ' El rcTRON ICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAY , ELEClRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYC · ELECl RONI CSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYC/1 : .................., .... . ,, ....,_ .. · ·- • - -- - - - - ... - (CAR (CAR (CAR rcAR YCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRON ICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAH ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR l:Ll:Cl HONIC::;JAYCAH ELECTRONICSJAYCAR ELECTRONICSJAYCAR EL ECTRONICSJAYCAR ELECTRONICSJAYCAR tLtC I HUNIC::;JA YCAH ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR t:Lt:C I HUNIC:SJA YCAH ELECTRONICSJAYCAR El.ECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR t:Lt:C I HUNIC:S ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAR JAY CAR JAYCAR ELECTRO~ ELECTRO~ ELECTRO~ ELECTRO~ ELECTRO~ RON .RON .ROI\ FULL DETAILS SEE PAGE 61 -1990 JAYCAR CATALOGUE UHF Wireless Security System ·Rol\ ·Rol\ Just imagine a security/alarm system that does not need wires to connect the PIRs, window/door reed switches, personal remote control and optional remote keypad. The only wiring required is to connect to a horn speaker. NEW ROI\ ·Rol\ ·Rol\ ·Rol\ UHF 303MHz Microprocessor Control Wireless Security Alarm System .ROI\ ·Rol\ ·Rol\ -ROI\ COMPLETE SYSTEM includes 1 x Control Panel 1 x Passive Infra Red Detector/Transmitter 1 x Door/Window Reed Switch/Transmitter 1 x Hand Held Remote Control/Transmitter 1 x Horn Speaker - 10 watt/wired 1 x 240V AC adaptor 1 x 1.2Ah Back-up Battery 1 x Set of batteries for all transmitters ·Rol\ -ROI\ -ROI\ rHo~ ·Ro~ rRO~ fROI\ ·nol\ ,RO~ ·nol\ Cat. LA-5200 rROI\ ' RO~ ' RO~ ONLY $599 OPTIONAL EXTRAS •Door/Window Reed Switch - Wireless Cat LA-5210 $69 rRO~ • Wireless Passive Infra Red Detector Cat. LA-5205 $149 • Wireless Remote Keypad Cat. LA-5215 $129 fROI\ [ RO~ TROI\ r ROI\ [ ROI\ f ROI\ HO~ ROI\ ~ROI\ • Hand Held Remote Control - Wireless Cat. LA-5208 $59 ECONOMY MODEL MULTIMETER FREE POWER WITH SOLAR CELLS 0.45 VOLT MODULES Ideal as a first meter. Compact enough to fit into the glove box in your car. • 2,000 ohms/volt • Mirror scale to prevent parallax error • Complete with test leads and instructions • DC & AC volts 0-10, 50. 250 & 1000V • -10 to +22d8 • 0-1 OOmA current • 0-1 M ohm (2 ranges) • Measures 90 x 50 x 80mm • Battery included (1101\ Ideal for experimenters. Connect in series or parallel if you wish. Terminal strap enables easy connection to other cells. TWO HANDY SIZES 0.45V 400mA Size 96 x 65 x 6mm i:~g~ RO~ ·riol\ ·Rol\ ·riol\ Cat. ZM-9005 .ROI\ rRol\ s3_95 ROI\ fROI\ ROI\ Cat. OM-1001 $18.50 NORMALLY MAY ONLY $15.50 SAVE $3 50 for $5 Cat ZR-1009 HORN SPEAKER Fully weatherproof. Suitable for PA, intercom. security systems. etc. 10 watt 8 ohm. Cat. AS-3180 NORMALLY $13.95 MAY ONLY s11.95 SAVE $2 SPIROMATIC INDOOR ANTENNA For prime reception areas, site on top of your TV. Popular spiral design. 300 ohm cable supplied. Cat LT-3100 NORMALLY $9.95 MAY ONLY S&.95 SAVE $3 6"TWINCONE WIDERANGE Freq. Resp. Sensitivity Impedance Power Magnet Weight Cat. CE-2320 60-15kHz 89d8/1mt 8 ohms Owatts RMS 5.3oz ~YCAR W CAR W CAR W CAR ELECTRONICSJAYCAR ELECTRONICSJAYCAA ELECTRONICSJAYCAR ELECTRONICSJAYCAR fROI\ ·Rol\ 1 :·Rol\ ·riol\ NORMALLY $13.95 MAYONLYS9.95 SAVE $4 -ROI\ ·riol\ .ROI\ ·Rol\ ROI\ 10+ $9.50 ea ·riol\ -ROI\ ·riol\ QUALITY DISCS AT UNREAL PRICES Another Jaycar direct import. All disks are supplied with envelope, index labels and writeprotect tabs. Remember. these disks might be cheap but they are good quality. We are so impressed by the quality we are happy to offer a lifetime guarantee 0s c . ·;;- _~~~ ]::\••••••••••·•••>• ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAA ELECTRONICSJAYCAR mor $16.95 for 10 S_A_V_E_$_1_0_______________ F ORMAT TO 1.4Mb! lfyourcomputerhasthenewfonnat ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAA ELECTRONICSJAYCAR ,p -~~~·~;:;;~ ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR JAYCAR JAYCAR JAYCAR JAYCAA mor rn01 TROI TfRROOII TROI § ~~g $34.95 ELECTRONICS ELECTRO tJICS ELECTRONICS ELECTRONICS ' ROI\ ;~g~ ~~g~ ~ 31/'l' MF2DD 135TPI DOUBLE SIDED/DOUBLE DENSITY Cat. XC-4736 NOW •Rol\ fROI\ $15.95 for 10 S~E~ Cat XC-4732 Cat.XC-4738 ,RQI\ -ROI\ mo" 51/4" DSHD 96TPI DOUBLE SIDED/HIGH DENSITY ·;::;;;;~-;;;.· ·1101\ ·Rol\ fROI\ $6.50 for 10 vAT1 ·L1...Lv ·,·.-v,..i('iiivv,.JM·1v·n, , LL LVt 11v1-.,vvur., vnn LLLV 1nv1-.,v~"' , vnn LLLV I nv 1..,11..,vuM 1\.,1"\n C.LCV 11"'\v1..,1v.:, .Jr. 1 vM1, '-'-'--V ' ' ' '--''"''-"'"""",..... 1 vr.r, ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAA ELECTRONICSJAYCAR :·Rol\ -ROI\ -ROI\ NORMALLY $6.95 MAY SPECIAL s3.so 1/2 PRICE .-r;;~ -- --, ~~g~~ m: s79 Allows you to easily switch between : 51/4" DSDD 48TPI DOUBLE SIDED/DOUBLE DENSITY 2 inputs to your TV. Cat. XC-4730 Cat LT-3018 \- ~YCAR ELE' 10+ $5.00 ea ; 1101\ rHQI\ : ROI\ CROI\ ' ROI\ TV GAME COMPUTER SWITCH 10+ $10.95 ea ss.so Quality cell with aluminium picture framing around the edges. Resin covered. Size 327(L) x 165(W) x 18mm thick. Cat. ZM-9009 Cat. ZM-9007 1N4003 1A 300V Cat. ZR-1003 50 for $2.50 \ ROI\ ,-ROI\ fROI\ Size 96 x 65 x 6mm DIODE MADNESS 1N4007 1A 1000V rRol\ 0.45V 600mA ELECTHONICSJAYCAR ELECTRONICSJAYCAR ELECTHONICSJAYCAA ELECTRONICSJAYCAR 1...1..1........:TRO ELECTRO ELECTRO ELECTf10 ELECTRO n CLC...., 1 nvt'l1v.::,..,1,-..11...,Mn ct..CV I t1VPm,..;-=:,. .JA n ..,J-\.n C L C'v I nV1'i 1.._,.:,,.u·'\ TV/-\ M CLCV I nVl'IIV.;::,.,JI-\ T \.;f-\M CLC V I MVl..,IV->,JJ-\ lVJ-\.M CLCI.., I H.Ul'llll..,::>.JA TL,AH t:LCL, I HUNIL,~AYl,;AH t. L t.L,; I HUNJC:s.JAYCAH tU:.C f RONIC~ R ELECTRONICSJAYCAR ELECTRONICS JAYCAR ELECTRON ICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR R ELECTRON ICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR R ELECTRONICSJA YCAR ELECTRONICS.JAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR R ELECTRONICSJAYCAR ELECTRONICS.JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTR ELECTR ELECTR ELECTR ELECTR ELECTR ELECTR ELECTR ELECTR ELECTR Ref: Silicon Chip April ·90 Ref: EA May 1990 ELECTR This magnificent switchmode type laboratory power supply has great professional features ELECTR Replace those expensive fN batteries with an economical 1.5V D cell. Lasts much longer and but costs around 1/2 of inferior built up units. ELECTR saves you the cost of too kit in no time. Shortform kit - PCB. potcores, battery holder. heatsink This kit features high efficiency toroid power transformer, professional high resolution 10ELECTR and all electronic components supplied (excluding optional receiver parts). No box or box turn wire wound voltage control potentiometer, latest I.C. technology, excellent line load ELECTR hardware supplied. regulation. low ripple voltage, apart from a smart plastic case! (for more information see ELECTl3 specs below). ELECTR Cat. KA-1724 The Jaycar kit is complete down to the last nut and screw as well as all hard-to-get I.C.'s. ELECTR ELECTR CatNo. KC-5073 ELECTR ELECTR Specifications ELECTR Type: Dual tracking with switchmode pre-regulators for high efficiency ELECTR Output Voltage: 0 to+/-flN ELECTR 1.7Afrom0to87V; 1.5Aat91V; 1Aat100V Output Current: ELECTH Box not supplied Tracking Accuracy: Better than 30mV ELECTR Load Regulation: Better than 500mV at +/-V and 1A ELECTR Line Regulation: Better than +/-5mV for mains voltages from 220-260V AC ELECTR Ripple output: Less than 3mV p-p at full load ELECTH Protection: Fully protected against output short circuits and forward ':L[CTH Ref: Silicon Chip April '90. At last a VOX (Voice Operated Relay) that does not cut off the first and reverse voltages connected to the output fuse protection for the cLECTR bit of speech! This clever project uses an acoustic delay to prevent the common fault in all transformer. cLECTR ' but the most expensive VOX circuits - the lOmS or so of that is lost by relay operating time. It :: LECTR• may not sound much but it is very annoying and a long time in speech terms. ::LECTR This kit is supplied by Jaycar in a shDft form. i.e. without case, front panel, plug adaptor etc. ::LECTR This saves you over $20 on the price otheiwise. as we believe most of these projects will be :: LECTR• built into other equipment anyway. All other parts (including all PCB parts) included. : LECTRC Cat KC-5074 : LECTR• : LECTR< Specifications Signal delay: 16.4 miliseconds • Clock frequency: 15.7kHz • Frequency : LECTRI response: 100Hz to 43kHz within (pm) 3dB • Maximum output signal : BOOmV RMS • : LECTRC Maximum input sensitivity: 0.7mV RMS (to actuate relay)• Harmonic Distortion: : LECTR <0.5% at250mVand lkHz<l.5% at BOOmVand lkHz • Signal to noise ratio: (ms) 66dB : LECTRC unweighted with respect to 500mV RMS at the output , LECTRC : LECTRC ' LECTRC :LECTRC :LECTRC :LECTRC Ref: Silicon Chip March 199U Ref: EA Dec 1989/Jan 1990 :LECTRC Comprehensive battery charger for GEL batteries. Charges NEW - upgraded design - now gives ,LECTRC both 6 & 12 volt batteries. Charging rates: · 1.2Ah (250mA); 140W rms channel into 8 ohms. 'LECTRt 2.5Ah (520mA); 4.5Ah (900mA); 6Ah (1 .2A); 15Ah (3A). Dual toroidal transformers supplied. ,LECTR< Charges our range of GEL batteries. Includes PCB and all Cat. KA-1725 ,LECTR board components . No box or front panel. Transformer not ,LECTR supplied: 1.2Ah-4.5Ah use MM-2008 $18.95 Of 6Ah-15Ah :LECTRC use MM-2000 $37 .95. ,LECTRC Cat. KC-5071 :LECTRC :LECTRC 'LECTR< :LECTRC .LECTRC :LECTRI :LECTRC Another surplus buy. If you are a gardener you have probably :LECTRI :LECTRI seen the moisture meters in nurseries that indicate the moisture .LECTRI level in soils for about $16. .LECTR< This unit does that, plus more: LECTRI • Indicates moisture level in soil • Check proper PH value of the soil LECTRI • Check strength of light (LUX)• Also includes a thermometer in F/C LECTR• With all these features you would expect to see this in nurseries for $30LECTR• LECTR• $40. LECTR• We have a limited quantity available for only $14.95. LECTR• about l(Z price or less. Don't miss out. LECTH Cat. QM-6136 LECrn LECTR LECTH LECTR• ELECTRONICE ELECTRONICE ELECTRONICE ELECTRONICE ± 50V (0-1 00V) 1.5A Dual Tracking Power Supply Kit A 1.5 to 9V DC/DC convertor $229 ONLY $19.95 Non First Syllable Dropped Off VOX Relay Kit Only $59. 95 LEAD ACID BATTERY CHARGER PRO SERIES 1 POWER AMP· 140 WATTS RMS PER CHANNEL $599 $69 Plant Checker ONLY $14.95 t~gi:: t~gi: LECTR• ADELAIDE STORE ~!g~~ NOW OPEN t~gi: 190 Wright St re e t Ph •■ (OS) 2 31 7355 LECTR LECTR LECTR LECTR LECTR LECTR LECTR LECTR LECTR Childr_ en are encouraged to learn to compose music, spell, learn maths and play strategic games all on their own without supervisionll Cat. XC-3050 NOR MALLy $69 SAVE $30 ONLY $39 - ~~2~~ 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. MemoryTune Math Quiz Multiplication Quiz Am I Correct- math practice Begins with· first spelling Spelling Guess That Letter-auto or program manually Guess That Word- auto or program manually Letter Finder Number Finder LECTRO ~il~ll~l~ll~l~!i!~l.;~~~~i;;~~~~;.;'9!~~~~~i!i~- iiililillECTRO LECTR iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiili LECTAUN IC~JAYt;AH A Yl..,AH l:Lt:J, ., I HUNIL,".JA Tl.,1-\H CLCL, I MVNIL,.:,.Jf\ T\....,M.11 CLC V LECTRONICSJA YCARAYCAR LECTRONICSJAYCARAYCAR LECTRONICSJAYCARAYCAR LECTRONICSJAYCARAYCAR ELECTRONICSJA YCAR ELECTRONICS-JA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR I MU l,,.ll..,.-:,,..,J/'\ TVl'\M CLCV I MVl'I I VV.JM IVMn L.:t..u., 1 MVl'll'v.;>Jf"\ I ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR vr,n ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR LLLV Inv•"•'-'~'"'-, '-inn L'-'-'--', nv ELECTRONICSJA YCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR LECTRO ELECTRO ELECTRO ELECTRO ELECTRO AYt;AH l::.Ll;:;c.; I HU NlC ~ J AY L,J.\ H, C LC L.. I M V l " ll....,.:'I .JM l\..,F"\1"1 LLL ...... I I H.J • • • Uu..,, ' ' '-1¥ "' ............... . ' ,...,, ~ , .., ......., . ' ..... " • ._._.__.' · - · AYCAR ELECTRONICS AYCAR ELECTRONICS ~ YCAR ELECTRON/CS ~ YCAR ELECTRONICS JAYCAR ELECTRONICSJAYCAR JAYCAR ELECTRON /CSJAYCAR JAYCAR ELECTRONICSJAYCAR JAYCAR ELECTRONICSJA YCAR ELECTRON/CSJAYCAR ELECTRONICSJAYCAR ELECTRON ICSJAYCAR ELECTRON/CSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRON/CSJAYCAR 30 Piece Engineer's Driver Set At last! A driver set incorporating those obscure shaped heads! Have you ever needed recently to service an electric tool? Chances are you would not have been able to do so because the screws holding the appliance together had strange shaped heads. Well now you can with our 30 piece driver set! This set contains all the driver bits you are EVER likely to encounter. (See below). Basic to the set is an 8 1/2" Chrome-Vanadium driver which will accept any of the 28 hardened steel bits supplied. They are held into the socket of the driver by a small magnet - so you can use the driver in any position. The screw together hollow handle will hold several tips so you don't haveJo take the whole set with you into the field. There is a lip here to suit almost any screw/nut you may come across. Here's what you get: • 5 slotted bits 0-1, 3-4. 5-6. 8-10, 12 • 5 hex bits 3/32", 5/64", 7/64", 1/8", 9/64" • 4 Philips bits No 0, 1, 2 & 3 • 4 square recess bits No 0, 1, 2 & 3 • 6 Ton< bits T10, T20, T25, T30, T40 • 2 Pozidrive bits No 1 & 2 • 1 x 1/4" drive socket adaptor • 1 x 1/4" drive hex bit holder And it's all housed in a sealable tough plastic case. Cat. TD-2000 ··--~· .. - · ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJA YCAR .. - - . ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRON/CSJAYCAR $59 .9 ---------- w la" woofer $99 I •: 1O" woofer 1 I 4/8 ohm 160W rms Cat. CW-2143 $149 1 4/8 ohm 120W rms Cat. CW-2142 J12" woofer · ·:rn ,m: :: $1 79 $1 79 IDome midrange J4/8 ohm Cat CM-2090 $4 7 .so IDome tweeter ) 4/8 ohm Cat CT-2010 $29.50 I FX2242 POTCORES Normally $15.95 pr MAY SPECIAL I s10 pr I I Cat. LF-1265 .. ':: MOTOROLA KSN 1141A PIEZO TWEETER 400W RMS i : Brand new Motorola Pt1Nerline horn.Includes a protection circuit internally which allows the new horn to handle 400W rms. It uses a miniature light bulb and a PTC resistor. Under extreme high power surges, the PTC opans up allowing the speaker to continue to play at a somewhat compressed power level. The resulting product is virtually blow-out proof. Replaces the KSN1025A. See catalogue for specs. 3 year warranty. Cat. CT-1912 $37.95 I I I • I : ELE( im< l ELE< ~ • Inductance • Capacitance • Frequency • Temperature • Peak hold • Logic See catalogue for full details Cat. QM-1475 $69 14/8 ohm 200W rms Cat CW-2145 ·· · ··· ····················· 3. 75 DIGIT 4000 COUNT 39RANGE ::: • High Quality ::) • Dual Impedance ·•·· : See catalogue for full specs. CW-2140 . . -- Probe Type Digital Multimeter 3 1/2 Digits• Manual or Auto Range with Logic Probe ( RE/Sponse SPEAKERS : I • High Power 1 4/8 ohm BOW rms Cat . -· . F.LECTRON /CSJAYCAR ELECTRC ELECTRONICSJAYCAR ELECTRC ELECTRONICSJA YCAR ELECTRC ELECTRONICSJA YCAR ELECTRC l ELEC 1 ELEC 1 ELEC l ELEC 1 ELEC 1 ELEC 1 ELEC This fantastic 3 1/2 digit meter is actually easier to use than a conventional hand-held unit. ELEC The readout is in the body of the 'probe' itself so you don"t have to avert your eyes to get a ELEC circuit reading. The unit has most of the features of conventional meters as well! ELEC Logic Probe Bonus. This TTL/CMOS compatible feature will test logic 'HI' or logic 'LO'. The ELEC circuit is protected to 250V. All electrical symbols are shown in the large 142mm x 18mm) ELEC window. 1 ELEC Cat. QM-1420 1 ELEC 1 ELEC 1 ELEC 1 ELEC ELEC 1 ELEC ELEC ELEC 1 ELEC ELEC 1 ELEC ELEC $19.95 ••· 6" woofer -· ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJA YCAR ' i :: ·: ELE< ELE< ELE< ELE< ELE< ELE< ELE< ELI: < ELE< ELE< ELE< l ELE< ELE< ELE< ELE• ELE• ELE• ELE• ELE• ELE• ELE ELE l ELE l ELE l ELE l ELE l ELE l ELE ELE ELE ELE ELE ELE ELE ELE ELE ELE ELE ELE ELE ELE ELE ELE ELE ELE ELE ELE ELE ELE ELE 111 MAIL OR POST & PACKINO MAIL ORDER VIA HEAD OFFICE P.O. Box 185 Concord 2137 ~ 115 Parramatta Road Concord 2137 HOnlNE 102) 747 1888 $10 · $24.99 $ 3.75 U Telephone (02) 747 2022 IFORORDERSONLY 1$25-$49.99 $ 4.50 ROADFREIGHT ANYWHERE 9 6 FACSIMILE (02) 744 0767 TOLLFREE (008)022888 ~0~R~~~ ~ ~0 INAUST~:J.upto20kgl 111 I[ :; I ; 1 ' , SYDNEY - CITY ' CONCORD VISA HURSTVILLE : s JAYCAF : s JAYCAF : s JAYCAF, t:Lt:C. r " (; : s JAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR :s JAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR : s JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR : s JA~C:A~ §L§C:!~c:iNI C:~JAYC:A~ §L§C:!~c:iNIC:~AYC:A~ GORE HILL 117 York St (02) 267 1614BURANDA QLD Mon-Fri 8.30 - 5.30 Thurs 8.30 pm - Sat 9 - 12 355 Church St (Cnr. Victoria Rd)(02) 683 3377 MELBOURNE-CITY Mon-Fri 9 • 5.30 Thurs 8.30 pm · Sat 9 · 4pm 115 Parramatta Rd (0 2) 745 3o77 SPRINGVALE VIC Mon-Fri 8.30- 5.30 · Sat 9.3o· 12 121 Forest Rd (02) 570 7000Mon-Fri 9. 5.30 Thurs 8.30 pm. Sat 9. 4 ADELA E S.A. 188 Pacific Hwy (Cnr. 8ellevue Ave) (02) 439 4799- Mon-Fri 9- 5.30 Sat 9 - 4pm 144 Logan Rd (07) 393 0777 Mon-Fri 9 _5.30 Thurs 8.30 _Sat 9. 12 Shop 2, 45 A'Beckett St City (03) 663 2030 Mon-Fri 9 - 5.30 Fri 8.30 - Sat 9 - 12 887-889 Springvale Road Mulgrave (03) 547 1022 Nr Cnr. Dandenong Road Mon-Fri 9 - 5.30 Fri 8.30 - Sat 9- 2 ) 190 Wright Street (Cnr Selby Street)(08 231 7355 Mon-Fri 9 • 5.30 Fri 8.30 • Sat 9 · 12 1 ~t: l ELE ELE ~t~ ~t~ ELE ELE ELE ~t) ELE ELE ELE ELE ELE ELE , ELE 31~· ••~g-··1~"' ~ti t lt(; I HUNiGSJAY GSJA YC:Af{ LU:(; I HUNf(;&JAYLAK l:Ll:L I KUNILSJA YCAfl ~l~C mONfCSJAYCAR El ECmONICS El f ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECl RONICSJAYCAR ELECTRONICS ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR El ECTRONICSJAYCAR ELECTRONICSJAYCAR ELE §L~C:~c:J NIC:~ YC:A~ ~L~C! RONICSJAYCAR ELECTRON ICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS ~~~~~~ ~~i Al CAPAClTA Build this 4-digit capacitance meter This attractive 4-digit capacitance meter is designed for the workshop or laboratory. It can measure capacitance from 1pF up to 9999µF in seven ranges with an accuracy of better than ± 1% ± 1 digit. By JOHN CLARKE & GREG SWAIN Capacitance meters are always a very useful addition to any electronics workshop. While it is true that capacitors are marked with their value, it is often difficult to interpret the coding or worse still, the markings are illegible. On other occasions, a capacitance meter can be used to select matched capacitor values which may be necessary in critical filter and timing circuits. Many digital multimeters now feature capacitance measuring ranges as standard but these are not usually very accurate. They are also usually unable to measure 30 SILICON CHIP values below about 10pF and above 20µF. The SILICON CHIP Digital Capacitance Meter has no such problems. It is a 4-digit · mainspowered instrument which matches our 1GHz Frequency Meter in styling. It is housed in a grey plastic instrument case and features a red plastic front panel, through which four LED displays can be seen. To use the instrument, you simply connect the capacitor to the test leads and select the appropriate range. The value is then read directly from the big, bright LED display. Seven ranges are available and these allow the unit to measure capacitors anywhere from lpF to 9999µF. An over-range LED flashes whenever the capacitance value is too large for the range selected. Range switching is via two frontpanel switches. One switch sets the capacitance units to pF, nF or µF while the second switch sets the position of the decimal point. Thus, the readings available are 99.99, 999.9 and 9999 for the µF and nF ranges. The pF range operates on the 9999 setting only. The pF range also includes a nulling control. This allows the stray capacitance of the instrument and the test leads to be nulled before taking a reading. The null control is switched out on the nF and µF ranges because it's not needed there. The test capacitor is connected into circuit via two alligator clip leads attached to a BNC line plug. This plugs into a matching BNC socket on the front panel. You can use longer clip leads that those shown in the photos if you wish, provided their stray capacitance doesn't exceed the range of the null control. How it works Let's now see how the unit works. The operating principle is really very simple and relies on the time taken for the test capacitor to charge to a particular voltage. During this time, a 4-digit counter is clocked by a train of pulses derived from a reference oscillator. By suitably adjusting the reference oscillator, the cmmt can be made to equal the value of the capacitor. Fig.1 shows the basic scheme for the Digital Capacitance Meter. In addition to the reference oscillator and 4-digit counter already mentioned, it also uses a gating oscillator and a nulling oscillator. In operation, the gating oscillator generates a positive-going output pulse, the length of which depends on the value of the test capacitor Cx. The larger the value of Cx, the longer the output pulse. This pulse is applied to one input of NAND gate ICBb and gates the signal from the nulling oscillator. The nulling oscillator generates a short negative-going pulse as shown in Fig. l(b). VRl determines the width of this pulse and is the null Most of the parts (including the range switches) are mounted on two PC boards which are then soldered together at rightangles. Note that a small heatsink must be fitted to 3-terminal regulator REG2. control. Fig.l(c) shows the result of gating the two oscillator waveforms with IC8b and inverting the output with IC8c. In effect, the nulling circuit shortens the length of the gating signal by the width of the negativegoing pulse. The length of the pulse from ICBc thus depends on two factors: the value of the test capacitor (Cx) and the width of the pulse from the nulling oscillator as set by the null control. GATING OSCILLATOR IC2, ICBd , IC7b The output pulse from IC8c is applied to one input of IC8a and gates through a train of high frequency pulses from the reference oscillator. These pulses are as shown in Fig.l(e) and clock a 4-digit counter. This counter drives the LED display to indicate the capacitor value. There's nothing especially fancy about any of the parts. In all, there are 9 CMOS ICs, 9 transistors and two 5V 3-terminal regulators, plus associated bits and pieces. A kit of 4-DIGIT LED DISPLAY 4-DtGIT COUNTER CK IC3 HULLING OSCILLATOR IC1 REFERENCE OSCILLATOR IC4 .,. (a) PULSE FROM GATING OSCILLATOR (b) PULSE FROM NULLING OSCILLATOR _J 7_J (c) PULSE FROM ICBc _ ____, (d) PULSES FROM IC8a Fig.1: block diagram of the Digital Capacitance Meter. The time taken for test capacitor Cx to charge determines the width of the pulse from the gating oscillator (a). This pulse is then shortened by the length of the pulse from the nulling oscillator (b) using ICBb & ICBc. The resulting gating signal (c) is then applied to one input of IC8a and gates through high frequency pulses from a reference oscillator to clock a 4-digit counter. MAY1990 31 A IC1, PIN 3 I ~.~,~ I -----,(h IC2, ~N 3 ~..--,--) ·~:.JI_j__ E . ,1) I Cx IC2, PIN 6 I I NULLING PERIOD I---', ICBC, ~IN 10 _ _ I --uu------------------ !'-BEGIN COUNT CK IC3~ PIN 1 2 i l 1 U I I - '--END COUNT H LE IC3, PIN 5 _....:._._ _ _ _ _ _ _ ____, I R IC3, PIN 13 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __, J CE IC6, PIN 13 Fig.2: this diagram shows the waveforms at various parts of the circuit and should be followed in conjunction with the text. Note the latch enable (H) and reset (I) pulses which appear at the end of the count. parts will probably cost you somewhere around the $120 mark. Circuit details Refer now to Fig.3 which shows all the circuit details. The first thing to note is that all the circuit elements shown in Fig.1 can be directly related to Fig.2. IC1 is the nulling oscillator, IC2 the gating oscillator, IC4 the reference oscillator and IC3 the 4-digit counter. The nulling oscillator consists of a 7555 timer, IC1, wired in astable mode. When S1b selects either the pF or nF ranges, the 0. lµF timing capacitor on pins 6 & 2 charges via a 10MO resistor. VR1, the null control, provides the discharge path for the timing capacitor. These timing components give a charging time of about 0.7 seconds (pin 3 high) and a discharge time between O and 35µs, depending on the setting of VR1 (pin 3 low). Thus, IC1 generates a brief negativegoing pulse at its pin 3 output every 0.7 seconds. This output signal (waveform A in Fig.2) is applied to pin 5 of NAND gate ICBb via a 10k0 resistor (pF range only). When the µF range is selected, 32 SILICON CHIP the nulling oscillator works in a different way. On this range, Slb switches a 33µF capacitor and 1MO resistor in parallel with the existing timing components on IC1. This increases the output high time of IC1 to approximately 22 seconds. This is necessary to ensure that large value test capacitors in the µF range have sufficient time to charge. The update time on the µF range is not fixed at 22 seconds, however. That only applies to very large value test capacitors (ie, those approaching 10,000µF). For lower values, the update times are considerably shortened by employing some clever circuit techniques as we shall see later on. As well as feeding pin 5 of IC8b, the pin 3 output of IC1 is also differentiated using an 820pF capacitor and a 4.7k0 resistor. The resultant negative-going spike (waveform B, Fig,3) is applied to the pin 2 trigger input of 7555 timer IC2 and to pin 3 (CK) of D-type flipflop IC7b. This triggers IC2 on its negative-going (leading) edge and clocks IC7b on its positive-going (or trailing) edge. IC2 is wired for monostable operation (triggered by IC1) and the test capacitor (Cx) is charged (and discharged) via a timing resistor selected by Sla and either S2a, S2b or S2c. If the switches are in the positions shown on Fig.3, Cx will charge and discharge via a 1MO resistor [as selected by Sla & S2a). The 100k0 resistor in series with pin 6 of IC2 protects the 7555 if a test capacitor that has been charged to a high voltage is inadvertently connected to the circuit. Otherwise though, the 100k0 resistor plays no part in the circuit operation. IC2's pin 3 output drives six inverters from a 4049 IC package (IC9). These inverters are paralleled in two groups of three and drive complementary transistor pair Qt & Q2 via 6.8k!1 base current limiting resistors. Now let's consider what happens when we connect a test capacitor across the Cx test terminals. Initially, pin 3 of IC2 is low and so pins 2, 4 & 6 of IC9 are all high. Thus, Q2 is on and this effectively grounds the wipers of S2a-S2c. When a trigger pulse arrives from IC1, IC2 triggers on the negative-going edge and switches its pin 3 output high (waveform C). This turns Q2 off and Qt on and so Cx now charges from the + 5V rail via Q1 and the selected timing resistor. The high on pin 3 of IC2 also drives the output of NAND gate IC8d low and this pulls the Set input (pin 6) of dual-D flipflop IC7b low. IC7b then triggers on the trailing edge of the trigger pulse and switches its Qbar output (pin 2) high. This is shown as waveform D on Fig.3 and is the gating pulse which is applied to pin 6 of IC8b. Pin 3 of IC2 remains high until Cx has charged to 2/3Vcc (ie, to 2/3 the + 5V supply rail). At this point, pin 3 goes low and IC8d pulls the Set input of IC7b high. This switches pin Fig,3: all the parts depicted in Fig,l ► can be directly related to the main circuit, ICl is the nulling oscillator, IC2 the gating oscillator and IC4 the · reference oscillator. IC3 is the 4-digit counter and this drives four common cathode LED displays via switching transistors Q4-Q7. Over-range indication is provided by Q3, IC7a and LED 1. S2b S2c DP2 +5V DP2 0.1! 1M 1% 10k 1¾ +5V 100!:l D1 1N4002 D3 1N4002 1% pF S1a IC 2 7555 100k 0.1! 1M 4.7k ex 10M uF S1b 33 .J.:" 16VWl 3 A nFO pF 0.1 O.li i 820pF IC1 7555 STYRO .,. 1.,. +5V 10k +5V D nF F p uF '°'-__ S1d +5v__J' " 12,CK .,. pF 3.15 +5V 7x47!:l a c~17 0.1! RBLLJ' _!_§_ 13 950kHz ~ 11cK1 10 EN 1 EN2 CK2 IC5 4518 IC4 7555 .,. ~ ,-.. co co - ':" E--:i., N "-l "-l IC6 4017 2155 r IC3 74C926 1~ g•4 R 24 H 5LE Al .,. vcc 81 18 DISPLAY 3 BELOW 10 Cl)_M IDP2 3,8 COM IDP3 3,8 15 7 8 D,11 1 . r·· , vcc - - I DIGITAL CAPACITANCE METER DP2 ~ DP3 DISPLAY 4 I I I I cil! ELJc VIEWED FROM 1,cuu,_ .,. ,-, ,-, ,-, DISPLAY 2 I I /c It 131R 8 G:) 1 16VWI •/ d 1~ GND 05 .,. 0 9 .5kHz 14,CK J_! 5 v---;)l~:fsv1sv~\:!J~f,---. __ 1r-+1rr----------..!!lll 1000 .J.:" 22 .J.:" :::::mo-'-:[ 2x1N4002. 16VWI ---•wI ...~... 22 p!UT f + 5V 16VWr A---0 " S3 CE 041 ) ·-~~ 100pFI STYRO ~ JlJ R2 15 Al POWER •• 2 1§_ 04/14 1/-:)b d'l 0.1! 95kHz .,. 4xHDSP-5303 DISPLAY 1 bl16 1J3w.J.: LEDl DYER-RANGE 03 BC548 cotl4 vcc vcc c_gr,, 3,8 PARTS LIST 1 plastic instrument case, 203 x 67 x 158mm 1 PCB, code SC04106901, 173 x 82mm 1 PCB, code SC04106902, 174 x 62mm 1 Scotchcal front panel, 1 95 x 32mm 1 masking film, 195 x 64mm 1 red Perspex sheet, 1 95 x 64 1 aluminium plate, 178 x 45mm x 1.5mm 1 2155 1 A 15V centre-tapped transformer 1 mains cord and plug 1 cord grip grommet 1 plastic push on/push off mains switch (Jaycar Cat. SP-0716 or equivalent) . Note: don't substitute a metal-bodied type . 1 T0-220 heatsink, 27 x 25 x 34mm 2 4-pole 3-position rotary switches 1 5000 linear potentiometer 1 5k0 miniature vertical trimpot 2 20mm knobs 1 15mm knob 1 BNC panel socket 1 BNC line plug 1 red alligator clip 1 black alligator clip 40 Molex pins 1 1 -metre length of 1mm tinned copper wire 1 200mm-length of blue mains wire 2 of IC7b low again to end the gating pulse. Cx now discharges via Q2 and its selected timing resistor in the case of the pF and nF ranges, and via Q2 and either Dl, D2 or D3 on the µF range. These discharge diodes are necessary on the µF range to ensure that the test capacitor discharges completely before the next trigger pulse arrives from ICl. So why have we used the Q-bar output of IC7b as the gating signal instead of the pin 3 output of IC2? After all, the two waveforms are almost identical, the only difference being that Q-bar of IC7b goes high just after pin 3 of IC2 goes high. The reason is that if no test capacitor is connected to the circuit, pin 3 of IC2 generates a brief 34 SILICON CHIP 1 240mm-length of blue heavy duty hookup wire 1 1 20mm-length of brown heavy duty hookup wire 1 50mm-length of red heavy duty hookup wire 1 50mm-length of black heavy duty hookup wire 1 200mm-length of light duty hookup wire (for VR1) 1 80mm-length of 1 2mm heatshrink tubing 7 PC stakes Semiconductors 4 HDSP-5303 12.5mm common cathode red LED displays 1 rectangular red LED (LED 1) 3 7 555 CMOS timers (IC1 ,IC2,IC4) 1 7 4C926 4-digit decade counter (IC3) 1 451 8 dual BCD counter (IC5) 1 4017 decade divider (IC6) 1 4013 dual-D flipflop (IC?) 1 4011 quad NANO gate (IC8) 1 4049 hex inverting buffer (IC9) 3 BC328 PNP transistors (Q1,Q8,Q9) 5 BC338 NPN transistors (Q2,Q4-Q7) 1 BC548 NPN transistor (03) 5 1 N4002 1 A diodes (D1 ·D3,D5,D6) 1 1 N914 diode (D4) pulse each time it receives a trigger signal from ICl. Without IC7b, this pulse would gate through pulses from the reference oscillator to the counter and so the display would indicate a reading when it should be displaying 0000. Because of the way it is clocked, IC7b doesn't respond to these short pulses from IC2 and its Q-bar output remains low. Thus, no pulses can be gated through to the counter and so the display reads 0000 with no capacitor connected - which is just what we want. On the pF range, IC8b & IC8c gate the signals from ICl and IC7b as described previously for Fig.1. This produces waveform F on pin 2 of ICBa which then gates through the pulses from the precision 2 7805 5V 3-terminal regulators (REG1, REG2) Capacitors 1 1 OOOµF 16VW PC electrolytic 1 33µF 1 6VW PC electrolytic 1 22µF 16VW PC electrolytic 1 1OµF 16VW RBLL electrolytic 1 1OµF 1 6VW PC electrolytic 1 4. 7µF 16VW PC electrolytic 1 1µF 1 6VW PC electrolytic 8 0. 1µF monolithic 1 0.1 µF 1 % polyester (for calibration) 1 820pF polystyrene 1 1 OOpF polystyrene Resistors (0.25W, 1 10MO 2 1 MO 1 % 1 1MO 1 1 OOkO 1 % 2 1 OOkO 2 10k0 1 % 3 10k0 2 6.8k0 5%) 1 4. 7k0 1 2.2k0 1 1 kO 1 % 1 1 kO 1 6800 1 1000 1 % 1 1000 9 470 Miscellaneous Solder, machine screws and nuts, self-tapping screws. Note: this circuit will only operate correctly with CMOS 555 timer ICs. These can be marked ICM7555, TLC555CN or LMC555CN. The LM555CN in not suitable since it is only a standard 555. oscillator circuit to the 4~digit counter (IC3}. When the nF and µF ranges are selected, the nulling circuit (but not !Cl} is disabled by using Sld to switch pin 5 of IC8b to + 5V. This means that IC8b now gates through the entire waveform from IC7b (ie, IC7b's output is no longer shortened by the width of the pulse from the nulling oscillator). Reference oscillator Reference oscillator IC4 consists of yet another a 7555 timer. This is wired in astable mode and oscillates at 950kHz as set by a lkO resistor, calibration trimpot VR2 and a l00pF timing capacitor. The 950kHz signal appears at pin 3 and is applied to the pF range of Slc The four LED displays are mounted using Molex pins. Install each display with the decimal point at bottom right. Mount the over-range indicator LED so that its top surface is level with the displays. and also to the CKl [clock) input of IC5. IC5 is a dual BCD counter which divides the 950kHz output from IC4 by 10 and 100. The divide-by-10 signal (95kHz) appears at the Q4 1 output [pin 6) and is applied to the nF position of Slc. It also clocks the CK2 input (pin 9) of the second counter to produce the divideby-100 (9.5kHz) signal at Q4 2 (pin 14). This 9.5kHz signal is fed to the µF position of Slc and also clocks decade counter IC6 [4017). Depending upon the range selected, S 1c couples one of the reference signals (950kHz, 95kHz or 9.5kHz) to the pin 1 input of IC8a. When the gating signal from ICBc is high, the selected reference signal [waveform G) passes through ICBa and clocks IC3, a 74C926 4-digit counter. In addition to the 4-digit counter, IC3 also contains latches, BCD to 7-segment decoder drivers, and internal multiplexing circuitry. It drives four common-cathode displays in conjunction with transistors Q4-Q7. The a-g display segments are driven via 470 current limiting resistors. S2d, Q8 and Q9 provide the decimal point switching. When S2d is in the open position (as shown on Fig.2), both transistors are off and so the decimal points are also off. When DP3 is selected, Q9's base is pulled low via a 1okn resistor and so the transistor turns on and lights DP3. Similarly, when DP2 is selected, QB turns on and lights DP2. Strictly speaking, QB & Q9 can be eliminated and S2d used to switch the decimal points directly to the + 5V rail via 470 current limiting resistors. However, this arrangement would have upset the stability of the meter because we would have had to route the high-current decimal point supply lines close to the Cx input. QB & Q9 solve this problem because they require only low current lines for their bases to pass near the Cx terminals. Latch enable & reset In order to function correctly, the 74C926 must be fed with two control signals: latch enable (LE) and reset (R). The LE signal instructs the 74C926 to transfer the contents of the counters to the latches. The latches then drive the display, leaving the counters free to be reset and clocked with the next series of pulses. The latch enable and reset signals are generated using a 4017 decade counter [IC6) with decoded outputs. This device is clocked by the 9.5kHz output at pin 14 of IC5 and each decoded output goes high in turn for the period of the clock signal. The decoded "2" output (pin 4) provides the latch enable signal while the decoded '' 4'' output [pin 10) provides the reset signal. These are shown as waveforms H I on Fig.3. Thus, the sequence of events is as follows. First, the gating signal arrives at pin 2 of IC8a and the reference oscillator [or one of its divided outputs) clocks IC3. Next, after the gating signal has finished, the latch enable is taken high by IC6 and the contents of the counters are latched and displayed. Finally, the reset (pin 13) is pulled high and the counters are cleared for the cycle. Note that the Reset input (pin 15) of IC6 is connected to pin 3 of IC2. This means that IC6 can only be clocked when pin 3 of IC2 is low (ie, at the end of the gating period). This ensures that the latch enable and reset signals for IC3 are generated at the appropriate times. IC6 also provides the rapid update feature for low value capacitors on the µF range. It works like this. At the end of the reset pulse, IC6's decoded "5" output (pin 1) goes high and pulls the Clock Enable [pin 13) high. This stops the counter and so decoded output "5" remains high [waveform J on Fig.2). This high now quickly charges the 33µ,F timing capacitor on Slb via a 1ookn resistor and D4 and thus enables ICl to deliver a new trigger pulse to begin the next cycle. Without this feature, the µF range would only be updated every 20 seconds or so, since it would & MAY 1990 35 Fig.4: here's how to install the parts on the two PCBs. Note that you will have to remove two pins from Sl before soldering it to the display board. Be sure to use 1 % resistors where indicated and take care with component polarity. , -I ~ I•• •7 I I 0 --ob-. ~ or. Ok OOk 1M 100n / D3~ / -aDot take this long for the 33µF capacitor to charge via the lMQ resistor. By using IC6's decoded "5" output to charge the 33µF capacitor, the display update time is reduced to slightly longer than the charging time for the test capacitor (Cx). Over-range indication Q3, flipflop IC7a and LED 1 form the over-range indicator circuit. This is driven by the carry out [CO) output of IC3. During each cycle, the CO output goes high when [and if) a count of 6000 is reached and this turns on Q3 which pulls the clock input [pin 11) of IC7a low. If IC3 is subsequently clocked from 9999 to 0000, its CO output goes low again and Q3 turns off. When this happens, the CK input of IC7a is immediately pulled high [via the 2.ZkO resistor) and clocks a high to the Q output which lights LED 1. IC7a is then reset using the same pulse that resets IC3 and so the Q output goes low again and the LED goes out. Thus, LED 1 flashes on and off 36 SILICON CHIP for counts greater than 9999 to indicate that the meter should be switched to the next highest range. Power supply Power for the circuit is derived from a 15V centre tapped lA mains transformer. This feeds a full-wave rectifier circuit consisting of D5 & D6 and the resulting unregulated supply rail then used to drive two + 5V 3-terminal regulators. One of these regulators supplies power to IC3 [Vee) and the displays, while the other supplies + 5V to the rest of the circuitry. So why use two separate regulators? The reason is that IC3 and the displays generate hash on the supply line because the displays are multiplexed. By using two separate regulators, this hash is kept out of the sensitive capacitance measuring sections of the circuit. Building it Despite the circuit complexity, the Digital Capacitance Meter is easy to build. All the parts are mounted on two PC boards which are soldered together at rightangles and mounted in a standard plastic instrument case. This method of construction reduces the internal wiring to a minimum. Most of the parts are mounted on the main PCB (code SC04106901), while the display PCB (code SC04106902) carries the LED displays and range switches. The completed assembly slots into a matching groove in the front of the case, along with the captive red Perspex panel which is held by the switch locking nuts. Four self-tapping screws are then use to secure the assembly to integral pillars in the bottom of the case. A self-adhesive dress label covers the bottom half of the Perspex panel and this gives the unit a very professional appearance. In addition, a light mask is fitted to the back of the panel to blank out unwanted areas of the display board. Fig.4 shows where the parts go on the two PC boards. Begin by installing the wire links on the main Fig.5: here's how everything goes together inside the case. The power transformer is mounted on an aluminium plate and this is secured to the bottom of the case by selftapping screws. The Perspex front panel is mounted on the rotary switches and secured by the locking nuts. REAR PANEL ALUMINIUM PLATE ACTIVE (BROWN) 8 <at>I :::,..,,::._~----~~__r-- 8 -= ' ~ ~~ ~ ~ r SELF·TAPPING_/ SCREWS :>......=..____ ----r1 SO[rLDER REGULATOR HEATSINK I I PLASTIC I INS ULA TING ----i SLEEVING I I : S1 PCB (0.6mm tinned copper wire will do nicely), then install PC stakes to terminate the leads from the power transformer secondary and from VR1. This done, you can install the remaining parts on the main board but make sure that all polarised parts are correctly oriented. These parts include the ICs, transistors, regulators, diodes and electrolytic capacitors. Make sure that the correct transistor type is used at each location. VR1 to be positioned as close to the centre of the PC board as its mounting slot will allow so that it clears one of the side pillars in the case. No heatsink is required for REG 1 which can be bolted directly to the board. Display PCB Now for the display PCB. Install S2 PC pins at the Cx and GND terminals, then install the wire links, diodes, resistors, transistors and capacitors. The over-range LED should be installed so that its top surface is 13mm above the surface of the board. Don't trim the LED leads just yet in case you have to make adjustments later on. Note that the lOOk!J resistor on pin 6 of ICZ is stood on end to save space. For the same reason, the O.lµF capacitors should all be miniature monolithic types (don't use greencaps - they won't fit on the board). A small heatsink is fitted. to 3-terminal regulator REGZ to aid heat dissipation. Smear the metal tab of the regulator with heatsink compound and install a solder lug under the head of the screw before bolting the assembly to the PC board. Note that the heatsin.k needs The plastic insulating sleeving fitted over the power switch should be long enough to pass right through the heatsink. In addition, the heatsink is earthed by connecting it to mains earth (see Fig.5). M AY 1990 37 solder tack them in a couple of places. Now test the assembly in the case (the PCB goes in the rearmost slot at the front of the case) and make any adjustments that may be necessary. When everything is correct, solder all the matching pads together to create a permanent assembly. Note that is is normal for the main PC board to sit slightly proud of the standoffs on the bottom of the case. Final assembly The combined PCB and front panel assembly slides into the slots at the front of the case and is secured by four self-tapping screws through the main board. Take care with the mains wiring. The four 7-segment LED displays are stood off the board using Molex pins. To do this, separate the Molex strips into eight 5-pin lengths, then solder them to the board and snap off the shorting bars. The displays can now be pushed into the pins as far as they will go. Check that the decimal point is at the bottom right of each display. If you do insert a display upside down, all sorts of odd segments will light up. The two rotary switches can now be installed on the PCB. Use a pair of sidecutters to remove two pins from Sl as indicated on Fig.4 and push both switches down onto the PCB as far as they will go before soldering the terminals. The board will accept both the open-style rotary switches sold by Dick Smith Electronics and the enclosed type sold by other retailers. Construction of the PCB assembly can now be completed by soldering the two boards together at right angles. To do this, carefully align the edge pads of the two boards and The input connector consists of two alligator clip leads wired to a BNC plug. You can make the leads longer than those shown here if you wish, provided their stray capacitance doesn't exceed the range of the null control. 38 SILICON CHIP Fig.5 shows the final assembly details. Begin by affixing the adhesive label to the bottom of the Perspex panel, then position the light mask on the back of the panel and mount the mains switch, nulling potentiometer and BNC input socket. The front panel can now be mounted on the two rotary switches and secured with the switch locking nuts. If the Perspex panel is not sup. plied pre-drilled, use the light mask to mark out the positions of the mounting holes. The power transformer is mounted on a 178 x 45mm aluminium panel at the rear of the case. Use screws, nuts and lockwashers to secure the transformer and earth solder lugs as shown in Fig.5. This assembly is secured to integral standoffs in the bottom of the case using self-tapping screws. The mains cord enters through a hole in the rear panel and is clamped using a cord grip grommet. Before clamping the cord, strip back about 15cm of the outer sheath so that the active (brown) lead can reach the mains switch. The mains wiring can now be completed as shown in Fig.5. Note the earth link between the solder lug attached to REG2 and the earth lug on the transformer mounting panel. This is necessary because the leads to the mains switch pass close to the heatsink. As an additional safety precaution, sleeve the switch terminals and the leads adjacent to the he~tsink with heatshrink tubing (see photo). The construction can now be completed by wiring up the transformer secondary, the null control and the BNC input socket. «H Mllm -t11n1a1.u1;1., L:sco41os902 0 ~T"" 0 0) o:::t 0 (.) (/') 'ID Fig.6: here are full-size artworks for the two PC boards. Keep the leads between the BNC socket and the display board short and make sure that the centre pin of the socket goes to the Cx pin. The GND pin connects to the solder lug on the BNC socket. The leads between the main board and the null control are routed through a hole near the top of the display board. Now go over your work carefully and check for possible wiring errors. In particular, check for missed solder joints, shorts between adjacent pads on the PCBs, and incorrectly oriented parts. If everything is OK, switch on and check that all four digits show a reading. This should be 0000 when S1 is in either the µF or nF position. Check that the correct decimal point appears when S2 is set to 99.99 and 999.9. Now rotate the null control fully anticlockwise and select the pF range. Check that you can zero the reading by winding the null control in a clockwise direction. If you strike problems, switch off immediately and check for wiring errors. The waveforms shown in Fig.2 will be useful for troubleshooting if you have access to a CRO. Calibration A 0. lµF 1 % calibration capacitor has been specified in the parts list but other precision values could 11\ also be used if you have them on hand. To calibrate the instrument, connect the 0. lµF capacitor to the test terminals and select the nF and 999.9 ranges. Now adjust trimpot VRZ until the display reads 100.0 (ie, l00nF) - and that's it. You don't have to calibrate the other ranges. Once the unit has been calibrated on one range, the other ranges will automatically be correct. Using the meter Note that some care should be exercised when nulling the instrument on the pF range. The correct procedure is to wind the null conMAY 1990 39 t,() = = 1: "C CII "'CII "C Ql "' = Ql ~ = CII I.I ..:.: "'CII e -! = ~ ..;,,l a: w 1w "'CII e ~ ... w (1) 0 (/) (.) .D ·= <( 0 ... :: (1) ~ea ... E u Ill -(/) c. Ill QI u (1) (1) c,; (0 0 .1:.- ~!: 'C C> • • C: C>;; ·= gC: 3:: u C: ... Ill C: 0 z - 1( .) <( a. <( (.) ..J <( - 1- C, 0 a:w c., ..,._wz > <C a: Oa: w ~ trol fully anticlockwise, then wind it slowly back until the display just reaches 0000. Once the display shows 0000, you've found the correct nulling point and the null control should not 40 SILICON CHIP be moved. If you do keep winding the control back, the display will still read 0000 but the nulling pulse will now be too long and readings on the pF range will be too low. Finally, be aware that a capac- itor charged to a high voltage and then connected to the test terminals may damage the circuit. It is therefore a good idea to ensure that the test capacitor is discharged before connecting it to the meter.I§;! ' II ROBBER STOPPERS" I " ' OR Features include: • 15 x 15m coverage, 105 degree angle. * Full SMD Technology • Fully Computerised Quality Control system • Low noise, high sensitivity twin element pyroelectric • Extra High RF immunity • Very compact, low profile • Silent relay • Flat wall & corner mounting Famous IEI brand 4 sector alarm Panel. Designed and manufactured in Australia for the Alarm Industry. One of the most popular Alarm Panels on the market! Features Include: • Adjustable entry delay• Exit delay of 90 seconds • Automatic test mode • Can select 'Home' or 'Away' modes• 24 Hour Panic status• 24 Hour Tamper circuit • Built-in power supply and 1.9 Amp back-up battery • Welded steel cabinet plus MANY OTHER FEATURES! WAS $349 WAS $119.00 3 NOW S69.95 NOW s279 s L Features include: • EEPROM • Local siren test • Keypad programmable • Two year warranty • Watch-dog timer circuit • Auto test facility • Built-in siren driver • Partial (arming) facility • 4 Wire keypad • 8 E.O.L. supervised zones • 15 User codes • Up to 4 Remote keypads • One button arming Probably the most advanced Panel of it's type. This Panel is fully programmable by the user and can be programmed to suit the requirements of any situation. Includes : Remote Keypad, 12V 6.5Ah Rechargeable battery + power supply ~ ~ L. 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FLUSH REEDS .......... $7.95 ,20 d812 PIEZO H H i'j ,l r-. , HORN COVER & TAMPER SWITCH .............. .... .$24.95 ;.;.::aatito.er.4~:.v.~$a❖#.nd.•.•~•t❖#MttJ.•.•at-Q:.:wt4pp.&;. . •· •.•.•·• . . • · •·; :·. · •: . . . . ·. • · · ·.·;.; .;.;.;.; .:.:.; . . . :. . . :.::··:·:·:❖•❖ •••·.·.·.·• ••::.:.;•••:.;.:.;••••• CHRISTIE$ BEACH 203 Wright St. 24 Beach Rd. Ph:(08)212 5505 382 3366 ENFIELD .I LONSDALE ~ - - - - - - - - - - - ~ 5 Somerset Circ. 445 Main Nth. 349 6340 ADELAIDE BRIGHTON FINDON 500a Brighton Rd. 127 Findon Rd. 377 0512 347 1188 MAIL & PHONE ORDERS Rd. Delivery charge of $8.00 for packages up to 10kg by mail or up-to 3Kg by overnight Air-bag . Min. order $10 AMATEUR RADIO By GARRY CRATT, VK2YBX Use this electronic load to check power supply performance Most amateurs use high-wattage resistors for checking out power supplies but that's often inconvenient. This electronic load can be used with power supplies of up to 30V output and is easily adjusted to give the required load current. When it comes to checking the performance of power supplies and batteries, one of the most useful pieces of test equipment is the resistive load. By using such a device, the performance of current limiting circuitry, battery capacity, power supply ripple and terminal voltage under load can all be checked. Unfortunately, due to the infinite number of voltage and current combinations that may require testing, the user is likely to end up with a mass of high wattage resistors wired in series or parallel. During testing, these may become quite hot and the whole arrangement can become unmanageable. This article describes the con- The electronic load is built into a standard metal box and this is fitted with large finned heatsinks for the power transistors. A multiturn pot on the front panel allows precise adjustment of the load current. 42 SILICON CHIP struction of an "electronic" load which can operate at any voltage up to about 30 volts, is capable of dissipating up to 10 amps, and is adjustable. In addition, the electronic load has provision to monitor terminal voltage under load using a standard multimeter. A digital multimeter is ideally suited for this application, although a plotter could also be used to monitor terminal voltage under load over a prescribed time interval. How it works Fig.1 shows the circuit details of the electronic load. Basically, it uses two transistors (Ql & QZ) which are wired as emitter followers, each driving a 0.470 resistive load. This resistive load consists of seven paralleled 3.30 5W resistors. In effect, the circuit is a large adjustable current "sink". We can use it to vary the amount of current pulled from a power supply. The bias to both transistors is controlled by multiturn potentiometer VR 1. This functions as the "load" control and allows the current dissipated in the emitter load resistors of each transistor to be varied as required. Thus, you can set the load to draw a specific current, which is monitored by the 10A ammeter on the front panel of the unit. This is a most useful feature, as the unit can be used to check a variety of power supplies, batteries and even solar cells under various load conditions. The 3.30 resistors have .been 10A d VIEWED FROM BELOW + 02 2N3055 VOLTAGE TEST Fig.t: the circuit uses two power transistors (Qt & Q2) which are wired as emitter follows, each driving a 0.470 resistive load. VRt varies the bias on both transistors so that the circuit behaves as an adjustable current sink. ELECTRONIC LOAD chosen to limit the maximum load current and to ensure that the two transistors are protected against thermal runaway. These resistors could be decreased in value to allow the load to handle more current but you would have to use larger heatsinks for the transistors than those shown in the photos. Construction Our unit was built into a standard metal project box with air vents to allow cooling of the 14 5W emitter resistors. Ventilation is of prime importance for this project and must be taken into account if you intend substituting for the case specified in the parts list. Fig.2 shows the wiring details. The 14 3.30 5W resistors are all mounted on a PC board coded SC 14106901 while the four smaller resistors are mounted on a second PC board coded SC 14106902. Note that 6 of the 5W resistors are "stacked" above other resistors on the board. Leave a few millimetres of space beneath the 5W resistors so that the air can circulate freely for cooling. The two transistors are mounted on heatsinks which in turn are .mounted on either side of the metal case. This external mounting allows adequate ventilation for the transistors. Both transistors must be electrically isolated from the heatsinks using mica washers and insulating bushes. Fig.3 shows the details. Smear heatsink compound on all mating surfaces before screwing the transistors down, then use your multimeter (switched to a high E------- 01 B C ~ V (O+ VOLTAGE TEST + METER Fig.2: use heavy duty cable to wire up the circuit and note that some of the 5W resistors are stacked one above the other. Take care with the connections to Qt & Q2. ohms range) to confirm that the transistors are correctly isolated from the heatsinks. Heavy-duty wiring leads can then be soldered to the emitter and base pins, while the collector connections can be made via solder lugs secured by the mounting screws. MAY1990 43 PARTS LIST 1 metal case, 150 x 76 x 134mm (Jaycar HB-5444 or DSE H-2743) 2 heatsinks (DSE H-37 40 or Jaycar HH-8560) 1 PC board , code SC14106901, 127 x 50mm 1 PC board, code SC14106902, 25 x 25mm 1 1OA panel meter 2 binding post terminals ( 1 red, 1 black) 2 banana sockets (1 red, 1 black) 1 5k0 multiturn pot (Geoff Wood) 1 vernier dial to suit pot (Geoff Wood Electronics) 2 2N3055 NPN transistors (Q1,Q2) 2 T03 mounting kits (mica washers plus insulating bushes) 2 T03 insulating caps 2 4700 ½W resistors 2 1 000 ½ W resistors 14 3.30 5W resistors 3 6mm-long threaded spacers 6 screws to suit spacers The prototype was built up on Verohoard hut the PCB version will he easier to build. The heatsinks are secured to the lid using self-tapping screws and the leads to the transistors run through the ventilation slots. The self-tapping screws used to secure the lid of the metal box were also used to secure the heatsinks. To do this, you will have to mark and drill the appropriate holes in the heatsink flanges. This done, mount the heatsinks in position, then drill additional holes through the lid at the top of each flange (two for each heatsink) to accept additional self-tapping screws. The case can now be drilled to accept the front panel components. These parts include the meter, the binding post terminals, banana sockets and the 10-turn pot. The meter cutout can be made by drilling a series of smaller holes around the circumference, and then filing the hole to a smooth shape. Both TO-3 transistors should be covered with plastic insulation caps, as the body (collector) of each transistor sits at the same potential TABLE 1 44 SILICON CHIP 0 HEATSINK 0 =--CASELID ~ - 4 - (§-INSULATING BUSH ~-- SOLDER LUG WASHER ,.-:1,,_ <at>--- ~ <at>....-SPRING WASHER <at> <at>--NUT Fig.3: the power transistors are isolated from the heatsinks using T0-3 mounting kits. Smear all mating surfaces with heatsink compound before mounting each transistor, then use your multimeter to confirm that its case is properly isolated from the heatsink. as the power supply or battery under test. A short circuit between either collector and a heatsink, which is at ground potential, would cause maximum current to be drawn and could damage the power supply being tested. We used a vernier coupled to the 10-turn potentiometer to give precise adjustment of the load current, as this control is quite sensitive. If you don't want to go to the trouble of obtaining etched PC boards, use Veroboard instead (as in the prototype). The two circuit boards are mounted inside the case on 10mm tapped spacers. Operation Finally, you must observe a few simple precautions when operating the unit. Because of the heatsinks specified, the maximum power that this unit can dissipate is about 60W Supply Voltage 3V 5V 9V 10V 12V 15V 18V 20V 22V Maximum Load 10A 10A 6.7A 6A 5A 4A 3.3A 3A 2.7A 2.4A 25V 30V 2A Mad It is a good idea to fit plastic insulating caps over the power transistors to prevent accidental shorts to the heatsinks. The heatsinks shown are capable of dissipating about 30W each (ie, 60W total). (or 30W for each transistor). This rating determines the maximum load current that should be drawn at a particular supply voltage. For example, if the supply voltage is 30V, then the maximum current that should be drawn is 2A (ie, P = IV = 30 x 2 = 60W). Similarly, if the supply voltage is 20V, then up to 3A may be drawn. Increasingly higher currents may be drawn at lower voltages, up to a maximum of lOA. Table 1 shows the maximum safe current that can be drawn at each voltage. Do not exceed these cur- Fig.4: you can use these artworks to etch your own PCBs or you can buy commercial boards from the usual retail outlets. rents - you could cause damage to the electronic load if you do. In practice, this all means that when testing a power supply, you should start off with VR1 set to maximum resistance. This equates to minimum load current. After that, VR1 is wound back (anticlockwise) until the load current is at the required value (while keeping in mind the maximum values listed in Table 1). ~ SC 41 in A t a ,a? p Polystryrene Capacitors - 1 0pF to 1mF Voltage Range 63VDCW to 10,000 VDCW Tolerance - 0.25% to 10% Allied Capacitors Australia manufactures capacitors to the specification of the customers using high quality, imported polystyrene and aluminium foil with a tolerance of 1 micron. Our capacitors are manufactured to the system of Total Quality Control. We can provide Just In Time delivery if required, together with a Certificate of Conformance if requested. Specific values between 1 0pF and 1uF are no more expensive than standard value components. You can now design circuits to use a single capacitor rather than a number in parallel or series to achieve a desired value. Personalised labelling is available at no extra cost. Your component code or name can be built into the capacitor. Minimum runs of only 25 allow you to specify a particular value for a prototype run. Delivery lead time for short runs is 3 to 4 working days, and for longer runs is less than 2 weeks . We are also able to produce capacitor styles for applications such as dual mount, end filled and mini style capacitors. Call us now on: (02) 938 4690 ALLIED CAPACITORS AUSTRALIA PO Box 740 Brookvale, NSW 2100 ~===~~s=~~!~c ~~~~··~~~ Disk/Floppy Disk Controllers CAT. LACPP3 3 metre cab!• CAT IC256K10 CAT. LACPP5 5 metre cable 41256-10 CAT. 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In all cases they are guaranteed to perform to an equal or higher standard . .. ,...... 1: 1: .. 1: ... • ~ =~ I I ~ I i I .- 16-Channel g Desk, Pt.4 In this final article on our new 16-Channel Mixing Desk, we present the test procedure for the equaliser/VU boards and the wiring details for the whole mixer. By JOHN CLARKE & LEO SIMPSON As we noted last month, this mixer is a very big unit to assemble and so it is wise to proceed slowly and carefully. By rushing in and assembling all the boards at once, you could make a lot of mistakes and have a lot of work to do to fix them. By far the best procedure is to assemble and test one of each of the boards first, before building the others. So far then, we have given the assembly procedure for all the boards and the test procedure for all of the boards except this last one, the equaliser/VU board. There ,"';""·•,'7:'" ""t> ' ' are four of these and they each carry a master output level control. The effects board is the biggest used in the mixer and it carries the most circuitry. To check it, you will need to refer to the circuit diagram on page 67 of the March 1990 issue and the wiring diagram on page 73 of the April 1990 issue. You will also need to wire a 1okn slider (VR13) to the board. Now connect the + 15V, -15V and 0V power inputs for the equaliser part of the PCB and the + 15V, - 15V, + 5V and 0V for the display section of the PCB. Apply ~"->-!=l~~.'"::' ' This rear panel view shows the mounting locations for the six 6.5mm insulated mono panel sockets and for the four 3-pin XLR male plugs. The 16 XLR 3-pin sockets are mounted to the right of the XLR plugs. 