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SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings.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 Vol.7, No.6; June 1994 FEATURES FEATURES   4 News: Nissan’s Future Electric Vehicle by Julian Edgar THIS RUGGED AMPLIFIER module will deliver 200W RMS into 8-ohm loads & 350W RMS into 4-ohm loads. Find out how to build it by turning to page 14. Interesting new design uses a fast-charge battery   6 Electronic Engine Management, Pt.9 by Julian Edgar Fault diagnosis & codes 11 Moving Map Display For Helicopters It uses data from the GPS satellites 29 The Emporer’s New Clothes by Kris McLean The sales hype about technology 69 Review: Visual Basic 3.0 – The New Standard? by Darren Yates The easy way to Windows programmimg PROJECTS PROJECTS TO TO BUILD BUILD 14 200W/350W Mosfet Amplifier Module by Anthony Holton HERE’S A PROJECT THAT could prevent serious damage to your car’s engine. It will warn you instantly if a radiator hose bursts & the water level in your radiator drops – see page 20. Rugged design delivers 200W into 8-ohms or 350W into 4-ohms 20 A Coolant Level Alarm For Your Car by John Clarke It could prevent serious engine damage 30 An 80-Metre AM/CW Transmitter For Amateurs by Darren Yates Easy-to-build unit is deal for novice & QRP operators 36 The Stoney Broke Loudspeaker System by Leo Simpson Low-cost compact speakers for the bedroom 54 Convert Your Phono Inputs To Line Inputs by Leo Simpson This simple passive circuit does the job 62 A PC-Based Nicad Battery Monitor by Darren Yates It plugs into your PC’s games port SPECIAL SPECIAL COLUMNS COLUMNS YOU DON’T NEED lots of money to get started on the 3.5MHz amateur band. This low-cost transmitter is easy to build, puts out about 100mW PEP & is ideal for use by novice & QRP operators alike. Details page 30. 40 Serviceman’s Log by the TV Serviceman Around the world for sixpence 66 Computer Bits by Darren Yates BIOS interrupts: your computer’s nuts & bolts 72 Remote Control by Bob Young Servicing batteries & chargers 80 Vintage Radio by John Hill Timber cabinets, antique dealers & vintage radio prices 84 Amateur Radio by Garry Cratt Review: Kenwood’s TS50S HF transceiver DEPARTMENTS DEPARTMENTS   2   3 53 58 86 Publisher’s Letter Mailbag Order Form Circuit Notebook Back Issues 88 91 93 94 96 Product Showcase Ask Silicon Chip Notes & Errata Market Centre Advertising Index LOOKING FOR a pair of compact loudspeakers that are cheap but still sound OK? If that’s the case, then try the Stoney Broke loudspeaker system. They cost just $89.95 for the pair & are a cinch to build – see page 36. Cover concept: Marque Crozman June 1994  1 Publisher & Editor-in-Chief Leo Simpson, B.Bus. Editor Greg Swain, B.Sc.(Hons.) Technical Staff John Clarke, B.E.(Elec.) Robert Flynn Darren Yates, B.Sc. Reader Services Ann Jenkinson Sharon Macdonald Advertising Enquiries Leo Simpson Phone (02) 979 5644 Mobile phone (018) 28 5532 Regular Contributors Brendan Akhurst Garry Cratt, VK2YBX Marque Crozman, VK2ZLZ John Hill Jim Lawler, MTETIA Bryan Maher, M.E., B.Sc. 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) 979 5644. Fax (02) 979 6503. PUBLISHER'S LETTER Most security lighting is a waste of electricity Someone has to say it: most security lighting is a waste. It doesn’t stop burglaries and it wastes electricity. Anyone who drives or walks around the cities and suburbs at night must be aware of a huge farce: the booming growth of security lighting. Homes and factories are sprouting these lights which stay on for most of the night. Now what is the point of security lighting? It is supposed to stop burglaries isn’t it? Well, anyone who cares to look can see that most security lighting, particularly that around homes, would actually help rather than hinder a burglar. For a start, many people use their outside lighting when they are not at home. So straight away the potential burglar has a beacon to guide him to a likely prospect. Second, the lighting is usually aimed from the house out to the street and like as not, straight into the eyes of the neighbours. So the neighbours are dazzled if they actually do look across the street and could not see anybody breaking in. If security lighting was designed to enable burglars to be seen, it would be aimed at the house in question and project no glare at the likely observer. Nor would there be any deep shadows to provide cover for the burglar. That is almost impossible to achieve unless many lights are used and there is no shrubbery at all between the house and street. But the fact is that many, if not most, house break-ins occur during the day. Does this mean that security lighting is so effective that burglars now only work during the day? I hardly think so. But even if security lighting was shown to stop burglaries at night, you still have to ask, “Why have it on during all hours of darkness?” Not only does it waste electricity but it is incon­siderate to the neighbours who must now sleep with curtains drawn and so on. If you take a typical home security lighting setup, there will be a minimum of 300 watts of lighting and it will operate at least eight hours a night, every night of the year. On current Sydney Electricity domestic rates at 10.25 cents per kilowatt-hour, that will cost a minimum of $89 per annum. Yet by including a PIR (passive infrared) sensor to turn on the lights only when they are needed, that bill could be reduced to almost zero and cut out all the light pollution too. If you must have security lighting, the use of PIR sensors at least adds to the element of surprise to a burglar making an attempt on your prop­erty. In fact, just recently I had occasion to talk to an in­surance assessor about the best measures to reduce the possibili­ty of burglary. I asked him about such things as dial-back-to-base burglar alarms, security lighting (all of which our commer­cial premises have) and so on. His answer was simple: ensure you have good perimeter security (ie, locks on windows and doors). There is little else you can do against someone who is determined to be a thief. 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 MAILBAG Audio dropouts in cassette decks I seek your readers’ assistance to verify my facts regard­ing tape cassettes. Some years ago, a reader of another electronics magazine wrote to the editor complaining about the high level of audio dropouts on compact cassette. The editor was quick to suggest about a dozen possibilities for faults in the reader’s deck but, having worked in the broadcast industry and observed the same symptoms myself with top of the range decks, I thought there was more to the story than to dismiss the problem as being faulty hardware. Up until recently, I have been unable to locate the source of these mysterious dropouts, until having a massive run-in with a Japanese deck and media organisation who refused, even when shown the defect in their tapes, to acknowledge the problem. The defect is readily found by taking a brand new tape out of the wrapper and fast forwarding it to the other end. If you record tone on the tape you can hear the audio dropouts and, at the place where the dropout occurs, you will find a small lateral crease in the tape. You can see it quite easily by reflecting light on the media and using a biro to spool the tape through. Usually the effects can be from the first 30 seconds up to 10 minutes into the tape. And if you have a tape which has been played from end to end many times, the problem can then be found at both ends of the tape. I have tested hundreds of top-brand tapes and each has the defect in varying degrees. It does not matter if the tape is a C60 or C90. If any reader knows of a supplier of cassettes with­ out the defect, I would appreciate hearing from them so that I can investigate why. G. Dicker, Kensington, SA. Video switcher for amateur TV I have been a regular reader of your magazine since its inception back in 1987 and have every copy since then. I have responded to your survey, which is enclosed with this letter. My main interest is in amateur radio, with involvement in amateur television. We have at least three ATV repeaters in Adelaide and one repeater in the mid-north of the state (three AM type and one FM type). I would like to see more projects appear in the magazine in relation to ATV. A project idea, for example, is a 6-input video/audio switching unit with preview facilities using interlocking switch­es for main and preview selection. This would allow cameras to be set up and video material previewed before going to air. My original idea was to have a small colour bar generator built into the switcher unit. I wish you luck for the future. D. Sampson, Seaton, SA. Comment: we featured a 3-way video/ audio switcher in the June 1992 issue. This could be extended to provide switching for six video sources but the result would be expensive. Reaction to the proposed change to 230VAC I am writing concerning the Publisher’s Letter in the April 1994 issue concerning the proposed change to 230VAC. A lot of modern electronic equipment will operate satisfactorily over a considerable range of supply voltages. Some other equipment is more costly if it has to be designed to operate at 250 volts and will perform unsatisfactorily at 220 volts. Non-standardisation is a serious problem in certain countries, most notably in Japan. Southern Japan is supplied at 50Hz, while Northern Japan has a 60Hz supply. 110 volt, 220 volt and dual 110/220 volt supplies are found in both areas, although 50Hz areas are normally 220 volts; different plugs are now used but accidents still occur. The same situation occurs in South America, although dif­ferent systems are not normally used in the same country. Europe standardised its SILICON CHIP, PO Box 139, Collaroy, NSW 2097. supply frequency at 50Hz after World War II, although there are still 162/3Hz supplies for railway traction. Many cities still had DC supply at the time, while parts of Spain used 60Hz. However, there are still 110 volt supplies in some parts of Europe, especially in Italy and Spain: These supplies are often found in older buildings with a private substation. Non standardisation of electrical voltage can create prob­lems for travellers and people migrating, as their existing appliances will not work, and must be replaced, often at consid­ erable cost. Such costs could inhibit movement and thus have undesirable economic consequences. A. Dunne, Melbourne, Vic. Reduced voltage will cause problems I would like to respond to your April editorial on the proposal to reduce Australian mains voltage to 230 volts. I wonder if the people behind this idea have sat down with a large Variac and checked out the effect on equipment in the real world. Not every one has 240VAC at their switchboard, especially in rural areas or in our faster growing suburbs, and as someone who commenced employment in the electrical industry 50 years ago, I have seen plenty of occasions where even a short term drop in mains voltage has caused problems with such items as air compres­sors, refrigerators and heating appliances, as well as power tools, especially on building sites where long extension leads are in use. Other problems would be lighting levels and colour tempera­ture in film and photographic studios, without expensive “re-lamping”. Other voltage critical equipment would be x-ray installations and older medical gear. One could go on and on with potential prob­ lems but a few moment’s thought could come up with plenty of examples. Norman J. Marks, Pennant Hills, NSW. June 1994  3 Automotive Electronics Nissan’s Future Electric Vehicle As car manufacturers prepare for coming Californian legis­ lation requiring the availability for sale of zero emissions vehicles, the trickle of electric cars is becoming a deluge. All still lack the fundamental requirement which would enable elec­ tric cars to really take off – a compact and lightweight battery – but the use of conventional battery materials is advancing slowly. Nissan’s Future Electric Vehicle (FEV) uses a nickel-cadmi­um battery pack. This battery has advantages over conventional lead-acid batteries in terms of power density (200-240Wh/ kg versus 130Wh/kg for lead-acid). In addition, the battery pack can also be partially recharged in a very short time. Nissan claims that the battery can be recharged to 40% capacity in as little as six minutes – comparable to the refill time of a petrol-powered vehicle. The battery, which has a mass of 200kg, is cooled by air circulation. The need for cooling has been lessened by a reduc­tion in the battery’s internal resistance and the reaction heat generated during charging. Stop/start engine for VW Golf Ecomatic 4  Silicon Chip Four different battery charging systems are utilised; (1) slow recharging overnight using the charger in the car; (2) recharging using the super-quick battery charger previously mentioned; (3) recharging from a roof-mounted solar panel; and (4) recharging via a regenerative braking system. The last two methods are essentially used to ‘top-up’ the battery. The storage battery generates an output of 280V and drives two high-speed (15,000rpm) 20kW 4-pole AC motors via a 10kHz inverter which uses Insulated Gate Bipolar Transistors (IGBTs). The drive reduction is through a 1:12 ratio planetary gear train. The bodywork of the car features an aluminium frame to reduce mass (although Nissan does not quote a kerb weight), while the aerodynamic drag (Cd) has been reduced to just 0.19. This Cd figure is extremely low for a passenger car. The vehicle’s accel­ eration, top speed, range and cost have not been released by Nissan, suggesting that a production electric car utilising this technology is still some way from reality. While the automotive world continues to await a break­through in the energy density of rechargeable batteries, Volkswa­gen has recently released an urban car which makes the most of conventional design elements. Featuring a diesel engine, the Ecomatic Golf compact car achieves excellent fuel economy and very low pollution emissions by having the engine off for up to 60% of the time during city driving. When the accelerator pedal is released under certain condi­tions, the engine is stopped and a vacuum servo clutch disen­ gages, allowing the car to free-wheel. An electronic module, which includes inputs for engine coolant temperature and road speed, is used to switch the engine on and off. If either the gearstick is moved or the throttle is de­pressed, the engine restarts. Ancillaries such as power steering and brakes – which are normally operated by engine-driven devices – are maintained when the engine is not running by a battery pack and electric motors. The car is driven as if it has a manual transmission but without the clutch. Because so much city driving is of the stop-start type (especially in Europe), the engine is off for up to 60% of the time. During this period, zero emissions are generated and the fuel normally consumed by the idling engine is saved. The urban fuel consumption of the car is just 4.6 litres/100km (60mpg). Carbon dioxide, hydrocarbon and oxides of nitrogen emissions are down by about 22% and carbon monoxide emissions are reduced by 36% compared to a conventional model. There are no plans at this stage to sell the car in Austra­lia. SATELLITE SUPPLIES Aussat systems from under $850 SATELLITE RECEIVERS FROM .$280 LNB’s Ku FROM ..............................$229 LNB’s C FROM .................................$330 FEEDHORNS Ku BAND FROM ......$45 FEEDHORNS C.BAND FROM .........$95 Electronics & Holden’s VR Commodore DISHES 60m to 3.7m FROM ...........$130 LOTS OF OTHER ITEMS FROM COAXIAL CABLE, DECODERS, ANGLE METERS, IN-LINE COAX AMPS, PAY-TV DECODER FOR JAPANESE, NTSC TO PAL TRANSCODERS, E-PAL DECODERS, PLUS MANY MORE For a free catalogue, fill in & mail or fax this coupon. ✍ If anyone doubts the direction in which car design is heading, particularly as it relates to electronics, then this photo from Holden should dispel them. It shows Holden engineer Gary Carroll with nine electronic control modules which are used as standard equipment in the top-of-the range VR Commodore Calais. These electronic modules are used in the engine management system, automatic transmission, anti-lock braking system, airbag deployment, trip computer and body computer, the latter looking after the operation of the interior lights, headlights and so on. In addition, there are electronic keys to switch the alarm on and off and to control the central locking system.     Please send me a free catalog on your satellite systems. Name:____________________________ Street:____________________________ Suburb:_________________________ P/code________Phone_____________ L&M Satellite Supplies 33-35 Wickham Rd, Moorabin 3189 Ph (03) 553 1763; Fax (03) 532 2957 June 1994  5 Electronic Engine Management Pt.9: Fault Diagnosis – by Julian Edgar Electronic engine management systems rarely fail. In 10 years of driving five different EFI cars – including highly modified examples – I have been stranded on the roadside only once. The reason for that unscheduled stop was that the main EFI relay had corrosion on its pins where it plugged SENSORS SENSOR 1 into the wiring loom socket – it was as simple as that. As with most purely electronic devices, the ECM itself is likely to last for many years without internal failure – unless an output is short circuit­ed or it suffers physical damage. Problems which crop up in engine-managed cars CONNECTORS CONNECTORS ACTUATORS ACTUATOR 1 ELECTRONIC CONTROL UNIT SENSOR 2 ACTUATOR 2 30% 15% 30% 15% 10% Fig.1: most faults in engine management systems occur outside the electronic control module. It’s therefore usually wrong to initially assume that the fault lies within the ECM. TABLE 1: LIMP-HOME OPERATIONS Sensor Failure Diagnosis Method Fail-Safe Operation Water temperature Abnormal voltage Radiator fan kept switched on; specific water temperature value substituted Knock sensor Abnormal voltage Regular fuel map set; ignition timing retarded by 5° Turbo control Faulty sensor or pressure valve Fuel cut-off under full throttle & heavy load Airflow sensor Abnormal voltage Fuel injection controlled by rpm & throttle opening 6  Silicon Chip tend to be in the electrical/mechanical interfaces – the input sensors and the output devices. Fig.1 shows that 90% of the faults are caused by connector, sensor or actuator faults. But how do you find the problem? The first aspect to establish with absolute certainty is that it actually is the engine management system which is at fault. Poor fuel economy might be caused by a faulty injector, or it might be the brakes dragging. Or the engine might be hard to start because the hose to the MAP sensor is blocked; or it might be because there’s water in the fuel! There is a tendency – especially among people familiar with electronics but less used to mechanics – to start with the most complicated possible explanation first. However, all logical mechanical alternatives to engine management problems should be carefully examined first before turning to the elec­tronics. Limp-home operations All modern engine-managed cars run self-diagnostic facilities, where the ECM can be instructed to check for any fault codes held in its memory. It may be that an intermittent wiring problem exists with a sensor where, for example, the ECM loses its knock sensor input over large road bumps. Or a sensor may be returning a signal to the ECM which is well out of nor- If there’s a problem, where do you start? Most engine-managed cars have a built-in self diagnosis system to make fault finding much easier. This is a Daihatsu Mira Turbo engine. mal parame­ters and so the ECM may be using an internally-programmed limp-home replacement signal for that particular sensor. In both cases, the fault code for the circuit will be retained within the ECM’s memory. To indicate that an ECM problem exists, most cars illu­minate a “check engine” light on the dashboard. Some cars will show the light only briefly and then, if the fault is not major, douse the light so as not to cause driver concern. At the car’s next service, the fault codes can be accessed as a normal part of the procedure and the problem found and remedied. The fault code is then manually cleared from the memory. However, there are many cars which don’t run dash-mounted engine management warning lights. If your car is one of these, there are two possibilities: (1) your car’s engine management system doesn’t have self-diagnosis facilities; or (2) self-diagnosis is used but there is no indication on the dashboard when fault codes are logged. It is this last situation which prompted 1 CHECK EACH FUEL INJECTOR FOR OPERATION OK CHECK FUEL PRESSURE NOT OK 2 CHECK VOLTAGE AT FUEL INJECTOR'S POWER TERMINAL NOT OK REPAIR HARNESS/CONNECTOR OK 3 CHECK FUEL INJECTORS NOT OK REPLACE FUEL INJECTOR OK 4 CHECK VOLTAGE AT EACH ECU TERMINAL NOT OK REPAIR HARNESS/CONNECTOR OK 5 CHECK HARNESS CONNECTORS BETWEEN ECU AND BODY NOT OK REPAIR HARNESS/CONNECTOR OK REPAIR ECU TERMINAL POOR CONTACT (REPLACE ECU) Fig.2: many factory workshop manuals provide flow charts for fault diagnosis; eg, if the engine won’t start. This particular flow chart is for the Subaru Liberty & shows the procedure to follow when checking the fuel injection system. June 1994  7 at least one mechanic to suggest that there are probably thousands of cars being driven around in constant limphome mode, their owners probably complaining that EFI cars use too much fuel, don’t start well, or have a poor idle! In fact, many limp-home or fail-safe operations are engi­neered so well that the driver will not notice any change in engine performance. Table 1 shows some of the limp-home capabili­ties of a Subaru Liberty RS Turbo. Accessing self-diagnostics DIAGNOSTIC MODE SELECTOR LIGHT-EMITTING DIODES Fig.3: self-diagnosis is triggered in different ways in different cars. In this Nissan system, coloured LEDs flash codes through an opening in the ECM case after the pot has been rotated to the correct position. Self-diagnosis in the Daihatsu Mira is activated by shorting two of the terminals in the under-bonnet diagnostic plug. This causes the “check engine” light to flash a coded output. 8  Silicon Chip The procedure undertaken to trigger the self-diagno­sis mode depends on the make of the car. In order to use the self-diagnosis mode, read the fault codes and carry out proper fault-finding, you need to have access to a workshop manual. These days, major new models are released with very extensive workshop manuals. The Subaru Liberty, for example, has a factory workshop manual comprising six volumes, with the engine management book alone being over 400 pages long! However, such manuals are expensive and often the manufac­turer will not sell them directly to the public. However, TAFE colleges which teach automotive subjects often have factory workshop manuals in their libraries, START ENGINE Protect your valuable issues Silicon Chip Binders WARM-UP ENGINE TURN IGNITION SWITCH OFF CONNECT TEST MODE CONNECTOR TURN IGNITION SWITCH ON (ENGINE OFF) CHECK I F CHECK ENGINE LI GHTS T UR N ON NO INSPECT CONTROL UNIT POWER SUPPLY AND GROU ND LI NE AN D CHECK ENGINE L IGHT LI NE DEPRESS ACCELERATOR PEDAL COMPLETELY. THEN RETURN IT TO THE HALF THROTTLE POSITION AND HOLD IT THERE FOR TWO SECONDS. RELEASE PEDAL COMPLETELY. START ENGINE These beautifully-made binders will protect your copies of SILICON CHIP. They feature heavy-board covers & are made from a dis­ tinctive 2-tone green vinyl. They hold up to 14 issues & will look great on your bookshelf. ★ High quality ★ Hold up to 14 issues YES CHECK I F CHECK ENGINE LI GHT I NDICA TES TROUBLE CODE ★ 80mm internal width ★ SILICON CHIP logo printed in gold-coloured lettering on spine & cover DRIVE AT SPEED GREATER THAN 11km/h FOR AT LEAST ONE MINUTE AND SHIFT UP TO 4th SPEED Price: $A14.95 (includes postage in Australia). NZ & PNG orders please add $A5 each for postage. Not available elsewhere. NO WARM-UP ENGINE ABOVE 2000RPM CHECK I F CHECK ENGINE LIGHT BLINKS YES TURN IGNITION SWITCH OFF Or fax (02) 979 6503; or ring (02) 979 5644 & quote your credit card number. NO NO CHECK I F CHECK ENGINE L IGHT I NDICA T ES TROUBLE CODE DISCONNECT TEST MODE CONNECTOR CONFIRM TROUBLE CODE SELF-DIAGNOSIS SYSTEMS ARE OK. TROUBLE IS IN SOME OTHER SYSTEM Use this handy form ➦ YES Enclosed is my cheque/money order for $________ or please debit my MAKE SEQUENTIAL CHECKS OF TROUBLE CODE ❏ Bankcard   ❏ Visa   ❏ Mastercard Fig.4: this flow chart shows the self-diagnosis procedure for the Subaru Liberty. which are open to the pub­lic, while the Gregorys workshop manuals usually list fault codes and give a brief overview of testing procedures. Because each car is different, the examples used here relate specifically to the models being discussed. Most cars are similar but the codes and procedures will vary from car to car. Another initial problem in access- ing the self-diagnosis codes is that manufacturers often don’t give direct instructions on how to trigger the system’s operation. In one Daihatsu work­ shop manual for example, the listed procedure is to plug the under-bonnet check connector into Special Service Tool number 09991-87201-000. In fact, all this grand “tool” does is short the ECM self-diagnosis trigger wire Card No: ______________________________ Card Expiry Date ____/____ Signature ________________________ Name ___________________________ Address__________________________ __________________ P/code_______ June 1994  9 0.5s TABLE 2 Flashes GLOWING EXTINGUISHED 4.5s 0.5s MALFUNCTION CODE 3 Fig.5: this chart shows how the “check engine” light flashes the diagnostic codes in the Daihatsu Mira. Faulty Circuit 2 MAP sensor 3 Ignition signal 4 Water temp sensor 5 Oxygen sensor 6 Engine rpm sensor 9 Vehicle speed sensor 11 Airconditioner switch TABLE 3 to ground! A bent paper clip used to connect two of the check socket’s terminals together does exactly the same job. A close examination of the workshop manu­al or a chat with a friendly mechanic at the local dealership will usually reveal all. Reading the codes If the car doesn’t have a “check-engine” light but still uses a self-diagnosis system, then LEDs mounted MALFUNCTION DISPLAY 01 02 03 04 05 OUTPUT SIGNAL (SELF-DIAGNOSIS CHECKER) ON OFF ON OFF ON OFF ON OFF ON OFF 10  Silicon Chip Possible Causes Engine difficult/fails to start 1, 2, 3, 4, 5, 7, 8, 9, 11, 12 Engine starts, then stalls 1, 2, 3, 4, 8, 9, 11, 12, 13 Acceleration flat spot 1, 4, 6, 8, 14 Engine surge 1, 4, 5, 6, 7, 8, 9, 11 Variable idle speed 4, 6, 10, 11, 12, 13 Engine misses 1, 2, 5, 7, 8, 12, 15 Lack of power 1, 4, 6, 7, 8, 9, 13, 14, 15 High fuel consumption 1, 4, 5, 7, 8, 9, 13 1 = ignition module; 2 = control relay; 3 = fuel pump; 4 = airflow meter; 5 = ECM; 6 = air intake system (leaks); 7 = injectors; 8 = fuel pressure; 9 = coolant temp sensor; 10 = throttle valve; 11 = idle air bypass valve; 12 = loom, earth points; 13 = throttle position switch; 14 = air filter; 15 = fuel filter. Limp-home modes will allow the engine to run near-normally, even with the coolant temperature sensor wire removed from the sensor as has been done here. MALFUNCTION CODE Symptom in the ECM and visible through a small window are usually used as the communica­tion interface. On the other hand, cars with a “check engine” light usually flash this dash-mounted light to communicate the codes. As an example, the Daihatsu system flashes its check engine light at 1Hz, with a 0.5 second duty cycle. Two flashes indicates the digit ‘2’ for example, with a 2.5 second delay until the next fault code is flashed. When all the fault codes have been flashed, there is a 4.5-second delay and then the fault codes present are repeated. If no faults exist, then the light will SENSOR OR SUBSYSTEM SELF-DIAGNOSIS IGNITION PULSE NO IGNITION SIGNAL NE SIGNAL NO NE SIGNAL FROM CRANK ANGLE SENSOR G1 SIGNAL NO G1 SIGNAL G2 SIGNAL NO G2 SIGNAL KNOCK SENSOR AND KNOCK CONTROL UNIT OPEN OR SHORT CIRCUIT flash ‘1’ at 4.5-second intervals. Table 2 shows the other fault codes. Note that it is the circuit which is faulty and not neces­sarily the sensor itself. Any wiring loom problems obviously also have to be checked. Older ECM systems Finally, what if your car is one which doesn’t run any form of self-diagnosis? These are more likely to be older cars and there­fore are more likely to suffer problems because of their age. With these systems, there are really no quick answers, however Table 3 makes SC a good starting point. FAIL-SAFE NEITHER G1 NOR G2 SIGNAL: ENGINE STOPPED RETARDS IGNITION TIMING 6o I N HE AV YLOAD CONDITIONS WASTE GATE OPENS EARLIER Fig.6: part of the selfdiagnosis section in the Mazda MX-6 turbo workshop manual. The malfunction code indicates a problem with that particular circuit, and can include connector, wiring, sensor and ECM faults. Moving map display used in helicopter fire-fighting In January of this year, large areas around Sydney & the NSW coast were devastated by bushfires. Helicopters were used in number of ways during that time &, for some, their task of navigating through smoke-filled skies was made easier & safer by GPS posi­tion data. Most readers would now be familiar with GPS (Global Posi­tioning System) satellite receivers and the revolution that they have brought about in navigation, whether on the high seas, on land or in the air. But helicopter pilots flying above cities don’t want latitude and longitude information - they want to know what street is immediately below them. AusGPS provides this information. AusGPS is an Australian developed software package which converts position data from a Sony GPS (Global Positioning Sys­tem) satellite receiver into a moving map display on the screen of a portable laptop computer. It proved to be of immense benefit to helicopter pilots, their navigators and observers during the NSW bushfires in early January. The need to navigate through thick bushfire smoke to water bomb outbreaks, transport personnel or ignite backburns proved to numerous helicopter pilots that conventional GPS receivers which give a position report in latitude and longitude were com­ para­tively useless. Melbourne-based GPS technology developer, Resource Industry Associates (RIA), developed the Aus GPS software in conjunction with Electro­ com in Sydney, combining the power The AusGPS moving map software running on a laptop computer enabled helicopter pilots & their observers to operate with pinpoint accuracy in conditions of thick bushfire smoke during the NSW bushfires in early January. of a GPS receiver with the versatility of a portable laptop colour computer. RIA’s Jeff Bailey said that, fortunately, there were enough helicopters in the air equipped with GPS systems and the AusGPS software. This was sufficient to prove the value of the technolo­gy as a firefighting management aid. With visibility at less than one kilometre, the AusGPS map display continuously showed the position of the nearest power lines, peaks and other obstructions. Every second, the software calculated the bearing and distance to the nearest available landing zone, in case an emergency landing was required. With a helicopter located over a hotspot or new fire out­break, position reporting was incredibly simple. There was no time to look at a paper map or try and figure out the location. The AusGPS display immediately showed the position as a 6-digit map reference, a topographic map number and even the street directory map number and coordinates. Changing a helicopter’s course for a new location couldn’t be simpler. After receiving a 6-digit map reference over the radio, the navigator needed to press only nine keys and the Aus­GPS automatically showed the heading, distance and esti­mated travelling time. By contrast, helicopters using only a GPS receiver fre­quently became disoriented because they could not use the lati­tude and longitude information to quickly find their position on topographic maps. The AusGPS software runs on a laptop PC with a hard disc and 640Kb of RAM. For fast updates, a 386 laptop with a colour display screen is recommended. For further information on GPS receivers and AusGPS soft­ware, contact Jeff Bailey, Resource Industry Associates, 538 Brunswick St, North Fitzroy, 3068. Phone (03) 482 4945 or SC fax (03) 482 4956. June 1994  11 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 200W/350W Mosfet Amplifier Module Here is a rugged amplifier module which will deliver 200 watts RMS into 8Ω loads and 350 watts RMS into 4Ω loads. It uses eight Toshiba plastic encapsulated Mosfets which are each rated at 200 volts, 12 amps & 150 watts. Design by ANTHONY HOLTON When it comes to making complementary Mosfets suitable for big audio power amplifiers, two Japanese companies, Hitachi and Toshiba, have the game sown up. Many enthusiasts will have had experience with Hitachi TO-3 metal encapsulated Mosfets and their recent plastic TO-3P replacements but these plastic devices from Toshiba are something else and have much higher ratings: VDSS 200V (drain-source voltage), drain current 14  Silicon Chip 12 amps and power dissipation 150 watts. The Toshiba devices used are 2SK1530 for the N-channel devices and 2SJ201 for the P-channel devices. They are physically much larger than then familiar Hitachi plastic devices (eg, 2SK1037 and 2SJ161). Compared with the TO-3P encapsulation which is 15mm wide and 20mm high, the Toshiba TO-247 devices measure 20mm wide and 26mm high, not counting the lead dimensions. A particular advantage of the Toshiba devices is that the drain is connected to the heatsink tab which means that the capacitance between tab and heatsink has no practical effect on the performance (ie, it cannot lead to high frequency instabili­ty). Anthony Holton has come up with a design that delivers the