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WHAT TO DO WHEN YOUR COMPUTER GOES BUNG SERVICING - VINTAGE RADIO - COMPUTERS - AMATEUR RADIO - PROJECTS 1ii 0 D. .... .!!! ;g ' MULTI-SECTOR BURGLAR ALARM ~CJ) -0. C/l ID ,iZ ~~ 'O C: !~ a, Ol .iC'>.C ~ a, :::J a: D. *Low noise universal stereo preamplifier *Load protection switch for power supplies FITTING A TO YOUR COMPUTER increased airflow and quiet with particularly favourable airflow/noise characteristics for sensitive audibility requirements. Papst first for Reliability Versatility - Availability. uty, rectangular Harting are renowned as market leaders. Weco are specialists in the manufacture of terminal blocks with a range of over 10,000 products. These include Connectors for printed circuits, Terminal Strips and Tab Connectors for Panel/ chassis mounting, ceramic terminal blocks including Explosion and Firedamp, proof types. Recent developments have been a range of Electronic Modules for use on mounting rails to DIN EN 50022-035 and 045. Also the new series 120 and 150 Multilift screw connectors for printed circuits featuring lift terminals that guarantee high pressure contacts and allow countless wire disconnections. (wEco°j Since 1949 Methode have been providing reliable, cost effective interconnection products for use in Military, Aerospace, Computer Telecommunication, Industrial and Automatic applications. Their product range includes single and dual row headers and connectors for wire to board and board to board interconnections, insulation displacement connectors, pin and socket connectors, card edge connectors and other special products. A new range of Microcircuit Sockets, PLCC and SIM/SIP have been introduced for through board and surface mount applications. Wilhelm Westermann are recognised as th e world leader in the development and manufacture of miniturised plastic film capacitors. Materials used incl ude polyester, polycarbonate, polypropylene and th e new polyphenylene sulfide for high frequency applications. In addition th eir MP3, Metallised Paper, Capacitors are internationally approved for use across the mains in RFI suppression applications. These units are superior to capacitors with th ermo plastic film dielectrics due to th eir high corona inception level and they have excellent active and passive flame retardent properties Adilam Electronics~: The Component Specialists DISTRIBlJTORS : I Rectron have been manufacturing a broad range of rectifer products since 1976. Their range now includes Standard, Schottky Barrier, Fast, High Efficiency, High Voltage, Automotive and Surface Mounting rectifer diodes. The bridge rectifier range extends from 1 Amp to 35 Amp with a PIV to 1000 Volts. Various package configurations are available including OIL, SIL and industry standard formats with wire or tab terminals. MELBOURNE- SYDNEY- Suite 7, 145 Parker Street, Templestowe 3106 PO Box 131, Bulleen 3105 T~lephone: (03) 846 2511 Facsimile: (03) 846 1467 Suite 1, Ramsgate Plaza, 191 Ramsgate Road, Sans Souc i 22 19 Telephone: (02) 529 22 77 Facsimile: (02) 529 5893 ADELAIDE : N.S. Electronics Ph: (08) 46 8 531 Fax : (08) 340 1456 BRISBANE: St. Lucia Electronics Ph · (0 7) 252 7466 Fa x· (0 7) 252 28 62 PERTH: Pro-spec <:c: - ors Ph: {09 ) 36~ 7592 =ax. 9 3,-! · - 59 2 JUNE 1990 FEATURES PROTECT YOUR HOME with this new alarm circuit. It features variable exit & entry delays, alarm driver circuitry, & independent sector inputs. Construction starts on page 30. 4 Off-Shore Oil Platforms by Bryan Maher A look at how they work 18 Fitting A Fax Card To Your PC by Jennifer Bonnitcha Viemar System's Fax89 - the pros & cons 76 The Technology Letters by Richard Kopf Fred Bloggs & Pathetic Technology PROJECTS TO BUILD 30 Multi-Sector Home Burglar Alarm by Greg Swain Electronic surveillance for your home 40 Universal Stereo Preamplifier by John Clarke WANT A FAX machine but can't justify the cost? A fax card that fits into your PC may be answer. Details page 18. Versatile preamp for magnetic cartride, tape head or microphone 60 A Speed Alarm For Your Car by Peter Gray Monitors three presettable speeds 66 Load Protector For Power Supplies by Leo Simpson Keeps dangerous voltages away from the load at switch-on SPECIAL COLUMNS 22 Vintage Radio by John Hill How to recognise AD/DC sets 50 Serviceman's Log by the TV serviceman You'll get a buzz out of this one 70 Computer Bits by Jennifer Bonnitcha What to do when your computer goes bung; Pt.2 84 Amateur Radio by Garry Cratt Understanding frequency modulation Silicon Chip has changed address SILICON CHIP has moved to new premises at Unit 39, 5 Ponderosa Pde, Warriewood, NSW 2102. Our phone number is now (02) 979 5644 while the fax number is (02) 979 6503. Our postal address remains PO Box 139, Collaroy Beach, NSW 2097. THE SERVICEMAN has one story on frame buzz this month and a nudder story on cows well, milking machines, actually. His stories start on page 50. 87 Remote Control by Bob Young Design factors for model aircraft DEPARTMENTS 2 Publisher's Letter 3 Mailbag 25 Bookshelf 56 Circuit Notebook 96 Product Showcase 100 Ask Silicon Chip 102 Notes & Errata 103 Market Centre 104 Subscription Page THIS UNIVERSAL preamplifier can be used with a magnetic cartridge, tape head or microphone. We show you how to build it starting page 40. JUNE 1990 1 Publisher & Editor-in-Chief Leo Simpson, B.Bus. Editor Greg Swain, B.Sc.(Hons.) Technical Staff John Clarke , B.E.(Elec.) Robert Flynn Advertising Manager Paul Buchtmann (02) 979 5644 Mobile: 018 28 5532 Victorian Representative McDonald Woodside & Associates Pty Ltd , 143a Como Parade East, Parkdale, Victoria 3194. Phone (03) 587 5155. Contact: Cameron McDonald. Regular Contributors Jennifer Bonnitcha, B.A. Garry Crall, VK2YBX John Hill Jim Lawler, MTETIA Bryan Maher, M.E., B.Sc . Jim Yalden, VK2YGY Darren Yates Bob Young Photography Bob Donaldson Editorial Advisory Panel Philip Watson, MIREE, VK2ZPW Norman Marks Steve Payor, B.Sc., B.E. SILICON CHIP is published 1 2 times a year by Silicon Chip Publications Pty Ltd. All material copyright (c). No part of the contents of this publication may be reproduced without prior written consent of the publisher. Typesetting: Magazine Printers Ply Ltd, