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GETTING INTO CAR MODS? GET INTO THIS BOOK! From the pages of Australia’s most dynamic electronics magazine, Silicon Chip, come 20 electronic projects you can build for your car. Not just circuits, but complete articles with complete instructions, including fitting. Even the novice constructor can do it! YES! Twenty great projects for cars, including: ✦ High Energy & Breakerless Ignition Systems ✦ Ultrasonic Alarm ✦ Digital Tachometer ✦ Coolant Level Alarm ✦ Flashing Alarm Light ✦ Talking Headlight Reminder ✦ UHF Remote Switch ✦ Thermostatic Switch For Electrically Operated Radiator Fans ✦ And much more! ✦ Bonus: there are eight quick circuit ideas too. All this for only $895 ORDER FROM: (+$3 p&p) Yes! Please send me ____ copies of 20 Electronic Projects For Cars Enclosed is my cheque/money order for $­________ or please debit my ❏ Bankcard   ❏ Visa Card   ❏ Master Card Card No. Signature­­­­­­­­­­­­_____________________________ Card expiry date_____/_____ Name ___________________________Phone No (____)_____________ PLEASE PRINT Street _____________________________________________________ Suburb/town _______________________________ Postcode___________ Order today: phone, fax or mail . . . Simply phone (02) 9979 5644 & quote your credit card number; or fill in the coupon & fax it to (02) 9979 6503 (any time); or mail the coupon to Silicon Chip Publications, PO Box 139, Collaroy, NSW 2097. Vol.8, No.10; October 1995 Contents FEATURES 4 Automotive Ignition Timing; Pt.2 A look at how programmable engine management ECUs are allowing specialist engine tuners to devise their own ignition maps – by Julian Edgar 66 Computer Bits: Connecting To The Internet With Windows 95 FAST CHARGER FOR NICADS – PAGE 54 Microsoft’s new Windows 95 makes it easy to connect to the Internet. Here’s a quick look at what’s involved – by Geoff Cohen PROJECTS TO BUILD 16 Build A Compact Geiger Counter This easy-to-build device will detect alpha, beta and gamma radiation and generates an audible output. It’s based on a Geiger Muller tube and is powered by a 9V battery – by John Clarke COMPACT GEIGER COUNTER FOR RADIATION CHECKS – PAGE 16 22 A 3-Way Bass Reflex Loudspeaker System New design uses high-quality Vifa drivers for high power handling and great sound – by Leo Simpson 32 Railpower MkII: A Walk-Around Throttle For Model Railways; Pt.2 The full construction details and the testing procedure, plus brief troubleshooting details – by Rick Walters 54 A Fast Charger For Nicad Batteries Fast charges 5-10 cells at once from a 12V car battery and automatically reverts to trickle mode at the end of the charging cycle – by John Clarke 74 Digital Speedometer & Fuel Gauge For Cars Update your car’s dashboard to a fancy electronic display. Includes a 6-position overspeed alarm as well – by Jeff Monegal SPECIAL COLUMNS 40 Serviceman’s Log BUILD A HIGH-POWER 3-WAY LOUDSPEAKER SYSTEM – PAGE 22 The view was fabulous, but ... – by the TV Serviceman 86 Vintage Radio Vibrators: a slice of history – by John Hill DEPARTMENTS 2 Publisher’s Letter 10 Circuit Notebook 31 Order Form 82 Product Showcase 92 Ask Silicon Chip 94 Market Centre 96 Advertising Index DIGITAL SPEEDOMETER AND FUEL GAUGE FOR CARS – PAGE 74 October 1995  1 Publisher & Editor-in-Chief Leo Simpson, B.Bus. Editor Greg Swain, B.Sc.(Hons.) Technical Staff John Clarke, B.E.(Elec.) Robert Flynn Rick Walters Reader Services Ann Jenkinson Advertising Enquiries Leo Simpson Phone (02) 9979 5644 Regular Contributors Brendan Akhurst Garry Cratt, VK2YBX Marque Crozman, VK2ZLZ Julian Edgar, Dip.T.(Sec.), B.Ed John Hill Jim Lawler, MTETIA Philip Watson, MIREE, VK2ZPW Jim Yalden, VK2YGY Bob Young Photography Stuart Bryce SILICON CHIP is published 12 times a year by Silicon Chip Publications Pty Ltd. A.C.N. 003 205 490. All material copyright ©. No part of this publication may be reproduced without the written consent of the publisher. Printing: Macquarie Print, Dubbo, NSW. Distribution: Network Distribution Company. Subscription rates: $49 per year in Australia. For overseas rates, see the subscription page in this issue. Editorial & advertising offices: Unit 34, 1-3 Jubilee Avenue, Warrie­ wood, NSW 2102. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 9979 5644. Fax (02) 9979 6503. PUBLISHER'S LETTER Smoke detectors are not a health hazard This month’s topic is prompted by our publication in this issue of a Geiger counter. This itself was prompted by the French, scheduling nuclear tests in the Pacific. Now let me say, at the outset, that I don’t believe that Australia will experi­ence any increase in radiation because of these tests, either now or in the future. We are too far away for that to happen. That does not justify the tests though – nothing can. Australia is right to protest loud and long about the tests, if only to pro­tect the rights of the small nations in the Pacific. But to get to the topic which was prompted by the Geiger counter – smoke detectors. As part of the article on the Geiger counter we have suggested that readers can partly dismantle a smoke detector to expose the radioactive source within. No doubt there will be some readers who will be upset at this but what we are proposing is perfectly safe. Sure, if someone decides to be stupid and eats the minute amount of Americium 241, they will probably die in the fullness of time. I am sure that the vast majority of readers would agree that smoke detectors present no hazard at all but would you believe that the NSW Environmental Protection Authority is really worried about them. Their scenario goes like this: now that governments have made it mandatory for all new houses to have smoke detectors installed, millions of these devices will eventu­ally be thrown out and will end up in landfill and thereby con­stitute a future hazard. The EPA therefore wants all smoke detec­tors to be returned to the manufacturers when they are ultimately disposed of. Now a few moment’s thought will show that this is yet another example of rampant bureaucracy. Let’s say that a million smoke detectors all ended up dumped in the same landfill in 20 years time. Americium 241 has a half-life of 400 years, so the alpha source will have barely deteriorated at all. So each smoke detector contains 0.9 microcu­ries and they constitute a total radioactive deposit of 0.9 curies and therefore could constitute a danger to the environ­ment! Clearly, this is utter nonsense. The same landfill would also contain several million tonnes of other garbage and there­fore the radioactivity of the whole dump would be no more than the rest of the landscape. The garbage would “dilute” the radio­activity. And any runoff from the landfill would no doubt contain far more lethal chemicals than Americium 241. The very concept of returning smoke detectors to the manu­facturers is crazy. These devices can presently be purchased at around $8.00 from large retailers like Woolworths. At that price, today’s manufacturers (in Asia, of course) are not likely to be able to afford to recycle millions of dud smoke detectors. The big advantage of smoke detectors is that they can save lives. Let’s not complicate their use by requiring that they must be returned for recycling at some time in the future. Leo Simpson ISSN 1030-2662 WARNING! SILICON CHIP magazine regularly describes projects which employ a mains power supply or produce high voltage. All such projects should be considered dangerous or even lethal if not used safely. Readers are warned that high voltage wiring should be carried out according to the instructions in the articles. When working on these projects use extreme care to ensure that you do not accidentally come into contact with mains AC voltages or high voltage DC. If you are not confident about working with projects employing mains voltages or other high voltages, you are advised not to attempt work on them. Silicon Chip Publications Pty Ltd disclaims any liability for damages should anyone be killed or injured while working on a project or circuit described in any issue of SILICON CHIP magazine. 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. SILICON CHIP also disclaims any liability for projects which are used in such a way as to infringe relevant government regulations and by-laws. Advertisers are warned that they are responsible for the content of all advertisements and that they must conform to the Trade Practices Act 1974 or as subsequently amended and to any governmental regulations which are applicable. 2  Silicon Chip HEWLETT PACKARD 334A Distortion Analyser HEWLETT PACKARD 200CD Audio Oscillator • measures distortion 5Hz600kHz • harmonics up to 3MHz • auto nulling mode • high pass filter • high impedance AM detector HEWLETT PACKARD HEWLETT PACKARD 3400A RMS Voltmeter 5328A Universal Counter • voltage range 1mV to 300V full scale 12 ranges • dB range -72dBm to +52dBm • frequency range 10Hz to 10MHz • responds to rms value of input signal • 5Hz to 600kHz • 5 ranges • 10V out • balanced output HEWLETT PACKARD 5340A Microwave Counter • allows frequency measurements to 500MHz • HPIB interface • 100ns time interval • T.I. averaging to 10 ps resolution • channel C <at> 50ohms • single input 10Hz - 18GHz • automatic amplitude discrimination • high sensitivity -35dBm • high AM & FM tolerance • exceptional reliability $1050 $79 $475 $695 $1950 BALLANTINE 6310A Test Oscillator BALLANTINE 3440A Millivoltmeter AWA F240 Distortion & Noise Meter ...................... $425 AWA G231 Low Distortion Oscillator ...................... $595 EATON 2075 Noise Gain Analyser ...................$6500(ex) EUROCARD 6 Slot Frames ........................................ $40 GR 1381 Random Noise Generator ........................ $295 HP 180/HP1810 Sampl CRO to 1GHz ................... $1350 HP 400EL AC Voltmeter .......................................... $195 HP 432A Power Meter C/W Head & Cable .............. $825 HP 652A Test Oscillator .......................................... $375 HP 1222A Oscilloscope DC-15MHz ........................ $410 HP 3406A Broadband Sampling Voltmeter ................................................................ $575 HP 5245L/5253/5255 Elect Counter ....................... $550 HP 5300/5302A Univ Counter to 50MHz ................ $195 HP 5326B Universal Timer/Counter/DVM ............... $295 HP 8005A Pulse Generator 20MHz 3 Channel ........ $350 HP 8405A Vector Voltmeter (with cal. cert.) ......... $1100 HP 8690B/8698/8699 400KHz-4GHz Sweep Osc ............................................................ $2450 MARCONI TF2300A FM/AM Mod Meter 500kHz-1000MHz ................................................... $450 MARCONI TF2500 AF Power/Volt Meter ................. $180 SD 6054B Microwave Freq Counter 20Hz-18GHz ......................................................... $2500 SD 6054C Microwave Freq Counter 1-18GHz ............................................................... $2000 TEKTRONIX 465 Scope DC-100MHz .................... $1190 TEKTRONIX 475 Scope DC-200MHz .................... $1550 TEKTRONIX 7904 Scope DC-500MHz .................. $2800 WAVETEK 143 Function Gen 20MHz ...................... $475 FLUKE 8840A Multimeter RACAL DANA 9500 Universal Timer/Counter • true RMS response to 30mV • frequency coverage 10kHz1.2GHz • measurement from 100µV to 300V • stable measurement • accuracy ±1% full scale to 150MHz • list price elsewhere over $5500 • 2Hz-1MHz frequency range • digital counter with 5 digit LED display • output impedance switch selectable • output terminals fuse protected $350 $795 HEWLETT PACKARD 1740A Oscilloscope RADIO COMMUNICATIONS TEST SETS: IFR500A ............................................................... $8250 IFR1500 .............................................................. $12000 MARCONI 2955A .................................................. $8500 SCHLUMBERGER 4040 ........................................ $7500 TEKTRONIX 475A Oscilloscope TEKTRONIX 7603 Oscilloscope (military) • frequency range to 100MHz • auto trigger • A & B input controls • resolution 0.1Hz to 1MHz • 9-digit LED display • IEEE • high stability timebase • C channel at 50 ohms • fully programmable 5½ digit multimeter • 0 to 1000V DC voltage • 0.005% basic accuracy • high reliability/self test • vacuum fluoro display • current list $1780 $695 $350 TEKTRONIX FG504/TM503 40MHz Function Generator TEKTRONIX CF/CD SERIES CFC250 Frequency Counter: $270 • DC-100MHz bandwidth • 2-channel display mode • trigger - main/delay sweep • coupling AC, DC, LF rej, HF rej $990 • 250MHz bandwidth • 2-channel display mode • trigger - main/delay sweep • coupling AC, DC, LF rej, HF rej • mil spec AN/USM 281-C • triggers to 100MHz • dual trace • dual timebase • large screen $1690 $650 The name that means quality CFG250 2MHz Function Generator $375 • 0.001Hz-40MHz • 3 basic waveforms • built-in attenuator • phase lock mode $1290 CDC250 Universal Counter: $405 NEW EQUIPMENT Affordable Laboratory Instruments PS305 Single Output Supply SSI-2360 60MHz Dual Trace Dual Timebase CRO • 60MHz dual trace, dual trigger • Vertical sens. 1mV/div. • Maximum sweep rate 5ns/div. • Built-in component tester • With delay sweep, single sweep • Two high quality probes $1110 + Tax Frequency Counter 1000MHz High Resolution Microprocessor Design CN3165 • 8 digit LED display • Gate time cont. variable • At least 7 digits/ second readout • Uses reciprocal techniques for low frequency resolution $330 + Tax Function Generator 2/5MHz High Stability FG1617 & FG 1627 • • • • • • Multiple waveforms 1Hz to 10MHz Counter Output 20V open VCF input Var sweep lin/log Pulse output TTL/CMOS FG1617 $340 + Tax FG1627 $390 + Tax PS303D Dual Output Supply • 0-30V & 0-3A • Four output meters • Independent or Tracking modes • Low ripple output $420 + Tax • PS305D Dual Output Supply 0-30V and 0-5A $470 + Tax PS303 Single Output Supply • 0-30V & 0-3A • Two output meters • Constant I/V $265 + Tax Audio Generator AG2601A • 10Hz-1MHz 5 bands • High frequency stability • Sine/Square output $245 + Tax • 0-30V & 0-5A $300 + Tax PS8112 Single Output Supply • 0-60V & 0-5A $490 + Tax Pattern Generator CPG1367A • Colour pattern to test PAL system TV circuit • Dot, cross hatch, vertical, horizontal, raster, colour $275 + Tax MACSERVICE PTY LTD Australia’s Largest Remarketer of Test & Measurement Equipment 20 Fulton Street, Oakleigh Sth, Vic., 3167   Tel: (03) 9562 9500 Fax: (03) 9562 9590 **Illustrations are representative only Pt.2: user programmable systems vary the maps Automotive Ignition Timing Programmable engine management ECUs are now allowing specialist manufacturers to devise their own ignition maps. Here’s a quick look at what’s involved. By JULIAN EDGAR The use of programmable engine management ECUs has meant that ignition timing maps can be developed which take into ac­count more than just load and engine speed. Correction for vary­ing intake air and engine coolant temperatures can be provided and much greater advance can be specified than was possible with conventional distributors. While initially affecting only those developing highly-modified road cars or race machines, the freedom of having total ignition timing control meant that new fields had to be explored. Craig Allan is one of the few people formally qualified (he has a Diploma in Engineering) and also active in the modified automo­tives field. Working with son Adam, the Adelaide-based principal of Allan Engineering says: “What computer engine management The advent of programmable engine management ECUs has meant that there is total freedom in devising ignition maps. Any advance can be specified at any load and RPM, with corrections able to be made on the basis of input from the coolant and inlet air temperature sensors, knock sensor and so on. 4  Silicon Chip did was teach us that we still had a lot of learning to do”. With manufacturers selling programmable engine management systems in the field, there was also a need for a major educational campaign. Australian manufacturer Invent Engineering (maker of Haltech programmable engine management ECUs) decided that a formal warning about the dangers of improper ignition timing should preface the running of their software. “WARNING: Poorly adjusted ignition timing can damage your engine... Engine failure can cause an engine to explode and cause a potential vehicle accident ...” reads their statement in part. It goes on to suggest that you return their product if you are unhappy with this idea! However, for the programmable engine management manufactur­ ers to be able to sell their products, some ignition timing guidelines are needed. Ironically – considering the gravity of their warning – Haltech are amongst the best in facilitating the development of ignition maps. The QuickMAP system used by their proprietary software requires only the input of an 8-digit alphanumeric code to configure an ignition timing map for all engine loads. An example of the code used is ‘15A38D10’. This is trans­ lated as follows: • 15 – ignition timing advance angle at idle; • A – 1500 RPM for full ignition advance (‘A’ indicates 1500 RPM, ‘B’ 2000 RPM, etc); • 38 – full load ignition advance angle; • D – an additional 9° light load advance (‘D’ indicates 9°, with each g/kWh αz SPECIFIC FUEL CONSUMPTION 580 20° 540 500 30° 460 40° 420 50° 380 340 g/kWh 50° 12 40° 10 30° HC EMISSIONS 8 additional alphabet placing from ‘B’ meaning another 3°); • 10 – ignition timing retard angle under boost (when using a turbo or other supercharger). The resultant ignition timing map is not intended to be the final product but it provides a good starting point for subse­quent tuning. An example of the type of timing map produced with this system is shown in Fig.5. It is for all loads, from -100kPa manifold pressure to more than +100kPa boost at 4000 RPM on a turbocharged engine. The arbitrary reduction under boost condi­tions provided by the QuickMAP is readily apparent; this sudden step would be smoothed in due course by the operator to provide an ignition advance which varied more in keeping with the actual turbocharger boost pressure. Incidentally, like almost all pro­ grammable engine management systems, the Haltech approach uses a MAP (manifold absolute pressure) sensor to determine load, rather than an airflow meter. The production of an ignition map for the Haltech system takes only a few moments, while for some programmable systems several hours would need to be spent programming each load site. Interestingly, when using a chassis dynamometer to tune this Haltech system on a Nissan FJ20 turbocharged engine, the author and mechanic Paul Keen found detonation intruding at about 2000 RPM on 25kPa boost. A revised QuickMAP incorporating 15° of boost retard (versus the original 10°) cured the prob­lem, with the speed of the remedy impressive. Another programmable engine management manufacturer gives an example of a ‘very basic’ ignition advance curve. Advanced Engine Management Systems (manufacturer of the Wolf 3D system) provides a table of ignition advances and engine speeds. It looks, in part, as shown in Table 1. The reason for the timing being more advanced at 500 RPM than at 1000 RPM is to provide a stable idle speed. This occurs because if the engine starts to slow down from its designated idle setting, the greater ignition advance causes the engine to produce more torque, thereby increasing the engine speed back to its correct value. Tuning ignition maps Given that incorrect timing can cause major engine damage or at the least degrade performance, the tuning Table 1: Basic Ignition Timing Advance RPM 500 1000 1500 2000 2500 Advance 10° 8° 12° 15° 17° 20° 6 4 2 0 0.7 0.8 0.9 1.0 1.1 AIR RATIO λ 1.2 1.3 1.4 Fig.1: the ignition timing which gives the best hydrocarbons emissions also gives the worse specific fuel consumption. Devis­ing an ignition map which is optimal depends on the engine’s application. (Bosch) 50° b 40° 30° ADVANCE ANGLE AFTER TDC BEFORE TDC The use of a chassis or engine dynamometer allows the best tuning of the ignition map. Torque output, exhaust gas analysis and combustion temperature can all be monitored. αz a 20° d 10° 0° c 10° 20° 0 1000 2000 ENGINE SPEED 3000 REV/MIN Fig.2: retarding the ignition timing to after TDC is useful for reducing exhaust emissions. In the above graph, ‘a’ is the timing curve for full load, ‘b’ is for part load, ‘c’ is at idle and ‘d’ is when the vehicle is overrunning the engine. (Bosch) of the ignition map is critical. Most people programming engine management sys­tems use a chassis dyna­ mometer, where power and torque readings at the driving wheels can be measured. Others use an engine dynamometer which requires the engine to be removed from the vehicle for the initial tuning. Depending on the quantity and quality of the instrumenta­tion available, exhaust gas analysis, combustion temperatures, torque output and other factors may be measured, or the ignition October 1995  5 ever, because the most common use of programmable engine management is in motor sport or road-performance applications, most systems are set up for maxi­mum power combined with good driveability. Paul Keen is another mechanic who is well-used to setting up ignition timing systems. Over years of tuning mechanical advance systems on a chassis dyno, he has developed several rules of thumb which provide starting points for further refinement. Generally, he finds that, on 4-cylinder engines, a total advance of 36° is appropriate, with 32° total being used on sixes. The variation with V8s is wider, any­ where from 28-36° being used, depending on the engine and its state of tune. The variation relates more to combustion chamber design than any other factor: 4-cylinder engines (especially in the past) are better in this area than the larger engines. Turbocharged engines require ignition retard when on boost and lots of advance when at part loads. This previously difficult task is eased by the use of programmable ignition systems. tuning may be carried out using just the operator’s ears to listen for knocking. No ignition map is ever perfect and so the operator’s skill plays a large part in setting the optimum timing for the engine’s particular application. For example, the ignition timing map which gives the best results for fuel consumption is not the best for NOx emissions. In addition, a map designed to give maximum power with higher octane fuel will have poor knock-resistance if used in a vehicle subjected to varying fuel quality. How- Idle speed advance The appropriate idle advance relates more to the engine compression ratio than to any other factor, suggests Adam Allan. Engines with a IGNITION ANGLE °BTDC 40 LO AD RPM SIG NA L D E SPEE ENGIN 0 IGNITION ANGLE °BTDC IGNITION ADVANCE 35 30 25 90 20 80 15 70 10 60 5 50 40 AD RPM SIG NA L E 0 ENGIN SPEED Fig.3: these are Bosch Motronic ignition maps. The top is for premium fuel, while the bottom map is for regular fuel. While virtually identical in the low-load range, at higher loads the ‘premium’ map uses more advance. (Bosch) 6  Silicon Chip 0 7500 6500 10 7000 5500 20 6000 RPM LO LOAD 30 4500 5000 3000 3500 4000 0 Fig.4: part of an ignition map from a 418kW (560 bhp) Group A Holden V8. The advance is highest at low loads and RPM. Note the required ‘peaks’ and ‘valleys’ as a result of tuning the engine on a dynamometer. Fig.5: the QuickMAP facility of Haltech programmable engine management allows the production of ignition maps with the input of just an 8-digit code. This provides the starting point for further modifications. Fig.6: this Haltech ignition curve is for 3000 RPM on a tur­bocharged engine. Each of the individual bars on the curve can be raised or lowered to give timing changes at each load site. Fig.7: this correction chart allows the ignition timing to be changed on the basis of coolant temperature. Note the increase in timing advance at low temperatures and the decrease when the engine is overheating. Fig.8: this correction chart allows ignition retard to be pro­grammed for when induction air temperatures are high. This is especially required in a turbocharged car which does not have effective intercooling. compression ratio of 8:1 will accept an ignition advance of anything from 0-20° without kickback on star­ting. A 10:1 compression ratio will reduce this to 15°, 11:1 to around 10-12°, while race engines using the very high compression ratios of 12:1 or 13:1 can sometimes tolerate no ignition idle advance at all. The rate at which the timing advances from the static (or idle) timing is another variable. “Some engines like an early full advance and others don’t”, said Paul Keen. “The Falcon cross-flow six, for example, pings with an early full advance.” Adam Allan suggests that the point at which maximum timing ad­vance is reached should correspond to the RPM at which the wide-open throttle engine’s torque output has started to decline. If exhaust gas temperature readings are being made, he suggests that optimal ignition timing is that which gives the lowest exhaust gas temperature combined with timing advanced sufficiently to give maximum torque. A 2-3° retard of the advance angle from the point of detonation provides a sufficient safety margin, he believes. At light loads, as used in everyday cruise conditions, an advance of up to 40° will improve responsiveness and economy. This figure is greater than generally used by tradition­al mechanically controlled timing systems but is easily achievable with programmable ignition. Adam Allan has seen this advance used successfully on many engines, even those with an 11:1 com­ pres­sion ratio and running on Avgas. Examples of ignition maps While programmable ECU ignition maps are the result of many hours spent using dynos and so are intellectual property worth thousands of dollars, we managed to find two sources prepared to reveal some of this information. Paul Keen of Adelaide’s Dar­l­ing­­ton Auto Tune allowed access to Haltech E6 software maps devel­ oped for a turbocharged FJ20 2-litre Nissan engine, while Craig and Adam Allan released ignition maps written using Autronic SMII software for a Holden Group A racing V8 and for a Ford 289 V8. Fig.4 shows the ignition advance map for 3000-7500 RPM of the Group A V8. Using a 10:1 compression ratio and a high octane fuel, a maximum power output of 418kW at 7100 RPM was measured. As expected, the advance at low loads remains high (at 40°) until 5000 RPM but drops to just 5° at 7500 RPM. Low loads at 7500 RPM would simply not be seen in this October 1995  7 occurs under positive manifold pres­ sure; ie, when boost is provided by the turbo. Fig.7 shows a correction chart based on coolant tempera­ture. Up to 10° of advance or retard can be used to modify the map developed on the basis of load and RPM. While this map shows no modification of the timing for the temperatures which would be realised in normal running, the height of these bars can all be changed – meaning that ignition timing can be modified on the basis of coolant temperature with great resolution, if desired. The second of the Haltech ignition correction charts (Fig.8) has even more potential, especially in turbo engines. Turbochargers heat the intake air as they compress it and a hot induction charge is much more likely to cause detonation than one at ambient temperatures. Intercooling is often provided to reduce the possibility of detonation and to increase power. However, an ignition map which can reduce the amount of ignition advance on the basis of air inlet temperature has the potential to allow very high engine efficiencies by running boost timing which is retarded only a little – but which greatly reduces the timing advance as the air inlet temperature increases. A laptop PC, a chassis dynamometer with power and torque readouts, exhaust gas analysis equipment and a skilled operator are needed to set up programmable ignition (and fuel) ECUs. 40 35 IGNITION ADVANCE, DEGREES BTDC 30 25 20 Idle ignition curve 15 10 5 0 300 ENGINE RPM 1000 Fig.9: idle ignition advance curve, Ford 289 V8 with Autronic programmable engine management. The idle speed is made self-stabilising to some degree by the use of this low RPM timing curve. race engine and so little dyno tuning was carried out in this area. As loads increase, the ignition advance is greater at all RPM and is nothing like the curve provided by mechanical advance mechanisms. However, of greatest interest are the required peaks and troughs in this ignition map, which was developed with the engine being loaded by an eddy-current engine dynamometer and with full data logging being used. 8  Silicon Chip Incidentally, Fig.4 was drawn from the Autronic program data (which is normally expressed in tabular form) using Excel software. The ignition maps shown here for the FJ20 turbo engine are printed directly from the Haltech E6 program which uses on-screen bargraphs to show the ignition advance. Fig.6 shows a 3000 RPM ignition timing map, with load on the horizontal axis. Note the reduction in advance which Fig.9 shows the idle ignition curve for a 289 Ford V8 with Autronic programmable engine management. The car uses an automat­ ic transmission and does not have an air idle-speed control valve, meaning that idle speed control when the car is placed in and out of ‘drive’ is carried out mostly by ignition control. The 300 RPM advance of 12° is for starting while the 34° advance at 450 RPM helps bring the engine back up to idle speed when sudden loads are placed on it. The advance of only 5° at 1000 RPM helps slow the engine, bringing it back to the correct idle SC RPM. Acknowledgements Thanks to Allan Engineering (085) 22 1901 and Darlington Auto Tune (08) 277 4222, both of Adelaide, SA, for their assistance in the preparation of this article. SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.irtcommunications.com/ October 1995  9 CIRCUIT NOTEBOOK 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. +5V FROM RECEIVER POSITIVE SIGNAL 0V 47  IC1a 4070 4.7k 1 NEG 2 0.1 14 7 10 15k 3 .01 S1 POS 0.1 +5V 5 D1 1N914 IC1b D2 1N914 6 47k 3 4 D4 1N4004 +5V 22k D3 1N914 .022 CS1 LM334 DISCHARGE SLOPE VR2 5k 20k Speed controller for small motors in models This speed controller can be used to drive small motors in model R/C applications. The circuit consists of two ICs: a quad XOR gate (4070) and a dual op amp (LM358). It is powered from the receiver’s battery via the servo lead. Pulses from the receiver are fed via a 4.7kΩ resistor to pin 1 of IC1a which acts as either an inverting or non-inverting buffer stage, depending on the position of S1. For positive pulse receivers (eg, JR, Futaba, etc), pin 2 is switched low. The rising edges of the buffered 1-2ms pulses on pin 3 are differentiated using a .01µF capacitor and a 47kΩ resistor and the negative portion of the waveform is clipped by D1. This signal is then fed to pin 5 of IC1b. Each time the voltage on pin 5 exceeds ½Vcc, pin 4 of IC1b goes high to give a series of 10  Silicon Chip R 47k .022 9 IC1c 10 8 S2 B1 5 6 1 MOTOR .047 51k DEAD BAND ADJ VR3 20k 22k 8 IC2a 2 LM358 4 PULSE WIDTH VR1 20k 10k IC2b narrow pulses. Each of these pulses rapidly charges a .022µF capacitor via D2, with the capacitor then slowly discharging via a parallel 47kΩ resistor in between pulses. The resulting sawtooth waveform is then compared in IC2a with a preset reference voltage on pin 2. VR1 adjusts this reference voltage so that IC2a outputs a 1ms pulse train. The pulses from IC1a & IC2a are compared by IC1c. When these pulses are in-phase and of equal duration, pin 10 of IC1c remains low. However, when the number of receiver pulses increases (stick forward), a difference pulse appears at IC1c’s output. Thus, depending on the control stick position, the pulses on pin 10 of IC1c may vary in width between 0 and 1ms. These pulses must be stretched in order to drive the motor. This is achieved by producing another sawtooth voltage with variable DC shift and comparing it with another 7 560  Q1 TIP142 reference voltage in IC2b. In this case, the sawtooth voltage is produced by charg­ ing a .022µF capacitor via D3 and discharging it via an adjust­able current source based on an LM334. This ensures that the capacitor ramps down in a linear fashion. The reference voltage on pin 6 of IC2b is adjusted (using VR3) to about 1.2V, giving a deadband (off) for the first 20% of stick travel. The pulse width at the pin 7 output then increases from that point until the stick is fully forwards. This output drives Darlington transistor Q1 which then pulses the motor on and off at about 50Hz (20ms). Q1 can handle loads up to 120W if properly heatsinked. A 1A diode is connected across the motor to protect the transistor from back-EMF. Trimpots VR1-3 are adjusted using an oscilloscope. Manfred Schmidt, Edgewater, WA. ($35) D1-D4 4x1N4002 Adding tail lamps to guard’s vans 100k IC1a 74HC02 3 470 16VW 330 LED1 11 1 100k 8 IC1b 5 10 6 9 At the same time, pin 4 of IC1d will be at +5V and so LED 2 will be extinguished. When the track polarity changes (eg, when the lo-  13 IC1c LED2 IC1d  4 7 comotive is reversed), LED 2 lights and LED 1 turns off. Stephen Ives, Tamworth, NSW. ($20) POWER SOCKET EDGE OF PCB +5V +5V REGULATOR 7805 14 12 2 GND Looking for a low-cost stepping motor and a controller? Surplus 5.25inch floppy disc drives are cheap and the stepper motors that control head movement in these drives can be adapted to a variety of uses. What’s more, the controllers for these drives are easy to use. All that one has to do is remove the PC board and stepper motor from the drive, connect them together, and connect the PC board to the “outside world”. The only connections required are to a suitable power supply plus four connections to the interface socket. These latter four connections control the motor. The procedure is as follows: (1). Connect the ground (0V return) to any of the odd numbered pins; (2). Connect a lead to pin 14 if the disc drive was drive 1, or to pin 12 if it was drive 2. This is “drive select” and is necessary for the drive logic to be selected; (3). Connect a lead to pin 18. The logic on this pin determines the step direction; ie, high = step out, low = step in. This works in conjunction with pin 20 (the step input); (4). Connect a lead to pin 20. This is the “step” command; a logic low on this pin will make the motor step. Because the logic is normally high ZD1 5.1V 400mW 100 25VW GND Low-cost stepper motor & controller 1k TRACK +12V This circuit is for adding tail lamps to guard’s vans on model railways. It provides directional control for the lights which can be added using high intensity red LEDs with 1mm optical fibre links. D1-D4 provide a positive voltage to the 100µF ca­pacitor regardless of the track polarity. The 1kΩ resistor limits the current to ZD1, which then provides 5V for IC1. When the upper track input is positive, pin 9 of IC1b will be positive and thus pin 10 will be at ground. This means that both inputs of IC1a will be at ground and so its output (pin 1) will be at +5V. IC1c inverts this high and so LED 1 will light via the 330Ω resistor. I GO 7805 MOUNTED FACE DOWN and the various signals are active low, the motor can be controlled using transistors, switches or relays. Note that the drive will ignore signals on the inter­face unless its drive select pin is low. It is possible to control up to four motors at once using a parallel set of control leads, simply by switching the drive select pins. Finally, the drive will require +12V and +5V rails. The way around this is to use a +12V 1A supply and derive the +5V rail using a 7805 3-terminal regular. The diagram shows how this is done. The input of the regulator goes to the +12V connection on the power socket, the ground pin to either of the two ground connections, and the output to the +5V connection. Jeff Allen, Canberra, ACT. ($30) Pin Assignments For Floppy Disk Connector Ground Signal Description 1 2 Reduced write current/rpm 3 4 NC 5 6 NC 7 8 Index 9 10 Motor on 1/drive select 3 11 12 Drive select 2 13 14 Drive select 1 15 16 Motor on 2/drive select 4 17 18 Direction select 19 20 Step 21 22 Write data 23 24 Write enable 25 26 Track 00 27 28 Write protect 29 30 Read data 31 32 Head select 33 34 Disc change SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: dicksmith.