goods in terms of power output and with eight devices employed, it should be rugged and reliable. The basic module is a PC board measuring 200 x 90mm with the eight Mosfets mounted along one edge on an aluminium right-angle bracket. Six 5W wirewound source resistors are mounted under­neath the PC board. If your are going to build this module, you will need a transformer with a power rating of at least 500 watts, together with a substantial rectifier and filter capacitors. These will need to be mounted in a roomy chassis with +70V 4.7k 10k Q4 BC546 C B E Q6 MJE350 4.7k Q5 BC546 C B 10pF B 100  E E C C 10 BP 220  B B 470  C C E E Q13 C B A LED1 ORN Q3 BC546 Q11 470   ZD3 15V 15k ZD4 15V 470  330 0.33 5W 0.33 5W 470  G Q12 S 0.47 10  0.22 18k B 10k E C VIEWED FROM BELOW PLASTIC SIDE ZD1 18V Q1 BD681 B 18k 22k 1W 470  470  470  Q7 MJE340 C 100  B E C E 0.33 5W D G Q14 S 0.33 5W 0.33 5W 0.33 5W 4x2SJ201 D G S G 0.33 5W 0.33 5W Q16 S D G Q18 S D Q9 MJE340 100  100 160VW D 4x 2SK1530 D D S G D S G S G K B 470  Q10 MJE340 E .0012 15k Q17 470  10pF Q15 18pF INPUT F1 5A E ZD2 15V BIAS VR1 10k Q2 BC546 Q8 MJE350 47 160VW F2 5A 100 160VW -70V 47 160VW GDS E C B A K 200W/350W MOSFET AMPLIFIER Fig.1: the circuit is fairly conventional with a differential input amplifier, Q2 & Q3, driving cascode transistors Q4 & Q5. These drive the voltage amplifier which consists of a differen­tial pair Q6 & Q8, loaded by a current mirror, Q7 & Q9. The voltage amplifier, in turn, drives the Mosfet output stages (Q11-Q18). a very substantial heatsink. The overall cost is not likely to leave much change out of $500. After all, this is a big power amplifier we’re talking about and they don’t come cheap. Circuit details Now let’s have a look at the circuit – see Fig.1. The circuit is fairly conventional with a differential input amplifier, Q2 & Q3, driving cascode transistors Q4 & Q5. These drive the voltage amplifier which consists of a differen­tial pair Q6 & Q8, loaded by a current mirror, Q7 and Q9. The voltage amplifier drives the Mosfet output stages which has all devices connected in source-follower mode to give a large current gain. That summarises the circuit but let’s look at it in more detail. The in- put signal is fed in via a 10µF bipolar electroly­tic capacitor. The 10µF capacitor and the associated 15kΩ bias resistor form a high pass filter which sets the -3dB low frequency response to 1Hz. The input signal also passes via a 220Ω resistor and is shunted by a .0012µF capacitor which together form a low-pass filter to limit frequencies above 600kHz. The input differential amplifier is operated in cascode mode, as noted above. NPN transistors Q2 and Q3 are the differen­ tial pair and their collectors drive the emitters of the cascode transistors Q4 and Q5 and these improve the linearity and fre­ quency response of the stage but this is not the main reason for using the cascode connection. Note that the positive supply of the amplifier is +70V, too high for the 65V collector rating of Q2 and Q3 which are BC546 low noise types. The 15V zener diode ZD2 acts as a voltage refer­ence for the cascode transistors Q4 and Q5 and thus their emit­ters sit at around +14.4V, well within the collector rating of Q4 and Q5. Hence, the cascode transistors act to “regulate” the voltage for the differential pair. Because the cascode transistors Q4 & Q5 have their bases tied to a voltage source, they are effectively in “common base” mode. Hence, as already noted, their input signals appear at their emitters and the outputs at the collectors, to drive the following voltage amplifier stage consisting of differential transistors Q6 & Q8. Voltage amplifier stage The emitters of Q2 & Q3 are connected to a current source comprising transistor Q1 and zener diode ZD1. This is the “tail” of the so-called long tailed pair”. Zener diode ZD1 June 1994  15 This photograph shows how the Vbe multiplier transistor (Q10) is mounted on the top of Mosfet Q11 (metal side down). Smear the metal surface of Q10 with heatsink compound before bolting it into position. sets a constant voltage at the base of Q1 which then applies about 17V to its 18kΩ emitter resistor. This sets the current through Q1 at just under 1mA and this is then shared as emitter current by the input transistors Q2 and Q3. The constant current source needs to withstand almost the full 70V of the negative supply rail and this is why a BD681 is specified. It happens to be a Darlington transistor but more importantly, its collector voltage rating is 100V. As noted above, the voltage amplifier stage is another differential stage but with current mirror loading. Q6 & Q8 are the differential transistors and these are loaded by the current mirror, Q7 & Q9. The current mirror is really another form of constant current load. In effect, NPN transistor Q7 is connected as a forward biased diode and this provides a reference voltage to the base of Q9 which then acts as a constant current load for the collector of Q8. The term “current mirror” comes from the current sharing action in the differential pair. If there is any tendency for Q8 to draw more current then the other half of the differential pair, Q6 is forced to draw less current. The smaller collector current then reduces the voltage applied by Q7 to the base of Q9. Q9 is then throttled BR1 MDA3504 A 50V 240VAC +70V 50V N 10000 75VW 0V E CHASSIS 16  Silicon Chip 10000 75VW -70V Fig.2: the suggested power supply circuit for the amplifier module. Note that the rectifier bridge will dissipate a fair amount of power & this should be taken care of by bolting it to the chassis or to a large heatsink. back to restore the original current condi­ tions. The result of using the current mirror connection is a high gain and excellent linearity. Current mirror stages are commonly found in integrated circuit op amps. Mosfet output stages The complementary output stage comprising the eight Mosfets is biased into class AB operation by the Vbe multiplier transis­tor, Q15, together with an orange light emitting diode, LED 1. This is the quiescent current setting and in this amplifier it is 100mA per device or a total of 400mA. In effect, a standard Vbe multiplier has a bias voltage applied by a trimpot (in this case VR1) between its base and emitter and it amplifies this voltage so that the total voltage appearing between its base and collector is the product of Vbe (the base-emitter voltage) and the ratio of the total resistance of the trimpot to the resistance between base and emitter. To give an example of how this works, let’s say that the 10kΩ trimpot was set so that its resistance between the transistor base and emitter was 2kΩ and the resultant Vbe was 0.6V. The total voltage between collec­ tor and emitter would then be (0.6V x 10kΩ/2kΩ) = 3V. The Vbe multiplier transistor is Q11 4.7k 4.7k +70V 10k 47uF F1 0.47 Q5 Q4 Q2 ZD2 .0012 Q9 B C E 22k 1W 0.22 B C E Q1 10  330uF 220  0. 33  0. 33  Q18 470  ZD4 470  LED1 470  A 470  18pF VR1 Q3 470  18k 15k 0. 33  RESI ST ORS MOU NTED ON COPPER SI DE O F B OARD 100  100  Q7 100uF ZD1 18k 10k 0V,SPKR- 47uF -70V 10uF BP F2 GND INPUT Fig.3: the parts layout on the PC board. Note that the Mosfet power transistors (Q11-Q18) must be isolated from the heatsink using silicon impregnated rubber washers & isolating bushes. The 0.33Ω resistors (shown dotted) are mounted on the copper side of the board. Take care with component orientation. attached to the same heat­sink as the output transistors so if they heat up, the Vbe multi­plier’s voltage is automatically reduced to compensate. Hence the quiescent current stays pretty constant and thermal runaway is avoided. This scheme works well for amplifiers with bipolar transistors and is not necessary in those which used Hitachi Mosfets in the past. However, the thermal characteristics of these Toshiba Mosfets is such that quiescent current stabilisa­tion with a Vbe multiplier transistor is necessary. The catch is that the standard Vbe multiplier circuit overcompensates. This means that when the amplifier is delivering lots of power and is getting Q16 0. 33  0. 33  0. 33  10pF ZD3 B C E Q6 Q14 SPKR+ 15k 100uF 470  10pF Q8 B C E 100  Q12 Q10 0. 33  470  470  470  Q13 0. 33  Q15 0. 33  Q17 hot, the Vbe multiplier reduces its voltage to the point that no forward bias is applied to the output stage. In other words, it reverts to pure class B opera­tion when it gets hot and distortion rises to high levels. The cure is to modify the Vbe multiplier so that it applies less compensation. This is achieved by connecting LED 1 into the emitter circuit of Q15. The result is a circuit which still overcompensates to some extent but this affords a higher degree of thermal stability and prevents damage to the amplifier. Overdrive protection 15V 1W zener diodes ZD3 & ZD4 are connected between the commoned gate and source connections of the complementary Mos­ fets. They are included to prevent the occurrence of gross gate drive which could result if the output of the amplifier was shorted. The zener diodes prevent gate damage but do not provide any protection against excessive current in the output stage; that is provided by the fuses in the positive and negative supply lines. Note that 470Ω resistors are connected in series with the gates of each Mosfet. These provide some limiting of the frequen­cy response and thus reduce the possibility of parasitic oscilla­tion. Each Mosfet also has a 0.33Ω source resistor and these provide local degeneration (current feedback) to slightly improve thermal stability and help promote current sharing amongst the output devices. RESISTOR COLOUR CODES ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ No. 1 2 2 2 2 9 1 3 1 8 Value 22kΩ 18kΩ 15kΩ 10kΩ 4.7kΩ 470Ω 220Ω 100Ω 10Ω 0.33Ω 5W 4-Band Code (1%) red red orange brown brown grey orange brown brown green orange brown brown black orange brown yellow violet red brown yellow violet brown brown red red brown brown brown black brown brown brown black black brown not applicable 5-Band Code (1%) red red black red brown brown grey black red brown brown green black red brown brown black black red brown yellow violet black brown brown yellow violet black black brown red red black black brown brown black black black brown brown black black gold brown not applicable June 1994  17 The completed amplifier board should be bolted to a large finned heatsink with a rating of at least 0.5-0.7 degrees/watt. Don't skimp on the heatsink, otherwise the amplifier will be unable to deliver its rated power. Three capacitors are included in the circuit to roll off the open loop high frequency gain and hence ensure stability. They are the 10pF capacitors between the bases and collectors of Q6 & Q8 and the 18pF capacitor between the collector of Q9 and the base of Q3. The overall AC voltage gain of the amplifier is set by the 15kΩ and 470Ω feedback resistors connected to the base of Q3. These set the gain to 33 times. The resulting input sensitivity is 1.2V RMS for 200 watts into 8Ω or 1.13V RMS for 350 watts into 4Ω. Power supply To run this module, you will need a big power supply. If you want full power into an 8-ohm load you will require a 300VA transformer with two 50V windings. If you want full power into a 4-ohm load, you will need a 600VA transformer. In prac­tice, the only readily available transformer which is suitable is a 500VA toroid available from Altronics (Cat M-3140). The circuit of a suggested power supply is shown in Fig.2. Note that the rectifier bridge will itself dissipate a fair amount of power and this should be taken care of by bolting it to the chassis or heatsink. The filter capacitors should be a minimum of 10,000µF 75VW but preferably should be a bank of 20,000µF or more, for each supply rail. Don’t skimp on the power supply otherwise you will reduce the available performance. For the purpose of this article we shall assume that you have the power supply and chassis details organised to your satisfaction. Where to buy the kit Assembly This design will be available in kit form from Computer & Electronics Services Pty Ltd who own the copyright on the PC board. The kit in­cludes all parts, the aluminium mounting bracket and the PC board which is made from two ounce copper and is tinned, solder masked and silk screened. Price is $159 plus $8.00 for postage and handling within Australia. Fully built and tested modules are $199.00 plus $8.00 postage and handling. Payment may be made by cheque, money order, Bankcard, Visa­card or Mastercard. Send remittances to Computer & Electronic Services Pty Ltd, 27 Osborne Avenue, Launceston, Tasmania 7250. Phone (003) 34 4218. Fax (003) 31 4328. Before you begin any soldering of the PC board, check the copper pattern thoroughly for any shorts or breaks in the copper tracks. The board for the kits will be supplied with a screened component overlay on the top and a green solder mask underneath. The component wiring diagram for the PC board is shown in Fig.3. You can start by inserting and soldering all the PC stakes, resistors, fuse- 18  Silicon Chip Performance of Prototype Output power......................... 200W into 8 ohms, 350 watts into 4 ohms Frequency response ............. 4Hz to 56kHz at -3dB points Input sensitivity ..................... 1.2V RMS (for 200W into 8 ohms) Harmonic distortion .............. <.07% from 20Hz to 10kHz, typically <.005% Signal to noise ratio ������������� -122dB unweighted (20Hz to 20kHz); -126dB A-weighted Damping factor ..................... >200 (for 8 ohm loads) Stability ................................. unconditional holders, the small capacitors and the multi-turn trimpot in their respective positions. Leave the 5W wire­wound resistors on the copper side of the PC board for the time being – we’ll come to these later on. Next, insert the electrolytic capacitors, then continue by inserting the smaller semiconductors such as the BC546s, MJE340s, MJE350s, BD681, zener diodes and the LED. Do not mount the MJE340 for the Vbe multiplier (Q10) yet as this is mounted on one of the Mosfets. Next mount all of the Mosfets on the aluminium angle brack­et and PC board. The leads of each Mosfet will need to be bent at 90° so that they go through the relevant holes in the PC board. The Mosfets should be mounted using silicon impregnated rubber washers and isolating bushes and secured with M3 bolts and nuts. Do not solder them in at this stage. After mounting the Mosfets on the heatsink bracket and PC board, test with a multimeter to check that they are all isolat­ed. Set the multimeter to a high Ohms range and test for an open circuit between the metal bracket and the drain lead of each device. If a short circuit is detected, unbolt the offending device and check for a misplaced washer or bush or metal burrs around the mounting hole. Once satisfied that there are no shorts on any of the devices, solder the Mosfets in place. The next task is the mount­ing of the Vbe multiplier transistor (Q10). This is mounted on top of Q11 with the metal tab facing down and using the existing mounting bolt. Once it is mounted, trim the leads of Q10 back to about 10mm long and tin them with solder. Cut three lengths of hookup wire (40mm each) and strip and tin wires at both ends. Insert and solder the three wires in the three remaining holes in the PC board, adjacent to trimpot VR1. Solder each wire to the appropriate base, emitter and col­lector leads of Q10. The last task is the mounting of the 5W wirewound source resistors on the copper side of the PC board. Cut each lead on these resistors to a length of 12mm and then bend them down at 90°. This done, bend a small flat hook at the end of each lead and then solder them in the appropriate positions as shown by the compon­ent overlay. Testing The module should be bolted to a large heatsink with a rating of at least 0.5-0.7°/watt. Remove the fuses and solder a 22Ω 5W resistor in their places. These resistors provide a convenient way of setting and measuring the quiescent current and also protect the amplifier in the event that there is a fault. They may go up in smoke but the amplifier will be protect­ed. Measure the resistance (set your multimeter to the Ohms range) between base and collector of Q10. Adjust VR1 so that this resistance is zero. This adjustment ensures that when power is first applied to the module, the output stage is biased off. Make the appropriate supply and ground connections to the power module. Now apply power and check the DC voltage at the output of the amplifier. It should be within ±50mV of 0V. Now connect the multimeter across one of the 22Ω 5W resis­tors on the fuseholders. The DC voltage should be zero. Now adjust trimpot VR1 so that the voltage across the 22Ω resistors is 13.2 volts. This is equivalent to a total quiescent current in the output stage of 400mA or 100mA per device. PARTS LIST 1 PC board 1 aluminium extrusion, 200 x 90mm x 6mm (see text) 1 large heatsink, Jaycar Cat HH8594 or equivalent 2 M205 PC mount fuseholders 2 5A or 10A M205 fuses 1 10kΩ multi-turn trimpot 6 PC stakes Semiconductors 1 BD681 NPN Darlington transistor (Q1) 4 BC546 NPN low noise transistors (Q2, Q3, Q4, Q5) 2 MJE350 PNP power transistors (Q6,Q8) 3 MJE340 NPN power transistors (Q7, Q9, Q10) 4 2SK1530 N-channel Mosfets (Q11, Q13, Q15, Q17) 4 2SJ201 P-channel Mosfets (Q12, Q14, Q16, Q18) 3 15V 1W zener diodes (ZD2, ZD3, ZD4) 1 18V 1W zener diode (ZD1) 1 orange LED (LED1) Capacitors 1 330µF 16VW electrolytic 2 100µF 160VW PC electrolytics 2 47µF 160VW PC electrolytic 1 10µF 50VW bipolar electrolytic 1 0.47µF 100VW MKT polyester 1 .22µF 100VW MKT polyester 1 .0012µF 100VW MKT polyester 1 18pF ceramic 2 10pF ceramic Resistors (0.25W, 1%) 1 22kΩ 1W 9 470Ω 2 18kΩ 1 220Ω 2 15kΩ 3 100Ω 2 10kΩ 1 10Ω 2 4.7kΩ 8 0.33Ω 5W 2 22Ω 5W (for setup & testing) You can check this by measuring the voltage drop across any of the 0.33Ω 5W source resistors mounted on the copper side of the board. This will be 33mV but will vary over a fair range for each device, due to variations in the forward transfer admit­tance. Now remove the 22Ω resistors across the fuseholders and replace the fuses. Use 5A fuses if you are using an 8-ohm load and 10A fuses for a SC 4-ohm load. June 1994  19 This coolant level alarm will warn you if the water level in your radiator drops below a preset level. It could prevent serious damage to your engine & hence avoid a very expensive repair. B Y FAR THE MOST drastic event that can happen to a car with an alloy head is a sudden rupture in the bottom radiator hose. In just a few seconds, most of the radiator coolant can be lost and the engine will seriously overheat. At the same time, you will get no warning from the temperature gauge or dashboard indicator lights. The loss of water can be so sudden that your first ink­ling that something is wrong is that your car suddenly stops – with a seized engine. Don’t laugh; this sort of thing can happen and the repair bill can run into many thousands of dollars. In a less drastic example, you may lose coolant from a leak in the top radiator hose or from the radiator itself. In this situation, you usually get some warning that something is wrong. Either you may see steam coming from under the bonnet, or you may hear the hiss of escaping steam, or the temperature gauge may suddenly rise to abnormal levels. In these cases, the sensible thing to do is to stop and investigate the problem. But what if someone else is driving the car or the situa­tion is such that there are no warning signs? Before you know it, the engine’s alloy head could be seriously damaged while the temperature sensor (in the engine block) is indicat­ ing that nothing is amiss. The result could be that you have to replace the head plus the head gasket. And the bill can easily be the best part of $2000 or even more. Build a coolant level alarm for your car By JOHN CLARKE & LEO SIMPSON 20  Silicon Chip 8 B C E B BUFFER 12 11 IC1c 100k IkHz OSCILLATOR 14 D3 1N4148 E Q1 BD681 C 100k 4 5 0.5Hz OSCILLATOR 2 IC1b 100k 100k COMPARATOR 1M IC1a LM339 10k 100k 100 16VW A TO COOLANT SENSOR GND 100k +4.7V POWER SUPPLY 6.8k 0.1 ZD1 16V 1W ZD2 4.7V 400mW 1k +2.8V 7 6 3 1 100k 100 16VW +11.3V 33  +12V FROM IGNITION COOLANT LEVEL ALARM 10k B 3.3k INDICATOR LAMP 100k .0047 9 8 100k E C VIEWED FROM BELOW 13 10  IC1d 10 10k 100k 10 16VW 1M D2 1N4004 D1 1N4004 Fig.1 (below): the circuit uses comparator stage IC1a to monitor the coolant sensor. When the resistance of the sensor goes high (ie, when the coolant level drops), IC1a's output goes open circuit & oscillator stage IC1b is enabled. This in turn drives Q1 & the indicator lamp, & also gates oscillator stage IC1c on & off. IC1c then drives complementary output pair Q2 & Q3 via buffer stage IC1d. Looking at it in these terms, the small cost of adding a coolant level alarm is good insurance against a hefty repair bill. This Coolant Level Alarm will alert the driver of loss of fluid before damage occurs. By the way, if you have never needed to have the alloy head on your car replaced, you may feel quite blase about it. However, several of the staff on this magazine have had alloy heads on their cars replaced and they all feel quite differently about it now. A bill for around $2000 is not easily forgotten. Some cars have a sensor to monitor the water level in the overflow tank. However, this will not detect loss of water from the radiator due to a leak. So don’t be lulled into a false sense of security if you have a warning light for your overflow tank level. The only satisfactory means to check radiator fluid loss is to directly measure inside the cooling system itself. Our coolant level alarm comprises a simple fluid sensor plus a small amount of circuitry to detect the sensor output and provide the alarm signal. The alarm is a 1kHz tone which is switched on and off once a second, backed up with a with a flash­ing lamp. It’s an alarm you cannot ignore. The coolant sensor is a standard Ford part (part no XF10K889A), intended for this very job. It is designed to screw into an integral nut on the radiator of some upmarket Fords. It is essentially an insulated stainless steel probe in a threaded plastic housing and the sensor is normally immersed in the radia­tor coolant. The alarm circuitry works by detecting the resistance bet­ ween the sensor and engine chassis. When the coolant drops below the sensor, this resistance goes high, causing the alarm to sound. While it is possible to have a special PLASTIC SIDE B E C SPEAKER DRIVER Q3 BC327 Q2 BC337 2.2 E 47  16VW C B 10k 0.1 The coolant sensor is a standard Ford part (part no XF10K889A), intended for this very job. This screws into an integral nut on the radiator in some upmarket Fords but can also be fitted to the top radiator hose via an adaptor kit. June 1994  21 10uF COOLANT SENSOR 2.2uF 0.1 10k 100k 10  0.1 100k Q2 100uF Q3 Fig.2: make sure that all polarised parts are correctly oriented when installing them on the PC board. Note particularly that ZD1 & ZD2 have different values, so be careful not to transpose these two parts. The same goes for transistors Q2 & Q3. nut fitted by a radiator specialist, allowing you to fit the Ford part to your radiator, we have taken an alternative approach. If your car has a crossflow radiator or one with a plastic header tank, it is unlikely that you will want to modify the radiator. Instead, we have adapted a standard temperature gauge fitting which is de­signed to be fitted to the top radiator hose. The Ford coolant sensor is fitted into this temperature gauge adaptor and hence there is no need to modify the radiator or to completely drain it. In practice, we think it makes sense to buy a new top radiator hose as a spare. You can then fit the temperature gauge adaptor into the existing top radiator hose (more on this later) and wire in the alarm. Alarm circuit The circuit for the Coolant Level Alarm is shown in Fig.1. It comprises an LM339 quad comparator plus a SPEAKER GND .0047 100k 100uF 100k ZD1 INDICATOR LAMP 47  100k IC1 LM339 10k +12V D3 10k 1 100k C B D1 ZD2 100k 33  10k 3.3k 100k 1M 100k 1M 6.8k 100k 1k Q1 D2 E few transistors, diodes, capacitors and resistors. The circuit can be divided into a number of sections which are labelled on Fig.1. These are the power supply, the comparator for the coolant sensor, the 0.5Hz and 1kHz oscillators, and the buffer and speaker driver. Power for the circuit comes from the ignition switch of the vehicle. This provides +12V only when the ignition is on. The +12V is filtered with a 33Ω resistor and 0.1µF capacitor and any transient voltages are clipped with a 16V zener diode (ZD1). Diode D1 isolates the supply to provide +11.3V (nominal) for the IC and this is further decoupled with a 100µF capacitor. Diode D2 separately supplies power for the speaker driver circuit. Now let’s talk about IC1a which is really the heart of the circuit. It is wired as a comparator and it detects whether the sensor is covered by coolant or not. Its inverting input (pin 6) is set at +2.8V via a voltage divider network supplied at +4.7V by zener diode ZD2 and a 1kΩ resistor. This +4.7V rail also supplies the coolant sensor via a 100kΩ resistor. When the sensor is immersed in coolant, the voltage at point A is below +2V. Conversely, when the sensor is not immersed by cool­ant, the voltage at point A will eventually rise to about +4.7V once the 100µF capacitor is fully charged. Normally, the sensor will be immersed and so the voltage will be less than +2V. This means that the non-inverting (+) input of IC1a (pin 7) will be below pin 6 and so the output of the comparator (pin 1) will be pulled low; ie, close to 0V. If the radiator coolant now drops so that the sensor re­sistance to chassis is now very high, the voltage across the sensor will begin to rise, as the 100µF capacitor charges up. As the capacitor charges, the voltage on pin 7 will rise above pin 6 and the output at pin 1 will abruptly go high. Actually, what happens is that the internal open collector transistor at the output of IC1a will switch off, allowing the voltage at pin 1 to rise to a RESISTOR COLOUR CODES ❏ No. ❏   2 ❏ 10 ❏   4 ❏   1 ❏   1 ❏   1 ❏   1 ❏   1 ❏   1 22  Silicon Chip Value 1MΩ 100kΩ 10kΩ 6.8kΩ 3.3kΩ 1kΩ 47Ω 33Ω 10Ω 4-Band Code (1%) brown black green brown brown black yellow brown brown black orange brown blue grey red brown orange orange red brown brown black red brown yellow violet black brown orange orange black brown brown black black brown 5-Band Code (1%) brown black black yellow brown brown black black orange brown brown black black red brown blue grey black brown brown orange orange black brown brown brown black black brown brown yellow violet black gold brown orange orange black gold brown brown black black gold brown This close-up view shows how the 30mm loudspeaker is mounted at one end of the case (see parts list). The assembled PC board clips neatly into a standard plastic case. Use PC stakes at the external wiring points & run the leads through one end of the case via a rubber grommet. Power comes from the car's battery via the ignition switch. value determined by the three 100kΩ resistors connected to this point. A 1MΩ resistor between pin 7 and pin 1 of IC1a provides hysteresis. This prevents the circuit from mistriggering and the 100µF capacitor prevents the circuit from triggering if the sensor momentarily becomes uncovered by coolant due to cornering forces or rough roads. Oscillators There are two oscillators in the circuit, one involving IC1b and the other involving IC1c. Normally, IC1b is prevented from oscillating because its pin 5 input is held low by the output of IC1a. However, when an alarm condition occurs, IC1a’s output goes open circuit (ie, the internal output transistor turns off) and pin 5 rises to about +7V, as set by the three 100kΩ resistors. This causes IC1b’s output at pin 2 to go high and so the 10µF capacitor at pin 4 is now charged via the 100kΩ resistor from the pin 2 output until the voltage reaches the upper threshold of pin 5 (about +7V). At this point, IC1b’s output goes low again and discharges the 10µF capacitor to the lower threshold (about +3.7V) of the pin 5 input. This cycle repeats itself and the result is square wave at the output of IC1b which switches low for about one second and then high for one second (ie, IC1b oscillates at a frequency of 0.5Hz). The output of IC1b drives the base of Darlington transistor Q1. Hence, the indicator lamp driven by Q1 will flash on and off at the 0.5Hz rate. IC1c is a similar oscillator to IC1b except that it oscil­lates at about 1kHz. It is effectively gated on and off by the output of IC1b which pulls pin 8 low via diode D3. Thus, we have one second bursts of 1kHz oscillation from pin 14 of IC1c. IC1d acts as a buffer for the pulsed square wave output of IC1c. Its pin 10 is tied to pin 9, while pin 11 is tied to pin 14. Complementary transistors Q2 and Q3 are driven by the output of IC1d via a 10Ω resistor. These transistors in turn drive an 8Ω loudspeaker via a 47Ω limiting resistor and a 2.2µF capacitor. A separate power supply is provided for Q2 and Q3 via diode D2 and is decoupled with a 0.1µF capacitor. This separate supply prevents the speaker from emitting a squawk when power is turned off at the ignition switch. With the circuit values shown, the resistance between the sensor and the chassis of the car via the coolant needs to be less than 140kΩ for the alarm A number of holes must be drilled through one end of the case, directly in front of the loudspeaker. not to trigger. In practice, in cars with inhibitor added to the coolant, the resistance is typically less than 15kΩ. Construction The PC board for the coolant level alarm is coded 05305941 and measures 98 x 59mm. It is designed to snap into a standard plastic case measuring 130 x 68 x 40mm. Fig.2 shows the component overlay. Begin the board assembly by installing PC stakes at the five external wiring points. This done, install IC1, the zener diodes, the diodes and the resistors (take care with the orienta­tion of the semiconductor devices). Transistors Q1-Q3 can now be installed but make sure that you don’t get Q2 and Q3 mixed up. Q1 must be oriented so that its metal face is towards diode D2. Finally, mount the capacitors in position on the board. June 1994  23 RADIATOR NUT (REDUCE TO 14mm O.D.) RADIATOR NUT FOR COOLANT SENSOR IN-HOSE ADAPTOR BRASS FITTING This Temperature Gauge Adaptor kit is made by Specialty Automotive Products & is avail­able from Robbos Spare Parts – see parts list. ENLARGE HOLE TO 12.5mm DIA. TO ACCEPT NUT SPIGOT Fig.3: this diagram shows how the radiator nut is installed inside the brass fitting supplied with the in-hose adaptor. Note that you will need to file the corners off the nut & enlarge the hole at the bottom of the brass fitting to accept the nut spigot. This view shows how the coolant sensor can be fitted to the adaptor by forcing it into the unthreaded hole. We don't particularly recommend this method, however, as the fitting could leak or the sensor could blow out. Fig.4: this is the full-size etching pattern for the PC board. Once the PC board has been completed, drill holes in the case to accept the rubber grommet and to mount the loudspeaker. You will also have to drill a series of holes in front of the loudspeaker cone area to allow the sound to escape. This done, mount the loudspeaker using 2.5mm screws and nuts and clip the PC board in po24  Silicon Chip sition. Finally, fit leads to the external wiring points (+12V Ignition, Ground, Sensor and Indicator Lamp) and wire up the loudspeaker using light-duty hook-up wire. Testing The circuit is easily tested using a 12V power supply and a tin can filled with water to simulate a radiator. To do this, connect the indicator lamp and coolant sensor to the PC board, then connect the tin can to the GND lead using an alligator clip lead and apply power. When the sensor is in the water (don’t let it touch the sides of the can), the alarm should be silent. If the sensor is now removed from the water, the alarm should sound and the indicator lamp should flash after about five seconds. Installation As noted above, the coolant sensor should be mounted in the top radiator hose using an adaptor. There are two ways of doing this: the butcher’s way and the fussy way. One of our photos PARTS LIST Our preferred method for fitting the coolant sensor involves screwing it into a radiator nut which is first soldered to the inside of the brass adaptor fitting (see Fig.3 for details). The connection to the sensor is made using an automotive slide-on connector. The corners of the brass radiator nut must be filed down to reduce its outside diameter to 14mm so that it will fit inside the brass adapter fitting. shows the butcher’s way, whereby the plastic thread of the cool­ant sensor is forced into the unthreaded hole of the radiator adaptor. This method would probably be leak-free but we don’t like it. The alternative method is to solder a 14mm AF radiator nut (to suit the coolant sensor) into the radiator adaptor. This will allow the coolant sensor to be screwed into the in-hose adaptor and provide a gas tight seal. First, you will need to file the corners off the nut so that it will fit neatly into the in-hose adaptor brass fitting as shown in Fig.3. The hole in the bottom of the in-hose adaptor brass fitting will also need to be enlarged using a reamer so that the spigot on the radiator nut can be inserted. This done, solder the nut into the in-hose adaptor brass fitting using a blow torch and 50:50 solder. Follow the instructions on the back of the in-hose adaptor packaging when installing it into the hose. First, remove the top radiator hose and cut a 19mm diameter hole into it near one end. This will allow the threaded brass fitting to be inserted from the inside of the hose. The rubber washer must be placed on the brass fitting before it is placed inside the hose. The curved plate is then fitted over the threaded portion of the fitting (outside the hose) and the assembly secured with the nut. The coolant sensor now simply screws into the adaptor. You can now refit the top radiator hose to the vehicle and top up the coolant to replace any that was lost. The alarm unit itself can be mounted in a convenient place under the dashboard while the warning lamp should go on the dashboard so that it can be easily seen. Ignition connection The connection to the ignition circuit should be made after the ignition fuse. The ground connection is made by crimping the earth lead to an eyelet which is bolted to the chassis. Finally, run the lead to the coolant sensor, by passing the lead through the firewall (use a grommet) and along to the radiator. Tie down the lead using cable ties so that it follows the normal wiring harness paths. The connection to the sensor is made with an automotive slide-on connector. 