48 SILICON CHIP power and check for + 15V on pin 8 of IC9, IC10, IC11 and IC20, pin 7 of IC13, IC16, IC17, IC18 and IC19, pin 4 of IC12 and IC20, pin 3 of IC14 and IC15, and pins 2 and 14 of IC21. For the - 15V rail, check pin 4 of IC9, IC10, IC11, IC16, IC17, IC18 and IC19, and pin 11 of IC12. Apply a 10mV signal to the channel input (marked CH1/CH3 on the layout diagram) and measure the signal at pin 1 of IC9. It should be 340mV RMS. Theil with the master fader VR13 at maximum setting, a 1.39V RMS signal should be present at pin 7 of IC9b. Wind the slider up and down and observe that the signal can be varied over the full range down to zero. With VR13 at maximum setting, check for a 1.39V signal again at pin 7 of IC10. The operation of the 5-band equaliser is checked by setting your audio oscillator to 60Hz and measuring at pin 7 of IC10. With the 60Hz pot at full clockwise rotation, the signal should be boosted by about 12dB (4 times the signal) to 5.5V. Check that the cut is - 12dB (1/4 the signal) to 350mV at full anticlockwise rotation of the 60Hz pot. In a similar manner, check the 240Hz, lkHz, 3.5kHz and 10kHz equaliser bands. · Now with all equaliser pots recentred and a lkHz signal, check for a 1.39V signal at pins 1 and 7 of IC11. The signal at pin 1 should be inverted with respect to the signal at pin 7. You can check this with an oscilloscope or by connecting your multimeter across pins 2 and 3, the balanced line outputs of the board. The AC reading should be 2.78V RMS; ie, the outputs add. Without adjusting the signal levels, you should also find 1.39V AC present at the monitor output; ie, the headphone output. The effects, equaliser/VU & preamplifier boards are all secured to the front panel via their rotary pots. While you have been doing the above checks with signal present, the level meter should be operating. The bar section of the display should rise with increasing signal level and when the signal is reduced in level via the fader, the peak hold LED should drop back at a slower rate than the average bar signal. The TRIM3 and TRIM4 trimpots can be adjusted by first removing signal by shutting off the fader control. Adjust both TRIM3 and TRIM4 so that the lower LED for the ba'r and dot display just extinguishes. TRIM2 allows the setting of the display to read 0dB for a 1 V RMS signal at the balanced line output. This can be done now. This completes the testing procedure for the boards. Now to repeat what we said before: only one board should be assembled and then tested, for each of the mixer boards. When the tests on these initial boards are complete, then and only then should you assemble the other boards. Otherwise, if you There are 20 slider pots on the front panel & these are all mounted using 15mm spacers, grub screws and black dress screws (see text). assemble all boards first , you may find yourself undoing a lot of mistakes. Now we can proceed to the mechanical assembly of the mixer, starting with the main panel. Front panel assembly Before any wiring can be done, all the hardware has to be assemblMA Y 1990 49 Adjusting the rotary switches Single-core shielded cable is used for the connections between the 6.5mm jack sockets and the two effects hoards, while twin-core shielded cable is used between the 3-pin XLR plugs & the equaliser/VU boards. All 16 rotary switches are specified as 3-pole 3-position types. What you will be supplied with is 4-pole 3-position types which can be adjusted to give only three positions. To do this, you just remove the switch mounting nut and lift off the washer/stop. You then put it back so that the stop lug is back one setting. Screw the mounting nut back and rotate the switch shaft to check that the switch now has three operating positions. Install each rotary switch using a lockwasher underneath the securing nut. Orient the switch so that when set to the middle position, the flat of the shaft is parallel to the side of the panel and on the left hand side. The switch knobs (grey insert} can then be fitted. Mounting the slider pots This interior view shows most of the 16 identical preamplifier boards while Fig.6 in the April issue shows the wiring details. Install the leads in the order shown in the wiring table. ed onto the mixer panel. At all times you need to be careful not to scratch the finish of the panel. We suggest you lay an old towel or blanket over your workbench or table while this task is in progress. Before the printed boards are mounted, all the switches, sockets and slider pots need to be installed. As with the pots, the shafts of the 50 SILICON CHIP rotary switches need to be cut to 10mm in length. They can be cut with a hacksaw and cleaned up with a file so that the knobs go on easily. While you are working on these switches, nip off the plastic locating pin with a pair of side cutters. This must be done since there are no holes in the mixer panel for the locating pins. Now for the 20 slider pots: these are fitted with 15mm tapped spacers at each end and then mounted on the front panel. Supplied are two spacers, two grub screws and two black dress screws for each slider. The grub screw is screwed halfway into the slider mounting hole and then the tapped spacer is screwed down onto the the grub screw. The slider is then secured to the front panel with the black dress screws, with pins 1 and 2 oriented towards the bottom of the panel. The slider knob can then be fitted. The headphone sockets, in/out switches, 2/4 channel switch and overload LED bezels can now be installed. Note that the 16 toggle switches must be oriented so that the toggle moves sideways to agree with the front panel artwork. The PCBs can now all be installed. To begin with, just secure each board with a washer and nut on the top pot and one on the bottom pot. This is important since some of the boards may have to be removed to correct unforseen faults. For the same reason, do not install the knobs on the pots at this stage. The equaliser PCBs are mounted so that the LED displays fit flush with the surface of the front panel. If necessary, use more WOOD FOR CHIPS .. . WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS .. WOOD FOR CHIPS .. WOOD FOR CHIPS ... WOOD FOR C Tool Box This month we're concentrating on tools. We get a Jot of requests for quality tools from professional . users. Well feast your eyes on this lot! ~ :i: <..J cc C) "Cl C) ~ ~ ::r: <..J cc C) "Cl C) ~ Bonus FREE Weller Pyro-pen With Giant Xcelite Tool Kit this month! The serviceman's dream is here in this huge assortment of Xcelite hand tools. Case is covered in posh tan leather grain vinyl and has removable tool pallets in lid and bottom plus solid brass hardware. Contains Nutdrivers: 8, 10 11 13mm Soldering Iron: 25W plus solder lnterchangeab/11 Screwdri1111rs: Handle, extension, 9 Allen hexsocket blades, 7 Hex-nut blades, 2 slotted screw blades, 2 Phillips blades, reamer Pli11rs etc: Seizer, adjustable wrench, midget slip joint, utility, long nose, needle nose and chain nose pliers, 2 diagonals, electronic snips, wire strippers and electrician's knife. Screwdrivers: 6 slotted, 1 Phillips, 5 piece offset ratchet set 4-Way combination nutdriver 3m measuring tape. Plus FREE Weller Pyro-Pen Gas Iron Case measures 470x343x127mm Mag~:m ~ The remarkable Maggylamp magnifies any object under a clear cool light leaving both hands free for operators engaged in work demanding high deprees of accuracy - like servicing surface mount boards and other delicate IC operations. Standard equipment in labs, repair shop, factories etc. Essential aid to efficiency .. e 127mm bi-convex lens, 4.00dioptres, focal length 254mm. • Flexible arms for easy positioning. • Handsome sturdy construction. • Essentially a microscope with lighting . Value at $250 Individual Tools Coax~ Suits RG58 and RG59 $41.95 $1295 ~ :i:<..J cc C) "- 8 ~ carry case. Ideal for field service use and you'll save over $50 on the cost of individual items D-Sub Crimper Assemble contacrs quickly $88.95 Nibbling Tool Cuts up to 18gauge steel and other hardened metals. Ideal for copper plastic, aluminium etc. Simply dri/i 3/8' hole Ideal for square panel cu t ~· [I] 10 piece screw type. Holes from 16mm to 30mm diameter. 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Kil Description Price ATM0t 3 digit Counter $33 .60 ATM02 4 digit Counter 5D.40 ATM03 31 /2 digit DVM 59.40 ATM04 1Hz Timebase 22.40 ATM05 Fibre Optic Modem 75.00 ATM06 Reciprocal Calculator 29.40 ATM07 10MHz Timebase 45.60 ATM0B V/F Converter 42.60 ATM09 FN converter 42 .60 ATM10 Quad Power Supply 60.60 ATM1110 Minute Controller 46.20 ATM126 dig Batch Counter 75.00 ATM13 3 Digit Counter 65.40 ATM1 4 3 1/2 digit LCD DVM 42.60 ATM16 1OkV Isolator 70.80 ATM17 Storage Adaptor 193.80 ATMIB 8 bit UART 66.00 ATM19 6 dig Up/On Counter 69.60 ATM20 IR Transceiver 39:60 ATM21Multi-Timebase 42.60 ATM221 6Ch Tranmitter 77.40 ATM23 16Ch Receiver 77.40 ATM24 22/3 Com ms PCB 34.80 ATM25 22/3 Radio Modem 66.60 Just released ATM25 Radio Modem - call us for details on tnis great new AT&M kit Meanwhile check out ... 250gm $7.95 500gm $14.95 available in 0.7, 0.9 and 1.25mm diameters Save over $50 on this hard case set! Contains • Fluke 23 multimeter • Portasol Pro Gas Iron • Logic Probe • Xcelite Screwdriver Set e IC Puller and IC Inserter Set • HCK Probe Set • Solder Sucker • Pliers & Cutters All in rigid Fluke C100 hBBvy duty AT&M KITS Looking tor a ULTRASONIC CLEANER The latest high-tech way to clean PCB's, switches, watches, drafting pens - even your dentures! Let the millions of tiny cavitation bubbles clean the surface 40000 times per second. 165x90x50mm container holds half a litre and is made of 304 stainless steel. Some people are charging $200. Our's are only $160 . ., 5 AT&M Digital Storage Adaptor Kit Low cost accessory for your scope. Converts incoming analog signals up to 20kHz into a stream of 8-bit data words for storage in 2048 word memory. Ideal for one-shot observations. Replay as many times as you like. See description in E.A. December. Complete kit (AT&M17) using top quality components and with lull instructions is just $193.80 Matching case (ATM17-01) $27.60 ) , · '· Interface '83 All prices INCLUDE sales tax. $250 $5.00 We've still got IN4007's for only $1.50 for 25 -Yes that's Sc each 1 Taped and bent ready to go into your PCB. GEOFF WOOD ELECTRONICS PTY LTD 229 Burns Bay Road , (Corn er Beatrice St. ) INC IN Nsw Lane Cove West, N.S.W. P.O. Box 671, Lane Cove N.S.W. 2066 Telephone: (02) 428 4111 Fax: (02) 428 5198. 8.30am to 5.00pm Monday to Friday, 8.30am to 12 noon Satu rday. Mail Orders add $5 00 to cover postal charges. Next day delivery in Sydney add $5.00. "" :i:, r, j __. ,_.·_._.__, l J d---;..c_M_o_s_·a_a_H._11L_F_P_R1_c_E_s_10_.2...'5 $19 .50 CJ 0 We stick our necks out again because each time we advertise data books they sell out in days. OKI Wire Wrap Tool Finest quality We also stock wrap wire 0 ::r: National Data Books. '~-~j<:·,.:. ~~:;1;::::: ~':=:# ~ "'"ROSE ~ TO Z GlAOESVIUE BRIDGE . § .,, Tax exemption certificates accepted if line value exceeds $10.00. BANKCARD, MAS TE RCA RO, VISA , CHEQUES OR CASH CHEERFULLY ACCEPTED ~ a C) a "" :i:, r, ::r: j °t Jo 0 ~ss.1.11,:.---- -.. _ _ _ J........... _ I J....... L2... Here are the actual size artworks for the PC boards used in the 16-Channel Mixing Desk. They are as follows: SC01102901 (effects board - 2 required); SC01102902 (equaliser/VU board - 4 required); SC01102903 (preamplifier board - 16 required); and SC01102904 (power supply board - 1 required). 52 S ILICON CHIP 0 1 T'" 0 (.) ~ ~ 1--o 1 ;,_i O 0 ~ -- J sc~ 01102901 o-0 I MAY 1990 53 washers on the pots to allow this. Chassis assembly & wiring The chassis can now be assembled by installing all the sockets and plugs on the rear panel. The rear panel label for the effects and foldback sockets should also be affixed at this stage. In addition, the wooden side panels can be installed. The assembled front panel can now be laid face down on your workbench (still covered with a towel to prevent the panel being scratched), ready for wiring. The wmng is divided into three separate sections: the top and the lower sections of the panel, and the wiring between the control panel and the chassis components. We suggest that you begin by wiring the lower part of the panel; ie, the sliders, in/out switches and headphone sockets. To aid in the wiring process, we have included a chart which lists the colour of wire, the number of wires and the length required. This should be read in conjunction with the wiring diagram for each printed board. We recommend that constructors follow the wiring table in the order described for ease of construction. When wiring between the PCBs and the chassis, it is easier to keep the top panel lying flat on a table and the chassis lying on its back rather than the chassis standing on its feet and the panel upright. Mixer testing Once wiring is complete, go over your work carefully to check on any faults. These should be corrected before switching on the power. Keep the mixer in its wiring position with the front panel lying flat on the bench and the chassis upright for initial testing with the power switched on. When power is first switched on, immediately connect up a multimeter to check on the voltages applied to each PCB. Check that the power supply is delivering the ±15V and ±5V rails. If not, switch off immediately and check your connections again. Once the power supply rails are up and running, you can check the 54 SILICON CHIP Wiring Table For The 16-Channel Mixer LOWER PANEL WIRING Input Preamplifier PCB BLU 50mm x 1 4 between poles of in/out switches - foldback bus GRN 50mm x 1 4 between poles of in/out switches - effects bus RED 50mm x 14 between poles of in/out switches - CH1 /CH3 bus YEL 50mm x 14 between poles of in/out switches - CH2/CH4 bus Note: keep 1-8 and 9-1 6 buses separate RED 90mm x 1 6 headphone monitor socket signal to PCB GRN 90mm x 1 6 headphone monitor socket ground to PCB Note: readers may wish to connect the socket for mono operation with stereo headphones . BLK 11 0mm x 32 faders pins 2 and 3 to PCB BLK 180mm x 16 faders pin 1 to PCB BLU 80mm x 16 wiper of in/out switch to foldback out on PCB GRN 80mm x 16 wiper of in/out switch to effects out on PCB RED 80mm x 16 wiper of in/out switch to CH 1/CH3 out on PCB YEL 80mm x 16 wiper of in/out switch to CH2 /CH4 out on PCB BLU 70mm x 14 -1 5V power bus between PCBs RED 70mm x 14 + 1 5V power bus between PCBs GRN 70mm x 1 4 OV power bus between PCBs -1 5V power bus between 1 -8 input and 9-1 6 input BLU 100mm x RED 100mm x 1 + 1 5V power bus between 1 -8 input and 9-1 6 input GRN 1 OOm117 X 1 OV power bus between 1-8 and 9-16 input PCBs Equaliser/VU PCB BLK 11 0mm x 8 faders pins 2 and 3 to PCB BLK 1 80mm x 4 faders pin 1 to PCB RED 450mm x 1 CH2 bus from in/out switch to CH2 PCB YEL 450mm x 1 CH1 bus from in/out switch to CH1 PCB RED 1 90mm x CH4 bus from in/out switch to CH4 PCB YEL 190mm x 1 CH3 bus from in/out switch to CH3 PCB GRY 290mm x 1 CH1 headphone signal lead to CH1 and CH2 headphone socket GRY 290mm x 1 CH2 headphone signal lead to CH1 and CH2 headphone socket GRN 290mm x 1 headphone ground lead to CH1 and CH2 headphone socket GRY 150mm x 1 CH3 headphone signal lead to CH3 and CH4 headphone socket GRY 1 50mm x 1 CH4 headphone signal lead to CH3 and CH4 headphone socket GRN 1 50mm x 1 headphone ground lead to CH3 and CH4 headphone socket BLU 70mm x 3 + 1 5V supply bus between PCBs RED 70mm x 3 -1 5V supply bus between PCBs GRN 70mm x 3 DV supply bus between PCBs Effects PCB BLU 600mm GRN 600mm RED 220mm YEL 220mm BLU 300mm x 1 1-8 foldback bus to 1 -8 PCB x 1 -8 effects bus to 1 -8 PCB x 1 -8 CH2 bus at preamplifier PCB to CH2 PCB input x 1 1-8 CH1 bus at preamplifier PCB to CH1 PCB input x 1 9-1 6 foldback bus to 9-1 6 PCB GRN RED YEL BLU RED GRN BLU RED GRN BLU 300mm 170mm 170mm 100mm 100mm 100mm 70mm 70mm 70mm 110mm switch GRN 11 0mm switch RED 110mm YEL 11 0mm x 9-1 6 effects bus to 9-1 6 PCB 9-16 CH4 bus at preamp PCB to CH4 PCB input x 9-16 CH4 bus at preamp PCB to CH3 PCB input x x -1 5V supply bus on PCB to equaliser PCB x + 1 5V supply bus on PCB to equaliser PCB x 0V supply bus on PCB to equaliser PCB x 1 -1 5V supply bus between effects PCBs x 1 + 15V supply bus between effects PCBs x 0V supply bus between effects PCBs x 2 foldback bus from each effects board to 2/4CH x 2 effects bus from each effects board to 2/4CH x 2 CH1 and CH3 to 2/4CH switch x 2 CH2 and CH4 to 2/4CH switch TOP PANEL WIRIN G Input Preamp PCB Wiring of switch S1: single core shielded cable 70mm length x 6 per switch x 1 6 switches Equaliser PCB Bargraph Display Power Bus BRN GRN RED BLU 45mm 45mm 45mm 45mm x x x x 3 3 3 3 +5V bus between PCBs 0V bus between PCBs + 1 5V bus between PCBs -15V bus between PCBs CHASSIS TO FRONT PANEL WIRING Input & Output Wiring Figure-8 shielded cable 280mm x 1 6 from preamplifier input plug to PCB (note numbering of pins on rear of plug) Figure-8 shielded cable 51 0mm x 4 from equaliser output socket to PCB (note reversal of numbering on socket pins) Single shielded 400mm x 2 effects return input socket to 1 -8 and 9-1 6 PCBs Single shielded 4 1 0mm x 2 effects send output socket to 1-8 and 9-1 6 PCBs Single shielded 420mm x 2 foldback output socket to 1 -8 and 9-1 6 PCBs Power Supply wiring RED BLU GRN RED BLU GRN RED BLU GRN BRN GRN Twin 460mm + 1 5V preamplifier power supply bus to power supply 460mm -1 5V preamplifier power supply bus to power supply 460mm 0V preamplifier power supply bus to power supply 460mm + 1 5V equaliser power supply bus to power supply 460mm -1 5V equaliser power supply bus to power supply 460mm 0V equaliser power supply bus to power supply 230mm + 1 5V bargraph display supply bus to power supply 230mm -1 5V bargraph display supply bus to power supply 230mm 0V bargraph display supply bus to power supply 230mm + 5V bargraph display supply bus to power supply 460mm 0V on power supply to earth lug on chassis core polarised 480mm lead to power LED mixer operation with signal applied. Before you do this, switch off the power and attach the front panel to the chassis . Mixer testing is made easier if you have an XLR line plug for applying signal to the inputs, and an XLR line socket for measuring the output signal. Also, two mono 6.5mm line plugs are useful for measuring the Effects and Foldback outputs and applying signal to the Effects return input. Set the 2 Channel/4 Channel switch to 2 channel operation and set a channel input for "Line Unbal" mode. Apply a 100mV 1kHz signal to pin 2 or pin 3 of the XLR input socket input and check for signal at the CH1 output. With the input 1 PAN control set centrally, the CH1 and CH2 bargraph display should indicate the same signal level, provided the main faders are set equally. Adjust the PAN control to see its effect on the CH1 and CH2 outputs . This change will be seen on the LED VU displays. Rotate the input (pre-fade) attenuator (fully anticlockwise) and set the channel fader fully up . The overload LED should now be alight. Now reduce the signal with the attenuator until the overload LED is extinguished. Check also that the in/ out switch works and that you can monitor the channel signal output with headphones . Now test the Effects and Foldback outputs at the 6.5mm socket outputs. The signal levels at these outputs are adjustable with the Effects and Foldback Sends controls for each of the input channels and with the Effects and Foldback output controls . A signal can now be applied to the CH1/CH2 Effects return input to check that it is applied to the CH1 and CH2 bus . The CH1 and CH2 display should show the signal level and this is adjustable with the Effects return control. The pan control adjusts level between CH1 and CH2 . The remammg 2-8 channel inputs can be tested similarly and the entire 9-16 inputs can be tested with the signal measured at the CH3 and CH4 outputs . Finally, the Mixer can be tested for 2 channel operation. ~ MAY 1990 55 PHONEORDER TOLL FREE ALTRONICS 008 999 007 NEW! EXCITING, HERE NOW! Dear Customer, Regrettably, we're a little late in releasing this FANTASTIC "PRO SERIES ONE" amp. kiL We really tried our utmost to have the kits available in late February. However, some of the materials proved imposible to obtain until quite recently. Anyway, after burning the midnight oil, we now have a warehouse full of kits of this remarkable amplifier design. Everyone we've had listen to it is impressed. I'm sure you will too- imagine, 200 Watts per channel for less than $6001 Once again we apologise to all our customers who we have let down with late delivery. But, as a "peace offering", we are offering all our customers $50.00 off all orders placed for this product until June 30th (and of course to all back orders!) ~ ~ cf) Playmaster ··Pro Series One" High Power Amplifier Amazing 190W IHF into 8 Ohms! An outstanding high power stereo amplifier for you home HiFi, Disco, or Live PA system. as been carefully developed to produce a high definition audio output with renstructlon and low cost. The diecast front panel atsink. The chassis Is su · · (See EA December embles in · '89, January '90) PERFORMANCE Power Output (per channel wtth both channels driven) Continuous: 140W RMS into 8 Ohm - 200W RMS into 4 Ohms Harmonic distortion: 0.005% at 1DOW RMS into 8 Ohms Frequency response 10 Hz to 100kHz (-3dB points) Signal to noise More than 1OOdB below rated output (unweighted) nsitivlty 3V RMS for 100W into 8 Ohms rload Indicator if output distortion exc ) dividual toroidal transfer nnel for low residual hum. The Days Of Tape Decks Are Numbered * _ _."' This Digital Recorder delivers astonishing reproduction of voice and/or music without one single moving part! Digital Voice Recorder (Silicon Chip Dec'89) \~i~t \ · ' · Here is a digital voice recorder that can store 4 different signals, voice, sound or a music source of up to 30 seconds each or one recording of up to 2 minutes. This new digital voice recorder uses a special voice recorder/playback IC and 7 other IC's making it both simple to construct and incredibly economical. Separate 256K Ram chips are used for each channel. These memories can be ganged to provide a total of 2 mi!)JJtes of message time. There are 4 trigger inputs so that a message can be stored when a certain condition occurs. Battery backup is provided so that the messages are retained when main power is off. Typical applications include: • Alarm system messages • Sales messages for customers put "on hold"• Experimental telephone answering machine• Door station announcer• Talking displays for shops• Emergency warning message announcement • Operation instructor for machinery etc. For those who want a professional appearance - stand alone product, we can supply with K 9550 Kit complete- PCB Format $129.00 out Deluxe H 0483 Instrument case and fully punched and screen printed front panel. $149.oo Speech Synthesizer (ET/ March '88) Here is a self contained Speech Synthesizer that does not require a computer to control it. This small, simple circuit contains all the nc:ccssary components to make your favourite posscssicns speak. It can be connected to almost any appliance, vehicle or home remote control system to let you bi.ow when the kettle hu switclr.d off, the doors ue loclccd or the water in~ radiator is boiling. The inputs aic coded and priority message reading means warning, aic heard instead of greetings etc if two messages arc a:nt at the saIM time. Blank Eprom included to allow you to program the mcssag~s you want K9soo $SS.oo 895.00 K 9502 Pre-Programmed Eprom for K 9500 $20.00 FEATURES: • Sett contained circuitry • Simple double-sided PCB • Comes complete wnh speaker and Eprom • 12V DC operation SAVE $10.00 POWERHOUSE 600 Ge tery with th to choose fr (Sec EA Dcc'87) This inveru:r bu the capacity to produa: 600 watts of mains power which will run a fantastic array of appliances. Ideally BUitcd to numing power tools, lighting (including fluroo) electric motors and much more. It can be used cithc:r as a portable or a permanent fixture. • Manual CK" Auto Start facilities • Low battery WITH AuTo START Operates from 12V Car Battery 1 Auto Start draws power from your battery oo!y when appliance is plugged in and "turned on• ie, battery can be left permanently comcclcd if ~uiied. • Voltage Regulated • Current Regulated • Cuncnt Overload unit 1elf limits Complete Kit K 6750 $279.00 Fully built and tested K 6755 $379.00 e Silicon Chip Nov '87, Jan '88) uency Meter will out perform er instruments twice its price: K 2515 was $299.00 SAVES50.00 e: • Professionally machined and screen-printed red perspex Easy to assemble • Bright Hewlett Packard 8 digit display • h latching • High performance IC's • High Qualny components. Operational Modes: Period frequency to 100MHzfreq. to 1GHz Hz to 1GHz (1.7GHz typical) in frequency mode; 10Hz to 2.5MHz in period mode. Gating times: 0.01, 0.1, 1.0 and 10 seoonds · .128, 1.28, 12.8 and 128 seoonds (1GHz rang e). o - RF output - QUALITY ASTEC brand Just look at these applications I • Computer to TV • Video Games • Use TV as remote video monitor • Low Cost C RO adaptor for TV • Video recorder or camera to TV and so on. Completely sett-contained in PC mounting shielded case with RCA connector output. + 12V supply (case ve). Single terminal wire video input. Video Into RF Australian Channel $3.00ea, 10-24 $2.50ea, 25 and up $2.00ea Earns ifs cost hunderds of times over In cleaning connectors, PCB's, switches, jewellery, glasses, watches, drafting pens, etc. Awarded the Good roduct Design Award for CEIDC in 1987 SCOOP PURCHASE 19" RACK CASE MAGNIFICENT POWDER COATED FINISH? HUGE SAVINGS THIS MONTH! CAT NO. NORMALLY mm SPECIAL H 0404 GREY H 4014 BLK H 0405 GREY H 4015 BLK H 0406 GREY H 0416 BLK ( zx 00901 to 9 C (lnt,) J. Pin Point Wlll even clean your teeth! Won't scratch or damage - uses , ordinary tap wa.t.er and creates t milliOnJ of super-penetrating bubbles. Hospital tcm show that lnt:ruonic cleaning produce, better results safer than In just 3 minutes you w ill be amazed at the difference! LL Y $199.00, MONT T CAT NO. H 0431 GREY H 0434 BLK H 0432 GREY H 0435 BLK H 0433 GREY H 0436 BLK 44X254 88X254 132X254 .i NORMALLY 44 88 132 $U.95 $13.50 $25.95 DC Voltage: 200mV, 2V, 20V, 200V, 1000V AC Voltage: 200mV, 2V, 20V, 200V, 750V DC Current: 200uA, 2mA, 20mA, 200mA, 2A AC Current: 200uA, 2mA, 20mA, 200mA 2A, 20A Resistance: 200Ohm, 2kOhm, 20kOhm, 200kOhm, 2MOhm, 20MOhm, 200MOhm Capacitance: 2nF, 20nF, 200nF, 2uF, 20uF Inductance: 2mH, 20mH, 200mH, 2H , 20H hFE test, Diode test Price Breakthrough $40.00 $45-00 $50.00 VEL GEVE-..tl WAY! mm This truly fantastic bench Dlgltal Multlmeter + LCR, with capacitance and Inductance ranges, enable you to test a wide variety of components. lndlspenslble for the design engineer, technician and enthusiast alike. Q 1062 $59°95 $69.95 $85.00 SPECIAL $8.00 $9.00 $18.00 Why pay $400 or more for a David Clark set? AVIATORS HEADSET WITH OIL FILLED £AR CUSHIONS • High performance, noile attcm1ating ea,phones. • Noile cmcellittg microphone • Cushioned head pad • Super IJ!Urdy • Gteat performance • Superb, proft:ssional pilot's headset will last a lifetime with ""-=ble m:atmcnt. • Includes llandard airaaft jacb. c90100NL Y OURDfilECT IMPOllT PRICE LFSS THAN $1-00: Pocket Sized Personal Audio Signal Generator Qutte the finest portabel audio oscillator we have ever seen. Range switch and multiply enable selection to 46 preset frequencies from 20Hz to 150kHz, eg 20Hz, 28Hz, 32Hz, etc. Sine Wave and Square Wave outpuL Output control -20db to Odb Internal 9V battery $189.00 Now available from Altronics Dealers Q 1542 Oscillator VALUE Q 1544 Protective Carry Case $12.50 MULTI FUNCTION CAR ALARM WITH WIRELESS REMOTE ,.JU "~"c Sec EA April/May 89 Insulation breakdown cm in electrical wiring and appliance• can be detcnnincd with this dual range megohm.meter. ldcal for cbocldng insulation in tramformcn, appliances, automotive generators and altcmah'rl, houx wiring etc. Breakdown can be mouurcd at either SOOV or IOOOV depending on the situation. Perfect for work .. n, toolbox or work bench, K 2555 Wireless remote activate/de-activate alarm system and central door locking system (where fitted). Horn sounds to oonfirm armed. Light flashes to indicate disarmed. • VERY COMPREHENSIVE Comprehensive system protects from: • Bumping of car body eTowing • Window breaking • Forced entry of door boot or bonnet. HIGH POWER CAR ALARM \Vith \\Tireless Remote Control ~ * 9650$799 l0A/FUSE Pos. +Plugs into fuse box ~ t------~ YELLOW Direct Import Price! One of the moot compact handmld units to come from the UHF atable, this SW HandHeld weigh, in at just 470 gm, - including battery paclc. Features: • 5Watts audio utput power 40 channels Squelch control Power Hi/Lo ksy LCD displays Channel UP and WN keys Channel scanning Repeater channel rogrammng ,--B_LA_CK _ _ _ _ _-tlll• Earth RED S5225$129.OO HOW ABOUT THIS LITTLE BEAUTY? UNIDEN ROADRUNNER, 5WATT UHF40 CHANNEL CB TRANSCEIVER $79.00 VALUE Passive Infra-Red Lite Guard Door-s,trunk, ,hood etc. ~C~ Floodlight * Cont~ol ((<at>'~co>,._,, High Performance This alarm system will be triggered by unauthorised entrance through the car doors, boot, bonnet or removal of the car sound unit. The siren will sound and the headlights flash for 60 seoonds. Simple wiring, wire it yoursett without professional assistance. Automatic Reset s5220 0 N L Y $99.00 ELE(,'11.lET POWEllMIC. How often have you thoughtthere could be a prowler outside your door? Install a Lile Guard & (once armed) any "guest" will be floodlit when detected by thia highly sensitive Infra-Red Detector. Spectncatlons: • All weather operation• Operation Time, 1-2.0mins • Sensitivity: 20' - 50', 30 beams• Almable • Swltchlng Capablllty: 500W max. incandescent • Operation Modes: OFF, AlITO, TEST, MANUAL, ON. was $135.00 SPECIAL ONLY s 5350 $99.00SAVE Headlights t-BL_U_E_ _ Door switch circuit ~ For professional 2 -way radios on aircraft, boata, vehicle& and industrial PA systems. Fantastic voice clarity, absence of ft:edbaclc md boclcground noix with this microphone. Frequency response: 400Hz-8kHz This month only $15.oo 'i FERRO FLUID DOME TWEETER 100mm 60Watts Top end quality at a VERY n,asmable price. C 3012 Normally $29.50 each, Now$15.00 Save $14.50 Buy four '.,,.. c o3os Normally $29.80 for $50.00 Nearly ball price% lmpcdarn:e: 160 Ohms Sensltlvlty: -65dB (San from sound source) Requires l .SV battery Ill * Telephone Extention Bell Automatic Charger for Ni Cads INSTALLED IN MINUTES. Connects via P 0995 double adapter to telephone line at existing wall socket. Double adapter accepts both telephone and extension bell, which is supplied with a 10 meter lead. NOT SUITABLE FOR COMMANDER PHONE SYSTEMS.. VALUE (See EA July '89) Get 100's more recharge cycles from your nlcads Its now well known that correctly charging nlcad cells greatly extends their service Ille. Here is a fully automatic NiCad battery charger that enables differing charge rates as appropriate for AAA, AA, C, D cells or cells in series up to 9V. Once the battery is charged, the unit automatically switches to trickle charge until you switch it off. P0996 $29 .50 ~i" -:-, . - Hot Canaries - The Electronic Canary csmcon chip Feb'90) Get that atmosphere of tranquility that only birds can give. The realism of this project is remarkable. Sounds for all the world like two trilling canaries. • Battery po-red K1s50$39.5O ~ M 9020 (Plug-Paek Extra) $16,95 ~ *II K1130 $2S.95 Bel Express 3 Radar Detector Detects X, K and the new Ka Photo Radar Band. sw Industry standard! Express 3 contains the latest Bel breakthrough. Image Rejection Technology for KA band Photo Radar detection and twice the X and K band sensitivity of ordinary supsrhet radar detectors. NORMALLY $699.00 SAVE $IGO! A1540 Special Introductory price $599.oo 'Z Bel Express 3 - acclaimed the leader In Canada and USA - now available In Australla from Altronic. PROFESSIONAL QUAU1Y e BANKCARD e Fully equipped, Express 3 has no equal. SPECIAL Preprogrammed Features ■ ■ ■ ■ Instant On/Pulsed Warning: Encountering radar of this nature results in a warning sequence consisting of a series of quick "beeps" (unlike X, Kor Ka alerts) followed by the audio alert that corresponds to the type of radar received. Rashid VASS Rejection: Automatic rejection of signal received from collision warning systems which operate on the same frequency as police radar (K Band). Automatic K/Ka Band Override: Express 3 instantly alerts to the presence of K or Ka Band radar when the FSA mode is engaged. Automatic Test Sequence: Each time power is engaged, Express 3 will sound a single group of X, K, Ka and instant On/Pulsed alerts indicating it is ready to process police radar. VISA e MASTERCARD e PHONE TOLL FREE 008 999 007 e NEXT DAY JETSERVICE DELIVERY Country clients please allow an additional 48-72 hours MORE AL TRONICS DEALERS WANTED If you have a Retail Shop, you could increase your income significantly by becoming an Altronics Dealer, Phone Chris Campbell (09) 328 2199 for Details. 