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: dicksmith.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: dicksmith.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: dicksmith.com.au Monitor radioactivity with this compact GEIGER COUNTER Are you are concerned by the Nuclear tests in the Pacif­ic and in China? Worried about a possible increase in the amount of background radiation? Then check it out with this Geiger counter. It will detect alpha, beta and gamma radiation and has an audible output. By JOHN CLARKE Most people have never used a Geiger counter but they would probably have seen them in old war movies. These showed people in full protective suits sweeping an area with a rather large “high tech” contraption that produced loud clicking when a source of radiation was detected. Our Geiger counter does the same job and produces audible clicks at a rate dependent on the amount of radioactivity. However, it is much more compact and does not require the obligatory carry handle used on the instruments of the past. What is radioactivity? Radioactivity is the emission of energy or particles due to the spontaneous decay of an unstable nucleus of an element to a lower energy state. Atoms of all elements have a nucleus comprising one or more protons and neutrons plus outer shells of electrons. The number of protons in the nucleus is referred to as the Atomic Number 10000 NEON + HALOGEN GAS ANODE CATHODE STAINLESS STEEL SHELL CENTRAL WIRE Fig.1 (above): cross section of the Geiger Muller tube. The passage of an alpha or beta particle or a gamma photon causes the tube gas to ionise and produces a brief discharge. Fig.2 at right shows the response characteristic of the Geiger tube to radia­tion. It is limited by the tube “dead time” to about 10,000 counts/second. 16  Silicon Chip COUNTS/SECOND GLASS MICA WINDOW and this determines the basic element properties. While most atoms of an element will have a fixed number of neutrons, some can differ and these are called isotopes. Most isotopes are unstable and all isotopes above Bismuth (Bi) with an Atomic Number of 83 are unstable. An unstable isotope will spontaneously decompose and emit radioactive energy which is far greater than the energy changes normally associated with chemical reactions. Radioactiv- 1000 100 10 .001 .01 0.1 RADS/HOUR 1 10 100 +9V V+ i2 S1 GND Table 1: Radiation Effects D1 L1 C1 i1 Fig.3: the basic circuit of a DC-DC boost converter. Each time S1 opens, the energy stored in L1 is dumped into C1. ity com­ prises alpha particles, beta particles, gamma rays, fast neu­trons, positrons, photons or a combination of these. Alpha particles are positively charged particles which are identical to Helium nuclei; ie, they comprise two protons and two neutrons. These particles can cause a large amount of tissue damage but fortunately they do not travel very far in air. In fact, alpha particles must have an energy of greater than 6MeV before they can travel 45mm. MeV stands for million electron volts and is a measure of the energy of the particle. As an example, the Americium alpha particle source used in most smoke detectors only has a range of 20mm or so before all the particles are stopped by collisions with the air. The alpha particles are further restricted by the fine particles of smoke and this is the principle of operation of smoke detectors. We’ll talk a little more about smoke detectors later but readers should note that provided a smoke detector is not disassembled Dose (Rems) Effect 0-25 None 25-50 White blood cell count reduced slightly 50-100 High reduction in white blood cell count 100-200 Nausea, hair loss 200-500 Bleeding, likelihood of death 500+ Fatal it emits no alpha particles at all; they are all confined within the metal chamber. Beta particles are electrons. Electrons with energies over 1MeV lose a lot of energy by producing continuous X-rays. Gamma rays are high energy photons (electromagnetic waves) with a very short wavelength (.0005nm to 0.1nm). These photons are difficult to stop unless very thick lead or concrete barriers are placed in their path. The Positron is a positively charged particle with the same mass as an electron. at varying ex­posures, measured in rems. Geiger counter circuit The heart of a Geiger counter is a Geiger Muller tube which is essentially an ionisation detector. Its cross section is shown in Fig.1. It comprises a metal case with a mica window at one end and a glass insulating seal at the other. A thin wire is located in the centre of the case and a high voltage of around 500V is applied between this (Anode) and the metal case (Cathode). When a radiation particle or photon enters the tube via the mica window, it ionises the gas and this creates a discharge. After each discharge, the tube is Biological effect The total biological effect of radiation is measured in rems which stands for “Roentgen Equivalent in Man”. This is found by multiplying the number of rads (absorption of .01 joules per kilogram of tissue) by a factor of 1 for beta, gamma and X-radiation and by 10 for alpha and other high-energy neutron sources. Table 1 shows the effects of radiation POWER S1 WARNING! This circuit includes a 500V supply which can cause an electric shock. Avoid contact with the circuit compon­ents when power is on. 2x1N4936 D1 D2 100 16VW +500V 1.8k 9V T1 100 16VW 100k 8 5 A  LED1 K IC1a 6 LM358 C1 100 16VW 7 100k 10k 20T 3 2 IC1b 1 470k 200T Q1 MTP3055E D G S 6.8k GEIGER MULLER TUBE .0015 4.7M K GD S E C VIEWED FROM BELOW 8W 4.7M A 4.7M DETECTOR 6 K 560k OSCILLATOR 500V ADJ VR1 50k B A 4.7M CONVERTER ERROR AMPLIFIER 100k .01 2kV 0.1 2 4 Q2 BC328 8 IC2 7555 3 B E C 1 SCHMITT TRIGGER GEIGER COUNTER Fig.4 (below): the full circuit of the Geiger Counter. IC1 and Q1 step up the battery voltage to 500V DC for the Geiger tube. Each time the tube discharges due to the passage of a radioactive particle or photon, IC2 and Q2 produce a click in the loudspeaker. October 1995  17 Inside the case of the Geiger counter. Note that the corners of the PC board must be filed to fit it into the case. The 9V battery sits on top of a small foam cushion and is held in place when the lid of the case is attached. not immediately sensitive to further ionising radiation until the gases have reverted to their normal de-ionised state. This period of insensitivity is called dead time and it sets a limit on the number of discharges per second. In the Geiger Muller tube used in our circuit, the dead time is typically 90 microseconds and this limits the maxi­ mum number of detectable discharges to about 10,000 per second. Fig.2 shows the rad­ia­tion response of the tube. The horizontal axis shows the level of radiation while the vertical axis shows the number of discharges per second. Note that radiation sources are typically random in nature, so the Table 1: Radiation Effects Natural Sources (Millirems/Year) Cosmic 50 Earth 47 Buildings 3 Air 5 Internal human tissue (potassium isotopes) 21 Man-Made Sources (Millirems/Year) X-ray machines 50 Radioisotopes 10 Luminous watch dials, TV tubes 2 Radioactive fallout during nuclear tests 1 PRIMARY START (20T, 0.25mm ENCU) 2 PRIMARY FINISH 8 SECONDARY START 7 (200T, 0.25mm ENCU) 6 3 SECONDARY FINISH 5 4 T1 WINDINGS VIEWED FROM BELOW Fig.5: here are the winding details for the step-up transformer. Note that the two windings are both wound in the same direction. 18  Silicon Chip 4-30 audible output from the Geiger counter is just noise. At low radiation levels, it produces random clicks and as the radiation level is increased, the clicks become more rapid but still quite random. At much higher radiation levels, the clicks merge into noise with a rather “spitty” quality. The Geiger Muller tube requires a high voltage supply of around 500V DC. To provide this we step up the supply from a 9V battery. Fig.3 shows how this is done using a boost converter. Initially, S1 is closed and current builds up in inductor L1. The inductor current is i1. When S1 is opened, inductor current i2 passes via diode D1 to charge capacitor C1. The actual voltage developed depends on the inductance of L1, the length of time that L1 is charged (ie, for the current to build up) and the load current drawn from C1. By the use of a feedback circuit, the voltage across C1 can be set to the re­quired level. Now refer to the full circuit for the Geiger counter in Fig.4. The step-up arrangement differs from that in Fig.3 in that the inductor is a transformer with two windings and a Mosfet transis­tor (Q1) is used as the switch. The advantage of using a trans­former with a higher voltage secondary is that we can use a readily available 60V Mosfet rather than a more expensive 600V type. Q1 is switched on and off at a rate of about 10kHz by op amp IC1b which is connected as a Schmitt trigger oscillator. IC1b operates by successively charging and discharging the .0015µF capacitor at its pin 2 via the 6.8kΩ resistor from its output at pin 1. Each time Q1 switches off, it produces a high voltage (ie, many times the 9V supply) pulse across the primary of transformer T1. The transformer steps up the primary pulses by a factor of 10 in its secondary and the resultant output is fed via diodes D1 & D2 to a .01µF 2kV capacitor. Regulating the output While the circuit described so far will certainly develop a high DC output, the actual voltage will tend to vary widely, depending on the input DC voltage and the load current drawn by the Geiger Muller tube which will itself vary widely, depending on the amount of radiation present. To set the DC output close to 500V we need 100k 470k 100uF IC1 LM358 GEIGER MULLER TUBE .0015 100k 6.8k 1 560k 10k VR1 100k 4.7M Q1 D1 D2 T1 1 100uF 4.7M 1 IC2 7555 4.7M 4.7M a negative feedback circuit and this is provided by op amp IC1a which functions as an error amplifier. IC1a monitors the DC output of the boost converter via a voltage divider consisting of two 4.7MΩ resistors in series, trimpot VR1 and the 100kΩ resistor to pin 6. IC1a compares the DC voltage at its pin 6 with the reference voltage at its pin 5, provided by the 1.8V voltage drop across light emitting diode LED1. IC1a amplifies the difference between the two and its output is used to vary the threshold voltage of the Schmitt trigger oscillator, at pin 3 of IC1b. Hence, if the DC output voltage is higher than it should be, IC1a increases the voltage at pin 3 and the result is that the pulses fed to Q1 are slightly reduced. This reduces the output voltage. Conversely, if the DC output voltage is a little low, due to extra drain or a lower battery voltage, IC1a lowers the threshold voltage at pin 3, lengthening the pules to Q1 and thereby increasing the output voltage to what it should be. C1, the 100µF 16VW capacitor across LED1, is there to prev­ e nt overshoot of the high voltage DC at switch-on. Two fast recovery diodes, D1 & D2, have been used in series at the secondary of T1 because the breakdown voltage for each diode is only 500V. By using two diodes in series we get an adequate safety margin. Normally though, to ensure equal voltage sharing, the diodes should each have a high voltage resistor (eg, 1MΩ) across them. However, in this circuit, the impedances are so high that we are relying on the internal leakage of the diodes to provide adequate voltage sharing. The 500V supply is applied to the Geiger Muller tube via two 4.7MΩ resistors in series. When the tube SPEAKER .01 2kV 0.1 Q2 1.8k 9V BATTERY A LED1 S1 100uF Fig.6: follow this component layout diagram when installing the parts on the PC board. The Geiger Muller tube is held in place with wire straps. Fig.7: this is the full size etching pattern for the PC board. Check your board carefully before mounting any of the parts. detects radiation, its impedance drops sharply and a brief pulse appears across the 560kΩ cathode resistor. This pulse is fed to IC2, a 7555 wired as a Schmitt trigger. It can be thought of as a pulse buffer, between the high impedance of the 560kΩ cathode resistor and the low impedance of the base of transistor Q2. Thus each time the Geiger tube discharges, IC2 delivers a brief pulse to Q2 which drives the loudspeaker to produce an audible click. Power for the circuit comes from a 9V battery via switch S1. When the switch is off it connects the circuit’s positive supply rail directly to the 0V rail. This discharges C1, the capacitor across LED1, so that the circuit will start slowly when power is reapplied. Assembly All the components are mount­ed on a PC board coded 0431­0951 and measuring 56 x 104mm. The component overlay is shown in Fig.6. Begin construction by checking the PC board for any breaks or shorts between tracks. Also the corners of the PC board will need filing so that TABLE 3: RESISTOR COLOUR CODES ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ No. 4 1 1 3 1 1 1 Value 4.7MΩ 560kΩ 470kΩ 100kΩ 10kΩ 6.8kΩ 1.8kΩ 4-Band Code (1%) yellow violet green brown green blue yellow brown yellow violet yellow brown brown black yellow brown brown black orange brown blue grey red brown brown grey red brown 5-Band Code (1%) yellow violet black yellow brown green blue black orange brown yellow violet black orange brown brown black black orange brown brown black black red brown blue grey black brown brown brown grey black brown brown October 1995  19 The Geiger tube is secured to the PC board with a couple of wire straps over the body, as shown here. The third wire at the end of the tube is the cathode connection. Note the use of “O” rings at the mica window end of the tube. direc­tion shown and wrap a layer of insulating tape around this. Make sure that the tape does not start or finish on the sides of the former since this will prevent the cores sliding onto the bobbin when winding is completed. Continue winding and apply one thickness of insulating tape over each layer. After 200 turns, terminate the end of the wind­ing into pin 3. The primary is started on pin 1 and after 20 turns finished on pin 8. It must be wound in the direction shown. There will not be sufficient room for a layer of insulating tape on this primary winding. The transformer is assembled by sliding the cores into each side of the bobbin and securing the clips. This done, solder the transformer to the PC board, making sure that it is oriented correctly. Circuit testing it will fit into the case. The required shape is shown on the copper side of the PC board. This done, start the board assembly by installing the PC stakes. These are located at the + and (-) battery input points and the loudspeaker outputs. Three PC stakes are also placed in the holes for switch S1 so that it will be raised from the PC board. Next, install the two wire links (one near Q1 and the other next to S1), then install all the resistors, using Table 3 to guide you with the colour codes. This done, insert the diodes and ICs, taking care with their orientation. The capacitors are next, followed by Q1, Q2 and trimpot VR1. LED1 is mounted using the full length of its leads so that it will protrude through the front panel. It is a good idea to fit plastic sleeving over one of the leads, to prevent shorts. Switch S1 is soldered on the top of the PC stakes. Do not attach the Geiger tube yet! Transformer winding Transformer T1 is wound with 0.25mm enamelled copper wire as shown in Fig.5. The secondary is wound first. Strip back the insulation on one end of the wire and terminate it on pin 7 of the bobbin. Now wind a layer of turns side by side in the Tube Specifications Gas content .................................................................. Neon & halogen Operating temperature ................................................. -40°C to +75°C Wind trimpot VR1 fully anticlockwise, connect the bat­tery leads and switch on. The LED should light and the trans­former should emit a high pitched whistle. Take care not to touch the circuit because of the high voltage it produces. Select the 1000VDC range on your multimeter. Attach the negative lead to the (-) battery terminal on the PC board and the positive lead to the cathode (striped end) of D2. Adjust VR1 for a reading of about 500V. Disconnect the battery and connect the Geiger tube to the PC board. The tube is secured using tinned copper wire straps over the body, while its cathode lead is soldered to a pad adjacent to pin 1 of IC1. The anode connection is made using a short length of tinned copper wire to a pad near the cathodes of D1 & D2. Avoid using excess heat on the anode terminal when soldering. Window material ........................................................... Mica Case Recommended anode resistor ..................................... 10MΩ The unit is housed in a plastic case measuring 64 x 114 x 42mm. One end of the case needs a 19mm hole drilled for the Geiger tube. We used two 18mm OD “O” rings to support the tube and provide shock relief. One “O” ring is fitted over the groove at the mica window end. The other is placed over the section of the tube where it just protrudes from the end of case. The board is mounted in the case using four 3mm screws at the corners. Starting voltage ............................................................ 325V Recommended operating voltage ................................. 500V Operating voltage range ............................................... 450-600V Minimum dead time ...................................................... 90µs Minimum alpha particle energy for detection ................ 2.5MeV Minimum beta particle energy for 25% absorption in mica window ............................................... 30MeV 20  Silicon Chip PARTS LIST This photo shows the internal construction of two typical smoke detectors. Both have a detection chamber with a minute amount of the radioactive isotope Americium 241. The detector on the left has the cover of the smoke chamber removed to reveal the centrally placed alpha particle source. The Geiger Counter will only detect radiation when it is brought very close to this alpha source. This is because the alpha particles will only penetrate a very short distance in air. Fix the label onto the lid and drill holes for the switch and LED 1, plus mounting holes for the small loudspeaker. Holes are also drilled in the radiation symbol to let the sound from the loudspeaker escape. Attach the loudspeaker with two small self-tapping screws and wire it to the PC board using the twin rainbow cable. We used a small strip of foam plastic glued to the PC board directly under the battery to prevent it rattling in the case. Finally, assemble the case and apply power. The Geiger tube should fire once every few seconds and sound the speaker. This is the background radiation. Any radiation greater than background will provide a much faster repetition sound. Radiation source GEIGER COUNTER + + POWER Fig.8: the full size artwork for the front panel label. If you want to test your Geiger counter with a much higher intensity than background radiation, you can use the radiation source inside a smoke detector. This consists of a small amount of the radioactive isotope Americium 241 (equivalent to 0.9 mi­crocuries). This has a half-life of 400 years so it is pretty constant over a human lifetime. To use the Americium alpha particle source, you need to remove the internal aluminium cover from the smoke detector’s PC board. This needs to be done otherwise no alpha particles escape. With the central alpha particle source exposed, bring the window of the Geiger counter close to it. Virtually nothing happens until the Geiger tube window is within 20mm of the alpha source. Then as you bring it closer, it will begin to click rapidly and then produce more and more noise with a rising pitch as you place the source as close as possible to the window. 1 PC board, code 04310951, 56 x 104mm 1 plastic case, 64 x 114 x 42mm 1 Dynamark label, 55 x 103mm 1 LN712 Geiger Muller tube (from Jaycar Electronics) 1 square 30mm 8Ω loudspeaker (Altronics Cat. C-0606) 1 SPDT toggle switch (S1) 1 9V battery and battery clip 1 Philips EFD20 transformer assembly (T1): 2 4312 020 4108 1 cores 1 4322 021 3522 1 former 2 4322 021 3515 1 clips 1 8-metre length of 0.25mm enamelled copper wire 1 50mm length of twin rainbow cable 1 100mm length of 0.8mm tinned copper wire 7 PC stakes 4 3mm screws 2 self-tappers for loudspeaker 2 “O” rings 15mm ID x 18mm OD 1 50kΩ horizontal trimpot (VR1) Semiconductors 1 LM358 dual op amp (IC1) 1 7555, TLC555, LMC555CN CMOS timer (IC2) 1 MTP3055E N-channel Mosfet (Q1) 1 BC328, BC327 PNP transistor (Q2) 1 3mm red LED (LED1) 2 1N4936 fast recovery diodes (D1,D2) Capacitors 3 100µF 16VW PC electrolytic 1 0.1µF MKT polyester 1 .01µF 2kV ceramic 1 .0015µF MKT polyester Resistors (0.25W 1%) 4 4.7MΩ 1 10kΩ 1 560kΩ 1 6.8kΩ 1 470kΩ 1 1.8kΩ 3 100kΩ This highlights the fact that the alpha particles penetrate only very short distances in air. After you have made the test, reassemble the smoke detec­tor, test it and reinstall it so it can provide you with SC ongoing protection against fire. October 1995  21 Build these 3-way Bass Ref lex Loudspeakers 22  Silicon Chip Here is the loudspeaker for those who don’t want to be bothered with small unobtrusive boxes. This is a large tower design which can’t be hidden. You’ll need a large room for a pair of these speakers but the reward will be really great sound and lots of power handling, with a 10-inch driver providing the bass reproduction. By LEO SIMPSON F OR THE POWER HUNGRY au- dio enthusiast, a 10-inch woofer in a large cabinet is equivalent to a thumping great V8 to a lead-footed petrol head. This speaker really performs, with prodigious power handling and beautiful bass down to below 30Hz. But as well as power handling and extended bass response, this system is very satisfying in its handling of all types of music, with a smooth mid­ range and very clean treble reproduction. Lest you become overly concerned about how much space is taken up by two of these cabinets, they actually take up no more floor space than typical compact two-way loudspeakers mounted on stands. They are big but they are only marginally larger than the JV60 design we featured in the August 1995 issue. The dimensions are 320mm wide, 920mm high and 315mm deep, including the thick­ness of the grille cloth frame. The cabinets are made of 16mm veneered particle board, internally braced and with an enclosure volume of about 64 litres. As with the JV60’s previously featured, this design was produced exclusively for Jaycar Electronics by Australian Audio Consultants, PO Box 11, Southport, SA 5410. This is a 3-way design, featuring two ferrofluid-cooled tweeters, the same as the single tweeter in the JV60, together with two midrange drivers and a 10-inch woofer. The full circuit is shown in Fig.1. It shows a October 1995  23 repeatedly over-driven otherwise the performance of the Polyswitches will be prejudiced. Two Vifa D25AG-35-06 tweeters are connected in series to cover the treble range above 3kHz, as determined by L1 and C1. Two Vifa P13WG-00-08 drivers cover the midrange frequencies from 500Hz to 3kHz, as set by L2, C2 and L3. R1 & C3 provide im­pedance equalisation for the midrange drivers so that they present a more “resistive” impedance to the filter components and thus ensure that steeper attenuation slopes are achieved. A single Vifa M26WR 10-inch woofer is used for the bass frequencies and it is coupled via L4 and C4. Again, impedance equalisation is provided by R2 and C5. Nominal impedance for the complete system is 8Ω. The overall impedance characteristic is shown in Fig.3. This shows the classic double hump of a bass reflex design, with the minimum impedance of 7Ω occurring at about 120Hz. 10-inch woofer When you unpack the boxes, each enclosure will look like this. The moulded port tubes are hanging in the enclosure bracing panel. They need to be removed, the baffle glued in place and then the speakers can be installed. Not shown is the grille cloth frame which is supplied in finished form. conventional 3-way crossover net­ work with attenuation slopes of 12dB/ octave. Note that the treble, midrange and bass filter networks each have Poly­switch PTC ther­mistors, giving comprehensive protection against overdrive. Normally, these Polyswitch PTC thermistors have a very low resistance and therefore have a minimum effect on the signal fed to the drivers. However, when the signal current exceeds a criti­ cal threshold, the Poly­ switch 24  Silicon Chip suddenly goes virtually open cir­cuit and thus prevents the loudspeaker from overdrive. After a short period which depends on the initial overload, they revert to their low resistance state and the signal is once again con­nected to the drivers. As noted in the JV60 article, Poly­ switches are there solely to provide insurance against overdrive or as far as the woofer is concerned, against catastrophic DC faults in the power ampli­fier. The speakers should not be The heart of this design is the Vifa woofer. It has a large cast magnesium basket and the very stiff paper cone has a syn­thetic rubber roll surround. The voice coil diameter is 50mm and the effective cone area is 337 square centimetres. The free-air cone resonance is at 26Hz and the frequency coverage is up to 1kHz. Its sensitivity is 88.5dB and nominal power handling is 160 watts. Peak power handling is an impressive 500 watts. The 64-litre enclosure has two 66mm plastic ports 200mm long. The two midrange drivers are housed in their own sealed plastic enclosures which stop their cones from being pumped back and forth by the woofer. One of the big attractions in building this kit is that there is virtually no carpentry required. The pair of cabinets is supplied finished except for the front baffle which has to be glued into place. If you want to build your own cabinets, that is certainly an option and we have given full construction details in the diagram of Fig.2. Note that you can vary the cabinet dimensions slightly if you wish but the enclosure volume must still be close to the 64 litres. Assembly Assuming that you have acquired the complete kit, the first step in the These are the Vifa drivers, crossover network and plastic mid­range enclosures provided for each speaker system. Also included are the rear terminal panel, Innerbond filling and mounting screws. C1 3.3 POLYESTER P1 RXE075 RED T1 2x D25AG T2 L1 0.8mH INPUT assembly is to glue the baffles into each speaker box. We found that our sample cabinets had become slightly out of square while in transit and so they had to be carefully pushed back square while the baffles were pushed into place. PVA glue is supplied as part of the kit and it should be run all around the rebate for the baffle before it is pushed into place. Wipe any excess glue off the front of the baffle before it dries otherwise it will be difficult to remove. Allow a good half hour or more for the glue to dry. Then the two bass reflex ports can be screwed into place. The next task is to mount the cross­over network board onto the rear panel (inside the enclosure, of course). Before you do that, identify all the wires for the various drivers; their various colours are marked on Fig.1. Mount the crossover with four screws and termi­nate the two wires to the rear GREY BLACK P2 RXE160 L2 0.8mH L3 9mH P3 RXE300 BLACK C2 15 BP YELLOW R1 10 5W C3 3.3 POLYESTER 2x P13WG M2 BLACK L4 4mH C4 3.3 POLYESTER M1 BLUE R2 6. 8  10W C5 10 BP W1 M26WR BLACK JV100 SPEAKER SYSTEM Fig.1: the JV100 is a 3-way bass reflex system with the tweeters and midrange drivers both connected in series to their respective filter networks. Comprehensive overload protection is provide by the three Polyswitch PTC thermistors. October 1995  25 Fig.2: use this diagram if you intend building the cabinets yourself. The dimensions may be varied slightly but the enclosure volume should be close to 64 litres and the shelf brace must be included. CL 20 65 785 C 252 B 590 920 (888) A 288 20 INTERNAL BRACE 4 HOLES 100 x 80 SPACED 23 APART ABOUT BRACE CENTRE 375 B C HOLE SIZES: A = 234 DIA B = 118 DIA COUNTERBORED 139 DIA x 3 DEEP ON OUTSIDE C = 86 DIA D = 77 DIA 65 85 BRACE MOUNTED 50 BELOW THE BOTTOM OF HOLE B D * D DIMENSION IN BRACKETS ARE INTERNAL ENCLOSURE BACK INSET 11 FROM REAR EDGE MATERIAL: 16 PARTICLE BOARD DIMENSIONS IN MILLIMETRES 70 70 * 295 (252) 320 (288) JV100 SPEAKER ENCLOSURE panel connector which can then be screwed into place. This panel should be mounted with the termi­nals facing down. This makes it easier to secure 26  Silicon Chip the speaker wires from the amplifier. The terminals are quite large so you will have no trouble even if you are using very thick speaker cables. Connect and solder the two wires to the tweeters. Note that an intermediate wire runs between the positive terminal on one tweeter and the negative Kit Availability Kits for the JV100 loudspeakers are available from all Jaycar Electronics stores and their dealers. Prices are as fol­lows: (1) Speaker kit – includes two woofers, four midrange drivers, four tweeters, two crossover networks, two rear terminal panels, Innerbond and mounting screws: $1179.00. (2) Cabinet kit – includes a pair of cabinets finished in blackwood veneer, complete except for the pre-cut baffles which must be mounted in place: $298.00. (3) A pair of assembled and finished grille cloth frames: $80.00. Alternatively, you can purchase the com­ plete kit for a pair of speakers for $1499.00. The crossover network uses iron cores for the two larger induc­tors, while the other two are air-cored. midrange drivers to be reversed to that of the tweeter and woofer. This normally gives the best sound quality. Again, there is an intermediate wire between the positive terminal of one midrange and the negative terminal of the other. The wires for each midrange need to be passed through the small hole in the end of the plastic enclosure. After the wires are soldered to the drivers, the access hole in each plastic enclo­sure is plugged with the supplied sealant, to make it airtight. Each midrange and its plastic enclosure is then dropped into position in the baffle and secured with four screws. Next, insert half the supplied terminal on the other. This is most Innerbond filling material into each important for phasing. enclosure. This can be loosely tacked Next to be fitted are the midrange into place. drivers. Note that while the midrange Finally, solder the remaining two drivers may appear to be incorrectly wires to the woofer and mount it on phased in Fig.1, the diagram is correct. the baffle with four screws. Do not It is conventional for the phase of the over-tighten any of the screws because it is fairly easy to strip the holes. If this happens, rotate the speaker, drill pilot holes AUDIO PRECISION IMPEDANCE (OHMS) vs FREQUENCY (Hz) in a differ­ent position and 50 re-fasten all the screws. Be very carefull when you are wielding your screwdriver during this assembly procedure. If you are careless, you could slip and damage one of the driver’s cones and that could mean an 10 expensive repair. When you have completed one loudspeaker system, hook it up to your amplifier and have a listen. If all is well, go ahead and assemble the other loudspeaker. If the sound is not quite right, check that you have connected all the speakers correctly. If the phasing is wrong, the sound can be 1 quite strange and may even 10 100 1k 10k 20k have a disembodied quality. That won’t happen to you, provided you have been Fig.3: this is the impedance plot for the JV100 speakers. We plotted a curve for each of SC the prototypes and they were virtual­ly identical. very careful. October 1995  27 SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au ORDER FORM BACK ISSUES MONTH YEAR MONTH YEAR PR ICE EACH (includes p&p) Australi a $A7.00; NZ $A8.00 (airmail ); Elsewhere $A10 (airmail ). Buy 10 or more and get a 10% discount. Note: Nov 87-Aug 88; Oct 88-Mar 89; June 89; Aug 89; Dec 89; May 90; Aug 91; Feb 92; July 92; Sept 92; NovDec 92; & March 98 are sol d out. All other issues are currently i n stock. TOTAL $A B INDERS Pl ease send me _______ SILICON CHIP bi nder(s) at $A12.95 + $5.00 p&p each (Australi a only). N ot avail abl e elsewhere. Buy five and get them postage free. $A SUBSCRIPTIONS ❏ New subscription – month to start­­___________________________ ❏ Renewal – Sub. No._______________   ❏ Gift subscription ☞ RATES (please tick one) Australia Australia with binder(s)* NZ & PNG (airmail) Overseas surface mail 2 years (24 issues) 1 year (12 issues) ❏ $A90 ❏ $A49 ❏ $A114 ❏ $A61 ❏ $A135 ❏ $A72 ❏ $A135 ❏ $A72 ❏ $A240 Overseas airmail ❏ $A120 *1 binder with 1-year subscription; 2 binders with 2-year subscription GIFT SUBSCRIPTION DETAILS Month to start__________________ Message_____________________ _____________________________ _____________________________ Gift for: Name_________________________ (PLEASE PRINT) YOUR DETAILS Your Name_________________________________________________ (PLEASE PRINT) Address___________________________________________________ Address______________________ _____________________________ State__________Postcode_______ ______________________________________Postcode___________ Daytime Phone No.