1 PC board, code 05305941, 98 x 59mm 1 plastic case, 130 x 68 x 40mm 1 coolant level sensor (Ford part XF10K889A) 1 brass radiator nut suitable for the Ford sensor 1 Temperature Gauge Adaptor (Specialty Automotive Products – from Robbos Spare Parts, 345 Princes Hwy, Carlton, NSW; also from other Robbos stores 1 30mm 8Ω loudspeaker (Altronics Cat. C-0606) 1 12V indicator lamp 5 PC stakes 1 10mm rubber grommet Semiconductors 1 LM339 quad comparator (IC1) 1 BD681 NPN Darlington transistor (Q1) 1 BC337 NPN transistor (Q2) 1 BC327 PNP transistor (Q3) 2 1N4004 1A rectifier diodes (D1,D2) 1 1N4148, 1N914 diode (D3) 1 16V 1W zener diode (ZD1) 1 4.7V 400mW zener diode (ZD2) Capacitors 2 100µF 16VW PC electrolytic 1 10µF 16VW PC electrolytic 1 2.2µF 16VW PC electrolytic 2 0.1µF MKT polyester 1 .0047µF MKT polyester Resistors (0.25W, 1%) 2 1MΩ 1 1kΩ 10 100kΩ 1 47Ω 4 10kΩ 1 33Ω 1 6.8kΩ 1 10Ω 1 3.3kΩ Miscellaneous Automotive cable, insulated connectors, screws, nuts, cable ties. All that remains now, is to test the unit in the vehicle. Normally, the alarm will not sound when the ignition is turned on. To test the unit, short the sensor to the GND terminal on the temp­erature adapter plate and check that the alarm sounds and that the indicator lamp flashes after about five seconds. Check that the alarm can SC be readily heard inside the car. June 1994  25 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 The emperor’s new clothes – magnificent! Technology is magic, isn’t it. The media & the marketing people make out that technology can achieve virtually anything & that anyone can do it with no training required. The reality is quite different. By KRIS McLEAN* Did you see the McDonald’s ad that was run on TV recently – the one where the youngster sends his toy car out for a Big Mac? Pretty neat, eh! It depicted a scenario that was almost plausible to the casual observer. Mind you, that was no ordinary messenger he despatched. For a start, there was the live video feed back from the vehicle and that extraordinary digital propor­tional remote control, good for at least a couple of city blocks through all that urban clutter. And what of Junior himself? How many ankle biters would be capable of throwing such a system together? The fact is, the scenario depicted is 7-segment processor speed display packed it in the day after you got the machine. OK, so now your secretary or the kids have tired of playing patience and watching the cards jump and you (they) decide it’s time to populate one of the motherboard slots with a card. Does­ n’t matter what kind of card; it could be a modem or scanner or anything. So you just plug it in, set a few DIP switches or click a few menu boxes and it runs. I mean that’s what the salesman said, right? Wrong! Maybe it does run. But only after you’ve navigated the maze of IRQ clashes, DMA conflicts, port “Why is there such a yawning chasm between the myth of black box inter-connectivity and the reality of what can actually be achieved with finite resources?” possible but unlike­ly. And it mirrors beautifully the hype thrust at us all these days about what can be achieved with technology and, in particu­lar, just how easily it can be achieved. Take the humble 486 PC, for example. You bought it from a reputable company bundled with some software, so there is a fair chance that it actually runs. This is by no means a certainty Probably you have played with it a bit and monstered the supplier about the mouse driver that locks up between Windows and DOS and perhaps the contentions and assorted software incompatibilities that no one, including the team that designed the systems, fully comprehends. If you are serious about the new card, allow at least a full day to get it working - I do. The exercise can be like walking through a mine­field and it’s not just the little people like you or I that get caught. I’ve watched big outfits with impressive resources go around problems like this rather than go through them. I’ve seen PhDs scratch their heads in disbelief at the seemingly intract­able problems that can arise from attempting to launch the sim­plest of ‘plug & play’ concepts. So what has brought us to this sorry state. Why don’t these systems just click together like ‘Lego’ blocks? Why is there such a yawning chasm between the myth of black box inter-connectivity and the reality of what can actually be achieved with finite resources? And why can’t Junior dispatch an automaton to fetch dinner without crippling the family’s finances in the process? Well, it’s not proprietary pig headed­ ness; that single minded, blinkered philosophy that leads people to design delib­ erately incompatible systems with a view to achieving some sort of perceived advantage over the competition. These days, that approach is more likely to achieve product oblivion than any sort of market share. No, it would seem that the global producers really do try hard to achieve some sort of standardisation, at least at the interfaces. The problem is threefold. First, there is the extraordinary complexity underlying the simplest of functions. The technical community has laboured long and hard to mask the machinations of what lies behind the seem­ingly routine. Just try writing your own printer driver and you will see what I mean. The situation reminds me very much of a question I naively asked a Biochemistry professor years ago? “Why” I queried, with blocked nose and puffy eyes, “was the medical research community taking so long to cure the common cold?” The old boy eyed me patiently. “Because lad, the designer of the common cold has pulled out all stops. You are talking about complex chemistry at the base molehom life itself”. There are limits to the degree of understanding attainable with a “black box” or systems approach to Continued on page 93 June 1994  29 By DARREN YATES An 80-metre AM/CW transmitter for amateurs You don’t need lots of money to get started on the 3.5MHz amateur band. This low-power transmitter puts out about 100mW PEP, is powered by a 6V battery & is ideal for use by novice & QRP operators. This little transmitter won’t set the world on fire with its performance but, on a dollar-for-dollar basis, you won’t find much better in terms of simplicity. And if you enjoy the chal­ lenge of operating QRP (ie, at low-power), then this unit is just the shot. Operating QRP is a real test of skill when it comes to chasing those distant DX contacts. In order to keep it as simple as possible, and in the interests of stability, 30  Silicon Chip the transmitter is crystal-locked to 3.579MHz. This puts in right slapbang in the middle of the novice band (3.525-3.625MHz), so it is an ideal way to get start­ed in amateur radio – there’s no need to lash out on expensive gear and you gain the experience of building and operating your own transmitter. Other features of the design include the ability to operate either CW (Morse) or AM (voice) at the flick of a switch, and the use of bog-standard components. Most transmitter designs require a swag of handwound coils which are used in the output-stage filtering and tuning stages. By contrast, this circuit uses standard pre-wound RF chokes which look just like 1W resistors (and, in fact, are installed in exactly the same manner). You can’t make things much easier than that! Another good feature of the design is that it’s portable, an important consideration if you want to “go bush”. The power comes from four 1.5V AA cells which should give about 20 hours continuous operation in most conditions. By the way, you must have an amateur radio licence before using this transmitter. If you don’t already have a licence but are interested in amateur radio, you can find out more by contacting the Wireless Institute of Australia (WIA) in your state. How it works Fig. 1 shows the circuit for the 80-Metre AM/CW Transmit­ter. As you can see, there isn’t much to it – just a handful of common transistors, a crystal, a couple of pre-wound RF chokes and a few passive components. Transistor Q1 is connected as a Colpitts oscilla­tor whose frequency is set by a 3.579MHz NTSC TV colour burst crystal (X1) This stage oscillates by virtue of the feedback path provided by the .001µF and 100pF capacitors and the crystal itself. The output appears at the emitter of Q1 and is buffered by emitter follower stage Q2. This is done to prevent loading of the oscillator output which would otherwise cause it to stop. After that, the signal is split along two paths and used to drive two different stages: (1) a voltage doubler/ diode pump stage based on D1 and D2; and (2) an output amplifier stage based on Q4. The voltage doubler/diode pump stage converts the 3.58MHz signal into a steady DC voltage. This DC voltage then switches on transistor Q5 which in turn lights LED 1 to indicate that the carrier signal is present. In addition, the output from D2 provides the bias All the parts, including the 4-way battery holder, fit neatly inside a small plastic case. Make sure that switch S1 is correctly oriented on the front panel & check that none of the parts short together when the lid is closed. for driver stage Q3, either via switch S1 (for AM operation) or via KEY 1 (for Morse code operation). This may seem a little unusual but it ensures that if, for some reason, the carrier signal fails to appear, the output stage isn’t wasting current trying to transmit something that doesn’t exist. The AM (amplitude modulated) signal is also fed in at this point. This can come from just about any source (eg, a microphone preamplifier) and is applied via a 0.1µF capacitor and a 10kΩ level pot (VR1). After that, the signal passes via a 4.7kΩ resis­tor and is mixed with the bias voltage before being applied to the base of Q3 via S1 (for AM mode). Switch S1 controls the mode of transmission. With S1 open, KEY 1 is called into play and the transmitter S2 +6V ANTENNA 100 16VW 330  6V A  LED1 Q1 BC548 C B 68k X1 3.579MHz Q2 BC548 10k B C Q5 BC548 10k S1 C E 1.5k 100pF 100pF B E E .001 K +6V 0.1 100pF D2 1N914 1k 10k 3.3k B 4.7k 470  .001 B E 0.1 C VIEWED FROM BELOW A K AM INPUT +6V C L1 2.2uH 680pF E 0.1 0.1 D1 1N914 KEY1 Q3 BC337 Q4 BC337 B 100pF 100pF 100pF L2 4.7uH L3 2.2uH C 180pF E 180pF VR1 10k 80M CW/AM TRANSMITTER Fig.1: the transmitter operates on 3.579MHz, as set by the Colpitts oscillator based on Q1 & crystal X1. June 1994  31 Fig.2: install the parts on the PC board & complete the wiring as shown in this diagram. Make sure that all parts are correctly oriented on the board & be careful not to confuse the transistor types. MORSE KEY LED1 S1 VR1 A K 6V BATTERY 0.1 10k X1 D1 operates in CW mode. Note that you need to remember to remove the AM input when operating CW. With S1 closed, KEY 1 is bypassed and AM signals are fed to the base of Q3 via a low-pass filter consisting of a 3.3kΩ resis­tor and a 100pF capacitor. This filter network attenuates any unwanted RF signals in this part of the circuit. Transistor Q3, a BC337 NPN type, is used as a driver for the main output stage, Q4 (another BC337). This stage is also driven by the carrier signal which appears at the emitter of Q2, as described earlier. A 100pF capacitor to ground from the base of Q4 provides some light filtering and improves the quality of the carrier signal. Basically, Q3 controls the bias applied to the base of Q4. In CW mode, 3.3k D2 0.1 Q2 10k 100pF S2 LED1 A K Q5 10k L3 L2 100pF 1k Z .001 Q1 1.5k +6V 68k 0.1 ANTENNA L1 4.7k 330  .001 100uF Q3 680pF 470  AM INPUT +6V 180pF Z GND 100pF 100pF Q4 180pF KEY 1 turns Q3 on and off and this, in turn, switches Q4 on and off. Thus, each time KEY 1 is pressed, Q4 is biased on and a burst of carrier signal is fed to the antenna circuit. When AM operation is selected, the signal on Q3’s emitter continuously varies the bias applied to Q4 and so Q4 amplitude modulates the carrier. Output stage Q4 operates as a common emitter amplifier with a parallel LC circuit making up a tuned collector load. This tuned circuit consists of a 2.2µH inductor and a 680pF capacitor and has a fre­quency of resonance which is close to the 3.58MHz carrier fre­quency. This not only ensures maximum gain at the desired frequen­cy but helps to remove unwanted harmonics as well. From here, the signal passes through an output filter stage consisting of inductors L2, L3 and their associated capacitors. L2, L3 and the 180pF capacitor to ground form a low-pass filter which rolls off the response below 4.5MHz, while L3 and its parallel 180pF capacitor form a notch filter which is centred on about 7.2MHz (the notch frequency is also set, to some extent, by the second 180pF capacitor). This notch filter is used to curtail the second harmonic, so that we are left with a carrier sinewave of quite good purity. The reason we are after a pure sinewave is to prevent interference to other frequencies in the RF spectrum. Finally, a 100pF ceramic capacitor decouples the antenna from the output stage. The antenna should be RESISTOR COLOUR CODES ❏ No. ❏  1 ❏  3 ❏  1 ❏  1 ❏  1 ❏  1 ❏  1 ❏  1 32  Silicon Chip Value 68kΩ 10kΩ 4.7kΩ 3.3kΩ 1.5kΩ 1kΩ 470Ω 330Ω 4-Band Code (1%) blue grey orange brown brown black orange brown yellow violet red brown orange orange red brown brown green red brown brown black red brown yellow violet brown brown orange orange brown brown 5-Band Code (1%) blue grey black red brown brown black black red brown yellow violet black brown brown orange orange black brown brown brown green black brown brown brown black black brown brown yellow violet black black brown orange orange black black brown This close-up view shows the completed PC board assembly. Use PC stakes at the external wiring points & keep all component leads as short as possible. a 10-metre length of hook-up wire and should be about 10 metres above ground if possi­ble. The ground connection can be taken from the board to a stake in the ground. Power for the transmitter is supplied by four “AA” alkaline cells. The transmitting current is approximately 70mA so alkaline cells should give about 20 hours of continuous use. Note that Q4 is always biased on by an AM modulated base current when operating in the AM mode. The result is that if you increase the supply voltage beyond 6V, the current consumption quickly rises to about 100mA (at approx. 8V). This, in turn, will lead to a rapid rise in Q4’s temperature and, eventually, it will self-destruct. Even with brand-new cells, the circuit is perfectly reli­ able and no problems should be found if you stick to the 6V supply specified. Construction Most of the parts for the 80-Metre CW/AM Transmitter are installed on a PC board coded 06106941 and measuring 101 x 39mm. Check your PC board against the published pattern (see Fig.4) before installing any of the parts, to make sure that the board has been etched correctly. It’s much easier to find and correct any prob­lems at this stage rath- er than later on when the parts have been mounted. Fig.2 shows the parts layout on the PC board. Begin the assembly by installing PC stakes at the external wiring points, then install the resistors, inductors and diodes. Note that, because sections of this circuit handle RF signals, it’s import­ant to keep all component leads as short as possible. Check that the diodes are correctly oriented, then complete the board assembly by installing the capacitors, PARTS LIST 1 PC board, code 06106941, 101 x 39mm 1 front panel label 1 zippy case, 130 x 68 x 41mm 1 black 4mm socket 1 black 4mm plug 1 red 4mm socket 1 red 4mm plug 1 3.579MHz colour burst crystal 1 SPDT toggle switch 2 3.5mm socket 1 5mm LED bezel 1 knob 6 PC stakes 1 AA x 4-cell long battery holder 1 9V battery snap connector 1 10kΩ log pot 1 10-metre length of hook-up wire (antenna) Semiconductors 3 BC548 NPN transistors (Q1,Q2,Q5) 2 BC337 NPN transistors (Q3,Q4) 1 5mm red LED (LED 1) 2 1N914 diodes (D1,D2) Capacitors 1 100µF 16VW electrolytic 3 0.1µF 63VW MKT polyester 2 0.001µF ceramic 1 680pF ceramic 2 180pF ceramic 4 100pF ceramic Inductors 1 4.7µH RF inductor (L2) 2 2.2µH RF inductors (L1,L3) Resistors (0.25W, 1%) 1 68kΩ 1 1.5kΩ 3 10kΩ 1 1kΩ 1 4.7kΩ 1 470Ω 1 3.3kΩ 1 330Ω Miscellaneous Screws, nuts, washers, solder, hook-up wire. June 1994  33 80-METRE AM/CW TRANSMITTER AM AUDIO LEVEL CW TRANSMISSION KEY IN 3.58MHz CARRIER Fig.3: this full-size artwork can be used as a drilling template for the front panel. Use a small pilot drill to drill the holes initially, then carefully ream them to size using a tapered reamer. transistors and the 3.579MHz crystal. Be sure to install the correct transistor type in each location – Q1, Q2 and Q5 are BC548s, while Q3 and Q4 are BC337s. The crystal can go in either way around, since it is not polarity conscious. Final assembly The circuit board is designed to fit inside a standard plastic box measuring 130 x 67 x 42mm. As shown in the accompany­ing photo, the board sits in the bottom of the case, with the battery holder mounted down one side. Before mounting the board, attach the front-panel label to the lid of the case and use this as a template for drilling the holes for the front panel hardware. Note that these holes are best drilled using a small pilot drill and then enlarged as necessary using a tapered reamer. Once these holes have been drilled, mount the various items in position, then drill holes in the box for the power switch and audio input socket at one end and the antenna and ground sockets at the other. The PC board can now be positioned in the case alongside the battery holder and used as a template for marking out its mounting holes. Drill these holes to size, then secure the board using machine screws and nuts. The assembly can now be completed by installing the remain­ing items of hardware and running the necessary wiring connec­tions. Testing Check your wiring and the PC board assembly carefully before applying power. In particular, check that all components are in their correct locations and that the front panel wiring is correct. When you’re satisfied that everything is correct, connect your multi­meter (set to the 400mA range) in series with one of the power supply Fig.4: check your PC board against this full-size etching pattern before installing any of the parts. The board measures 101 x 39mm & is coded 06106941. 34  Silicon Chip leads, set S1 to CW (ie, S1 should be open) and apply power. You should find that the carrier LED is now lit and that the quiescent current is about 5-10mA. If the cur­ rent drain is much higher than this or if the LED doesn’t light, switch off and check the circuitry around Q1, Q2, D1-D2 and Q5. If everything appears to be OK, you can now check that the transmitter actually operates. To do this, you will (obviously) need a shortwave receiver or, more specifically, a receiver that will tune the relevant frequency (ie, 3.579MHz). If you don’t already have a receiver, then there are a number of low-cost units to choose from at your local electronics retailer. The final test simply involves making a transmission (note: you must have an amateur radio licence). To do this, connect an audio source to the AM input, switch S1 to AM and then tune to 3.579MHz on your receiver. Even with just a short length of antenna lead, you should have no problems picking up the signal on the radio. Note that, in this mode, the meter should register a cur­rent drain of 7080mA. If it’s more than this, switch off imme­diately and check for assembly errors. CW transmissions Most low-cost commercial receivers cannot receive CW trans­ missions, since they don’t include a BFO (or beat frequency oscillator). However, there is a way around this problem. If you do wish to transmit Morse code to one of these receivers, all you have to do is feed a 1kHz sine or square wave signal into the AM input and switch S1 to CW. That way, each time the Morse key is pressed, brief bursts of amplitude modulated signal are radiated by the antenna. Of course, if your receiver does have a BFO, you can remove the AM input and transmit straight CW only. Finally, note that the better the antenna used, the better the results from this little transmitter. Our tests were performed using a simple 10-metre long-wire antenna but more elaborate antennas should give better perforSC mance. High Purchase Costs Taking a “Bite” Out of Your Budget? NOT AT MACSERVICE. WE HELP YOU STRIKE BACK BY OFFERING THE LOWEST PRICES AND GOOD OLD FASHIONED SERVICE - Just look at these SPECIALS BALL EFRATOM M100 Rubidium Frequency • Factory cal. certs. • Perfect for ISO    accreditation • GPS applications • Ruggedised military    design TEKTRONIX 5440 Oscilloscope • DC to 60MHz • 1mV - 100V/div (x 10) • Dual Trace • Dual Timebase • Large Screen TEKTRONIX 7603 Oscilloscope • Mil spec AN/USM 281-C • Triggers to 100MHz • Dual Trace • Dual Timebase • Large Screen SUPER SALE $850 GREAT VALUE $2950 (new) Video Dist Amp & Cable Equaliser   $100 ADVANCE PP7 30V3A DC Power Supply   $150 AVO MK.IV Avometer With Cal.   $275 BPL CB154/4 Electrolytic Cap Bridge   $450 B&K 1466A 10MHz Oscilloscope   $275 EH 129 Pulse Generator   $90 ELGENCO 603A White Noise Gen 5MHz   $200 ENI 503L RF Power Amp 40dB 510MHz $1025 FLUKE 102 VAW Cal Meter    $75 FLUKE 9010A Logic System Troubleshooter $1000 GR 1608 LCR Meter – Lab Standard $1500 HP 211B 10MHz Square Wave Generator   $275 HP 302A Audio Selective Level Meter   $145 HP 400L True RMS Voltmeter   $170 HP 410B Vacuum Tube Voltmeter   $130 HP 432A 10GHz Power Meter (c/w sensor)   $875 SUPER DEAL $950 HP HP HP HP HP HP HP HP I/S Elect. 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SD112-1 Systron Don. 1037 Telequipment CT71 TRIMAX G1B VARIAC Mod Meter 1200MHz $1100 AM/FM Mod Meter   $550 LCR Bridge   $325 Universal Bridge in circuit   $700 Insertion Signal Analyser   $150 Log Freq-Voltage Converter   $150 100MHz GPIB Counter   $350 Decade Box   $150 1.6/18.6MHz Generator   $250 Controllable Phase Meter   $200 750VA Line Stabiliser   $180 Voltmeter Freq-Log Conv 2ch   $150 500MHz Counter   $350 Curve Tracer   $900 Ionisation Tester 10kV   $260 0/280V <at> 15A   $260 NEW METROLOGY INSTRUMENTS AT FANTASTIC PRICES!!! M36 $55 VCE 150 $120 CM 25 $45 SEPTEMBER SPECIAL TEKTRONIX 465M 100MHz Oscilloscope VCE-150 VCE-200 VCD-150 DI-10 DI-1 TDI-0.8 CM-25 CM-50 150mm/6" Electronic Digital Vernier in box $120 200mm/8" Electronic Digital Vernier in box $180 150mm x 0.02 Dial Vernier Caliper   $75 10 x 0.01mm Dial Indicator   $45 1" x 0.001" Dial Indicator   $45 0-0.8 x 0.01mm Test Dial Indicator   $95 0-25mm x 0.01mm Outside Micrometer   $45 25-50mm x 0.01mm Outside Micrometer   $55 The Name That Means Quality CM-75 50-75mm x 0.01mm Outside Micrometer   $65 CM-01 0-1" x0.001" Outside Micrometer   $45 MB-6 CZ-6C Magnetic Base Stand   $55 VC-150 Dual Scale Vernier Caliper 150 x 0.02mm/6" x 0.001"   $35 VC-200* Dual Scale Vernier Caloper 200 x 0.02mm/8" x 0.001"   $45 VC-600* Dual Scale Vernier Caliper 600 x 0.02mm/24" x 0.001" $250 HI-600 600mm/24" x 0.02mm Height Gauge $550 *WITH FINE ADJUSTMENT Affordable Laboratory Instruments SSI-2360 60MHz Dual Trace Dual Timebase Oscilloscope BRA BRAN D EQUIP NEW MENT ND EQUIP NEW MENT Bandwidth DC to 100MHz; Rise time <=3.5ns; Deflection factor 5mV/div to 5V/ div in 10 steps; DC accuracy ±2%; 2-channel display mode; Horizontal deflection - main & delayed timebases; A - 0.5s/div to 0.05µs/div in 22 steps; B - 50ms/div to 0.05µs/div in 19 steps; Trigger - main/delay sweep; Coupling AC, DC, LF Rejection, HF Rejection TOP VALUE $1150 • • • • • • 60MHz dual trace, dual trigger Vertical sensitivity 1mV/div. Maximum sweep rate 5ns/div. Built-in component tester With delay sweep, single sweep Two high quality probes $1050 + Tax PS303D Dual Output Supply • 0 to 30V and 0 to 3 amps • Four output meters • Independent or Tracking modes • Low ripple output $385 + Tax PS303 Single Output Supply PS305D Dual Output Supply PS305 Single Output Supply • 0 to 30V and 0 to 5 amps $430 + Tax • 0 to 30V and 0 to 3 amps • Two output meters • Constant current/voltage • Low ripple output $225 + Tax • 0 to 30V and 0 to 5 amps $260 + Tax IF IT’S NOT HERE WE CAN GET IT... CALL US FIRST OR CALL US LAST... BUT DON’T FORGET TO CALL US! MACSERVICE Australia’s Largest Remarketer of Test & Measurement Equipment 26 Fulton Street, Oakleigh Sth, Vic., 3167   Tel: (03) 562 9500 Fax: (03) 562 9615 **Illustrations are representative only Are you broke, impecunious, skint, destitute or just plain poor? If so, then these could be the speakers for you. Called the Stoney Broke Loudspeakers, they are cheap to put together & require no carpentry skills but still sound surprisingly good. The Stoney Broke Loudspeaker System By LEO SIMPSON T HERE AREN’T TOO many bar- gains around in loudspeakers these days so when Jack O’Donnell of Altronics in Perth proposed these “Stoney Broke Loudspeakers” for people on a budget, we were dubi­ous. Very dubious in fact. OK, so you’ve got two reasonable quality drivers and a simple crossover network but the idea of sticking them inside two plastic zippy boxes stuck together did not inspire us. Still, Jack was not about to be put off and he sent us a pair of these Stoney Brokes. We were so under-whelmed to see the package arrive that we left it behind the door for six weeks until Jack phoned several times and nagged us to take them home and have a listen. Eventually, very grudgingly, we did. I mean, there 36  Silicon Chip was no real incentive was there? But when we started to listen to them we had to admit that they didn’t sound too bad. In fact, as we later said to Jack O’Donnell on the phone, they sounded far better than he had any right to expect! Now we’re not going to turn around and say that these are the answer to an audiophile’s prayers but if you have a need for a compact pair of speakers for the bedroom or as “multi­ media” speakers for your computer, they are worth considering. They certainly sound better than most so-called “multimedia” speakers for computers. Actually, as we have already indicated, the speakers them­ s elves are quite good quality units. The tweeter is a dome unit with a 12mm diaphragm while the woofer is a nominal 100mm (4-inch) unit with a foam roll surround and an effective cone diameter of 80mm. It has quite a large ferrite magnet and a double layer voice coil 25mm in diameter. Its free-air cone resonance is 30Hz and in the right design of cabinet, it is probably capable of a quite respectable performance. Linking the two speakers is a 2-way crossover network centred on 3.5kHz with attenuation slopes of 6dB/octave for the woofer and tweeter. The inductor is ferrite cored while the capacitor feed to the tweeter is a non-polarised electrolytic capacitor. The cabinet is where the real wizardry has been wrought. What looks to be two standard black Jiffy plastic cases (Altron­ics Cat H-0202) have been cunningly attached front to front and PARTS LIST (for a pair of Stoney Broke enclosures) 2 plastic enclosures, with holes machined (see text) 2 100mm roll surround woofers (Altronics Cat. C-0629) 2 12mm dome tweeters (Altronics Cat. C-3010) 2 two-way 3.5kHz crossover networks (Altronics Cat C-4005) 2 12Ω 1 watt resistors 2 sheets of Innerbond wadding, 200 x 150mm 8 adhesive rubber feet 2 port tubes, 60mm x 27mm O.D. 8 3mm diameter 25mm long studs Miscellaneous Hookup wire, silicone sealant or PVC adhesive, solder Where to buy them Note: the complete kit is available from Altronics (Cat. C3200) for $89.95 a pair. whammo – a speaker enclosure is the result. You’d be amazed that such a thing could happen but the photographs don’t lie. No carpentry required If you’re not confident about your carpentry skills then this project will be doubly attractive. The kit comes with the plastic boxes already machined. Both speaker cutouts are there and the screw holes are countersunk where required. Assembly is just that – you put it together. You will need a screwdriver and a soldering iron though. The two cabinet halves are reasonably easy to distinguish. The front half or baffle is the one with the two big round holes for the speakers. The other half is the back. It has a slot for the speaker terminal panel and a 26mm round hole for the port tube. You attach the woofer to the rear of the baffle using the countersunk screws and nuts supplied. We suggest you use shake­proof washers under the nuts because once the speaker is put together it is permanently together. Make sure that the terminals for the woofer are facing towards the centre The kit for the Stoney Broke loudspeaker system comes with all parts, including machined plastic boxes. The tweeter is a dome unit with a 12mm diaphragm while the woofer is a nominal 100mm (4-inch) unit with a foam roll surround & an effective cone diameter of 80mm. of the baffle as this will make it easier to solder on the connecting wires. The woofer should sit centrally on the machin­ed aperture and will be a snug fit. The tweeter is mounted from the front of the baffle, again using countersunk screws, nuts and shakeproof washers. The three holes in the tweeter’s mounting flange will need to be opened up slightly to enable the supplied 4mm screws to be used. Now where do you put the cross­over network? That had us tricked since there are no holes drilled to mount it. Someone who is extremely canny at Altronics has worked out how to mount it without drilling holes. It is mounted by sliding it diagonally across one corner of the baffle section June 1994  37 This photo shows how the parts are mounted in the two halves of the case, prior to the wiring being installed. Note how the crossover network is installed by sliding it diagonally across one corner of the baffle section so that it is held in place by the PC board slots. Be sure to connect the positive terminal on each speaker to its appropriate terminal on the crossover network & note that the 12Ω resistor is installed in series with the negative terminal of the tweeter. The C & I inputs on the crossover network are connected to the input terminals. and it is held in place by the PC board slots. The photo tells the story. The board may need to be filed on one edge to allow it to slide into the cabinet half without distorting. Once in position and the wiring complete, it could be held in place with a couple of blobs of silicone sealant. 