174 Roe St. Perth W.A. 6000 PHONE TOLL FREE 008 999 007 Perth Metro (09) 328 1599 ALL MAIL ORDERS P.O. Box 8350 Stirling Street Exchange Perth W.A.6000 AL TRONICS RESELLERS Chances are there is an Altronics Reseller right near you - check this l ist or phone us for details of the nearest dealer. PI••• Nole: Resellers have to pay the cost of freight and insurance and therefore the prices charged by individual Dealers may vary slightly from this Catalogue - m many cases, however, Dealer pnces will stall represent a significant cost saving from prices charged by Altronics Competitors. Don't forget our ExpreaI Mall and Phone Order Service - for the coat of a local call, Bankcard, Vlaa or M•tercard holder• can phone order for aame day deapaleh. Blue Ribbon Dealera are highlighted with a ■. These Dealers generally carry a comprehensive range of Altronic products and kits or will order any required item for you. STANDARD DELIVERY & PACKING CHARGE ss;so to 1Kg $8 over 1Kg AUSTRALIA WIDE - We process your order the day received and despatch via. Australia Post. Allow approx 9 days from day you post order to when you receive goods OVERNIGHT JETSERVICE Up to 3 Kg is $8.00- 3Kg to 5Kg is $20.00 - We process your order the day received and despatch via. Overnight JetHrvlce Courier for delivery next day Country areas please allow additional 24-48 hours. HEAVY HEAVY SERVICE - All orders of 10Kgs or more musttravel Express Road - Please allow 7 days for delivery. $12.00 to 10Kgs, $15.00 over 10Kgs. INSURANCE - As with virtually every other Australian supplier, we send 11oods at consignees risk. Should you require comprehensive insurance cover against loss or damage please add 1% to order value (minimum charge $1). When phone ordering please request "Insurance". TOLL FREE PHONE ORDER - Bankcard. Visa. Mastercard Holders can phone order toll free up to 6pm Eastern Standard Time. Remember with our Overnight Jetaervlce we deliver next day. COUNTRY ALBANY BP Electronics ■ 412681 ESPERANCE Esperance Communications 713344 GERALDTON Bird Electronics 641631 KALGOORLIE Todays Electronics ■ 212777 KARRATHA Daves Oscitronic 854836 PORT HEADLAND Ivan Tomek Electronics 732531 WYALKATCHEM D & J Pease 811132 NT ALICE SPRINGS Ascom. Electronics 521500 Farmer Electronics 522388 DARWIN Ventronics 480030 ACT CANBERRA Bennett Commercial Electronics 805359 VICTORIA CITY All Electronic Components 6623506 SUBURBAN CHELTENHAM Talking Electronics 5842386 CROYDEN Truscott Electronics ■ 7233860 PRESTON Preston Electronics 4840191 COUNTRY BENDIGO · KC Johnson ■ 411411 MORWELL Morwell Electronics 346133 QUEENSLAND CITY Delsound P/L 8396155 SUBURBAN CAPALABAKingsway Electronics 3902399 WOODRIDGE David Hall Electronics 8082777 COUNTRY BUNDABERG Bob Elkins Electronics 721785 GLADSTONE Supertronics 724459 MACKAY Philtronics ■ 578855 ROCKHAMPTONAcce.ss Electronics (East St.) 221058 TOOWOOMBA Hunts Electronics ■ 329677 TOWNSVILLE Solex ■ 7724466 MAROOCHYDOREMals Electronics 436119 SA CITY Force Electronic ■ 2125505 SUBURBAN BRIGHTON Force Electronics ■ 3770512 CHRISTIES BEACH Force El ectronics ■ 3823366 ENFIELD Force Electronics ■ 3496340 FINDON Force Electronics ■ 3471188 LONSDALE Force Electronics ■ 3260901 COUNTRY MT.GAMBIER South East Electronics 250034 WHYALLA Eyre Electronics ■ 454764 TASMANIA HOBART George Harvey ■ 342233 LAUNCESTON George Harvey ■ 316533 NSW CITY David Reid Electronics ■ 2671385 CARINGHAH Hicom Unitronics 5247878 COUNTRY COFFS HARBOUR Coffs Habour Electronics 525684GOSFORD Tomorrows Electronics 247246 GRAFTON East Coast Electronic 431250 NEWCASTLE Novocastrian Elect.Supplies 621358 RAYMOND TE"IRACE Alback Electronics 873419 WINDSOR M & E Electronics 775935 WOLLONGONG Newtek Electronics ■ 271620 Vimcom Electronics 284400 WAGGA WAG GA Phillips WA Something old & something new In this story, the old and the new were one and the same thing - an old model VCR that had been stored unused in its original carton for umteen years. But why did it seem to have so many separate faults? The device was a National video recorder, model NV300. This model is around 9 years old now and was, I believe, the last of the top loading models in this brand. They were very popular and are still worth servicing, in spite of their age. So the arrival of another one in the workshop was no surprise in itself. What was surprising was that the customer brought it in neatly packed in its original carton. What was more, even a cursory examination was sufficient to tell me that it had had very little use. Its history , as told by the customer, confirmed this. It had originally belonged to another member of his family but, for some obscure reason, had been packed away shortly after it had been acquired. He had only recently obtained it but had not been able to make it function. I'm not sure as to the precise details of that last statement. In view of subsequent events I suspect that, initially, there was some sign of life but that it failed to function properly. Subsequently, and possibly as a result of his attempts to correct this, it went completely dead (no channel indicator display lights, no clock function, etc }. Well, I've been caught myself with that condition on this machine and, even as we were unpacking it, I felt sure I knew the answer. One of the front panel controls is a pushbutton designated "Timer Ree Switch" . This is activated to put the machine into the timer controlled recording mode, after the start and stop times have been entered. And once it is activated regardless of whether the timer has been programmed or not - the set cannot be used in any other mode and appears virtually dead. This point is made in the instruction manual but is easily overlooked. While the customer was still there I plugged it in, connected it to a monitor and released the aforesaid button. The recorder immediately came to life. I set it up in the tuner mode and tuned in the SBS test card, which produced a first class picture. That piece of " magic " rocked the customer somewhat. Crook sound But even as I did this, I realised that all was not well. The picture was first class but the sound was so weak as to be almost non-existent. I made a quick check of the tuning adjustment but this achieved nothing. And the result was the same on several other channels. Finally, before the customer left, I tried a test tape. This loaded OK and tried to play but the picture refused to lock, suggesting a servo (RON\ta>.N ~ c . ~ r - , _ _ ~ CON~ S\JS'Pee.TED 11-\E- -"R~ CONve."R..,-E.R "-' & THE.SE C.OST OVE."R. '$ \00 I 60 SILICON CHIP BJI002-J BJI002- 2 BJI002 -J BJIOOl -4 BJl002- 5 BJ I002 - 6 BJI002- I BJl002- 8 Pl 002 AC l4V AC 14V • c1001 om _OY AC 22Y AC 36V AC 2.65V AC iii'/ ~ BJIOOJ - I BJI003 - 2 GN O BJIO0J - 3 --- -- BJI003-4 BJIOOJ - 5 BJI003-6 BJI003- I BJJ003 - 8 RIOOS RI003 3300 15K 8100! 56K RIOP2 5600 + CI004 - sov 0.33 P6008 - I P6008 - 1 P6008 - 3 P6008- 4 P6008 - 5 P6008 - 6 01002 2S0973 18.S OIOIS RIOOB 1100 MAl6~ I ZW o, ISS133 - C1001 OIOIG + ROl3EB2or3 CIOII l6V47 + 35V4 7 PIOOS [?ff-ffi -~ Fig.1: the power supply circuit for the NV300 VCR. An 18V regulated rail is provided by Q1002 while lesser regulated voltages are derived from IC1001. fault in either the drum or capstan systems. So we had at least two rather nasty faults and, on that basis, I had to advise the customer that repairs could be expensive. At the same time, I pointed out that, whatever the cost, he would be getting a virtually new machine for much less that its original value. It transpired that he felt the same way, so it was agreed that I should go ahead unless anything more serious showed up. RF converter Initially, I was most concerned about the sound fault. My prime suspect was the RF converter (modulator) and these cost over $100 to replace. On the other hand, the servo fault was unlikely to involve any expensive mechanical problems because the machine had had so little use. My first move was to replace the RF converter. I carry one of these in stock, expensive though they are. In fact, I carry several other major components under this brand even though they, too, are relatively expensive. While my accountant argues that such stock is hard to justify, purely on a turnover basis, I regard it as more than stock; it is also test equipment and relatively cheap test equipment at that, considering the time it can save on sticky jobs. The changeover is simple. The device clips into place and there is one multipin connector and the main RF lead to be changed over. And presto! - that cured the sound fault. So it looked as though we had a faulty RF converter. But the changeover revealed more than that. Now that we had normal sound level, running a test tape with a standard tone indicated that the tape was running spot on normal speed. On this basis, the capstan system appeared to be running at the correct speed, suggesting that the failure to lock the picture was most likely a fault in the drum servo system. The circuitry for the drum servo system includes IC2001 (MPC1504C) and its associated components (sheet 3-10 for those with a manual). Several waveforms are given and I checked these with the CRO. Unfortunately, results were rather inconclusive; the circuit was generating all the waveforms but with what precision was not easily determined. However, I had already developed a gut feeling that the servo system was trying to lock but couldn't quite make it. And that reminded me of R2022, a 50k0 trimpot labelled CYL.F.R. (cylinder free running). This trimpot is a coarse adjustment and sets the free running oscillator within the locking range of the servo system. While I had no intention of effecting a bodgie repair on a "twistand-fiddle" basis, I was anxious to know whether I could make the system lock, at least on a temporary basis. So, noting the present pot setting very carefully, I gave it a tiny nudge in one direction. And bingo - the picture jumped into lock. But it was something of a hollow victory because two more faults immediately presented themselves. One was that the picture had no colour and the other was that it was displaying very pronounced hum bars. Teetering penny My immediate reaction was one of surprise and frustration that a virtually new machine should have so many separate faults. Then I began to think a little more rationally. The penny - if it had not already dropped - was at least teetering on the edge. It was the hum bars that provided the vital clue. This meant a fault somewhere in the power supply and this would have to be fixed before going any further. What was more, there was good chance that at least some of the other faults were manifestations of this one. So I went straight to the power supply (sheet 3-8). This delivers a number of voltages, some AC but most regulated DC. An 18V supply is derived from regulator transistor Q1002 but the other regulated supMAY 1990 61 believe it or not, it now delivered perfect sound. So that was it. I threw in a routine clean and lubrication and the customer now had a virtually new machine, with first class performance. And it had cost him less than the price of the RF converter which I had feared I might have to supply. SERVICEMAN'S LOG -CTD Post mortem ~I ~ J I · . \ .. CZ(~L 0. 0 •. MY IMME:"'DIPt"f'~ 'RE:AC.-,101'1 WP-.S Ol= SU'RPR\"SE & FR~TION 11-\F,r ~ V\RTUP--U...'-< NE:W MP...CH\l\lE: ~\-\OU\...D k~\JS SO MAN\.f Ff\UL-TSoo~ plies come from IC1001 (STR1096). The 18V rail was spot on so I went to the IC which is readily accessible. Pin 1 is shown as 15.1 V and was spot on. Pin 2 is shown as 11V but was actually 14.8V. Pin 3 is chassis. Pin 4 is shown as 9.31V but was 13.6V. Pin 5, shown as 6.06V, was OK. The answer, of course, was a crook IC. They are a common enough device and I had one in stock, so it was easy to replace it. The result was more far reaching than I expected. The colour was 62 SILICON CHIP restored and the hum bars had vanished, which I did expect. I wasn't sure about the locking problem but felt I should reset the CYL.F.R. pot. This I did and the system not only remained in lock but exhibited a wide locking range. That left a query over the RF converter. I wasn't very confident that the power supply fault was to blame here, seeing that the replacement converter had worked, but it was simple enough to try and there was a lot of money at stake. So, in went the original converter. And But there is rather more to the story than that. I have to admit that, in hindsight, I should have done better. Experience has taught me that whenever I encounter more than one fault in a video recorder - and particularly if they appear to be unrelated - the first thing to check is the common factor; the power supply. Had I done so, I would have saved some time. But why did the power supply fault have the effect it did, particularly in regard to the RF converter? Well, for starters, let's consider the voltage delivered by pin 4 of IC1002 - 9.3V. This supplies the RF converter, the servo circuits, and the luminance and chominance circuits. The faulty IC gave a pin 4 voltage of 13.6V and this accounts for all four symptoms, at least in general terms. But why did one RF converter accept this fault while the other one wouldn't? My best guess is that individual modules may vary in their sensitivity to such a fault; some may work with it, some may not. At least, that's my theory. Amateur gear And now, for a complete change of scene, here's a story with an amateur flavour. I usually don't have much to do with amateur equipment as such devices are not really within my field. But every now and again my amateur friend encounters a problem and seeks my assistance - which I'm happy enough to give within my limited experience. On this occasion, the problem concerned his 2-metre transceiver; an learn Model 22S. I understand that these were a very popular unit some years ago, being regarded as very much state-of-the-art when they were introduced. They were TETIA TV TIP Sanyo CTP 7605A Symptom: No go. No voltage between collector & emitter of chopper transistor but normal output can be measured across bridge diodes. Fuses and primary of chopper transformer are OK. Cure: Dry joint at mounting post of C310. The can of this large electro forms a link between the bridge negative and the emitter of the chopper transistor and the two mounting posts must be securely fixed to the copper track. TETIA TV Tip is supplied by the Tasmanian branch of The Electronic Technicians' Institute of Australia. Contact Jim Lawler, 16 Adina St, Geilston Bay, Tasmania 7015. also regarded as good value for money. One of their features was a phase locked loop (PLL) to replace the bank of crystals employed in the previous model, the Icom 22. Such models were normally supplied with two or three sets of crystals of the customer's choice. After that, the owner had to supply his own crystals for whatever channels he chose. But crystals are expensive and not always easy to get for a particular frequency. So the PLL was a significant improvement, permitting operation on virtually any channel across the 2-metre band. Various switching systems were employed to select the wanted channel. The Icom 22S used a novel approach. It was equipped with a matrix board to which the owner could fit inexpensive switching diodes in a wide range of configurations to produce a chosen frequency. Each diode combination was fed from a 9V rail and there were 22 such rails, selected by the channel switch. Each diode in any one combination fed one of eight cross rails. Typically, from one to seven diodes would be needed for a particular channel. Thus the user could program the set for up to 22 channels. However, it didn't take the mob long to wake MASSIVE TEST EQUIPMENT SALE Completion of Various Contracts Allows Us To Offer Equipment Surplus To Requirements Racal Laboratory DVM Model 5005 - $1 200 Racal Laboratory DVM Model 5004 - $1200 Racal Laboratory DFM 9000 Series - $1400 Heathkit Transistor Tester IM-36 - $30 Hewlett Packard HP606A Signal Generator 50kHz-65MHz - $500 Hewlett Packard HP41 QC Voltmeter with Probe (900MHz) - $350 Marconi TF 886A Q Magnification Meter 1 5-180MHz - $1 50 Hewlett Packard HP614A UHF Signal Generator (800MHz-2.2GHz) - $250 Marconi TF2092 Noise Receiver (75!l) - $50 Hewlett Packard HP6188 Signal Generator (3.8-7 .6GHz) - $200 Marconi MF Monitored Attenuator DC-550 kHz, 0-11 0dB , 0.1 dB Steps - $100 Wayne Kerr Universal Bridge 8224 - $350 Hewlett Packard HP 86548 Signal Generator 1 0-520 Mrlz - $2500 Gilmac RF Bridge, 20-180 MHz, Digital Frequency Readout, Direct SWR Readout $2500 Advance Power Supply PP15 0-15 Volts 0-3 Amps - $100 Gilmac DC Power Supply 13.8 Volt 25 Amp Continuous, Rack Mount, Fan Cooled , New - $400 Systron Donner Pulse Generator Model 101 - $250 General Radio 1564A Sound & Vibration Analyser, 1/3-1 / 1 0 Octave Level Meter $150 Gilmac Lab Power Supply 0-15V 0-10 Amps Metered, New - $350 Singer Microwave Spectrum Analyser, IF Section Only, 1 kHz Resolution - $200 General Radio 1156A Decade Scaler, 100MHz in 10MHz Out - $50 Siemens D21 55 Level Meter With W3155 Tracking Oscillator 200Hz-61 0kHz Digital Readout Current Model - $3500 Tektronix 454A 150MHz Oscilloscope - $1350 Tektronix 453 50MHz Oscilloscope - $950 Bruel & Kjoer Electronic Voltmeter Model 2416, 2Hz-20kHz, Displays DB, DBM , Volts (RMS, AV, PEAK) - $60 Systron Donner Spectrum Analyser 762-2A 1 0MHz-40GHz CW, All Waveguide Mixers 1 kHz IF Resolution - $4000 Green Screen Video Monitor P31 Phosphor Composite Video Input - $50 Hewlett Packard HP200 CDR Audio Oscillator 5Hz-60kHz , 20V RMS 600V output $80 Micro Power Model 221 Sweep Generator 8-12 GHz, AM - Pulse - $250 Tektronix CRO Tubes 5-lnch New: 1 x TO541-31, 1 x TO501-7 P/No. 154/0082 $100 Each Racal Laboratory Pulse Generator Delay, 1500 Series, As New - $1200 Racal Logic State Analyser 205 With All Options, As New - $10,000 Racal Universal Switch Controller, 1200 Series, As New - $1200 Racal DFM 1 0Hz-3GHz, 9921, as New - $1000 Racal DFM 1 0Hz-200MHz, 9913, As New - $250 Racal DFM 1 0Hz-200MHz, 9914, As New - $450 HP Spectrum Analyser 0-1200MHz 141T - $2500 Avo Bridge G2457/6, As New - $300 Avo Super Megohmmeter RM 170, As New - $400 Racal-Milco Transmission Test Set, Model 220, As New - $350 Swan-Astro 102BX HF Transceiver, 150 WRF, As New - $750 CCD Subminiature Camera, Auto Iris Lens, 0.5 Lux Sensitivity With CCTS, As New $400 Racal HF Transceiver, 7948, 100 Watt, New, 24V with CCTS - $750 Bruel & Kjoer Artificial Voice Model 4219 - $150 Drake SSR1 Shortwave Receiver - $100 Call, Fax or Write: AV-Comm Pty Ltd, PO Box 386, Northbridge, NSW 2063. Tel: (02) 949 7417; Fax: (02) 949 7095. All Reasonable Offers Accepted. MAY 1990 63 View inside the Icom 22S, with the matrix board hinged forwards. The fault was discovered on the sub-hoard, beneath the matrix hoard. to the fact that there was a 23rd positio'n on the switch and the matrix board, and that these could be wired to an external combination of diodes and switches which could select any channel at will, over and above the permanent 22. All in all, it is a very versatile arrangement. In common with all 2-metre transceivers using a PLL, there is also an offset function. For use with repeaters, it separates the transmit and receive frequencies by 600kHz (the standard repeater separation). The dark side Unfortunately, there was a dark side to this model. It is now generally acknowledged that some batches suffered from a crop of dry joints, particularly on a sub-board situated beneath the main PC board. This sub-board carries the PLL, voltage controlled oscillator, offset circuit and a plug for the matrix board. In most cases, these dry joints could be cured by blanket resoldering. So what was my friend's problem'? The set normally serves as a base station but can also be used as a mobile unit in his car. And it all started when he fitted the set in his car and travelled north for the Gosford Field Day - an annual event normally attended by every amateur and his dog within a 200km radius. The set performed perfectly during the day but was used only in the simplex mode. It was not until he returned home, set the unit up for base operation, and tried to activate his favourite repeater, that things went wrong. The set has two indicator lights .1.m.,,;. ;r.~1;i1:.1;: RCS Radio Pty Ltd is the only company which manufactures and sells every PCB E, front panel published in SILICON CHIP, ETI and EA. 651 Forest Road, Bexley, NSW 2207. Phone (02) 587 3491. 64 SILICON CHIP on the panel: a green one to indicate an incoming signal and a red one to indicate that the transmitter is on. When he pushed the PTT button, the red light came on all right but so did the green one; a clear indication that something was wrong. More to the point, the repeater did not respond. After a couple of more tries, the green light ceased to show and the indications were that all was now well. But there was still no response from the repeater, despite the fact that the set's own power meter indicated normal RF. Several other repeaters were also tried with the same result. At this point, my friend assumed that vibration during the car journey had unearthed one of the aforesaid dry joints but he was puzzled as to why the set appeared to be delivering normal RF but could not access any repeaters. To confirm the RF output, he connected a dummy load and made a power output measurement. It was spot on for this set. So, if it was delivering power but not reaching the repeater, it was most likely that it was off frequency. And that's where I came into the story. The first I knew of his problem was when he approached me, and requested the loan of a frequency meter. I don't use the meter much so I was happy enough to agree, wishing him luck as I handed it over. Later, he filled me in on subsequent events. He connected the frequency meter to the dummy load tapping which normally feeds the power meter, switched the set to low power, and pressed the button. The meter should have read 147.875 MHz but actually read 147.675 MHz; ie, 200kHz low. Several other repeater frequencies were tried, all with exactly the same result. But something else emerged from these tests; the problem was confined to the offset function. When the transmitter was switched to the simplex mode, all frequencies were correct. At this point my friend decided to do a little judicious prodding around the suspect boards. If that continued on page 99 . PRCCESS COMMUNICATIONS PTY LTD • • • • Continuous coverage from 150KHz to 30MHz. AM/CW/SSB, Inbuilt RF gain control, BFO. PLL synthesised tuning, LCD display. Scanning, 14 memories, AM broadcast AS REVIEWED & FM stereo coverage, 12 short wave bands. IN SILICON CHIP, Cat # C5020 $299.00 JUNE '89. • Optional AC adaptor Cat # T0941 $24.95 • Miniature size. • Complete with personal stereo headphones. • Includes short wave listening guide. • Great "leather look" carry case. • AM broadcast and FM stereo coverage. Cat # C6000 $119.00 • Optional AC adaptor Cat # T0321 $19.95 • • • • 6 short wave bands. AM broadcast. FM stereo. Protective carry pouch and shortwave guide. Cat # C6020 $79.00 • Optional AC adaptor Cat # T0320 $19.95 •- iir • Continuous shortwave coverage 5.8MHz to 15.5 MHz. • 25 memories. • Auto timer functions. • Up/down tuning control in 5KHz steps. • AM broadcast and FM stereo coverage. Cat # C6028 S199.00 • Optional AC adaptor Cat # T0630 $24.95 • Slightly larger than MS-101 but with 10 short wave bands. Cat # C6010 $119.00 • Optional AC adaptor Cat # T0321 $19.95 • Scan, search , lock-out, hold , delay functions. • Frequency coverage 60MHz-90MHz, 138MHz-174MHz, 406MHz-525MHz, 830MHz-950MHz. • Selectivity: 7.5KHz at 6d8. • Audio output: 120mW. • Size : 140mm (H) x 55mm (W) x 44mm (0) . I'"'' Cat # C5020 $399.00 • Optional AC adaptor 2 • Up/down push Cat # T0620 $19.95 button channel control. • Easy to read red LED channel display. . • Miniature size suits installation in modern vehicles. • Maximum legal power output. Cat # C5100 $79.00 SPECIAL INTRODUCTORY OFFER - SAVE $10.00 • Scanning, lock out. Hi-Lo power controls. • Programmable repeater operation . • Optional tone squelch available. • Back-lit LCD display. • Maximum legal 5 watt output. • Includes rechargeable ni-cad battery. Cat # C5047 $599.00 Available Accessories: ~~X a) Speaker microphone Cat II C5050 $49.50 b) Drop in desk charger (including fast and slcm charge rates) Cat II C5052 S129.00 c) Glass- mount half wave antenna no holes to drill! Cat II 1<3095 $79.00 d) Mobile transceiver adaptor - adapts your AA-477 to mobile configuration. Includes full mounting hardware ideal tor use with a) & c) above. Cat II C5054 S129.00 e) Spare 10.8 volt, 500mA ni-cad battery. Cat II 1<3090 $69.00 f) Communications headset Cat II K5060 $49.00 g) Vox-unrt - allows handsfree operation using headset f) above Cat II C5055 S69.00 h) Tnckle charge AC adaptor Cat II TD12D $19.95 • Similar to SG-796 above, but includes 6 shortwave bands, VHF air band and long wave band. Cat # C6025 $79.00 • Optional AC adaptor Cat # T0320 $19.95 I . ·-·... ~- ffl ~!l'~ - ... - • High/Low power switch. • Scan , priority, dual watch, up/down channel control. • Auto seaphone compatible. • 54 trans mit and 57 receive channels. • DOTC Approval # 274B0090. Cat # C7000 $299.00 SPECIAL INTRODUCTORY OFFER (to suit above): Cat # C7005 $159.00 Wired to suit C7005 transceiver. • Includes 4-way polycarbonate UV stabilised base and coaxial cable. • Weather-proof fibreglass radome. • Ground independent half-wave design. Cat # K3162 $69,00 • Suits mobile or desk-top installation. • Frequency coverage : 60MHz-90MHz, 118MHz-174MHz 430MHz-512MHz, 830MHz-950MHz. • Search increments: 5KHz, 10KHz, 12.5KHz, 25KHz, 30KHz. • Search , scar., priority, lock-out, delay/hold, AM/FM functions. • Supplied with 2.antennas for optimum UHF and VHF reception. • Inbuilt 20dB local/DX attenuator. Cat # C5015 $499.00 • Optional AC adaptor Cat # T/230 $24.95 • • • • Mail Orders Welcome Phone Orders Accepted Same Day Despatch Free De/Ivery Bankcard/Mastercard/Visa Welcome The Mozzie CW Transceiver This nifty little transceiver is an unconventional design. It is suitable for Morse and RTTY and has a maximum power output of about 1 watt. It is battery powered and its output has a low harmonic content less than - 40dB. Design By CLIVE CHAMBERLAIN For a long time now there has been a crying need for a low-cost low-power transceiver which could be used by amateurs for Morse and RTTY communications. In the past, there has been a number of designs but there has been nothing which used readily available up-to-date components. Now that has changed and we can present the "Mazzie" which is 66 SILICON CHIP right up to the minute in its circuit design and performance. Designed and supplied by Australian Test and Measurement Pty Ltd, the Mazzie uses 5 integrated circuits and is built on a small double sided PC board. The top of this board is a ground plane which has been included for stability and freedom from noise. The Mazzie is housed in a low profile case. On the front panel there are two toggle switches, one for power and the other for transmit/receive [Tx/Rx) switching. There is also a volume control knob for the receiver function. On the rear panel, there are three insulated RCA sockets and a 6.35mm jack socket. The RCA sockets are for 6V DC input, a Morse key and the antenna connection, while the 6.35mm jack socket is for the headphones. The design could be adapted to operate anywhere in the amateur 6-metre band but has been optimised to suit the readily available American US colour TV intercarrier crystal at 3.58MHz - more precisely 3.579545MHz. We expect this frequency to become quite popular for Mazzie operation maybe it will become the "Mazzie Net"! Design features The Mozzie is a single channel CW (Continuous Wave - Morse Code) transmitter and receiver with a maximum power output of about 1 watt at 3.58MHz. The receiver is a direct conversion type (ie, not superheterodyne) which uses an oscillator frequency slightly offset from that of the transmitter. This is done by shifting the crystal frequency slightly when the transmitter function is selected. Now have a look at the circuit of Fig.1. This is split into two sections with the transmitter being along the top (IC1 and IC2) while the receiver is along the bottom of the diagram (IC3, IC4 & IC5). Both the receiver and transmitter use a common antenna with switching between the two performed by switch S1, at the top righthand corner of the diagram. Let's look at the receiver circuit first (Fig.1 ). Direct conversion receiver Incoming RF signal from the antenna is applied via switch S1 to the two bandpass filters comprising L6, L7 and two 33pF capacitors, and top coupled by a 6.BpF capacitor. These bandpass filters are centered around 3.58MHz and heavily attenuate frequencies more than about ± 50kHz either side of this frequency. This is necessary to block out broadcast radio, TV and any other transmissions not on the "Mozzie Net". Balanced mixer The heart of the receiver is IC3, a Signetics NE602 which is a double balanced mixer and oscillator. In this circuit, the internal oscillator is not used and an external oscillator, ICld, is used instead. Its output is fed into pin 6 of IC3 via a 5.6k0 resistor and l00pF capacitor. The "beat" output from IC3 is taken from pin 4. If both the transmitter and receiver were operating from exactly the same crystal frequency, there would be a "zero beat" from the mixer but as we have already mentioned, there is normally a difference between the two and this " beat" is an audio frequency. The beat note from pin 4 of IC3 The Mozzie uses 5 integrated circuits and is built on a small double-sided PCB. The top of the board is a ground plane which has been included to ensure stability and low noise. also contains a lot of the 3. 58MHz local oscillator signal which is filtered out by the 4.7mH inductor L5 and the a ssociated .022µ F and .033µF capacitors before being fed into the following audio stage. The NE602 does contribute quite a useful amount of conversion gain (about 100 times) and we need all the help we can get because the incoming signal is likely to be only a few microvolts of RF. So IC3 functions as a direct conversion receiver, with the incoming RF demodulated directly to audio without going through an intermediate frequency a s in a superheterodyne. This has the advantage of simplicity but some of the feature s of the superhet such a s RF derived automatic gain control to stabilise audio output level are sacrificed. The low level audio which may be at a few hundred microvolts is now passed to IC4a which is half of a low noise LM833 dual op amp. IC4a is connected as a non-inverting amplifier with a gain of 100. The audio output from pin 1 of IC4a now would be typically 30 to 50 millivolts. Limiter stage The next stage is IC4b which is the other half of the LM833. This functions as an audio limiter by virtue of the back-to-back silicon signal diodes D4 and D5 in the feedback loop. This provides a form of automatic gain control which prevents perforation of the ear- Where to buy the kit A complete kit fo r the Mozzie 3.58MHz transceiver is available from Australian Test and Measurement Pty Ltd, 28 Hotham Parade, Artarmon, NSW 2064, or fro m any of their dealers. See the advertisment in this issue. Phone (0 2) 906 2333 . The cos t of the kit is $84.50 plus $6 .50 postage and packing. MAY 1990 67 PARTS LIST 1 plastic instrument case, 140 x 110 x 46mm 1 PC board, 84 x 102mm 1 front panel artwork 1 rear panel artwork 1 6.35mm jack socket 3 insulated screw mount RCA sockets 2 1 0 way PCB connector strips 2 PCB mount SPOT miniature toggle switches 1 3.579545MHz crystal 1 knob 1 balun core 1 1OOkO linear potentiometer (VR1) Semiconductors 1 75451 dual peripheral driver (IC1) 1 7 4HCOO CMOS quad NANO gate (IC2) 1 NE602 double balanced mixer (IC3) 1 LM833 dual low noise op amp (IC4) 1 LM386 power amplifier (IC5) 7 1N4148 diodes (01 to 07) Capacitors 3 1OOOµF 16VW PC electrolytics 5 1µF 35V tantalum electrolytics 4 0.1 µF monolithics 2 O. 1µF metallised polyester 1 .033µF metallised polyester drums should a nice strong signal, say 50 microvolts, be received at the antenna. IC4b limits the signal at the function of the lOkO resistors to about 100 millivolts RMS. Note that this limiter is not suitable for speech signals since it clips heavily; the resulting distortion would be ghastly. With a continuous tone "beat" though, it is quite acceptable; it just sounds a bit "edgy". The signal from the limiter stage is applied to volume control VR1 and then to IC5, an LM386 amplifier which can drive an external loudspeaker or headphones. Thorough decoupling is provided for IC3, IC4 and IC5 with lOOOµF electrolytic capacitors. Without this decoupling, feedback via the supply line would lead to "howling" 68 SILICON CHIP 1 1 3 4 1 1 2 1 1 .022µF metallised polyester .001 µF metallised polyester 560pF polystyrene 220pF ceramic 1OOpF ceramic 82pF ceramic 33pF ceramic 6.8pF ceramic 6-45pF trimmer (VC1) Inductors (chokes) 3 2.2 microhenries (L 1, L2, L3) 2 33 microhenries (L6, L7) 1 180 microhenries (l4) 1 330 microhenries (L8) 1 4. 