____________________Total Price $A __________ ❏ Cheque/Money Order ❏ Bankcard ❏ Visa Card ❏ Master Card 9am-5pm Mon-Fri. Please have your credit card details ready ______________________________ Card expiry date________/________ Card No. Phone (02) 9979 5644 Signature OR Fax (02) 9979 6503 Fax the coupon with your credit card details 24 hours 7 days a week Mail coupon to: OR Reply Paid 25 Silicon Chip Publications PO Box 139, Collaroy 2097 No postage stamp required in Australia October 1995  31 PART 2: Last month, we presented the circuit details of our new Railpower Mk.II controller. We follow up this month with the construction details and a testing procedure for the completed unit. It can be run from a standard 12V battery charger or a model railway power supply. By RICK WALTERS L ET’S STATE AT THE OUTSET that the Railpower Mk.II is a highly flexible design and there is no reason why it has to be built up in the way we are presenting it in this article. We are featuring it in two plastic cases, one for the pushbutton control unit and a large case for the microprocessor-controlled pulse pow- 32  Silicon Chip er board. Many people will probably want to build the main board into a large console while others will want to conceal it underneath their layout. So be it. You can do it in several ways. Just remember that the basic circuit, as featured on the two PC boards, cannot be varied unless you really know what you are doing. Neither can you change any of the basic performance or operational features of the circuit, since virtually everything is under the control of the microprocessor; its Railp A Wa F internal program­ ming is fixed and immutable. With that proviso, let us now de­scribe the construction of our prototype. The main pulse power board is housed in a standard plastic instrument case measuring 204mm wide, 67mm high and 156mm deep. The front panel features the six board-mounted LEDs and the 8-pin DIN socket. The rear panel is bare except for a 5-way insulat­ed terminal block which carries the power input and track output wires. The hand control uses a small plastic case measuring 60mm wide, 30mm thick and 120mm deep. It connects to the main unit via a cable fitted with an 8-pin DIN plug. Before you begin assembly, both PC boards should be closely inspected for etching faults. Any broken tracks power MkII: alk -Around Throttle For Model Rail­ways should be re­ paired and any shorts cleared with a sharp knife. In particular, look closely at the two thin tracks between the pads of IC1 on the main PC board. and diodes. Next, fit the low profile capacitors and preset potentiometers. The four ICs are all ori­ented in the same direction, with the notched end facing the DIN socket end of the board. It is a good idea to solder the supply pins of each IC first, and then all the other pins. For IC1, the supply pins are 5 & 14, for IC2 & IC4, the supply connections are pins 16 & 8 while for IC3 they are pins 14 & 7. Main board assembly It is probably better to assemble the main board first. Its component overlay is shown in Fig.1. Fit and solder the five links, then the resistors Q11 TRACK 10uF 1k 10k BUZZER 10k 560  REG1 1.8k 2.2k D1 470  Q9 10k LED2 IC4 74HC42 LED4 IC3 74HC11 1 680  470  LED3 0.1 .047 10k 10uF 1 VR1 VR2 VR3 Q3 22k 10k D4-D7 VR4 470  ZD1 2x 22pF D2 4.7k 10k 1 180k 0.1 VR5 AC INPUT IC2 74HC051 X1 10k 10k 1 Q4 1k D3 IC1 Z86E08 Q8 10k 2200uF DIN SOCKET Q2 Q1 0.1  5W 10k LED1 Q6 Q5 Q7 LED6 LED5 TRACK 10k Q12 22k Fig.1: the component overlay for the main PC board. Note the heatsink assemblies for Q2 & Q6 and for Q4 & Q8. These have been drawn so as not to obscure the surrounding resistors although, in practice, they are mounted above these components. 22uF 0.1 10k Next, install the small signal transistors which are all BC338s except for Q12 which is a BC328. Then fit the larger components, ensuring that the electrolytic capacitors and the buzzer, are inserted with the correct polarity, as shown on the wiring diagram of Fig.1. The four power transistors are mounted in back-to-back pairs, Q2 with Q6 and Q4 with Q8. This physically 22k GND Q10 2200uF 0.1 October 1995  33 A bird’s eye view of the main PC board in the case. Note how the heatsink assemblies for the power transistors face outwards from each other. Don’t get the transistors mixed up when you’re mount­ing them otherwise they’ll emit smoke when you turn on the power. connects their collector tabs together with the heatsinks sandwiched between the metal tabs of the transistors. There is no need to use mica washers for the heatsinks but the metal collec- tor tabs should have a light smear of heatsink compound before they are assembled and bolted together. In practice, we suggest you bolt the tran­ sistor pairs together with their Q8 BD649 HEATSINK HEATSINK Q4 BD650 Q6 BD649 Q2 BD650 Fig.2: this diagram shows how the four power transistors are mounted in back-to-back pairs, Q2 with Q6 and Q4 with Q8. This physically con­nects their collector tabs together with the heatsinks sandwiched between the metal tabs of the transistors. There is no need to use mica washers for the heatsinks but the metal collector tabs should have a light smear of heatsink compound before they are assembled and bolted together. 34  Silicon Chip heatsinks and then insert and solder the transistor pairs to the PC board – see Fig.2. Take particular care to make sure that you pair up the right transistor types and don’t swap their connections around when mounting them on the PC board otherwise they will blow as soon as you apply power. The LEDs should be tested before the leads are bent, as it appears that there are non-standard ones around. Normally, the longer lead is the anode, which should go to the more positive side of the circuit. To test the LEDs use a 6V or 9V battery and the 560Ω resis­tor used in the hand control. Connect the resistor to the battery positive and the longer lead of the LED to the free end of the resistor. The other LED lead goes to the battery negative. If the LED lights it is a standard type; if it doesn’t, reverse the LED leads. If it now lights, cut a couple of VR1 MOUNTED ON COPPER SIDE METER 10k VR1 S1 2 2 4 1 S2 D4 6 D2 8 5 3 7 D3 LED3 8-PIN DIN PLUG SOLDER SIDE LED2 D5 D1 S3 Fig.5: this diagram shows the pin numbers of the DIN plug, look­ing at the solder side. Solder pin 8 first. S4 LED1 1 IC1 74HC42 LED4 560  S5 4.7k S6 4.7k 0.1 6 D6 4 7 3 5 TO DIN PLUG 10uF 8 1 Fig.3 (left): this is the component overlay for the hand control board. Trimpot VR1 is mounted on the copper side of the board, as indicated by its dotted outline. Note the orientation of each pushbutton switch. Seven of the DIN cable connections are shown at the bottom of the diagram while the eighth, marked “2” is at the top righthand corner. Fig.4 at right shows the full-size PC etching pattern. millimetres off the end of the longer lead, making it the shorter one. This way, all the LEDs will be similar when you come to bend them. If a LED still doesn’t light, it is faulty and should be discarded. While you have this test setup you should check the LEDs to be used in the hand control, but don’t bend their leads, as they stay straight. Looking at the LED leads with the longer one on the right, bend them both down, 8mm out from the LED body. The six LEDs on the main PC board should all have their leads bent this way. Front panel Before you solder the LEDs into the board, you need to check their alignment. Carefully affix the Dynamark label to the front plastic panel and drill out the six 5mm LED holes and the DIN connector hole. Insert LED6 (red) and LED5 (green) into the PC board and solder one leg of each, leaving about 8mm of lead above the top of the board. Insert the LEDs This photo gives a close-up view of the output transistor pairs. The collector tabs should have a light smear of heatsink compound before they are bolted to the heatsinks. through the front panel and slide the assembly into the guides at each end of the case. Screw the PC board into the bottom of the case using 6mm spacers to lift the board off the plastic pillars. Check the alignment of the LEDs through the front panel holes. If all is OK, unscrew the PC board, fit the other LEDs with similar spacing and solder all the leads. If you are not happy with the LED alignment make any neces­ sary adjustments. This completes the assembly of the main board. It cannot be tested without the hand control, so let’s build that next. The component overlay diagram for its PC board is shown in Fig.3. Hand control board After building the main board you will find this one much quicker and easier. Look carefully at the overlay and place the components as shown. Fit and solder the IC, resistors and diodes, making sure the resistors are bent over parallel to the board, or else they will be damaged when you mount the board in the case (see photo). Next fit the capacitors and push buttons making sure the flat side of each button faces the centre of the PC board. Run an insulated wire on the copper side of the board, from the pad adjacent to the 10kΩ resistor, to pin 16 on IC1. The preset potentiometer should be soldered last, as it is mount­ed on the copper side, so that you can adjust it without unscrewing the PC board. If you wish, you could drill a hole in the back of the plastic case, allowing you to make adjustments to this preset without removing the back. The LEDs can be soldered in now, although it’s best to leave them until the PC board is assembled into the October 1995  35 When you have finished assembling the hand control board the two 4.7kΩ resistors and the 10µF capacitor near the cable end must be laid flat, in order to fit into the case. This is the copper side of the board, after the cable has been terminated. Note the trimpot (VR1) at the top if the board. Leave slack on the cable leads, to avoid any stress. Some of the IC pins are unsoldered; there is no point in soldering unused pins. The completed hand control board is secured to the top half of the case which must be drilled to accept the meter, the pushbutton switches and the LED indicators. Note that the tops of the LEDs should just protrude through the case. plastic case. They can then be pushed right into the hole in the case front and their leads soldered. Now that both boards are finished, you can assemble the hand control. Hand control case The meter is mounted on the front of the plastic case (the half with the threaded brass inserts), at the end with the mould­ed recess on the front. Turn the case over and drill out the two plastic pillars. Start with a drill just big enough to remove the brass thread, then fit a drill two sizes larger and drill out again, repeating until the pillars are removed. Place the front panel template 36  Silicon Chip (Fig.7) on this half of the hand control and mark all the holes. Drill out the pushbutton and LED holes. Make the cutout for the meter either by drilling a series of holes, then cutting and filing the plastic or by using a small coping saw. Finally, drill the two mounting holes for the meter. Drill a 12mm hole centrally in one of the dark grey end pieces. Remove 100mm of insulation and screen from one end of the 9-way cable and clamp it in the end piece, using the cable clamp, leaving 5mm of the outer covering protruding through. Mount the control board in the case using the two 10mm metal thread screws and 5mm spacers to hold it in position. Check each button operation, making sure each operates without jamming. If a button is not free to move, slacken the mounting screws and readjust the board position, or ream out the offending hole. When all buttons are operating properly, mark the position of the top mounting hole for the PC board, through onto the front panel. Remove the PC board, drill the hole and countersink it in the front of the case to allow the 2.5mm machine screw to sit flush. Hold the board so that, when you look at the components, the red button is at the bottom right. Insert both the righthand LEDs into the PC board with the long lead on the righthand side. The lefthand LEDs should have their long lead on the lefthand side. The red LED goes above the STOP button, the green above the FORWARD button, The yellow above REVERSE and the orange above INERTIA. Replace the control board using the 12mm countersunk screw, 8mm spacer and nut, as well as the metal Design Philosophy For the Railpower Mk.II While last month’s article gave a comprehensive circuit de­ scription, we did not have the space to fully describe some of the operating features, especially as they related to our very popular Railpower design featured in April & May 1988. While that design was very effective, there were a number of features which we would have liked to improve upon but could not, without an excessive amount of extra circuitry. In particular, we have had comments from readers about the following points. When the Railpower was turned off, it inevitably caused any loco on the track to give a very slight lurch forward. At about the same time, the overload protection buzzer would briefly sound at a low level. This happens because the op amps in the circuit lose control once the supply voltage drops to a very low value. It’s a minor problem but a problem that would be nice to solve. While some examples of the Rail­ power with infrared remote control came on with Forward selected, most seemed to come on with Reverse selected and while this was easily corrected by pushing the Forward button before pushing the Faster button, again it was something we would have liked to fix. A more subtle problem involved the minimum speed setting. In order to make the controls more respon- thread screws and spac­ers, checking the operation of all the buttons again. Once all is OK, push the LEDs forward until they protrude satisfactorily through the front panel then solder all leads of the LEDs. Cable termination Slide the grey endpiece with the cable into the channels, at the end away from the meter, then cut and solder the wires as detailed in Table 1, leaving around 20mm of slack on each one. The terminations for the wires are marked on the copper side of the board. Pins 1-8, excepting pin 2, are all at one end of the board. Pin 2 is at the other end of the board. To make it easier to follow, we sug- sive, we provided a minimum speed trimpot and this was set to provide a low voltage across the track so that the locomotive was just on the point of moving. However, with many locomotives, the very narrow pulse output at the minimum speed setting caused an audible buzz. There was no way around this. In designing the microprocessor version of the Railpower, we were able to address all the above problems without any added circuitry – it was all done in the programming. Hence, when power is first applied, the Railpower controller always comes on with STOP selected. To make the loco go forward, just press FOWARD and the FASTER button until the desired speed setting is ob­ tained on the meter. The minimum speed buzz problem was solved in the following way. If the train is stationary and Forward or Reverse is select­ed, then the minimum speed voltage will be applied to the track and the loco will produce a background buzz. However, if the train is stationary and the Stop button is pressed, the track voltage is reduced to zero; the loco will then be totally quiet. Forward/Reverse protection In the infrared remote control version of the Railpower (presented in April and May 1992), we added pro- gest that, as far as possible, you use the wire colours corresponding to the resistor colour code. The braid (shield) of the cable should also be connected to the PC TABLE 1 Colour Pin no. Pink 1 Red 2 Orange 3 Yellow 4 Green 5 Blue 6 Violet 7 Grey 8 tection against throwing the train into reverse while it was going forward at speed. Normally, if you throw a model train into reverse it is highly likely it will be derailed and that could cause lots of damage to expensive models (if the loco and wagons fall off the layout onto the floor). In the remote control version of the Railpower, the for­ ward/reverse protection prevented reverse from being selected until the train had been brought down to a very low speed. In the new microprocessor version we have taken a different approach. Now if you press Reverse while the train is going forward, it will come to a stop and then the controller will switch to Re­verse. However, it will not move off until you use the Faster button. That way, the modeller will get a positive response when the Reverse button is pushed, even if that outcome had not really been intended. The train is still protected against damage though. We have taken this alternative approach because some users find it confusing when there is no response to persistent pressing of the buttons. This way, you learn to press the right buttons. Finally, because the microprocessor allows nothing to happen unless a button is pressed, there is no disconcerting lurch from a locomotive when the unit is switched off and nor does the buzzer sound briefly. board. Cover the braid with a piece of sleeving and con­nect it to the pad marked B(raid). The cable we used had two green wires so we used the dark green for the termination; the light green wire should be cut off as short as possible, as it is not used. October 1995  37 Fig.6: this is the full-size etching pattern for the main PC board. Check your board carefully for etching defects before installing any of the parts. The Dynamark label can now be affixed to the front panel and the meter mounted. Run two wires from the PC pads marked “meter” to the meter terminals, left pad to left lug, right pad to right lug. The other end of the cable can now be terminated into the 8-way DIN plug. To prevent the pins moving as you solder them, push the plug into the socket on the main board. Don’t forget to slide the outer rubber sleeve of the plug, small end first, onto the cable before you begin! Cut the insulation and sheath back about 30mm, cut off the light green wire, and using the previous table connect the wire colour to the corresponding pin number. We have shown the pin markings for an 8-pin DIN socket in the diagram of Fig.5 as some DIN sockets do not have the pin markings and even if they do, they can be hard to see even under good lighting. The braid should be threaded through the hole in one of the clamps that restrain the cable, then soldered. Check the colours against the numbers again, then reassemble the plug. Testing Set trimpots VR1 (Inertia) and VR2 (Brake) to mid position. Turn 38  Silicon Chip C C A A D B B A A B B A A HOLES: A = 9mm B = 3.2mm C = 2mm D = 2.5mm Fig.7: photocopy this diagram and use it as a template when drilling and cutting the holes on the hand control. the minimum speed control VR4 to minimum and the maximum speed control VR3 to maximum. Set the Meter adjustment VR5 to centre position. Set trimpot VR1, in the hand control, anticlockwise. Power input to the main board can be from a standard 12V battery charger or from a 12-15VAC model railway power supply. Either way, you connect to the two PC pins on the board marked “AC input”. Plug the hand control into the main board and turn on the power. The green power LED on the main board should light imme­ diately, followed by the red Stop LEDs on main board and the hand control. Pressing the Forward button should extinguish the Stop LED and light the green Forward LED on both units. Pressing Reverse should cause the green LED to go out, the Stop LED to light briefly, then the yellow Reverse LEDs to light. Hold down the Faster button and the meter should start creeping up the scale. Release the button and the meter should instantly drop back then begin to climb slowly. Press Slower and the meter should jump upscale then creep back as the button is held down. If everything is working so far, it STOP RAILPOWER Fig.9: the full-size artwork for the hand control label. is time to test the unit in situ. Turn off the mains power and disconnect the wires from the main board and then mount it in the case. Fit a 5-way insulated terminal block to the back panel, as shown in the photograph, to take the wires for the AC input and track output. Connect the Railpower to your layout and place a loco on it. Turn on the mains power and the green power LED should come on as before. Pick up the hand control and press FORWARD, then hold FASTER down and if the train moves forward, the polarity of the wires to the track is correct. Note that the train may not move immediately, as the minimum speed preset was set to 0V. If the train runs backwards, swap the wires connecting the controller to the track. Calibration It will take a few attempts to get the adjustment of the trimpots to your satisfaction. The minimum and maximum speed trimpots will undoubtedly need resetting several times, as well as those for inertia and brake. As we explained in the circuit description last month, the microprocessor normally only reads the values set on the trimpots when the power is first turned on. To save you from having to turn the power off and on after each adjustment, it is only necessary to hold down the FORWARD button and then press and release the INERTIA button. Fault finding There are two rules to follow if it doesn’t go when you turn it on. The first rule is don’t panic and the second is don’t assume that you have a faulty IC or crook transistor. While it may be a shock to your ego, the most likely reasons why the unit does not work are shorts due to solder splashes on the underside of the board, poorly soldered or unsoldered connec­tions, crossed wires in the DIN connector cable or components in the wrong way. So the first step in rectifying any problem is to very thoroughly inspect your work. As all the LEDs have been tested, there shouldn’t be any problems associated with them. If you wish to check the DIN cable, use a multimeter set to a low Ohms range and check for continuity between each pin and its respective pad on the hand control PC board. If the green POWER LED does not light you may have a prob­lem with your power wiring or a short on the +5V line. You should have +5V at the output of REG1, at pin 5 of IC1, pin 16 of IC2 & IC4, pin 14 of IC3 & IC1 in the hand control and at Q12’s emitter. If the green LED lights but the red Stop LED does not light at power-on, the first step is to unplug the hand RAILPOWER INERTIA OV E FORWARD R L OA D REVERSE ST OP FO R W AR D RE V E IN RS ER E T I A OF F FASTER ER SLOWER This tells the microprocessor to read the trimpot values again. So each time you want to readjust the trimpots, press these buttons to get the new values loaded into the microprocessor’s memory. If you readjust the minimum speed it will be necessary to stop the train to make this new value effective. Once you are satisfied with the trimpot settings, you can calibrate the meter. Slow the train with the SLOWER button until it comes to a complete stop. Adjust trimpot VR1, in the hand control, until the meter’s pointer is on zero. Press FORWARD, wait until the green LED lights, then press INERTIA and the orange LED will light. Take the train to maximum speed, then set trimpot VR5 on the main board for a reading of 10 on the meter. There is a small amount of interaction between these two adjust­ments and it may take several attempts to get them spot-on. Note that if you change the settings of the maximum or minimum speed trimpots, you will have to recalibrate the meter. PO W SPEED Fig.8: the artwork for the front panel label of the main board case. control. Turn the power off, wait for 10 seconds then re-apply power. If it now lights, the problem is most likely in the cable connections. If all the LEDs light in the way they should when the but­tons are pressed, but the loco does not go, then the microproces­ sor is working and the fault is in the area associated with IC3 SC or the transistor H-bridge. October 1995  39 SERVICEMAN'S LOG The view was fabulous, but ... Yes, there’s usually a “but”, involving some kind of a trade-off for what looks like a perfect situation. In this case, a location with a fabulous view exacted its own price in terms of appliance reliability. It really was a beautiful view. This lady customer lives right on a beach front and one would have thought that, with paradise right on her doorstep, she would hardly need a TV set. In fact, she owned a very large double-ended lowboy with an AWA-Mitsubishi SC6341 AS630 chassis. It was the size of the set that necessitated the house call. And I was going to have to fix it in situ, because I could­n’t move it unaided. The problem was loss of vertical scan, there being just a horizontal line across the screen. I should have realised from the state of the cabinet veneer that the environment may have been to blame. When I removed the back, the cause was obvious – salt air corrosion. All the tinplate areas were rusty and the aluminium was pitted. Also, the horizontal output transformer didn’t look long for this world, with a telltale carbon track on the plas­tic. But worse still was the state of a lot of the small com­ponents, many of which were green from copper oxide Fig.1: the relevant section from the AWA-Mitsubishi SC6341 colour TV set. The vertical oscillator section of IC201 is shown at top and this drives the vertical output transistors (Q451 and Q452) at the bottom. The height control, VR452, is to the left of Q452. 40  Silicon Chip corrosion. Altogether, the long-term reliability of the set looked very poor and I informed the lady of this prognosis. She asked me to see what I could do. This chassis is the stereo version of the ML series and most of the deflection circuits are the same. The vertical time­base is fairly simple in terms of component numbers – a 48-pin IC (IC201) carries the vertical oscillator and drives the two output transistors (Q451/Q452). The correct value of 11.4V was applied to pin 33 of the IC but the collector of Q451 had 113V on it, in­stead of around 65V, suggesting the transistors were switched off and not being driven. Sometimes these circuits can be difficult to service, as it is often a chicken and egg situation, where a fault in any sec­ t ion, including the feedback path, can stop it from working. In this situation, it is hard to know where to start, especially as I didn’t have the CRO to turn to. But as luck would have it, the problem was fairly obvious from the state of the height control (VR452) which was badly corroded. I tried to adjust it while watching the screen. Impossible – the cabinet was too large; I had to ask the lady for some help. She was able to tell me that the horizontal line had expanded and was trying to fill the screen as I adjusted the control; that is, until the control disintegrated. I replaced it and the picture was restored. I then refitted the back and was going through a final check when I noticed that the stereo lights were not on and the sound was in mono. This was all I needed to remove the back again. This set uses the TDA3800G decoder and that was my initial suspect. However, I had blamed this unit unfairly on a previous occasion, so I looked around for another possible cause. The preset pots VR301, VR302 and VR303 caught my eye; they all looked bad. But replacing them presented a problem because I didn’t have any alignment equipment with me. I took a punt and used an in­delible felt tip marker to mark the positions of the wiper arms and then replaced all three controls. Fortunately, only VR302 and VR303 were the culprits and, by setting the wipers at the same angle as the originals, full stereo sound was restored and the LEDs were alight. I finally emptied half a can of CRC 2-26 all over the corroded areas and the horizontal output transformer, then I wiped and cleaned off the excess and dirt with a cloth. After replacing the back I had a word with the lady on how best to protect the set, at least for a while. I suggested she move it away from the open window overlooking the sea and place it as far as possible on the other side of the room, or even in another room on the other side of the house. Also, I recommended that she cover the set with a sheet, blan­ket, or even a plastic tarp when she wasn’t watching it, espe­cially during any humid weather or when onshore winds prevailed. She compromised by covering it with a table cloth away from the window and as far as I know it is still working, six months later. But, as I said earlier, there was a price to pay for that fabulous view. The red face My next story involves a video recorder that bounced. Any­thing that bounces has the makings of a red face situation and this was no exception. But there is a twist to the story. It started when a new lady customer brought a Philips VR6448/75 video recorder into the shop and complained that it chewed the tape on ejecting – sometimes. She added that she used the machine a lot and would appreciate it if I could fix it as soon as possible. It so happened I wasn’t particularly busy that day, so I tackled it almost immediately. The intermittent aspect didn’t help. It took about 10 tries to create the fault, whereupon it became fairly obvious; the tape wasn’t being fully wound back into the cassette prior to unloading, leaving a length of tape outside to be chewed up by the ejecting action. This turned out to be a partial failure of the reel idler assembly. I removed this, cleaned and tested it, replaced it, and tested it again. I then checked the idler shaft and found it to be sticking. It didn’t respond to normal treatment and so I decided to fit a new idler assembly and a set of belts and tyres. This machine is made by Sharp and so I rang the lady and quoted her on the basis of Sharp replacement parts. This worked out at $135.00 – $52.50 for the parts and $82.50 for labour. She accepted quite happily and I told her it would be ready that afternoon. I fitted everything back in, cleaned the heads and the machine generally, tested it, and was quite confident that it was in perfect condi­tion. The lady collected the machine later October 1995  41 in the day, paid by cheque, and thank­ ed me for being so prompt; another satis­fied customer, or so I thought. A real blast About three weeks later, I answered the phone one morning and a bloke identified himself as being from one of the local TV stations. And without waiting for any acknowledgement, he let fly with “what sort of guarantee do you give?”