38  Silicon Chip We’ve included two photos with this article which show progress in assembly. The first of these show the hardware in place in both halves of the cabinet but with no wiring. The second photo shows the wiring from the crossover to the speakers. This is quite straightforward since the six terminals on the crossover board are clearly labelled; ie, W+ and W- for the woofer, T+ and T- for the tweeter, and C and I for common and input. The positive terminals of both speakers are indicated with red paint on the relevant solder lug. Note that the tweeter has three solder lugs. One of these is a dummy and is not connected to either side of the speaker voice coil but it is not for use in Irish loudspeaker systems. Instead, it provides a convenient tie-point for the 12Ω attenuator resistor which is wired in series with the tweeter. The port tube is a 60mm length of 27mm O.D. PVC tubing. It is a close fit in the machined hole in the rear half of the enclosure. Altronics suggest that it be held in place using silicone caulking compound. Our approach would be to use PVC adhesive as used by plumbers (ie, MEK-based) – it gives a much stronger result. Beware though: PVC adhesive must not be used indoors as it can damage your eyes and your respiratory system. Now for the final steps in putting the enclosure together. You need to insert a small sheet of Innerbond BAF (bonded acetate fibre) into the back half of the enclosure – you will need to cut a slit in the sheet to allow the port tube to poke through it. Altronics suggest the following method of assembly. First, fit four 3mm studs into the threaded pillars of one enclosure half – you need to hammer them in and be careful to make sure they go in straight otherwise you might split the pillars. This done, run a bead of silicone sealant around the mating edge of one half of the enclosure, then carefully push the two box halves together until the sealant pushes out from the mating surfaces. The two halves are then clamped together until the sealant sets. The excess sealant is then cleaned off using mineral turps or scraped off using a utility knife. Our suggested method Quite frankly, we don’t like the suggested method for assembling the enclosure because too much brute force is re­ quired. Our suggestion would be to glue the two enclosure halves together using PVC adhesive. The enclosure halves should be carefully lined up and then clamped in place. Use a minimum of adhesive because you cannot clean off the excess. SILICON CHIP FLOPPY INDEX WITH FILE VIEWER Either way, once the box is assembled, you are unlikely to get it apart again without destroying both halves. So which ever method you choose, make sure that all screws are tight and all connections are correct before the final assembly step. We sug­gest you also test the system on a music signal (low volume please, otherwise you will damage the woofer) to make sure that all connections are working. Where do you get em? Stoney Broke Loudspeakers are available from Altronics in Perth or any of their dealers. The cost is $89.95 for a pair (includes all components). We should make one final comment about their use as multi­media speakers in conjunction with a computer. Most so-called multimedia speakers have shielded magnets and so they can be positioned right next to your computer’s video monitor without fear of degrading the purity. The magnets on the Stoney Broke speakers are not shielded and so they should not be placed any­ where closer than 30cm from your video monitor. If you do place them on top of or next to your moni­tor you will grossly distort the picture and also degrade the purity so that the colours will be mottled and poorly defined. If that happens, the monitor will require degaussing which means a trip to your service agent and SC payment of a service fee. Disc size:   ❏ 3.5-inch disc   ❏ 5.25-inch disc ❏ ❏ ❏ ❏ ❏ ❏ ❏ Floppy Index (incl. file viewer): $A7 + p&p Notes & Errata (incl. file viewer): $A7 + p&p Bytefree.bas /obj / exe (Computer Bits, May 1994): $A7 + p&p Alphanumeric LCD Demo Board Software (May 1993): $A7 + p&p Stepper Motor Controller Software (January 1994): $A7 + p&p Printer Status Indicator Software (January 1994): $A7 + p&p Switchers Made Simple – Design Software (March 1994): $A12 + p&p Note: Aust, NZ & PNG please add $A3 (elsewhere $A5) for p&p with your order Enclosed is my cheque/money order for $­__________ or please debit my ❏ Bankcard   ❏ Visa Card   ❏ Master Card Card No. Signature­­­­­­­­­­­­_________________________ Card expiry date______/______ Name _____________________________________________________ PLEASE PRINT Street _____________________________________________________ Suburb/town __________________________ Postcode______________ Send your order to: SILICON CHIP, PO Box 139, Collaroy, NSW 2097; or fax your order to (02) 979 6503; or ring (02) 979 5644 and quote your credit card number (Bankcard, Visacard or Mastercard). ✂ This rear panel view shows the port tube & the spring-loaded input terminals on the Stoney Brokes. Use PVC adhesive to hold the tube in place & to provide an airtight seal. Now available: the complete index to all SILICON CHIP articles since the first issue in November 1987. Now you can search through all the articles ever published for the one you want. Whether it is a feature article, a project, a circuit notebook item, or a major product review, it doesn’t matter; they are all there for you to browse through. The index comes as an ASCII file on a 3.5-inch or 5.25-inch floppy disc to suit PC-compatible computers and you can use a word processor or our special file viewer to search for keywords. Now with handy file viewer: the Silicon Chip Floppy Index now comes with a file viewer which makes searching for that article or project so much easier. You can look at the index line by line or page by page for quick browsing, or you can make use of the search function. Simply enter in a keyword(s) and the index will quickly find all the relevant entries. All commands are listed on the screen, so you’ll always know what to do next. Note: requires CGA, EGA or VGA graphics card, IBM-compatible PC, MSDOS 3.3 and above. June 1994  39 SERVICEMAN'S LOG Around the world for sixpence No, that heading is not a travel agency’s advertisement; it is one from way back which, as I recall, implies a whole sequence of frustrating events which ultimately result in very little gain. And that was exactly how I felt by the time I had finished this particular job. To be more precise, I can honestly say that this job turned out to be one of the most frustrating I have encountered for a very long time. I very nearly decided not to relate it, however, because the fault eventually turned out to be something quite simple. The only reason I have told it is that it might help someone else. Or that someone else might be able to answer some of the questions it poses. The story concerns a Hitachi-Fujian 34cm colour TV set, model HFC1421B, chassis type F87PT. These sets are made in China and were originally marketed in Australia, several years ago, through a Chinese Trade Commission, with offices in the Sydney suburb of Botany. However, I can find no reference to them in the current directory. The owner’s complaint was that the picture was rolling but a quick check revealed that this was not the case; the Fig.1: this diagram shows the relevant portion of the circuit around IC501 in the Hitachi-Fujian HFC-1421B. The IC is at the top, with pin 40 near it’s bottom lefthand corner. R710 is near the bottom of the diagram, in line with pin 34 of the IC. 40  Silicon Chip set had not lost vertical hold, it had lost horizontal hold – something likely to be rather more complicated. And as I had no technical data for this set, my first job was to try to acquire at least a circuit. However, with the marketing situation apparently changed, I was unsure as to who to approach. So I contacted my retailer colleague who has sold a number of this brand – but not this model – in the past. It transpired that he had obtained his stock from a wholesale outlet in Canber­ra and he gladly supplied their name and phone number. They were very obliging but could not help directly. In­stead, they referred me to a Sydney firm, Cumberland Electronic Services, 120 Old Canterbury Rd, Lewisham 2049. Phone (02) 564 1700. If you are involved in servicing, I suggest that you make a note of that. I rang them and they were also very obliging. They put me onto their service department and the gentleman in charge was most helpful. Yes, they could supply either a copy of the circuit diagram for $5.00 plus $2.00 postage, or a complete manual for around $25.00. I decided that, for what looked like a fairly routine fault, I could probably get by with a circuit, although the price of the manual is quite reasonable compared with some prices quoted these days. So I posted off a cheque and, in a few days, had a photocopy of the circuit. And, as photocopies go, it was not bad. By that I mean that it was probably no worse than the original, which was obviously much reduced. At least most of the values were readable, or at least decipherable. But some of the closely packed lines were hard to trace. Anyway, it was a start. So why had the set lost horizontal hold? The heart of this part of the circuit is IC501, a TA7698AP. This is a large, complicated 42-pin IC which handles the video signal, sync separation, chroma signals and matrixing, etc. It also has pulse...”. In fact it looks like the top half of a slightly impure sine wave. But “from shaped”? Anyway, terminology aside, I decided that it was good enough. So what did that leave? If the horizontal oscillator was running free at a reasonable rate and reference pulses were being fed back from the horizontal output transformer, I reasoned that it looked like a sync pulse failure. A composite video signal from the front end of the set (pin 15 of IC201) is applied to pin 39 of IC501 (INV IN), goes through an inverting stage, and emerges on pin 40 (INV OUT); ie, the signal is inverted but otherwise unchanged. From here, the signal goes to pin 37 (SYNC SEP IN), which seems quite logical, except that there is a network of resistors, capacitors and a diode in between – see Fig.2. And it is around this network that I have encountered faulty components in the past. So, initially, I went over this network and checked every likely component, either by measurement or substitution. And I could find nothing wrong. But the mere presence of the network itself kept nagging me. What was its function anyway? Could there still be a subtle fault in it somewhere that I had missed? This was something I was unsure about without knowing what the network was supposed to achieve. Come in sucker the facility to be wired to handle PAL, NTSC or SECAM signals. It is a very commonly used IC and is found in a variety of brand names. These include AWA, NEC and Orion. And it so happens that I have an AWA manual in which there is a section purporting to describe some of the associated circuitry. Among other things, it has an enlarged and detailed diagram of the IC, with designa­tions for the various pins – something not available on the Hi­tachi circuit. I have included these designations in brackets in the following discussion. I concentrated on the circuitry around the sync separator section, partly because I have had problems here before. In particular, I remembered encountering both vertical and horizon­tal sync problems in this area. But there were a couple of other symptoms supporting this idea. Most important was the fact that, by carefully adjusting the horizontal hold control (R709) and riding it, it was possible to hold the picture on the screen. This suggested that the free-running frequency of the horizontal oscillator was not grossly out and that it should be capable of locking if the sync pulses were being processed correctly. Further to this thought, I checked the horizontal pulses from the horizontal output transformer, which are used for com­parison in the AFC circuit. These come from pin 7 of the trans­former and are fed into pin 38 (H PULSE IN/GATE PULSE OUT) of the IC. There was a substantial pulse here, similar to one shown in the AWA manual and described as “a from shaped horizontal flyback I suppose that, at this stage, I allowed myself to be sucked in to some extent. I felt I should try to understand the circuit, at least for future reference, rather than simply check each component until I found a crook one. A noble sentiment, perhaps, but not necessarily a very practical one. One reason I pursued this approach was that, as I mentioned before, the AWA manual purports to explain the purpose of this network. If I could digest that, I might have learned something. Alas for my hopes. The explanation turned out to be a mess of badly-translated gobbledegook, with spelling, grammatical, and composition mistakes that went far beyond the ones we regularly encounter. Taken together, they added up to incomprehensible garbage (I should have been warned by that “from shaped” pulse reference). June 1994  41 heels. As far as I could tell, the external network between pins 37 and 40 was intact, the horizontal reference pulse from the horizontal output transformer, was correct, and I had replaced the IC. What had I overlooked? Back to the circuit According to the screed, “The composite video signal from pin 40 is applied (to pin 37) through a sync separator time constant circuit. The slice levels of the horizontal sync and vertical sync can be set independently”. So now we know! Or we might if we were sure what is meant by slice level – I could hazard a guess – and, more importantly, why it is apparently so critical. And what is the purpose of the “time constant”, which is also mentioned? I went over the screed several times, cooked up several theories which had to be discarded, and discussed it with several colleagues. They all shrugg­ed their shoulders and one, to whom I complained about the standard of 42  Silicon Chip service manuals, muttered something along the lines of “that’s life”. Well, I know when I’m beaten. I had wasted a lot of time and achieved nothing more than a sense of frustration. I seemed to have exhausted all the possibilities I could think of. So what was left? The IC? Not very likely and only as a last resort. But this seemed like a last resort situation. And I did have a spare on hand. Oh well, at least it would prove the point, one way or the other. It is not such a big deal these days, even with 42 pins involved. Twenty minutes later I was ready switch on again, fingers crossed. It was an anticlimax; the fault was still there, exactly as before. Well, that really set me back on my I spent some time pouring over the circuit again. As I’ve already stated, some of the lines were very crowded, making some long runs very difficult to follow. And this was part of the reason I had missed out on a vital section. I went back to pin 7 of the horizontal output transformer and once again, but more carefully this time, traced the circuit up to pin 38 (H PULSE IN etc). And I suddenly realised what I had missed. Branching off this rail was resistor R701 (8.2kΩ). And this led me to R706, a 2kΩ preset tab pot, shunted by R707 (2.2kΩ) and connected to chassis via capacitor C709 (.01µF). This tab pot is what some makers call horizontal AFC, or horizontal position, among other names. The moving arm of R706 goes to pin 35 (AFC OUT) via C707 (.022µF) and its obvious func­tion is to allow the level of the reference pulse to this pin to be optimised during manufacture. Of course, the fault just had to be in this little branch of circuitry which had been overlooked. And it was – R701, the 8.2kΩ resistor, was virtually open circuit. When it was replaced, the picture locked up instantly and set was ready to go back to the owner. But why was it overlooked? There is no point in trying to make excuses; if you goof, you goof. The best one can do is try to learn from it. But I think it is fair to say that the crowded nature of the circuit didn’t help, although that is something we have to learn to live with. Another factor, and again this is no excuse, was that the offending resistor was not mounted anywhere near the cluster of other components around the IC, which I had tested as a matter of routine without too much regard for their place in the circuit. No, it was mounted over near the horizontal output transformer, where it connected to pin 7. Of course, it was all perfectly logical from the physical layout point of view. So there it is; a happy ending for the customer but a very unhappy INVERTER OUTPUT 40 R550 2.7k R551 820  R552 620k D591 C563 1 C564 .01 SYNC SEP INPUT 37 R565 56k C513 560pF Fig.2: this network between pins 37 & 40 of IC501 in the Hitachi-Fujian HFC-1421B has been redrawn from an AWA manual & given the component markings from the HFC-1421B circuit. experience for yours truly. That one won’t be putting any cream on the custard – it won’t even pay for the custard! Bread & butter Well, after all that, I think that something a little less traumatic is called for; something more in line with the routine day-to-day, bread-and-butter jobs. (Why do I keep talking about tucker?) Anyway, this is a story about a video recorder; a Hitachi model VTM818E. This is a current model and the particular unit was virtually new, being only about three months old. That means, of course, that it was still under warranty. What follows is not about any long and involved diagnosis; the fault was plainly visible. The real point is the unlikely coincidence of the forces involved. The lady who brought it in was quite clear about the prob­lem; it would load a cassette, apparently correctly, but would not play it. It would not respond to the play button; at least not properly. It would commence to play the tape but would run for only about 10 seconds before stopping. I didn’t doubt the lady’s description but I must confess to being a little surprised by it. It sounded like a mechanical fault of some kind but that would be very unusual for a machine with only three month’s use – and particularly with this model, which is a very reliable one. After the lady had left and I had finished another job, I set it up and pushed in a tape. It loaded normally, so I pressed the play button. And it behaved exactly as described; it ran for about 10 seconds, then shut down. I pushed the eject button and the cassette unloaded normally. OK, time to pull the cover off and look at the works. The layout is fairly conventional, with the tape deck on the lefthand side and the PC board to the right. I could see nothing obviously wrong, so I pushed the tape in again and watched it load. This appeared to be normal. The machine employs the now fairly common “half load” procedure; as soon as the cassette settles on the deck, the tape is loaded against the control head, an arrangement designed to measure and display the actual playing time of the tape while it is being shuttled. Then, when the play button is pressed, the loading arms pick up the tape and Subscribe now to the largest faults & remedies library in Australia ✱ ✱ 1994 manuals are now available. Our database is regularly updated with information supplied by technicians such as yourself. ✱ Exclusive backup service by qualified technicians. ✱ ✱ Over 10,000 faults and remedies on file with flow charts and diagrams. Covers Colour TVs and VCRs of all brands sold in Australia EFIL Phone or fax now for your FREE information package ELECTRONIC FAULT INFORMATION Reply Paid 4 P.O. Box 969 AIRLIE BEACH 4802 Ph 079 465690 Fax 079 467038 June 1994  43 SERVICEMAN’S LOG – CTD wrap it around the drum in the usual way. And that is exactly what happened. The tape began to move, the take-up and supply reels revolved, and nothing appeared to be amiss. At least, not for the first few seconds. Then, suddenly, the take-up reel stopped and the tape kept coming, forming a loop. I was reaching for the on/off switch, when the whole system shut down. Well, that was normal too. The loss of sensing pulses from the take-up reel had indicated to the microprocessor that there was something wrong and it had done its job – including rewinding the loop back onto the supply reel, to avoid further damage. So all I had to do was find out why the take-up reel was malfunc­tioning. And it was malfunctioning in a rather peculiar way. Further observation, using a clear plastic dummy cassette, allowed me to see the takeup reel directly and revealed that it always made exactly one revolution before it failed. I unloaded the dummy cassette and made a closer examination of the take-up reel. Turning the reel with my fingers confirmed that it was meeting some obstruction after one turn. And looking more closely it appeared that there was something stuck to the side of the reel. But in the confined space of this par­ticular unit, I was unable to see what it was. I decided that the simplest approach would be to remove the cassette carrier. While this job is a bit fiddly, it is no big deal provided the screws are removed in the right order. I won’t bore the reader with the procedure – it varies from machine to machine anyway – but it does involve un­clipping the front panel of the machine and moving it out of the way. That done, the carrier can be slid slightly towards the front of the machine, allowing a couple of locking keys to be freed from their keyways. The carrier can then be released and laid to one side – the lead lengths are quite adequate – thereby providing ready access to the reel mechanisms. The nest step was to remove the reel itself. It is held in place with a small circlip, the only precaution being to ensure that the circlip doesn’t fly off to the other side of the workshop. Well it didn’t and I was then able to lift the reel free. Brake mechanism And now all was clear. What we were looking at was the brake pad from the brake assembly of the take-up reel. The brake mechanism consists of a brake shoe which is fitted with a felt pad. The brake shoe moves horizontally and presses the pad against the side of the reel, to prevent tape overrun when the transport mechanism stops. But there was no brake pad on this brake shoe, where it should have been; instead it was stuck to the side of the reel. And that was what was hindering the rotation of the take-up reel and causing the machine to shut down. On Sale Now At Selected Newsagents Or buy direct from SILICON CHIP Price: $7.95 (plus $3 for postage if ordering from Silicon Chip). Order today by phoning (02) 979 5644 & quoting your credit card number; or fax the details to (02) 979 6503; or send cheque, money order or credit card details to PO Box 139, Collaroy, NSW 2097. 44  Silicon Chip Now missing brake pads are fairly common, though not in machines only a few months old. More importantly, they don’t cause this kind of problem. Instead, they usually simply fall to the bottom of the machine and, in most cases, the user is not even aware of what has happened; the bare brake shoe usually continues to do the job, even if a little less scientifically. It is only when the machine is opened for some other reason that this fault is found. The brake pads are attached to the brake shoe with some kind of contact adhesive on the back of the pad. Exactly why this failed, allowing the pad to come free, is not clear. But what is apparent is that, when it did come adrift, it flipped over so that the adhesive side was pressed against the side of the reel, and it stuck there. And it was right in the path of the brake shoe, so that it fouled it after the first revolution. The cure was simple enough. Peel off the pad, clean off any adhesive it may have left behind, then refit it to the brake shoe. But I added some extra adhesive this time; a dab of Selleys Kwik Grip® – reputedly strong enough to mend a broken heart! Anyway, it should do this job adequately. As I said at the beginning, it was no big deal to find and fix, but it surely must have been one chance in a thousand that the pad behaved as it did and finished up where it did. So I can hardly expect that this story will have anything more than novelty value; I don’t imagine that anyone else will ever encounter the same fault. Still, stranger things have hapSC pened. 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 ORDER FORM BACK ISSUES MONTH YEAR MONTH YEAR PR ICE EACH (includes p&p) TOTAL 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. $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 June 1994  53 Need another pair of audio inputs? Convert the phono inputs on your amplifier Do you need another pair of line inputs on your stereo amplifier? And do you no longer use the phono inputs? Well, here’s the answer – convert the phono inputs to normal line inputs & presto, another pair of inputs. By LEO SIMPSON Let’s face it, most people these days do not listen to vinyl records and have long since dispensed with their turntable, if indeed they ever had one. So the phono inputs on their stereo system are unused and useless. But these same people often also need another pair of inputs so they can hook in an extra tape deck, VCR or other program source with line outputs. What to do? Until now, there wasn’t much of an answer. If you knew your way inside an amplifier or stereo receiver, you could whip out the phono preamplifier and rewire the inputs as straight line inputs but that is an option few people would care to take. Some people may also still have a turntable which they want to able to use from time to time but want the option of using the phono inputs for line level inputs. The solution is to convert the phono inputs to line inputs via an external adaptor box and for this idea we are indebted to Gary Johnston of Jaycar Electronics. Essentially, all phono inputs provide a great deal of am­ plification (about 34dB or 50 times, at 1kHz), as well as RIAA equalisation for the signal from magnetic cartridges. The RIAA equalisation curve provides lots of bass boost at very low bass frequencies (approaching +20dB at 20Hz), tap­ering down to zero at 1kHz. Beyond 1kHz, the circuit applies treble cut and this in­creases as the frequency rises so that at 20kHz, the cut is almost 20dB. The general slope of the attenuation is -6dB octave right across the frequency range but there are two inflections in the curve at 500Hz and 2kHz (2122Hz, to be precise). So to convert the phono input to a line input with a sen­sitivity of around 100mV at 1kHz, you need a circuit which will provide about 34dB attenuation overall and a filter character­is­ tic which is exactly the reverse of the RIAA equalisation – see Fig.1. This may sound as though a fairly complicated circuit is required but in practice it turns out to be quite simple. Circuit details Our prototype inverse RIAA network was built into a relatively large metal diecast case & fitted with a Dynamark self-adhesive label to dress it up. It enables the phono inputs on your amplifier to be used with line level sources such as tape decks or a VCR. 54  Silicon Chip The suggested circuit is shown in Fig.2. The circuit is passive; ie, it has no active components such as transistors or integrated circuits and no power supply is needed. Actually, while the circuit is quite simple, a good deal of design work has gone into it to make sure that it does the job. As you can see, it involves just three resistors and two Performance We used our prototype converter with a number of commercial amplifiers and also with our latest Studio series remote control preamplifier as described in the September, October +20 +10 DECIBELS capaci­tors for each channel. So how did we go about designing this little network? First of all, we had to consider the type of source which would feed the circuit. Now all program sources, whether they are a CD player, tape deck, AM/FM tuner or whatever, use opera­tional amplifier ICs in their output stages. This is important because it means that the inverse RIAA network can have quite a low impedance and still not upset the performance of the program source. Second, the phono inputs of the amplifier have three re­ quirements if they are to give optimum performance. They must be presented with a source which has the same frequency characteris­ tic as a magnetic phono cartridge and the signal level must be about the same. But most important, the source impedance “seen” by the phono inputs should be as low as possible so that we obtain the optimum signal to noise ratio. If we were to use a high impedance filter and attenuation network, it would give the right overall frequency response and signal levels but the resulting sound quality would be unsatis­factory because the background hiss and noise would be too loud. So we have designed a network which provides a low impedance source for the phono inputs and the result is very low background noise. In fact, when you have the device installed properly, it will be difficult to hear the difference between your regular line inputs (ie, CD, tuner etc) and your converted phono inputs. As you can see from the circuit of Fig.2, the inverse filter network, consisting of a 200kΩ and 16kΩ resistors shunted by capacitors, is virtually identical to the feedback components of the RIAA version of the universal preamplifier published in the April 1994 issue of SILICON CHIP. Surprised? You should not be, since in an RIAA preamplifier the feedback network is an attenuator and filter, exactly what is needed here. We tried several inverse RIAA filters before settling on this one. 0 -10 -20 20 100 HERTZ 1k 10k 20k Fig.1: this graph shows the frequency characteristic of the filter circuit. RIGHT INPUT .015 .0047 200k 16k RIGHT OUTPUT 560  LEFT INPUT .015 .0047 200k 16k LEFT OUTPUT 560  TO AMPLIFIER CASE INVERSE RIAA NETWORK Fig.2: the circuit of the inverse RIAA network is an attenuator & filter which exactly compensates for the magnetic cartridge equalisation in the amplifier. It provides a low impedance source to the phono inputs to ensure low background noise. LEFT INPUT PARTS LIST 1 diecast case to suit PC board 1 PC board, code 01105941, 39 x 46mm 2 2-way RCA socket panels (Jaycar Cat. PS-0263 or equivalent) 1 solder lug 4 6mm untapped spacers Capacitors 2 .015µF MKT polyester 2 .0047µF MKT polyester Resistors (0.25W, 1%) 2 200kΩ 2 560Ω 2 16kΩ Miscellaneous Screws, nuts, lockwashers, hookup wire, solder. .015 .0047 200k 16k LEFT OUTPUT 560  RIGHT INPUT 200k 560  16k .015 .0047 RIGHT OUTPUT Fig.3: the component overlay of the PC board. Note that the shields of the RCA phono sockets are not connected to the case of the device. June 1994  55 This photo shows the internal details of the inverse RIAA network prototype. No shielded cable is required for wiring the RCA sockets since the metal box provides a total shield for the circuit. & November 1993 issues of SILICON CHIP. With the latter control unit, we were able to obtain an overall frequency response from the con­verted phono inputs within ±0.3dB from 20Hz to 20kHz and a signal to noise ratio of 78dB unweighted with respect to 1kHz and 200mV. These are excellent figures. Just how well the inverse RIAA network performs will depend on the quality of the amplifier it is teamed with but as you can see, the results are more than adequate for program sources such as tape decks, VCRs and tuners. For our listening tests, we used a Yamaha CDX-1110 CD player which has two sets of outputs. One set we connected to the CD inputs on the amplifier in the normal way while the other set of outputs were connected via the inverse RIAA network and then to the phono inputs of the amplifier. We were then able to make direct comparisons between the CD LEFT SILICON CHIP and phono inputs. In practice, unless the CD player was in pause mode, it was very difficult to tell the difference. Construction For this project you can go as basic Fig.4: actual size artwork for the PC board. OUTPUT RIGHT GROUND +20 DECIBELS +10 0 -10 -20 20 100 HERTZ 1k 10k 20k INVERSE RIAA FILTER LEFT INPUT RIGHT Fig.5: this the front panel artwork used for our prototype. It shows the inverse RIAA filter characteristic provided by the circuit. 56  Silicon Chip or as deluxe as you want. You could assemble the circuit on a small piece of Vero­board or you could go for the deluxe approach as we did – put it on a small PC board which is then wired in a diecast metal case. Whichever approach you use, the finished circuit must be mounted in a metal case which is earthed back to the amplifier’s case. If this is not done, you will have problems with hum pickup. We wired up our prototype circuit on a small PC board meas­uring 39 x 46mm and coded 01105941. After the six resistors and four capacitors are mounted, the board was mounted in the diecast box. This needs to be drilled for the four RCA phono sockets and four screws to mount the PC board. Finally, a solder lug and wire lead must be fitted to the case for earthing. When installing the unit, keep the unit away from the power transformer in your amplifier and make sure that the input and output leads do not drape across mains power cords otherwise hum pickup may be a problem. Finally, while we optimised the circuit to suit CD player signal levels and typical audio amplifiers, you may need to increase or reduce the signal level to suit your application. This is easily done. If you want more signal level, increase the 560Ω resistors at the output to say, 1kΩ. Alternatively, if you need less signal level, try reducing the 560Ω resistors to 330Ω SC or 270Ω. 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. V+ FROM POWER SUPPLY +V FROM PLUG-PACK 5 1.5k 10 25VW 2 +1.8V LED1 RED 4 IC1a 3 LM324 11 1 6.8k 6 VR1 10k 10T  7 100k G IC1b Q1 IRF740 D 10 S 9 8 100k G IC1c S 10k 0.1 10k 0. 22  10W 0.1 Q2 IRF740 D 0. 22  10W 0.1 0V TO LOAD Variable constant current load This circuit is invaluable when servicing a circuit that keeps blowing fuses. For example, let’s assume that you have to fix a circuit that keeps blowing a fuse rated at 5A. In that case, you simply connect this unit across the fuseholder, set it to 5A and proceed with your service checks. LED 1 is used as a 1.8V reference and is buffered by vol­tage follower IC1a. Its output drives a voltage di- GND OF POWER SUPPLY vider consist­ing of a 6.8kΩ resistor and a 10kΩ 10-turn pot (VR1). VR1 (the current-limit pot) in turn sets a reference voltage of between 0V and 1.1V on pins 5 & 10 of IC1. IC1b & IC1c drive parallel Mos­fets Q1 & Q2 so that the voltage across each 0.22Ω resistor is equal to the voltage on VR1’s wiper (assuming that the supply can deliver the required current). If this voltage is 1.1V, for example, RF actuated CW sidetone unit This unit will allow radio amateurs engaged in Morse Code (CW) communications to monitor their own sending. It is built from readily-available, non-critical components and requires no connections or modifications to the transmitter to function. The sidetone unit’s antenna wire is wrapped around the coaxial line to the antenna to provide a small amount of RF to be rectified into a DC voltage by an OA95 detector diode. This voltage turns on a simple two-transistor switch which supplies voltage to a 555 audio oscillator (IC1) to comfortably drive a small 8-ohm loudspeaker. The 10kΩ resistor sets the tone of the oscillator and can be varied if a different pitch is desired. 