7 millihenries (LS) Resistors (0.25W, 5%) 1 1MO 3 100k0 1 15k0 4 10k0 2 5.6k0 2 4.7k0 1 1k0 1 4700 1 1000 2 1 000 ½ W (for dummy load) 1 4 70 ½ W (for supply current limiting) Miscellaneous 0.3mm enamelled copper wire, hookup wire, solder, 6V battery pack (4 alkaline AA cells plus holder) . due to the high gains and compact assembly. The ground plane construction of the printed circuit board is also a safeguard. Squelch feature D1 and D6 form an audio mute system to block audio from reaching the LM386 while the Mazzie is transmitting so as not to be distracting. When the Tx/Rx control switch is set to Transmit, about 0.8mA is fed through the diodes so that they become a low impedance. This shunts the audio signal away from the input of IC5 via a lµF capacitor and so the circuit is effectively muted. Crystal oscillator The crystal oscillator is based on IC1d, a standard HCMOS NAND gate biased for linear operation by the 1MO feedback resistor which keeps its output at about 3V. The crystal and the "tweaking" components, VC1 and L4, form a feedback loop which causes the NAND gate to oscillate at the crystal's fundamental frequency of 3.58MHz. The crystal oscillator runs all the time, whether in Transmit or Receive mode, but during Transmit, diode D7 is forward biased via its associated 10k0 resistor. This bias gives D7 a low resistance and it effectively shorts out VC1 and so slightly reduces the crystal oscillating frequency. IC1c forms an inverting buffer for the crystal oscillator's output from pin 11 and also drives a charge pump consisting of diodes D2 & D3. This charge pump produces a + 4V DC supply for the Morse key input. This is a safety feature for the power output stage of the transmitter. It proved neccessary because if the crystal oscillator does not oscillate no Morse key supply will be produced and so the transmitter cannot be keyed on. The 3.58MHz square waves at pin 11 and pin 8 of IC1 are of opposite phase and are fed via IC1a and IC1b which gate the signal through to the output stage when the + 4V Morse supply is applied to pins 2 and 4 via the Morse key. In this way, push pull drive is fed to the transmitter output stage. Transmitter output stage Readers who are familiar with transmitter output stages may be puzzled when they look at the photos and wiring diagram for the Mozzie - where are the RF output transistors? The answer is that there are no discrete transistors in the circuit. The RF output transistors are contained in IC2, a 75451 dual peripheral driver made by National Semiconductor. This is an odd device to find in a transmitter circuit. It is normally Fig.1: IC1, IC2 and crystal X1 form the transmitter while IC3, IC4 & IC5 make up a direct conversion receiver. Both the transmitter and the receiver share a common antenna which is switched between the two by S1. i I t ANTENNA ~ r II ---:--0 ~ 01 · ♦ tu m• 470{) f +6V S1 RX 14 220pF 10k 1M VC1 X1 3.579MHz 6-45pF D7 ol----'oo' • 180uH 100k 0.1+ 1N4148 L4 .,.. KEY • D2 1N4148 10k 82pF! T 0.1! .,. I f ! l 1 ~ 4.7k ... ~ ! 1000! l ✓.,_<r-Qsv S2 '::r:'DC .001 100k 220pF D1 1N4148 1000! o.,I D5 2x1N4148 I .,. 220pF ~ 1k ~ -< ..... 1+ co co 0 THE MOZZIE CW TRANSCEIVER ~ cc 1 +--- VD~~~E~ 1Dk 1000 SPEAKER OR HEADPHONES •·a:---:--v I " +· } .,.. ~ Fig.2: keep all leads as short as possible when installing the parts on the PCB and don't forget to solder on both sides of the board where required (note: ground plane not shown). Don't forget to solder the front flange of switch S1 to the ground plane pad provided. intended for use in high speed buffers, relay drivers and other peripherals for logic circuitry. It contains two TTL NAND gates and two NPN transistors which are rated for operation at up to 30 volts DC. The two NAND gates in ICZ are connected as inverters and they each drive an internal output transistor which then both drive pushpull transformer Tl and a tank circuit consisting of 11, 12 & 13 and the associated 560pF capacitors. The tank circuit filters out the harmonics of the transmitter waveform so that the signal fed to the antenna is a clean sine wave. Actually this gating and driving arrangement has more in common with a switch mode power supply than a radio transmitter, but modern high speed logic devices make this transmitter line up much simpler and more efficient than would probably be the case with tuned RF stages and an output tank, especially considering the low supply voltage of 6V! On receive, the current drain from the 6V battery pack is about BmA and on transmit up to about 250mA. If you use four "AA" alkaline cells as your battery pack, you should get a lot of air time, considering typical Tx/Rx duty cycles. Assembly As noted previously, the Mazzie is built on a double sided printed circuit board with the top function- ··w SECONDARY 6T, 0.4mm DIA ENCU PRIMARY 2x4T, 0.4mm ENCU BIFILAR WOUND ON CENTRE LIMB OF FERRITE BALUN CORE Fig.3: winding details for the RF output transformer. After winding, use your multimeter to identify the correct connections for making a centre-tapped primary. TABLE 1: INDUCTOR CODES 70 L 1, L2, L3 L6, L7 2.2µH 33µH red red brown gold orange orange black gold L4 180µ,H brown grey brown gold L5 L8 4.7mH yellow violet red gold orange orange brown gold SILICON CHIP 330µ,H ing as a ground plane. The board is housed in neat low profile plastic case which is supplied in the complete kit for the project which comes from Australian Test and Measurement Pty Ltd. Price for the complete kit is $84.50 while packing and postage to any part of Australia is $6.50. To keep costs reasonable, the double side printed board does not have plated through holes, so quite a few topside joints are necessary to complete the circuitry. These joints will be easy to spot however, as they will show through the top green solder mask. Start assembly by loading the lowest height components first , such as the diodes and resistors . Next, the ceramic capacitors can be loaded and soldered. Philips types have been used for the smaller values to 220pF. These have tiny flanges in their leads, just below the capacitor body, which fixes their height above the PCB and makes an ideal soldering point for the topside joints. The 0.lµF monolithic ceramic capacitors have a kink in both their leads which serves a similar function. The chokes can go in next. They look just like resistors and have the same colour code bands except they have thicker bodies. Colour codes for chokes (inductors) are based on multiples of microhenries. So, if a 4. 7 millihenry 5 % choke is called for, the colour is yellow, violet, red, gold. The colour codes for all the inductors are shown in Table 1. The ICs go in next, followed by the plastic, tantalum and aluminium electrolytic capacitors, while making sure that the polarities are correct. Once these are mounted the PCB-mount switches can go in'. Remember to solder the front flange of Sl to the ground plane pad provided. Before installing the volume pot, VR1, cut off the flattened section of the shaft. The RF output transformer, Tl, must be wound according to Fig.3, with the number of turns and direction of winding being exactly as shown in the diagram; 4 turns each for the primary windings and 6 turns for the secondary, all with The Mozzie transceiver is powered from an external 6V battery pack. Do not apply more than 6V DC to the circuit. 0.3mm enamelled copper wire. Strip and tin the four primary leads so you can use your multimeter, switched to a low "Ohms" range, to identify the correct connections for making a centre tapped primary. The twisted centre tap must be soldered to the top and bottom pads on the PC board. The other transformer leads can now be pushed through their PCB holes and soldered to the bottom side. Receiver testing The Mozzie should be tested before being mounted into the case, so first attach the four hexagonal standoff posts to the bottom of the PCB using the screws provided and use the 10-way pinstrips to connect to the matching socket strips on the PCB. For preliminary testing of the RF circuits, a dummy load consisting of two 1000 ½ W resistors in parallel should be connected between te AAA and GG terminals on the S2 connector and say 5 metres of hookup wire as a temporary antenna also to AAA. A pair of stereo headphones with both channels commoned or a small speaker can then be connected between the SS and the GGs on the S2 connector. For the 6 volt supply, a regulated power supply with current limiting is best for this procedure but a 6V battery pack with a series current limiting resistor of 470 can be used as an alternative. When connecting the supply, make sure that the polarity is correct, otherwise you'll damage the circuit. Set the volume control fully anticlockwise (minimum setting) and the transmit/receive switch to Rx. Turn the Mozzie on. Check that the positive rail (between + 4.5 and + 5.5V) is present at pin 14 of ICl, pin 8 of IC2, IC3 & IC4, and pin 6 of IC5. Now check for around + 3V at pin 1 of ICl, pin 1 of IC4 and pin 5 of IC5. Any major deviation from 3V could mean incorrect assembly or missing solder joints. Around 3V should be present at pin 11 of ICl. Also present at pin 11 of ICl should be the 3.58MHz signal of the oscillator. Now put on your headphones and gradually rotate the volume control clockwise. A hiss should become more evident as the control is advanced. If a loud and raucous noise is evident at even slight rotations of the volume control, look for bad joints around the pot and around Some component leads must be soldered on both sides of the PCB. Commercial boards will have a green solder mask so these joints will be easy to spot. M A Y 1990 71 The wiring connections between the rear panel sockets and the PCB are made via 10-way connector strips. Keep the wiring neat and tidy. open circuits around ICl or IC2. If you have an oscilloscope, it should show a sinewave at the oscillator frequency across the dummy load at about 20V peak to peak and after 10 seconds the dummy load resistors will become quite hot. To fully test and operate the Mozzie you will need at least one other Mozzie or another transceiver set to 3.58MHz in the vicinity. For best results too, an efficient antenna system is absolutely necessary for a QRP (low power) rig such as this. With another transmitter set to 3.58MHz, set trimmer VCl for the desired beat note which can be around 500Hz to lkHz or higher or lower, if you prefer. You should only need to do this once, before the cover is screwed on. Mechanical assembly All the parts on the front panel are soldered directly to the PCB. Route the leads to the connector strip as shown and make sure that all polarised parts are correctly oriented. IC5 or its associated electrolytic capacitors. If all is in order, disconnect the power and proceed to test the transmitter circuit. Transmitter testing With the 470 safety resistor, dummy load and temporary antenna still in place, throw the Tx/Rx control switch down to Tx and temporarily connect a normally open pushbutton switch between K2 and Kl on the Sl connector strip. About 80% of full supply - ie, about + 4.8V - should be present at pin 10 of ICl. About + 3.5V should be present at the K2 ter72 SILICON CHIP minal (anode of D2), indicating that the oscillator is running. If all is in order, it is time to short out the safety resistor and expose the Mozzie to the full awesome power of the four AA cells. An ammeter in series with the supply to the Mozzie and set to 1 amp FSD would be a good idea in the remote event that something is way out of whack in the remaining untested circuitry. Press the pushbutton gingerly several times and check that the ammeter shows a current drain of up to 250mA. Anything significantly more than that indicates shorts or Final assembly of the Mozzie is a matter of fitting the front and rear panel artwork, installing the PC board and sockets in the case, and then completing the wiring. The front decal should stripped off its backing sheet to expose the adhesive layer and carefully manoeuvered so that the circular legends surrounding the controls are centred. Shining a light from behind the panel will greatly assist this alignment. You will only get one crack at this, so take it easy. Now do the same with the rear decal. Run a scalpel or small craft knife through the decal and around the inside of the control shaft holes to remove the surplus paper and adhesive. The Mozzie PCB with standoff pillars fitted now slips into the case with the controls protruding through the front panel. Next, attach the nut to the pot and gently tighten, followed by the collett mounting knob and cap. The mounting pillars can now be secured to the base with the screws provided. The RCA antenna connector is screwed to the rear of the case on the right side, looking from the back. To the left is the 6VDC RCA connector with the centre contact being the positive connection. Install the other sockets and complete the wiring as shown in Fig.2. Do not apply more than 6VDC to the circuit or failure may result.~ ( AT&M J AUSTRALIAN TEST AND MEASUREMENT Pty. Ltd. 28 HOTHAM PARADE ART ARMON NSW P.O. BOX 732, 2064 PHONE 02-9062333 FAX 02-4384219 A1 & 1\I Produce over 30 High Quality Electronic Construction Kits using professional grade components and techniques for industrial applications, education and research. The kits are all developed in our laboratory and include individual instruction and application booklets showing theory of operation , construction method, and testing. Our products are for serious work and can form the basis of many types of electronic equipment and systems. WRITE, PHONE OR FAX FOR O UR CA TALOGUE (2nd. EDITION) ALL PRICES F.O.B ARTARMON ... PLUS 20% SALES TAX IF APPLICABLE. .. FRE/GHT $8.50 PER ORDER A '1 113 Universal 4 Digit 4MHz Counter, bright Orange 1/2" Displays, Reset & Latch SV S0mA ... .. $54.50 ATM27 8 Cha1111el Temperature A TM28 31/2 Digit LED DVM Meter uses "K" Thermo wire pairs for ±199.9mV or 1.999VDC Jumper Se!. -7~C to +350°C Plugs into ATM28 Bright Orange 1/2" Disp. .... $56.00 ..... $85.00 "K"PTFE Clad .... $ 4 .00/M \ ' · I '."l Stopwatch/timer co1111ects to ATM13 1, 1/ 10 or 1/lO0Sec at 9999 counts. Crystal controlled operated by switch, opto beam break (A TM20) ..... $44.50 AT M 2 l 80MHz Dig. Freq. Meter A TM29 Plug in Autoranger for co1111ects to ATM13, 4 ranges CMOS/ ATM28, ±200mV, 2V, 20V, 200VDC TTL input ..... $38 .50 ..... $ 64. 50 t\.Ttvl26 Digital Amphometer (CAR SPEED METER) as per April EA complete W/Sensing Cables, case and connectors. Opto beam hrcak kit ATM20 $33 .00 ea- 2 needed. SPECIAL FOR MAY ..... $130 .00 A T M 17 Digital Storage Adaptor for Oscilloscopes 200 to 200K Samp,/Sec as Per Dec. '89EA .. ...$ 185.00 (Complete W/Case) HWK/ UB7 0 Universal extruded AL Panel Mtg. case w/Bezcls & Filter FOR ALL ABOVE KITS . .... $35 .50 REMOTE CONTROL By BOB YOUNG Aerodynamics & stall conditions In our discussion so far on aerodynamics, we have seen that the formulas for lift and drag follow a square law so that if you travel twice as fast, you generate four times as much force. This causes a lot of problems in airframe design and means that to fly very fast, wings must be small. Because weight follows a relatively linear law, there is much to be gained by increasing the speed. With modern engine technology squeezing more thrust out of less weight and modern engineering and material technology reducing airframe weight, we can arrive at the curious situation where we now have too much wing. We are thus flying so fast and the wing is generating so much lift that we must fly at slight negative angles of attack to get rid of it. This is inefficient as we really need to get the wing working at or near its best lift/drag ratio. The obvious solution here is to reduce the wing area and force the wing to work at a higher angle of attack. Thus we arrive at modern experimental aircraft such as the X-3 which has the tiniest wing imaginable but is designed to fly very fast. The compromise here is always speed against manoeuvrability. The test pilot slated to fly the X-3 was said to have admired the fuselage shape greatly when he first saw it and enquired when the wings were to be fitted. When advised that the stub already fitted was the wing, he was somewhat taken aback. The modern military designer works at this problem in another 74 SILICON CHIP way. He just keeps cramming more and more equipment into the airframe until it is grossly overweight and needs all the wing it can get. Now we come back to the interactive problem again. Just how do you get this thing off the ground at low airspeeds? In some instances, NASA cheates and launches these X-aircraft from a mother ship. It still must be landed however, much to the pilot's concern. How do you get this machine back on the ground safely when lift is falling with the square of the velocity reduction as it slows for landing. This, as any pilot will tell you, is the really crucial question. Very early in the piece, pilots in the US Army-Airforce strongly objected when first introduced to the old Peashooter, the first low wing monoplane fighter introduced into service. They were very perturbed by the extremely high landing speed of this aircraft. The old biplanes used to drift over the fence at 40 to 50 knots whereas the Peashooter roared over at 65 knots. Compare this to the Spitfire (90 knots) and the X-3 (240 knots). Times certainly have changed. Wing loading One of the critical factors in landing speed is wing or surface area loading, which is an expression of EFFECT OF VARIOUS LIFT INCREASING DEVICES ON WING CHARACTERISTICS BASIC AIRFOIL 15° - - 12° 51% 51¾ 'SLOTTED FLAP 12° 53¾ 42¾ FRONT SLOT (AUTOMATIC) 28° 26¾ 35¾ 19• 69¾ 7% 19° 75¾ 10% SPLIT FLAP 14° 70¾ 63¾ ZAP FLAP 13° 85 ¾ 77¾ FOWLER FLAP 15• 90¾ 83 ¾ ' ,.. SIMPLE FLAP FRONT SLOT AND SIMPLE FLAP FRONT SLOT AND SLOTTED FLAP ' \ ' \ '\. ' Fig.1: modern aircraft rely a variety of lift increasing devices so that the aircraft can be brought to a manageable speed for landings. This table shows the effect of some of these devices. the gross weight of the aircraft over the lifting surface area. This is expressed in lbs/sq ft or kg/sq metre. Thus, if we want to fly fast (ie, we reduce the wing area), we suffer some penalties and one of them is increased wing loading and higher landing speeds. Many compromises have been devised to overcome this problem, the most exotic of these being the variable sweep wing (eg, the F-111). This mechanism serves a twofold purpose but the one of interest to us is the increase in wing area (and thus lift) it offers for low speed flight. Model aircraft typically fly with wing loadings between 1.51b and 2lbs per square foot. In a recent survey of full size flying boats, the wing loadings ranged from 30-60lbs per square foot. Modern fighters can run as high as 150lb/sq ft. Variable geometry The other fact of importance, as we have already seen, is CL which can be greatly influenced by the shape of the airfoil and the angle of attack at which the airfoil is presented to the airflow. Thus, by using variable geometry wing sections (flaps, slots etc) and flying slower and thus forcing a higher angle of attack and therefore CL, we can bring the aircraft to a manageable speed and attitude. Fig.1 shows a variety of lift increasing devices and their relative effectiveness. Modern high speed aircraft rely heavily on these devices and on even more modern and exotic systems developed since this chart was prepared. Forcing a higher angle of attack also increases the drag markedly and further slows the aircraft. In this manner we can eventually put it down safely, albeit at a somewhat high speed, for the prime factor is always that V2 law. Small increases of speed give big increasef! in lift. Thus, it is always cheaper and easier to train pilots to land at higher speeds than to squeeze more lift out of linear devices such as airfoils and flaps. Interestingly enough, the power setting which gives the slowest airspeed is maximum power. There are several reasons for this but put briefly the thrust vector becomes an increasingly important lift component, until you reach the VTOL (Harrier) style aircraft. In this case, thrust is the only lift component. This type of aircraft is a special case and breaks all of the rules of flight. The VIFF (vector in forward flight) ability of the Harrier gave the Argentinian pilots quite a headache. Stalling As we saw last month, there is a definite relationship between angle of attack and C1. As the angle of attack is increased, there is a corresponding increase in C1 until the streamlined airflow breaks down into turbulent flow. At this point, the airfoil is said to have stalled and the wing losses nearly all lift and the nose of the aircraft drops. Depending upon the cleverness of the aircraft design and the task it is designed for , this stall can be violent or very gentle. In some cases, the aircraft can fall sideways and spin. Stalls are very dangerous in piloted aircraft and all manner of safety devices have Fig.2: the Boeing P-26 Peashooter was the first monoplane fighter produced for the US Army Air Corps, as well as being the first all-metal production fighter. It first flew in March 1932. been devised and fitted to aircraft over the years. Stall warning hooters can give the nervous passenger quite a fright. Landing is a dangerous time in an aircraft for the art of landing is to fly as slowly and therefore as close to the stall as safely possible. Errors in judgement can have serious consequences. This is particularly so in bad weather. Such factors as wind gusts, wind shear, bad visibility, icing and wind gradient can have very powerful effects on an aircraft. Wind shear The last factor is very important in model flying. Briefly, the viscosity of air results in a slowing of the wind speed as it gets closer to ground level (Fig.3). This effect is more pronounced the closer we approach the surface until within 20cm of the ground the wind speed almost ceases. Full size aircraft experience this to some degree but their wings never get to within centimetres of the ground; those on model aircraft do. As the aircraft settles for landing, sinking deeper and deeper inMAY 1990 75 SURFACE VISCOSITY ~ 77777777777777777777777,, to this wind gradient, lift begins to fall and the model starts to sink more quickly. The pilot pulls back on the stick, increasing angle of attack and drag and further reducing airspeed. The result is a stall or a thumped in landing with possible airframe damage. The moral? Keep some speed in hand for this possibiltynr use throttle instead of elevator to increase lift. I learned long ago to think of an aircraft as a 4-dimensional or 4axis vehicle, with throttle (therefore speed) as the fourth axis for this reason. The final interactive factor we will discuss is the relationship between thrust, drag, lift and the ability of an aircraft to turn very tightly. As we have already discovered, an aircraft requires enormous amounts of thrust to achieve high flight speeds. With drag increasing at the square of velocity, the total drag figure for even a very clean airframe is extraordinarily high but what happens when this aircraft is travelling at low speeds? 76 SILICON CHIP Fig.3: landing can be a dangerous time for model aircraft due to wind shear - an effect whereby the wind speed decreases near ground level This can lead to a sudden reduction in lift so it is important to always lceep some throttle in reserve. Reserve power The result is an enormous amount of excess thrust which can be put to many interesting uses, not the least being take-off. Watch a modern jet airliner blast off the runway and pull up into a steep climb. Because it climbs out at much lower speed than its maximum level flight speed, an airliner has much more thrust to channel into its lift/thrust vector. Compare this to the poor old DC-3 tottering off the same runway. The climb angle is very low because the top speed of the DC-3 is only about twice its take-off speed. There is very little reserve horsepower for climbing. Loss of an engine in a DC-3 was a serious business for reasons already discussed. The situation in a modern jet fighter is even more pronounced and a Mach 2 fighter manouevering at 400 knots has an enormous amount of reserve thrust for use in turning and climbing. The ability of a fighter to turn tightly is a complex issue but is related to the stalling speed of the aircraft which is related to wing loading and thrust, as we have already encountered. The radius of the turn is given by the formula: r = (Vs 2/g)(CL maxlCL) To quote Kermode, "this shows that the radius of turn will be least when: C1 = C1 max ie, when the angle of attack is the stalling angle and the radius of turn equals Vs2/g. It is rather interesting to note that the minimum radius of turn is quite independent of the actual speed during the vertical banks. It is settled only by the stalling speed of the particular aeroplane. Thus, to turn at minimum radius, one must fly at the stalling angle, but any speed may be employed providing the engine power is sufficient to maintain it. In practice, the engine power is the deciding factor in settling the minimum radius of turn whether in a vertical bank or any other bank, and it must be admitted that it is not usually possible to turn on such a small radius as the above formulae would indicate". That was written in 1932. Air has not changed much since then but engine technology certainly has. Kermode then goes on to sum up the turning ability of aircraft: "The formula above applies to some extent to all steep turns and shows that the aeroplane with the lower stalling speed can make a tighter turn than one with a higher stalling speed. But in order to take advantage of this we must be able to stand the g's involved in the steep banks and we must have engine power sufficient to maintain turns at such angles of bank" . Correct balance The ramifications for modellers is that the correct balance of weight, wing section, wing area and power loading is vital for a successful aerobatic model. Underpowered models are very poor performers. Keep in mind here that loops are only a special case of a vertical bank. As stated previously, models do not carry pilots and thus do not need to consider human comfort during manoeuvres. The model designer must however consider the structural forces involved for models can easily pull 10-15 g's. I have seen models snap wings in flight and this is very dangerous for those standing on the ground! Once again however, the central fact is the power required to keep the airspeed constant in spite of the increase in drag brought about by the increase in angle of attack. And again, the scenario described last month of an aircraft falling into the drag bucket during take-off also applies to an aircraft when turning. As the aircraft begins to bank, an increase in the angle of attack is required in order to provide the increased lift which is needed to provide the acceleration towards the centre of the turning circle. This calls for more power. If this power is not available the model will slow down, losing lift and forcing the pilot to increase elevator deflection in an attempt to maintain altitude. This is futile, for the increased angle of attack will only increase drag and cause further reductions in airspeed. The most probable outcome of this situation is a stall and spin into the ground. The stall and spin on final approach was a common cause of crashes in the early days of aviation. Equally dangerous is the stall and spin after loss of power on take off. This is most commonly brought about by pilots turning quickly in an attempt to make the airfield while some altitude remains. Land straight ahead The golden rule in this situation is, if in any doubt, land straight ahead. Without power the nose must be pushed down to maintain speed during a turn and a lot of altitude can be lost, leaving the pilot with a downwind landing on his hands. Runways shrink in length dramatically in this situation and those barbed wire fences at the boundary do awful things to aeroplanes. Fig.4: this diagram shows the forces acting on an airplane during a properly banked turn. The centripetal force is provided by banking the aircraft so that the wings can supply a component towards the centre of the turn. CENTRIPET Al FORCE wv2 time were unsound. I may have landed it straight ahead, only to hit a rock or a treestump hidden in the long grass. That would have been bad luck. From hundreds of yards away it is impossible to see hidden objects. But to stall and spin was bad airmanship. The real issue is that all of these situations call for split second decision making and a sound grasp of the fundamentals involved. Full size aviation schools teach their pupils these badly needed facts of aviation life but the tyro model flyer is rarely taught even a rudimentary knowledge of aerodynamics. The result is more broken models than necessary. Worse still is the loss of valuable but discouraged people from the R/C model movement. The true worth of a pilot is measured in his ability to analyse lbs gr W lbs Power can be lost for any number of reasons, some quite odd. I once crashed a model in the above situation when I lost a blade off my propellor. I made all of the above mistakes and tried to nurse it home on reduced power. The result was a stall and spin. The correct procedure was to throttle back and land straight ahead. In my own defence, I did not know that I had lost a blade at that time and there was one of Charlie Brown's kite eating trees stretching out its limbs directly in front of me, with rough ground underneath. But the fact remains I lost the model and so the decisions I made at the and initiate the correct remedial actions for all in-flight problems. A pilot's ability to land an aircraft under the most trying conditions is paramount to the safety of both himself and his passengers. Beginners seem to feel that aerobatics are the most difficult and rewarding of in-flight activities. Let me state right here and now that aerobatics are easy and unimportant. The most difficult and rewarding manoeuvre is landing that aeroplane safely every time you take off. For this reason landings must be practised continuously and from every possible angle and contingency. ~ MAY1990 77 - - - - · · · -· · · - - JM TVMn cLcv I nu 1~1v0vM 1 vM.n CLCV I nu1'11v..:>vM 1 VMn t: L C. V I nv1'11Vv.Jt'\ TV/-\n t:LC.V I MUl"41VVV,.... f'VMti CLt:.V I HUNIL~AYL.;AH t::LtL; I HUNIC!:iJAYCAH ELECTRONICSJAYCAR ELECTRONICS .J,I I ELECTRONICS JAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICS ~ I ELECTRONICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICS~ I ELECTRONICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS ,,If I ELECTRONICS Y A ECTR NICSJAYCAR EL CTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICS ,,If I ELECl I ELECT I ELECT I ELECT I ELECT I ELEC TF I ELEClf I ELECT The fN,/ Mk 6 is a high fidelity woofer utilising a 25mm I ELECTr I ELECT diameter long throw voice coil wound on an aluminium I ELECT former and a high compliance suspension with a Incorporates a grey polypropylene cone and a square black I ELECT polyurethane foam roll surround, resulting in excellent frame. Suitable for a two or three way system. I ELECT This midrange has a grey polyproJ1(Iene cone which matches. linearity at high power. Impedance 8 ohms I ELECT It has a square black frame and is a totally sealed unit Power Handling 65 watts rms I ELECTI Resonant Freq. 49Hz Impedance 8 ohms Resonant Freq. 39.5Hz I ELECT SPL 95d8/1w/05m Resonant Freq. 700Hz I ELECT Freq. range 39.5Hz - 5khz Power Handling 50 watts rms I ELECT Freq. Response 700 - 13kHz Sensitivity 96d8/1w/1 mt Freq. Response 50 6kHz I ELECT Power Handling BO watts rms system Voice Coil Dia. 25mm Oms 1.73 I ELECT SPL 91dB OMS 2.317753 Oes 0.52 I ELECT Cat. CM-2083 OES 0.5470474 I ELEC T Oto 0.4 OTS 0.4425861 I ELECT Vas 22.2 VAS 3.241097 I ELECT Vented Enclosure I ELECT Cat CW-2109 20Iitre Volume I ELECTI fb 52Hz I ELECTI 53Hz f3 I ELECT Vent Length 69mm I ELECT I ELECT Vent Diameter 50mm I ELECT Cat. 