. Then, again without waiting for an answer, he went into a long diatribe about how I had ripped him off and that I didn’t know what I was doing. What’s more, he demanded that I should immediately call at his place and fix his recorder properly. And he added that the tech­nicians at his station could have fixed the recorder properly at half the outrageous price I had charged (I wondered why he hadn’t used them). I’m afraid the strength of his blast caught me off guard and, initially, I couldn’t get a word in edgeways to even identi­fy the recorder. I did eventually and, of course, it was the lady’s husband, But even then, it was an effort to find out what the problem was. All he would say was, “It’s doing the same thing – it won’t eject” (which wasn’t the same thing). When he finally paused for breath I told him that my war­ranty was 90 days for the parts I had used and for my work; nothing else. I invited him to bring the recorder back in and I would look at it immediately. That wasn’t good enough – I had to drive out and fix it. I baulked at that and repeated my offer to check the ma­chine but only in my workshop. “Right”, he said, “I’m going to go through you like a packet of salts”. And he hung up. The “packet of salts” took the form of a call, shortly afterwards, from Consumer Affairs, acting on a complaint from him that I wasn’t prepared to fix his recorder. The C.A. man was strictly neutral and listened politely while I gave my side of the story and explained that I would attend to the matter as soon as the recorder was brought back. He said he would relay that to the complainant. Another week went by, a somewhat worrying period. No-one likes a repair to bounce, for whatever reason. While I was sure I had done a thorough job, there is always the risk of something being overlooked. But, try as I might, I couldn’t think what. Then he appeared, carrying the recorder. He was a lot quieter now – doubtless on the advice of the C.A. man – and was even polite, in a very reserved manner. I tried to be equally polite. He offered to leave the recorder with me and call back later. But I insisted that he wait while I examined the machine in front of him, to which he reluctantly agreed. I plugged the recorder in and confirmed the nature of the fault; a cassette was stuck inside and wouldn’t eject. I could hear the motors trying to turn but without result. It was clearly not the original fault. I removed the covers while he watched and began to turn the eject shaft gently by hand. And as the cassette lifted clear of the deck floor I experienced a wave of relief as I saw the cause of the problem. And it was simple enough for even the customer to see and understand – a ballpoint pen jammed underneath it. Talk about a red face – his reserve collapsed totally. To give him his due, he did apologise and said he would contact Consumer Affairs and put that right. But he didn’t offer to pay for having it fixed again. I had to realign the ejector assembly with the loading motor mode select switch, to restore the correct sequence. And I tested it to his satisfaction while he waited. Technically, I could have charged him again. But I wasn’t going to push it – honour was satisfied. J. L.’s video camera And now, on a completely different theme, I have a quite unusual story from my southern colleague, J. L. of 42  Silicon Chip Tasmania. Here’s how he tells it. I’ve had a very interesting job over the last few days. It was the sort of job that usually goes only to specialist techni­cians, so I’ll tell it here as a word of warning to others who might get involved and as a gesture of thanks to the highly skilled technicians who helped me out of my trouble. It concerned my own video camera, a Panasonic model NV-MS4A. It’s a full-size Super VHS camera, a big, heavy thing that produces superb pictures. Or at least, it did until my son gave it a hefty thump while out filming one day. As far as he can recall the camera was in its fitted case when the thump occurred and there is no sign of damage on either the case or the camera. But in fact, the camera had suffered internally and would not work next time he tried to shoot. The deck would not load or unload a tape but had stopped half way through one or the other process. However, it did eject the tape and a mangled S-VHS cassette was the result. Next day, I took it to the local Panasonic specialists for repair. I was over optimistic because, as it turned out, they had three weeks work on hand and could not help me for at least that long. And I needed it before that. “Why not do it yourself?” they asked. “You’ve done plenty of VCRs and this is only a more com­pact version of the same thing!” Well, I had a manual for the camera and they offered to make available some vacant bench space and promised moral sup­port, so I set to work. First, I removed all the screws as per the manual. There were about 17 of them altogether and I expected the camera covers to more or less fall off. Alas for my high hopes! I pulled and tugged and pushed and prodded for 20 minutes but couldn’t get the thing apart. I worked so hard that I feared I might break the plastic panels but nothing I could do would expose the inside of the camera. Then their senior camera technician came over and said, “Here! What are you doing? You’ll smash the thing, handling it like that!” And with that, he poked a small screwdriver in through a couple of holes in the cover and both sides simply fell off! It seems that Panasonic designed this camera to a “belts and braces” standard. Not only are the covers held on with lots of screws, they are also held in place with plastic clips moulded into the inside of each half shell. Provision is made for pushing the clips out of the way to release the shells but no mention is made of this in the manual. You have to find out for yourself, or be shown, where these clips are before you can open the camera. One could smash the thing to pieces trying to get it open but once the secret is known, disassembly is quick and almost painless. Now that the mechanism was exposed, it was easy to see what had happened. A pin on a lever, intended to ride in a groove on the master cam, had jumped out and was sitting jammed on the top surface of the cam. It was easy enough to slip the pin back into the groove but this left the mode switch and mechanical timing way out of place. I struggled with gears and levers, trying to get everything back into position but I was getting nowhere. The mechanical instructions in the manual I was working from were written in excruciating Japanese English, so I had to ask for help from one of the other technicians. He is a better interpreter than I (or else, he has been through all this before) and he soon had every­thing back into place and the mechanism working properly. I reassembled the camera, refitted the covers and tested the unit to my satisfaction. It was the first time I had ever been inside a camcorder and I came away thinking that it was not a place in which I would like to spend too much time. Apart from anything else, my fingers are too thick and too insensitive to handle the tiny parts. K ALEX The UV People ETCH TANKS ● Bubble Etch ● Circulating LIGHT BOXES ● Portuvee 4 ● Portuvee 6 ● Dual Level TRIMMER ● Ideal PCB DRILL ● Toyo HiSpeed MATERIALS ● PC Board: Riston, Dynachem ● 3M Label/Panel Stock ● Dynamark: Metal, Plastic ✸ AUSTRALIA’S NO.1 STOCKIST ✸ K ALEX 40 Wallis Ave, East Ivanhoe 3079. Phone (03) 9497 3422, Fax (03) 9499 2381 TRANSFORMERS • TOROIDAL • CONVENTIONAL • POWER • OUTPUT • CURRENT • INVERTER • PLUGPACKS • CHOKES It’s not fixed yet Now, if you think that this is the end of the story, you’re wrong. It’s only just begun. I used the camera that weekend and shot some perfect foot­age. Then my son took the camera on the Monday and that evening complained that it would not record in colour and had a red line down the righthand side of the picture. He felt it might be a physical problem since the camera seemed to work reasonably well when hand-held but played up when mounted on the tripod. We soon found that we could make the fault come and go by pressing STOCK RANGE TOROIDALS BEST PRICES APPROVED TO AS 3108-1990 SPECIALS DESIGNED & MADE 15VA to 7.5kVA Tortech Pty Ltd 24/31 Wentworth St, Greenacre 2190 Phone (02) 642 6003 Fax (02) 642 6127 October 1995  43 that suggested to him that this was a delay line fault. As it turned out, he wasn’t wrong. I had quite a difficult job finding the delay line. In fact, there are two in the camera, one a 1H line and the other a 2H. Neither looks anything like a conventional TV delay line. The 1H line is in an 8-pin IC package, similar to but smaller than a 555 timer chip. The 2H delay line looks like another IC but is in a 16-pin package. Once I had identified the delay lines, I was able to exam­ine them for signs of dry joints. This was rather inconclusive since, under a strong glass, the solder looked rather crystalline but no more so than hundreds of other joints on the board. Still, I had been assured that at least one of the 24 pins on these two chips had to be loose, so I fitted the finest point into my soldering iron and gave each one a touch of heat. And that was all it took. The fault disappeared and has not returned. I haven’t been able to learn if my friend solved the prob­lem using experience or theory. Chroma delay line problems are so rare that I have never had one in all my years of servicing colour TV sets or video recorders. They are not unknown, of course, but are so unusual that few people build up a fund of experience. lightly on the side of the camera body, in the vicinity of the main PCB. It was as well that I’d learned the secret of the plastic clips because I was going to have the covers on and off many times over the next few days. With the main PCB exposed, I found that the fault did indeed respond to gentle pressure but only on one end of the board. It was obviously a dry joint but on a 100 x 150mm double sided board, thickly coated with micro-miniature surface mount components, I didn’t like my chances of finding it. The fact that the fault seemed only to affect the chroma circuits helped to reduce the area of confusion but, even so, it involved hundreds of tiny components on both sides of the board. I used a fine dental pick to gently prod and poke all the components I could identify as part of the chroma circuitry. The PC patterns are given in the manual but only the larger and less crowded components are listed. Dozens of chip resistors and capacitors are simply not shown on the pattern, 44  Silicon Chip which makes iden­tifying the various parts rather difficult. Several times I poked at a component and the fault disap­peared. Whenever it stayed “disappeared”, I hoped that I might have cured the problem by accident and so reassembled the camera and gave it a test run. This went on half a dozen times before I realised that, by myself, I would never be able to solve the problem. In the absence of more precise information about the exact nature of the fault and therefore its physical location, I could hunt forever and never track it down. So it was back to my friends at the service centre. I played back some of the test tape I had been running and their senior technician said straight away “that’s a delay line fault!” When I demonstrated that it could be turned on and off by pressing on the board, he opined that it had to be a dry joint on one or another of the delay line pins. It seems that it was the red line down the righthand side of the screen Minor hassles The job wasn’t quite over since I had no end of trouble getting everything back into place. I misaligned a 30-pin plug and socket connector and had the whole machine reassembled before I found that the camera section wasn’t working. Then, when I fixed that, there was no servo control because a 30-pin flexible connector had slipped out of place. Then the zoom lens wouldn’t work, because I had somehow dislodged its tiny 3-pin plug in the process of replacing the side cover! It’s been an interesting experience but I have never been so pleased to complete a job. I would never have undertaken the task if the camera had not been wanted urgently. I think my friends at the service centre are entitled to every penny they make from camera repairs. Thanks, J. L., for a most interesting and unusual story. It just goes to show that you never know what you can do SC until you try. SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP BOOK SHOP Newnes Guide to Satellite TV 336 pages, in paperback at $49.95. Installation, Recept­ion & Repair. By Derek J. Stephen­son. First published 1991, reprinted 1994 (3rd edition). This is a practical guide on the installation and servicing of satellite television equipment. The coverage of the subject is extensive, without excessive theory or mathematics. 371 pages, in hard cover at $55.95. Servicing Personal Computers By Michael Tooley. First pub­ lished 1985. 4th edition 1994. Computers are prone to failure from a number of common causes & some that are not so common. This book sets out the principles & practice of computer servicing (including disc drives, printers & monitors), describes some of the latest software diagnostic routines & includes program listings. 387 pages in hard cover at $59.95. The Art of Linear Electronics By John Linsley Hood. Pub­lished 1993. This is a practical handbook from one of the world’s most prolific audio designers, with many of his designs having been published in English technical magazines over the years. A great many practical circuits are featured – a must for anyone inter­ested in audio design. Optoelectronics: An Introduction By J. C. A. Chaimowicz. First published 1989, reprinted 1992. This particular field is about to explode and it is most important for engineers and technicians to bring themselves up to date. The subject is comprehensively covered, starting with optics and then moving into all aspects of fibre optic communications. 361 pages, in paperback at $55.95. Digital Audio & Compact Disc Technology Produced by the Sony Service Centre (Europe). 3rd edition, published 1995. Prepared by Sony’s technical staff, this is the best book on compact disc technology that we have ever come across. It covers digital audio in depth, including PCM adapters, the Video8 PCM format and R-DAT. If you want to understand digital audio, you need this reference book. 305 pages, in paperback at $55.95. Power Electronics Handbook Components, Circuits & Applica­ tions, by F. F. Mazda. Published 1990. Previously a neglected field, power electronics has come into its own, particularly in the areas of traction and electric vehicles. F. F. Mazda is an acknowledged authority on the subject and he writes mainly on the many uses of thyristors & Triacs in single and three phase circuits. 417 pages, in soft cover at $59.95. Surface Mount Technology By Rudolph Strauss. First pub­ lish-ed 1994. This book will provide informative reading for anyone considering the assembly of PC boards with surface mounted devices. Includes chapters on wave soldering, reflow­ soldering, component placement, cleaning & quality control. 361 pages, in hard cover at $99.00. Electronics Engineer’s Reference Book Edited by F. F. Mazda. First pub­ lished 1989. 6th edition 1994. This just has to be the best reference book available for electronics engineers. Provides expert coverage of all aspects of electronics in five parts: techniques, physical phenomena, material & components, electronic design, and applications. The sixth edition has been expanded to include chapters on surface mount technology, hardware & software design, Your Name__________________________________________________ PLEASE PRINT Address____________________________________________________ _____________________________________Postcode_____________ Daytime Phone No.______________________Total Price $A _________ ❏ Cheque/Money Order ❏ Bankcard ❏ Visa Card ❏ MasterCard Card No. Signature_________________________ Card expiry date_____/______ Return to: Silicon Chip Publications, PO Box 139, Collaroy NSW, Australia 2097. Or call (02) 9979 5644 & quote your credit card details; or fax to (02) 9979 6503. semicustom electronics & data communications. 63 chapters, in paperback at $140.00. Radio Frequency Transistors Principles & Practical Appli­ cations. By Norm Dye & Helge Granberg. Published 1993. This timely book strips away the mysteries of RF circuit design. Written by two Motorola engineers, it looks at RF transistor fundamentals before moving on to specific design examples; eg, amplifiers, oscillators and pulsed power systems. Also included are chapters on filtering techniques, impedance matching & CAD. 235 pages, in hard cover at $85.00. Newnes Guide to TV & Video Technology By Eugene Trundle. First pub­ lish-ed 1988, reprinted 1990, 1992. Eugene Trundle has written for many years in Television magazine and his latest book is right up date on TV and video technology. 432 pages, in paperback, at $39.95.  Title Price  Newnes Guide to Satellite TV  Servicing Personal Computers  The Art Of Linear Electronics  Optoelectronics: An Introduction  Digital Audio & Compact Disc Technology  Power Electronics Handbook  Surface Mount Technology  Electronic Engineer's Reference Book  Radio Frequency Transistors  Newnes Guide to TV & Video Technology $55.95 $59.95 $49.95 $55.95 $55.95 $59.95 $99.00 $140.00 $85.00 $39.95 Postage: add $5.00 per book. Orders over $100 are post free within Australia. NZ & PNG add $10.00 per book, elsewhere add $15 per book. TOTAL $A October 1995  53 A fast charger for nicad batteries This nicad charger lets you fast charge nicad battery packs from a 12V car battery. It can charge packs of 5 to 10 cells at once and automatically reverts to trickle mode at the end of the charging cycle. By JOHN CLARKE Nicad battery packs seem to have a habit of going flat just when you want to use them, particularly when there is no readily available source of mains power to operate a recharger. Of course you can always call upon a spare battery but what happens when it also goes flat after some use? This Extra Fast Nicad Charger is the answer to your nicad battery problems. It operates from a car battery so you don’t need mains power and it can recharge a nicad battery pack in far less 54  Silicon Chip time than it takes using a conventional charger. At the maximum charge current of 4A, you can charge a 1.4Ah battery in less than 30 minutes. For higher capac­ity batteries, the charge time will be longer but most batteries with less than a 2Ah capacity can be charged in under 45 minutes. Sensing techniques With high charge rates, nicad batteries can be damaged if they are not charged correctly. As a result, the Extra Fast Nicad Charger employs four sensing methods to ensure that charging ceases before any damage is done to the cells. These are as follows: (1). Over-temperature sensing: If nicad cells are overcharged, they become hot and this causes cell damage. To prevent this from happening, the circuit monitors the temperature of the battery pack using a thermistor and switches the circuit to the trickle charge mode if the temperature rises above a preset level (45°C). (2). Low voltage sensing: Nicad cells that have been discharged to a very low voltage can be damaged if initially fast charged. The circuit prevents this by monitoring the battery voltage and initially trickle charging the battery until it reaches a preset value. It then automatically switches over to fast charging. (3). Voltage sensing: When a nicad VP 12 VS 6 Vref 10 Rn 11 IB 5 NTC 3 CP 9 Vr1 In SUPPLY GND 16 Vhigh PROTECTION Vr3 MAINS ON RESET V LSP Iref > t AO 2 A2 Vr2 Vlow PROTECTION Vr4 LS 4 A1 > > OSC DISABLE TIME OUT > R s+h BATTERY FULL DETECTION VAC 7 PWM 1 PWM & R TIME OUT PROTECT LED 15 > R 1/10 OSC TO PWM :1:2:4 PRESCALER COUNTER CONTROL CURRENTLESS SENSING AUX PULSES 13 OSC 8 PR 14 SYNC Fig.1: block diagram of the TEA1100 which is designed specifically for nicad battery charging. It includes automatic timeout and -dV detection circuitry and features both linear and PWM outputs. the LED flashes, the charger is in trickle charge mode. Battery charger IC battery pack is fully charged, further charging causes its output voltage to fall slightly. This slight voltage drop is sensed using a method known as -dV detec­tion, at which point the circuit is switched to the trickle charge rate. (4). Automatic timeout: As a final precaution, the circuit em­ ploys a timer which can be set to one of six intervals ranging from 30-180 minutes. If, for some reason, the battery voltage does not drop within a certain time, this timer automatically switches the circuit to trickle charge mode. Note that -dV detection can be unreliable if it takes longer than one hour to fully recharge a battery. This is because the output voltage drops very slowly after full charge at the lower charging currents and may not be detected. The timer is a “belts-’n-braces” feature – it’s there as a backup if the -dV sensing circuit fails to detect full charge. compact plastic case. There are just three switches on the front panel: (1) an on/off switch; (2) a 6-position rotary switch to set the timer (30-180 minutes); and (3) a 5-position rotary switch to set the charging current (1-4A). A table on the front panel shows the required switch set­tings for the various battery capacities available. These set­tings must be used in order to prevent battery damage. Also on the front panel is a LED indicator which shows the charging mode. When the LED is continuously lit, the charger is fast charging. When Main Features • • • Indicators & controls As shown in the photos, the Extra Fast Nicad Charger is housed in a The circuit is based on a Philips TEA1100 charger IC which is specifically designed for nicad cells. Its schematic is shown in Fig.1. Most of the IC circuitry is controlled by a single oscilla­tor which is used for timeout counting, driving a pulse width modulator (PWM) for switch mode operation, and for various timing processes. These timing processes include a periodic “quiet time”, during which battery charging ceases so that its voltage can be measured without switchmode noise. In the trickle charge mode, the PWM output is applied in short • Fast charging Powered from a car battery Charging stopped using three detection methods: by monitoring battery temperature, drop in battery voltage at full charge and charging time Five charging currents from 1-4A • Suits most battery packs with 5-10 cells • • • Charging indicator LED • Trickle charging after fast charge Fuse protection for reverse polarity and shorts Short-circuit proof October 1995  55 F1 10A S1 12V BATTERY 10  4700 50VW 4700 50VW 4700 50VW 0.47 +8V 4 1.8k 6 8 IC2 7555 2 6.8k 3 10  2.2k 0.1 C A Q3 BC328 D1 MBR735 K A 56k NICAD BATTERY N2 Q1 IRF540 D 0.1  5W 2.2k 3.9k 1 S2 : 1 : 4A 2 : 3.5A 3 : 2A 4 : 1.8A 5 : 1A 1k 3 2 CURRENT SET S2 2k 7 VAC 1.1k 4 5 IB K A EXTRA FAST NICAD CHARGER K MINUTES S3 : 1 : 180 2 : 120 3 : 90 4 : 60 5 : 45 6 : 30 .001 TIME SET S3b 2 1 3 4 5 6 56  Silicon Chip VS 6 NTC GND 3 16 TEMP SET VR1 500k * DSE R1797  100k 6 5 .033 10 47k .001 11 220k 9 56k 27k VREF 10 PR 8 1 TIME SET S3a 2 4 3 *OR 100k Fig.2: the circuit of the charger. IC2, Q2 & Q3 together drive Mosfet Q3 and this switches transformer T1 to form a boost converter. This steps up the 12V input voltage to a level sufficient to charge as many as 10 nicads in a battery pack; ie, a maximum of about 18V. The boost convert­er is under the control of IC1, the TEA1100 battery monitor. bursts for about one period on to 10 periods off. Apart from the oscillator, the IC circuitry is also con­trolled by a resistor which is connected between Vref (pin 10) and ground. This resistor sets up a current reference (Iref) for the circuit. The actual charge current is then set by this refer­ence current and the value of an external current set resistor. In operation, the IB pin monitors the voltage across an external dropping resistor which carries the nicad charge cur­rent. This voltage is then fed to internal op amp A1. Any error will be amplified by A1 and compared with the oscillator waveform in a PWM comparator. The result is a pulse train at pin 1 with a duty cycle varying according to the error signal at the A1 output. The CP input, pin 9, controls the RN CP .0015 A 15 LED 4 LS IC1 TEA1100 .01 B E C VIEWED FROM BELOW 12 V+ 5 1 PWM OSC 13 GD S 1 16VW 15k C 4.3k I GO  K 0.1  5W S E 10 16VW LED1 N1 E 10W G B 5 1 B GND 100 16VW OUT T1 0.1 Q2 BC338 ZD1 16V +12V 1W 0.47 +12V 0.1 IN REG1 7808 output polarity at pin 1. In addition, an analog output appears at pin 2 and is used to control circuits employing linear regulation. This latter output is not used in this design, which employs PWM control only. During trickle charge, a resistor at Rn (pin 11) controls the current into the battery. The current is also deter­ mined by the state of the PR pin (pin 8) which controls a pre­scaler to divide the oscillator signal by 1, 2 or 4. Pin 7, the VAC input, monitors the voltage of the battery being charged. For normal (ie, fast) operation, this voltage must be between 0.385V and 3.85V and is set using a voltage divider network to suit the batteries that are to be charged. A voltage on pin 7 that’s outside this range initiates the trickle charge mode. In addition, the battery full detection circuitry initiates the trickle charge mode when it detects a 1% fall in battery voltage. The NTC input at pin 3 is used to monitor the voltage across a thermistor. This is the temperature sensing circuit. As shown, it drives a couple of internal Schmitt trigger compara­tors. When the temperature of the battery pack exceeds a certain value (ie, when the voltage at pin 3 drops below a critical level), one of the Schmitt triggers toggles and the current is reduced to trickle mode (the other Schmitt trigger is used for under-temperature sensing but this is not a problem in Aus­tralia). Finally, the LED output at pin 15 goes low when the IC is in fast charge mode. Alternatively, this pin switches between high and low (to flash the LED) when the IC reverts to the trick­le charge mode. Circuit details Refer now to Fig.2 for the full circuit details. Apart from the TEA1100 This inside photo shows the general arrangement of the PC board in the case. Note how mica washers have been used to set the gap between the transformer cores (see text). IC, it employs a 7555 timer (IC2) two tran­sistors, an N-channel Mosfet and a 3-terminal regulator (REG1). The resistors at pins 10 & 11 of IC1 set the reference currents for the fast and trickle charge rates, as described previously. The oscillator control input is at pin 13 and this pin is connected to ground via one of two capacitors, as selected by S3b. When the .0015µF capacitor is selected, the oscillator runs at 25kHz. Conversely, when the .001µF capacitor is selected, the frequency increases to 37kHz. S3a selects the prescaler value. In positions 1 & 2, pin 8 is grounded and the prescaler divides the oscillator frequency by 4. Similarly, positions 3 & 4 set the prescaler to divide by 2 (pin 8 open circuit), while positions 5 & 6 set the prescaler to divide by 1 (pin 8 connected to the 4.2V bias voltage Vs at pin 6). Combined with switch S3b, S3a sets the timeout period to one of six values: 30, 45, 60, 90, 120 & 180 minutes. The NTC input (pin 3) is connected to a thermistor and also to the 4.2V bias voltage via VR1 and a 100kΩ resistor. Normally, the thermistor resistance is about 100kΩ at 25°C. However, as the temperature rises, the thermistor resistance falls and this reduces the voltage at the NTC input. If the voltage at the NTC input falls below 0.8V, the IC immediately switches to trickle mode and remains there until the voltage increases to about 0.9V. VR1 allows the temperature trip point to be adjusted, while the adjacent .033µF capacitor prev­ents false triggering by bypassing any high frequency signals from the switchmode supply. The PWM output at pin 1 of IC1 is designed to drive a step-up converter and this is based here on Mosfet Q1, transform­er T1 and Schottky diode D1. In practice, however, the PWM wave­ form at pin 1 is not suitable for directly driving the Mosfet. This is because the voltage does not swing sufficiently high to fully turn on the device, nor is the output current sufficient to charge the gate capacitance of the Mosfet in the time allowed. To overcome this problem, 7555 October 1995  57 Q1 BC328 10  0.47 NICAD+ GND T1 Q3 GND 0.1 D1 Q2 0.47 4700uF +12V 0.1  5W 4700uF 1 56k BC338 0.1  5W 15k .0015.001 0.1 0.1 56k 1k K LED1 A 220k 27k S3b 4700uF 1uF S3a 1,2 10uF REG1 4.3k S2 WIPER 5 4 3 S2 2 1 Fig.3: install the parts on the PC board as shown in this wiring diagram, taking care to ensure that all polarised parts are correctly oriented. Note that Q2 is a BC338 transistor while Q3 is a BC328 type, so don’t get them mixed up. timer IC2 is used as a buffer stage. This is a rather unusual application for a 7555 timer IC, since it does not function as a timer at all. Instead, it is used to convert the 0-7V PWM signal to a 0-12V signal at its pin 3 output. As shown on Fig.2, the upper threshold of the 7555 is set to about 2V by the 6.8kΩ and 2.2kΩ resistors at pin 5. This, in turn, sets the pin 2 threshold to 1V. As a result, when pins 6 & 2 are taken above 2V, pin 3 goes low. Conversely, when the input goes below about 1V, pin 3 goes high. Because IC2 is powered from +12V, it effectively converts the PWM output from IC1 into a 0-12V signal. It also inverts the signal and so to maintain the correct output phase, the PWM output from IC1 is inverted by connecting a 56kΩ resistor to the CP input at pin 9. 58  Silicon Chip 10  3.9k .001 S3a 5,6 2.2k 47k .01 VR1 1 2k 100k 1.1k 1 IC2 7555 ZD1 2.2k 100uF S3a WIPER 6.8k NTC1 IC1 TEA1100 10 .033 NTC2 1.8k 10uF The output from IC2 drives complementary pair Q2 & Q3 which in turn provide the current pulses to drive the gate of Q1. Q1 is used to switch the N1 winding of transformer T1. This transformer has a turns ratio (N1:N2) of 1:1.7, to provide suffi­cient voltage step-up for recharging battery packs above 12V. Diode D1, an MBR735 fast recovery type, rectifies the transformer output so that the battery is charged with the correct polarity. The charge current through the batteries is sensed by the two 0.1Ω 5W resistors and the voltage developed across them is fed via one of five resistors, as selected by S2, to op amp A1 inside IC1 (at pin 5). This op amp compares the voltage developed across the current sensing resistors and produces an error signal to control the PWM oscillator. This, in turn, adjusts the PWM output signal at pin 1 so that the charging current is correct. The .01µF capacitor at pin 5 filters out any transient voltages which could otherwise cause false current settings. In addition, the output of error amplifier A1 is fil­tered using a 47kΩ resistor and a .001µF capacitor at pin 4. As the battery charges, its voltage is monitored via a voltage divider network (56kΩ & 15kΩ). The resulting voltage sample is filtered using a 1µF capacitor and applied to pin 7 (VAC) of IC1. When the battery is fully charged, the IC detects the slight drop in battery voltage and automatically switches to the trickle mode as described above. Power for the circuit is fed from a 12V car battery via fuse F1. This fuse protects against shorts and reverse polarity connections. If the 12V battery is wrongly connected, an internal reverse diode in Q1 will conduct and blow the fuse. tor and transistors Q2 & Q3 can now be installed. Make sure that these parts are all correctly oriented and don’t get the two transistors mixed up. REG1 must be installed with its metal tab towards ZD1. Diode D1 and transistor Q1 are installed with their metal tabs towards the edge of the board. Install them with their mounting holes about 22mm above the board, so that they can later be bolted to the rear panel. Next, install the capacitors on the board, starting with the smaller devices and finishing with the three 4700µF electrolytics. The temperature sensing feature may not be needed for some applications. If you don’t wish to use it, connect a 100kΩ resistor across the NTC1 and NTC2 terminals. Winding the transformer The PC board is secured to integral standoffs in the base of the case using four self-tapping screws. Note the use of plastic cable ties to beep the internal wiring neat and tidy. The 12V rail is decoupled using three 4700µF capacitors and two 0.47µF capacitors. These provide the high current pulses required by T1. A 10Ω resistor and 16V zener diode ZD1 protect IC2 from high voltage transients on the 12V rail, while 3-termi­nal regulator REG1 supplies 8V to IC1. In addition, the output of REG1 supplies power to LED 1, the other side of which is connect­ed to pin 15 of IC1 via a 1kΩ current limiting resistor. Construction Most of the parts for the Extra Fast Nicad Charger are mounted on a PC board coded 14309951 and measuring 11 12 13 14 15 16 17 18 19 171 x 140mm. Fig.3 shows the parts layout. Begin by carefully checking the PC board against the pub­lished pattern. In particular, check for broken or shorted tracks. When you are satisfied that the board is OK, begin the assembly by installing PC stakes at all the external wiring points (19 in all). This done, install the wire links, followed by the ICs and the resistors. Table 1 shows the resistor colour codes but it is always a good idea to check them using a digital multimeter, as some colours can be difficult to read. The zener diode, 3-terminal regula- Transformer T1 is wound using 0.8mm-diameter enamelled copper wire – see Fig.4. Begin by cutting four 1700mm lengths of wire and soldering these to pins 9, 8, 7 and 6 of the transformer bobbin. This done, wind these four wires together (ie, side-by-side) onto the bobbin in the direction indicated until you have completed 24 turns. Terminate the free ends to pins 12, 13, 14 & 15 respectively (ie, 9 to 12, 8 to 13, etc), then insulate the winding with a single layer of paper held with insulating tape. Next, cut two 3500mm lengths of wire and connect these to pins 2 & 3. These two wires are then wound on together for 41 turns in the same direction as the previous winding – see Fig.4. Terminate their free ends on pins 19 & 18 (ie, 2 to 19; 3 to 18) and again CASE 20 HEATSINK PRIMARIES SECONDARIES FINISH FINISH T1 WINDINGS VIEWED FROM BELOW NUT WASHER INSULATING BUSH TO3P (TO220) DEVICE MICA WASHER 3mm SCREW PRIMARY : 4x0.8mm DIA ENCW 24T SECONDARY : 2x0.8mm ENCW 41T PRIMARIES START 10 9 8 7 6 SECONDARIES START 5 4 3 2 Fig.4: this diagram shows the winding details for transformer T1 (see text). 