58  Silicon Chip then 1.1V appears across each 0.22Ω resistor and so a maximum current of 5A flows through each resistor (10A in total). This can easily be extended to 15A by adding another op amp and Mosfet output stage. Construction is not critical but be sure to provide suffi­cient heatsinking for the two Mosfets. E. Kochnieff, Lutwyche, Qld. ($30) TO ANTENNA COAXIAL CABLE TRANSCEIVER ANTENNA PICK-UP LEAD S1 +9V Q2 BC558 5.6k .01 .01 D1 0A91 Q1 BC548 10k 10k 47k 470uH .001 100k 10k 7 6 4 3 IC1 NE555 2 0.1 0.1 8 33 R 150  100 100 1 8 0V ADJUST VOLUME WITH R Although, this unit was built to suit a 100W transceiver, it can also be used by low-power (QRP) operators if coupling to the feedline is increased sufficiently to allow the sidetone unit to pick up enough RF energy. Peter Parker (VK6BWI), Bentley, WA. ($25) Photographic lightmeter adapter After determining “R” for a photocell as in the Light Meter Adapter described on page 32 of the May 1994 issue, it is easy to construct a photographic lightmeter to read shutter speed direct­ly for any aperture between f1.4 and f45. The f number series in modern cameras is 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32 & 45. Each successive f number reduces the light on the film by a factor of two compared to the previous f number. This circuit uses an 11-position switch to load the cell with “R” at f45, 2R at f32, 4R at f22, and so on up to 1024R at f1.4; ie, the value of the load resistor doubles at each succes­ sive step. In use, the photocell is simply aimed towards the subject to be photographed and the switch position varied until a reading is obtained on the 200mV scale of a digital multimeter. For example, if the switch is at f11 and the meter reads 60, the correct exposure for 100 ASA film will be obtained at f11 and 1/60th of a second shutter speed. Note that the meter reads shutter speeds of between 1 second and 1/200th of a second. You can calculate higher speeds by doubling the speed for each step down in the f number. In the above example, we had f11 and 1/60th of a second. If you now select f8, the meter will read 120 but if you then Discrete monostable multivibrator These days, you’d be hard pressed to find a monostable circuit that didn’t use a 555 timer. However, if you don’t happen to have one handy, you could give this circuit a whirl. It’s by no means original and uses common parts which you should have lying around in your junkbox. Transistors Q1 and Q2 are connected up in the classic style with bases cross-coupled – Q1’s via a 100kΩ resistor to Q2’s collector and Q2’s via a 100µF capacitor to Q1’s collector. When the anode of diode D1 is taken low, Q2 is forced off, allowing Q1 select f5.6, the meter reading will overflow. However, you calculate the correct speed as 1/240th of a second simply by doubling the previous number. If you further select f4, then the correct speed is 1/480th of a second. If you have loaded the camera with 200 ASA (or ISO) film, you can use a movable scale D1 or move the indicator knob on BPW21 the switch. I switch the knob to the f1.4 position, unscrew the knob without shifting the switch position, and then fix the knob to read f2. Similarly, for 400 ASA (ISO) film, I fix the knob on f2.8. By adding a dome diffuser, the instrument becomes an incid­ent light meter, where­by you go to the subject position, direct the instrument towards the camera and read the exposure required. This is very useful with backlighting or side­lighting. It is also useful if the background is predominantly too dark or too light (say too much sky is included in the picture). These situations can fool an on-camera meter. You can salvage an incident light dome from a defunct lightmeter or you can make one from half a ping-pong (table tennis) ball. The diffuser needs to be dome shaped so as to integrate the light in an approximate hemisphere and it needs to attenuate the light from a nearly parallel beam by a factor of seven. f1.4 512R 256R 128R 64R 32R  16R 8R 4R 2R R f2 f2.8 f4 f5.6 f8 f11 TO DIGITAL MULTIMETER 200mV RANGE f16 f22 f32 f45 R Unfortunately, a ping-pong ball only attenuates by a factor of about four. This can be corrected by adding small Indian-ink dots spaced reasonably uniformly (about 9mm apart) to the inside of the dome. When you have finished, check the attenuation and increase the size of the dots as required. Note that you must cover the whole surface that light from any direction is attenu­ ated by close to the same amount. The resulting meter is easy to use and the results compare favourably with a professional lightmeter. Victor Erdstein, Highett, Vic. ($20) to be turned on via the 2.2kΩ and +12V 100kΩ resistors. LED1 LED1  Because the 100µF capaciR 2.2k 680k tor can’t change its voltage in­ C 680  stantaneously, the positive side 100 100k goes from 12V to 0.7V and so the OUTPUT OUTPUT 16VW negative side goes from 0.7V to Q2 Q1 BC548 -10.6V. This holds Q2 off and Q1 BC548 D1 and the LED on while the 100µF 1N914 capacitor discharges via the 680kΩ resistor. Once the voltage at this TIME = 0.638RC junction hits 0.6V, Q2 turns on INPUT and Q1 turns off again, turning output while the monostable is LED 1 off also. The time (T) of the pulse at the triggered, you can take it from the collector of Q1 is as follows: T = collector of Q2. Darren Yates, 0.638RC. Note also that this output is an active low. If you need a high SILICON CHIP. June 1994  59 MISCELLANEOUS ITEMS COMPONENTS AND KITS We have large quantities of many of the following and can offer higher quantity discounts. IEC EXTENSION LEADS: with moulded IEC plug and socket, 2 metres long .$5 HIGH INTENSITY LEDs: 550-1000mCd at 20mA, 5mm diameter 10 for ......... $4 IR DIODES: 16mW O/P <at> 100mA, 880 or 940nm 10 for ................................ $5 IR DETECTOR: very fast rectangular PIN diode 10 for .................................... $10 TRIACS: 60A - 600V stud-mounted THOMPSON type TGAL606 .................... $8 PIR DETECTOR: dual element detector plus Fresnel lens only, typical movement detector cct. supplied ...................................................................... $10 ULTRASONIC TRANSDUCERS: Murata (Japanese), 40KHz Tx - Rx pair ...... $3 MICROPHONE INSERTS: Standard Electret Omnidirectional insert .......................................................... $1 Miniature Electret Omnidirectional insert .......................................................... $1.80 Unidirectional Electret insert ............................................................................. $6 Unidirectional Dynamic insert ........................................................................... $7 HIGH VOLTAGE DIODES: 8kV 3mA ........................................................................................................... $1.20 10kV 20mA ....................................................................................................... $1.80 HIGH VOLTAGE DISC CERAMICS: 0.01uF 3kV ....................................................................................................... $1.20 0.01uF 5kV ....................................................................................................... $1.80 1000pF 15kV .................................................................................................... $5 470uF 380V Electros as used in TVs (rectified mains) ..................................... $3.50 ELECTRIC FENCE KIT: PCB and comonents ................................................. $40 GARAGE DOOR/GATE REMOTE CONTROL KIT: Tx $18 Rx $79 LASER BEAM COMMUNICATOR KIT: Tx, Rx, plus IR Laser ...........................$55 PLASMA BALL KIT: PCB and components kit, needs any bulb ........................$25 ENCODER - DECODER ICs: AX527’s, AX528’s, AX526’s. All one price, .... $4 Ea. OP27: super operational amplifier IC at below 1/2 price .............................. $4 Ea. LARGE DC MOTOR - GENERATOR Large Matshushita permanent magnet DC motors that were removed from brand new equipment and are rated for 20V operation. We found them to be very powerful when powered from a 6-20V DC supply. No load current <at> 12V is 200mA. Weight 0.7kg, 75mm dia­meter, 90mm long, have a 5mm dia. fluted shaft which is 14mm long, have sealed ball bearings. Also have a separate tachometer circuit built in, which produces 50 pulses per revolution when powered from a 5V supply. Connecting up information provided. These motors can also double up as a generators as they produce a DC output when rotated. Can be used for powering a small vehicle, experimentation with wind powered systems etc. Item No. 0216NS $18 transformer (125 x 80 x 40mm, 1.8kg), plus a totally self-contained matching switched mode regulated power supply (165 x 55 x 90mm, 0.4kg). Intercon­ necting leads and plugs/sockets and information is provided. Regulated DC outputs: +24V/2A, +12V/0.5A, +5V/0.5A, and -12V/50mA. We do not have the full specifications on these two matching units, that were removed from BRAND NEW laser printers but have tested the transformer with a 100W load. We have a LIMITED but good quantity of these supplies and are selling them for far less than the value of the transformer itself. $28 For the 240 - 30V transformer, the matching switched mode supply, the interconnecting leads with matching plugs and sockets & information. Item No. 0215NS. DC FANS IC-controlled ball bearing type. These 24V 110mA 3-inch Japanese-made DC fans work well from 5-24V. They also move a good amount of air whilst drawing 60mA from a 12V battery. Can be powered directly from one of our 6V solar panels ($10). Apart from the usual uses, this one can be used for expelling hot air from vehicles, etc. Item No. 0217NS $8 12A SOLID STATE RELAYS Removed from BRAND NEW equipment. These approved isolated Mitsubishi 240V 12A solid state relays (Type SF120DPS H1 - 4) need a few ma from a 4-7V (even higher if a resistor is added) DC source to operate. Great for switching mains appliances from logic circuitry. Screw connections provided, overall dimen­sions 41 x 47 x 20mm. Available at about 1/4 of their real value. Item No. 0218NS. $14 SWITCHED MODE POWER SUPPLIES WITH ISOLATION TRANSFORMER Very modern low profile 240V - 30V AC 60  Silicon Chip MAINS CONTACTOR RELAY Approved mains contactor that has a 24V 250-ohm relay coil and four separate SPST switch outputs. Two of the output contacts are rated at 20A and the other two at 10A. Removed from new equipment, approved Omron brand, connection is by spade connec­tors (provided ), mounting bracket provided. Relay body dimen­sions: 60 x 60 x 35mm. ITEM No. 0219NS. $8 CIRCUIT BREAKERS Small chassis mount 3.15A circuit breakers (30 x 18 x 10mm) with reset push button. Up to 125V AC or DC operation, mounting screws and spade connectors provided. Approved Hosiden brand (Japanese), removed from new equipment. Inexpensive additional protection on all your supplies. Item No. 0220NS. $2 MAINS FILTERS These 240V 8A mains filters were made by Tokin in Japan. They were removed from new equippment, are in a cylindrical metal case, provided with a mounting screw/nut and spade connectors. Diameter 44mm, 40mm long. The internal circuit of this filter includes two 1.5mH inductors, two 0.47uF capacitors, two 4700pF capacitors and one 470Kohm resistor. We also provide a surge suppressing varistor with each filter. Good but LIMITED STOCK.Item No. 0221NS. $9 EHT POWER SUPPLY These EHT power supplies were designed to deliver -600V, -7.5kV and +7kV in a laser printer, whilst powered from a 24V 800mA DC supply. They were removed from brand new equipment and are contained in a plastic case with overall dimensions of 100 x 85 x 80mm. The electronics inside these supplies actually con­tains three seperate supplies on two seperate PCBs. The output connections are easy to access and a prewired input power connec­tor is also provided: Connecting up information is provided. Great for experienced experimenters. BARGAIN PRICED. Item No. 0222NS. $16 STEPPER MOTOR DRIVER KIT SPECIAL This kit will drive two stepper motors: 4, 5, 6 or 8 eight wire stepper motors from an IBM computer parallel port. A seper­ate power supply is required to run the motors. A detailed manual on the COMPUTER CONTROL OF MOTORS plus circuit diagrams / de­scriptions are provided. Note that no stepper motors are provided with this kit. We also provide the necessary software on a 5.25-inch disc. Great “low cost” educational kit. $35 THE SPECIAL?? We will include one of our $14 (5V, 6-wire, 7.5 deg.) stepper motors FREE with this kit! IR LASER DIODE SURPLUS SPECIAL We have a good supply of some BRAND NEW 780nM LASER DIODES (barely visible) which are mounted in a professional adjustable collimator-heatsink assembly. With each of these assemblies, we will also supply a CONSTANT CURRENT DRIVER kit and a suitable PIN DIODE that can serve as a detector, plus some INSTRUCTIONS. Suitable for medical use, perimeter protection, data transmis­ sion, IR illumination, etc. Exerimenters delight at a SPECIAL PRICE. Item No. 0223NS. $28 SUPER MAGNETS We have added two RARE EARTH magnets to our range and re­duced their price. Very powerful - you will not be able to sepa­rate two of these by pulling them apart directly away from each other and you should be careful when handling these! Some claims were made on recent TV shows regarding the usage of powerful magnets like these in medical applications. Cylindrical 7 x 3mm $2, Item No. 0224A; cylindrical 10 x 3mm $4, Item No. 0224B; Toroidal 35mm inner 7mm thick, $9.50, Item No. 0224C. 3mW VISIBLE LASER DIODE SPECIAL We have bought a surplus quantity of some BRAND NEW Toshiba TOLD9200 3mW-670nM visible laser diodes and are offering a kit that includes one of these diodes, plus an APC driver kit, plus a collimating lens - heatsink assembly. That’s a complete 3mW collimated laser diode kit for a RIDICULOUS TOTAL PRICE OF: $45 Item No. 0164B BIGGER LASER We have a good but LIMITED QUANTITY of some brand new red 3mW+ tubes and some “as new” red 6mW+ laser heads that were removed from new equipment. Tube dimensions (3mW+): 35mm diameter by 190mm long, Head dimensions: 45mm diameter by 380mm long. With each of the lasers we will include our 12V Universal Laser power supply. BARGAIN AT: $110 3mW+ tube/supply, Item No. 0225A $170 6mW+ head/supply, Item No. 0225B 12V - 2.5 WATT SOLAR PANELS These US made amophorous glass solar panels only need termi­nating and weather proofing. We provide terminating clips and a slightly larger sheet of glass. The terminated panel is glued to the backing glass, around the edges only. To make the final weatherproof panel look very attractive some inexpensive plastic “L” angle could also be glued to the edges with some silicone. Very easy to make. Dimensions: 305 x 228mm, Vo-c: 18-20V, Is-c: 250mA. BARGAIN PRICED: $25 ea. or 4 for $80, Item No. 0226 Each panel is provided with a sheet of backing glass, termi­natig clips, an isolating diode, and the instructions. Higher quantity discounts apply on this item: Ring. CCD CAMERA Monochrome CCD camera which is totally assempled on a small PCB and includes an auto iris lens. It can work with illumination of as little as 0.1 lux and it is IR responsive. Can be used in total darkness with infrared illumination. Overall dimensions of camera are 24 x 46 x 70mm and it weighs less than 40 grams! Can be connected to any standard monitor or the video input on a video cassette recorder. $239 Item No. 0227 IR “TANK SET” ON SPECIAL is a set of components that can be used to make a a very responsive infrared night viewer. The matching lens tube and eyepiece sets were removed from working military quality tank viewers. We also supply a very small EHT power supply kit that enables the tube to be operated from a small 9V battery. The tube emloyed is probably the most sensitive IR responsive tube we ever supplied. The resultant viewer requires low level IR illumina­tion. Basic instructions provided. Item No. 0228UTS $120 For the tube, lens, eyepiece and the power supply kit. When ordering specify preference for a wide angle, or a telescopic objective lens. CAR ALARM We have purchsed a good but limited quantity of this well known brand Australian made car alarm. It has been made obsolete because it doesn’t feature UHF remote control. But look at the features! Voltage drop detection (wired directly or internal), pin switch detection for bonnet/ boot, piezoelectric vibration detector, optional passive arming via ignition switch, ignition disable via master switch if passive arming is not used, may be wired to existing door pin switches to act as a switch - sensing last door arming alarm, 30 second exit delay, 7 second entry delay, flashing LED - intrusion indicator provided, flashes vehicle indicators when alarm is sounding, extra negative output to power second siren or pager, colour coded wiring siren provid­ed, powerful 40 watt 125 dB siren which employs a dynamic speaker (a sound that makes most car alarm sirens sound like toys)!! Priced at about 1/3 of their original price. Item No. 0229. $40 The entry/exit times are easy to change and the unit is easy to modify for UHF remote - hidden magnetic reed switch ON - OFF control, as the main control IC has a toggle input. Some informa­tion included. FIBRE OPTIC TUBES These US made tubes are used but in excellent condition. Have 25/40mm diameter fibre optically couled input and outut windows. The 25mm tube has an overall diameter of 57mm and and is 60mm long; the 40mm tube has an overall diameter of 80mm and is 92mm long. The gain of these is such that they would produce a good image in aproximately 1/2 moon illumination, when used with a suitable “fast” lens, but they can also be IR assisted to see in total darkness. The superior resolution of these tubes would make them suitable for low light video preamplifiers, wild life observation, and astronomical use. Each of the tubes is suplied with an 9V - EHT power supply kit. INCREDIBLE PRICES: $120 for 25mm tube plus supply. Item No. 0230A $190 for 40mm tube plus supply. Item No. 0230B Three of these tubes can be cascaded to make a very high gain image intensifier! We should have a kit and instructions available to make these. Approximately $270 for 25mm kit and $450 for the three stage kit. We will also have available some made up three stage tubes. SOLID STATE “PELTIER EFFECT” COOLER - HEATER These are the major parts needed to make a solid state ther­moelectric cooler - heater. We can provide a large 12V 4.5A Peltier effect semiconductor, two thermal cutout switches and a 12V DC fan for a total price of.: $45 Item No. 0231 We include a basic diagram - circuit showing how to make a small refrigerator - heater. The major additional items required will be an insulated container such as an old “Esky”, two heat­sinks and a small block of aluminium. IMAGE INTENSIFIER TUBE & SUPPLY These are the key components needed for making a PASSIVE NIGHT VIEWER. The small prefocussed Russian image intensifier tube only requires a low current EHT power supply to make it operational, which we provide in kit form. Draws 20mA from a small 9V battery. With a suitable low light objective lens (not provided) the resultant viewer will produce useful pictures in sub-moonlight illumination and it can also be IR assisted. IN­CREDIBLE PRICE: $150 Item No. 0232A For the Russian image intensifier tube and an EHT power supply kit! All that is needed to make a complete passive night viewer is a lens, an eyepiece, a 9V battery, a case and a switch. We can supply a matching lens and eyepiece at $68 for the pair: Item No. 0232B. 4-CHANNEL UHF REMOTE CONTROL KIT E.A. March 1994. Features a 3-channel transmitter which is small enough to fit onto a key ring. The fourth channel can be accessed by a second transmitter. For example, each of the two transmit­ters could have two common channels and one individual channel. The compact reciever emloys a ready made and pre- aligned (304MHz) UHF receiver “front end” module. Over 100 metres range, has 12A SPDT relay contact outputs, has a user-programmable security code with 6561 combinations, easy to construct, is expandible, etc. Transmitter: $18. Receiver: $62. TWO TRANSMITTERS AND ONE RECIEV­ER: $96 Cat. No. GK150 BUDGET LASER A vey economical laser tube - 12V laser supply combination. The 12V swiched mode power supply kit provides the tube with a constant current and will work from 10-15V. Draws 0.5A at 12V: very efficient! The tube supplied is used, tested and guaranteed, 632.8nm (red), power output 0.5-1mW. The tube/power supply kit combination for a total price of only: $49 Item No. 0233 FM TRANSMITTER KIT - MKII This low cost FM transmitter features pre-emphasis and high audio sensitivity as it can easily pick up normal conversation in a large room, a range of well over 100 metres, etc. It also has excellent frequency stability. Specifications: Tuning range: 88-108MHz; Supply voltage: 6-12V; Current consumption <at> 9V: 3.5mA; Pre-emphasis: 75us; Frequency response: 40Hz to greater than 15KHz; S/N ratio: greater than 60dB; Sensitivity for full devia­tion: 20mV; Frequency stability with extreme antenna movements: 0.03%; PCB dimensions: 25 x 43mm. Construction is easy and no coil winding is necessary. The coil is preassembled in a shielded metal can. The double sided, solder masked and screened PCB also makes for easy construction. The kit includes a PCB and all the on-board components, an electret microphone, and a 9V battery clip. Cat No. GK 139. $11 Ea. or 3 for $30 FM TRANSMITTER MK1 KIT This unit has most of the features of our FMTXMK2 transmit­ter but is much, much smaller. The complete transmitter PCB (miniature microphone included) is the size of an “AA” battery and it is powered by a single “AA” battery. We use a two “AA” battery holder (provided) for the case and a battery clip (short­ed) for the switch. Estimated battery life is over 500 hours!! SAME PRICE AS OUR FMTXMK2: $11 Ea. or 3 for $30. Cat No. GK138. MASTHEAD AMPLIFIER KIT Based on an IC with 20dB of gain, a bandwidth of 2GHz and a noise figure of 2.8dB, this amplifier kit outperforms most other similar ICs and is priced at a fraction of their cost. The cost of the complete kit of parts for the masthead amplifier PCB and components and the power and signal combiner PCB and components is AN INCREDIBLE: $18 Cat. No. GK136 For more information, see a novel and extremely popular antenna design which employs this amplifier: MIRACLE TV ANTENNA - EA May 1992. Box, balun and wire for this antenna: $5 extra. HARD DISC DRIVES These are BRAND NEW 10Mb PC HARD DISC DRIVES. Originally made by Seagate Technology. Sure their capacity is not up to modern standards but look at the price! 306 cyl, 4heads, 17 sectors, MFM type. Overall dimensions: 148 x 85 x 208mm. Limited quantity: $39 Item No. 0234 INDUCTIVE PROXIMITY SWITCHES These industrial quality detectors will detect ferrous and non-ferrous metals at close proximity. Some are DC powered (10-30V), some are mains AC powered, and all will switch loads di­rectly. All have three wires for connecting into circuitry: two for the supply and one for switching the load. These also make excellent sensors for rotating shafts, etc. LIMITED SUPPLIES. ON SPECIAL AT: $22 Ea. or 6 for $100. Item No. 0192 16 x 2 DISLAYS These industrial quality, high temperature, 16 x 2 character displays are easy to drive (ASCII). Dimensions: 80 x 45 x 10mm, character size 4.8mm, +5V supply. Also require a low current negative voltage supply (5-10V ) and an external trimpot for contrast control. $25 Ea. or 5 for $100. Item No. 0131 CCD SCANNER CARD These CCD scanner cards were made by NEC for high resolution line scanning applications. They feature a 4096 element single line CCD which is centrally located on the PCB. Information and circuit provided. $ 65 Item No. 0235 OATLEY ELECTRONICS PO Box 89, Oatley, NSW 2223 Phone (02) 579 4985. Fax (02) 570 7910 Major cards accepted with phone & fax orders. P & P for most mixed orders: Aust. $6; NZ (airmail) $10. June 1994  61 This simple circuit uses your PC’s games card to monitor & display the rate of charge or discharge of a nicad battery pack. It can be built in just a few minutes & requires only the addition of a low-cost software package to make it work. By DARREN YATES A PC-based nicad battery monitor This project is a logical follow-on from our “Experiments With Your Games Card” series in the Computer Bits column. It will allow you to monitor 7.2V nicad battery packs during their charge and discharge cycles, so that you can see how they are progress­ing. What’s more, it can be easily modified to handle 6V, 9.6V or 12V cam­corder batteries, which have become notorious for memory effects. By using some simple software, the project will give an analysis of your battery over time and indicates whether you have a problem with ei- ther memory effect, incorrect charging or exces­sive discharging. In addition, you can save the readings to disc and then pull them out for later analysis and comparison. And if you have a graphics printer, you can also do a print screen to the Clipboard and then paste the image into Paintbrush (and then print out from there), provided you have Windows running in the background. This will also allow you to save the image as a bitmap (.BMP) file and then import it into just about any Windows-based program, just as we have done here to illustrate this article. Games card interface Fig.1: the input control circuitry for a typical games card. There are four such circuits to cover all the controls on a joystick. 62  Silicon Chip By utilising the games card which appears in just about every PC sold these days, we can do away with just about all of the usual circuitry that would otherwise be required. As a re­ sult, our circuit consists of just three resistors and that’s about all. As mentioned in previous issues, the games card has two analog inputs which are used by the joystick’s X- and R1 2.2k 7.2V NICAD BATTERY R2 4.7k 56k PIN 3 GAME CARD CONNECTOR PIN4 NICAD BATTERY MONITOR FOR PCS Fig.2: the circuit uses just three resistors. Note that R1 & R2 must be adjusted to suit the nominal battery voltage – see Table 1. Y-axis controls – see Fig.1. These are just 100-500kΩ pots which vary the charging current to a 0.01µF capacitor on the games card PC board. A software counter keeps tabs on how long it takes for the monostable controlled by the joystick to reset and this number is available to any software. In our case, we can replace the variable pot inside the joystick with a variable voltage (ie, the nicad battery voltage). The reason this works is that in a normal joystick arrangement, a fixed voltage (ie, the 5V rail) and a variable resistor provide the variable current. In our case, the variable current is pro­vided using a variable voltage (the battery under test) and a fixed resistor. So, in the end, we wind up with pretty much the same thing. We simply add the battery to the our three resistor circuit and the PC does the rest via our purpose-designed software pack­age, GAMESBVM.BAS/EXE. Circuit diagram The project is built using the Games Breakout Board de­scribed in the Computer Bits column for April 1994. Fig.3 shows the parts layout for that board, while Fig.4 shows the full size board pattern. However, there is no reason why you could not use your own board pattern if you wish, provided you make all the right connections. TABLE 1 The battery voltage is plotted on screen as a continuous graph which can then be saved & reloaded at a later date. In this case, 500 samples were taken at 0.5-second intervals but this time period can be varied to suit the application. 4.7k Games breakout board This “screen-grab” shows the opening menu that appears when the software is booted up. It offers six choices: (1) set the nominal voltage; (2) set the time between measure­ments; (3) take readings; (4) save readings to file; (5) load and display readings from file; and (6) quit. 56k Vbatt R1 R2 4.8V - - 6V 1k 4.7k 7.2V 2.2k 4.7k 9.6V 4.3k 4.7k 12V 6.8k 4.7k 7.2V NICAD BATTERY 2.2k Let’s now take a quick look at the circuit diagram – see Fig.2. As shown, the battery under test is connected to the circuit and the voltage tapped off by a 2.2kΩ and 4.7kΩ resistive divider. The resulting output is then fed to pin 3 of the games card via a 56kΩ current-limiting resistor, while the common ground connection is made via pin 4. And that’s all there is to it! The voltage divider is set so that the tapoff point gives close to 5V when the battery is at its nominal output voltage (ie, 7.2V). In fact, if you go through the maths, you will find that a 7.2V nicad pack will give 4.9V at the tapoff point. For other battery voltages, we simply adjust the value of the divider to ensure a 5V output (the 56kΩ current limiting resistor remains the same in all cases). Table 1 shows the de­tails. Note that if you have a 4.8V nicad pack, then you only need the 56kΩ current-limiting resistor. Fig.3: the prototype was built onto the Games Breakout Board described in the April 1994 issue. You could also connect the parts directly to the back of the DB15 socket but make sure that all the connections are correct. June 1994  63 PARTS LIST 1 PC board, code 07103941, 95 x 59mm 1 DB15 female PCB-mount socket 1 GAMESBVM software disc Resistors (0.25W, 1%) 1 56kΩ 1 4.7kΩ 1 2.2kΩ GAMESBVM SOFTWARE Fig.5: this is the full-size etching pattern for the PC board. Alternatively, you could even connect the resistor network directly to the back of the DB15 socket. Be very careful if you do this though. If you make a wrong connection or short any of the pins, you could damage the games card. Before you start construction, make sure that the board pattern is correct and that there are no shorts or breaks in any of the tracks. Once you’re satisfied that the board is OK, in­stall the four wire links and the three resistors. After that, it’s simply a matter of installing the DB15 PC-mount socket and adding the test leads for the battery. DB15 cable If you’re lazy, you can buy a DB15DB15 male-male cable for around $30. This will be invaluable if you have other devices to connect to the games card, since all 15 pins are connected, but it’s expensive overkill if used solely for this project. In this circuit, because you only need two connections to the games card, you can easily “roll your own” cable but make sure that the connections are correct. Software As you will have probably suspected with such a simple circuit, most of the work is done by the PC through software. The program is too large for us to publish here but readers can obtain the source code (GAMES­BVM. BAS), the object code (GAME­SBVM. OBJ) and the complied, executable program (GAMES­BVM.EXE) on either a 5.25-inch or 3.5-inch disc directly from SILICON CHIP. The nominal battery voltage is entered in at this screen prompt. This voltage must be 4.8V or greater & the circuit must be adjusted for values other than 7.2V. 64  Silicon Chip The complete GAMESBVM software package is available from SILICON CHIP for $7 + $3 p&p. Please specify either a 5.25-inch or 3.5-inch disc. Send your cheque/ money order to: Silicon Chip, PO Box 139, Collaroy, NSW 2097; or phone in with your credit card details (Visa, MasterCard and Bankcard) on (02) 979 5644; or fax your order to (02) 979 6503 (see the order coupon in this issue). The software was written in Quick­ BASIC 4.5 but should also work quite happily with DOS 5/6’s QBasic should you wish to modify it in any way. The opening menu of the software offers six choices: (1) set the nominal voltage; (2) set the time between measure­ments; (3) take readings; (4) save readings to file; (5) load and display readings from file; and (6) quit. The readings are stored on file in ASCII format so that you can use them in other programs or even modify them if you so wish. The screen grabs in this article give an idea of what to expect as you go through the various stages of the soft­ware package. Note that measurements are displayed on the screen as they are taken but once the voltage falls below 10% of the bottom scale, then the program automatically stops and returns to the main menu. When saving the measurements, you can use the standard drive:\ path\filename.ext format to store them where you wish. By using the Nicad Battery Monitor for PCs, you will be able to keep tabs on just what the battery pack is doing. It should also show up any early signs of “memory effect”, thereby allowing you to take the appropriate counterSC measures before it goes too far. COMPUTER BITS BY DARREN YATES BIOS interrupts: your computer’s nuts & bolts This month, we continue our discussion on BIOS routines & look at how you can gain access to them using QBasic & QuickBA­SIC 4.5. In this article, we take a look at the keyboard routines & see how you can check the keyboard status. The built-in operating system (BIOS) is the most basic level at which structured routines can be accessed and used by your computer. They handle everything from keyboard input to disc drives to video displays and updating the real-time clock. By using these routines, you can gain access to areas of your machine that are not easily done through normal programming methods and you can perform new tasks that are not found in standard languages. Most computer programs you buy these days all use combina­tions of key strokes in order for some function to take place. Windows is a perfect example. To get the FILE menu to appear, you have to press the ALT key down and then “F”. QBasic and QuickBA­SIC both use this type of key function in their integrated devel­ opment environments. Other keys However, the BIOS can actually go quite a bit further than that by allowing you to check the following keys: • right SHIFT key • left SHIFT key • CONTROL key • ALT key • INSERT key • NUM LOCK key • SCROLL LOCK key • CAPS LOCK key BIOS Interrupt 16H, service 02H is designated READ KEYBOARD SHIFT TABLE 1: AX Register On Return From INT 16 Service 02H Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 x Insert key on x Caps Lock on x Num Lock x Scroll Lock x Alt key pressed x Control key pressed x Left shift key pressed x 66  Silicon Chip Right shift key pressed STATUS and returns an 8-bit code, each bit representing the setting of one of the above keys. This is shown in detail in Table 1. As you can see, the most significant bit represents the INSERT key, bit 6 the CAPS LOCK key and so on. Note that a “1” for each bit means that the key is either down or locked on. Note also that it’s possible to distinguish between the right and left shift keys which is not normally achievable in most languages. QuickBASIC is not very good at allowing programmers to check for multiple keys down and all of the routines provided only allow you to check for one key at a time. However, the people at Microsoft did at least give us the ability to access the interrupts through the CALL INTERRUPT() subroutine. Unfortunately, CALL INTERRUPT() didn’t make it into QBASIC either so we’ve used the generic CALL ABSOLUTE() to perform the same task. Keyboard.bas The program elsewhere in this column, KEYBOARD.BAS, uses CALL ABSOLUTE(), QuickBASIC’s assembly language link, to access the BIOS