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NA-1008 I\R ELE:CTF I\R ELEClF I\R ELECTF I\RELECTF I\R ELECTF I\R ELECTF Cat NA-1004 I\R ELECTF I\R ELECTF I\R ELECTF I\R ELECTF I\R ELECTF ndard model I\R ELECTF t XC-0100 I\R ELECTF I\R ELECTF I\R ELECTF I\R ELl;CTF I\R ELECTF I\R ELECTF I\R ELECTF I\R ELECTF I\R ELECT, \R ELECTr \R ELECTF \R ELECTF \A ELECTF \R ELECH \A ELECH \R ELECTF CTRONIC: "'""'""'""'""""""""""""""""""'"""'"""'"""""""""""""""""""""""""""""'""""""'' ===,...,;c;-: TRON!( CTRONIC: liiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiilliliiiililiiiililiiiililiiiililiiiililiiiililiiiililiiiiiiiiiliiiiiliiiiiliiiiiliiiiiliiiiiliiiiiliiiiiliiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii liliiiiiiiiiliiiiiliiiiilliiiliiiiilililiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiill TRONIC CTRONICSJA YCAR ELECTRONICSJAYCAR JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJA YCAR ELECiRONiCSJAYCAR ELECTRONiCSJA YCAR ELECTRONIC CTRONICSJA YCAR ELECTRONICSJAYCAR JAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICS.JA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONIC CTRONICSJAYCAR ELECTRONICSJAYCAR JAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELE CTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRON I( CTRONICSJAYCAR ELECTRONICSJAYCAR JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONIC 0 "Spy in the Sky" Sensor ·-- s1 •9 5 L ?= Philips BSRS2 Darlington Transistor s19.95 25~ ea ''Rapid" Solderless Connectors Freezer Circuit Spray Board Cleaner $9 Cleaning s&.95 Solvent 1 oldering eavy D tripper/ rimper 12V Lightweight Soldering Iron s11.so $6.95 ck Move 12.95 :,::~======- •= =============•::::,:;: :AR :AR :AR :AR ;AR ELEcio~ic&JA~CA; ELECTRONiCSJAYCAR ELECTRONiCSJAYCAR El ~ ELECTRONICSJAYCAR ELECTRONICSJAYCAR EL ELECTRONI CSJAYCAR ELECTRONICSJAYCAR ELt ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELE, ELfr.TRONlr.S.JAYr.AR FJ FCTRONIC&JAYCAR ELEt ·· ·oNiCSJAYCAR ELECTRONiCSJAYCAR ELECTRONiCSJAYCAR ELECffioNiCSJAYCAR ELECTRONiCSJAYCAR ELECTAONics fRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS ELECTTlONICSJAYCAf RONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS ELECTRONICSJAYCAI lONICSJAYCAR ELECTRONICSJAYCAR ELECTRON ICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS ELECTRONICSJAYCAI ONIC'-<;.IAYCAR FI FCTRONICSJAYCAR FI Fr.TRONlr.S.IAYr.AR FI Fr.TRONIC'_<;.IAYC'.AR FI Fr.TRONIC'-<:.. JAYr.AR FI Fr.TR/"\Nlr~ c, crTO"'"".:SJAYCAI ::=:::,,..... · · · .. · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·· · · · · · · · · · · · · ... · · . · · · · · ····..·.::::::::::::=··--•'• '• '•'•'•'•'•'•'•'•W,', ···,',',···················· ···· · ,. ························· ······ ···· ·····,. ········.. ·· ··· ·············· ··· ·············· ·············... ................ ·. ·.·· ··,··=::::: 1 ELECTR ·t Deluxe Black Rack Boxes Reduced ( Frequency . Counter DMM A with capacitance meter, logic probe and diooe 255 78 853 98 429 62 429 95 tester. lOAmp. Cat QM-1400 $99.95 20 Range Cat QM-1410 •49.95 C D E 177 208 208 292 305 75 401 100 $39.50 $49.50 481 69 481 100 $49.50 $65.00 Normally 429 122 292 481 126 $75.00 st 3 units are rack mount 19' r full details on all these products see our 1900 catalogue. }D'==·====== DMM 8 ' . * • ·, ·= •• : May only $29.50 $ 3 4 .50 $34.50 $49.00 $55.00 : : • : • • : 1 - -A - - - - i f .(r2_/2 i D~ I : I / .....·.w.·.·.·.· ... ·.· ...·.·.·.·.-.·.·.·.·.·.·.·.·.w.·.·.·.·.·.w.·.·.w.·.·.w.·.·.•.. :':''( ..·-,::::: 16 \ • : Drawer Parts . Cabinet ii:::'.:·.,•.. , Digital Capacitance Meter : ·: • , Cat HB-6320 s12 • 95 200pf to 20,000uf . . 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I ! ! ~~~g~~ Cat AA-0330 Still available at s999 m!~~ ELECTR May Only $3.95 r·vifa Speaker Kits 1 ELECTR 1 ELECTR 1 ELECTR 1 ELFCTR 1 El fCTR 1 ELECTR 1 ELECTR 1 ELECTR 1 ELECTR 1 ELECTR 1 ELECTR 1 ELECTR 1 ELECTR 1 ELECTR 1 ELECTR 1 ELECTR ELECTR 1 ELECTR 1 ELECTR 1 ELECTR 1 ELECTR ELECTR HFCTR ,ELfCTR ELECTR ELECTR ELECTR 1 ELECTR 1 ELECTR ·.·· ~ ~~g~ ·== = Power · Normally •s.95 ~t~g~ •• 1 ELECTR •· : ~t~g~ • 1 ELECTR ·• : ~~~g~ • 1 ELECTR • 1 ELECTR _.J_g:g~:: l!I! . ELECTRONII f-l ECTRONII fLECTRONII ELECTRONII COMPUTER BITS By JENNIFER BONNITCHA What to do when your computer goes bung You've tried everything you can think of but your computer won't cooperate. It just sits there defiantly, seemingly gloating at your lack of knowledge. This is the first in a series of articles that will give you the whip hand. Not so long ago - at least it seems that way - when personal computers were still a glint in the designers' eyes, most people who had anything to do with computing worked on mainframes and mainframe terminals. The disadvantages have been well documented and need not be related now (although it is interesting to note the "flavour of the month" treatment networking currently enjoys). One of the main advantages of early computing for the average computer user was the computer terminal. When all functioned correctly, work progressed at a frantic pace and nobody worried too much about maintenance, backups, etc since "they" took care of the more mundane activities. "They" of course, were the computer room staff - a mythical, almost mystical group who moved around a company with a certain air of distraction as befits those who aspire to greatness. Whenever a problem arose, the first step was to check whether cries of anguish could be heard emanating from other terminals close by. By listening to the level of sobbing, you could easily tell how long it had been since a "save" 82 SILICON CHIP command had been issued on hours of precious work. However, sometimes you were all alone - everyone else just kept on tapping away. "So what's the problem?" you would ask. "Why me? What have I done to deserve this?" Are the computer operators playing a trick on me just because I beat the senior shift operator to the last drop of the milk this morning? There are certainly times when, even with the best will in the world and the combined efforts of a multitude of prevention procedures, things just don't work. That darned computer, screen, printer, etc just won't do what it's supposed to do. So problem determination seems to be the order of the day. You check to see whether the thing has any life in it at all. When nothing seems to work, you take the only alternative left to you: you call the computer room or information services or the computer support group (call it what it like) and let "them" figure it out. After all, that's what they are paid for isn't it?! Once upon a time, computing really was this simple. You could pass the buck reliably to at least one other person - maybe even a whole department! If the terminal didn't come back to life, you either amused yourself with other work or found another vacant terminal (good luck) until yours was fixed. Sometimes an even more ethereal being, the Customer Service Engineer, arrived armed with a bulging case full of the latest technology to work on your errant terminal. With luck all would be well within a matter of minutes/ hours. Personal computing Today, things are quite different for a large number of computer users. Often, the person in a small business charged with the responsibility of operating a personal computer is the only one who has the slightest idea of what is going on. What happens when a problem arises? This article and several following seek to provide a guide for just such a user. The series will examine all kinds of disasters, from the humble cup of coffee in the keyboard (white with two thanks), through discs folded in half by the friendly staff at the post office (remember how you were strongly advised to use a disc mailer?), to hard disc failures and printer problems (it's just printing rows and rows of garbage). There will also be some software tips, just for a change. Many of the points raised will be quite obvious. However, that is only true when you have experienced a particular problem yourself and discovered the solution. education and training. Technical support and "Help Line" operators could write a book about the problems they encounter from distressed souls out there in user land. Particularly frustrating is the appalling lack of knowledge on even the simple points. What kind of computer do you use? Does it have a hard disc? Do you have a dot matrix or laser printer? Are you using high density or low density discs? Is your printer parallel or serial? Software manuals, as we all know, frequently leave a lot to the imagination. With experience you know that, for example, most word processing programs automatically generate a carriage return at the end of every line. I know that and you know that, but the user new to word processing hasn't the faintest idea what this feature is, let alone how to look it up in the reference manual. The same often applies to computer hardware. That which seems obvious is only so with the benefit of prior knowledge. A true story There's nothing more frustrating than a computer system that's misbehaving. Our series will explore computer problems primarily from a hardware angle but will also cover some operating system problems as well. In the "real world", I spend my time training company staff to use computer software packages. These people range from the absolute beginner who doesn't realise the difference between the letter "O" and the number "O" , right through to those users who are very experienced with a particular program. One of the most difficult points to remember is that the absolute beginner has no idea as to what is going on. An experienced user knows that the DEL and DELETE, ENTER and RETURN, and PAGE UP and PGUP keys each perform identically but the new user doesn't have the luxury of this prior knowledge. To this type of computer user, a 101-key enhanced keyboard corn- plete with 12 function keys, numeric keypad and separate cursor control area represents an enormous challenge. Added to this is the difference in operation of the DELETE and BACKSPACE keys and the rather surprising features of the CAPS LOCK and SHIFT keys (what do you mean there isn't a SHIFT LOCK key, how do you stop the capitals?). Everyone has heard the old chestnut about the computer user who was asked to send a copy of a disc causing some distress. In due course, a photocopy of the offending disc was delivered by Australia Post! Although this seems too laughable to be true, it has happenecl and for a very good reason - lack of Once, a long, long time ago, I was a humble network liaison officer for a computer room at the centre of the Earth. Actually, the computer room was in the basement of a large building - it just seemed like the centre of the Earth! This position involved all kinds of interesting work on the retail point of sale system for a large department store. One aspect of the job was the weekly "on-call" rotation of liaison officers. Whenever the network control boys encountered a problem they couldn't deal with in a store, the liaison officer was beeped and asked to call and hopefully sort out the problem. One Saturday morning, it was my turn. Funny, that doesn't sound like the usual alarm. Oh, the beeper is going off its head. I got up, called network control, found out the problem, made a cup of coffee and rang the offending store. Didn't they realise that at 7.00am on a Saturday real people were still sleeping? The store operator was in conMAY 1990 83 organisation. This is fine in theory and the people who received the formal training can usually show their colleagues what they need to The basic workings of the IBM PC Inside the IBM PC, by Peter Norton. Revised edition. Published 1986 by Brady Books, New York. soft covers, 235 x 188mm, 386 pages. ISBN 0-89303-583-1. If you want a good introductory text on the IBM PC family of computers, this has to be one of the best books around. The author is Peter Norton who created the famed Norton utilities software package, so he really knows what he is talking about. The book covers some of the hardware aspects, the disc operating system and describes siderable distress since the in-store controller (a minicomputer of dubious intelligence) wasn't working as it should. No matter what, it wouldn't display the correct date and time. Not a problem, I thought. There's plenty of time until the store opens at 8.00am and the start-up procedure usually takes only 5-10 minutes. OK, let's go through the procedure slowly - me first, then you. At the end, all seemed to function as it should but the store operator insisted that all was not right. We went through the procedure again and the situation started to get a little tense. Opening time was fast approaching and if we cou~dn't resolve the problem, the store would have to start implementing a different operating procedure. Then it came to me in a blinding (and most welcome) flash of inspiration. At what seemed like the eleventh hour (in hindsight it probably wasn't so desperate but you know what it's like when the pressure is on), I remembered my last visit to the store. Attached to the minicomputer was a small magnetic clock which the operators used for checking the date and time. Today's operator only worked Thursday nights and Saturday mornings. Casually, I asked whether the date and time were correct on the 84 SILICON CHIP know. the built BIOS (Basic Input/Output System). A full review appeared in the February 1 990 issue of SILICON CHIP. printed report produced by the computer. The affirmative answer confirmed my diagnosis - the battery had run down in the digital clock! I explained to a very relieved operator that the clock was not, in fact, a part of the minicomputer. It was there only for convenience and yes, the morning's procedures could continue as usual. We all had a good laugh about it on the following Monday but it emphasised a very important point. Never assume anything. Even if you think that the situation is under control, check again. The store operator worked only in one store. The computer centre people had the benefit of exposure to equipment in different stores and so knew that the digital clock had no connection with the in-store computer. But how was the store operator supposed to know that? The answer, of course, is education. Problem solving Problem determination is one half of the battle. Satisfactory resolution is the other. One of my pet dislikes is the practice some companies adopt in a misguided effort to keep costs down. Often, one or two staff members are sent on a training course. The idea is that they will then impart their knowledge to others in their What they are often not good at is explaining why a certain procedure functions as it does. They are also usually unable to explain why varying a series of steps gives an entirely different result to that obtained previously. Or why a problem has cropped up when the procedure has been carried out errorfree many times before. By the end of this series, computing will present less problems and provide more answers. One of the interesting things about computing is that the more you know, the more you realise you don't know. You attend a DOS introduction course to learn all about the operating system. At the conclusion, you know how to format a floppy disc as either a data or a system disc and you know the difference between them. However, you may not fully realise just what formatting actually does to the disc. You should also know how to run CHKDSK to determine, among other things, how much standard memory your computer has on board. But what about extended memory? How can you find out whether your computer has any and if so, how much? Sure you can interpret the basic results of CHKDSK but what is "Lost Clusters Found in N Chains" or "File x Cross-Linked on Cluster N" ? That's pretty heavy stuff. So you purchase one of the excellent " tell me more" books like The Paul Mace Guide to Data Recovery or one of Peter Norton's books: Peter Norton's DOS Guide, Inside the IBM PC or Inside the Norton Utilities. As I said, the more you know, the more you realise you don't know. The coming series will seek to explore day-to-day problems primarily from a hardware angle. However, some operating system problems will creep in simply because the two sometimes can't easily be separated. Sit back, arm yourself with something cold and enjoy your trip to the restaurant at the end of the universe. ~ UPER AVINGS AT HERIDAN'S BLACKTOWN (02) 621 1494 SHOP 30, PATRICK STREET, CENTRAL PLAZA SENSATIONAL SPEAKER SALE 15" WOOFER 120 WATTS RMS, 200W MAX 12" WOOFER 100 WATTS RMS, 150W MAX 10" WOOFER 60 WATTS RMS, 1 00W MAX 8" WOOFER 60 WATTS RMS, 1 00W MAX 6½" WOOFER/MIDRANGE 30 WATTS RMS, 50W MAX $99.00 $49.00 $38.00 UPTO TWO SPEED CORDLESS DRILL & SCREWDRIVER ~~~ i SOLDERING IRON STANDS *LARGE METAL BASE *SPONGE PAD FOR CLEANING TIPS REDUCED TO $9.95 COMPUTER/VIDEO JOYSTICK * DUAL FIRE BUTTONS * RAPID FIRE BUTTON *SUCTION FEET 3.5" & 5.25" DISC DRIVE CLEANERS $5.50 ea *USE UP TO 15 TIMES * NON ABRASIVE DISC *CONTAINS SAFE CLEANING FLUID CAPACITORS only $4.50 ea SCOOP BUY $1.95 ea GENUINE TELECOM DOUBLE ADAPTOR ONLY WHILE STOCK LASTS STATIC RAMS 2114 $1.00ea 4116$1.70 6116-1 $4.50 6264 $6.00ea 62256-80 $19.95 SONIC ' D' NICAD FOR ATARI OR COMMODORE COMPUTERS only $24.95 NEXT TO HOUSING COMMISSION PLENTY OF PARKING AND CLOSE TO RAILWAY STATION SAVE $60.00 10,000µf 40 VOLT 22,000µf 25 VOLT SAVE$19.95 MAIL ORDERS TO: SHOP 30, PATRICK STREET CENTRAL PLAZA, BLACKTOWN NSW 2148 $239.00 $22.00 $30.00 $65.00 *12-MEMORY MESSAGE RECORDING * TOUCH-UTE DIALING $89.00 SAVE *POWERFUL 4.8 VOLT MOTOR-~ * TWO SPEED - 325 & 150 RPM · *PILOT LAMP * 1 2 MONTH GUARANTEE PANASONIC ANSWERING MACHINE with REMOTE CONTROL Mail Charges: $15-$19.95 . . . ..... . .... $5 $20·$39.95 .. . ..... ... .. $7 $40-$69 .. . .. . . . . ...... $8 $70-$99 .... .. . .... ... $10 $100 and over ......... $15 Larye or overweight articles sent Skyroad Freight Forward. DRAMS 4 164-1 5 $2.00ea 41 2 56-1 2 $6.00ea 41464-1 $7 .00ea 4 Amp 1.2V Top Brand Battery 10% OFF OUR ALREADY CHEAP RANGE OF ANTENNAS $22.00 pair BUT BE QUICK Trading Hours: Mon-Wed, Frl ...... 9am-5.30pm Thurs ... ... .. . .... 9am-8pm Sat ................. 9am•3pm VISA t----------'--------NOTE: We accept Ban kcard, Mastercard and Visa. However, we cannot give quantity discounts on credit card purchasers or accoun t orders. Minimum for account orders is $15 exclusive of postage and packing. Alf prices include Sales Tax. Alf prices quoted are for this month only or until stocks last. IPRODUCT SHOWCASE I 0.1 V/div on channels 3 and 4. All four have a 150MHz bandwidth with a rise time of 2.3ns. Maximum input voltage is 400V (DC + AC peak). A signal delay line allows leading edge and single shot triggering. The triggering itself has a variable hold off for viewing complex waveforms. The unit is supplied with an operator's manual (which includes circuits) and a 2-year parts and labour warranty. For further information, contact IRH Components, 32 Parramatta Road, Lidcombe, NSW 2141. Phone (02} 648 5455. Semi-automatic car antenna Hitachi 150MHz CRT readout CRO While this top-of-the-line Hitachi V-1150 oscilloscope has been around for a year or so, it is still an instrument of considerable capability. In addition to the 4-trace display, the unit also includes a 150MHz frequency meter with 5-digit display and O. lHz resolution, and a digital voltmeter which can measure AC volts, relative [with a dB reading) and DC volts. In fact, the V-1150 is a very fine AC/DC millivoltmeter with resolution and accuracy that would cost thousands of dollars as a single purpose instrument. As well as the normal on-screen information such as timebase setting, delay and channel sensitivity, two lines of 30 characters allow user defined comments to be added such as waveform description and dating for future reference. Input sensitivity is a maximum of 2mV/div on channels 1 and 2 and Quartz guitar tuner from Arista Trying to tune a guitar by ear is often difficult but this new quartz guitar tuner takes away the guesswork. It will tune a large range of string instruments from electric bass guitars to violins. The unit is battery operated and has input and output sockets to allow you to plug in your guitar tuner and feed the tuner output to an amplifier. In use, you simply plug the guitar lead into the input or place the guitar near the tuner's in-built microphone. Then, using 86 SILICON CHIP the up/down button, you switch to the desired note and start tuning the strings. The meter will show whether the string is sharp or flat. The unit comes with an instruction sheet and is available from Arista Electronics outlets for $74.95. Sick of having to get out of the car and raise your old antenna? Then this will be well worth looking at. Operating from 12 volts, it has five sections with a total length of 1 metre at full extension. Installation instructions are provided on the back of the pack. The unit is operated via a centre-off switch mounted inside the car. It is available for $29.95 from any Dick Smith Electronics store [Cat.A-7360}. 50-piece screwdriver set This set contains 50 of the most common driver bits and sockets you may need. It has a single bidirectional ratchet driver with a magnetic bit holder, seven Torx bits, nine hex bits, three square bits, two Posidrive bits, three Philips bits and four flat-head bits. Also, there are 18 sockets ranging from star-types to hex types between 6mm & 12mm, and imperial sizes from 3/16-inch to 1/2-inch. The whole set comes in a black metal case with a plastic liner. For only $29.95, there's little reason not to have one for the car and the workshop. It comes in a hinged metal case and is available from any Jaycar Electronics store. Novel 1.5V battery testers emory to ata holdt iode and isplay easurements · 4 1/2 digit large LCD display Measures capacitance 200kHz frequency counter Diode and Transistor testing ,.......,...,_ , ' ._ ,, . ~ ·· . ,.... .. -~ ~- 3 1/2/digit large LCD display Measures capacitance Measures Temperature -20 to +15(l'C Do you have a drawer full of 1.5 cells sitting around because they're not flat enough to throw away yet? Or are they sitting in the drawer having a rest? It doesn't work you know. Even new batteries discharge themselves over a period of time and become flat. You can't effectively test cells and batteries with a multimeter because multimeters have high input impedances and so don't present any load; ie, they draw negligible current. These battery testers from Jaycar provide a novel and effective alternative. They consist of a plastic strip with a conductive track on one side. You simply bend the tester around the battery so that the terminals touch the conductive spots on the reverse side of the tester. The front side will glow, showing you how good the battery really is under a load. They are designed for 1.5V cells only and come in a range of interesting designs. At a price of 65c each or 4 for $2, there's no excuse not to clean out that drawer! They are available from all Jaycar Electronics stores. 3 1/2 digit LCD display Memory mode tor relative measurements Data hold function Slim,compact construction You've Gotta Getta Goldstar from: A.C.T. John Pope Electrical 80 6576 N.S.W. D.G.E. Systems (049) 69 1625 e W.F.Dixon (049) 69 5177 e Macelec (042) 29 1455 • Newtek (042) 27 1620 • Novacastrian Electronic Supply (049) 62 1358 e Obiat Ply Ltd 698 4776 e Digitel 709 6511 e Geott Wood 427 1676 N.TERRITORY J Blackwood (089) 84 4255, 52 1788 e Thew & Mccann (089) 84 4999 QUEENSLAND St Lucia Electronics 252 7466 e B.AS. Audiotronics 844 7566 • The Electronics Shop (075) 32 3632 • Solex (Townsville)(077) 72 4466 • Xanthos Electrical (079) 27 8952 $.AUSTRALIA Force Electronics (08) 212 5505 VICTORIA G.B. Telespares 328 4301 • The Electronic Components Shop 670 6474 • .Factory Controls (052) 78 8222 • Mektronics 587 3888 • Truscott Electronics 723 3094 W AUSTRALIA Atkins Carlyle 481 1233 e Leda Electronics 361 7821 PAPUA NEW GUINEA TE (P.N.G.) Pt Moresby 25 6322 Lae 42 6246 Bench-style autoranging DMM Are you sick of craning your neck when trying to read your digital multimeter? This new unit from Arista might be the answer. It's the Arista DMM-5, a miniature benchstyle digital multimeter with the LCD readout conveniently angled for easy reading. It measures transistor hFE, DC and AC volts, current and resistance, as well as having diode and continuity check ranges and a datahold feature. Accuracy on DC voltage is ± 0.8 % on the four ranges from 2 to 1000V and ± 1 % on the four AC ranges from 2V to 700V. The input impedance for both AC and DC voltages is approximately lOMO. Both DC and AC current is manually selected from one of three ranges between 20mA and 10A with accuracies of 1.2% for DC and 1.5% for AC currents respectively. There are six ranges for resistance which are automatically selected from 2000 to 20MO with accuracies of ± 2.0% for the 20MO range and ± 1.0% on the lower five ranges. As you can see from the above, the DMM-5 offers all the normal features but in a different shaped case. Be warned though: some people hate its appearance. Priced at $129.95, the DMM-5 is available from Arista Electronics outlets. 1Mb erasable CMOS PROM National Semiconductor's 27C1024 high speed 1024K UV erasable EPROM is now available from IRH Components. It's designed PCB PO WER TR ANSFORMERS Proudly manufactured in Australia by HARBUCH ELECTRONICS Pty Ltd 90 George St. , HORNSBY, N.S.W., 2077 Phone (02)476-5854, Fax (02)476-3231 to operate from a single + 5 volt supply with a ± 10% tolerance. The 40-pin DIL package has a transparent lid for UV exposure to erase the current bit pattern. Other features include an access time of 90ns, an active power dissipation of 275mW and a standby power consumption of 550µW. It has TTL/CMOS compatible input/outputs, uses static operations (requiring no clocks) and is performance compatible with 16 and 32-bit microprocessors. For further information, contact IRH Components, 32 Parramatta Road, Lidcombe, NSW 2141. Phone (02) 648 5455. Uninterruptable 500W power supply How many times have you lost important files just at the wrong moment because of a blackout or even a temporary glitch in the mains AC supply? This uninterrupta ble power supply from Arista should solve your problem. It provides protection against blackouts, voltage fluctua- 200W car stereo power amplifier If your car stereo doesn't have enough grunt to get you th rough the day then try this 200W power amplifier from Arist.a. It's rated at 100W per channel and can be hooked up as a 200W bridge amplifier. It has a mono/stereo switch as well as a normal/bridge mode switch. Inbuilt overload protection is included as well as a soft start system to protect the speakers from switch-on thumps. The unit comes complete with connecting leads and is available from Arista Electronics dealers. The price? $199.95. That's one dollar per watt. tions, surges, spikes and line noise. If the AC mains voltage varies above or below an acceptable level, the unit switches into the backup mode. This backup mode provides 10 minutes [with a 500W load) of power so you can finish your work and shut down. The power is supplied by an inverter driven by four 6V sealed-lead-acid batteries. These are charged up when the unit is operating normally from 240VAC. Charging time for the batteries is around 10 to 12 hours. The typical transfer time from mains to battery power is 4ms (8ms maximum) and the line regulation while on battery operation is ± 5%. In normal operation, the output AC voltage has the same waveform as the input, but in battery operation, the unit switches to the inverter, whose waveform is a quasisquarewave. The front panel of the power supply provides visual indication of normal and battery operation as well as overload indication. When the unit switches from normal to battery operation, the changeover D.DAUNER ELECTRONIC COMPONENTS WE STOCK A WIDE RANGE OF ELECTRONIC PARTS for • \ \ . '.;,~:"j;_~~-- .:- , WHILE STOCKS LAST Quartz filter 10.9MHz 6kHz BW $12.50 US Filter capac itor 4µF 3kV. $15.00 Electromagnetic Airpump for Aquarium .. $9.00 Timer Motor 240VAC 6RPH . . . . $6.00 is indicated by an alarm beeping, which can be turned off by the "alarm silence" switch on the front panel. If the load connected to the unit exceeds 500W, it will shut down and emit a continuous alarm tone. The unit is fairly heavy at 20.5kgs and once it is in place, you won't want to take it out again! The price of the unit is $1799 and it is available from Arista Electronics Pty Ltd, PO Box 191 , Lidcombe, NSW 2141. ANTRIM Development • Repair • Radio Amateur • Industrial Electronic • Analog and Digital Come and see. Showroom: 51 Georges Crescent, Georges Hall, NSW 2198 (Behind Caltex Service Station In Blrdwood Road) Phone 724 6982 TRADING HOURS: Monday to Friday 9.00 a.m. to 4.00 p.m. Saturday from 9.00 a.m. to 12.00 noon. General Construction TOROIDAL TRANSFORMERS OU TER WINDING WINDING INSULAT 0 1'. - QUALITY TOROIDAL POWER TRANSFORMERS, MANUFACTURED IN U.K. NOW AVAILABLE EX-STOCK AT REALISTIC PRICES. IN NER WI NDING = -~=1---li:11111 -CORF. INSULATI O N KIT SELECTION GUIDE PROJECT I SOW MOSFET Amplifier MOSFET Power Amplifier MAGAZINE ETI Mar 82 EA Oct 85 AEM6000 MOSFET Amplifier (2 reqd) AEM Sep 86 ( I reqd ) I OOW Power Amplifier Studio 200 Amplifier 120W MOSFET Amplifier Power Amplifier, bipolar, 50/80W alternate, I 00/ I SOW Pro Series One Amplifier (2 TX reqd) SC Dec 87 SC SC EA Nov 88 Jan 89 Feb 88 EA Dec 89 ANTRIM TOROID PRICE 35+35V 45+45V So+S0V 30+30V 3o+30V 35 +35V 35+35V 3o+30V 35+35V 45+45V 62.00 7'2.80 VK Powermate MKI I n.so VK Powermaster I 2/ 230V 40W Inverter 12/240V I SW Inverter G2018 H:!025 H2033 D201 7 F20I7 H2018 11 2018 E2017 G2018 G2025 225VA 300VA J00VA BOV A I60VA 300VA J00VA J20VA 225 VA 225VA Code: SC Silicon Chip, EA Electronics Australia , ETI Electronics Today International AEM Australian Electronics Monthly 41.75 55.70 72.80 72.80 44.95 · 62.00 6:.oo PROJECT MAGAZINE EA Dec 83 alternate Powerm ate II VK Powerrnate 25 ( 2 T X required) alternate Charger for sealed lead ac id batteries Dual track ing power supp ly EA Mar 8 4 EA Aug 85 EA Apr 87 EA Oct 88 EA Jan 90 SC SC \far 90 Ap r 90 ANTRIM TOROID E20I4 \8+J8V F20I4 !8+\8V I8+I8V 11 2014 9+9V C201 l 9+9V 8 20 11 E :!0I4 I8+I8V I 8+ I8V 11:014 AT 96 3 :ic I6. SV E20I4 I 8+!8V H20:!6 4o+40V 120VA 160VA J00VA SOVA JOYA \'.!OVA 300VA 6:!SVA 120VA 300VA PRICE 44.95 55 ,70 EBO 38.50 36.00 44.95 72.80 I :!8.78 44.95 72.80 All prices qu oted are I off re tail prices including sales ta:ic bu1 excluding freight. Enquiries from resellers and OEMs welcome. Quantity prices and data sheets available on request. Distributed in Australia by Harbuch Electronics Pty Ltd, 90 George St., HORNSBY, NSW, 2077 Phone (02)476-5854 Fax (02)476-3231 MAY 1990 89 Ill u ~> AUSTRALIA'S CHEAPEST DISKS ! FAX SWITCH 2 0 c:: 1- td ..I I.II ~ 2 ~ Q 0 c:: "NO BRAND" DISKS Now you can buy absolute top quality disks that are also the chalpe ■ I In Au1trall1 ! They even come with a lllellme w1rr1nty, which Indicates the quality of these disks. So why p ■ y 2·3 times the price for the ■-me quality? Pack ■ of 10, DIS DID without boxes, or brand name, just their whllepaper jecket, and Index label. (5 114" disks includes write protects) (ALL PRICES PER 10 DISKS) 1-9 10+ 50+ 5 1/4" DS/DD.