1 Fig.5: here are the mounting details for Mosfet (Q1) and the fast recovery diode (D1). They must be isolated from the case and the heatsink using TO-220 mounting kits. October 1995  59 F1 RED+ SOLDER LUG CORD GRIP GROMMET D1 CORD GRIP GROMMET Q1 D RE C1 NT CK LA C2 -B D NT CA NI BLACKNICAD+ RED 1 NTC2 NTC1 S1 B 12 1 A 5 1 2 K LED1 S3 A 60  Silicon Chip 3 4 S2 Fig.6: use this diagram to complete the wiring to the switch­es and the PC board. Tucked in behind the 4700µF filter capacitors are the T0220 Mosfet and fast recovery diode. The mounting details for these devices are shown in Fig.5. finish with a layer of paper held with insulating tape. The transformer can now be assembled by first inserting one ferrite core half into the bobbin and installing its metal re­taining clip. The other ferrite core half is then inserted and 0.5mm spacers (eg, 4 x TO-220 mica washers) slid in between the two halves to provide an air gap (see photo). The second core half is then secured by installing its retaining clip. Once the transformer assembly has been completed, it can be installed on the PC board. Make sure that pin 1 is adjacent to the 56kΩ resistor. Final assembly The Extra Fast Nicad Charger is housed in a plastic case measuring 204 x 68 x 157mm. An aluminium panel The charger has optional temperature monitoring of the battery provided by a negative temperature coefficient (NTC) thermistor. measuring 194 x 65mm and a finned heatsink (125 x 42 x 34mm) are fitted at the rear. Position the PC board in the case and line up its mounting holes on the four integral standoffs at the corners. Use a large drill to shorten the unused standoffs so that the PC board will sit neatly in position. This done, secure the PC board in place with self-tapping screws, slide the metal panel into the slot at the rear of the case, and mark the positions for the Mosfet and diode mounting holes. Next, drill these holes in the rear panel, along with holes for the two cord­grip grommets and the fuseholder. The heatsink is also secured with a screw and nut at its centre. After all the holes have been drilled, remove any burrs, particularly around the Mosfet and diode mounting holes, to prevent punch-through of the insulating washers. The heatsink can now be secured to the rear panel using its central mounting screw. Fit an earth solder lug to this mounting screw and apply a smear of heatsink compound between the mating faces of the heatsink and rear panel before the final assembly. Fig.5 shows the mounting details for the the Mosfet transistor and diode D1. They each need to be isolated from the panel using an insu­lating washer and bush. If you are using mica washers, use a smear of heatsink compound between the mating faces before final assem­ b ly. If silicone-impregnated glass fibre washers are used, no heatsink compound is necessary. When you have tightened down the screw TABLE 1: RESISTOR COLOUR CODES ❏ No. ❏  1 ❏  1 ❏  2 ❏  1 ❏  1 ❏  1 ❏  1 ❏  1 ❏  1 ❏  2 ❏  1 ❏  1 ❏  1 ❏  1 ❏  3 Value 220kΩ 100kΩ 56kΩ 47kΩ 27kΩ 15kΩ 6.8kΩ 4.3kΩ 3.9kΩ 2.2kΩ 2kΩ 1.8kΩ 1.1kΩ 1kΩ 10Ω 4-Band Code (1%) red red yellow brown brown black yellow brown green blue orange brown yellow violet orange brown red violet orange brown brown green orange brown blue grey red brown yellow orange red brown orange white red brown red red red brown red black red brown brown grey red brown brown brown red brown brown black red brown brown black black brown 5-Band Code (1%) red red black orange brown brown black black orange brown green blue black red brown yellow violet black red brown red violet black red brown brown green black red brown blue grey black brown brown yellow orange black brown brown orange white black brown brown red red black brown brown red black black brown brown brown grey black brown brown brown brown black brown brown brown black black brown brown brown black black gold brown October 1995  61 PARTS LIST 1 plastic case, 204 x 68 x 157mm 1 aluminium rear panel, 194 x 65mm 1 heatsink, 125 x 42 x 34mm 1 PC board, code 14309951, 171 x 140mm 1 self-adhesive front panel label, 190 x 60mm 1 Philips ETD49/25/16 transformer assembly: 2 4312 020 38041 3F3 cores; 1 4322 021 33882 bobbin; 2 4322 021 33922 clips 2 0.5 x 10 x 15mm spacers to gap transformer (eg, 4 TO220 mica washers) 1 NTC thermistor (DSE Cat R-1797) 1 3AG panel fuse holder (F1) 1 10A 3AG fuse 1 SPST rocker switch (S1) (Altronics Cat S-3210) 1 single pole rotary switch (S2) 1 2-pole 6-position rotary switch (S3) 1 bezel to suit LED1 2 20mm diameter knobs 1 small cordgrip grommet 1 large cordgrip grommet 1 solder lug 2 TO-220 mounting kits 1 30A red alligator clip 1 30A black alligator clip 1 15-metre length 0.8mm enamelled copper wire 1 2-metre length automotive twin polarised cable 1 1-metre length red hookup wire 1 1-metre length black hookup wire 1 1-metre length yellow hookup wire 1 1-metre length green hookup wire 1 60mm length of 0.8mm tinned copper wire 19 PC stakes 2 25mm long x 3mm dia screws 6 cable ties and nut, use a multimeter (set to a high “Ohms” range) to confirm that the metal tab of each device is correctly isolated from the panel. Work can now be done on the front panel. Use the label as a guide for positioning the power switch, LED bezel and rotary switches. Drill out the holes for these items, then affix the label and cut out the holes with a sharp utility knife. This done, mount the switches and LED bezel on the front panel and complete the wiring in the case. If the wires passing through each grommet on the rear panel are not gripped securely, use some heatshrink tubing to increase the cable diameter. Use cable ties to keep 1 IRF540 N-channel Mosfet (Q1) 1 BC338 NPN transistor (Q2) 1 BC328 PNP transistor (Q3) 1 MBR735 Schottky diode (D1) 1 16V 1W zener diode (ZD1) 1 5mm green LED (LED1) Capacitors 3 4700µF 50VW PC electrolytic with support pin 1 100µF 16VW PC electrolytic 2 10µF 16VW PC electrolytic 1 1µF 16VW PC electrolytic 2 0.47µF MKT polyester 3 0.1µF MKT polyester 1 .033µF MKT polyester 1 .01µF MKT polyester 1 .0015µF MKT polyester 2 .001µF MKT polyester Resistors (0.25W 1%) 1 220kΩ 1 3.9kΩ 1 100kΩ 2 2.2kΩ 2 56kΩ 1 2kΩ 1 47kΩ 1 1.8kΩ 1 27kΩ 1 1.1kΩ 1 15kΩ 1 1kΩ 1 6.8kΩ 3 10Ω 1 4.3kΩ 2 0.1Ω 5W Semiconductors 1 TEA1100 nicad battery monitor (IC1) 1 7555 CMOS timer (IC2) 1 7808 3-terminal regulator (REG1) Fig.7 (below): this full size artwork can be used as a drilling template for the front panel. the wiring neat and tidy. Terminate the 12V battery leads with 30A battery clips and the nicad leads with the correct plug for your battery. The thermistor can be permanently soldered to the NTC output lead or a small 2-pin connector plug connected to the lead end. In the first case, use heatshrink tubing on the leads to prevent shorts. In the second case, the thermistor is installed EXTRA FAST NiCad CHARGER 60 90 45 30 1.8 120 180 1 + 2 Amps 1 Mins 3.5 4 + 180 120 1.4AH 2.4AH 1.8AH 62  Silicon Chip TIMEOUT (Mins) CHARGE CURRENT (Amps) 2 3.5 4 4AH 90 1AH 60 600mAH 1.2AH 45 500mAH 800mAH 1AH 30 POWER 1.8 2AH 2AH 4AH 1.4AH 2.4AH 1.8AH 2AH 1.2AH 1.4AH BATTERY CAPACITY Fig.8: this is the full size artwork for the PC board. Check your board carefully for possible etching defects before installing any of the parts. in the nicad battery package with a corresponding 2-pin socket ready for connection every time the nicad is to be charged. Fit a short length of heat­ shrink tubing over the thermistor to prevent it shorting to the nicad case. If the thermistor is not permanently installed inside the nicad pack, we recommend using either masking tape or an elastic band to hold it in con­tact with the cells during charg­ing. Testing Apply 12V to the input terminals and check that there is +8V between pins 12 and 16 of IC1. There should Specifications Maximum charge current ������������������������������������������������������������������� 4A Charge current ranges (A) �����������������������������������������������4, 3.5, 2, 1.8, 1 Charging times (mins)........................................30, 45, 60, 90, 120, 180 -dV detection ��������������������������������������������������������������������������������������1% Trickle charge current.......................... 5% of main charge current for 30 and 45 mins timeout; 2.5% for 60 and 90 mins timeout; 1.25% for 120 and 180 mins timeout Thermistor cutout temperature ������������������������������������������������������<45°C Input voltage............................................................................ 11-14VDC also be about +4.2V at pin 6 and +12V at pins 4 and 8 of IC2. The LED should be glowing dimly. If not, check the fuse and your component place­ment and wiring. If the transformer makes a high pitched squeal, check the transformer windings – they are probably wound with incorrect phase. Short out the nicad battery output leads and check that the LED flashes. The standby current with the nicad output leads shorted is about 16mA. Now the unit is ready to test by charging a battery. Switch off the power and connect a discharged nicad battery to the output leads. Select the requisite timeout period and charge current. Apply power and check that the battery charges within the allotted time. Note that the charger will not operate if the NTC output leads are disconnected from the thermistor. During charging at the higher current levels, the heatsink and transformer windings will run hot. This SC is normal. October 1995  63 NICS O R T 2223 LEC PC CONTROLLED PROGRAMMABLE POWER SWITCH MODULE This module is a four channel programmable W 0 S 1 N 9 , driver for high power relays. It can be used in 7 y le 70 any application which requires algorithm control 9, Oat Fax (02) 5 rd 8 a x C o for high power switching. This module can work Visa PO B 579 4985 as a programmable power on/off switch to limit fax a rd , ) & C 2 0 e ( r unauthorised access to equipment where the n e e o t n s h : o s a p r h P access to use or change parameters is critical. , M ith rde d o w r a d d c e This module can also be used as a universal B a n k x accepte most mix 0. Orders timer. The timer software application is ine r 1 o m $ f A ) cluded with the module. Using this software l i P a & & m r the operator can program the on/off status (ai s. P t r Z e e N n d . r ; of four independent devices in a period of o rld $10 o w 4 $ <at> a week within an accuracy of 10 minutes. . tley a Aust o : The module can be controlled through L I A M the Centronics or RS232 port. The computer is opto by E isolated from the unit, to ensure no damage can occur to the computer. Although the relays included are designed for 240V operation, they have not been approved by the electrical LEARNING - UNIVERSAL REMOTE CONTROL authorities for attachment to the mains. Power consumption These Learning IR Remote Controls can be used to replace is 7W. Main module: 146 x 53 x 40mm. Display panel: 146 up to eight dedicated IR Remote Controls: $45 x 15mm. We supply: two fully assembled and tested PCBs (main plus control panel), four relays (each with 3 x 10A / NEW CATALOGUE AT OUR WEB SITE 240V AC relay contacts), and software on 3.5" disk. We do We have combined efforts with DIY ELECTRONICS (a Hong not supply a casing or front panels. Kong based company) in producing a WEB SITE on the $92 (Cat G20) INTERNET. At this site you can view and download a text version of both of our latest catalogues and other up to date 3.5 DIGIT LCD PANEL METER information. Email orders can also be placed through here. 200mV full scale input sensitivity, “1999” count, 9 to 12V The combined effort means that you get offered an extensive <at> 1mA operation, decimal point selectable (with jumper range of over 200 high quality, good value kits, and many wire), 13mm figure height, auto polarity indicator, overrange more interesting components and items. The range of kits indication, 100Mohm input resistance, 0.5% accuracy, 2 to offered includes simple to more advanced kits, and they cover 3 readings per second. With bezel and faceplate. Dimensions: a very wide field of applications: educational, experimental, 68 x 44mm. Use in instrumentation projects. EPROM, microprocessor, computer, remote control, high $27 (Cat D01) voltage, gas and diode lasers, night vision etc. We’ll leave it to you to do the exploring at: CCD CAMERA-VCR SECURITY SYSTEM http://www.hk.super.net/~diykit This kit plus ready made PIR detector module and “learning You can also request us to send you a copy of our FREE remote control” combination can trigger any domestic IR catalogue with your next order. remote controlled VCR to RECORD human activity within a 6M range and with an 180 deg. angle of view!. Starts HELIUM-NEON LASER BARGAIN VCR recording at first movement and ceases recording Helium neon 633nM red laser heads (ie tubes sealed in a few minutes after the last movement has stopped; just a tubular metal case with an inbuilt ballast resistor) that like commercial CCD-VIDEO RECORDING systems costing were removed from equipment that is less than 5 years thousands of dollars!! CCD camera not supplied. No conold. These are suitable for light shows. Output power is in nection is required to your existing domestic VCR as the the range of 2.5-7.5mW. Heads are grouped according to system employs an “IR learning remote control”: $90 for output power range. Dimensions of the head are 380mm an PIR detector module, plus control kit, plus a suitable long and 45mm diameter. Weight: 0.6kg. A special high “lR learning remote” control and instructions: $65 when voltage supply is required to operate these heads. With purchased in conjunction with our CCD camera. Previous each tube we will include our 12V universal laser power CCD camera purchasers may claim the reduced price with supply kit MkIV (our new transformers don’t fail). Warning: proof of purchase. involves high voltage operation at a very dangerous energy level. SUPER SPECIAL: FLUORESCENT LIGHTING SPECIAL $80 for a 2.5-4.0mW tube and supply. (Cat L01) A 12V-350V DC-DC converter (with larger MOSFETS) plus a $130 for a 4.0-6.5mW tube and supply. (Cat L02) dimmable mains operated HF ballast. This pair will operate a This combination will require a source of 12V <at> at least 32-40W fluorescent tube from a 12V battery: very efficient. 2.0A. A 12V gel battery or car battery is suitable, or if 240V See June 95 EA: $36 for the kit plus the ballast. operation is required our Wang computer power supply (cat number P01) is ideal. Our SPECIAL PRICE for the Wang power STEREO SPEAKER SETS supply when purchased with matching laser head/inverter A total of four speakers to suit the making of two 2-way kit is an additional $10. speakers (stereo). The bass-midrange speakers are of good quality, European made, with cloth surround, as used in LASER WARNINGS: upmarket stereo televisions, rectangular, 80 x 200mm. The 1. Do not stare into laser beams; eye damage will result. tweeters are good quality cone types, square, 85 x 85mm. 2. Laser tubes use high voltage at dangerous energy levels; Two woofers and two tweeters: $16. be aware of the dangers. 3. Some lasers may require licensing. NEW: PHOTOGRAPHIC KITS SLAVE FLASH: very small, very simple, very effective. ARGON-ION HEADS Triggers remote flashes from camera’s own flash to fill in Used Argon-Ion heads with 30-100mW output in the blueshadows. Does not false trigger and it is very sensitive. Can green spectrum. Head only supplied. Needs 3Vac <at> 15A even be used in large rooms. PCB and components kit: $7. for the filament and approx 100Vdc <at> 10A into the driver SOUND ACTIVATED FLASH: adapted from ETI Project circuitry that is built into the head. We provide a circuit for a 514. Adjustable sensitivity & delay enable the creation suitable power supply the main cost of which is for the large of some fascinating photographs. Has LED indicator that transformer required: $170 from the mentioned supplier. makes setting up much easier. PCB, components, plus Basic information on power supply provided. Dimensions: microphone: $13. 35 x 16 x 16cm. Weight: 5.9kg. 1 year guarantee on head. Price graded according to hours on the hour meter. SINGLE CHANNEL UHF WITH CENTRAL LOCKING Argon heads only, 4-8 thousand hours: $350 (Cat L04) Our single channel UHF receiver kit has been updated to Argon heads only, 8-13 thousand hours: $250 (Cat L05) provide provision for central locking!! Key chain Tx has SAW resonator locked, see SC Dec 92. Compact receiver GEIGER COUNTER AND GEIGER TUBES has prebuilt UHF receiver module, and has provision for two These ready made Geiger counters detect dangerous Beta and extra relays for vehicle central locking function. Kit comes Gamma rays, with energy levels between 30keV and 1.2MeV. with two relays. $36. Additional relays for central locking $3 Audible counts output, also a red LED flashes. Geiger tube ea. Single ch transmitter kit $18. unplugs from main unit. To measure and record the value of nuclear radiation level the operator may employ a PC which is MASTHEAD AMPLIFIER SPECIAL connected to the detector through the RS232 interface. This High performance low noise masthead amplifier covers gives a readout, after every 8 counts, of the time between each VHF-FM UHF and is based on a MAR-6 IC. Includes two count. Main unit is 70 x 52 x 35 mm. Geiger tube housing PCBs, all on-board components. For a limited time we will unit is 135mm long and is 20mm diameter. Power from 12 also include a suitable plugpack to power the amplifier from to 14V AC or DC. mains for a total price of: $75 (Cat G17) $25 EY OATL E 64  Silicon Chip CCD CAMERA Very small PCB CCD Camera including auto iris lens: 0.1Lux, 320K pixels, IR responsive, has 6 IR LEDs on PCB. Slightly bigger than a box of matches!: $180 VISIBLE LASER DIODE KIT A 5mW/670nM visible laser diode plus a collimating lens, plus a housing, plus an APC driver kit (Sept 94 EA). UNBELIEVABLE PRICE: $40 Suitable case and battery holder to make pointer as in EA Nov 95 $5 extra. 12V-2.5 WATT SOLAR PANEL KITS These US made amorphous glass solar panels only need terminating and weather proofing. We provide clips and backing glass. Very easy to complete. Dimensions: 305 x 228mm, Vo-c: 18-20V, Is-c: 250mA. SPECIAL REDUCED PRICE: $20 ea. or 4 for $60 A very efficient switching regulator kit is available: Suits 12-24V batteries, 0.1-16A panels, $27. Also available is a simple and efficient shunt regulator kit, $5. SOLID STATE “PELTIER EFFECT” DEVICES We have reduced the price of our peltiers! These can be used to make a solid state thermoelectric cooler/heater. Basic information supplied: 12V-4.4A PELTIER: $25 We can also provide two thermal cut-out switches, and a 12V DC fan to suit either of the above, for an additional price of $10. BATTERY CHARGER Simple kit which is based on a commercial 12 hour mechanical timer switch which sets the battery charging period from 0 to 12 hrs. Timer clock mechanism is wound-up and started by turning the knob to the desired time setting. Linear dial with 2 hrs timing per 45 degrees of rotation, eg, 270 deg. rotation for 12 hr. setting. The contacts on the timer are used to switch on a simple constant current source. Employs a power transistor and 5 additional components. Can easily be “hard wired”. We supply a circuit, a wiring diagram, and tables showing how to select the charging current: changing one resistor value. Ideal for most rechargeable batteries. As an example most gel cells can be charged at a current which is equal to the battery capacity rating divided by 5-10. Therefore if you have a discharged gel cell that has 5Ah capacity and are using a charge current of 0.5A, the timer should be set for about 10 hours: Or 5hrs. <at> 500mA. This circuit is suitable for up to approximately 5A, but additional heatsinking would be required at currents greater than 2A. Parts and instructions only are supplied in this kit. Includes a T-03 mini fin heatsink, timer switch, power transistor and a few other small components to give you a limited selection of charge current. You will also need a DC supply with an output voltage which is greater by about 2V than the highest battery voltage you need to charge. As an example a cheap standard car battery charger could be used as the power source to charge any chargeable battery with a voltage range of 0-15V: $12 (K72) COMPUTER CONTROLLED STEPPER MOTOR DRIVER KIT This kit will drive two 4, 5, 6 or 8 wire stepper motors from an IBM computer parallel port. The motors require a separate power supply (not included). A detailed manual on the computer control of motors plus circuit diagrams and descriptions are provided. Software is also supplied, on a 3.5" disk. PCB: 153 x 45mm. Great low cost educational kit. We provide the PCB and all on-board components kit, manual, disk with software, plus two stepper motors of your choice for a special price. Choose motors from M17/M18/M35. $44 (K21) Kit without motors is also available: $32 MOTOR SPEED CONTROLLER PCB Simple circuit controls small DC powered motors which take up to around 2 amps. Uses variable duty cycle oscillator controlled by trimpot. Duty cycle is adjustable from almost 0-100%. Oscillator switches P222 MOSFET. PCB: 46 x 28mm. $11 (K67) For larger power motors use a BUZ11A MOSFET: $3. FM TX MK 3 This kit has the most range of our kits (to around 200m). Uses a pre-wound RF coil. The design limits the deviation, so the volume control on the receiver will have to be set higher than normal. 6V operation only, at approx 20mA. PCB: 46 x 33mm: $18 (K33) LOW COST IR ILLUMINATOR Illuminates night viewers or CCD cameras using 42 of our 880nm/30mW/12 degrees IR LEDs. Power output (and power consumption) is variable, using a trimpotentiometer. Operates from 10 to 15V and consumes from 5mA up to 0.6A (at maximum power). The LEDs are arranged into 6 strings of 7 series LEDs with each string controlled by an adjustable constant current source. PCB: 83 x 52mm: $40 (K36) VHF MODULATOR FOR B/W CAMERAS (To be published, EA) Simple modulator which can be adjusted to operate between about channels 7 and 11 in the VHF TV band. This is designed for use in conjunction with monochrome CCD cameras to give adequate results with a cheap TV. The incoming video simply directly modulates the VHF oscillator. This allows operation with a TV without the necessity of connecting up wires, if not desired, by simply placing the modulator within about 50cm from the TV antenna. Suits PAL and NTSC systems. PCB: 63 x 37mm: $12 (K63) SOUND FOR CCD CAMERAS/UNIVERSAL AMPLIFIER (To be published, EA). Uses an LM386 audio amplifier IC and a BC548 pre-amp. Signals picked up from an electret microphone are amplified and drives a speaker. Intended for use for listening to sound in the location of a CCD camera installation, but this kit could be used as a simple utility amplifier. Very high audio gain (adjustable) makes this unit suitable for use with directional parabolic reflectors etc. PCB: 63 x 37mm: $10 (K64) LOW COST 1 to 2 CHANNEL UHF REMOTE CONTROL (To be published, SC) A single channel 304MHz UHF remote control with over 1/2 million code combinations, which also makes provision for a second channel expansion. The low cost design has a 2A relay contact output. The 1ch transmitter (K41) can be used to control one channel of the receiver. To access the second channel when another transmitter is purchased, the other transmitter is coded differently. Alternatively, the 3ch transmitter kit (K40) as used with the 4ch receiver kit is compatible with this receiver and allows access to both channels from the one transmitter. Note that the receiver uses two separate decoder ICs. This receiver operates from 10 to 15Vdc. Range is up to about 40m. 1ch Rx kit: $22 (K26) Expansion components (to convert the receiver to 2 channel operation; extra decoder IC and relay): $6 ONE CHANNEL UHF TRANSMITTER AX5326 encoder. Transmit frequency adjustable by trimcap. Centred around 304MHz. Powered from 12V lighter battery. LED flashes when transmitting. Size of transmitter case: 67 x 30 x 13 mm. This kit is trickier to assemble than the 3ch UHF transmitter: $11 (K41) THREE CHANNEL UHF TRANSMITTER The same basic circuit as the 1ch transmitter. Two buttons, allows up to 3 channel operation. Easier to assemble than the 1ch transmitter and has slightly greater range. Size of transmitter case: 54 x 36 x 15mm: $18 (K40) ULTRASONIC RADAR Ref: EA Oct 94. This unit is designed to sound a buzzer and/or operate a relay when there is an object at a preset distance (or less) away. The distance is adjustable from 200mm to around 2.5 metres. Intended as a parking aid in a car or truck, also may be used as an aid for the sight impaired, warning device when someone approaches a danger zone, door entry sensor. PCB: 92 x 52mm. PCB, all on-board components kit plus ultrasonic transducers (relay included): $22 (K25) Optional: buzzer $3, plastic box $4. SIREN USING SPEAKER Uses the same siren driver circuit as in the “Protect anything alarm kit”, kit number K18. 4" cone/8 ohm speaker is included. Generates a really irritating sound at a sound pressure level of 95dB <at> 1m. Based around a 40106 hex Schmitt trigger inverter IC. One oscillator modulates at 1Hz another oscillator, between 500Hz and 4KHz. Current consumption is about 0.5A at 12V. PCB: 46 x 40mm. As a bonus, we include all the extra PCBs as used in the “Protect anything alarm kit”. $12 (K71) PLASMA BALL Ref: EA Jan 94. This kit will produce a fascinating colourful changing high voltage discharge in a standard domestic light bulb. The EHT circuit is powered from a 12V to 15V supply and draws a low 0.7A. Output is about 10kV AC peak. PCB: 130 x 32mm. PCB and all the on-board components (flyback transformer included), and the instructions: $28 (K16) We do not supply the standard light bulb or any casing. The prototype supply was housed in a large coffee jar, with the lamp mounted on the lid. Hint: connect the AC output to one of the pins on a fluorescent tube or a non-functional but gassed laser tube. Large non-functional laser tube or tube head: $10 ELECTROCARDIOGRAM PCB + DISK The software disk and a silk screened and solder masked PCB (PCB size: 105 x 53mm) for the ECG kit published in EA July 95. No further components supplied: $10 (K47) TOMINON HIGH POWER LENS These 230mm (1:4.5) lens have never been used. They contain six coated glass lenses, symmetric, housed in a black aluminium case. Scale range is from 1:10 through to 1:1 to 10:1. Weight: 1.6kg. Applications include high quality image projection at macro scales, and portrait photography in large formats: $45 (Cat O14) PROJECTION LENS Brand new, precision angled projection lens. Overall size is 210 x 136mm. Weight: 1.3kg. High-impact lexan housing with focal length adjustment lever. When disassembled, this lens assembly yields three 4" diameter lenses (concave, convex-concave, convex-convex). Limited quantity: $35 (Cat O15) INTENSIFIED NIGHT VIEWER KIT Reference article: Silicon Chip Sept 94. See in the dark! Make your own 3 stage first generation night scope that will produce good vision in starlight illumination! Uses 3 of the above fibre optic tubes bonded together. These tubes have superior gain and resolution to Russian viewers. 25mm size tube only weighs 390g. 40mm size tube only weighs 1.1kg. We supply a three stage fibre optically coupled image intensifier tube, EHT power supply kit which operates from 6 to 12V, and sufficient plastics to make a monocular scope. The three tubes are already bonded together: $270 for the 25mm version (Cat N04) $300 for the 40mm version (Cat N05) We can also supply a quality Peak brand 10x “plalupe” for use as an eyepiece which suits all the above 25 and 40mm windowed tubes well: $18 35mm camera lenses or either of the Russian objective lenses detailed under “Optical” suit these tubes quite well. IR “TANK” TUBE/SUPPLY KIT These components can be the basis of a very responsive infra red night viewer; the exact construction of which we leave up to you. The new IR tube is as used in older style military tank viewers. The tube employed is probably the most sensitive IR responsive tube we have ever supplied. Responds well even to 940nm LED illumination. The resultant viewer requires IR illumination, as without this it will otherwise only “see” a little bit better than the naked eye. Single tube, first generation. Screen diameter: 18mm. Tube length 95mm. Diameter: 55mm. Weight: 100g. Tube can be operated up to about 15kV. Our miniature night viewer power supply (kit number K52) is supplied with its instructions included. Only very basic ideas for construction of viewer is provided. Tube and the power supply kit only: $80 (Cat N06) RUSSIAN SCOPE KIT Our hybrid Russian/Oatley kit design makes this the pick of the Russian scopes in this price range! We supply a fully assembled Russian compact scope housing containing the intensifier tube, adjustable eyepiece and objective lens. Housing is made from aluminium. The objective lens is fixed in focus, but it is adjustable after loosening a grub screw. We also include the night viewer power supply kit (kit number K52) and a small (84 x 55 x 32mm) jiffy box to house the supply in. The box must be attached by you to the scope housing. Operates from a 9V battery. This scope has a useful visible gain but is difficult to IR illuminate satisfactorily. Length of scope is 155mm: $290 (Cat N07) LASER POINTER A complete brand new 5mW/670nM pointer in a compact plastic case (75 x 42 x 18mm) with a key chain. Features an automatic power control circuit (APC) which is similar to our kit number K35 & our laser diode module’s circuit. Battery life: 10 hours of operation. Powered by two 1.5V N type batteries (included). This item may require licensing: $80 (Cat L08) MAGNETIC CARD READER Commercial cased unit that will read some information from most plastic cards, needs 8 to 12V DC supply such as a plugpack. Draws about 400mA. Power input socket is 2.5mm DC power type. Weight: 850g. 220 x 160 x 45mm: $70 (Cat G05) 400 x 128 LCD DISPLAY MODULE - HITACHI These are silver grey Hitachi LM215 dot matrix displays. They are installed in an attractive housing. Housing dimensions: 340 x 125 x 30mm. Weight: 1.3kg. Effective display size is 65 x 235mm. Basic data for the display is provided. Driver ICs are fitted but require an external controller. New, unused units. $25 ea. (Cat D02) 3 for $60 VISIBLE LASER DIODE MODULES Industrial quality 5mW/670nM laser diode modules. Consists of a visible laser diode, diode housing, driver circuit, and collimation lens all factory assembled in one small module. Features an automatic power control circuit (APC) driver, so brightness varies little with changes in supply voltage or temperature. Requires 3 to 5V to operate and consumes approx 50mA. Note: 5V must not be exceeded and there must be no ripple on the power supply, or the module may be instantly destroyed. These items may require licensing. We have two types: 1. Overall dimensions: 11mm diameter by 40mm long. Driver board is heatshrinked onto the laser housing assembly. Collimating lens is the same as used in the above laser pointer, and our visible laser diode kit: $55 (Cat L09) 2. Overall dimensions: 12mm diameter by 43mm long. Assembled into an anodised aluminium casing. This module has a superior collimating optic. Divergence angle is less than 1milliradian. Spot size is typically 20mm in diameter at 30 metres: $65 (Cat L10) This unit may also be available with a 635nm Laser Diode fitted. FLUORESCENT LIGHT HIGH FREQUENCY BALLASTS European made, new, “slim line” cased, high frequency (HF) electronic ballasts. They feature flicker free starting, extended tube life, improved efficiency, no visual flicker during operation (as high frequency operation), reduced chance of strobing with rotating machinery, generate no audible noise and generate much reduced radio frequency interference compared to conventional ballasts. The design of these appears to be similar to the one published in the October 1994 issue of Silicon Chip magazine, in that a high frequency sine wave is used, although these are much more complex. Some models include a dimming option which requires either an external 100K potentiometer or a 0-10V DC source. Some models require the use of a separate filter choke (with dimensions of 16 x 4 x 3.2cm); this is supplied where required. We have a limited stock of these and are offering them at fraction of the cost of the parts used in them! Type A: 1 x 16W tube, not dimmable, no filter, 44 x 4 x 3.5cm: $20 Type B: 1 x 16W tube, dimmable, filter used, 43 x 4 x 3cm: $26 Type C: 1 x 18W tube, not dimmable, no filter, 28 x 4 x 3cm: $20 Type D: 2 x 32W or 36W tubes, dimmable, no filter, 43 x 4 x 3cm: $26 Type E: 2 x 32W tubes, not dimmable, no filter, 44 x 4 x 3.5cm: $22 Type F: 1 x 32W or 36W tube, not dimmable, no filter, 34 x 4 x 3cm: $20 Type G: 1 x 36W tube, not dimmable, filter used, 28 x 4 x 3cm: $20 Type H: 1 x 32W or 36W tube, dimmable, filter used, 44 x 4 x 3.5cm: $20 (Cat G09, specify type). CYCLE/VEHICLE COMPUTERS BRAND NEW SOLAR POWERED MODEL! Intended for bicycles, but with some ingenuity these could be adapted to any moving vehicle that has a rotating wheel. Could also be used with an old bicycle wheel to make a distance measuring wheel. Top of the range model. Weather and shock resistant. Functions: speedometer, average speed, maximum speed, tripmeter, odometer, auto trip timer, scan, freeze frame memory, clock. Programmable to allow operation with almost any wheel diameter. Uses a small spoke-mounted magnet, with a Hall effect switch fixed to the forks which detects each time the magnet passes. Hall effect switch is linked to the small main unit mounted on the handlebars via a cable. Readout at main unit is via an LCD display. Main unit can be unclipped from the handlebar mounting to prevent it being stolen, and weighs only 30g. Max speed reading: 160km/h. Max odometer reading: 9999km. Maximum tripmeter reading: 999.9km. Dimensions of main unit: 64 x 50 x 19mm: $32 (Cat G16) October 1995  65 COMPUTER BITS BY GEOFF COHEN gcohen<at>pcug.org.au Making the Internet connection Microsoft’s new Windows 95 includes software for access­ing the Internet. Here’s a look at how it all works. It seems that every time you open a newspaper or magazine there is an article on the Internet but they aren’t all that helpful in telling you what you need to get on-line. The popular press can’t seem to talk about anything except censorship, while the computer magazines do not usually describe exactly how to make the connection, from the point of view of a normal PC user who has little or no on-line experience. This article remedies that situation. Before going into the details, however, we’ll give a brief background on the Internet. The Internet (or Net) is the largest computer network in the world, with over 4,000,000 computers connected to it. Most PC users, except for the lucky ones who have network connections at their work or university, connect to the Net using a modem via one of the many Internet Service Providers (ISP). The Net gives access to a staggering amount of information and provides func­tions such as news­ groups (Usenet), file transfer (both download­ing and uploading), email and chat facilities (for “talking” to other Net users). How do I connect Whether you like it or not, Microsoft’s new Windows 95 is the operating system that the vast majority of PCs will be using in the future. And because it includes the necessary networking software, a large proportion of PC users will inevitably connect to the Internet from Windows 95 via the Microsoft Network (MSN). Personally, after using a preview (beta) version of Windows 95 for a few weeks, and despite some of my friends saying that I need to see a shrink, I definitely prefer it to Windows 3.11. A caveat though – I am not as impressed with the software for the Microsoft Network and I still prefer Netscape as an Internet navigator. However, I will concentrate on Micro­soft’s offering in this column. What hardware do you need to get onto the Internet? If you are going to use Windows 95 to connect to the Internet via the Microsoft Network, the minimum system you should use, without having a verrrrrry slow system would be: • Processor: 486DX2-66 CPU • Memory: 8Mb RAM (12-32Mb preferred) • Hard Disc: 250Mb absolute minimum, with 500Mb-1Gb really needed for Win 95 and Office 95. At the moment, I am using a Pentium 100 system with 32Mb RAM, a 4Gb Seagate SCSI-II hard disk, a 17-inch monitor and a 4Gb DAT tape backup. On this system, Win 95 runs very nicely indeed but this much power is not really needed. My other PC is a 486DX2-66 with 12Mb RAM and the performance is slower but still quite acceptable. I use an old fashioned mechanical switch box to allow either PC to use the modem (I really should do this in software sometime but perhaps it is another case of better never than late). Modems Fig.1: you can change the modem settings at any time by clicking on “Modem Settings” in the control panel. 