interrupt 16H and will give you an idea of how to use this program to add to your own programs. Wherever possible, we have included remarks to give you a clearer picture of what is going on. As with other programs that we have presented over recent times, the assembly code is placed into DATA statements and then read into an integer array called ASMPROGRAM. Each data line contains one instruction which is listed next to it in the re­marks. The &H indicates that the hexadecimal code is being en­tered which is automatically converted across to decimal. Let’s just pause for a moment and take a look at the assem­bly code. The first line – PUSH BP – pushes the base pointer onto the stack. The BP register is a secondary stack pointer which is used to access data on the stack relative to a given location. We are simply storing the current value while we muck around elsewhere. The next line – MOV BP,SP – is short for “MOVe the value of the stack pointer(SP) into the base pointer (BP)”. This makes the base pointer look at the area where our assembly program is. After that comes MOV AH,02H which places the hex number 02 into the register AH. Remember that there are four general pur­pose registers in the 8086 – AX to DX – each of which can be referenced by the high or low 8-bits; ie, AH and AL, BH and BL and so on. Loading 02 into AH forewarns the program that we are requesting service 2 of the following interrupt. That interrupt is performed upon the instruction INT 16H. Once completed, the keyboard status bits are returned in the lower 8-bits of AX; ie, in half-register AL. The next line uses some indirect addressing – the most powerful addressing mode the 8086 has – and moves the contents of the base pointer + 6 into register BX. This is where some newcom­ers can get a bit stuck. It doesn’t store the value of the “base pointer + 6” into BX but rather the contents of the base pointer + 6 from the stack into BX. MOV [BX],AX tells the computer to store the current cont­ents of the AX register into the memory address pointed to by register BX. Remember that AX contains our keyboard info in its lower 8 bits. Again, this is another bit of indirect addressing. POP BP returns the stored value of BP back from the stack to restore the original base pointer, ready to go back to the BASIC program and RET 2 returns us to the BASIC program. The “2” tells the machine to adjust the stack pointer to account for the integer variable X (all integer variables are two bytes wide). Once the code is entered into the array, the segment and offset address of the first element in the array must be found. This is so that we can tell the CALL ABSOLUTE() routine where the assembly language routine begins. This is done by the VARSEG and VARPTR commands. VARSEG finds the segment address of the array while VARPTR finds the offset address. You’ll notice that the current segment is transferred to the segment address of the array in the one line: DEF SEG = VARSEG(ASM­ PROG­RAM(1)). The CALL command is then made with the offset address of the first element of the array as well as the return variable X as the two arguments. Upon return, variable X contains the 8-bit information in decimal code; ie, if the INSERT key is on, X will contain 128. If the ALT key is down as well, the code will be 136 (128 + 8). Each bit is then just stripped from the variable and then the appro­priate action taken. AND statement Using the AND statement is exactly like using normal digital logic gates but it is one that often gives new program­ mers a good deal of trouble. As an example, let’s take a look at the theoretical line: VALUE = 112 AND 64 June 1994  67 Basic Listing For Keyboard Utility ‘ Keyboard Shift Status Utility ‘ Copyright 1994 Darren Yates B.Sc. ‘ for Silicon Chip Publications Pty Ltd DEFINT A-Z DIM asmprogram(1 TO 20) position(0) = 5 position(1) = 15 position(2) = 27 position(3) = 38 position(4) = 47 position(5) = 54 position(6) = 62 position(7) = 71 DATA &h55 DATA &h89,&he5 DATA &hb4,&h02 DATA &hcd,&h16 DATA &h8b,&h5e,&h06 DATA &h89,&h07 DATA &h5d DATA &hca,&h02,&h00 : ‘ PUSH BP : ‘ MOV BP,SP : ‘ MOV AH,02h : ‘ INT 16h : ‘ MOV BX,[BP+6] : ‘ MOV [BX],AX : ‘ POP BP : ‘ RET 2 start = VARPTR(asmprogram(1)) DEF SEG = VARSEG(asmprogram(1)) FOR byte = 0 TO 16 - 1   READ newbyte    POKE start + byte, newbyte NEXT byte CLS LOCATE 1, 1: PRINT “Keyboard SHIFT status utlity” LOCATE 2, 1: PRINT “Copyright 1994 Darren Yates B.Sc.” DO WHILE UCASE$(an$) <> “Q” DEF SEG = VARSEG(asmprogram(1)) CALL absolute(x, VARPTR(asmprogram(1))) DEF SEG LOCATE 4, 1: PRINT “ <Insert> <Caps lock> <Num Lock> <Scrl Lock> <Alt> <Ctrl> <L Shft> <R Shft> “ FOR bit = 7 TO 0 STEP -1 IF x AND (2 ^ bit) THEN    LOCATE 5, position(7 - bit): COLOR 15, 1: PRINT “ON “ ELSE    LOCATE 5, position(7 - bit): COLOR 7, 8: PRINT “OFF” END IF NEXT bit COLOR 7, 8 LOCATE 7, 1: PRINT “ Press <Q> to quit. . .” an$ = INKEY$ LOOP END 68  Silicon Chip Now we can assume that we are dealing with two 8-bit numbers since both are less than 256. If we look at the number 112 in binary notation, this works out to be 01110000. The number 64 becomes 01000000. Now just as you would expect in digital electronics, the AND function in BASIC works the same way; ie, each bit is high only if both corresponding bits of the two operands are high. Doing some simple maths: 01110000 01000000+ 01000000 Hence, the answer returned to variable VALUE is 64. The AND function is therefore ideal for checking if a particular bit is set or cleared. Getting back to KEYBOARD.BAS, once the CALL subroutine has been completed, the segment address has to be returned to BASIC’s current modus operandi so that the BASIC section of the program can continue. All of this is performed inside a DO..LOOP loop so that a continuous check can been made on the keyboard until such time as the “Q” key has been pressed. Now each bit is checked inside a FOR..NEXT loop and although it may not be immediately apparent, each run of the loop corresponds to one of the eight bits in variable X. By ANDing the variable with 2 raised to the power of the current loop pointer, we can check each bit from the most significant bit (bit 7) down to bit 0. BASIC has no trouble converting between hex, decimal and binary code and each one is used where appropriate to make understanding the program easier. Now if the particular bit which the FOR..NEXT loop is looking at is set, then the program prints the word “ON” at the appropriate position on the screen underneath that particular key function. We could have used a stack of IF..THEN statements or the CASE SELECT statement or any number of alternatives but we think this is the most compact. As well as that, the program is also quite quick as you would expect when running machine code. The array POSITION holds the correct tab points so that after each bit is checked the right response can be printed in the correct position. This also saves us having to have separate PRINT statements for each bit. Since the POSITION array only has seven elements, we don’t need to dimension it, which saves us another program line. This program will work on all versions of QBasic as well as QuickBASIC versions 4 and up. You can try it also on anything from an XT to a Pentium and you shouldn’t have any problems as the CALL ABSOLUTE() command can only handle 8086/88 mnemonics. Next month, we look at another BIOS interrupt which will enable you to speed up some Windows SC operations. Where To Buy The Software We can supply copies of both KEYBOARD.BAS and a compiled version, KEYBOARD.EXE, on either a 5.25-inch or 3.5-inch disc for $7 plus $3 postage and packaging. You can send in a cheque/money order to SILICON CHIP, PO Box 139, Collaroy, NSW 2097; or phone in your credit card details on (02) 979 5644. Visual BASIC 3.0: the new standard? Visual BASIC has taken the world by storm & is fast becoming the programming standard for creating Microsoft Windows packages. We have taken a look at the latest version & can state that it really works well. By DARREN YATES Question: what computer language was introduced more than 20 years ago and has evolved to still be at the forefront now? Answer: BASIC. Just as the Spitfire of World War II saw many changes and variations throughout its life, the basic design could not be mistaken as it flew through the skies of Europe. In the same way, BASIC has seen many variations, additions and improvements over the years to the point where it is now seen as the easiest, most economical and one of the most powerful ways to program for Windows. While there are two versions of Visual BASIC currently available – one for DOS and one for Windows, it’s the one for Windows which really deserves the most attention. To run Visual BASIC for Windows version 3.0 requires at least Windows 3.0 but it runs optimally runs under Windows 3.1. Memory requirements are said to be at least 2Mb but it will run faster with 4Mb. You’ll also need a hard disc with about 12Mb of space, an EGA or better monitor, and a mouse. When you get hold of the package, the first thing you notice is its weight! This is not from piles of 3.5-inch floppies but mostly due to the two large manuals that come with it. These have just on 700 pages each, so you can expect to have done quite a lot of reading by the time you’re up and running the system properly. The programmer’s guide takes care of language concepts and using the development system while the language reference details each instruction and how it is used. The overwhelming thing you’ll find when flicking through the manuals for June 1994  69 the first time is the myriad of commands that look nothing like those of the old QuickBASIC. In fact, the big disap­pointment about Visual BASIC is that many of the old QuickBASIC instructions are not supported. The impression is that because you now have access to the Windows programming environment, you no longer need these “antiquated” instructions. Programming environment As with many programs these days, installation is basically a non-event. You load the Windows Program Manager, run the SETUP program on the first disc and it literally does the rest. All you need to do is fill out your registration card while you watch the graphics appear on the screen. The programming environment will probably throw most people at first glance because it looks nothing like what most program­mers would be used to. It’s fair to say that, by moving from DOS to Windows, the whole approach to programming has been changed. Back in the days of GWBASIC, just about every program was designed as a top-down program; ie, the program decided where the user would go and that usually meant starting at the top and working your way through to the bottom of the program where the END statement was found. Nowadays, programs are written using a method known as object-oriented programming where instead of the program deciding the user’s course, the user decides where the program goes next. Windows is the perfect example of this and when programming for Windows, you are really forced to follow the same format if you wish to take advantage of its graphical user interface (GUI). So instead of just writing code that goes from start to finish, you have to write code in sections or subroutines that take into account whatever the user may wish to do with your particular application. And because Windows is such a graphical interface, you have to program the windows or “forms” the user sees. However, this is actually quite easy thanks to the development environment. In fact, it’s very much like setting out a page in just about any desktop publishing system. To program in the forms, you simply click on icons in the tool box to 70  Silicon Chip This is an example layout of a form. It was created using the directory & disc tools available from Visual BASIC’s toolbox. These two tools allow you to display the directories of a given disc drive without the need to generate code. The program is activated by the two command buttons (Quit & OK). The Properties box (left) contains all the parameters of a given form, including size, colour, font & font size. The main Toolbox (above) contains all the common Windows functions; eg, dialog boxes, command buttons & scroll bars. This is the first screen of the SetupWizard installation utility. This utility generates the setup program for easy installation of your program into the Windows environment. drag down labels and command buttons, as well as pictures and icons. You have access to around 200 icons plus there are many hundreds more available on shareware which leads me to another point. Inside the package is a little catalog from BASICPro magazine which details many third-party add-on packages to add to your Visual BASIC, many of which are supported by software compa­nies here in Australia. This is a great idea because as good as Visual BASIC is, there is a definite lack in access support for the hardware ports; ie, no IN or OUT statements. However, there are a few third party companies that have packages to support these commands. Setup Wizard One of the features in version 3 which will attract a lot of interest is the new Setup Wizard utility. This program allows you to create the professional-looking setup programs for your finished product just like the one Windows uses. It automatically takes care of all the files you need and generates the master distribution discs. These can then be copied onto discs for users and they can then install the program using this setup utility. You have to provide the directory name that the program should be stored in but the user can change this when installation is taking place. There is no need for the end user to have to figure out how to install the program or where to put it. Language development If you can remember back to the days of the Commodore 64, many of which are still being used today, the BASIC language it used was quite primitive, providing only a few high-level func­ t ions. Quick BASIC improved things greatly by being able to in­clude subroutines, as well as having easy access to the BIOS and DOS routines. Now that Visual BASIC has arrived, it would seem that the complexity of the language has increased markedly and this can be either a bad or a good thing. Although there are an incredible number of instructions which allow you to do just about every­thing except brush your teeth, you have to have a memory capable of storing half a telephone book to get really on top of it. It’s not until you look at the manuals that you realise just how much is involved in writing programs for Windows and I think that was the main influence on making the development environment as functional and as powerful as possible. Flexibili­ty with this language is the key to it being able to produce just about any application you can think of. OLE capability One of the other new features which will make Visual BASIC 3 a success is its object-linking and embedding (OLE) control. This allows Visual BASIC to display and manipulate data from other Windows-based programs such as Microsoft Excel. This makes it easy to incorporate professional graphics into your programs without having to sit down and draw them line by line. The overwhelming impression is that this has been de­signed for business applications however it should be possible to incorporate circuit diagrams from say AutoCAD for Windows which will make it useful in the electronics field. All in all, Visual BASIC is a winner if you need to produce professional programs for Windows and take advantage of its position in the market place. Essentially, it bring Windows programming to a language that has long been considered as a hacker’s code. Obviously, Microsoft doesn’t agree. However, with Windows 4 due for release later this year, the word is out that the old DOS has only a few more years left in it. So in order to remain at the top of the programming heap, Visual BASIC and products like it will have to take over from the industry standard QuickBASIC 4.5 and the like. If this is the case, later versions of Visual BASIC must include easier access to hardware ports and provide more information on programming them. It still has a way to go to match QuickBASIC on that score! Visual BASIC 3.0 is available in two versions. The standard version costs $249 and contains everything you need to write the average program plus the SetupWizard utility. The Profes­ sional version retails for about $650 and contains some extra utilities, as well as information on all the routines available in the Window’s application programming interface (API). You can contact your nearest Microsoft dealer SC for more details. June 1994  71 REMOTE CONTROL BY BOB YOUNG Servicing batteries & chargers This month is the last of the series on servicing R/C equipment & we will finish off with nicad battery packs & chargers. Nicads can cause all sorts of problems, far beyond what most people expect from such a widely used component. As noted in previous columns, nicads are statistically the number one cause of trouble (after finger trouble, that is) in the modern R/C system. The key to successful modelling is preventa­tive maintenance and I cannot stress this strongly enough. The foregoing is no reflection on modern nicads for they are a vast improvement on the old button cells that I cut my teeth on. It merely indicates that the improvement in quality of modern elec­tronic equipment has completely outstripped that of the nicad. The problem with any battery, nicads included, is they contain corrosive substances which will eventually eat their way through the battery casing given enough time. Thus, if your R/C set has batteries in it, then you will eventually have battery trouble. It is as simple as that. To compound the problem, rechargeable batteries must have venting as a safety measure. Thus, at some point, corrosive gases will be vented into the transmitter (or model). This venting is usually caused by overcharging or overheating the battery. Fast charging is hard on batteries and cell life is reduced accord­ingly. However, cells designed for fast charging will not be as badly effected here as, say, cells designed for low discharge This photo shows a standard plugpack charger (left), of the type sold with all modern R/C systems. Also featured is a cycling charger made by Silvertone. This unit features 240VAC and 12VDC charging. The 12VDC feature is very useful for field charging. In operation, the start button initiates discharge & when the voltage endpoint is reached (1V per cell), the unit automatically commences the charge cycle. 72  Silicon Chip currents and trickle charging. Calculator batteries fall into this category. Fast overcharging is deadly, as is drawing too much current from cells designed for low current operation. One very common mistake made by modellers is to buy cheap nicads which are usual­ly designed for calculator use and then use them in the receiver battery pack. The instantaneous start-up current on a servo motor can run as high as 1A. Thus, a model with six servos could easily require up to 6A at some point in its operation. Calculator batteries will turn up their toes very quickly indeed under these conditions. However, calculator batteries are usually OK in the transmitter battery pack, as the current drain is in the order of a steady 100-150mA. Receiver packs Receiver packs should be made up from good quality cells designed for high current operation. The other problem introduced by low rate cells in receiver operation is the internal resist­ance of the cell. Low rate cells have a higher internal impedance and this will cause spikes on the receiver’s supply rails. These spikes can cause serious problems, particularly at extremes of range when all the servos start to jitter. This raises the aver­age servo current and causes a voltage drop from the battery pack, thereby reducing the range. This reduced range further increases the servo jitter and suddenly the receiver/servo/batteries are locked into a death spiral. The result is one broken model, one modeller scratching his head over why his receiver ran out of range, and a receiver and battery that works perfectly once the abnormal load is taken off the system. If you suspect this sort of problem, do a range or sensitiv­ity check with only one servo in the system. Repeat this test with all servos included and note the difference in range. If there is a significant difference in range, suspect the batteries or noisy servos. Remove one servo at a time, replacing the previous­ly removed servo and again note the range. If one servo shows up as a problem, then check the noise suppression filters in the servo. If the servos all check out OK, suspect the battery. Replace the battery with one made up from high rate cells. This should cure the problem. Fast charging raises the temperature of the cell, as does excessive current. Accidental short circuits are quite damaging to nicads, not necessarily immediately but later on in their life. Worse still, the vented gases given off during the trauma will start to corrode any surrounding metal and this includes electronic components anywhere near the batteries. With this in mind, start your battery servicing with a good look around the area in which the battery is housed. Check to ensure that PC boards are clean and not showing signs of corro­ sion. Corrosion on PC boards with solder resist masks often shows up as a dark green stain. Hot, vented battery gases will rise and lay a corrosive and conductive coating on any surface directly above the battery. More often than not, this happens to be the encoder PC board in the transmitter. The conductive coating can have a devastating effect on timing circuits and in time eat its way right through copper tracks. Black wire syndrome I have spoken often about the “black wire syndrome” in the past and I will mention it again here. Black wire is a corrosive process in which all of the copper in the negative lead (usually) is gradually replaced by some sort of black garbage. This wire has increased resistance and becomes very black and brittle. It will eventually fall off the terminal it is soldered to but not before it transfers the corrosion to anything to which it is connected. Thus, the battery connectors, switch harness, and the switch contacts themselves must be subjected to close scruti­ny. Nor is this effect confined to the negative lead. I have seen all types and colours of wire effected. To check for black wire, simply pull back the insulation as near to the solder joint as possible. If the copper or nickel plating is bright and shiny, just put the insulation back where you found it. If the conductor is showing signs of staining or corrosion, then replace the entire length with nickel plated multi-strand wire. Do not use untinned copper conductors on battery leads. If the battery lead in the transmitter has a connector in it, then pull the connector apart and check for corrosion on the pins. Once black wire has set in, this connector will not pull apart as the two halves become welded into a corrosion riddled whole. Do not bother to try to clean this connector if it has mild staining, for it will just keep staining. Just replace it or bypass it directly with a hard wired installation. I might add here that CRC-226 helps to minimise the forma­tion of this type of corrosion, particularly on connectors and switches, so keep the ends of the batteries, connectors and switches moist with a coating of CRC-226. Do not forget to in­spect the charging leads and socket as these are all in the battery path and often corrode badly. The charging socket is also open to dust, moisture, overspray from painting models and worst of all, burnt castor oil fumes. Check these items carefully and keep up the CRC. This business of overspray is a point I have never raised before but I have lost count of the number of servo leads I have had to replace because someone has forgot to mask their servo connectors before spraying the model. Painted servos and connec­tors may make a great fashion statement but they do not enhance the electrical performance of the system. If you must spray the model with the servos, VCR ALIGNMENT TOOL KIT • 7 Assorted head & guide aligners • Hex key set • Retaining ring remover • 3 Reversible screwdrivers – SML – Flat – Philips • Spring hook • Fitted vinyl • Micro screwdriver • Zippered • VCR head puller Our Low Price $99.95 WOMBAT COMPONENTS WOMBAT COMMUNICATIONS 83 - 85 Railway Ave Werribee, Vic 3030 Phone: (03) 742 7330 Fax: (03) 741 6834 battery packs and charge receptacles in it, then please make sure they are well sealed against paint. Once you are satisfied that all of the external areas are free of corrosion, then it is time to go into the battery pack itself. Take off the heatshrink enclosing the bundle of cells and examine the ends of the cells. If they are badly salted, the pack should be dumped. Mild salting can be cleaned off with a toothbrush and CRC-226. Mild salting does not mean the pack CALLING ALL HOBBYISTS We provide the challenge and money for you to design and build as many simple, useful, economical and original kit sets as possible. We will only consider kits using lots of ICs and transistors. If you need assistance in getting samples and technical specifications while building your kits, let us know. YUGA ENTERPRISE 705 SIMS DRIVE #03-09 SHUN LI INDUSTRIAL COMPLEX SINGAPORE 1438 TEL: 65 741 0300    Fax: 65 749 1048 June 1994  73 REMOTE CONTROL – Servicing Batteries is at its end of life but does indicate that the periodic inspections must be increased in frequency. Once this salting starts, black wire is not far behind. Sadly, having made a statement like that I must now qualify it. First, black wire is not confined to the negative lead so check all leads. It can occur with no evi­ dence of salting on the batteries so stay alert. Black wire is an elusive foe so always exercise extreme caution when inspecting the batteries and associated components. One other point – do not use your best soldering iron tip when soldering badly corroded battery terminals. This corrosion will contaminate the tip and make soldering very difficult for some time. Finally, be sure to wash your hands after handling old batteries. They are often coated with chemicals which have spilled over the entire surface of the battery. These chemicals are very corrosive. If the cells are moist from internal chemi­cals, dump the pack. Castor oil often migrates down the battery lead in the model and coats the cells under the heatshrink and it is sometimes difficult to tell the source of the moisture. deliv­er a trace that is quite distinct with a high start point, gently sloping centre portion and the sharp drop at the end. The big difference between the two, however, is that the Yuasa trace is on average 0.1V higher over the flat portion, whilst the Saft curve is at least 10-20% longer. All nicads will exhibit these distinct differences as they reflect the internal construc­tion, chemical composition and condition of the cell. As batteries age, they change the shape of the graph and again it is possible to tell an ageing battery from its graph. And yes, you can see evidence of memory, even in modern cells. Some traces exhibit a very distinct kink in the voltage curve which in some cases goes completely with cycling. I have always recommended cycling before every charge for two very good rea­ sons: (1) it gives you a known starting point for your charge time, thus helping to prevent overcharging; and (2) it moves the chemicals around inside the cell and helps to minimise the formation of crusty deposits on the plates. The modern battery is supposedly “Be sure to wash your hands after handling old batteries. They are often coated with chemicals which have spilled over the entire surface of the battery”. It is now time to check the cells electrically. First, charge them fully and if you have the facilities, then cycle the batteries once or twice and note the capacity. At Silvertone, we do a routine cycle and battery graph on all sets we service. This tells us the full story: cell voltage, state of the cells and capac­ity. In time, I have learned to interpret these graphs and can almost tell the brand of cell from the shape of the trace. For example, Yuasa 500mAh cells deliver the almost classi­ cal nicad graph – ­ high start point, flat middle section and sharp drop off at the end. Saft 500mAh cells, on the other hand, 74  Silicon Chip immune from overcharging and Saft state that at the C/10 rate, their cells will stand 20,000 cycles. In practice, I have found that Saft cells give excellent service over very extended periods of time. I still get sets in that I built in 1974 with original battery packs in good condition. Thus, I am very reluctant to change brands for this reason. The problem with some batteries, particularly those offering high capacity in the AA size, is that this extra capaci­ty is obtained by leaving out some the safety chemicals. Thus, cell life is often reduced as a result. Finally, inspect the external casing of the cells for crash damage or other physical distortions. Cells often get pushed in during a crash and in time will rupture in use. Check the termi­nal voltage on each individual cell after a full charge and a partial discharge. All cells should be within 0.1V of each other. If one cell is outside this limit, be careful. I do not recommend replacing one cell in an old pack but sometimes it is a matter of convenience and cost. Once you are satisfied that the cells are OK, replace the heatshrink sleeving and remount the battery. A good source of small quantities of the larger diameter heat shrinks suitable for battery packs is your local model shop. They use these sizes for covering helicopter rotor blades. Chargers With regard to the charger, there is not much to go wrong with these units. Check for paint overspray on the connectors as these things kick around the workshop and are rarely if ever looked after. A good scrub with the toothbrush and CRC-226 is all that is usually needed. Most chargers supplied with modern R/C systems are simply a plugpack with two diodes, two LEDs and a dropping resistor for each battery. The occasional LED goes out and sometimes the transformer goes open circuit but these are rare failures. A quick check of the voltage on the output pins is in order, making sure that the polarity is correct. Often, modellers replace these connectors to suit the set they are using. Likewise check the soldering on these joins if they pres­ent. Some modellers have never learned how to solder and twisted leads are the order of the day. Finish off with a quick check of the current from each charge lead. This will normally be the C/10 rate or 50mA for a 500mAh cell. To my mind, a better way to handle nicads is to discharge them immediately after use so that they are stored in the dis­charged state and the internal chemicals are in their least active mode. Thus, they are least likely to get up to mischief between sessions. The cycling charger is ideal for this approach. When the discharge is complete, the discharge relay drops out and the unit does not even need to be unplugged. you then simply switch on the charge power the night before your next modelling session and 14 hours SC later you are ready to howl. 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. 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. 