$5. 25 $4.95 100+ $4.85 $4.75 5 1/4" DS/H D.$14.95 $12 .95 $11.95 $9.90 1-9 10+ 50+ 100+ • lets you connect a normal telephone handset and a fax to the same telephone line • Detects whether an Incoming call Is for the phone or the fax and automatlcally puts It through to the correct unit • ·11 automatlcally switches when you pick up the phone or use the tex to make an out going call • Lets you override the automatic switching and connect the line to either the phone or the fax as you w ish • It Is protected against llghtnlng strikes- your fax switch has bullt In protection against power surges, created by lightning striking telephone lines. X1ggJ ---$?00"'""" IBM*CARDS G7CGA/ MGP X18007 .... ................... $95 3 1/2" DS/DD.$12.50 $11.95 $10.95 $9.90 MGP X18003 ........... .......... .. $89 3 1/2" DS/HD.$34.50 $32.50 $31.50 $29.9 HEGA X18070 ..................... $169 PRINTERS POWER SUPPLIES LX-400............................$379 LQ-400............................$595 LX-850............................$495 LQ-850............................$995 LQ-1050.......................$1,295 VGA 256K X18071 ..................... $299 VGA 512k X18072 .....................$399 RS232 X18026 ..... ... ............... $39 RS232 & Clock X18028 ....................... $49 FOR OTHER EPSON PAINTERS PLEASE CALL ron BEST PRICES II 8087CHIPS GENUINE INTEL CHIPS (4.TTMHZ) (8MHZ) (10MHZ) (6MHZ) (8MHZ) (10MHZ) (16MHZ) (20MHZ) (25MHZ) 8087-3 8087-2 8087•1 80287-6 80287-8 80287•10 80387•16 8038720 80387•25 $175 $265 $395 $295 $395 $495 $795 $895 $1 ,095 150W SWITCH MODE POWER SUPPLY FOR IBM* PC/ XT* & COMPATIBLES CL AYTON MAI L ORDER 56 Renver Rd , Phone: (03) 543 7877 Fax: (03) 543 2648 E ,.l'IOfltS & OMMISI0 NS E XC EPTED xr·. IBM'. PC' , AT" . are registered trademarks of 1nterna11ona1 Business Machine s. Apple" 1s s registered trademark ol Apple corpoa11on Fe ■ tures selectable "spring centring " or "free floating". Electrical trim adjustments on both axis. 360 degree cursor control C14205 .................. $39.95 APPLE* COMPATIBLt: Ideal tor games or word processing. Fits most 6502 " compatible" computers. C14200 .. .. ....... ....... $39.95 APPLE' IIE & IIC SERIES COMPATIBLE These joysticks h ■ v• adaptor connectors to suit the Apple II , lie, lie and II+ computers. Features include selectable " spring centring" or "free floating" . Electrical trim adjustments on both axi s, 360· cursor control 8nd dual fire button ■ . C14201 ........... ....... $39.95 D RITRON MULTISYNC VGA COLOUR MONITOR Quality Auto VGA, EGA, CGA monitor without the e:w.cesslve price tag! Display Tube: 14 Inch 90° dellecllon P22 Non11lare, tint. 0.13mm dot pitch Active Display Area :245 x185mlT Resolution : 800 dots(H) x 600 ltnes(V) Display Colour: TTL Input: 8116164 colours Analog Input: unlimited colours IBM* X * 640K RAM TURBO COMPATIBLE COMPUTER Check th... features and our prices. We're sure you'll aethey're exceptional value for money! • Final 8Hembllng and teallng In Australia! • Fast TURBO Motherboard • AT* styla keyboard • Tested by ua for 24 hours prior to delivery! • 8 Slot mothertloard • 12 month• wananty! • 150W supply po_, 640K RAM TURBO COMPATIBLE COMPUTER 2 x 360K Disk Drlvn, Multi• function Card, Colour Graphics, Disk Controller, 1 Serial, Par■ llel Port (Clock) ........................$895 WITH 20 MIBYTE HARD DISK: & single 360K Dl1k Drive .. $1,195 & dual 360K Disk Drtves ... S1 ,m WITH 40 MIBYTE HARD DISK: & ■ Ingle 360K V.C. H.D... ,.. $1 ,575 & dual 360K V.C. H.D .........$1 ,725 X14528 .....................$895 Printer X18017.'. ..................... $29 Games X18019 ..................... ..$29 Multi-function X18040 .......................$99 DC OUTPUT : · +5 I 13A • . 5v IQ.SA + 12V/ 4.5 · 12VI 0.5A Multi 1/0 X18045 .... ................... $99 X11096 ...... ... ..... $129 2 M/Byte Ram X18052 .....................$225 200W SWITCH MODE POWER SUPPLY FOR IBM* AT* & COMPATIBLES 3M/Byte Ram X18056 ..................... $275 1 NORTHCOTE: 425 HighSt,Melb. Phone: (03) 489 8866 SYDNEY :74 Parramatta Rd, Stanmore .. NSW. Phone: (02) 519 3134 ~ JOYSTICK FOR IBM* Clock X18024 .................. .....$39 OUTPUT: ___O_D __R_V_I_N_G_...... DEC +5 116A, -5V 0.5A A I . 12v, sA -12v o.5A ELECTRONICS x11097 ... .. .. ... .... s199 MELBOURNE : 48 A·eeckett St, Phone: (03) 663 6151 r~ RITRON CGA COLOUR MONITORS Quality monitor■ without Iha price tag! Dlsplay Tube: 14 Inch 90° deflectlon 0.39mm Dots lrio pitch. Dark l ace sc-,i. Phosphor: P22 Rnolutlon:640 doll (horizontal) 240 line (vertical) exOft>or■ nt X14526 ..................... $395 Serial /Parallel /Games X18151 ..................... $115 Floppy Disk Drive X.18005.......................$52 4 Way Drive Controller 3601</ 7201</ 1.2MI 1.44 X18006 .. ...................$129 XT* Hard DlskController X18060..................... $129 Errors and om1ss1 ons excepted Pnces and spec1hcat1ons sub1ec t 10 ch ange IBM· PC· ,:T· AT· .u e ,eg,ste•l!O 1,a,c1ema ,i.s 01 lnte<n a1,on a 1 e... s,ne ss Mac ri ,nes 'Apple ,s a r<at>9 ,s? e r eCl 1•l'ctemaa Tef lon · ,s a re 9 ,s1e,e<1 H adema , k of Dupon t ·oenonie s •eg ,sler ed ll ademarlls or thetr respec:1,we owners RITRON EGA COLOUR MONITORS Dlsplay Tube: 14 Inch 90° defleetlon dot type black matrix. Standard persistence phosphor. Active Olsplay Area : 240mm x 180mm Rnolutlon: 64 Colour:720dot■(H) • 350 line• 16 Colour:640dot■(H) x 200 llnea X14527 .. .......... ......... $595 BABY AT* COMPATIBLE COMPUTER! 2M/B RAM $1,695 • Anal aa■embllng and teattng In Auatr■ lla! · 4 MIByle Main Boerd, 2 MIByla fitted • Swltchable 8110112 MHz • 1.2 MIByle Floppy Disk Driva • 80286CPU • Colour Gr■ phlcs Dlaplay Cerd • 8Slota • Floppy & Hard Diak Controller • Printer Card and RS232 • Keyboard • 200W Po_, SUpply • Manual • 6 Months Warranty • Size: 360(W) X 175(H) X 405(D)mm With 20 MIByle Hard Dlak.$1,1195 With 40 M/Byle V.C. H.D ....$2,195 With 80 MIBY1• Hard Dlak.$2, 795 ~ j RS232 WIRING ADAPTOR BOX • Male to female • 25 Detachable plug on leads • 2 mm1 Jumpe rs • Ideal tor expenmenl1ng or temporary connect10ns Cat X15665 Only $19.95 0--~ ~ (,£ CAR ANTENNA BOOSTER • In-line instalation • 12V boosts 100% Cat. A12073 ;, CRYSTAL LOCKED WIRELESS MICROPHONE PANEL METERS AND RECIEVER MICROPHONc::;·PECIFICATIONS : GALORE! Transmitting Frequency : 37 1MHz Tran~mlttlng System : crystal oscillation Microphone: Elec!rel cor1denser Power Supply: 9V bancry Range: 300 feel In open held Dimensions : 185 x 27 x 38mm IVeigh't: 160 grams RECIEVER SPECIFICATIONS : Recievlng Freq: 3 7 1 MHz Output Level : 30mV (maximum ) Recievlng System : Super heterodyne crystal osc,llallOn Power Supply : 9V Banery or 9V DC power adapler Volume control Tuning LED Dimensions : 11 5 x 32 x 44mm Weight: 220~rams Cal A10452 We have a g reat range al pa nel meters al great pncesi Cat.No. Description Price 010500 MU450-1mA 12 50 010502 MU45 50·0/50uA 12 50 010504 MU45 0· 100uA 12 50 010510 MU45 0-5A 1250 010518 MU45 0-1A 12 SO 010520 MU45 0- I A 12 SO 010525 MU4 5 0•20V 12 50 010530 MU52E 0- 1A 1-4.50 010533 MU52E O·SA 14 50 010535 MU45 VU PMetre 14 95 010538 MUSS 0·50uA 16 95 010540 MU65 0•1 mA 16.95 010550 MU65 0· 100uA 1695 010560 Ml.;65 0· 20 V 16 95 R.R.P. $113 $7.95 /. , CHROME LED BEZELS 9mm hole . available 3 colour s Descnp11on Pnce $1.20 $1.45 $1 .45 ~ 14030 Ae d S;4032Green S 14034 Yellow ~ HEATSINK COMPOUND Heats1nk compound 1s applied to the base and mo unting studs of transIsIors and diodes 11 ma1nta,ns a pos1hve hea!s1nk seal that improves heat tr ansler fro m the device to the heaIs1nk. thus mcreasmg overall eH1c1ency Cat H 11800 110g) Cat H 11 81 0 !150Q I $2.00 $14.95 TOGGLE SWITCHES Cat No S 1 10 10 $1'020 ULTRASONIC TRANSDUCERS Designed to transmit at 40kHz (L 19990} and receive at 40kHz (L 19991 ) with up to 20V I/ P on the transminer These unit s can·t be heard and so are ideal for T V remote controls. water level detectors . burgalar alarms, moHon detectors and information earners as they can be either pulsed or used ,n the continuous wave mode Full specifications below for design ~ri',:U~ Input vonage : 20V rm s ~~r: ~==r!~:~= o4SRM~: 0 t 10dB min SensHlvtty (dB/v/ubar) min .: - 65 min . Bandwidth (kHz) : Transm it · 4.0 (a t 1OOdB) Receiver 5 O (at 73d8 ) Impedance: Transmit · 500 Receiver 5000 Cat l 19990 (Transmitter ) $4.95 Cat L19991 (Rece,ver) S4.95 6 Oescr1p1 S P OT DPO I ~ • • • • • • • • A13014 . . . R.R.P. S79.95 SPECIAL, ONLY $69.95 Cat. - MINIATURE BUZZER • Female lo Female • Saves moctify1ng o r repl ac ing non-malI ng Centrontes cables • AU 36 pin s w!red s1r a1gh! through C at X 15663 Mate to Male Cat X15661 Male to Female C at X 15664 Female to FPm ■ le N1.J1tnally $33 95 . ~ 5-lSV White or black . Cat. C15062 1-9 $2.50 100 · 10 · $0.12 S0.15 $0.20 $0.15 $0.20 S0.15 $0.10 S0.12 $0.12 S0.12 QUALITY 5mm LEDS RS232 BREAK OUT BOX A srmple wa y o 1 monito r1nq HS2J, 1n,orlace lead actIvIty tnter1 ,IC.P oowe,ed pockel s,ze !or cir cw· testing monitori ng and patch1no 10 sign al powered LED '> ancl ,! spares 24 sw11ches enabtes y,1., IC break o ut circuits 0 1 reeonhgurf' and patch any or all rhe ? ,l ~ c- h,f• posItIons SPECIFICATIONS , Connectors : 0825 plug on 8Qrnrr, ribbon cable and 0825 socke1 Indicators: Tricolou, LEO s !or T D RD RTS C TS DS R C D ·1 C HC OTA (E ITC Jumper Wires : 20 tinned ericl p,~ces Power : Interlace pow er Enclosure : Black hig h Imoac1 plastic Dimensions : 85 • 95 x 30m m X 15700 C::at.T1 2458 ... $6.95 $94.95 Cal. No Col Z IO I 50 Red $2.25 1·9 100 10 · $0.10 $0.09 $0.08 z ,o ,s, G,o $0.15 $0.12 S0. 10 710 152 Ylw $0.15 $0.12 $0.10 SWITCHES II you have two or lour compatible devices !hat need 10 share a th1rd or llflh . then these mexpensIve data transfer sw1lches will save you the tIme•and hassle of constantly changing cables and leads around • No power requ red • Speed and code lransparen! • Two,Four posIh'.)fl rolary switch on tronl panel • Three Five Intenace connectton s on rear panel • Switch comes standard wItt1 female connector 2 WAY RS232 X19 120 ONLY $49 4 WAY RS232 X19125 ONLY $59 2 WAY Centronics X19 130 .. .... . ONLYS49 4 WAY Centronics X19135 ONLY $59 PC BOARD HOLDER Retter than an extra pair ot hands 1 C\ m ust !or all PCB work Cai T12444 $9.95 FLASHING LEADS • Red, 5mm Z101 59 1-10 $1 .10 DE9P OE9S 0 A15P DA 15S Pl0895 P• 0900 P10901 P 10902 P10904 P1 0905 0A1 5S $ 2,50 0 825P $1.00 D825S $1 .00 DB25C $1.00 0825P $2.50 D825S $2.50 ::::! ~;;:~ ~ -=== -=== 10+ $1.00 1·9 $2.50 $2. 75 $1.00 $1.00 P 10884 P10885 P10890 P\ 089 1 $2.50 10+ $1.90 $1 .90 $0.80 $0.80 $1.90 $1.80 $0.80 $0.80 $0.80 $1.90 $1 .90 1·9 1-9 2155 ?40Vb 15V ' A C dt M1 2 1"J~ $9 95 S8 95 21 56 240 V b · · ::, v l A C at Ml;?: 56 $14 95 S1 3 95 1 0 28-4 0 240V 9V C T C.1t M1 28 40 S5 .95 $4 .95 2851 240V 1:-' -6 VC T 1~0 rnA S5 .95 SS .SO 2860 ?40V l'i V C l l 'lOm A M 1?860 $5 .95 $4 95 6672 240V 15 JQV ' A i,1ppe(~ C d ! M 166';' ? $ 14 .95 S13 95 A 117005 Push On ON operation each S1 9.95 $ 3.25 S 4.50 $ 2.75 $ 1.95 $ 2.95 $ 2.95 9 PIN TO 25 PIN CONNECTOR ADAPTORS $8.95 FREE STANDING, FOLD UP MAGNIFIER An ecconomIcally prJCed · hands free· magnifier. lets you take care ol all those !ncky hne detailed Jobs so oflen encountered In electromcs . or any of many other prac!1car uses such as home work. hobbies etc Cat T 10020 Normally $14.95 SPECIAL, ONLY $12.95 . 2SJ49 2SJ56 2SK134 2SK176 1-9 $7.50 $10.00 $6.90 $9.50 10+ $7.00 $9.50 $6.50 $8.90 MIDRANGE HORNS Use thAse quality. all 11'19tal . P1ezo twee!ers tor great top end sound m your band speakers . disco sound system . etc Rated at 30 watts RMS . In a system they will han~ over 100watts AMS Sin : 4··x 10 112·· 8087CHIPS ECONOMY TRANSFORMERS Genuin• Intel c hips with manual and data lllNtf p■ cked in boxes! 8087•3 {4 .TTMHZ) $175 8087·2 {8MHZ) $2$5 8087•1 {10MHZ) $395 80287-6 {6MHZ) $295 80287-ll {8MHZ) $395 80287•10 {10MHZ) $495 80387•16 {16MHZ) $~5 8038720 {20MHZ) $895 80387•25 {25MHZ) $1.095 MEMORY Impedance: 8 ohms Rating : 30 watts RM S RNpon■-: 1 Sk H1 · 14 kHz D t ~ s : 102 x 267 x 177mm Cat C92082 Normally $,19.95 Thi • month only $39.95 Slz•: 3 x UNIVERSAL BATTERY CHARGER AND TESTER Save money on expensive baneries with th,s universal banery charger Features include meter tester. and provisions tor 0 . C. AA. AAA. N . bunon and cell batteries 9V and 6V· (square lypes ) Comes complete with detailed 1nstruct10ns Cat M23533 $29.95 7 ·· lmpeclalee: 8 ohms Rattng: 30 watts AMS RNpORM: 2'kHz - 15 kHz Dtmenak>ns: 76 x 177 x 145mm Cat C92084 Normally $29.95 Thi• month only $24. 95 ~ IUUiffH J NICADS! 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S7 .50 ....... $7.00 41256-12 ..$8 .50 ....... $8.00 41256-10.,$9 .50 .......$9.00 41256-08 ..$9 .90 ••..•.. $9.50 SUPER HORN TWEETER • Requires no crossover and handles up to 100W 1 • Sens1hv1ty 1 OOdB/0 Sm • Frequency Response 3kHz-30kHz • Impedance 8 OHMS • Size 96mm diameter :at c12102 Normally $12.95 SPECIAL, ONLY $9.95 $9.95 $9.50 $8.95 Digital waveform generation using a computer, Pt.3 This month we continue our mini series on digital signal generation with a couple of interesting software listings. By putting in a little work at the keyboard, you can turn your PC into an assortment of audio test gear. By STEVE PAYOR First up, we have an audio tone burst generator capable of generating signals to the IHF standard, or any other you might care to program. Listing 1 and the CRO photographs of Fig.2 provide all the details. The program is written in Borland's TURBO BASIC and achieves a data rate of 20k samples/sec. If you have a copy of TURBO BASIC, the only change you may need to make to the program is the address of the parallel printer port. If you have a different BASIC compiler (eg, Microsoft's QUICK BASIC), try it. Once you have sorted out any minor syntax clifferences, and provided the compiler is not pathetically slow, the only alteration you will have to make is to the SAMPLE.TIME! variable (here set to 50E-6 or 50µs). By the way, the"!" on the end of a variable name makes it a real variable instead of an integer. If you want to save some typing by shortening the variable names, just be careful to keep them of the same type, real or integer, as the original. You can also save a lot of typing by leaving out all the comments, although this may be a false economy in the long run. For the uninitiated, anything to the right of I Data bits D? ~----DURATION----~ BURST .DURATION to 1kHz +OdB -.1dB 0 D-A PC RESISTOR PARALLEL NETWORJ< PRINTER PORT a single quote mark is a comment, or REMark statement. Although these statements are completely ignored by the compiler and contribute nothing to the running of the program, they are worth their weight in gold to the programmer because they describe each step. The tone burst program functions in much the same way as the frequency sweep generator described last month. Once the data array has been filled with bytes, they are output repeatedly until a key is pressed. The time taken for the program to read the keyboard status leaves a tiny "gap" in the waveform. This small gap is not likely to be of any real consequence over the normal tone burst interval of half a second. It becomes an embarrassment, however, if you alter the tone burst parameters in the hope of generating continuous sine waves with this program. Generating a continuous waveform without any gaps is a much more difficult undertaking and this is where our second program excels. IIUIIIIIIIUIUIIIIIIIIUIIIIIIIIIIIIIIIIUIIIIIIII- 3RD ORDER LOW-PASS FILTER DO -STROBE i------------► CRO sync pulse ~ BURST.START Fig.1: how to set up the hardware for the tone burst program of Listing 1. The D-A converter and filter were described in the March 1990 issue. Note that all the parameters of the tone burst (eg, frequency, burst duration, etc) are fully programmable - just change the numbers in the program. 92 SILICON CHIP Listing 1: Tone Burst Generator • SILICON CHIP PROGRAMMABLE AUDIO TONE BURST GENERATOR <TURBO BASIC 1.1> • Copyright CC> Slllcon Chip Publications Pty. Ltd., 1990 • Data rate: 20k saaples/sec <running on a 4.77MHz PC-XT> DEFINT A-Z • All variables are integers unless otherwise indicated DIM TONE.BURST(lOOOO) • At 50vsec/saaple, this array can store up to 500asec • of wavefor• • (Note: The variables listed below are suitable for testing power a•plifiers • to specification IHF-A-202 1978, The Institute of High Fidelity, Inc, USA.> • Variables defining tone burst: FREQUENCYalOOO DURATION=500 BURST.DURATIONa20 BURST.START=20 MIN.AMPLITUDEl=.l • • • • • Frequency <Hz> Total duration (in cycles of sine wave) Burst duration <cycles> Tiae of burst start after CRO sync pulse (cycles> Aaplitude during •quiet• part of burst (0.1 = -20d8) • Prograa constants: PORT.A=&H378 PORT.C=PORT.A+2 Pil=3.141593 SAMPLE.TIMEl=50E-6 • Parallel port • addresses <Note: Other possible base addresses for the printer port are Hex 3BC or Hex 278> • Deterained by experiaent. Change this to suit faster • CPU's, or faster or slower BASIC coapilers • No. of saaples in one cycle SAMPLES=l/FREQUENCY/SAHPLE.TIMEI • Total no. of saaples in entire wavefor• N•SAHPLES*DURATION BURST.END=BURST.START+BURST.DURATION FOR X=O TO SAMPLES-1 • This section of code fills the SINE.WAVEl=127.5*SINCX/SAMPLES*6.2832) • wavefora array with the required FOR CYCLE=O TO DURATION-1 • signal IF CYCLE<BURST.START OR CYCLE>=BURST.END THEN AMPl=HIN.AHPLITUDEI ELSE AMPl=l TONE.BURST(CYCLE*SAMPLES+X>=AHPl*SINE.WAVEl+127.5 NEXT CYCLE • <Be patient - it takes a whole NEXT X • 4 seconds of coaputing tiae> TONE.BURST<N>=128 OUT &H21,INP<&H21) OR 1 • Disable DOS real tiae clock interrupt WHILE NOT INSTAT OUT PORT.C,O • Positive edge of CRO sync pulse FOR X•O TO N:OUT PORT.A,TONE.BURST<X>:NEXT X • Tone burst wavefora OUT PORT.C,1 • Negative edge of CRO sync pulse WEND OUT &H21,INPC&H21) AND &HFE • Restore DOS real tiae clock interrupt END Full range function generator The program of Listing 2 can fit waveform cycles together without any visible seams, thanks to some clever programming. First, it uses a high-speed machine code subroutine to do the actual outputting - we were able to tune this to a speed of exactly 100k samples/sec on an ordinary 4.77MHz XT PC. Second, the code is written in such a way that the time between OUT instructions stays the same, even while the loop counters are being reset. The problem of breaking out of the loop is solved by re-directing the standard keyboard interrupt, which accounts for the complexity of an otherwise short program. Because the interrupt is done by the hardware, no instructions are needed within the loop to check for a keypress . If you are worried about the size of this listing, note that the machine code can be typed in as a simple list of decimal numbers, as shown at the end of the listing. This conMAY 1990 93 Listing 2: Sine, Triangle & Square Wave Generator 10 • SILICON CHIP DIGITAL AUDIO SIGNAL GENERATOR (GWBASIC 3.22) 20 • Copyright CC) Silicon Chip Publications Pty. Ltd., 1990 30 • Data rate: 100k saaples/sec <running on a 4.77MHz PC-XT> 40' 50 DEFINT A-Z • All variables are 16-bit integers unless specified 60 I=O:BYTE•O • otherwise. The variables are being initialised here 70 NO.OF.BYTES=O • for the sole purpose of establishing their locations 80 START.ADDRESS=O • at the start of the GWBASIC data segaent. If an 90 PORT.ADDRESS=&H378 • unused variable happens to appear after the arrays 100 CODE.ADDRESS=O • have been diaensioned, the arrays will be physically 110 FREQ!=O:V=O:Kt=•• • aoved to aake rooa for it, requiring the address 120 • pointer for each array to be re-evaluated 130 • 140 DIM NACHINE.CODE(55) • Sufficient space for 112 bytes of aachlne code 150 DIM BYTE.ARRAY(25000)' Wavefora storage space - 50k bytes - sufficient for 160 • Ii second at a data r ,a te of 100k bytes per second 170 • 180 DEF SEG • Set Data Segaent register to GWBASIC•s data segaent 190 • 200 • MACHINE CODE SUBROUTINE TO OUTPUT A STREAM OF BYTES QUICKLY TO I/O PORT 210 • 220 • Usage: CALL CODE.ADDRESSCPORT.ADDRESS,START.ADDRESS.NO.OF.BYTES) 230 • 240 • The following section sets up the aachine code subroutine in an integer 250 • array MACHINE.CODE, within the GWBASIC data segaent: 260 • 270 START.ADDRESS=VARPTR<MACHINE.CODE<O>> 280 NO.OF.BYTES=t12 290 FOR I=O TO NO.OF.BYTES-1 • This section of code sets up the 300 READ BYTE • aachine code subroutine within 310 POKE START.ADDRESS+I.BYTE • the GWBASIC data segaent 320 NEXT I • 330 • 340 DATA &H8B,&HEC :• MOV BP,SP Load current stack pointer into BP 350 DATA &H8B,&H5E,&H08 :• NOV BX, CBP 1+8 Get address of 1st paraaeter 360 DATA &H8B,&H17 :• NOV DX.CBXJ Load 1/0 port address into DX 370 :• 380 DATA &H8B,&H5E,&H06 :• MOV BX,tBPJ+6 Get address of 2nd paraaeter 390 DATA &H8B,&H37 :• HOV Sl,CBXJ Load SI with starting address of bytes 400 :• 410 DATA &H8B,&H5E,&H04 :• HOV BX,tBP1+4 Get address of 3rd paraaeter 420 DATA &H8B,&HOF :• HOV CX,CBXJ Load no. of bytes into CX 430 :• Clear direction flag 440 DATA &HFC :' CLD 450 :• 460 DATA &HE4,&H21 :• IN AL,21H Get interrupt aask register 470 DATA &HOC,&HOl :' OR AL, 1 Disable tiaer interrupts 480 DATA &HE6,&H21 :• OUT 21H,AL Write interrupt aask register 490 :• 500 : ' The next section of code alters the keyboard 510 : ' interrupt pointers so that a keyboard interrupt will 520 : ' get us out of the continuous signal generation loop 530 :• 540 DATA &HE8,&HOO,&HOO :• CALL 0 Puts IP for next instruction on stack 550 DATA &H5D :' POP BP Gets address of this instruction in BP 560 DATA &H83,&HC5,&H2F :• ADD BP.47 BP now points to the instruction after the •infinite• loop below 570 :' 580 DATA &HB8,&HOO,&HOO :• HOV AX,O Clear AX 590 DATA &H8C.&HDB :• HOV BX,DS Save DS in BX 600 DATA &H8E,&HD8 :• HOV DS,AX Clear OS (to access low aeaory) 610 DATA &HFF,&H36,&H26,&HOO:' PUSH 26H Save CS of interrupt pointer on stack 620 DATA &HFF,&H36,&H24,&HOO:' PUSH 24H Save IP of interrupt pointer on stack 94 SILICON CHIP 630 DATA &HBC,&HOE,&H26,&HOO:' NOV 26H,CS Change CS of interrupt pointer 640 DATA &H89,&H2E,&H24,&HOO:' MOY 24H,BP Change IP of interrupt pointer :• NOV DS,BX Restore OS 650 DATA &HSE,&HDB :, 660 670 DATA &H8B,&HD9 :• MOV BX,CX Make a copy of CX in BX, and SI in DI 680 DATA &HBB,&HFE :' MOV DI,SI so that these registers can be reset : 690 quickly :, 700 710 :' Allowing for aeaory refresh interrupts, the loop 720 :' below executes in alaost exactly 10 psec, on a 730 :• 4.77MHz PC-XT :, 740 750 DATA &H90 :' NOP Adjusts loop tiaing 760 DATA &HAC Load byte into accuaulator : ' LOOS Output byte (40 clocks> 770 DATA &HEE : ' OUT DX,AL 780 DATA &HE2,&HFB Loop CX tiaes : ' LOOP -5 790 DATA &H90 :' NOP :• NOV CX,BX 800 DATA &H8a.&HCB Restore loop counter 810 DATA &H88,&HF7 :• HOV SI,DI Restore string pointer (32 Locks) 820 DATA &HAC Load byte : ' LOOS 830 DATA &HEE : ' OUT DX,AL Output byte 840 DATA &HE2,&HF3 Continue looping ----\40 clocks) :' LOOP -13 :, 850 :• We get here on a keyboard interrupt. Before juaping 860 870 :' to the keyboard interrupt service routine, we need to 880 :' adjust the IRET address on the stack, to force the 890 :' interrupt service routine to return below :, 900 910 DATA &H83,&HC5,&HOC :• ADD BP,12 Adjust BP to point to the interrupt :, 920 address restoration routine below 930 DATA &H83,&HC4,&H02 :' ADD SP,2 Reaove IP for IRET from stack 940 DATA &H55 :• PUSH BP Substitute the desired address : 950 960 DATA &HBB,&HEC :• MOV BP,SP Get stack pointer into BP 970 DATA &HFF,&H6E,&H06 :' JMP CBPl+6 Juap off to service keyboard interrupt :, 980 990 :• Now restore the original keyboard interrupt pointers :, 1000 1010 DATA &HB8,&HOO,&HOO :' HOV AX,O Clear AX :• MOV BX,DS 1020 DATA &HSC,&HDB Save DS in BX 1030 DATA &H8E,&HD8 :' HOV DS,AX Clear OS 1040 DATA &H8F,&H06,&H24,&HOO:' POP 24H Restore IP of keyboard interrupt 1050 DATA &HBF,&H06,&H26,&HOO:' POP 26H Restore CS of keyboard interrupt 1060 DATA &HSE,&HDB :' MOY DS,BX Restore OS :, 1070 1080 DATA &HE4,&H21 :' IN AL,21H Get interrupt aask register 1090 DATA &H24,&HFE Re-enable tiaer interrupts : ' AND AL, FEH 1100 DATA &HE6,&H21 Write interrupt aask register :' OUT 21H,AL :, 1110 1120 DATA &HCA,&H06,&HOO :• RET 6 Return and pop GWBASIC's CALL 1130 :• paraaeters fro• stack . <----,, < <_J . 1140' 1150 • Progra• proper starts here 1160 ' 1170 CLS 1180 INPUT•Frequency <Hz) ••• •,FREQt:IF FREQ1(2 THEN END 1190 NO.OF.BYTES=lOOOOOI/FREQt 'Calculate no. of saaples in one cycle 1200' 1210' The following section of code sets up an array of data bytes for one 1220' cycle of the wavefora. Choose the appropriate calculation for sine, 1230' triangle or square waves by turning the unwanted lines into REM 1240' stateaents with a single quote aark 1250' continued next page MAY 1990 95 Listing 2: continued from previous page 1260 1270 1280 1290 1300 1310 1320 1330 1340 1350 1360 1370 1380 1390 340 350 360 370 380 390 400 410 420 430 440 450 START.ADDRESS=VARPTR<BYTE.ARRAY<O>> FOR I=O TO NO.OF.BYTES-1 • Sine V=l27.5*<l+COS(I/NO.OF.BYTES*6.2832)) • Triangle • V=ABS<IINO.OF.BYTES*2~1)*255 • IF I<NO.OF.BYTES/2 THEN V=O ELSE V=255 • Square • White noise? • V=RND*255 POKE START.ADDRESS+l,V NEXT I • CODE.ADDRESS=VARPTR<MACHINE.CODE(O)) • Get address of subroutine • CALL CODE.ADDRESS(PORT.ADDRESS,START.ADDRESS,NO.OF.BYTES) • K$=INKEY$:GOTO 1180 • Absorb unwanted keypress and request another freq. DATA 139,236,139,94,8,139,23,139,94,6 DATA 139,55,139,94,4,139,15,252,228,33 DATA 12,l,230,33,232,0,0,93,131,197 DATA 47,184,0,0,140,219,142,216,255,54 DATA 38,0,255,54,36,0,140,14,38,0 DATA 137,46, 36,0,142,219,139,217,139,254 DATA 144,172,238,226,251,144,139,203,139,247 DATA 172,238,2 26,243,131,197,12,131,196,2 DATA 85,139,236,255,ll0,6,184,0,0,140 DATA 219,142,216,143,6,36,0,143,6,38 DATA 0,142,219,228,33,36,254,230,33,202 DATA 6,0 (Lines 460 to 1130 omitted) If you don't feel like typing in the detailed machine code in the above listing, substitute these condensed DATA statements instead. denses the whole subroutine into 12 short lines. However, we have included the full listing for those who wish to experiment with the machine code. The main body of the program is written in GW BASIC, since speed is no longer a problem. Some changes to the machine code will be needed to accommodate the differing calling protocol of other languages, such as TURBO BASIC or "C". Included in the listing are lines for generating sine, triangle or square waves. Fig.3 shows each waveform at lkHz. Is Your Product Getting The Exposure It Deserves? Consumers need to see your product if you want them to buy it Contact Paul To Reserve This Space - (02) 982 9553 96 SILICON CHIP There is no reason why other waveforms can't be added; eg, a two-tone audio test signal for SSB transmitters. You will notice that waveform selection is a little primitive - you have to disable the ones that you don't want by inserting a single quote mark - but we have done this to keep the listing short. A proper program would let you choose the waveform at run time. As shown, the program is set for generating sinewaves. To generate triangle waves, all you have to do is insert a single quote mark at the start of line 1280 and delete the quote mark at the start of line 1290. Square waves and white noise can be generated by changing the program in similar fashion. While we're on the subject of limitations, we have removed the need for an anti-aliasing filter by rounding off the number of samples per cycle to the nearest integer. However, this means that the highest frequencies are rounded to the following values: 50kHz, 33.3kHz, 25kHz, 20kHz, 16.7kHz and so on. In order to generate any in-between frequencies, the program needs to step through more than one cycle of the waveform. This will generate a "double sideband" modulated signal, as described last month. The lower frequency limit is determined by how long you are prepare to wait for the array to be filled. A suitable filter will fix this. For a start you can try the simple third order filter described in March, with the L and C values scaled (a) (b) (c) Fig.2: these waveforms were produced by the TURBO BASIC program of Listing 1 . The CRO horizontal axis is not to scale ih these photographs, however the period of each cycle is exactly 1ms. (a) This is what an IHF standard tone burst looks like, or at least a small part of it. The entire tone burst waveform lasts for a whole 500ms and the short + 20dB burst is normally quite hard to capture on a CRO. Our program provides a convenient sync pulse, which can be positioned comfortably ahead of the tone burst. (b) Here we have programmed a much shorter burst so we can check out the waveform quality. As you can see, it is virtually perfect except for a small gap between the end of one burst and the start of the next. This gap occurs when the TURBO BASIC program completes its high-speed output loop and checks the keyboard input. We used this small time interval to put out the CRO sync pulse. (c) This is how the 1kHz waveform looks without a low-pass filter. The relatively low data rate of 20k samples/sec makes a filter essential for good waveform purity (see the March 1 990 issue for complete details of a filter suitable for this data rate). (a) (b) (c) Fig.3: these three photographs show typical waveforms produced by the GW BASIC program of Listing 2, which has been optimised for continuous waveform generation. The horizontal axes are 100µs per division. The output amplitude of the D-A converter has been trimmed to 2.8V peak-to-peak, which gives a nice round figure of 1 V RMS for the sinewave. (a) This is what an unfiltered 1 kHz sinewave looks like at a data rate of 100k samples/sec. For most audio applications, filtering may not be necessary. Note that there are no gaps between the end of one cycle and the start of the next. (b) The triangle wave option, again at 1kHz. (c) The square wave option, also at 1kHz. If you want the square wave to have the same RMS amplitude as the sinewave, use the values 0 and 180 or, better still, 38 and 218 instead of 0 and 255 as in the program . down to increase the - 0. ldB passband from 4kHz to 20-25kHz (ie, divide all the L and C values by 5). This will be fine for sinewaves but square and triangle waves will show a tiny bit of ringing. To do justice to this program, we are currently working on a 5th order filter which has a smoother phase characteristic. This will be built onto a small PC board which will also accommodate the simple A-D converter featured in February. We will also be making available a 360K 5.25-inch floppy disc containing source listings of all the software described so far, along with compiled and executable versions of all the programs (so you won't need to buy a BASIC compiler). These programs will have a number of " user friendly" enhancements which had to be left out of the published listing; because they would have taken up several more pages. ~ MAY 1990 97 Silicon Chip BACK COPIES February 1988: 200 Watt Stereo Power Amplifier; Deluxe Car Burglar Alarm ; End Of File Indicator For Modems; Low Ohms Adaptor For Multimeters; Line Isolation Unit For Phone Patch; Easy Tips