66  Silicon Chip One essential item of hardware is a modem. I would not recommend buying a modem that is slower than 28,800 bps and would strongly suggest buying a V34 modem. I am currently using a VFAST modem (Maestro 288FM, 28,800 bps) but I am going to upgrade it to V34, as the VFAST protocol does not always connect at it’s maxi­mum speed when dialling some brands/ models of modems. Fig.2 (left): this is the opening screen when you first log onto the Microsoft Network. On the other hand, V34 is now a worldwide standard and should always connect at full speed (assuming a good phone line, of course). Fortunately, it is relatively cheap to upgrade my Maestro from VFAST to V34. Of course, a modem from Netcom or any other major manufacturer will also be OK (I always try to buy Australian). Setting up Win 95 After you have (probably) spent large sums of money upgrad­ing your system and have Windows 95 up and running, you need to set up “The Microsoft Network”. The setup Wizard that comes as part of the software covers this quite well. The Wizard will first ask you to set up your modem by clicking on Yes in a control panel. In my case, the Wizard only found a “Standard Modem”, so I clicked on “Change” and manually selected my modem from the list. This ensures that the maximum speed of the modem is selected. The Wizard is also useful as it finds the correct serial port. If necessary, you can change the modem settings at any time by clicking on “Modem Settings” in a control panel (see Fig.1). Next, if not already done, you will be asked to set up the Microsoft Exchange. Select “The Microsoft Network” and if you have a Fax/Modem it’s a good idea to select “Microsoft Fax”. Unless you are on a network and have Microsoft Mail, I recommend Fig.3: this is the main Microsoft Network screen (Microsoft Central). that you do not tick “Microsoft Mail”. When “The Microsoft Network” icon appears, answer the ques­tions. Note that what the Americans call the “Area or City code” we call the STD code. Also you should select the Nationwide 131400 number – this is a bit slow at 9600bps but is going to be upgraded to 14,000 very soon and to 28,800 early next year. When you connect to MSN this first time, a screen appears to tell you what is happening and the software downloads a form. You then have to fill out your personal details, as well as your credit card details, so Microsoft can get their pound (or is it kilogram now?) of flesh and charge you each month for your on-line access time. This is currently $5.00 per hour plus the local phone call to connect to MSN. When you have answered all the questions, I strongly recom­mend that you write down the Logon name and Password you select­ed. If you are sure no unauthorised person will use your account, tick the “Remember My Password” box (this saves a lot of hassles Fig.4: to access Newsgroups, you click “Categories”, then “The Inter­net Center” and browse to your heart’s content. October 1995  67 all this interesting stuff. Whenever you find a place you may want to visit again, it is an excellent idea to either make a shortcut or add it to your “Favorite Places”. This will save all the keystrokes or mouse clicks next time you want to return to the same location. Also, to make searching easier, I always select the Toolbar, as this has a few buttons, such as “Up One Level” and “MSN Central”, which make life a little easier. Remember though that this is costing you around $5.00 per hour, so you should go to Tips (see Fig.5) and learn to do as much as possible off line. You can also select File, Explore, to get a view of the Net as seen by the Windows Explorer (see Fig.6) Newsgroups Fig.5: the software includes “Tips For New Users”. You should learn to do as much as possible off line. To access Newsgroups, click “Categories”, then “The Inter­net Center” (see Fig.4). All you need to do now is click on the newsgroups you want to explore and browse to your heart’s cont­ent. Email The Inbox is where your received mail is stored. You can also select “Compose”, “New Message” to send mail to anyone in the world, provided they are on the Net. Just click on the “Send” icon when you have finished the message. Other service providers Fig.6: a view of the Microsoft Network, as seen by the Windows Explorer. This is accessed by clicking File, Explore. remembering passwords), then click on “Connect”. You then connect for the first time (see Fig.2). A popup screen asks you if you want to load the Inbox; eg, if you have some mail. When I did this, I received a welcome message from Microsoft. One nice thing about the MSN software is that you can use the normal Windows commands to view or print these messages. 68  Silicon Chip The main Microsoft Network screen (Microsoft Central) will also come up (see Fig.3). The options that I mainly use are “Categories” (for accessing the Newsgroups) and “Email”. There is also a wealth of places to visit on “MSN Today”. You only need to start clicking away to explore the Net but remember the $5.00 per hour fee – it’s very addictive and you can soon run up a sizeable bill searching through If you already have an existing Internet account which you want to use instead of, or as well as, an MSN account, and you had a 16-bit version of the software running Windows 3.11, it should run with no problems on Win 95. For example, I have Trum­pet Winsock 2.1, Netscape 1.2B5 and Free Agent 1.0 (an excellent newsreader, available at http://www.forteinc.com/ forte/agent/freagent.htm). If you want to try using 32-bit software, there is an auto­mated dialler available at http://WWW.NetEx.NET: 80//w95/windows95/internet/. This improves on the abysmal “Dial Up Networking” that Microsoft provides, which does not even have an automatic redial facility (or, at least, it was so well hidden that I couldn’t find it). Finally, readers should note that all my tests were made with a late beta version of Win 95. The final offering may give slightly different results to the screen captures shown here. SC SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Rod Irving Electronics Pty Ltd SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: Rod Irving Electronics Pty Ltd SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Rod Irving Electronics Pty Ltd SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: Rod Irving Electronics Pty Ltd SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Rod Irving Electronics Pty Ltd Digital speedom & fuel gauge 74  Silicon Chip meter Update your car’s dashboard to this fancy electronic display. It gives digital readouts of speed and the fuel remaining, and includes a 6-position overspeed alarm as well. Pt.1 – By JEFF MONEGAL Many modern cars have digital instrument panels and these are preferred by some people because they are easy to read at night. Not only that but they look fancy as well. If your car’s dashboard could do with an update, this electronic version will do the job. To simplify things as much as possible, the circuit is based on a Motorola 68705P3 microprocessor. This accepts inputs from a speed sensor, the fuel tank sender (via an A-D converter) and an overspeed switch and provides outputs to drive the dis­plays, alarm buzzer and warning lamp. The speedo display consists of a 3-digit 7-segment LED module which directly indicates the speed in km/h (kilometres per hour). An identical 3-digit display module is used for the “fuel gauge” and can display the fuel remaining in the tank in either litres, gallons or as a percentage (set during the calibration procedure). Both the speedo and fuel displays are automatically dimmed at night, so that they are not too bright. A dash-mounted “low-fuel” warning lamp lights when the reading drops below 9 (ie, below 9 litres, 9 gallons or 9%). As the amount of fuel in the tank hovers around 9, the lamp will slowly switch on and off as the fuel sloshes around in the tank. There are six overspeed alarms and these are selected by the driver using a simple rotary selector switch. The alarm speeds chosen are 62, 72, 82, 92, 102 and 120km/h. These figures were chosen to allow the driver to sit comfortably on the speed limit while still providing sufficient warning if the limit is exceeded. If the preset speed is exceeded, the circuit immediately sounds a buzzer and flashes the speedo display at a 1Hz rate (ie, once every second). This continues for as long as the preset speed is exceeded but, if necessary, the buzzer can be silenced for 30 seconds by pressing an “Alarm Mute” button. The display continues to flash even after the Alarm Mute button has been pressed, unless the speed drops back below the warning threshold. How it works Fig.1 shows the main circuit details of the Digital Dash­board. As indicated earlier, most of the action takes place inside IC2, the 68705P3 microprocessor. Crystal X1 (3.58MHz) and capacitor C8 (27pF) are the external clock components, while Q2 and IC1 are used to generate the interrupts. This circuit works as follows. When power is first applied, C1 charges via a 1MΩ 10-turn trimpot (VR1). As the voltage across C1 rises, the voltage on pin 2 of comparator IC1 eventually exceeds the 4V bias voltage on pin 3 (set by R4 & R5) and the output at pin 6 switches low. This, in turn, forward biases D4 and provides an October 1995  75 +12V +5V R4 1.5k R2 1.5k R8 47k IC1 2 TL071 4 CAL. VR1 1M PA7 2 6 S1 6 S1 1 : 62 2 : 72 3 : 82 4 : 92 5 : 102 6 : 120 C2 22 R5 6.8k 6 7 VPP TMR/BT 26 PA6 RN2 D4 1N914 7 3 C1 0.47 ALARM MUTE S2 R3 10  5 1 20 2 4 21 3 22 23 24 25 C INT 18 +5V PA1 17 5 R36 10k PA3 PA4 PA5 4 FUEL GAUGE A-D CONVERTER START CONVERSION 12 COUNT 13 END CONVERSION 14 Q3 BC548 7 E R18 100k R17 10k Q4 BC548 C B +12V B C Q5 BD679 E C10 100 LOW FUEL 12V +5V PB5 XTAL PC0 8 9 PC1 10 PC2 D6 1N914 CLK SPEED DISPLAY RESET LATCH BRIGHTNESS EXTAL R15 10k PB0 CLK PB1 RESET PB2 PC3 11 FUEL DISPLAY LATCH BRIGHTNESS 1 10 D9 1N914 PLASTIC SIDE B E E C B +12V VIA IGNITION SWITCH V+ O/P DIGITAL SPEEDO AND FUEL GAUGE C IN OUT D3 1N4004 C12 470 R7 10  ZD1 15V GND IN C3 2200 C4 2200 IC5 78L08 IC4 7805 GND OUT C13 10 C14 0.1 OUT C5 22 +8V TO FUEL GAUGE +5V C6 0.1 CHASSIS Fig.1: the circuit is based on IC2 which is a 68705P3 microprocessor. It accepts pulses from a speed sensor and the fuel gauge A-D converter and drives the speed and fuel displays. It also drives an overspeed alarm buzzer (via IC3) and a low-fuel lamp via Q4 and Q5. interrupt signal to the microprocessor (IC2) which then executes an interrupt routine in its software. IN GND VIEWED FROM BELOW I GO HALL DEVICE (SMOOTH FACE) GND 76  Silicon Chip C PB4 16 RESET 28 C7 10 R14 56k C11 0.1 R11 4 10k B +5V +5V 9 R13 1k R16 10k C8 27pF +8V IC3c 14 PB6 X1 SPEED SENSOR 8 6 IC2 68705P3 V+ HALL SENSOR O/P D7 D8 1N914 R12 CAR 1N914 15k LIGHTS D5 1N914 C9 10 PA2 RN9 +5V 5 R9 82k PA0 19 PB7 GND IC3b 3 ALARM BUZZER E E MAGNETS 2 R10 33k PB3 15 R6 10k B 1 RN1 10k RN3-RN8 Q2 BC548 27 IC3a 4093 During this interrupt routine, pin 18 (PB6) of IC2 briefly goes high and turns on Q2. This discharges C1 and thus resets the interrupt timebase. VR1 sets the timebase frequency to provide calibration of the speed display, while C2 decouples the bias voltage set by R4 & R5. A Hall Effect device is used as the speed sensor. It provides a 5V signal +8V A LED2 YELLOW R19 470  SET EMPTY VR2 1k R20 33k 2 3 TO FUEL SENDER R22 10k R26 470  6 LDR  A C16 100  LED1 +8V Q6 BC548 R25 10k B R24 100k E B R28 2.2k Q8 BC558 2 C18 100 R33 10k END OF CONVERSION R34 10k D10 1N914 7 IC7 CA3140 R31 22  C19 10 C E 3 K C +5V C R27 680k C17 4 0.47 C15 10 B R29 1k 7 IC6 CA3140  K R23 100k R21 100k R30 1k D11 1N914 6 4 SET FULL VR3 50k 4 Q9 C BC548 B 8 IC8 555 6 2 1 C21 .01 R32 10k Q7 BC548 COUNT 5 C20 .01 E R35 1k 3 START CONVERSION E +8V R19 820  SET EMPTY VR2 1k B 3 TO FUEL SENDER 2 7 IC6 CA3140 4 6 A C17 0.47 K E C VIEWED FROM BELOW R23 100k R20A 33k COMPONENTS FOR POSITIVE SENDER FUEL GAUGE A-D CONVERTER Fig.2: this circuit converts the analog output of the fuel sender to a digital signal that can be applied to the microprocessor. IC6 functions as an amplifier and this drives comparator IC7 which, in turn, controls oscillator stage IC8. at its output each time a magnet passes its sensitive area. In practice, two magnets are used and these are secured to the drive shaft of the vehicle, with the Hall Effect device mounted nearby – see Fig.7. The output from the Hall Effect device is fed to pin 17 (PB5) of IC2. Note that the output is normally pulled low via a 10kΩ resistor to ground. The signals to drive the speed display module appear at pins 8-10 (PC0-PC2) of IC2. These signal lines are labelled Clk, Reset and Latch. Note that the same Clk and Reset lines are also applied to the fuel display module. Only the Latch signals are different, the fuel display module being driven from pin 11 (PC3) of IC2. Speed buzzer & dimming Pin 27 (PA7) of IC2 is the speed alarm output. This output switches high when the vehicle’s speed exceeds the overspeed setting, as selected by switch S1. Depending on its position, S1 simply pulls one of the PA0-PA5 inputs (pins 20-25) to +5V. The remaining inputs are normally held low by 10kΩ resistors RN3-RN8 (part of a resistor array). When the set speed is exceeded and pin 27 goes high, it activates a Schmitt trigger oscillator based on IC3a. R9, R10, D5 & C9 set the oscillator frequency to about 3Hz, with the output appearing at pin 3. This drives transistor Q3 via inverter stage IC3b to pulse the buzzer on and off. IC3c is also connected as a Schmitt trigger oscillator but in this case is used as a brightness control for the two display modules. This oscillator is permanently enabled since pins 8 & 9 of IC3c are connected together. When the car’s lights are off, the duty cycle is about 50:1, as set by R13 and D9 in the feedback path. The output appears at pin 10 of IC3c and drives the blanking input (pin 4) of a 4511 display driver in each display module. If, however, the lights are turned on, D8 becomes for­ward biased which means that R12 is effectively connected in parallel with R14 each time pin 10 of IC3c goes high. This reduc­es the duty cycle to about 12:1 and this in turn considerably reduces the brightness of the displays. D7 is necessary to protect IC3 against excessive voltage (+12V) from the lights circuit. It does this by clamping the inputs of IC3c (pins 8 & 9) to the +5V rail – ie, pins 8 & 9 of IC3c can never rise above 5.6V. Low fuel lamp Q4 and Q5 control the low fuel lamp. When the microproces­sor detects low fuel (via an A/D converter), pin 15 (PB3) switch­es low. This turns Q4 off and so C10 slowly charges via R18. As the voltage across C10 rises, the voltage on the emitter of Darlington transistor Q5 also rises and so the lamp gradually turns on to full brilliance. October 1995  77 +5V 3 16 Q0 12 CLK 13 MR 10 LE CLK RESET LATCH Q1 Q2 Q3 7 9 7 1 6 2 5 6 4 IC1 4553 4 C1 .001 3 C1A C1B DIS 11 A B IC2 4511 C D BI LE 5 DS3 DS2 16 LT 8 15 R1-R7 DIS3 68  7 a a 12 6 b b a 11 4 c c f g b 10 2 d d c 9 1 ee e 15 9 f d f 14 10 g g COM 3,8 R9 120  B DIS2 3,8 3,8 E Q2 BC558 C 1 B E Q3 BC558 C B DS1 2 8 DIS1 D1 4x1N914 BRIGHTNESS Q4 BC558 C +5V D2 B D3 E E Q1 BC558 C B E C VIEWED FROM BELOW D4 R8 27k SPEEDOMETER/FUEL GAUGE DISPLAY Fig.3: the display driver circuit is based on a 4553 3-digit counter (IC1) and a 4511 BCD to 7-segment decoder (IC2). The displays are multiplexed by using IC1 to switch driver transistors Q2, Q3 and Q4 on and off at the appropriate times. Diodes D1-D4 and transistor Q1 provide leading zero blanking. Conversely, if the microprocessor detects more than 9 (gal­ lons, litres or percent) in the fuel tank, pin 15 goes high. This turns on Q4 which discharges C10 and the low fuel lamp dims to off. R18 and C10 set the lamp dimming time constant to about 10 seconds. As well as ensuring that the lamp gradually comes up to full brilliance at the low fuel point, it also prevents the lamp from rapidly fluctuating between on and off as the fuel sloshes around in the tank. Power supply Power for the circuit is derived from the car’s battery via the fusebox. D3 provides reverse polarity protection, while R7 and ZD1 provide protection against any abnormally high voltage spikes that may be present. The resulting +12V rail is then fil­tered using C3 and C4 and fed to 3-terminal regulator IC4 which provides a +5V rail. This +5V rail is used to power the ICs, the timebase cir­ cuitry and the 78  Silicon Chip LED display modules. In addition, a second 3-terminal regulator, IC5, is used to provide a +8V rail to power the A/D converter circuitry. The low-fuel lamp driver circuit (Q4 & Q5) and the buzzer driver circuit (Q3) are powered from a +12V rail derived from the input to IC4. A/D converter Fig.2 shows the fuel gauge A/D converter circuit. This circuit is necessary to convert the analog output of the existing fuel sender in the car to a digital signal that can be applied to the microprocessor (IC2). The sender in most cars consists of a rheostat with the movable arm connected to some sort of float arrangement. When the tank is full, the resistance is at minimum. Conversely, maximum resistance is obtained when the tank is empty. However, some vehicles have fuel senders that work in the opposite sense. This type of sender is catered for by making a few minor changes to the input circuitry, as shown on Fig.2. Note, however, that the circuit will not work with cars that have capacitive type fuel senders. To our knowledge, the only vehicle that uses this type of sender is the Ford Falcon range from model XD and on. Tests showed that the resistance of most senders varies from 0Ω when full to 2kΩ or more when empty. As the resistance varies, in response to a changing fuel level, the voltage applied to the inverting input (pin 2) of IC6 varies accordingly. IC6 is wired as an inverting op amp with a gain of three, as set by R23 and R20. R21 and R22 bias its non-inverting input to about 0.7V, while the amplified signal output appears at pin 6. As the fuel level falls, the voltage at pin 6 also falls and vice versa. Following IC6, the signal passes via a filter network (R27 & C18) to pin 3 of comparator stage IC7. This filter network provides a long time constant (68s) to prevent short-term fluc­tuations in the reading as the fuel sloshes around in the tank. Q8, LED 2, R29 and R30 form a constant current source and this charges C19. The resulting linear saw­ tooth YOU CAN AFFORD AN INTERNATIONAL SATELLITE TV SYSTEM This view shows the speed sensor assembly and the two magnets which are mounted on the tailshaft (or on a drive shaft). The sensor assembly is covered in heatshrink tubing and sealed with silicone sealant to make it waterproof. waveform is applied to pin 2 of IC7 and compared with the DC voltage across C18. When the microprocessor starts the conversion process, its pin 12 output (PB0) pulses high. This briefly switches on Q9 which discharges C19. As a result, pin 6 of IC7 goes high and this starts an oscillator stage based on 555 timer IC8. C19 now charges via the constant current source (Q8). When the voltage on pin 2 of IC7 rises above that on pin 3, pin 6 switches low and stops the oscillator. At the same time, it pulls pin 14 (PB2) of the microprocessor low via D10 to signal the end of conversion (EOC). Note that D10 and R33 provide 8V to 5V level translation for the microprocessor. During the conversion process, the microprocessor counts the pulses at the pin 3 output of the oscillator (IC8). This count is then processed and the resulting information used to indicate the amount of fuel in the tank. VR2 provides the zero calibration when the tank is empty, while VR3 adjusts the fre­quency of the oscillator and allows the reading to be correctly set when the tank is full. The circuit based on Darlington pair Q6 and Q7 is used only at power on. Because of the long time constant formed by C18 & R27, the fuel readout would not otherwise be accurate for several minutes when the ignition is first turned on. This problem is solved as follows. When power is first applied, C16 pulls the base of transistor Q6 high via R25. This switches on the Darlington pair (Q6 & Q7) and lights LED 3. This LED is positioned against the face of an LDR connected to pin 6 of IC6. As a result, when the LED turns on, it lowers the resistance of the LDR to SATELLITE ENTHUSIASTS STARTER KIT WARNING! The fuel gauge circuit in this design derives its input from the car’s existing fuel sender. As a result, the existing fuel gauge in the car must be disconnected and is thus rendered inoperative. If you don’t want to do this, then you might consider building only the digital speedometer section of the design. Alternatively, you can install a 2-position switch (with break before make contacts) to select between the existing fuel gauge and the digital fuel display. Finally, readers are reminded that it is illegal to tamper with a car’s odometer. In particular, it should not be disabled or removed from the vehicle. YOUR OWN INTERNATIONAL SYSTEM FROM ONLY: FREE RECEPTION FROM Asiasat II, Gorizont, Palapa, Panamsat, Intelsat HERE'S WHAT YOU GET: ● ● ● ● ● just a few hundred ohms. C18 can now charge up quite quickly via the LDR & R28 and so the correct fuel level is displayed almost immediately after the ignition is switched on. In the meantime, C16 charges via R24. After a few seconds, Q6, Q7 and LED 1 turn off and the resistance of the LDR rises to over 5MΩ. As a result, C18 now mainly charges via R27 and so the time constant is increased to over one minute to prevent fluctua­ tions due to fuel slosh as described previously. Fig.2 also shows the alternative circuit for fuel senders that work in the opposite sense to normal (ie, low resistance when the tank is empty; high resistance when the tank is full). In this case, IC6 is configured ● 400 channel dual input receiver preprogrammed for all viewable satellites 1.8m solid ground mount dish 20°K LNBF 25m coaxial cable easy set up instructions regular customer newsletters BEWARE OF IMITATORS Direct Importer: AV-COMM PTY. LTD. PO BOX 225, Balgowlah NSW 2093 Tel: (02) 9949 7417 / 9948 2667 Fax: (02) 9949 7095 VISIT OUR INTERNET SITE http://www.avcomm.com.au YES GARRY, please send me more information on international band satellite systems. Name: __________________________________ Address: ________________________________ ____________________P'code: __________ Phone: (_______) ________________________ ACN 002 174 478 October 1995  79 PARTS LIST MAIN MODULE 1 main PC board, 168 x 85mm 2 10-way ribbon cables with IDC sockets 2 10-way PC-mount IDC plugs 1 case to suit (not part of kit) 1 12V mini buzzer 2 button magnets 1 U-shaped heatsink to suit 1 6-position single-pole rotary switch (S1) 1 momentary contact pushbutton switch (S2) 1 knob to suit rotary switch 1 1MΩ 10-turn trimpot (VR1) 1 1kΩ 10-turn trimpot (VR2) 1 50kΩ 10-turn trimpot (VR3) 1 12V panel-mount lamp & bezel 1 28-pin IC socket 1 14-pin IC socket 4 8-pin IC sockets Semiconductors IC1 – TL071/TL081 op amp IC2 – 68705P3 programmed microprocessor IC3 – 4093 quad Schmitt trigger IC4 – 7805 regulator IC5 – 78L08 regulator IC6,IC7 – CA3130 op amp IC8 – 555 timer Q2,Q3,Q4,Q6,Q7,Q9 – BC548 NPN transistor Q5 – BD679 Darlington transistor Q8 – BC558 PNP transistor D3 – 1N4004 silicon diode D4,D5,D6,D7,D8,D9,D10, D11 – 1N914 silicon diode ZD1 – 15V 1W zener diode LED1 – 5mm high brightness LED LED2 – 3mm yellow LED X1 – 3.58MHz crystal 1 Hall Effect sensor Capacitors C1 – 0.47µF MKT C2,C5 – 22µF 16VW electrolytic C3,C4 – 2200µF 16VW electrolytic C6,C11,C14 – 0.1µF monolithic C7,C9,C13,C15,C19 – 10µF 16VW electrolytic C8 – 27pF ceramic C10,C16,C18 – 100µF 16VW electrolytic C12 – 470µF 16VW electrolytic C17 – 0.47µF monolithic 80  Silicon Chip C20 – .01µF MKT C21 – .01µF monolithic Resistors (0.25W, 5%) R2,R4 – 1.5kΩ R13,R29,R30,R35 – 1kΩ R3 – 10Ω R5 – 6.8kΩ R6,R11,R15,R16,R17,R22,R25, R32,R33,R34,R36 – 10kΩ R7 – 10Ω 1W R8 – 47kΩ R9 – 82kΩ R10, R20,R20a – 33kΩ R12 – 15kΩ R14 – 56kΩ R18,R21,R23,R24 – 100kΩ R19 – 470Ω or 820Ω (see test) R26 – 470Ω R27 – 680kΩ R28 – 2.2kΩ R31 – 22Ω RN1-9 – 10kΩ resistor network 1 LDR (as supplied) DISPLAY MODULE (1 each required for speedo and fuel displays) 2 PC boards, 56 x 46mm ADVERT 4 12mm spacers 1 10-way PC-mount IDC plug 1 red perspex sheet 2 16-pin IC sockets Semiconductors D1,D2,D3,D4 – 1N914 silicon diode Q1,Q2,Q3,Q4 – BC558 PNP transistor IC1 – 4553 3-digit BCD counter IC2 – 4511 BCD to 7-segment LED display driver DIS1,DIS2,DIS3 – 7-segment LED display Capacitors C1 – .001µF ceramic Resistors (1/4W, 5%) R1-R7 – 68Ω R8 – 27kΩ R9 – 120kΩ Where to buy parts Kits for this design will be available from CTOAN Electronics and this company has retained copyright of the PC board designs. as a non-inverting amplifier instead of being an inverting amplifier. The remainder of the circuit is identical. Display modules Fig.3 shows the circuit for the two display modules (ie, the speedo and fuel displays). IC1 is a 4553 3-digit counter with multiplexed outputs. It counts the pulses on its clock input from pin 8 (PC0) of the microprocessor and outputs the resulting data in BCD form. This data appears on the Q0-Q3 outputs of IC1 and drives IC2 which is a BCD to 7-segment decoder. IC2 in turn drives the a-g segments of the LED displays via current limiting resistors R1-R7. The displays are multiplexed by using IC1 to switch driver transistors Q2, Q3 and Q4 on and off at the appropriate times. A crude form of leading zero blanking is used to blank the leading digit (DIS1) when ever its value is zero. This is achieved using diodes D1-D4 and transistor Q1. D1-D4 monitor the Q1-Q4 BCD outputs of IC1. When the lead­ing digit has a value of zero, the four BCD outputs will all be low and so D1-D4 will all be reverse biased. As a result, Q1’s base is pulled low via R8 and so Q1 turns on and Q2 turns off and blanks the leading display digit. For other leading digit values, one or more of the BCD lines from IC1 will be high. Because D1-D4 effectively form a 4-input OR gate, Q1’s base will also be high. Thus, Q1 will be held off and Q2 operates as normal. Note that no blanking has been applied to the second digit (DIS2), as this would add greatly to the circuit complexity. In any case, this digit only reads “0” on the speed display when the vehicle is travelling at less than 10km/h, and “0” on the fuel display when there is less than 9 litres (or gallons, or percent) remaining in the fuel tank. The clock, latch and reset signals for the display module come from the microprocessor (IC2 on the main board), while the brightness signal comes from pin 10 of oscillator stage IC3c as described previously. Next month, we shall give the full constructional details and describe the calibration procedure. Note that several kit versions will be available SC from CTOAN Electronics. ANOTHER GREAT DEAL FROM MACSERVICE 100MHz Tektronix 465M Oscilloscope $900 2-Channel, Delayed Timebase VERTICAL SYSTEM Bandwidth & Rise Time: DC to 100MHz (-3dB) and 3.5ns or less for DC coupling and -15°C to +55°C. Bandwidth Limit Mode: Bandwidth limited to 20MHz. Deflection Factor: 5mV/div to 5V/div in 10 steps (1-2-5 sequence). DC accuracy: ±2% 0-40°C; ±3% -15-0°C, 40-55°C. Uncalibrated, continuously variable between settings, and to at least 12.5V/div. Common-Mode Rejection Ratio: 25:1 to 10MHz; 10:1 from 10-50MHz, 6cm sinewave. (ADD Mode with Ch 2 inverted.) Display Modes: Ch 1, Ch 2 (normal or inverted), alternate, chopped (250kHz rate), added, X-Y. Input R and C: 1MΩ ±2%; approx 20pF. Max Input Voltage: DC or AC coupled ±250VDC + peak AC at 50kHz, derated above 50KHz. HORIZONTAL DEFLECTION Timebase A: 0.5s/div to 0.05µs/div in 22 steps (1-2-5 sequence). X10 mag extends fastest sweep rate to 5ns/div. Timebase B: 50ms/div to 0.05µs/div in 19 steps (1-2-5 sequence). X10 mag extends maximum sweep rate to 5ns/div. Horizontal Display Modes: A, A Intensified by B, B delayed by A, and mixed. CALIBRATED SWEEP DELAY Calibrated Delay Time: Continuous from 0.1µs to at least 5s after the start of the delaying A sweep. Differential Time Measurement Accuracy: for measurements of two or more major dial divisions: +15°C to +35°C 1% + 0.1% of full scale; 0°C to +55°C additional 1% allowed. TRIGGERING A & B A Trigger Modes: Normal Sweep is triggered by an internal vertical amplifier signal, external signal, or internal power line signal. A bright baseline is provided only in presence of trigger signal. Automatic: a bright baseline is displayed in the absence of input signals. Triggering is the same as normal-mode above 40Hz. Single (main time base only). The sweep occurs once with the same triggering as normal. The capability to re-arm the sweep and illuminate the reset lamp is provided. The sweep activates when the next trigger is applied for rearming. A Trigger Holdoff: Increases A sweep holdoff time to at least 10X the TIME/DIV settings, except at 0.2s and 0.5s. Trigger View: View external and internal trigger signals; Ext X1, 100mV/div, Ext -: 10, 1V/div. Level and Slope: Internal, permits triggering at any point on the positive or negative slopes of the displayed waveform. External, permits continuously variable triggering on any level between +1.0V and -1.0V on either slope of the trigger signal. A Sources: Ch 1, Ch 2, NORM (all display modes triggered by the combined waveforms from Ch 1 and 2), LINE, EXT, EXT :-10. B Sources: B starts after delay time; Ch 1, Ch 2, NORM, EXT, EXT :-10. Optional cover for CRT screen – $35 through the vertical system. Continuously variable between steps and to at least 12.5V/div. X Axis Bandwidth: DC to at least 4MHz; Y Axis Bandwidth: DC to 100MHz; X-Y Phase: Less than 3° from DC to 50kHz. DISPLAY CRT: 5-inch, rectangular tube; 8 x 10cm display; P31 phosX-Y OPERATION phor. Graticule: Internal, non-parallax; illuminated. 