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 VINTAGE RADIO By JOHN HILL Timber cabinets, antique dealers & vintage radio prices How much should you pay for an old radio, particularly one that no longer works? We take a look at this question this month & offer some advice on restoring old timber cabinets. “Purists” (those collectors who insist that their collec­ tions remain original at all costs) would shudder at the thought of scraping down a timber radio cabinet and “doing it up” – particularly if modern materials such as “Estopol” and “Aqua­dhere” are used in the process. While keeping things completely original sounds OK in theo­ ry, very few timber cabinets are good enough to leave as they are. In 10 years of radio collecting, I have found only three timber cabinets that were good enough to leave in their original state. Even then, they all required quite a bit of work before they looked reasonably presentable. In most cases, timber cabinets deteriorate to such a dread­ful state of disrepair that no-one would want them as they are and they would be Above: this magnificent looking “wood grain” finish is only a painted on veneer which produces a remarkably good effect. This technique produced “wood grains” that no real tree could possibly match. Right: this Philco receiver is another with a false veneer front. In this example, the effect is produced with a brush and stencil. The fine white vertical lines in the speaker fretwork are not inlaid timber as they appear to be but the plywood of the cabi­net. 80  Silicon Chip most unwelcome in any lounge room. Any 50-60 year old console or other timber cabinet radio that has spent a few years in an outside shed is usually a fairly uninteresting piece of equipment, or furniture, depending on your point of view. Some become quite loose in the joints and will have lost more of their original lacquer than they retain. When this is the case, who wants them in original condition? I certainly don’t! Invariably, it is standard procedure, at least as far as I’m concerned, to refurbish timber cabinets. The process is long and time-consuming and involves completely stripping the old finish, sanding the cabinet smooth and re-gluing rickety joints and loose veneer. And that’s only the preparatory work! At this stage one has the choice of using wood stains but in most instances I refrain from this treatment and allow the natural colour of the timber to show through. Wiping down with a damp cloth will show up the true tonings of the wood veneer. Staining will often dull it and smother the timber’s warm appeal. Plywood cabinets Now a word of warning. Not all timber cabinets can be suc­cessfully refurbished! Stripping some cabinets will result in nothing to work with other than plain, unfigured plywood. Back in the early 1930s (the great depression years), radio manufacture was very competitive and many manufacturers went out of business during that period. Any process that could trim costs would give an advantage over a competitor and so cabinet costs were trimmed considerably. They were made of much lighter materi­als and, in some cases, the expensive walnut veneers that were in common use at that time to enhance the cabinet’s appearance were not used. Instead, the “veneer” was painted onto plain plywood and often gave a surprisingly good effect. All sorts of knotty timber patterns were developed – the sort of patterns that no real tree could possibly produce naturally. The Univox cabinet shown in some of the accompanying photo­graphs is one of these paint-on jobs and, after about 60 years, it has reached a stage where the painted-on wood grain has start­ed to shrink, with splits appearing in the paint work. Each split reveals the whitish coloured plywood underneath and to strip such a cabinet would result in a bland pine coloured surface with no wood grain finish whatsoever. Making repairs If a cabinet of this type is to be refurbished, the origi­nal “wood grain” must be left intact. That means that splits in the shrunken finish have to be filled in with a matching stain or colour and the whole lot covered with a clear, satin finish lacquer – not an easy task by any means! Just how permanent a restoration of this nature would be is another matter. The old paint work may continue to crack and deteriorate and the lacquer After 60 years, the painted “veneer” starts to shrink and crack, thus making restoration a difficult task. The panel to the right of the cracked section shows how featureless the plywood under­neath really is. That is what the cabinet would look like if the original finish is removed. This old Radiola was bought for $40 from a secondhand dealer. Although this receiver “worked”, it was later discovered that mice had chewed away three quarters of the loudspeaker cone. No wonder the sound was soft & distorted! would be the only thing holding it in place. Such a repair would probably be, at best, a temporary measure. The Philco receiver (see photograph) also has a similar “el cheapo” front panel. In this instance, a stencil has been used to produce thin vertical lines to create an impression of inlaid timber. It is all a fake! The “inlaid” strips are the original plywood and the darker “wood grain” has been applied with a brush. Once again, any attempt to strip the front panel would result in nothing other than a plain piece of uninspiring ply­wood. However, while some collectors may be critical of such cheap and nasty production methods, who would have thought way back in the 1930s that someone would want to restore the cabinet (and the radio) some 50 or 60 years later? Anyway, you have been warned! Always inspect a radio cabi­net very closely before deciding to strip it down to bare wood. In some instances, the June 1994  81 The price of this little Peter Pan radio came tumbling down when the on/off switch decided not to work. If a dealer has trouble demonstrating a radio, it is in the best interests of the buyer not to interfere. No matter what, the dealer will still make a reasonable profit. due to myself and fellow vintage radio writer, Peter Lankshear. Collectively, we have encouraged many people to collect and restore old radios, thus creating a demand and a corresponding increase in prices. However, while I know that I have been instrumental in getting some collectors started in this interesting hobby, it was bound to happen anyway. As soon as something becomes rare or is no longer made, that’s when people start collecting it. Valve radios had already reached that stage when I first became inter­ested in them about 10 years ago and the movement has gathered considerable momentum since then. Secondhand and antique dealers are more likely to be the ones who initiated the price increases in old radios. Their prices are always based on what the market will pay, not the price they pay for their merchandise. While they do spend a lot of time chasing auctions and the like, they seem to operate on much higher margins than most retailers. Recent acquisitions The octal valves in this Scharnberg Strauss 4-valve receiver date it at around the late 1940s. It’s a fairly uncommon receiver & was obtained for $70 but that included a set of headphones. bare wood may be a good deal barer than you think! So much for timber radio cabinets. Let’s now move onto something else. Vintage radio prices Have you noticed lately that, despite the recent economic down turn, vintage radio prices did not come down very much. My observation is that 82  Silicon Chip prices are still fairly inflated and, as a result, collectors are not buying. I have also heard of cases where collectors have sold their radios without getting their money back. Surely that is an indication that they may have paid more for their radios than they were really worth. The inflated prices of valve radios (so I have been told) have been largely Although secondhand dealers have to eat just as you and I, some of their prices are unrealistic to say the least. But these high prices appear to be coming down. While on a recent holiday, I managed to pick up a few receivers at fairly reasonable prices considering they were bought from dealers. I just happened to be in the right shops at the right times. The first one was a mid 1950s 5-valve AWA Radiola, a fairly large mantel model which I was able to purchase for $40. It was in going order but only just. The cabinet was maroon and cream and although these colours are difficult to identify through the coating of grime, I am sure that it will clean up OK. As there were no cracks in the cabinet or dial and it still had its origi­nal knobs (very important for that particular model), it was a good buy for the price. Next was a cream Peter Pan, an identical model to the one pictured on the front of the 1993 Vintage Radio Calendar. The price on the Peter Pan was $95. Obviously the dealer didn’t know about the Vintage Radio calendar, otherwise it would have been $195. It looked clean and tidy and was supposed to be in good working order. Once again, the set still had its original knobs which is important because, like the previously mentioned Radi­ ola, they are special knobs. In the same shop was an empty cutlery box that my wife wanted, so I bartered for a better price on the radio if we bought both. The radio came down to $75. I then asked for a demonstration on the radio and it would appear as though the on/off switch decided at that very moment to play up a bit. The little Peter Pan would not switch on –it was completely dead! Another power point was tried with the same result. After a short discussion about burntout power transformers and other equally frightening topics, I offered $40 and the Peter Pan was mine. Later, when I plugged it in and switched on, it lit up first go. However, as the dealer was about 130km away at that stage, it was just too far to go back and offer him the extra money. He most likely made a reasonable profit anyway! Many years ago, I learned never to interfere with dealers when they are demonstrating a radio. If they turn it off instead of on, or if the selector These Browns Type “X” high impedance headphones came with the Scharnberg Strauss radio. They are in near-new condition but definitely need a new plug. The attached 240V electric light fitting is an indication of the strange (& often dangerous) things one encount­ers when collecting old radios & associated equipment. switch is on a shortwave band or the gramophone setting, then that’s their problem! They should be more familiar with the articles they are selling. It pays to act dumb (and can I act dumb) and let them twiddle with the knobs. If the set comes to life and starts working, then it’s going to cost heaps more than if it remains mute. I have a pet phrase that I use when a radio fails to work and that is, “you can’t ask much for it when it doesn’t go!” Scharnberg Strauss The “Musician” is a dual-wave 5-valve superhet built by Eclipse Radio & is typical of budget-priced console re­ceivers from the mid-1930s. It uses a 12-inch Saxon loudspeaker & should perform quite well when restored, although the cabinet certainly lacks style. The third receiver was of a brand name that one doesn’t see very often and that is “Scharnberg Strauss”. Apart from the name, there was nothing really exciting about it as it was just a straightforward 4-valve mantel in a rather plain looking green plastic cabinet. It was in fair working order and I bought it for $70. The asking price was $95. Normally, $70 would be more than I believe such a set is worth. However, in this case, a pair of headphones went with the deal – not just any old set of headphones but a high-impedance set of Browns Type X in almost new condition. In the same shop, there was a 1936 5-valve, dual-wave con­sole bearing the name “Musician” on the dial. It was, in fact, one of those numerous Eclipse Radio products that were so common during the 1930s. Any dual-wave 1930s console that is complete with its original knobs and 12-inch (30cm) electrodynamic speaker, and has a cabinet in reasonable condition, has to be good buying from a dealer at $120. I didn’t haggle over the price with this one as it seemed fairly reasonable to me. Readers in capital cities such as Melbourne and Sydney may be amazed that valve radios can be bought from dealers for these prices. My advice is to get out into the countryside where such items are more reasonably priced. However, buying privately is always a better proposition than buying from dealers, although it can involve a lot of chasing around. That’s one thing you pay for SC when buying from a dealer. RESURRECTION RADIO Valve Equipment Specialists Repairs – Restoration – Sales VALVES – 1200 types in stock    EL34/BCA7 matched $30 ea.    6L6GC matched $28 ea. Parts are available for the enthusiast, including over 900 valve types, high voltage cap­a citors, transformers, dial glasses, knobs, grille cloth etc. Circuit diagrams for most Australian makes and models. Send SAE for our catalog. WANTED: Valves, Radios, etc. Purchased for CASH Call in to our NEW showroom at: 242 Chapel Street (PO Box 2029), Prahran, Vic 3181. Phone: (03) 510 4486; Fax (03) 529 5639 June 1994  83 AMATEUR RADIO BY GARRY CRATT, VK2YBX Review: Kenwood’s TS50S HF amateur band transceiver Claimed to be the world’s smallest HF amateur band tran­sceiver, the Kenwood TS-50S was released early in 1993 & has enjoyed a good reputation in amateur circles ever since. Despite its small size (179 x 60 x 233mm), the unit offers a full 100 watts of RF output power in the FM, SSB and CW modes, and a respectable 25 watts in the AM mode. The transmitter covers 160 metres through to 10 metres and the receiver offers general coverage from 500kHz to 30MHz. Like other VHF Kenwood transceivers, the TS-50S uses a microphone equipped with four user programmable function keys, allowing control of up to 26 transceiver functions. The The Kenwood TS-50S has many functions which are control­lable by the four programmable buttons on the microphone. Note the large liquid crystal display & the highlighted scanning mode. 84  Silicon Chip status of these functions is shown on the large liquid crystal display on the front panel of the transceiver. First used in the TS-950SDX HF transceiver, Kenwood has also incorporated their computer menu system into the TS-50S, to allow the user to configure 39 operating parameters, including operating frequency, RF output power, AGC mode, IF filter select, CW offset, RF meter sensitivity, sub-audible tones, five separate scan parameters, receiver incremental tuning, microphone gain, repeater tone frequency select, and many others. The receiver is also equipped with Kenwood’s exclusive “AIP” system (Advanced Intercept Point) which improves the re­ceiver’s dynamic range to a maximum of 105dB. When used in conjunc­tion with the inbuilt 20dB attenuator, this allows the user to overcome levels of high interference and strong adjacent signals. There is also a very effective IF SHIFT control, which allows the user to shift the IF passband by 1.5kHz or so, without changing the receiver frequency. Using this control, it is possible to completely eliminate adjacent frequency interference, in the majority of situations. Programmable memories The transceiver has 100 user pro- This is what the TS-50S transceiver looks like with the lid removed. There are no user serviceable parts inside! grammable memories, for independent storage of transmit and receive parameters, such as frequency, mode, and IF filter settings. The “Memory Shift” function facilitates the transfer of data to either of the two inbuilt VFOs. For CW enthusiasts, the transceiver has a “CW Reverse” function, which effectively switches from the upper sideband default position to the lower sideband position, thereby removing any adjacent channel interference heard with the transceiver in the default setting. The CW receive pitch can also be selected from 400 to 1000Hz in 50 Hz steps, without affecting the transmit sidetone. There is also an option­ al 500Hz IF filter – the YK-107C available for narrow-band CW operation. The rear panel of the transceiver supports a 3.5mm mono phono socket to allow connection of a CW key or electronic keyer. The more exotic data modes of HF operation are also sup­ported and virtually any TNC can be connected via the microphone socket. As the transceiver displays only the carrier frequency if either sideband operation is selected, it is necessary for the operator to add the modulating frequency to the displayed frequency in order to accurately calculate the actual operating frequency. Thus, to select an RTTY “mark” frequency of 14.080, the operator must tune to 14,082.125kHz on the transceiver in the LSB mode; ie, 14,082.125kHz - 2.125kHz = 14.080 MHz. The transceiver tuning can be incremented in 5Hz steps, so quite accurate results can be achieved. As there are two inbuilt VFOs, split frequency and cross band operation is also possible with the TS-50S. In fact, split frequency “channels” can also be memorised in any of the 100 memory channels. The transceiver is supplied with quite heavy-duty DC power leads, capable of carrying the 20.5 amps of current required at full RF output power. In the receive mode, the maximum current required is 1.45 amps. As this is not an insignificant figure, there is a power feature called “APO” (automatic power off), which switches the transceiver off, if none of 20 odd major controls are operated for a 180-minute period. Although this function can be de-programmed by the user, it should go a long way towards eliminating the possibility of a flat battery. Optional accessories The TS-50S has a large range of optional accessories, in­ cluding two automatic antenna tuners, (AT-300 for fixed opera­tions, AT-50 for mobile use), a 5-band helical antenna (MA-5), the SO-2 temperature compensated crystal oscillator, a range of desk and mobile microphones, various extended DC and antenna tuner cables, mobile speakers, a bumper mount for the MA-5 anten­na, and the YK-107C CW filter. Priced at $1884 RRP, the TS-50S may not suit every budget but the small size, features and ease of operation make it the ultimate choice for many mobile operators, as proven by the many units already in operation in SC Australia. June 1994  85 Silicon Chip Batteries; Delay Unit For Automatic Antennas; Workout Timer For Aerobics Classes; 16-Channel Mixing Desk, Pt.2; Using The UC3906 SLA Battery Charger IC. BACK ISSUES April 1990: Dual Tracking ±50V Power Supply; VOX With Delayed Audio; Relative Field Strength Meter; 16-Channel Mixing Desk, Pt.3; Active CW Filter For Weak Signal Reception; How To Find Vintage Radio Receivers From The 1920s. September 1988: Hands-Free Speakerphone; Electronic Fish Bite Detector; High Performance AC Millivoltmeter, Pt.2; Build The Vader Voice; Motorola MC34018 Speakerphone IC Data; What Is Negative Feedback, Pt.4. Alarm-Triggered Telephone Dialler; High Or Low Fluid Level Detector; Simple DTMF Encoder; Studio Series 20-Band Stereo Equaliser, Pt.2; Auto-Zero Module for Audio Amplifiers (Uses LMC669). November 1988: 120W PA Amplifier Module (Uses Mosfets); Poor Man’s Plasma Display; Automotive Night Safety Light; Adding A Headset To The Speakerphone; How To Quieten The Fan In Your Computer. October 1989: Introducing Remote Control; 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. April 1989: Auxiliary Brake Light Flasher; What You Need to Know About Capacitors; Telephone Bell Monitor/ Transmitter; 32-Band Graphic Equaliser, Pt.2; LED Message Board, Pt.2. 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. May 1989: Electronic Pools/Lotto Selector; 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. June 1989: Touch-Lamp Dimmer (uses Siemens SLB0586); Passive Loop Antenna For AM Rad­ios; Universal Temperature Controller; Understanding CRO Probes; LED Message Board, Pt.4. July 1989: Exhaust Gas Monitor (Uses TGS812 Gas Sensor); Extension For The Touch-Lamp Dimmer; Experimental Mains Hum Sniffers; Compact Ultrasonic Car Alarm; NSW 86 Class Electric Locomotives. September 1989: 2-Chip Portable AM Stereo Radio (Uses MC13024 and TX7376P) Pt.1; 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; Installing A Clock Card In Your Computer; Index to Volume 2. 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. 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. March 1990: 6/12V Charger For Sealed Lead-Acid June 1990: Multi-Sector Home Burglar Alarm; Low-Noise Universal Stereo Preamplifier; Load Protection Switch For Power Supplies; A Speed Alarm For Your Car; Design Factors For Model Aircraft; Fitting A Fax Card To A Computer. 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; Weather Fax Frequencies. 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: Music On Hold For Your Tele­ phone; Remote Control Extender For VCRs; Power 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. 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. December 1990: DC-DC Converter For Car Amplifiers; The Big Escape – A Game Of Skill; Wiper Pulser For Rear Windows; Versatile 4-Digit ORDER FORM Please send me a back issue for: ❏ May 1989 ❏ June 1989 ❏ November 1989 ❏ December 1989 ❏ April 1990 ❏ June 1990 ❏ October 1990 ❏ November 1990 ❏ March 1991 ❏ April 1991 ❏ August 1991 ❏ September 1991 ❏ January 1992 ❏ February 1992 ❏ June 1992 ❏ July 1992 ❏ January 1993 ❏ February 1993 ❏ June 1993 ❏ July 1993 ❏ November 1993 ❏ December 1993 ❏ April 1994 ❏ May 1994 ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ September 1988 July 1989 January 1990 July 1990 December 1990 May 1991 October 1991 March 1992 August 1992 March 1993 August 1993 January 1994 ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ November 1988 September 1989 February 1990 August 1990 January 1991 June 1991 November 1991 April 1992 September 1992 April 1993 September 1993 February 1994 ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ April 1989 October 1989 March 1990 September 1990 February 1991 July 1991 December 1991 May 1992 October 1992 May 1993 October 1993 March 1994 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 ___________ 86  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. Combination Lock; 5W Power Amplifier For The 6-Metre Amateur Transmitter; Index To Volume 3. January 1991: Fast Charger For Nicad Batteries, Pt.1; Have Fun With The Fruit Machine; Two-Tone Alarm Module; Laser Power Supply; LCD Readout For The Capacitance Meter; How Quartz Crystals Work; The Dangers When Servicing Microwave Ovens. February 1991: Synthesised Stereo AM Tuner, Pt.1; Three Inverters For Fluorescent Lights; LowCost Sinewave Oscillator; Fast Charger For Nicad Batteries, Pt.2; How To Design Amplifier Output Stages; Tasmania's Hydroelectric Power System. March 1991: Remote Controller For Garage Doors, Pt.1; Transistor Beta Tester Mk.2; Synthesised AM Stereo Tuner, Pt.2; Multi-Purpose I/O Board For PC-Compatibles; Universal Wideband RF Preamplifier For Amateurs & TV. 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. 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; Setting Screen Colours On Your PC. 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; Electric Vehicle Transmission Options; Tuning In To Satellite TV, Pt.1. July 1991: Battery Discharge Pacer For Electric Vehicles; Loudspeaker Protector For Stereo Amplifiers; 4-Channel Lighting Desk, Pt.2; How To Install Multiple TV Outlets, Pt.2; Tuning In To Satellite TV, Pt.2; PEP Monitor For Amateur Transceivers. 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; Build A Fax/Modem For Your Computer; 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 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; Modifying The Windows INI Files. December 1991: TV Transmitter For VCRs With UHF Modulators; Infrared Light Beam Relay; Solid-State Laser Pointer; Colour TV Pattern Generator, Pt.2; Windows 3 & The Dreaded Un­ recov­erable Application Error; 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 Receiver. 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 Direct­ ories; Valve Substitution In Vintage Radios. April 1992: Infrared 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; LowCost 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; What’s New In Oscilloscopes?; A Look At Hard Disc Drives. July 1992: Build A Nicad Battery Discharger; 8-Station Automatic Sprinkler Timer; Portable 12V SLA Battery Charger; Off-Hook Timer For Tele­phones; Multi-Station Headset Intercom, Pt.2. 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 Sine­wave Inverter, Pt.5; Making File Backups With LHA & PKZIP. March 1993: Build A Solar Charger For 12V Batteries; An Alarm-Triggered Security Camera; Low-Cost Audio Mixer for Camcorders; Test Yourself On The Reaction Trainer; 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; A Look At The Digital Compact Cassette. May 1993: Nicad Cell Discharger; Build The Woofer Stopper; Remote Volume Control For Hifi Systems, Pt.1; Alphanumeric LCD Demonstration Board; Low-Cost Mini Gas Laser; 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; A Digital Voltmeter For Your Car; Remote Volume Control For Hifi Systems, Pt.2; Double Your Disc Space With DOS 6. 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. August 1993: Low-Cost Colour Video Fader; 60LED Brake Light Array; A Microprocessor-Based Sidereal Clock; The Southern Cross Z80-based Computer; A Look At Satellites & Their Orbits; Unmanned Aircraft – Israel Leads The Way; Ghost Busting For TV Sets. 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 Electronic Cockroach; Restoring An Old Valve Tester; Servicing An R/C Transmitter, Pt.1. October 1993: Courtesy Light Switch-Off Timer For Cars; FM Wireless Microphone For Musicians; Stereo Preamplifier With IR Remote Control, Pt.2; Electronic Engine Management, Pt.1; Mini Disc Is Here; Programming The Motorola 68HC705C8 Micro­ controller – Lesson 2; Servicing An R/C Transmitter, Pt.2. November 1993: Jumbo Digital Clock; High Efficiency Inverter For Fluorescent Tubes; Stereo Preamplifier, Pt.3; Build A Siren Sound Generator; Electronic Engine Management, Pt.2; More Experiments For Your Games Card; Preventing Damage To R/C Transmitters & Receivers. December 1993: Remote Controller For Garage Doors; Low-Voltage LED Stroboscope; Low-Cost 25W Amplifier Module; Peripherals For The Southern Cross Computer; 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; Even More Experiments For Your Games Card. 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: More Than Just Bags Of Wind; Building A Simple 1-Valve Radio Receiver. 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; Switching Regulators Made Simple (Software Offer). 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; Spectrum Analysis Using An Icom R7000 Communications Receiver. May 1994: Fast Charger For Nicad Batteries; Induction Balance Metal Locator; Muilti-Channel Infrared Remote Control; Dual Electronic Dice; Two simple servo Driver Circuits; Electrronic Engine Management, Pt.8; Passive Rebroadcasting For TV Signals. PLEASE NOTE: all issues from November 1987 to August 1988, plus October 1988, December 1988, January, February, March & August 1989, May 1990, and November and December 1992 are now sold out. All other issues are presently in stock. For readers wanting articles from soldout issues, we can supply photostat copies (or tear­sheets) at $7.00 per article (incl. p&p). When supplying photostat articles or back copies, we automatically supply any relevant notes & errata at no extra charge. June 1994  87 PRODUCT SHOWCASE New synthesiser from Yamaha Yamaha Music Australia has recently released the first synthesiser to employ Virtual Acoustics (VA), a sys­tem which generates waveforms by way of a computer model of the actual instruments. Virtual Acoustic Synthesis simulates in software the complex vibrations, resonances, reflections and other natural acoustic phenomena that occur with a real acoustic instrument. The VA model simulates the effect of an instrument being blown, plucked, bowed or hit, responding to subtle changes in lip shape, air pressure and playing technique. The first Virtual Acoustic Synthesiser, the Yamaha VLl (standing for Virtual Lead), features a VA subset called S/ VA (self-oscillating VA). S/VA is ideal for simulating instruments that vibrate through the continuous application of a constant pressure, namely wind and bowed string in­struments. It has no oscillators, no preset waveforms, no samples and in fact, none of the sound generation concepts employed in conventional synthesisers. New pressure sensor in a DIP package Sensym has released a new se­ ries of low cost, temperature com­pensated, solid state pressure sen­sors in a DIP package. They are intended for applications where automated board mounting, calibrated span and offset (0°C to 50°C), stability, reliability and low cost are important design requirements. The pressure ports allow easy connection via standard plastic tub­ing. The devices are available in either absolute or gauge configurations in the following pressure ranges: -1, 5, 15, 30 and 100 psi full scale. The output of the de­vices is ratiometric to the supply voltage and operation from any DC source up to +20 volts is accept­able. The SDX devices feature an integrated circuit sensor element and laser 88  Silicon Chip trimmed thick film ce­ramic housed in the solvent resist­ant DIP package. All SDX parts are calibrated for span to within 3.5% and provide a zero pressure out­ put offset of ±1mV max. For further information call NSD Australia on 008 335 623 or (03) 890 0970. The VLl is equipped with a 49-note keyboard with 2-note polyphony and an integral breath controller. It provides the performer with control over the subtle nuances which affect the instrument's timbre, such as the ef­fects of note-to-note transitions and breath or reed pressure. Since VA stores mathematical models of real instruments, this data can also be used to create virtual instruments that couldn't exist in the real world – a bowed saxophone or blown violin, for example. Creating new instruments is simply a matter of defining the appropriate characteristics, its size and shape, the type of reed or bow, the length of the sound column, and so on. Using a combination of the keyboard, breath controller, foot ped­als or other controllers, a musician can then play the instrument as expressively as if it physically existed. For further information, contact Yamaha Music Australia by phone on (03) 699 2388, or fax (03) 699 2332. Development tools for PIC16 microcontrollers Parallax makes affordable development tools for the PIC16Cxx micro­ c ontrollers from Microchip Technol­ogy. Parallax's tools include assem­blers, programmers, downloaders and simulators that work with IBM PC compatibles running DOS. The Parallax PIC assembly language offers both 8051-style mnemonics and Microchip's instruction set. Programs are written on the PC using any text editor, then assembled and programm ed into a PIC. The programmer blank checks, reads, verifies and programs PICs. The programmer's two LIF sockets accept all 18- and 28-pin DIP parts for the PIC16C5x, PIC16C71 and PIC16C84. ZIF and SOIC adaptors are also available, as well as a DIP adaptor for the new PIC16C64. The downloader speeds prototype development by plugging in place of a PIC16C5x in the target system, and runs at 8MHz. Substituting the down­loader for a real PIC allows rapid code testing without the user having to re­move, erase, program and replace ac­tual chips. The new TrueFlight programmer/ downloader supports the newer PIC16C71 and PIC16C84. Using a pro­ d uction part and an on-board flash UV eraser, TrueFlight quickly pro­grams and erases PIC16C71s. The EEPROM-based PIC16C84 is erased electrically. Using either chip and a cable connected to the target system, TrueFlight functions as a 20MHz download er. The simulator models a PIC16C5x in software on the PC, showing regis­ters, flags, the stack and pins. The simulator can be stepped, breakpoints can be set, and a watchdog timer ena­bled. Most of the-registers can be al­ tered by the user during simulation. For more information contact MicroZed Computers, PO Box 634, Armidale. Phone (067) 72 2777 High speed recorder from Yokogawa A new floppy disc based high speed transient recorder featuring 1Mb of acquisition memory has been released by Yokogawa. Designated the model ORM1200, this recorder complements Yokogawa's recently released memory card recorder, the ORP1200. The ORM1200 can be connected directly to voltages from millivolt lev­els up to ±500V and a wide range of thermocouples. 4, 8 or 16 input chan­nels may be fitted, with an optional further 16 logic channels available. Similar to the ORP1200, the ORM1200 incorporates the benefits of a pen recorder, oscilloscope, memory recorder and an XY recorder in one portable unit. A real time electroluminescent display capable of Newtrik A2 audio test instrument Amber Technology has announced the new Neutrik A2 audio test & service system, a high per­formance, comprehensive 2-chan­nel test and measurement instru­ment featuring a wide range of analysing/sweeping/graphics func­tions, a versatile signal generator, oscilloscope and graphic printer in­terface. The Newtrik A2 provides all the instrument functions re­ quired for audio testing applica­tion in recording studios, broad­ c ast stations, consumer electronics servicing and audio equipment manufacturing. The A2 has a clear "one button­ one function" keyboard with a large, easy to read LCD graphic display, enabling complex tests to be per­formed without reference to the manual. The A2 also transfers graphic and text hard copy of all measurements to any Epson, IBM or HP compatible standard printer. Featuring two balanced, fully dif­ferential inputs, the A2's analyer section can simultaneously meas­ ure level, crosstalk, level-ratio and phase in fully automatic THD, IMD, noise, wow and flutter, scope, drift and spectral analysis modes. The integral 2-channel digital storage oscilloscope is self triggered, auto scaling and auto ranging, and is equipped with a time-base optimising algorithm. The generator section features DSP technology to provide the high­ est quality signal accuracy and clar­ ity and delivers crystal controlled pure sine wave (20Hz to 100kHz), square wave, white/pink noise, multi-tone and warbled signals. The generator may be swept in frequen­cy and amplitude, with selectable start/stop and sweep parameters. A 400Hz high pass (hum and noise elimination) filter, 22Hz to 22kHz bandpass filter, and a CCIR 468-3 noise weighting filter are included as standard, together with a wow and flutter weighting filter. Other standard or custom filters are available on request. Measurement results are displayed on a 256 x 128 backlit graphics LCD display. Featuring large, easy to read characters, the display also provides dual bar graphs to display amplitude of the two input channels. Display scaling is auto­matically adjusted to the amplitude swing of the measured values. The oscilloscope displays two traces (original signal and residual) in the THD mode, or both input channels otherwise. An inbuilt Centronics interface provides output to a wide variety of standard printers. The optional RS232 serial interface facilitates full remote control of the A2 from a PC, employing Neutrik's AS03 control software. Designed to run on IBM XT, AT and compatible computers, the AS03 software provides en­hanced measurement functions for the A2 Audio Test & Service Sys­tem. AS03 features a window con­trolled user interface with mouse support on-line help for ease of operation. For further information, contact Amber Technology Pty Ltd, Unit B, 5 Skyline Place, Frenchs Forest, 2086. Phone (02) 975 1211. June 1994  89 1GHz digital real time oscilloscope Tektronix has announced the world’s first 1GHz Digital Real Time (DRT) oscilloscope, the TDS684A. The TDS684A’s real­time data acquisition capability stems from its use of proprietary sampling technology, which ena­ bles the scope to sample data at 5 gigasamples/second on all four channels showing input waveforms exceeding 50Hz without envelope effects is standard. Chart output is by a 200mm thermal array, which can record input signals or reprint memory data in A4 or A5 size for hard copy filing or transmission by fax. Data logging without chart output beyond the ORP1200s' internal 128Kb per channel is possi­ble by logging the captured data to the standard 1.44Mb floppy disk. Data is stored in MSDOS format, and can be read by most PC compatible comput­ ers, or reviewed on the ORM1200s' screen. For further information, contact Yokogawa Australia. Pty Ltd, Centrecourt D3, 25-27 Paul St, North Ryde, NSW 2113. Phone (02) 805 0699 or fax (02) 888 1844. Deluxe car sound system from Kenwood Kenwood has released the System X905, comprising the X905 cassette­ tuner with CD control, P705 Digital Signal Processor and C705 Multiple CD player. 90  Silicon Chip simultaneously. This per­mits the TDS684A to capture highly complex, non-repetitive sig­nal events associated with ad­vanced digital systems at the scope’s full 1GHz bandwidth. The TDS684A achieves its 1GHz performance without any compromises. With its 15,000 points record length, the scope can ac­quire up to 3 microseconds of data at the The heart of the system is the X905 cassette-tuner CD changer controller that controls up to two C705 multiple CD players plus other Kenwood products that incorporate the company's proprietary "Bus Line System" or K-Bus connection. The P705 Digital Signal Processor offers the effects of Concert Hall, Jazz Club, Stadium, Dance Hall, Church and Surround, recreating the ambi­ence of these large venues within the confines of a car. Front and rear chan­nels can also be individually adjusted for the correct ‘surround’ level. One touch selection of equalisation curves allows for pops, loudness, vocals, live house, classic or flat. fastest sweep speed. Full performance is available at all am­plitude settings and input imped­ances. In addition, the TDS684A provides 25 automatic measure­ ments and better than 50 pico­second measurement accuracy for swift, accurate measurement of sig­nal parameters. The TDS684A also has the full range of features provided by its predecessor, the Tektronix TDS644A digitising oscilloscope, including a high-resolution NuColor (TM) monitor for easy viewing of multiple waveforms and associated measurements and parameters. A graphical user interface that incor­ porates more than 100 different icons to make the TDS684A’s ca­ pabilities easy to learn and use; Tektronix’ proprietary Tristar (TM) digital signal processor for performing waveform maths in real time, including FFT; plus exten­sive date documentation capabili­ties, including the ability to store waveforms on a 3.5-inch DOS for­mat floppy disc in a number of standard desktop publishing for­mats. The third component in this sys­tem is the C705 which Kenwood claims to be the world's smallest 10 disc CD player. The C705 uses 1-bit DAC technology and employs the com­pany's proprietary CPDC or Clear Pulse Drive Circuitry. The C705 is designed for boot installation and can be mounted in a vertical or horizontal position. The System X905 can be bought as a system or as individual components: X905 cassette-tuner/CD controller, RRP $1499, P705 Digital Signal Proc­ essor, RRP $1199 and the C705 Multi­ple CD Player, RRP $1099. For further information and your nearest Ken­wood dealer, phone (008) 066 190. 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. Solar panel tracking project wanted Many thanks for an informative and interesting magazine but there are a couple of projects I would like to see. First, how about a design for a solar tracker, a device to keep a solar panel array always pointing at the sun for maximum efficiency? A number of articles have appeared for solar regulators but none for a tracker. The solar tracker is of great interest as I use a small panel to keep the batteries of a powered glider charged. A device of this type would make better use of the panel and the available sun. The mechanics, of course, would have to be left to the individual application. Next, I need a device to allow an additional battery in a caravan or campervan to be charged off the vehicle alternator but not to be discharged through the normal car electrics. My last request is for a high power DC motor speed con­troller with adjustable current limiting. Again, it is the prin­ciple of the electronics I am looking for with a design say for 24 TV viewing timer wanted I am one of those rare people who does not own a TV set but I am soon to acquire one. What I am concerned about is that I may become a TV glutton, at least in the first few months, and I may spend too much time with it. I’d like a TV timer so that I can ration my viewing to some sensible time per week, say 10 hours. Surely, such a timer could also be valuable for parents who want to ration their childrens’ viewing time. Can you help me? (D. C., Newtown, Tas). • Our first reaction, jaded as we all are by TV programs which bore even the most brain-damaged viewers, is that you don’t have a volts at 50 amps but able to be scaled up for higher voltage and current by the addition of more output FETs. This is to be used to provide some hill levelling for a recumbent trike. (C. W., Leumeah, NSW). • Thanks for your project suggestions. We will put them on the list of things to do. We did publish a high current speed con­trol, albeit without current limiting (difficult to provide in a high current design) in the November 1992 issue. That issue has sold out; however, we can provide a photocopy of the article for $7.00, including postage and handling. Adding a stereo blend control I have my stereo VCR hooked up to my hifi system and often watch movies using high quality headphones. Sound-wise this is great, except that the stereo image often seems absurdly wide, with action only inches apart on screen coming from hard left or right. I solved the problem by connecting a 100kΩ single-gang linear pot across the stereo channels, giving me infinitely problem. After a few weeks you will quickly come to the conclu­ sion that most programs are worthy of being missed. In fact, you will probably start to hanker for something worth­ while watching on most nights. As far as a TV timer for children is concerned, it would probably have to be wired permanently into the TV set, possibly into the antenna circuit, so that it could not be easily by­passed. However, this could be a problem when parents want to watch the set and they probably would need a keyswitch to override the circuit. Maybe our readers think the idea has merit and if they write and tell us, we might consider designing a suitable project. variable blending: full stereo at one extreme, full mono at the other. With a little careful adjustment the problem is completely solved. I was able to fit the pot to the front panel of the amplifier, giving me stereo blend control over all inputs. (I also wired it through an on/off switch but this is an unneces­sary luxury.) Those unable to modify their amplifiers may be able to rethink the idea to suit themselves. (P. P., Gorokan, NSW). Inverter driven power amplifiers I am doing my HSC this year and one of my subjects is elec­tronics. For this subject, I have to construct and produce a major project which will go towards my final mark and is worth 60% of the assessment. Part of what I am making is a power supply for a 100W + 100W amplifier which uses an input of 12V and gives out an output of ±30-40V. I was doing a bit of research through your magazines and found an inverter with the required specifications in the Decem­ber 1990 issue but it can only power a 50W + 50W amplifier or a single 100W amp. I was thinking of putting the amplifiers in parallel to the inverter but I found out that there wasn’t enough current to work it. So I was wondering if you could tell me how to increase the current or perhaps you could give me a new design to work the 100W + 100W amplifier. (A. S., Bexley, NSW). • As far as the 12V to ±50V DC-DC Converter is concerned, its main limiting factor is the high frequency transformer T1. There is really no way of upgrading the circuit without totally redesigning it. On the other hand, you could run two 100 watt amplifiers from it and gamble on the fact that if normal music signals are being handled, the inverter will seldom, if ever, be run into overload. You could improve the short term power delivery from the inverter by providing more output capacitance; June 1994  91 Photographic timer project wanted I am looking for an exposure meter for use with an enlarger in my darkroom. I have found that, with the cost of b&w paper at $1.00 for a 10 x 8 print (not including chemicals), “duds” are becoming a financial burden! There are some commercial units around and they seem to start at $170 plus tax and then go upwards if you want colour! One company markets a unit that is integrated into a timer for the enlarger: you set the exposure and time in a single opera­tion. I realise that the problem is going to be calibration for the various paper sensitivities and I can’t find out what these figures are. There seem to be no “ASA” ratings for paper. I haven’t seen any photographic circuits published for a while, so this may be a good project for the future. I’ve enclosed a cir­cuit of the timer I’m starting to build. It’s based on a 555 IC and I’m think- ie, in parallel with the existing 1000µF 63VW capacitors. On the other hand, if you really did want an inverter to deliver more power, you could start with our 12V to 240VAC 200W design featured in the February 1994 issue. You would omit the square wave generator section altogether and change the secondary winding and rectifier arrangement so that the inverter delivered the required ±50V DC. Even so, there would be quite a lot of work in reworking this design and if you can get away with the existing 100W inverter, it will be much more straightforward and probably cheaper. Capacitance meter does detect leaky elec­tros About a year ago, we built the Digital Capacitance Meter (SILICON CHIP, May 1990) for use in repairing monitors and switchmode power supplies and it is giving us some cause for concern. In some cases we have taken capacitors out of a circuit board (say 47µF) and checked it with your meter which would read it OK (say 47µF). But when 92  Silicon Chip ing of changing the timer pot to a 100kΩ 40 “click” pot from DSE. This would mean that each click would give 2.5 seconds. I have chosen to use a relay instead of an opto-coupler/Triac because I don’t have 240VAC mains power. My design will eventually need two relays, a small one to drive a heavy duty one that will switch a 12V lamp in the enlarger. I hope that you can give me some help in this matter, even if this means recommending another source of information. (D.H., Bee­ ch­­wood, NSW). • We have not published any circuits for a phototimer. Your approach using a 555 seems reasonable but the 40 click pot may not be very accurate, particularly at the extremes of rotation where moving the knob by a click may result in no change in resistance setting. You would be better off using a 12-position switch and individual resistors, with perhaps an additional switch to provide more ranges. it was put back into the circuit board, nothing would work. Eventually, we would check the capacitor on a commercial capacitance meter and this would indicate a value of, say, 3µF. Replacing the capacitor cured the problem. On non electro­lytics, your meter works fine and when the elec­trolytics are new it also works fine. I have included two of these elusive capacitors for your evalua­ tion. The 33µF measures 31µF on your meter but on a commercial capacitance meter it is 4.6µF; the 10µF measures 8.6µF on yours, but 0.55µF on the other. The lower values appear to be the cor­rect value. Your reply would be most welcome. (A. L., Perth, WA). • The discrepancies between the value of capacitance read on the SILICON CHIP meter and the commercial meter are caused by the method used by each meter to read capacitance. The capacitors that you have supplied are “leaky”, meaning that they have a low value of resistance across the capacitor. If the capacitance meter provides a high current to the capacitor during measure­ment, the leakage resistance will be swamped by the current and thus the capacitor value will read normally. Other capacitance meters may read capacitance using a lower current and thus the capacitance value will be affected by the capacitor’s leakage resistance. The SILICON CHIP Digital Capacitance Meter can be used to detect leaky capacitors by comparing the values measured on each range. Each range change alters the current supplied to the capacitor by a factor of 10 so if the capacitance reading diff­ers markedly between ranges, then the capacitor should be regard­ed as suspect. For example, the leaky 10µF capac­ itor that you supplied reads 0.0µF on the 9999µF range, 5.1µF on the 999.9µF range and 8.66µF on the 99.99µF range. The leaky 33µF capac­ itor reads 18µF on the 9999µF range, 26.8µF on the 999.9µF range and 31.05µF on the 99.99µF range. By contrast a good (ie, low leakage) 47µF capacitor reads 48µF on the 9999µF range, 47.0µF on the 999.9µF range and 47.6µF on the 99.99µF range. Really, to properly test electrolytic capacitors, you need a bridge which measures leakage and power factor, as well as capacitance, while applying the rated voltage. In the meantime, if you have an electro which is suspect, try measuring it on two or three ranges. If the value differs markedly from range to range, ditch the capacitor. Problems with stepper motor software I have constructed the Stepping Motor Controller as per SILICON CHIP in the January 1994 issue and it works perfectly. Are there books available about home robotics and how to program them using Q Basic? I have printed and read the “READ.ME” file. The printing must have been a fluke because I cannot repeat the printing operation. Now there is only a “bleep”. My computer is an IBM compatible. A copy of “C, How To Program” was obtained, but one import­ant and basic instruction is missing, that is, how to “C” on an IBM computer. Does one have to obtain software to program the computer? Please do not say “use a compiler” without an explana­tion. (A. W., Elwood, Vic). • We are glad that your stepper motor controller is working well. There may be books on home robotics available but we are unable to help you on this point. Normally, you should be able to print the READ.ME file by typing “COPY READ.ME LPT1” and then ENTER. If you can no longer do this and you can no longer read the file using the TYPE command, it suggests that the file has been corrupted. If you wish to run a program written in C on your computer, you must have a C compiler, such as Turbo-C or Turbo-C++ by Borland in order to run it. All programs, no matter what language they are written in, require an interpreter (such as is used in the Basic package on your machine) or a compiler. Programs writ­ten in C do not run using interpreters so a compiler is the only way. In effect, a compiler converts high level language to ma­chine language which can be “understood” by the microprocessor. Needs circuit for a BWD scope I am writing to you in the hope you or one of my fellow readers can help me. I have a BWD 539D oscilloscope which is out of order and need a circuit diagram. I need to know where I can get in touch with the distributors, or if any reader could help with a copy or the original service manual for which I would be happy to pay. (Bob Riding, 65 Pacific Bay, Fingal Bay, NSW 2315). Notes & Errata Remote Control Extender for VCR’s; April 1994: the panel mount DC socket for the plugpack should be an insulating type to prevent the negative pin shorting to the case. This is shown in the photograph on page 21 of the article in the April issue. Induction Balance Metal Locator; May 1994: The parts list should indicate 5 rather than 4 0.1µF MKT capacitors. The extra capaci­tor is shown on the overlay but not on the circuit. It is used as a bypass to ground for the +7V supply near VR1. The .001µF ca­ pacitor shown on the overlay next to VR1 should be .01µF. Champ Audio Amplifier; February 1994: the text on page 47 regard­ing the “blurt” test should read “You do this by winding the trimpot anticlockwise and then putting your finger on the input”. SC The Emperor’s New Clothes: from page 29 understanding. Many idiosyncratic system behaviours that plague us are actually cracks in the thin veneer of standards compliance infrastructure through which the designers actual implementation shows through. It’s a bit like catching a glimpse of the puppeteer pulling the strings behind the ‘Punch & Judy’ show. Second, people take short cuts. Ever noticed how some of your old software suddenly stopped working when you compressed your hard drive with Dos 6.2? All those programmers were too clever by half and decided to bypass the service routines provid­ed and run their own show. The tendency to take short cuts is partly due to the unseemly haste with which products have to be brought to a fad driven market and partly due to a basic flaw in human nature. It goes something like this. A committee (a group hell bent on detailing the creation out the door, there isn’t much motivation for anyone to tidy up the blueprint. So what do you do if you see a “dinner retrieval kit com­plete with burger cam”? Ask yourself the question, “Do I really need this?” If yes, then comes, “Have I seen one of these actual­ ly working in the real world?” If no, then “What background do my associates and I have with this technology”. If you actually purchase the thing, unwrap it very careful­ly. That way you can always put stuff back just like it was when you can’t get it to perform. Now return it and make out like you never really had time to try it anyway. Act casual, disinterested even. Popular culture dictates the more aloof and distant you are, the more in control you must be. If they get stroppy, remind them about current consumer legislation regarding the onus to source goods of merchand­ isable (read: it should work) quality. The Emperor’s new clothes are indeed magnificent. Not only are they grand but they are mix and match. “The tendency to take short cuts is partly due to the unseemly haste with which products have to be brought to a fad driven market and partly due to a basic flaw in human nature.” a camel when the specification calls for a horse) decides on a procedure or protocol, an agreed way of doing things. Before they have even finished their deliberations, usually, the wider community of participants has figured out a better way of doing things. If the new way is really spiffy, everyone just ignores what the committee says and the improved approach becomes the de facto standard. But often the new approach is more human ego than efficacy. It’s a little bit better or just a bit quicker, con­formity sacrificed on the altar of that perverse human need to “do it my way”. Lastly, there is the problem of documentation. This relates again to the factors mentioned previously, human nature and haste. Most design teams start out with a blueprint of what they want. They build it and it doesn’t work. So they spend ages tinkering with the entrails until it does work. Then in the frantic scramble to get “This goes with that,” all inter-connectable, compatible and groovy because of the underlying open architecture of structure and function. Everyone agrees that it must be so. The collective will of all those people makes it the case. I rest my case. I scanned in a little pic for this article but the scanner software won’t load it today. It loaded fine yesterday. But then I’ve done a tape backup in the interim. I really do use my scanner and tape backup so I’ll have to pursue the issue. Of course, the suppliers can’t help so I’m on my own again. Mind you, I’m lucky this time, I think I know what’s actually going on with this one. I should have it sorted in SC no time. *Kris McLean is the principal of McLean Automation, a firm special­ is­ing in data transfer technology. June 1994  93 MARKET CENTRE Cash in your surplus gear. Advertise it here in Silicon Chip. FOR SALE THE HOMEBUILT DYNAMO: (plans) brushless, 1000 DC watt at 740 revs. $A85 postpaid airmail from Al Forbes, PO Box 3919 - SC, Auckland, NZ. Phone Auckland (09) 818 8967 any time. Rotor magnets (3700 gauss) kit now available. FLUORESCENT INVERTER KIT (SC Feb 91) 12V or 24V/5W-21W.48V ver­sion on request. Secondary wind, board plus components $30.00 plus P&P $4.00. Fluorescent inverter kit (SC Nov 93) 12V/24V/48V, 18W and 38W P.O.A. Solar battery charging regulator short form kit 12V or 24V (series) (SC Jan 94) employs Mosfet to switch solar array max current 10A $54.00 plus p&p $4.00. Additional Mosfet $8.00 and Schottky diode $5.00 to make 20A regulator. Cheques and postal money orders accepted with mail orders. Send orders to Otakar Priboj, PO Box 362, CLASSIFIED ADVERTISING RATES 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. _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ Villawood, NSW 2163, Austra­lia. Phone (02) 724 3801. SOUTHERN CROSS SBC, accessories & EPROM emulator. See SC 8/93 & 12/93. Ideal for TAFE, schools & individual use. Alpine Technolo­gies, tel/fax (03) 751 1989. NETWORK YOUR PCs with “Little Big LAN”. Share disk drives and files (multi-user record locking), CD-ROMs and printers (with spooling). Connect PCs via serial or parallel ports, Arcnet and/or Ethernet cards. Supports up to 250 computers per network for only $95 ($100 for 3.5") for a whole network. Add $3 for postage in Australia. Works with MS-DOS, DR-DOS and Windows. For more information, write to GRAN­ TRONICS, PO Box 275, Wentworth­ville 2145. Phone A/H (02) 631 1236. A TRUE AUSSIE Z80 Development System driven from MS-DOS LPT1: EPROM is emulated during development. PCB and disk full of Source Code, Z8T XASM, Z8TBasic, and full circuits. $38. With EPROM $52. Promo disk $2. Don McKenzie, 29 Ellesmere Crescent, Tullamarine, Vic 3043. Phone (03) 338 6286. WEATHER FAX programs for IBM XT/ ATs *** “RADFAX2” $35 is a high resolution, shortwave weather fax, Morse & Rtty receiving program. Suitable for CGA, EGA, VGA and Hercules cards. Needs SSB HF radio & Radfax decoder. 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 Radio and Electrical Books 1914 Catalog Electro Importing Co ............$18 1936 Radio Data Book ...............................$15 Hammarlund Short Wave Manual (1937)....$11 Henley’s 222 Radio Circuit Designs ......$26.50 Neon Signs (1935) ................................$28.50 How to Become a Radio Amateur (1930) .....$7 How to Build & Operate Short Wave Receivers ...................................................$18 How to Build a Solar Cell ...........................$11 High Frequency Apparatus (1916) .............$29 Radio for Beginners ................................$6.50 Radio for the Millions .................................$20 Short Wave Radio Manual (1934) ..............$30 Television (1938) .........................................$7 Tesla Coil ....................................................$11 Tesla Coil Secrets .......................................$16 Tesla Said ...................................................$79 Construction of Large Induction Coils ........$23 The Wimshurst Machine How to Make .$19.50 The Wireless Man ......................................$27 Wireless Experimenter’s Manual 1920 .......$31 Electrical Goods & Radio Apparatus ..........$14 Electroplating (1911) ............................$17.75 Experimental Television How to Make ........$34 Meissner “How to Build” Instructions ........$22 How & Why of Radio Apparatus ...........$20.50 All prices include postage. Payment can be made by cheque or money order made out to Plough Book Sales, PO Box 14, Belmont, Vic. 3216. Phone (052) 66 1262. Silicon Supply and Manufacturing 4002B 4010B 4011B 4012B 4013B 4014B 40150 4017B 4019B 4023B 4025B 4027B 4040B 4048B 4050B 4053B 4060B 4069B 4070B 4071B 4075B 4082B 4094B 74HC11 74HC27 .86 .70 .86 .77 .82 1.53 1.55 1.88 .82 .67 .67 .67 2.13 1.15 .77 1.39 1.71 .69 .69 .69 .69 .69 1.31 .55 .50 74HC30 74HC76 74HC86 74LS11 74LS12 74LS13 74LS14 74LS20 74LS21 74LS27 74LS30 74LS33 74LS49 74LS73 74LS74 74LS83 74LS85 74LS90 74LS92 74LS109 74LS126 74LS138 74LS139 74LS147 74LS148 .50 .65 .55 .60 .60 1.00 .65 .65 .50 .50 .50 .60 2.85 1.35 .55 .90 .75 1.10 1.45 1.10 .60 .75 .75 2.85 1.25 74LS151 74HC138 74HC139 74HC154 74HC174 74HC373 74F00 74F02 74F08 74F10 74F11 74F20 74F30 74F32 74F36 74F38 74F151 74F163 74F169 74F175 74F241 74F244 74F257 74F258 74F353 .60 1.05 .60 3.80 .80 1.25 .50 .50 .50 .50 .50 .50 .50 .50 1.10 .80 .65 .85 2.30 .80 1.15 1.10 .75 2.15 1.75 All prices include sales tax. Phone (02) 554 3114; Fax (02) 554 9374. After hours only bulletin board on (02) 554 3114 (Ringback). Let the modem ring twice, hang-up, redial the BBS number, modem answers on second call. PO Box 92, Bexley North, NSW 2207. TRANSFORMER REWINDS ALL TYPES OF TRANSFORMER REWINDS *** “SATFAX” $45 is a NOAA, Meteor & GMS weather satellite picture receiving program. Needs EGA or VGA plus “WEATHER FAX” PC card. *** “MAXISAT” $75 is similar to SATFAX but needs 2Mb expanded memory (EMS 3.6 or 4.0) and 1024 x 768 SVGA card. All programs are on 5.25-inch or 3.5-inch disks (state which) & include documentation. Add $3 postage. Only from M. Delahunty, 42 Villiers St, New Farm, Qld 4005. Phone (07) 358 2785. REAL TIME ICE!!! The only way to go. MOTOROLA 6805 EMULATOR and programmers. Prices and data from Graham Blowes, Mantis Micro Products, 38 Garnet Street, Niddrie 3042. Phone (03) 337 1917 (a/h), (03) 575 3349 (b/h). Fax (03) 575 3369. BINARY CLOCK - OCTOBER 1993: complete documentation supplied, includes introduction to binary, how it works, PLD source list­ings, conversion tables. Kit with PCB and all components $75 + $5 p&p. Optional Z frame stand (includes spacers and chassis DC connector) $25 + $5 p&p. Prototype Electronics, 1/29 Stewart St, Parra­ matta, NSW 2124. Phone (02) 683 3510; Fax TRANSFORMER REWINDS Reply Paid No.7, PO Box 1058, St Marys, NSW 2760. Ph: (02) 833 1146. Fax: (02) 623 5559. SECONTRONICS COMPONENTS, COMPUTERS, ELECTRON TUBES S/H TEST EQUIPMENT, COMPUTER REPAIRS PC COMPATIBLE KEYBOARDS 101 AT:$39 I/O + IDE/FDD $35 RECYCLED EPROMS AT I/O CARDS $22 2716 $1.50 2SD1169 $2.00 2732 $1.50 2N3440 $0.80 2764 $2.00 2N3439 $0.80 27128 $3.00 2SC3157 $4.00 27256 $3.50 27C41 $0.80 27512 $3.50 7406 $0.20 27C101 $4.00 8250 $5     8251 $2 8259 $2    6809 $8 MC8050 $2 MCT275 $1.20 MOC3032  $2 VALVES: QQV07/50 $25 3D21   $8 12AU7   $6 6SG7   $8 6U8A   $8 1S2   $3 1T4   $6 CV553   $3 2C39A $30 2C40A $40 3A4   $8 5651   $6 5651A   $6 6AK5   $6 6J6WA  $7 6AM6  $5 6BA6  $4 SPECIAL: SURFACE MOUNT COMPONENT PACK – 180 RESISTORS, 40 ZENERS, 30 TRANSISTORS AND 2 ICs. $6.50 INC. PACK & POST PHONE OR MAIL ORDERS, CREDIT CARDS ACCEPTED FOR ORDERS $20 & OVER, DISCOUNTS FOR QUANTITY ORDERS. NOW AT SHOP 5, 79 RICKSTON ST, MANLEY WEST, QLD. 4179. OPEN TUES - FRID 9.30AM - 5PM, SAT. 9AM - 2PM. MAIL ORDERS TO PO BOX 34 CANNON HILL QLD. 4170. PHONE (07) 396 1859, FAX (07) 855 1014. MEMORY PRICES PRICES AT APRIL 8TH, 1994 SIMM 1Mb x 3 1Mb x 9 4Mb x 9 4Mb (72-pin) 8Mb (72-pin) 16Mb (72-pin) 70ns 70ns 70ns 70ns 70ns 70ns $63 $65 $256 $250 $520 $985 DRAM DIP 1 x 1Mb 256 x 4 70ns 70ns $8.50 $9.00 IBM PS.2 55/65SXVP L40/N33 90/95 PS1 4Mb 4Mb 4Mb $250 $300 $265 MAC 4Mb 4Mb x 80 80ns 6Mb P’BOOK $220 $380 CO-PROCESSORS 387S/DX to 40 $105 LASER PRINTER HP with 4Mb $260 COMPAQ PROLINEA 8Mb $520 TOSHIBA 2000SX 8Mb $475 46/1900 3.3 4Mb $350 SUN SPARC 10/20 16Mb $1140 PCMCIA 1Mb V2 BAT SRAM $230 2Mb V2 BAT SRAM $380 2Mb V2 FLSH SRAM $380 42Mb V2 HARD DRIVE $560 Sales tax 21%. Overnight delivery. Credit cards welcome. 5-Year Warranty Ring for Latest Prices 1st Floor, 100 Yarrara Rd, PO Box 382, Pennant Hills, 2120. Tel: (02) 980 6988 Fax: (02) 980 6991 (02) 630 3148. Pay by cheque, money order, credit card. SOFTWARE: T Calculator $15; Calculator VGA $25; T Caltcal VGA $30; Parts Data Base $30; Addresses Data Base $30; Accounts Data Base $30; Word processor $35; Micro PCB $40; Zeusplb $150; Sche­matics $110. These are not shareware for information on any program send a $4 postage fee. To order, add $5 and send cheque or money order payable to: G. A. Georgopoulos, 34 Scouller St, Marrickville, NSW 2204. SUBSTITUTE FOR A HANDFUL OF ICs: Parallax “BASIC STAMP”. A gen­er­al purpose small circuit module, it is really a 25 x 50mm board with a computer chip (4MHz PIC 16C56), EE- PELHAM PROM, 8 I/O pins, board space includes prototyping area. Program it on a PC (only 33 instructions) with development kit which includes one “BASIC STAMP” ($249 plus S/T & post), extra modules ($66 plus S/T & post). Send 45c stamp for more information. Parallax distributor and techni­cal support in Australia: MicroZed Computers, PO Box 634, Armi­dale, NSW 2350. Facsimile (067) 72 8987. UNUSUAL BOOKS: Electronic Devices, Fireworks, Locksmithing, Radar Invisibility, Surveillance, Self-Protection, Unusual Chem­ istry and more. For a complete catalog, send 95 cents in stamps to Vector Press, Dept S, PO Box 434, Brighton, SA 5048. June 1994  95 200 Watt Power MOSFET Amplifier Module As published in the June 1994 issue of Silicon Chip. $159 per kit for Bankcard, Master Card or Visa Card Orders; $149 per kit for cheque or money order. Also fully assembled and tested kits for $199 each. Power supplies and cases available for the amplifier module if required. Postage and handling $8; 3kg overnight airbag for anywhere within Australia $10. Computer & Electronic Services Pty Ltd 27 Osborne Avenue, Trevallyn Launceston, Tasmania 7250 Phone (003) 34 4218; Fax (003) 31 4328; Mobile (018) 13 3979    Zelcon Technic Pty Ltd • • • • PCB Supplier Photoplotting Services SMT/Through-Hole Assembly CAD facilitites PO Box 149, Glenorchy, Tas 7010 Ph: (002) 71 8120, Fax: (002) 71 8182 BBS: (002) 73 0799 68705 DEVELOPMENT SYSTEM: In Circuit Simulator/Emulator and pro­ grammer board. Supports 68HC705C8/ C4/J2/K1, 68705P3/U3/R3 micro controllers and more. Contact Robert Priestley, PO 38/4 Illawong Village, Fowler Road, Illawong 2234. Phone (018) 02 0481; Fax (02) 541 0734. KIT REPAIRS and assembly. All work guaranteed. Phone (047) 51 5620 MICASOFT Electronics and Computing tutor program, written in UK, ideal for TAFE, schools, or individual use. Now available in Australia. Send $1.80 in stamps for demo disk (tell us what size). MicroZed Computers, PO Box 634, Armidale 2350. IC R7100 ICOM Communications Receiver new in box; perfect condi­tion; cost $2600, sell $2000. Alan (043) 24 2296. PRINTED CIRCUIT BOARDS for the hobbyist. For service & enquiries contact: T. A. Mowles (08) 326 5590. EPROM & SRAM EMULATOR: 2K x 8 (or 16) to 6K x 8 (or 16). Download and verify via standard PC printer port. Supports Binary, Intel and Motorola hex formats. Includes Binary Editor. 96  Silicon Chip CTOAN ELECTRONICS 4-channel piped music system for your home. Hundreds of dollars cheaper than commercial systems. Build it yourself and save heaps. Ring for details. PO Box 211, Jimboomba 4280. Phone (07) 297 5421. Advertising Index Altronics ................................ 26-28 Antique Radio Restorations.........94 Av-Comm.....................................57 Computer & Electr. Services........96 Ctoan Electronics........................96 RETAIL OPPORTUNITIES NEW ZEALAND David Reid Electronics ..............67 Dick Smith Electronics........... 12-13 Electronic Fault Info.....................43 Harbuch Electronics....................67 Instant PCBs................................95 Jaycar Electronics (Australia) is looking to expand its service to NZ customers by appointing key resellers in that country. If you have a business which you think would benefit by reselling Jaycar products, please contact us. We are particularly interested in retail establishments which are already in the electronic hobby area. This is not to exclude TV/video service, camera stores or other businesses which are related to the sale of technical products. For more information, contact: Bruce Routley,PO Box 185, Concord, NSW 2137, Australia. Fax 612 743 2066. For more information, contact Northern Digital, PO Box 1252, Collingwood, Vic 3066. Fax/Ph (03) 484 5133. WANTED CIRCUIT DIAGRAM for clock/radio/TV ‘Superstar’ model TCR-1001 (11cm TV). Phone (03) 793 3104 WANTED TO BUY buy or borrow: programmers reference manual for Tek­tronics Plotter 4662. Phone (099) 38 1899. ANTIQUE RADIO ANTIQUE RADIO RESTORATIONS: specialist restoration service provided for vintage radios, test equipment & sales. Service includes chassis rewiring, recon­ densering, valve testing & me­ chanical re­­furbishment. Rejuvenation of wooden, bakelite & metal cabinets. Plenty of parts – require details for mail order. About 1200 radios within 16,000 square feet. Two-year warranty on full restoration. Open on Saturday 10am4.30pm; Sunday 12.30-4.30pm. 109 Cann St, Bass Hill, NSW 2197. Phone (02) 645 3173 BH or (02) 726 1613 AH. Jaycar .............................. 45-52,96 L & M Video...................................5 Macservice..................................35 Oatley Electronics.................. 60-61 PC Computers.............................65 Pelham........................................95 Plough Book Sales......................95 RCS Radio ..................................94 Resurrection Radio......................83 Rod Irving Electronics .......... 75-79 Secontronics................................95 Silicon Chip Back Issues....... 86-87 Silicon Chip Binders..................IBC Silicon Chip Projects Book......OBC Silicon Chip Software..................39 Silicon Supply & Manufact...........95 Transformer Rewinds...................95 West Tech Industries.................IFC Wombat Electronics.....................73 Yuga Enterprise...........................73 Zelcon Technic Pty Ltd.................96 _________________________________ 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. • H. T. Electronics, 35 Valley View Crescent, Hackham West, SA 5163. Phone (08) 326 5590.