On Headphone Repair. March 1988: R~mote Switch For Car Alarms; Telephone Line Grabber; Endless Loop Tape Player; Build Your Own Light Box; New Life For RadioCassette Players; Old-Time Crystal Radio. April 1988: Walkaround Throttle For Model Railroads, Pt.1 ; pH Meter for Swimming Pools; Slave Flash Trigger; Headphone Amplifier For CD Players; What Is Negative Feedback, Pt. 1 ; Mobile Antennas For The VHF & UHF Bands. May 1988: Optical Tachometer For Aeromodellers; High Energy Ignition For Cars; Ultrasonic Car Burglar Alarm ; Walkaround Throttle For Model Railroads , Pt. 2; Designing & Building RF Attenuators; Motorola MC3334P High Energy Ignition IC Data. June 1988: Stereo Control Preamplifier (uses LM833). Pt.1 ; Breakerless Ignition for Cars Using Hall Effect Pickups ; Mega-Fast Nicad Battery Charger; Automatic Light Controller Uses PIR Detector; RF Sniffer Probe & Preamplifier; What is Negative Feedback, Pt.2. July 1988: Stereo Control Preamplifier, Pt.2 ; Fitting a Fuel Cut-Off Solenoid; Booster for TV & FM Signals; The Discolight Light Show, Pt.1; Tone Burst Source for Amplifier Headroom Testing; National Semiconductor LM833 Op Amp Data; What is Negative Feedback, Pt.3 . August 1988: Building a Plasma Display; Universal Power Supply Board ; Remote Chime/Doorbell ; High Performance AC Millivoltmeter, Pt.1 ; Discolight Light Show, Pt.2; Getting the Most Out of Nicad Batteries; Data on Insulated Tab Triacs. September 1988: Hands-Free Speakerphone; Electronic Fish Bite Detector; High Performance AC Millivoltmeter, Pt.2; Vader Voice; Motorola MC34018 Speakerphone IC Data; National Semiconductor LM12 150W Op Amp Data & Applications; What is Negative Feedback, Pt.4. October 1988: Stereo FM Transmitter (uses Rohm BA 1404); High Performance FM Antenna; Matchbox Crystal Set; Electronic House Number; Converting a CB Radio To The 28MHz Band; Electronics & Brock's BMW Blaster; Queensland's Powerful Electric Locomotives . November 1988: 120W PA Amplifier Module (uses Mosfets) ; Poor Man's Plasma Display; Automotive Night Safety Light; Adding a Headset To the Speakerphone; How To Quieten the Fan In Your Computer; Screws & Screwdrivers, What You Need To Know; Diesel Electric Locomotives. December 1988: 120W PA Amplifier (With Balanced Inputs), Pt.1 ; Diesel Sound Generator; Car Antenna/Demister Adaptor; SSB Adaptor for Shortwave Receivers; Electronics & Holden's New V6 Engine; Why Diesel Electrics Killed Off Steam ; Index to Volume 1. January 1989: Line Filter for Computers; ~ ,---------------------------------- • --7 I Please send me a back issue for: □ February 1 988 □ March 1 988 □ April 1 988 I I n May 1 988 rJ June 1988 □ July 1988 □ August 1 988 □ September 1 988 I I □ October 1 988 0 November 1 988 □ December 1988 □ January 1989 □ February 1 989 I I U March 1 989 r-1 April 1989 □ May 1989 □ Ju·ne 1989 □ July 1989 Use this handy form to order your back copies I LJ August 1 989 □ September 1 989 □ October 1989 □ November 1989 I □ January 1 990 0 February 1 990 □ March 1 990 □ April 1990 tI 1 1 I I I I I I I □ December 1989 Enclosed is my cheque/money order for $ _ _ _ _ _ _ or please debit my □ Bankcard □ Visa Card □ MasterCard Card No. J Price: $A5.00 each (includes postage). Overseas orders add Signature _ _ _ _ _ _ _ _ _ _ _ _ Card expiry date_~'--$A 1 .00 per issue for postage . NZ & PNG orders are sent by air mail. Name_ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ (PLEASE PRINT) Detach and mail to: SILICON CHIP PUBLICATIONS Street___ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ PO BOX 139 COLLAROY BEACH NSW 2097 Suburb/town _ _ _ _ _ _ _ _ _ _ _ _ Postcode____ OR FAX: (02) 982 9553 I II I II l I ~--------- -------------------------- ---~98 SILICON CHIP Ultrasonic Proximity Detector for Cars ; Simple Computer Sound Repeater; 120W PA Amplifier (With Balanced Inputs) Pt. 1 ; How to Service Car Cassette Players; Massive Diesel Electrics In the USA. February 1989: Transistor Beta Tester; Minstrel 2-30 Loudspeaker System; LED Flasher for Model Railways (uses LM3909); Build a Simple VHF FM Monitor (uses MC3362). Pt.1 ; Lightning & Electronic Applian ces; Using Comparators to Detect & Measure. March 1989: LED Message Board , Pt.1 ; 32-Band Graphic Equaliser, Pt.1 ; Stereo Compressor for CD Players; Map Reader for Trip Calculations ; Amateur VHF FM Monitor, Pt.2; Signetics NE572 Compandor IC Data; Electronics for Everyone - Resistors. April 1989: Auxiliary Brake Light Flasher; Electronics for Everyone : What You Need to Know About Capacitors ; Telephone Bell Monitor/ Transmitter; 32-Band Graphic Equaliser, Pt.2 ; LED Message Board, Pt.2. May 1989: Electronic Pools/Lotto Selector; Synthesised Tom -Tom ; Biofeedback Monitor For Your PC; Simple Stub Filter For Suppressing TV Interference; LED Message Board , Pt.3 ; Electronics for Everyone - All About Electrolytic Capacitors. June 1989: Touch-Lamp Dimmer (uses Siemens SLB0586); Passive Loop Antenna For AM Radios; Universal Temperature Controller; Understanding CRO Probes; LED Message Board, Pt.3 ; Coherent CW - A New Low Power Transmission Technique. July 1989: Exhaust Gas Monitor (uses TGS812 Gas Sensor) ; Extension For the Touch-Lamp Dimmer; Experimental Mains Hum Sniffers; Compact Ultrasonic Car Alarm ; NSW 86 Class Electrics; Facts On the PhaxSwitch - Sharing Your Phone Line With A Fax Machine. August 1989: Build A Baby Tower AT Computer; Studio Series 20-Band Stereo Equaliser, Pt.1; Garbage Reminder - A 7-day Programmable Timer; Introduction to Stepper Motors; GaAsFet Preamplifier For the 2-Metre Band; Modern 3-Phase Electric Locomotives. September 1989: 2-Chip Portable AM Stereo Radio (uses MC13024 and TX7376P) Pt.1 ; Alarm-Triggered Telephone Dialler; High Or Low Fluid Level Detector (uses LM1830N) ; Simple DTMF Encoder (uses Texas TMC5089); Studio Series 20-Band Stereo Equaliser, Pt.2 ; Auto-Zero Module for Audio Amplifiers (uses LMC669) ; A Guide to Hard Disc Drives . October 1989: Introducing Remote Control ; FM Radio Intercom For Motorbikes (uses BA 1404 and TDA?000) Pt.1 ; GaAsFet Preamplifier for Amateur TV; 1 Mb Printer Buffer; 2-Chip Portable AM Stereo Radio, Pt.2; Installing A Hard Disc in the PC; A Look at Australian Monorails. November 1989: Radfax Decoder For Your PC (Displays Fax, RTTY and Morse); Super Sensitive FM Bug ; Build A Low Cost Analog Multimeter; FM Radio Intercom For Motorbikes, Pt.2 ; 2-Chip Portable AM Stereo Radio , Pt .3; Floppy Disc Drive Formats & Options ; The Pilbara Iron Ore Railways . December 1989: Digital Voice Board (Records Up To Four Separate Messages , Uses Texas TMS3477NL and 256K RAMs); UHF Remote Switch ; Balanced Input & Output Stages ; National Semiconductor LM831 Low Voltage Amplifier IC Data ; Install a Clock Card In Your PC ; Index to Volume 2. January 1990: Service Tips For Your VCR ; Speeding Up Your PC; Phone Patch For Radio Amateurs; High Quality Sine/Square Oscillator; Active Antenna Kit; The Latest On High Definition TV; Speed Controller For Ceiling Fans. February 1990: 16-Channel Mixing Desk; High Quality Audio Oscillator, Pt.2 ; The Incredible Hot Canaries; Random Wire Antenna Tuner For 6 Metres; Phone Patch For Radio Amateurs , Pt.2 ; PC Program Calculates Great Circle Bearings. March 1990: 6/ 1 2V Charger For Sealed Lead-Acid Batteries ; Delay Unit For Automatic Antennas ; Workout Timer For Aerobics Classes ; 1 6-Channel Mixing Desk, Pt.2; Using The UC3906 SLA Battery Charger IC; Digital Waveform GeMration Using a PC; The Controls On A Model Aircraft. April 1990: Dual Tracking ± 50V Power Supply; VOX With Delayed Audio; Relative Field Strength Meter; 16-Channel Mixing Desk, Pt .3 ; Simple Service Tips For Your Microwave Oven ; Model Aircraft Aerodynamics ; Active CW Filter For Weak Signal Reception . Note: November 1 98 7 , December 198 7 & January 1988 are now sold out. Serviceman's Log ctd from page 64 didn't reveal anything, at least he had some background which might assist some of his more experienced colleagues in pinpointing the fault. So, with the bottom cover removed and the PTT button permanently activated - by simply clamping the microphone gently in the bench vice - he went over the boards with an insulated prodder, gently at first, then more vigorously when there was no response. Nothing happened until he touched one corner of the matrix board, ever so gently. The readout flickered and up came the correct frequency. That produced mixed feelings. All the joints on that board were of his own making, so if one was dry it was his fault. But careful scrutiny with a high power glass revealed nothing. What about the 10-pin plug and socket feeding the matrix board? It was a long shot but a spray of contact cleaner wouldn't . do any harm. That done, he was replacing the matrix board when something caught his eye. On the sub-board, beneath the matrix board, there are several components; four ICs, three transistors, and several resistors and capacitors. And it was one of the resistors. These are mounted vertically, with the upper pigtail turned over to return to the board. And each pigtail was protected with a plastic sleeve, in case it made contact with the underside of the matrix board above it. But the sleeve on one resistor had worn through, revealing bare pigtail. And it didn't take a genius to work out that it had been rubbing against the underside of the board, eventually making contact with it. Of course, that was it. The cure was to simply push the resistor over at a slight angle, thus reducing its effective height by a couple of millimetres. That was several weeks ago and there has been no trouble since. But I can't help wondering how many Icom 22S sets may be gathering dust due to a simple fault like this. ~ MAY 1990 99 ASK SIUCON CHIP Got a technical problem? Can't understand a piece of jargon or some electronic principle? Drop us a line and we'll answer your question. Write to: Ask Silicon Chip, PO Box 139, Collaroy Beach, NSW 2097. Electronic advance for high energy ignition I am interested in building a circuit for varying the advance/retard of the high energy ignition system. In particular, I want to use it on a motorcycle. There are three main reasons for using such a circuit: (a) to provide a more a ccurate and adjustable advance curve; (b) to allow the ignition timing to be set simply and easily with a screwdriver; and (c) because the motorcycle in question does not have a mechanical advance/retard unit. The bike is a 1976 860cc Ducati which was originally fitted with a self-energising CDI system. The trigger and energising coils, along with the switching circuitry, were integrated in an epoxy encapsulated crankcase-mounted stator, driven by two magnets on the flywheel. This was unreliable and was tossed. I now have a Joseph Lucas bolt-on goodie which consists of an "ignitron amplifier" (a power transistor circuit for switching the ignition coils) driven by a magnetic reluctor unit on the end of one camshaft. It has a reasonably good reputa- Wants charger for 12V nicad batteries I am very impressed with your 6/12V Charger for SLA Batteries as described in the March 1990 issue of SILICON CHIP. Can I use it to charge 12V nicad batteries? It looks like the ideal solution to a problem I have had for some time. (E.G. Ashfield, NSW). • Absolutely not! You must not use this charger with nicad batteries. It would be very dangerous to do so. The problem with nickel cad100 SILICON CHIP tion although the manufacturers warn you not to fire the ignition when one or other of the plug leads is disconnected. However, as with many electronic units that appear on motorcycles, I don't trust it. My first question is, does the high energy ignition circuit published by SILICON CHIP include protection against failure if a plug lead becomes disconnected? Second, can an electronic advance/retard circuit be incorporated into it? (I.M., Northcote, Vic). • In this issue, we feature a reluctor version of our high energy ignition circuit which could be adapted to motorbike use. As you will see in the article, the circuit does incorporate protection against a plug lead coming adrift in the form of a string of four 75V 5W zener diodes. On the question of advance/retard though, we'll have to pass. The big problem is that ignition advance cannot just be varied as a function of engine revolutions. Throttle setting must also be taken into account these days, to avoid excessive air pollution, as must the air temperature and the engine temperature. It is not a simple matter at all to design a circuit to meet these requirements and even if it was, the mium batteries is that as they come up to full charge, their voltage drops slightly. If they were being charged by the charger described in our March 1990 issue, the circuit would sense this reduction in voltage and then increase the charge rate! That's just exactly what you don't want. We are presently working on a charger circuit for nickel cadmium batteries which, like our SLA circuit, has all the bells and whistles. It will be well worth waiting for. ideal ignition advance characteristics are unique for every vehicle (or motorcycle) type. Do you know the required ignition advance characteristic for your Ducati? We don't. These days, more and more cars have their ignition timing controlled by a microprocessor-based engine management system. The entire advance characteristic for the motor is stored in a ROM (read only memory) which is continually accessed to vary the ignition advance for every firing stroke. Ultimately, we expect that all motor vehicles (trucks, cars and bikes) will have engine management systems to obtain the best performance and economy, and to minimise pollution. In the meantime, building an electronic ignition advance unit is just not a do-ityourself project. We don't think it is, anyway. Components in the Series 200 power amplifier I have a question about capacitors. In your Series 200 power amplifier you specify 100 volt ceramics. I have not been able to locate a source of 0. ltLF/lO0V ceramic capacitors from the catalogs. Geoff Wood Electronics has the smaller ones in 100V and just about all suppliers stock 60V capacitors. Can you suggest an alternative type to suit or a source of 100V types? As far as the output inductors are concerned, how critical is the number of turns? I wound my own on plastic pot core bobbins which seemed to fit your quoted sizes and used the specified length and gauge of wire but was about 3 turns short of the 24.5 turns specified. Is this OK? Finally, I have a query about recording. I was going to get a dual cassette deck but decided I already had an excellent deck. I ultimately purchased a good quality portable stereo player but almost none have Dolby until you get into very expensive units. Now, when dubbing from a Dolby tape, should I record with Dolby on or off and play back with the switch on? I reason that if I record with Dolby from a tape that already has been Dolbied, it is being processed twice. Funnily enough, it sounds terrific. I also assume that if I record without Dolby switched on, from a Dolby tape, then I should play it back with Dolby on and this should even things out. I should trust my ears and do it the way it sounds best but I'd still like to know the correct procedure. (P.G., Orient Point, NSW}. • The 68pF capacitor associated with Q5 need not be ceramic; it could be a polystyrene type rated at 100 volts or more. For the ideal source of polystyrene capacitors, we suggest you contact Allied Capacitors Australia, PO Box 740, Brookvale, NSW 2100. Phone (02} 938 4690. The 0.1µF bypass capacitors are not specified in the parts list as 100V but in any event they are sold as 100V types. As far as the inductor is concerned, by having 3 turns short, the inductance will be about 30% low, since inductance is proportional to the square of the number of turns. It sounds as though your bobbins are not the right size or the wire diameter is not 0.8mm as specified, since the specified number of turns (24.5} fits easily with space to spare. You should really have the correct number of turns otherwise it reduces the effectiveness of the output filter. When dubbing from a Dolby tape, you have a number of options. If your second machine does not have Dolby but you want the dubbed tape to have Dolby on it, you should dub with Dolby off. That way, the new tape will have Dolby on it, the same as recorded on the original tape. On the other hand, if the new tape is intended to be played back on a non-Dolby machine, your Dolby deck should have Dolby switched on Born in the USA; unsuited in Australia Congratulations on your magazine - it provides very interesting reading and learning material. I am studying for a degree in computers and although my knowledge in electronics is limited, I enjoy every page of your magazine. I am writing to you for some guidance on a particular problem in the area of video dubbing. A relative owns a National Panasonic video cassette recorder (model NVL25) which has the facility of NTSC American video playback. The unit works fine with a PAL TV set when playing any American NTSC or PAL video cassette. The problem arises when we try to dub an NTSC tape using the National video machine as the source and a PAL video cassette recorder as the recording unit. We have managed (as a test} to dub a segment of video film with good colour but with frame "hiccup" every so often. We think it is because the NTSC tape is recorded in America using 60Hz. We got in touch with National for playback, for recording via the non-Dolby deck. Make sense? Notes & Errata 2-Chip AM Stereo Radio, October 1989: on page 61, the text regarding the selection of the two .047 µF 2 % capacitors should read ".046µF to .048µF". Also, the artwork on page 66 showing the Sydney radio stations has a small error: the marking for 2FC is lOkHz too high. If you have already made up a Dynamark (Scotchcal) label, the black line can be removed by scrubbing firmly with a cotton bud moistened with methylated spirits. There is no need to remove the 2FC call sign. A new line can be added using Letraset, or microthin black artwork tape. It should line up with 576kHz on the dial instead of 586kHz. Once this is Panasonic in Melbourne and explained our frustrations to one of the technicians. He said that he was aware of the situation but nothing could be done as the unit is designed in Japan. I am hoping that you have an answer or solution to this problem which you may like to suggest to us (L.V., Carrum Downs, Vic}. • There isn't any easy answer to this problem. In fact, we don't see how the machine plays an NTSC tape in colour via a PAL TV set, unless it converts the NTSC signal to a PAL colour signal. The problem is one of incompatible video standards. Not only does NTSC have a 60Hz frame rate versus the 50Hz rate of PAL, but everything else about the signal is different. So as far as dubbing from an NTSC machine to PAL is concerned, there is no way apart from an expensive TV standards converter. Sony and National used to (and may still} make VCRs which could play back PAL, NTSC and SECAM tapes via an RGB colour monitor but they still don't solve the problem of dubbing between differing standards. done, it should be possible to a lign all the dial markings to within less than half a line thickness. Digital Waveform Generation , Computer Bits, March 1990: the CRO photo Fig.6 on page 82 is upside down. Also, in the program listing on page 83 , "50fsec" should read "50µsec ". Although the"µ "' is part of the normal IBM character set, it became an "f" after passing through the magazine's typesetting process. If the sample time for this program really was 50 femtoseconds, it would be something of a breakthrough in computer technology! Active Antenna, January 1990: the overlay diagram on page 20 has the labelling for Q1 and Q2 swapped around. Q2 is near the LED while Q1 is closest to the tuning capacitor, VC1. MAY 1990 101 Cash in your surplus gear. Advertise it here in Silicon Chip. MEMORY CHIPS CLASSIFIED ADVERTISING COUPON 46 Advertising rates for this page: Classified ads - $7 .00 for up to 15 words plus cents for each additional word; Display ads (casual rate) - $20 per column centimetre (max. 10cm). Closing date: five weeks prior to month of sale. If you use a PO Box number, you must include your permanent address and phone number for our files. We cannot accept ads submitted without this information. To run your own classified ad, put one word on each of the lines below and send this form with your payment to: Silicon Chip Classifieds, PO Box 139, Collaroy Beach, NSW 2097. Prices at February ht, 1990 Speed Chip type SIMMS 9 9 (MACS) 8 (IBM) 9 SIPPS 9 x 256 9 x 1Mb DIP 411000 (1Mb) 414256 (1 Mb) 41256 41464 (256) 4164 ZIP 414256 (1 Mb) 41256 411000 (1Mb) 4400 (4Mb) PLEASE PRINT EACH WORD SEPARATELY, IN BLOCK LETTERS 2 6 4 3 5 x 256 x 1Mb x 1 Mb x 1 Mb HP PS2 Sales Tax 20% 7 8 10 9 120ns 100ns B0ns Prices (excluding tax) 40.00 48.00 128.00 132.00 122.00 130.00 165.00 44.00 52.00 132.00 136.00 12.70 13.40 13.80 14.60 3.50 4.10 4.40 4.25 4.60 2.30 2.50 2.70 4.00 16.00 Overnight delivery 18.00 5.00 18.00 - 20.00 150.00 Credit cards welcome DISCOUNTS FOR DEALERS Phone for pricing on 70ns, 80ns, PS2, Compaq, and NTX 12 11 13 14 15 ($7 00) PELHAM Tel (02) 427 0011 - Fax (02) 428 5460 16 ($7.40) 17 ($7.80) 18 ($8.20) 19 ($860) 20 ($9 00) 21 ($9.40) 22 ($9.80) 23 ($10 20) 24 ($10.60) 25 ($11.00) FIX-A-KIT NO CHARGE FOR KITS THAT CAN'T BE REPAIRED 3 MONTHS WARRANTY ON REPAIRS CONSTRUCTION AVAILABLE Name Street Postcode Suburb/Town Enclosed is my cheque or money order for $ Bankcard D Visa Card D MasterCard or please debit my D Card No I I Signature ... ANTIQUE RADIO ANTIQUE RADIO RESTORATIONS. Your one-stop electronic repair shop. Specialising in restoring vintage radios including chassis rewiring , quality new parts, valves, valve sockets, speakers, transformers, cabinet restoration. Quality secondhand radio dials & parts for most brands & models. About 400 radios in stock for restoration & parts. Every restored wireless is covered by a 2-year warranty on parts & service . French polishing of timber cabinets available. Vintage car radios in valve & transistor types available for restoration. Repairs done on tape decks, amplifiers, TVs & videos. Open Sat. 1Oam-5pm; Sun. 12.30-5pm. 109 102 $20 PER HOUR LABOUR SILICON CHIP Card expiry date ...... ./ ..... .. . Cann St, Bass Hill, NSW 2197. Phone (02) 645 3173 BH or (02) 726 1613 AH. HYCAL INSTRUMENTS DESIGN, MANUFACTURE, REPAIR OF ELECTRONIC EQUIPMENT (02) 633 5897 PUBLIC DOMAIN & shareware software for IBM & compatibles . Catalog disc $4 .00 on 5.25-inch 360K or 3.5-inch 720K disc. Also TVREPAIR.TXT which covers faults in most popular brands. It can save hours of work. Just $29 inc. p/post. Martins Television Service, PO Box 1013, Taree , NSW 2430. FOR SALE COMPONENTS: 100,000 3300pF 50V miniature ceramic capacitors $300; boxes of 500 4 70pF, 680pF 3kV and 330pF, 220pF 1kV - $25 each; grain oriented steel sheet, 1 ,OOOkg, each 290 x 1 20mm & 250 x 95mm - $1 000 the lot; boxes of 800 .01µF monolithic capacitors, 1OOV, 0.2mm spacing - $25 per box; brand new Murata disc capacitors, 1OkV working, 30kVA, size 110mm x 15mm - $25 each. AvComm Pty Ltd, PO Box 386, Northbridge, 2063 . Phone (02) 9497417. TOSHIBA T3100 co-proGessor kit. This piggy-back board enables the fitting of an 80287-8 to the early T3100. Two types available, solder in & plug in. Solder version $250.00. Plug-in version $375.00. Import Technologies (07) 372 5138. WOW! DRAM PRICES have dropped. Now is the right time to build your own parallel printer buffer. Advertised since January 1985. Featured in AEM in March 1987 and SILICON CHIP in October 1989. Over 2500 units sold. r~-------------·- -------, BINDERS & SUBSCRIPTION COUPON To: Freepost 25, Silicon Chip Publications, PO Box 139 Collaroy Beach, NSW 2097, Australia. NO POSTAGE STAMP REQUIRED IN AUSTRALIA. D New subscription Start in _ _ _ _ _ _ __ D Renewal 0 Please send me_ ___ SILICON CHIP binder(s) at $A 11 .95 plus $A3 p&p each (NZ p&p $A6). Name _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ (PLEASE PRINT) Street._ __ _ __ __ _ _ _ _ _ _ _ _ _ __ _ _ __ Suburb/town _ _ _ _ _ _ _ _ _ _ _ _ Postcode_ _ _ _ __ Australia 1 year (12 issues) D $A42 NZ & PNG (airmail) Overseas surface mail Overseas airmail D $A65 D $A62 D $A 120 2 years (24 issues) D $A84 D $A130 D $A130 D $A240 Enclosed is my cheque/money order for $ _ _ _ _ or please debit my D Bankcard D Visa Card D MasterCard Signature_ _ _ _ __ __ _ _ _ _ Card expiry date_~-- Same kit, just updated. Now SK-1 M. No obligation. For a free catalog send a 41 c stamp to Don McKenzie, 29 Ellesmere Crescent, Tullamarine 3043. BELT KITS FOR VCRs. Please supply brand & model number & $12.00 for each kit required. Prompt dispatch assured. James Cotterill, PO Box 44 , Farrer, ACT 2607. SOLAREX SOLAR PANELS & accessories at trade prices. Send SAE to Solar Technology, PO Box 1129, Esperance, WA 6450. SATFAX: NOAA, METEOR & GMS weather satellite picture receiving program for IBM XT/AT. Displays in 64 colours. Needs EGA colour monitor & card and "Weather Fax" PC card. $45 plus $3 postage. RADFAX2: HF WEATHER FAX, Morse & RTTY receiving program for IBM XT/AT. Needs CGA, SSB HF, FSK/tone decoder. Also "RF2HERC" & "RF2EGA", same as RADFAX2 but suitable for Hercules & EGA cards respectively. $35 plus $3 postage. All programs are on 5.25-inch 360K or 3.5-inch disc & include full documentation. Only from M. Delahunty, 42 Villiers St, New Farm, Qld 4005. Phone (07) 358 2785. LOGIC ANALYSER. Gould Instruments K40 stand alone analyser. Eight nonvolatile memories, 7-inch CRT, 4 x 2K sample memories, 2 x 16-channel, probes up to 1 00MHz, asynchronous capture. Weighs 7.7kg. $1345.00. Import Technologies (07) 372 5138. EPSON P80 PORT ABLE battery rechargeable SO-column printer. Serial interface. Very compact & light. 1 .1 kg . Uses normal or thermal paper. $1 7 5 . Import Technologies (07) 372 5138. NEW SERVICE - PARTS location and supply. Want just that part of a kit or just a hard to find part? We will find and supply them for you . No search fees. Send SSAE with requirements to Part Search, PO Box 491, Noarlunga Centre, SA 5168. Phone (08) 382 8919. TOSHIBA LCD SCREEN. Originally to suit T1500 desktop. 240 x 180mm, Advertising Index Access Communications ... ...... 3 Allied Capacitors .. ....... ..... .. .. 45 Altronics .......... ......... ..... 56-59 Arista ... .. ....... .. ... ......... ... .... 23 Aust. Test & Measurement .... 73 AvComm Pty Ltd ...... ...... ...... 63 Board Solutions ..... .. ....... 12, 13 Dauner Electronics ..... .... ... .... 89 David Reid Electronics ... ... ... IFC Dick Smith Electronics ... .. .. .. 6, 7 Electronic Solutions ........ 46,4 7 Elmeasco ... ... ....... ... .... .. 17,87 Force Electronics ......... .... ... 41 Geoff Wood Electronics .. ...... 51 Harbuch Electronics ... .. ... 8 7, 89 Hycal Instruments .. ............ 1 02 Jaycar Electronics 26-29, 78-81 Jiloa ........ ... ........................ 11 Novacastrian Electronics . . OBC PC Marketplace ... ... .... .. ... ... IBC Pelham ....... .. ...... .. .... .. .. .. .. 102 RCS Radio ......... ........ ... .... .. 64 Resurrection Radio ....... ... ...... 11 Rod Irving Electronics ..... 90,91 Sheridan Electronics ........ .... 85 PC Boards Printed circuit boards for SILICON CHIP projects are made by: • RCS Radio Pty Ltd, 651 Forest Rd, Bexley, NSW 2207. Phone (02) 587 3491. • Jemal Products, 5 Forge St, Welshpool , WA 6106. Phone (09) 350 5555 . • Marday Services, PO Box 19-189, Avondale, Auckland, NZ. Phone 88 5730. • Electronic Toy Services, 2/ 111 Glynville Drive, Hackham West, SA 5163. Phone (08) 382 8919. 640 x 200 pixels. Uses 5V supply & TTL drive signals. Suit experimenter. $150. Import Technologies (07) 372 5138. BWD OSCILLOSCOPE, 35MHz Dual Trace Model 830. Brand new - never used. Super bargain at $800. Contact Claude on (086) 28 2435 anytime. ALL TYPES OF ASTRONOMICAL telescopes & related accessories, new & secondhand. Best prices in Australia. Contact Astronomy & Electronics Centre, PO Box 45, Cleve, SA 5640. Phone 086 28 2435. MAY 1990 103 Don't miss a single issue IF YOU'RE THE KIND OF READER that can't wait to get the next copy of SILICON CHIP, then why not have the magazine delivered direct to your door? Each month, we'll bring you the best and brightest electronics magazine in the business, put together by Australia's most experienced team. Here's what to look for in each issue: * Constructional Projects For The Enthusiast * Amateur Radio: Theory & Projects * The Serviceman's Log * Computer Bits: Getting The Most From Your PC * Vintage Radio: A Fascinating Hobby 24 Hour Fax Service (02) 982 9553 Send the coupon with your Credit Card details. 24 Hours, 7 Days a week. Sabscr·L Toda byfillin lllaiJ· s - 9 lue y out and •ng tllis Ubscript· -------.:.::•o:n~~ coupon 1 r----------------- -----Freepost * Subscription Coupon D Renewal D New subscription Start in _ _ _ _ _ __ Name _ _ _ __ _ _ _ _ _ __ __ _ _ _ _ _ __ (PLEASE PRINT) Subscription Hotline Telephone (02) 982 3935 9am-5pm Mon-Fri and quote your Bankcard, Visa Card or MasterCard No. and expiry date. Detach Coupon and Mail to: FREEPOST 25 SILICON CHIP PUBLICATIONS PO BOX 139 COLLAROY BEACH NSW 2097 *No postage stamp required in Australia. 104 SILICON CHIP Street_ _ _ _ __ __ _ _ __ _ __ _ _ _ _ __ Suburb/town _ _ __ _ _ _ _ __ _ _ Postcode _ _ __ year ( 1 2 issues) D $A42 Australia NZ & PNG (airmail) D $A65 Overseas surface mail D $A62 D $A 1 20 Overseas airmail Enclosed is my cheque/money order for $ _ D Bankcard Card No . I D Visa Card 1 11 i 2 years (24 issues) D $A84 D $A130 D $A130 □ $A240 _ _ or please debit my D MasterCard 11111 1 I 1 1 W 1 Signature _ _ __ _ _ _ __ Card expiry date_ _ / __ / _ _ ~ L ________________ _______ J CAPACITY COMPUTER PART# SIZE AMIGA AMIGA AMIGA D2930 D2932 D2938 3.5" 5.25" 3.5" 880K 360/880K 880K AMSTRAD D2904 3.5" 720K ATARI ATARI D2916 D2918 3.5" 5.25" 720K 3601720K IBM IBM IBM IBM D2946 D2948 D2950 D2952 3.5" 3.5" 5.25" 5.25" TOSHIBA TOSHIBA D2970 D2972 ZENITH ZENITH COMPAQ COMPAQ COMMENTS PRICE WITH ON/OFF SWITCH WITH ON/OFF SWITCH INTERNAL KIT FOR A2000 249.00 299.00 229.00 FOR PC1512/1640 269.00 WITH POWER SUPPLY SWITCHABLE , WITH POWER SUPPLY 269 .00 299.00 720K 1.4MB 360K 1.2MB WITH WITH WITH WITH 299.00 329 .00 299.00 329.00 5.25" 5.25" 360K 1.2MB SUIT TOSHIBA LAPTOP SUIT TOSHIBA LAPTOP 349.00 399.00 D2976 D2978 5.25" 5.25" 360K 1.2MB SUIT ZENITH SUPER SPORT SUIT ZENITH SUPER SPORT 349.00 399.00. D2980 D2982 5.25" 5.25" 360K 1.2MB SUIT COMPAQ SLT 286 SUIT COMPAQ SLT 286 349.00 349.00 ADAPTER ADAPTER ADAPTER ADAPTER INTERFACE INTERFACE INTERFACE INTERFACE & & & & CABLE CABLE CABLE CABLE ALL TOSHIBA/ZENITH/COMPAQ DRIVES INCLUDE EXTERNAL POWER SUPPLIES, INTERFACE AND CABLES WE ALSO HAVE A RANGE OF DRIVES FOR OTHER BRANDS SUCH AS APPLE AND MACINTOSH AS WELL AS A RANGE OF BARE DRIVES IN 360K/720K/1.2MB/1.44MB/2.88MB FORMATS Have you seen our catalog? Write or phone today for your FREE copy. Over 100 products shown with full details and specifications! BEWARE! We are aware of some cheap drives coming from Taiwan, using inferior drive mechanisms. REMEMBER : ALL ROCTEC drives use QUALITY Japanese mechanisms and are covered by a 12 month warranty. The drives are supported by us under an exclusive agreement with the manufacturer. DEALER ENQUIRIES WELCOME PERSONAL COMPUTER MARKETPLACE P1vud PHONE (02) 418 6711 FAX (02)4186713 Mail Order Address: P.O. Box 1100 Lane Cove NSW2066 FREIGHT CHARGES Include $10 with order for all normal items - heavy items, e.g. monitors add $15. 14 day money back guarantee Order by phone (use credit card), by fax or by mail. Unless insurance is declined it will be charged at 1% of total purchase. This is for your protection. PRICES VALID AT 1 MAY 1990 VISA /x---;,, ,IMasterea~ \ __Y... J',