8 x 10cm Sensitivity: 5mV/div to 5V/div in 10 steps (1-2-5 sequence) markings with horizontal and vertical centerlines further marked in 0.2cm increments. 10% and 90% for rise time measurements. Australia’s Largest Remarketer of markings Graticule Illumination: variable. Beam Test & Measurement Equipment Finder: Limits the display to within the graticule area and provides a visible 3167. Tel: (03) 9562 9500; Fax: (03) 9562 9590 display when pushed. MACSERVICE PTY LTD 20 Fulton Street, Oakleigh Sth, Vic., **Illustrations are representative only. Products listed are refurbished unless otherwise stated. Protect your valuable issues SILICON CHIP FLOPPY INDEX Silicon Chip Binders Now available: the complete index to all SILICON CHIP articles since the first issue in November 1987. The Floppy Index comes with a handy file viewer that lets you look at the index line by line or page by page for quick browsing, or you can use the search function. All commands are listed on the screen, so you’ll always know what to do next. Notes & Errata also now available: this file lets you quickly check out the Notes & Errata (if any) for all articles published in SILICON CHIP. Not an index but a complete copy of all Notes & Errata text (diagrams not included). The file viewer is included in the price, so that you can quickly locate the item of interest. The Floppy Index and Notes & Errata files are supplied in ASCII format on a 3.5-inch or 5.25-inch floppy disc to suit PC-compatible computers. Note: the File Viewer requires MSDOS 3.3 or above. Price $7.00 each + $3 p&p. Send your order to: Silicon Chip Publications, PO Box 139, Collaroy 2097; or phone (02) 9979 5644 & quote your credit card number; or fax the details to (02) 9979 6503. Please specify 3.5-inch or 5.25-inch disc. These beautifully-made binders will protect your copies of SILICON CHIP. ★ Heavy board covers with 2-tone green vinyl covering ★ Each binder holds up to 14 issues ★ SILICON CHIP logo printed in gold-coloured lettering on spine & cover Price: $A11.95 plus $3 p&p each (NZ $6 p&p). Just fill in & mail the order form on page 101; or fax (02) 9979 6503; or ring (02) 9979 5644 & quote your credit card number. October 1995  81 PRODUCT SHOWCASE at rates of up to 122,000 bps (bits per second). An advanced protocol error detection and message retransmission feature ensures data integrity and when used on a multiple channel system, the ter­minal has an automatic cellular chan­ nel selection feature which looks and switches to the clearest radio chan­nel. For further information, contact Information Technologies Division, Colby Demag, 75 South Creek Road, Dee Why, NSW 2099. Phone (02) 981 5555 or fax (02) 971 9643. Master stereo displays from Amber Hands-free auto-scanning Teklogix has introduced Scan-See, a new integrated barcode scanner/ re­ mote RF terminal. Weighing just over 125 grams, Scan-See is fitted to the back of the operator's hand by a Velcro strap and automatically scans bar­codes whenever they are within range (from about 40mm to 150mm). Scan-See is used in conjunction with a standard hand-held Teklogix RF terminal, which the operator places in a comfortable position, such as on their hip. Operating as a remote ex­tension of the 32-bit Teklogix RF ter­minal, ScanSee delivers sub-second response times, with data shown on a 2 x 10 LED display. For applications which require more data on the screen, a 2 x 20 LCD version is available. Two-way communication is pro­ vided through an integrated UHF FM or spread spectrum radio, with data being transmitted and received Amber Technology has announced additions to the range of DK-Audio master stereo displays, the MSD550E system with the internal monitor and activity on individual PCs can be monitored from a single work- station with a clear display and control unit. Signum Plus incorporates an in­ tegrated keyboard lock which pro­ tects the system against unauthor­ ised access and the system can function as a 19-inch chassis or bench case. Among the options available is the ability to reboot all PCs at the same time, to have chan­nel control from the PC keyboard and to position the keyboard and monitor up to 1300 metres from the PCs. For further information, contact Rican Pty Ltd, 66-76 Dickson Avenue, Artarmon, NSW 2064. Phone (02) 439 6078. Monitor and keyboard selector Signum Plus allows the control of up to eight PCs from a single keyboard and monitor. Intended for application's in PC networks and control systems, it cuts down the investment costs of up to seven keyboards and monitors, while also saving on energy, running costs and space. Additional benefits include reduced heat losses which eliminate excessive thermal loads within racks and within air-conditioning systems. A second monitor can be operated simultaneously in the 82  Silicon Chip enhanced stereo display and the MSD550LR level recorder. DK-Audio's new MSD550E offers all of the functions of the original model with the advantage of a new microproc­ essor, faster operation and greater memory capacity. The MSD550E is also fitted with stereo peak level LED indica­ tors as standard. The MSD-550E may also be ordered fit­ted with DK-Audio's FFT spectrum analyser package, an integral 1024-band Fast Fourier Transformation real time audio analyser. For further information, contact Amber Technology, Unit E, 5 Skyline Place, Frenchs Forest, NSW 2086. Phone (02) 975 1211 or fax (02) 975 1368. PC-based analog interface This recently released Analog Interface Unit (AIU) is the first in a series of easily pro­ grammed PC-based data ac­ q uisition devices to be re­ leased by Advanced R&D So­lutions. The AIU is a general purpose "dongle" sized unit that plugs directly into the parallel port on a PC. It contains an 8-bit resolution ADC and DAC with selectable true bipolar input/output ranges, entirely powered from the PC's port. Complete driver routines are supplied, to allow the user to program and create custom­ ised applications. Example programs are provided for dif­ferent languages, to show how the driver routines work. The AIU is available in kit form for $95 (incl. p&p) or $120 fully assem­ bled. For further details, contact Ad­ vanced R&D Solutions, 12 Copeland Road, Lethbridge Park, NSW 2770. Phone or fax (02) 628 1223. RF speech processor for SSB radios This product is claimed to provide an 8dB increase in signal readability in weak and noisy receive conditions for SSE transmissions - equivalent to increasing the transmitter power by four times. The difference is that this modification is legal and cheaper. The SP-100RF speech processor achieves its stated aim by virtue of the fact that the human voice is not well suited to SSE or AM radio communi­ cations which are not able to cope with large peak powers. The human voice has high amplitude peaks ac­ companied by lots of average to low level signals. It is the average to low level signals which contain most of the voice's intelligence. However, the SP- 100RF does not work by compress­ing the audio signal. Instead, it proc­esses the voice modulation at RF, using its October 1995  83 own internally generated SSE signal. This is claimed to give a cleaner output waveform and more effective "talk power". The SP-100RF, a fully assembled PC board, is priced at $121 plus freight. For more information, contact the Australian manufacturers, GFS Elect­ ronics, PO Box 97, Mitcham, Vic 3132. Phone (03) 9873 3777 or fax (03) 9872 4550. High-speed, fibre-optic GPIB extender National Instruments has announc­ ed a high-speed, software-transparent, fibre-optic GPIB extender. The GPIB-140 transfers data at up to 2.2Mb/s using the HS488 protocol and up to 1.05Mb/s using IEEE 488.1 transfers while keeping the cabling cost at a minimum. The GPIB-140 extends the maximum GPIB cable length from 20m to 1km without compro­ mising the integrity of the GPIB or requiring any application program modifications. The GPIB-140 also raises the device limit on a logical GPIB system from 15 to 26 devices. System developers can 84  Silicon Chip use the GPIB-140 to control remote printers or plotters as if they were next to the computer, isolate devices located in noisy or hazardous envi­ ronments or control factory floor tests from a remote office. For further information on the GPIB140, contact National Instruments Australia, PO Box 466, Ringwood, Vic 3134. Phone (03) 9879 9422 or fax (03) 9879 9179. Genius cordless infrared mouse Recently, we had the opportunity to use the new, battery-operated, Gen­ ius cordless HiMouse. We found it to perform well, just like a mouse should. It is slightly thicker than a Microsoft mouse, tending to lift the palm of the hand slightly and thus reducing the friction with the desk. While I pre­ ferred it, this is very subjective, as another staff member preferred the feel of the lower profile normal unit. The HiMouse comes in two parts, the cordless mouse and its cradle. The cradle has a lead which connects to the serial port, two rechargeable bat­teries, an infrared window and a slide switch to select between Microsoft and Mouse Systems modes. When the mouse is not being used it is slipped into the cradle and has its battery recharged by those in the cra­ dle, these being charged all the time the computer is turned on. The HiMouse is a 3-button unit with software provision to exchange the left and right button functions for left handers. The contoured top makes it easy to locate the three buttons. Installation was smooth and trou­blefree, taking only a matter of min­utes. The carton contains both 3.5-inch and 5.25-inch discs, to suit any model PC. The control panel, which can be made memory resident (to be called up at any time) or loaded from DOS, allows users to set the mouse sensitivity and acceleration to suit their individual applications. As well as the mouse software, a disc with a copy of Paintbrush IV, version 2, is included. While we did not use this program, the user's guide seems quite comprehensive, giving detailed steps on how to produce your own "work of art". Our only complaint concerns the battery in the mouse. Several times during the test period it went flat and while it only took a few seconds to swap it with one in the cradle, it could be a source of annoyance. In addition, the batteries are sealed in a special plastic holder and any HiMouse owner would be totally dependent on the supplier for spares. However, if you like the extra free­ dom of cordless operation, without the cord pulling the mouse in one direction, the Genius HiMouse is a boon. It has quite good operating range and it is not at all critical as far as having to be pointed at the infrared receiver in the cradle. In fact, we found you Audio Lab could point the HiMouse away at 90° to the direction of the receiver and it was still quite reliable. Many peo­ple will like it a lot. Our sample Genius HiMouse came from Rod Irving Electronics and, at the time of writing, was priced at $79. Check with any Rod Irving Pty Ltd Electron­ i cs store for the current price. (R.J.W.) harbuch<at>optusnet.com.au ANTRIM TRANSFORMERS manufactured in Australia by Harbuch Electronics Toroidal – Conventional Transformers Power – Audio – Valve – ‘Specials’ TOROIDAL Medical – Isolated – POWER Stepup/down Encased Power Supplies TRANSFORMERS Toroidal General Construction OUTER INSULATION OUTER WINDING WINDING INSULATION CORE INNER WINDING CORE INSULATION Comprehensive available: Manufactureddata in Australia Comprehensive data available www.harbuch.com.au Harbuch Electronics Pty Ltd 9/40 Leighton Pl. HORNSBY 2077 Harbuch Electronics Pty Ltd Ph (02) 476-5854 Fx (02) 476-3231 9/40 Leighton Pl, HORNSBY 2077 Ph (02) 9476 5854 Fax (02) 9476 3231 R.S.K. Electronics Pty. Ltd. Complete Audio Lab kit with PCBs, 1% resistors, PTH screened PCBs, IC sockets, boot Eprom, screen printed case, 8K RAM, 8031 processor and all ICs. Includes calibration and Audio Lab V5.1 software 10 VAC 1A plugpack plus socket $18. 2-Metre serial cable $9. $330 inc. tax. Processor test kit $15. Freight $9. Fully assembled & calibrated complete with plugpack (1-year warranty) $450 5 Ludwig Place, Duncraig, Perth WA 6023 Phone (09) 448 3787 October 1995  85 VINTAGE RADIO By JOHN HILL Vibrators – a slice of history Although crude by current standards, the vibrator made battery-operated receivers a lot more convenient to run. By using a vibrator, an expensive high-voltage “B” battery for the HT supply was no longer required. In the early days of my vintage radio collecting I bought quite a number of receivers from George, a local secondhand dealer. George had made a special effort to round up all the old radio sets he had, searching his shop and storage sheds at home to come up with what, to the uninitiated, looked like the greatest pile of junk you could possibly imagine. It’s not every day a dealer attempts to unload such a heap of “rubbish”, or finds someone who actually wants to buy it. However, George was always a reasonable man and he knew the difference between a collectible old radio and one that was only suitable for spare parts. To cut a long story short, I took the lot and they averaged out at about $4 each. Most were stripped for spares but not all of them. There was this particularly neat little Radiola mantel of late 1940s vintage. It had an attractive bakelite cabinet and I was determined that it would be restored. When I finally found time to inspect the little AWA it wasn’t quite what I thought it was. Expecting to see a 240V receiver inside the cabinet, I was disappointed to find alligator clips dangling on the end of the power cord. It was a 4-valve vibrator set and, at that stage of my radio collecting career, it was a mystery to me. The vibrator Radiola was the first receiver of that type I had encountered. After some book research, I had a better idea of what it was all about. The small AWA receiver was unusual as far as vibrator radios went because it was a 4V model as distinct from the more common 6V and 32V types. A 4V supply is nowhere near as convenient as 6V and, in order to operate the Radiola, a 6V motor cycle battery was used in conjunction with a 2Ω wirewound resistor to give the required 4V. With almost no repairs, apart from a valve replacement, the old battery receiver was working once again and it seemed to be functioning fairly well. About 20 operating hours later everything went quiet, although the vibrator was still buzzing away merrily. It was then that I started to lose interest in vibrator radios and when a 240V chassis came along, the little Radiola became a mains-pow­ered model. A clever invention This rear view of the chassis shows the vibrator’s shielded box at right. Vibrator power supplies require extensive shielding to prevent objectionable hum and RF interference. 86  Silicon Chip By modern standards, a vibrator is a fairly crude device no matter how you look at it. Yet, in its day, it was a clever invention that made battery receivers a lot easier to live with. The vibrator, or vibrator cartridge, is a plug-in device, some­what similar to a valve and made that way for much the same reason; it had a limited life and was expendable. It even used a standard valve socket, different types using 4-pin, 6-pin and 7-pin sockets. With a vibrator, it was possible to make a radio power supply which required only one battery – usually a 6V battery, similar in size to a car battery, but designed for vibrator service. Compared to a straight battery receiver This Radiola model was a popular radio receiver in the early post-war years. It was available in both mainsoperated and battery/vibrator operated versions (vibrator version shown). with 135V of dry cell “B” batteries, a vibrator set was a lot cheaper and more convenient to run, if one had the means to charge the battery. A vibrator radio uses the one power source for the valve filaments and the high tension. But everyone knows that DC cannot be transformed, so where does the high tension come from? Well, that’s where the vibrator comes in! A new 4V vibrator unit to suit the Radiola was unearthed in the author’s miscellaneous parts cupboard. Vibrators of this type would be rare items today as they went out of use with the advent of the transistor radio. The vibrator’s task is to change the low DC voltage into low voltage AC, in the form of a square wave at approximately 100Hz. This is done by using two sets of electrical contacts mounted each side of a vibrating reed. The vibrating part is similar in construction and operation to an electric buzzer or bell. The vibrator contacts switch the DC voltage alternately between opposite ends of a centre tapped transformer, so that the current flows alternately in opposite directions through the primary – see Fig.1. But while such a system does produce high AC voltages in the transformer secondary, there are disadvantages. The first problem is that because a supply generated in this way is basically a square wave, with spikes and other irreg­ ularities, plus inevitable sparking at the contacts, the system produces an incredible amount of radio frequency interference, referred to as “vibrator hash”. Numerous RF AC AC chokes and capacitors need to be employed to help suppress (but not entirely eliminate) this interference. In addition, the NON-SYNCHRONOUS VIBRATOR entire vibrator power supply REED CONTACTS NOT SHOWN must be shielded all the way Fig.1: basic scheme for a non-synchronous vibrator. The vibrator contacts from the battery clips to the switch the DC voltage alternately between opposite ends of a centre-tapped high tension output. transformer, so that the current flows alternately in opposite directions through After transforming the the primary. The resulting AC output was then fed to a rectifier. switched DC to a higher voltage, it must then be rectified and effectively filtered to smooth DC before it can be used as a HT hum-free high tension voltage. Rec­tification of the high tension voltage can be done in several ways. One way is to use a rectifier SYNCHRONOUS VIBRATOR valve as would normally be used RF INTERFERENCE SUPPRESSION COMPONENTS NOT SHOWN in a mains-operated receiver. Fig.2: the synchronous vibrator arrangement. This type of vibrator The type of vibrator that uses a employed a second set of contacts which were used to mechanically separate rectifier has two sets of rectify the high tension current in conjunction with a centre-tapped switching contacts and is known transformer secondary. as a non-synchronous vibrator. October 1995  87 Removing the cover reveals the workings of this synchronous vibrator. The solenoid unit (top) controls the vibrating reed (centre) which carries two sets of switching contacts on either side. The non-synchronous vibrator was usually used in valve car radios, together with an ordinary AC-type rectifier valve. In car radios, power consumption was of little consequence and they normally had AC-type valves throughout. Domestic vibrator radios were usually more economical in their operation and used mostly battery valves and a synchronous vibrator which has two additional sets of contacts inside it. These extra contacts are used to mechanically rectify the high tension current in conjunction with a centre tapped transformer secondary without the need for a rectifier valve – see Fig.2. This process produces a very lumpy DC voltage with a considerable amount of hash and needs very effective filtering. Because of inefficiencies – partly in the vibrator car­tridge and partly in the transformer – there were losses in the system. Also, the vibrator cartridges had a limited life. Even so, the replacement of the odd vibrator unit must have been a considerably lesser expense than the huge cost of dry cell “B” batteries. Cleaning the contacts One of the problems restorers face regarding vibrator re­ceivers is the lack of replacement vibrator units. It has been a long time since these things were used and they had relatively short life spans. However, most vibrator units can be dismantled by removing a circlip and unsoldering a metal tab. Once inside, it is not difficult to clean the contact points with a fine grade of wet and dry paper followed by a piece of clean white paper to remove any dust or abrasive particles that may be trapped Removing the vibrator assembly from its shielded box revealed a defective electrolytic capacitor and a number of paper capaci­tors, all of which needed replacing. 88  Silicon Chip in between. All contact gaps are adjustable either by screw thread or by bending. All contacts should be open when the vibrator reed is at rest except the contact that operates the reed. Point gap doesn’t appear to be critical but wide variations may affect the high tension voltage. In the case of a synchronous vibrator, the gaps should be staggered so that the primary contacts close before and open after the secondary contacts. This helps to lessen the RF interference. Not all vibrators can be serviced in such a convenient manner as some were made with similar construction techniques to that of metal valves. With this type, the vibrator contacts work in a vacuum or an inert gas. As there is no air present, the arcing at the contact points cannot form oxides with the contact material. Hence, these vacuum or gas type vibrators have a sub­stantially longer life and higher current rating, although they are throw­away items when they stop working. The old Radiola Recently, I decided to get my old Radiola vibrator radio working again, mainly because I had acquired a spare cabinet for that particular model. And as I have never written anything about vibrators in the past, it seemed like the right time to do so. Restoring the little Radiola was no different to restoring any other receiver and the usual replacement of paper and elec­trolytic capacitors was a good starting point. There are two large 400µF 12V electros in the circuit and these were practical­ly useless and needed replacing. At that stage, the receiver was working again but had a very objectionable hum in it. As there was only one high voltage electrolytic mounted on the chassis, it appeared that the other was possibly housed in the vibrator box. On removing the vibrator assembly (which is built on it own small chassis) from its shielded compartment, the elusive electrolytic was found and replaced. It was totally ineffective and had no capacitance whatsoever. The removal of the vibrator chassis revealed another four paper capacitors that were previously hidden. They too were replaced. Obviously, proper restoration cannot be done to a vibrator radio unless the vibrator and its The vibrator assembly in the old Radiola is built on its own chassis. The vibrator unit is at left, with the original faulty electrolytic capacitor immediately to its right. What looks like a paper capacitor at the top of the assembly is actually a sealed RF choke. accompanying circuitry are removed and serviced accordingly. Cleaning the vibrator contacts was straightforward and they were in excellent condition. As an added bonus, I found in my parts cupboard a new, still in its original packet, 4V vibrator bearing the same serial number as the one in the receiver. The little Radiola is perhaps one of the last few domestic vibrator radios made. All the other vibrator sets I have encoun­tered have been much older. Its valve line up is: 1R5, 1T4, 1S5 and 3V4. This is in distinct contrast to most vibrator receivers which seem to be 1930s models using 2V valves and 6V vibrators. The Radiola is the only vibrator radio I have seen with 1.4V valves and a 4V supply. No doubt there are others but they FROM NEW N CHIP O SILIC This view shows the vibrator assembly from the opposite side to the previous photo. The lower portion is occupied by the vibrator transformer. It is reasonably compact in size due to the fact that it only produces a high tension of 90V. are relatively uncommon in my area. To finish off the restoration, a new dial cord was fitted and the noisy volume control cleaned. An alignment improved the set’s performance considerably. On the subject of performance, the Radiola’s quarter watt output and small 5-inch (125mm) loudspeaker does not rate it in the “ghetto blaster” category. Now I remember why I was keen to install a 240V chassis into the AWA’s original cabinet. Even so, the little 4-valver performs surprisingly well and makes the most of its quarter watt output. It is a very sensitive re­ceiver and is capable of picking up many interstate stations in daylight hours. Finally, if you are unconcerned by originality, vibrator problems can be VINTAGE RADIO SWAP MEET 22nd October 1995 Glenroy Tech School Hall Melbourne Admission: $3 Enquiries: (054) 49 3207 overcome simply by feeding an appropriate low-level AC voltage straight into the primary of the vibrator trans­ former. This does away with both the vibrator and its accompany­ing hash. And if you are clever enough, no doubt there is a solid state alternative to the old vibrator. However, having a vibrator radio working in its original form is a much SC more satisfying restoration. 20 Electronic Projects For Cars On sale now at selected newsagents Or order your copy from Silicon Chip. Price: $8.95 (plus $3 for postage). Order by phoning (02) 979 5644 & quoting your credit card number; or fax the details to (02) 979 6503; or mail your order with cheque or credit card details to Silicon Chip Publications, PO Box 139, Collaroy, NSW 2097. October 1995  89 Silicon Chip Supply For Burglar Alarms; Low-Cost 3-Digit Counter Module; Simple Shortwave Converter For The 2-Metre Band. October 1990: Low-Cost Siren For Burglar Alarms; Dimming Controls For The Discolight; Surfsound Simulator; DC Offset For DMMs; The Dangers of Polychlorinated Biphenyls; Using The NE602 In Home-Brew Converter Circuits. BACK ISSUES September 1988: Hands-Free Speakerphone; Electronic Fish Bite Detector; High Performance AC Millivoltmeter, Pt.2; Build The Vader Voice. April 1989: Auxiliary Brake Light Flasher; What You Need to Know About Capacitors; 32-Band Graphic Equaliser, Pt.2; LED Message Board, Pt.2. May 1989: Build A Synthesised Tom-Tom; Biofeedback Monitor For Your PC; Simple Stub Filter For Suppressing TV Interference; LED Message Board, Pt.3; All About Electrolytic Cap­acitors. July 1989: Exhaust Gas Monitor (Uses TGS812 Gas Sensor); Extension For The Touch-Lamp Dimmer; Experimental Mains Hum Sniffers; Compact Ultrasonic Car Alarm. September 1989: 2-Chip Portable AM Stereo Radio (Uses MC13024 and TX7376P) Pt.1; High Or Low Fluid Level Detector; Studio Series 20-Band Stereo Equaliser, Pt.2; Auto-Zero Module for Audio Amplifiers (Uses LMC669). October 1989: FM Radio Intercom For Motorbikes Pt.1; GaAsFet Preamplifier For Amateur TV; 1Mb Printer Buffer; 2-Chip Portable AM Stereo Radio, Pt.2; Installing A Hard Disc In The PC. November 1989: Radfax Decoder For Your PC (Displays Fax, RTTY & Morse); 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); UHF Remote Switch; Balanced Input & Output Stages; Data For The LM831 Low Voltage Amplifier IC; Index to Volume 2. November 1990: How To Connect Two TV Sets To One VCR; A Really Snazzy Egg Timer; Low-Cost Model Train Controller; Battery Powered Laser Pointer; 1.5V To 9V DC Converter; Introduction To Digital Electronics; Simple 6-Metre Amateur Transmitter. January 1990: High Quality Sine/Square Oscillator; Service Tips For Your VCR; Speed­ing Up Your PC; Phone Patch For Radio Amateurs; Active Antenna Kit; Speed Controller For Ceiling Fans; Designing UHF Transmitter Stages. December 1990: DC-DC Converter For Car Amplifiers; The Big Escape – A Game Of Skill; Wiper Pulser For Rear Windows; A 4-Digit Combination Lock; 5W Power Amplifier For The 6-Metre Amateur Transmitter; Index To Volume 3. 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. January 1991: Fast Charger For Nicad Batteries, Pt.1; Have Fun With The Fruit Machine; Two-Tone Alarm Module; LCD Readout For The Capacitance Meter; How Quartz Crystals Work; The Dangers When Servicing Microwave Ovens. March 1990: 6/12V Charger For Sealed Lead-Acid Batteries; Delay Unit For Automatic Antennas; Workout Timer For Aerobics Classes; 16-Channel Mixing Desk, Pt.2; Using The UC3906 SLA Battery Charger IC. February 1991: Synthesised Stereo AM Tuner, Pt.1; Three Inverters For Fluorescent Lights; Low-Cost Sinewave Oscillator; Fast Charger For Nicad Batteries, Pt.2; How To Design Amplifier Output Stages April 1990: Dual Tracking ±50V Power Supply; Voice-Operated Switch (VOX) With Delayed Audio; 16-Channel Mixing Desk, Pt.3; Active CW Filter For Weak Signal Reception; How To Find Vintage Receivers From The 1920s. March 1991: Remote Controller For Garage Doors, Pt.1; Transistor Beta Tester Mk.2; A Synthesised AM Stereo Tuner, Pt.2; Multi-Purpose I/O Board For PC-Compatibles; Universal Wideband RF Preamplifier For Amateur Radio & TV. June 1990: Multi-Sector Home Burglar Alarm; Low-Noise Universal Stereo Preamplifier; Load Protection Switch For Power Supplies; A Speed Alarm For Your Car; Fitting A Fax Card To A Computer. April 1991: Steam Sound Simulator For Model Railroads; Remote Controller For Garage Doors, Pt.2; Simple 12/24V Light Chaser; Synthesised AM Stereo Tuner, Pt.3; A Practical Approach To Amplifier Design, Pt.2. July 1990: Digital Sine/Square Generator, Pt.1 (Covers 0-500kHz); Burglar Alarm Keypad & Combination Lock; Simple Electronic Die; Low-Cost Dual Power Supply; Inside A Coal Burning Power Station. May 1991: 13.5V 25A Power Supply For Transceivers; Stereo Audio Expander; Fluorescent Light Simulator For Model Railways; How To Install Multiple TV Outlets, Pt.1. August 1990: High Stability UHF Remote Transmitter; Universal Safety Timer For Mains Appliances (9 Minutes); Horace The Electronic Cricket; Digital Sine/Square Wave Generator, Pt.2. September 1990: Remote Control Extender For VCRs; Power June 1991: A Corner Reflector Antenna For UHF TV; 4-Channel Lighting Desk, Pt.1; 13.5V 25A Power Supply For Transceivers; Active Filter For CW Reception; Tuning In To Satellite TV, Pt.1. July 1991: Battery Discharge Pacer For Electric Vehicles; Loudspeaker Protector For Stereo Amplifiers; 4-Channel ORDER FORM Please send me a back issue for: ❏ July 1989 ❏ September 1989 ❏ January 1990 ❏ February 1990 ❏ July 1990 ❏ August 1990 ❏ December 1990 ❏ January 1991 ❏ May 1991 ❏ June 1991 ❏ October 1991 ❏ November 1991 ❏ March 1992 ❏ April 1992 ❏ August 1992 ❏ September 1992 ❏ March 1993 ❏ April 1993 ❏ August 1993 ❏ September 1993 ❏ January 1994 ❏ February 1994 ❏ June 1994 ❏ July 1994 ❏ November 1994 ❏ December 1994 ❏ April 1995 ❏ May 1995 ❏ September 1995 ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ September 1988 October 1989 March 1990 September 1990 February 1991 July 1991 December 1991 May 1992 October 1992 May 1993 October 1993 March 1994 August 1994 January 1995 June 1995 ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ April 1989 November 1989 April 1990 October 1990 March 1991 August 1991 January 1992 June 1992 January 1993 June 1993 November 1993 April 1994 September 1994 February 1995 July 1995 ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ May 1989 December 1989 June 1990 November 1990 April 1991 September 1991 February 1992 July 1992 February 1993 July 1993 December 1993 May 1994 October 1994 March 1995 August 1995 Enclosed is my cheque/money order for $­______or please debit my: ❏ Bankcard ❏ Visa Card ❏ Master Card Signature ____________________________ Card expiry date_____ /______ Name _______________________________ Phone No (___) ____________ PLEASE PRINT Street ________________________________________________________ Suburb/town ________________________________ Postcode ___________ 90  Silicon Chip Note: all prices include post & packing Australia (by return mail) ............................. $A7 NZ & PNG (airmail) ...................................... $A7 Overseas (airmail) ...................................... $A10 Detach and mail to: Silicon Chip Publications, PO Box 139, Collaroy, NSW, Australia 2097. Or call (02) 979 5644 & quote your credit card details or fax the details to (02) 979 6503. ✂ Card No. Lighting Desk, Pt.2; How To Install Multiple TV Outlets, Pt.2; Tuning In To Satellite TV, Pt.2. August 1991: Build A Digital Tachometer; Masthead Amplifier For TV & FM; PC Voice Recorder; Tuning In To Satellite TV, Pt.3; Step-By-Step Vintage Radio Repairs. September 1991: Studio 3-55L 3-Way Loudspeaker System; Digital Altimeter For Gliders & Ultralights, Pt.1; The Basics Of A/D & D/A Conversion; Windows 3 Swapfiles, Program Groups & Icons. October 1991: Build A Talking Voltmeter For Your PC, Pt.1; SteamSound Simulator For Model Railways Mk.II; Magnetic Field Strength Meter; Digital Alti­meter For Gliders & Ultralights, Pt.2; Getting To Know The Windows PIF Editor. November 1991: Colour TV Pattern Generator, Pt.1; Battery Charger For Solar Panels; Flashing Alarm Light For Cars; Digital Altimeter For Gliders & Ultralights, Pt.3; Build A Talking Voltmeter For Your PC, Pt.2. December 1991: TV Transmitter For VCRs With UHF Modulators; Infrared Light Beam Relay; Solid-State Laser Pointer; Colour TV Pattern Generator, Pt.2; Index To Volume 4. January 1992: 4-Channel Guitar Mixer; Adjustable 0-45V 8A Power Supply, Pt.1; Baby Room Monitor/FM Transmitter; Automatic Controller For Car Headlights; Experiments For Your Games Card; Restoring An AWA Radiolette. February 1992: Compact Digital Voice Recorder; 50-Watt/ Channel Stereo Power Amplifier; 12VDC/240VAC 40-Watt Inverter; Adjustable 0-45V 8A Power Supply, Pt.2; Designing A Speed Controller For Electric Models. March 1992: TV Transmitter For VHF VCRs; Studio Twin Fifty Stereo Amplifier, Pt.1; Thermostatic Switch For Car Radiator Fans; Telephone Call Timer; Coping With Damaged Computer Direct­ories; Valve Substitution In Vintage Radios. April 1992: IR Remote Control For Model Railroads; Differential Input Buffer For CROs; Studio Twin Fifty Stereo Amplifier, Pt.2; Understanding Computer Memory; Aligning Vintage Radio Receivers, Pt.1. May 1992: Build A Telephone Intercom; Low-Cost Electronic Doorbell; Battery Eliminator For Personal Players; Infrared Remote Control For Model Railroads, Pt.2; Aligning Vintage Radio Receivers, Pt.2. June 1992: Multi-Station Headset Intercom, Pt.1; Video Switcher For Camcorders & VCRs; Infrared Remote Control For Model Railroads, Pt.3; 15-Watt 12-240V Inverter; A Look At Hard Disc Drives. July 1992: Build A Nicad Battery Discharger; 8-Station Automatic Sprinkler Timer; Portable 12V SLA Battery Charger; Multi-Station Headset Intercom, Pt.2; Electronics Workbench For Home Or Laboratory. August 1992: Build An Automatic SLA Battery Charger; Miniature 1.5V To 9V DC Converter; Dummy Load Box For Large Audio Amplifiers; Internal Combustion Engines For Model Aircraft; Troubleshooting Vintage Radio Receivers. September 1992: Multi-Sector Home Burglar Alarm; Heavy-Duty 5A Drill speed Controller (see errata Nov. 1992); General-Purpose 3½-Digit LCD Panel Meter; Track Tester For Model Railroads; Build A Relative Field Strength Meter. October 1992: 2kW 24VDC To 240VAC Sine­wave Inverter; Multi-Sector Home Burglar Alarm, Pt.2; Mini Amplifier For Personal Stereos; Electronically Regulated Lead-Acid Battery Charger. January 1993: Peerless PSK60/2 2-Way Hifi Loudspeakers; Flea-Power AM Radio Transmitter; High Intensity LED Flasher For Bicycles; 2kW 24VDC To 240VAC Sine­wave Inverter, Pt.4; Speed Controller For Electric Models, Pt.3. February 1993: Three Simple Projects For Model Railroads; A Low Fuel Indicator For Cars; Audio Level/VU Meter With LED Readout; Build An Electronic Cockroach; MAL-4 Microcontroller Board, Pt.3; 2kW 24VDC To 240VAC Sine­ wave Inverter, Pt.5. March 1993: Build A Solar Charger For 12V Batteries; Alarm-Triggered Security Camera; Low-Cost Audio Mixer for Camcorders;A 24-Hour Sidereal Clock For Astronomers. April 1993: Solar-Powered Electric Fence; Build An Audio Power Meter; Three-Function Home Weather Station; 12VDC To 70VDC Step-Up Voltage Converter; Digital Clock With Battery Back-Up. May 1993: Nicad Cell Discharger; Build The Woofer Stopper; Remote Volume Control For Hifi Systems, Pt.1; Alphanumeric LCD Demonstration Board; The Micro­soft Windows Sound System. June 1993: Windows-Based Digital Logic Analyser, Pt.1; Build An AM Radio Trainer, Pt.1; Remote Control For The Woofer Stopper; Digital Voltmeter For Cars; Remote Volume Control For Hifi Systems, Pt.2 July 1993: Build a Single Chip Message Recorder; Light Beam Relay Extender; AM Radio Trainer, Pt.2; Windows Based Digital Logic Analyser; Pt.2; Quiz Game Adjudicator; Programming The Motorola 68HC705C8 Micro­controller – Lesson 1; Antenna Tuners – Why They Are Useful. For FM Microphones, Pt.1; Build a Nicad Zapper; Simple Crystal Checker; Electronic Engine Management, Pt.11. September 1994: Automatic Discharger For Nicad Battery Packs; MiniVox Voice Operated Relay; Image Intensified Night Viewer; AM Radio For Aircraft Weather Beacons; Dual Diversity Tuner For FM Microphones, Pt.2; Electronic Engine Management, Pt.12. October 1994: Dolby Surround Sound – How It Works; Dual Rail Variable Power Supply (±1.25V to ±15V); Talking Headlight Reminder; Electronic Ballast For Fluorescent Lights; Temperature Controlled Soldering Station; Electronic Engine Management, Pt.13. November 1994: Dry Cell Battery Rejuv­enator; A Novel Alphanumeric Clock; 80-Metre DSB Amateur Transmitter; Twin-Cell Nicad Discharger (See May 1993); Anti-Lock Braking Systems; How To Plot Patterns Direct To PC Boards. August 1993: Low-Cost Colour Video Fader; 60-LED Brake Light Array; A Microprocessor-Based Sidereal Clock; The Southern Cross Z80-Based Computer; A Look At Satellites & Their Orbits. December 1994: Dolby Pro-Logic Surround Sound Decoder, Pt.1; Easy-To-Build Car Burglar Alarm; Three-Spot Low Distortion Sinewave Oscillator; Clifford – A Pesky Electronic Cricket; Cruise Control – How It Works; Remote Control System for Models, Pt.1; Index to Vol.7. September 1993: Automatic Nicad Battery Charger/ Discharger; Stereo Preamplifier With IR Remote Control, Pt.1; In-Circuit Transistor Tester; A +5V to ±15V DC Converter; Remote-Controlled Cockroach; Servicing An R/C Transmitter, Pt.1. January 1995: Build A Sun Tracker For Solar Panels; Battery Saver For Torches; Dolby Pro-Logic Surround Sound Decoder, Pt.2; Dual Channel UHF Remote Control; Stereo Microphone Preamplifier; The Latest Trends In Car Sound; Pt1. October 1993: Courtesy Light Switch-Off Timer For Cars; Wireless Microphone For Musicians; Stereo Preamplifier With IR Remote Control, Pt.2; Electronic Engine Management, Pt.1; Programming The Motorola 68HC705C8 Micro­ controller – Lesson 2; Servicing An R/C Transmitter, Pt.2. February 1995: 50-Watt/Channel Stereo Amplifier Module; Digital Effects Unit For Musicians; 6-Channel Thermometer With LCD Readout; Wide Range Electrostatic Loudspeakers, Pt.1; Oil Change Timer For Cars; The Latest Trends In Car Sound; Pt2; Remote Control System For Models, Pt.2. November 1993: Jumbo Digital Clock; High Efficiency Inverter For Fluorescent Tubes; Stereo Preamplifier With IR Remote Control, Pt.3; Siren Sound Generator; Electronic Engine Management, Pt.2; Experiments For Games Cards. March 1995: 50W/Channel Stereo Amplifier, Pt.1; Subcarrier Decoder For FM Receivers; Wide Range Electrostatic Loudspeakers, Pt.2; IR Illuminator For CCD Cameras & Night Viewers; Remote Control System For Models, Pt.3; Simple CW Filter. December 1993: Remote Controller For Garage Doors; Low-Voltage LED Stroboscope; Low-Cost 25W Amplifier Module; Build A 1-Chip Melody Generator; Electronic Engine Management, Pt.3; Index To Volume 6. January 1994: 3A 40V Adjustable Power Supply; Switching Regulator For Solar Panels; Printer Status Indicator; Mini Drill Speed Controller; Stepper Motor Controller; Active Filter Design For Beginners; Electronic Engine Management, Pt.4. February 1994: 90-Second Message Recorder; Compact & Efficient 12-240VAC 200W Inverter; Single Chip 0.5W Audio Amplifier; 3A 40V Adjustable Power Supply; Electronic Engine Management, Pt.5; Airbags – How They Work. March 1994: Intelligent IR Remote Controller; Build A 50W Audio Amplifier Module; Level Crossing Detector For Model Railways; Voice Activated Switch For FM Microphones; Simple LED Chaser; Electronic Engine Management, Pt.6. April 1994: Remote Control Extender For VCRs; Sound & Lights For Model Railway Level Crossings; Discrete Dual Supply Voltage Regulator; Low-Noise Universal Stereo Preamplifier; Build A Digital Water Tank Gauge; Electronic Engine Management, Pt.7. May 1994: Fast Charger For Nicad Batteries; Induction Balance Metal Locator; Multi-Channel Infrared Remote Control; Dual Electronic Dice; Two Simple Servo Driver Circuits; Electronic Engine Management, Pt.8; Passive Rebroadcasting For TV Signals. June 1994: 200W/350W Mosfet Amplifier Module; A Coolant Level Alarm For Your Car; An 80-Metre AM/CW Transmitter For Amateurs; Converting Phono Inputs To Line Inputs; A PC-Based Nicad Battery Monitor; Electronic Engine Management, Pt.9 July 1994: SmallTalk – a Tiny Voice Digitiser For The PC; Build A 4-Bay Bow-Tie UHF Antenna; PreChamp 2-Transistor Preamplifier; Steam Train Whistle & Diesel Horn Simulator; Portable 6V SLA Battery Charger; Electronic Engine Management, Pt.10. August 1994: High-Power Dimmer For Incandescent Lights; Microprocessor-Controlled Morse Keyer; Dual Diversity Tuner April 1995: Build An FM Radio Trainer, Pt.1; Photographic Timer For Darkrooms; Balanced Microphone Preamplifier & Line Filter; 50W/Channel Stereo Amplifier, Pt.2; Wide Range Electrostatic Loudspeakers, Pt.3; 8-Channel Decoder For Radio Remote Control. May 1995: Introduction To Satellite TV; CMOS Memory Settings – What To Do When the Battery On Your Mother­ board Goes Flat; Mains Music Transmitter & Receiver; Guitar Headphone Amplifier For Practice Sessions; Build An FM Radio Trainer, Pt.2; Low Cost Transistor & Mosfet Tester For DMMs; 16-Channel Decoder For Radio Remote Control. June 1995: Build A Satellite TV Receiver; Train Detector For Model Railways; A 1W Audio Amplifier Trainer; Low-Cost Video Security System; A Multi-Channel Radio Control Transmitter For Models, Pt.1; Build A $30 Digital Multimeter. July 1995: Low-Power Electric Fence Controller; How To Run Two Trains On A Single Track (Plus Level Crossing Lights & Sound Effects); Setting Up A Satellite TV Ground Station; Build A Reliable Door Minder; Adding RAM To Your Computer; Philips’ CDI-210 Interactive CD Player. August 1995: Vifa JV-60 2-Way Bass Reflex Loudspeaker System; A Fuel Injector Monitor For Cars; Gain Controlled Microphone Preamp; The Audio Lab PC Controlled Test Instrument, Pt.1; The Mighty-Mite Powered Loudspeaker; An Easy Way To Identify IDE Hard Disc Drive Parameters. September 1995: Build A Keypad Combination Lock; The Incredible Vader Voice; Railpower Mk.2 Walk-Around Throttle For Model Railways, Pt.1; Build A Jacob’s Ladder Display; The Audio Lab PC Controlled Test Instrument, Pt.2; Automotive Ignition Timing, Pt.1; Running MemMaker & Avoiding Memory Conflicts. PLEASE NOTE: November 1987 to August 1988, October 1988 to March 1989, June 1989, Aug­ust 1989, May 1990, November 1992 and December 1992 are now sold out. All other issues are presently in stock. For readers wanting articles from sold-out issues, we can supply photostat copies (or tear­sheets) at $7.00 per article (includes. p&p). When supplying photostat articles or back copies, we automatically supply any relevant notes & errata at no extra charge. October 1995  91 ASK SILICON CHIP Got a technical problem? Can’t understand a piece of jargon or some technical principle? Drop us a line and we’ll answer your question. Write to: Ask Silicon Chip, PO Box 139, Collaroy Beach, NSW 2097. Request for high quality class-A amplifier I have just purchased your “Dolby Pro-Logic Surround Sound Decoder”, as featured in the December 1994 & January 1995. Con­gratulations to you and all those involved in this project. It must have been very time consuming to develop. I have also read your Publisher’s Letter (July 1994) where you stated that valve amplifiers are “dead and buried”. Well, that statement floored me and I’ve only just recovered. There is a publication called Hi-Fi World that bases its whole existence on valve amplifiers, particularly the single- ended types using 300Bs and 211s, etc. Some valve amplifiers sell for $34,500 each. They have silver wire wound output transformers, silver foil capacitors, etc, and they possess an openness and are soni­cally superior to any transistor amplifier ever built. Well, we have all read and heard this, and I have heard these single-ended mono-blocks and believe me they do sound good. Well, that’s fine and like you say, they are dead and buried, for the average audiophile like me and many others. But to complement your beautiful project, the Dolby Pro-Logic Sur­round Sound Decoder, could you Locomotive compressor sound generator Could you come up with another train sound effects circuit? Train sound effects have just about been fully covered you would think. Not so! One that hasn’t been done anywhere to my knowledge is the resonating, intermittent, boomboom noise of the exhaust of the Westing­ house air compressor on steam locos such as the C36. The sound has a peculiar deep resonating quality and is quite loud and 92  Silicon Chip see if there would be enough interest for you to design a single-ended class A transistor amplifier, having all those qualities that valve amplifiers possess. This kit would not be cheap and why should it when European kits (valve) start at $4000. The capacitors, transistors and other vital parts would have to be sourced from all over the world, or would they? Perhaps there are manufacturers right here in Australia that could be interested in this project. Why is it that the “high end” components come from overseas? (R. L., Somerville, Vic) • We stick to our contention that valve amplifiers are no longer relevant. You should understand that very highpriced amplifiers and other equipment have little or no performance edge over the best mass-produced equipment. In many cases, particular­ly where valves are used, they are inferior. Amplifiers costing $34,500 are designed merely to separate very rich ignorant people from their money. Both Tortech Pty Ltd and Harbuch Electronics Pty Ltd, advertisers in our magazine, are able to wind high quality trans­formers to order. As far as we know, capacitors are no longer being made in Australia, so they all need to come from overseas. Our experience with high priced amplifier kits is that very few people can afford to build distinctive. It is typical of what one would expect when a large pulse of air under high pressure is released into a large hollow steel vessel. I would have a go at it myself with a simple oscillator circuit but the resonating boom quality (fairly low frequency) is something I don’t know how to create. In fact, it ought to be relatively easy – certainly much easier than simulating the throb and superimposed whine of a diesel, and that has been done a number of times to my knowledge. (P. D., Orange, NSW). them. And most of those who can afford a high priced kit would rather go and buy the finished product. Electric fence needs more bite I recently bought the electric fence controller kit that was published in SILICON CHIP, July 1995. I assembled the kit, checked the values of all components and it worked first time. However, I was rather disappointed with the zap that the unit put out. Compared to a cheap commercial unit our neighbour has, it is only a tingle and as soon as rain fell, it would not work but the neighbours’ unit on my line worked fine in the wet. My unit has not got the zap I expected it to have and the horses appear unperturbed by it. So I do not think it is suitable for control­ling livestock. I have made a couple of modifications to the circuit which make it work a lot better and give a similar zap to the cheap commercial unit. I added one 2.2Ω resistor and one 1000µF capaci­ tor in the positive supply to the coil and a diode between the coil and the output transistor. My scope is only an old 10MHz unit and it is difficult to measure the fast rise time and the voltages involved correctly. My main questions and reason for writing is • We think it would be very difficult to simulate the sound of a locomotive’s air compressor directly with electronic circui­try. To produce a really authentic sound, it would be better to record the sounds of the real locomotive and then store them in one of the solid state message recorder chips. You could use the 16-second chip described in the July 1993 issue or the 90 second version described in the February 1994 issue. We do have back issues available at $7 each, including postage. to find out if the modifications made would be outside the standards set down and whether they may be dangerous. (B. I., Riverside, Tas). • The Australian Standards require that the output voltage must not exceed 5kV when the high tension output is loaded via a 1MΩ resistor to ground. We set the duration of charge for the ignition coil so that it did not produce greater than 5kV. Your modifications may have altered the controller so that it produces a higher voltage. We are not sure what effect the diode in series with the coil driving transistor has, except to reduce the coil current due to its voltage drop. The 1000µF capacitor and 2.2Ω resistor will have the effect of increasing the coil current during charging to result in higher output. The same effect could be achieved by reducing the value of the 6.8Ω resis­tor in series with the coil. Check the voltage swing from the coil with a 1MΩ resistive load. This will need to withstand at least 5kV and since 0.5W resistors normally have a DC rating of only 350V, you will need a series string of at least 15 resistors. Even with 15 resistors you may have problems because the fast-rising voltage pulse may break over the resistors. How to produce a black screen I constructed the colour TV pattern generator (SILICON CHIP, November & December 1991) some time ago and found it works exceptionally well but I wish to modify the unit to generate a black screen. However, I am unsure how to do this properly. I understand that IC15 (74HC193) will generate black when all the Q outputs are grounded and the cathodes of D5, D6 & D7 go low; the clock signal to IC15 is thus disabled and the black signal from IC16 continues until the next blanking period. Does this mean that the blanking signal must be interrupted? (D. B., Redland Bay, Qld). • A black screen can be obtained by selecting the red raster pattern and tying pin 1 of IC15 low via a switch. This will set all colour inputs to IC16 (red, green and blue) low for a black signal. The colour burst and sync pulses will be taken care of with the sync and blank inputs on IC16. LED  1 MOC3021 390  .033 250VAC  2 470  6 4 22  1W A2 G A1 330 0.1 250VAC 0.1 250VAC L1 GPO A N E CASE N 240VAC A Fig.1: this circuit shows the additional snubber components which should be added to the Discolight to ensure reliable commutation of the Triac and the optocoupler. Discolight with neon lighting I have built your Discolight project as described in the July & August 1988 issues. I am using it as a chaser to drive neon lighting transformers. Trouble is, the Triacs appear to be getting very hot and two of the suppression inductors have defi­nite signs of overheating; ie, they are discoloured. The neon transformers have a rating of 10kV at 25mA. Since I am using the project only in chaser mode, whereby it operates with zero vol­ tage switching, I cannot see why there should be any problem with power dissipation in the Triacs. Can you offer any clues as to what the trouble may be? (G. S., Bendigo, Vic). • Those neon transformers represent a very severe inductive load which the Discolight was never intended to drive. For reli­ a ble commutation (ie, switching off) of inductive loads, Triacs must be fitted with snubber networks. This is an RC network connected between the A1 & A2 terminals to effectively make the load more resistive rather than inductive. We used a snubber network connected across a Triac in the High Power Dimmer fea­ tured in the August 1994 issue of SILICON CHIP. This network consisted of a 22Ω 1W resistor in series with a 0.1µF 250VAC capacitor. You would need to connect this snubber network across each of the four Triacs in the Discolight. Each MOC3021 opto­cou­pler requires a snubber too. The accompanying diagram shows a .033µF capacitor in association with 470Ω and 390Ω resistors. Apart from the snubber networks, it is usual practice to connect an incandescent lamp (40W minimum) to each channel to provide a minimum resistive load for the Triacs. However, having said all that, the fact that the interfer­ence suppression inductors are overheating suggests that there is a much higher current being passed than should be the case; ie, amps and amps. The nominal rating of the neon transformers may be only 250VA (ie, 10kV x 25mA) but are you running several of these on each channel? We wonder if your application might be better served by the Four Channel Lighting Desk featured in the June & July 1991 issues. This featured 40A Triacs and much bigger interference suppression inductors. It too would require the addition of snubber networks but you would have more room to do it. October 1995  93 MARKET CENTRE Cash in your surplus gear. Advertise it here in Silicon Chip. CLASSIFIED ADVERTISING RATES FOR SALE Advertising rates for this page: Classified ads: $10.00 for up to 12 words plus 50 cents for each additional word. Display ads (casual rate): $25 per column centimetre (Max. 10cm). Closing date: five weeks prior to month of sale. To run your classified ad, print it clearly in the space below or on a separate sheet of paper, fill out the form & send it with your cheque or credit card details to: Silicon Chip Classifieds, PO Box 139, Collaroy, NSW 2097. Or fax the details to (02) 979 6503. INVERTERS 12V-230VAC 90% EFFICIENCY. Modified Sine Wave. Compact 55 x 160 x 98mm. Light 800gm. Standby 50mA/0.6W. 100 Watt Continuous $99. 200 Watt $149. A.S.S. (09) 349 9413, fax (09) 344 5905. _____________ _____________ _____________ _____________ _____________ INFRA-RED CORDLESS RECHARG­ EABLE STEREO HEADPHONES. 20Hz-20kHz. Lightweight. $69. A.S.S. (09) 349 9413, fax (09) 344 5905. _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ TINY 2/3 MATCHBOX SIZE VIDEO CAMERA MODULES $169. RF MODULATOR $30. Patch these into your TV Antenna System Display and/or Record on all TVs & VCRs. VERY FLEXIBLE & PRACTICAL VIDEO SUR­VEILLANCE PACKAGE only $199. Camera 400+ TVL, 35 x 35 x 25mm incl Lens, Auto Iris, Infra-Red & Low Light Sensitive. IR LEDs 50mW pkt/30 $15 SEE IN TOTAL DARKNESS. A.S.S. (09) 349 9413, fax (09) 344 5905. D.I.Y. PACKAGED CCTV SYSTEMS. $699. 10" Monitor 4 Ch Switcher, Camera, 20M Cable & Stand PLUG-IN & GO! Features Two-Way Inter­com, Alarm I/Ps, VCR I/O, 400 TVL 0.2 Lux Low Light & IR Sensi­tive Camera. A.S.S. (09) 349 9413, fax (09) 344 5905. CLOSED CIRCUIT VIDEO EQUIPMENT. Mono & Colour Cameras incl. Lens from $249. 32 x 32 x 15mm Enclosed is my cheque/money order for $­__________ or please debit my RCS RADIO PTY LTD Card No. ✂ ❏ Bankcard   ❏ Visa Card   ❏ Master Card Signature­­­­­­­­­­­­__________________________ Card expiry date______/______ Name ______________________________________________________ Street ______________________________________________________ Suburb/town ___________________________ Postcode______________ 94  Silicon Chip RCS Radio Pty Ltd is the only company that manufactures and sells every PC board and front panel published in SILICON CHIP, ETI and EA. RCS Radio Pty Ltd, 651 Forest Rd, Bexley 2207. Phone (02) 587 3491 CONCEALED PINHOLE Modules from $239. 4 & 8 Ch Quad & Freeze Screen Splitters & Switchers from $239. Combination Modulator/Antenna Boosters to Display/Record Video on TV/VCR. Video Microscopes 10X to 1000X. Discounts 10% - 37.5%. A.S.S. (09) 349 9413, fax (09) 344 5905. PROMO DISK OF SHORT FORM KITS $2 coin. PIC16C5x/71/84 Uni-PCB $20, BasicMicro-1 PCB+Chipset $65, PIC84 Prog/Run PCB $20, PIC84 EEPROM CPU $15, COM1 driven 18 I/O $57, LPT1 driven 64 I/O $35, Z80Dev $35, Z80A+Xt1 $4, Z80B+Xt1 $6, LPT1 Cable $3, 20x2716 $10, PIC16Cxx Prod. Programmer $225. donmck<at>tbsa.com.au MicroZed has second source authorised BASIC STAMP alternative. Double and quad speed option available. EDUCATIONAL ELECTRONIC KITS: easy to build. Good quality. Up-to-date technology. Cheap. Guaranteed to work. Wide range selection. Send $2.00 in stamps for catalogue and price list. Or log onto our BBS FREE for full details of every kit. DIY ELECTRONICS, 22 McGregor Street, Numurkah, Vic 3636. Ph/Fax (058) 62 1915. Ph/BBS (24hr) (058) 62 3303. ADD AN IBM KEYBOARD DECODER (EA, Dec. 90) to your project. 8 left. PCB, Programmed 8749 & Disk $20. 15 Romloader 256K upgrade PCBs left. PCB, EPROM, 9346 EEPROM, 74HC­4053, Labels & Disk $25. P&P $5. Tantau Australia, PO Box 1232, Lane Cove 2066. AH (02) 878 4715. 68HC705 DEVELOPMENT SYSTEM: Editor, assembler, In Circuit Simula­tor and Programmer board. Oztechnics, PO Box 38, Illawong, NSW 2234. Phone (02) 541 0310. Fax (02) 541 0734. email:OZTEC<at>OZE­MAIL.COM.AU. YOUR UNUSUAL PARTS source: UCN5804B, DS1620, DS1202, DS­ 2401, DS1215, DS1232, UGN3503U, UDN2998W, UDN2993B, MAX038, MAX691, ISD2590, IR LEDs, PCB mounted switches, latest remote control decoder chip & more. With data sheets. DIY Electronics, tel/fax: (058) 62 1915. 486 DX4 100MHz AMD CPU on a VLB motherboard with 256 cache. $475 plus 5% S/H. Prices are in Canadian dol- MEMORY * DRIVES * MODEMS LASER PRINTER MEMORY HP 2MB UPGRADE $160 CO-PROCESSORS 80387SX/DX to 40MHz $90 SIMMS (Parity/No Parity) COMPAQ 4MB 30 PIN-70 $212 $212 8MB CONTURA $550 4MB 72 PIN-70 $221 $201 TOSHIBA 8MB 72 PIN-70 $477 $416 2100/50 8MB $568 16MB 72 PIN-70 $868 $750 DRIVES SEAGATE 32MB 72 PIN-70 $1713 $1500 545MB EIDE 14ms 3yr $269 EDO SIMMS 850MB EIDE 11ms 3yr $330 4MB (1Mbx32)-70ns $289 1052MB EIDE 12ms 3yr $372 8MB (2Mbx32)-70ns $577 2150MB SCSI 9ms 5yr $1270 MAC MODEMS (Includes Sales Tax) 8MB P’BOOK $450 14,400 BANKSIA 5yr W $283 VIDEO MEMORY 14,400 SPIRIT 2yr W $280 256KX16 70ns (SOJ) $38 28,800 BANKSIA V.FC $366 256KX16 70ns (ZIP) $58 28,800 SPIRIT V.34/V.FC $460 Authorised VIKING COMPONENTS agents. America’s fastest growing computer memory manufacturer. EX TAX PRICING AS AT SEPTEMBER ‘95 Sales Tax 22%, O/Night Delivery $8. Ring For Latest Prices. Credit Cards Welcome. We Also Buy And Trade-In Memory. SPECIAL! (Incl Tax) 1Mbx9 – 70ns Simm $65 1Mbx9 – 80ns Simm $58 PELHAM Ph: (02) 980 6988 Fax: (02) 980 6991 Suite 6, 2 Hillcrest Rd, Pennant Hills, 2120. Basic Stamp 1 & Now 2 HERE AT LAST: Stamp One’s BIG sibling. 16 I/O plus improved instruction set. MicroZed Computers PO Box 634 (296 Cook’s Rd), ARMIDALE 2350 V (067) 722 777 F (067) 728 987 Credit cards accepted. We have other PIC chips with interpreter ‘Counterfeit’ Dev. Kit 8 I/O (Scott Edwards’ low-cost Stamp compatible) FBASIC TICkit 21 I/O lars. Other items are available. Please write for details. Send Money Orders to Renato Zannese, 615 Roding Street, Downsview, Ontario, Canada M3M 2A6. COMPLETE WORKSHOP PROGRAM: suit IBM compatible 386 or better computer. Handles: Stock Control, Customer Records, Debits, Credits, Faults, Manuals and Phone Directory. For demo disk, ring Jack Albers Electronics & Software Development on (045) 71 1640. SWAPMEET: Glenroy 22 Oct. Sites 25/26. Vintage, amateur compon­ents, valves. Catalogue SAE T. Mitchell, 68 Rowan Street, Bendigo 3550. MICROCRAFT PRESENTS: Dunfield (DDS) products are now available in (Versa Tech) Range of accessories stocked. Phone support for all products. Send 2 x 45c postage stamps for information. Australia. Micro C, the affordable “C” compiler for embedded applications. Versions for 8051/52, 8086, 8096, 68HC08, 6809, 68HC11 or 68HC16 $149.95 each + $3 p&h • Now on special is the SDK, a package of ALL the DDS “C” compilers for $410 + $6 p&h (save $139) • EMILY52 is a PC based 8051/52 high speed simulator $69.95 + $3 p&h •DDS demo disks $7 + $3 p&h • VHS VIDEO from the USA (PAL) “CNC X-Y-Z using car alter­nators” (uses alternators as cheap power stepper motors!) $49.95 + $6 p&h (includes SILICON CHIP FLOPPY INDEX WITH FILE VIEWER Now available: the complete index to all SILICON CHIP articles since the first issue in November 1987. The Floppy Index comes with a handy file viewer that lets you look at the index line by line or page by page for quick browsing, or you can use the search function. All commands are listed on the screen, so you’ll always know what to do next. Notes & Errata also now available: this file lets you quickly check out the Notes & Errata (if any) for all articles published in SILICON CHIP. Not an index but a complete copy of all Notes & Errata text (diagrams not included). The file viewer is included in the price, so that you can quickly locate the item of interest. The Floppy Index and Notes & Errata files are supplied in ASCII format on a 3.5-inch or 5.25-inch floppy disc to suit PC-compatible computers. Note: the File Viewer requires MSDOS 3.3 or above. Price $7.00 each + $3 p&p. Send your order to: Silicon Chip Publications, PO Box 139, Collaroy 2097; or phone (02) 9979 5644 & quote your credit card number; or fax the details to (02) 9979 6503. Please specify 3.5-inch or 5.25-inch disc. October 1995  95 Microprocessor For Digital Effects Unit Microprocessor For Stereo Preamplifier Advertising Index Now available: the 68HC705-C8P pre-programmed micro­pro­cessor IC for the Digital Effects Unit described in the Feb­ruary 1995 issue. Price: $45 + $6 p+p Payment by cheque, money order or credit card to: Silicon Chip Pub­lica­ tions, PO Box 139, Collaroy, NSW 2097. Phone (02) 9979 5644; Fax (02) 9979 6503. Available now: the 68HC705-C8P pre-programmed micro­pro­cessor for the Remote Controlled Stereo Preamplifier (Sept.-Oct. 1993). Price: $45 + $6 p+p Payment by cheque, money order or credit card to: Silicon Chip Pub­ lications, PO Box 139, Collaroy, NSW 2097. Phone (02) 9979 5644; Fax (02) 9979 6503. Altronics ................................ 28-30 diagrams) • Device programming EPROMs/PALs etc from $1.50 (inc label). We use and recommend the HILO ALL-07 Universal Programmer • Fixed price PCB layout & photoplots. We use and recommend PROTEL For Windows EDA tools • Credit cards accepted • Call Bob for more de­tails. MICROCRAFT, PO Box 514, Concord, NSW 2137. Phone (02) 744 5440 or Fax (02) 744 9280. C COMPILERS: Dunfield compilers are now even better value. Everything you need to develop C and ASM software for 68HC08, 6809, 68HC11, 68HC16, 8051/52, 8080/85, 8086 or 8096: $140.00 each. Macro Cross Assemblers for these CPUs + 6800/01/03/05 and 6502: $140 for the set. Debug monitors: $70 for 6 CPUs. All compilers, XASMs and monitors: $400. 8051/52 or 80C320 simulator (fast): $70. Demo disk: FREE. All prices + $5 p&p. GRANTRONICS PTY LTD, PO Box 275, Wentworth­ville 2145. Ph/Fax (02) 631 1236. PROGRAMMER/EDITOR SOFTWARE for new Lattice EEPROM 7ns Generic Digital Switch ICs. Just connect to PC parallel port! Use to reconfigure circuits without rewiring! Send SSAE, phone or Av-Comm.....................................79 Avico Electronics.........................85 Car Projects Book......................IFC Dick Smith Electronics........... 12-15 Emona.........................................83 Harbuch Electronics....................85 Instant PCBs................................96 IRT Electronics..............................9 Jaycar ................................... 45-52 poll fax. Advanced R & D Solutions, 12 Copeland Road, Lethbridge Park 2770. Ph/Fax (02) 628 1223. NEW SPRINKLER CONTROLLER KITS: RAIN BRAIN version uses ‘C8 and switch mode supply. Features galore!! Contact Mantis Micro Pro­ducts, 38 Garnet St, Niddrie 3042. Phone/fax (03) 337 1917. SATELLITE DISHES: international reception of Intelsat, Panamsat, Gorizont, Rimsat. Warehouse Sale – 4.6m Dish & Pole $1499; LNB $50; Feed $75. All accessories available. Videosat, 2/28 Salisbury Rd, Hornsby. Phone (02) 482 3100 8.30-5.00 M-F. WANTED SERVICE MANUAL or copy (including schematics) and probes for Gould/ Bidmatton K450 logic analyser. After 7:00pm (03) 872 3360. Kalex............................................43 Macservice...............................3,81 MicroZed Computers...................95 Oatley Electronics.................. 64-65 Pelham........................................95 Railway Projects Book.............OBC RCS Radio ..................................94 Rod Irving Electronics .......... 69-73 R.S.K. Electronics........................85 Scan Audio..................................84 Silicon Chip Back Issues....... 90-91 Silicon Chip Bookshop.................53 Silicon Chip Walchart................IBC Spectrum Management Agency....9 SILICON CHIP BINDERS These binders will protect your copies of SILICON CHIP. ★ Heavy board covers with 2-tone green vinyl covering ★ Each binder holds up to 14 issues ★ SILICON CHIP logo printed in gold-coloured lettering on spine & cover Price: $A14.95 each (incl. postage in Aust). NZ & PNG orders please add $A5 each for p&p. To order, just fill in & mail the order form in this issue to: Silicon Chip Publications, PO Box 139, Collaroy 2097; Or phone (02) 9979 5644 & quote your credit card details or fax (02) 9979 6503. 96  Silicon Chip Tortech.........................................43 _________________________________ 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. • Marday Services, PO Box 19-189, Avondale, Auckland, NZ. Phone (09) 828 5730.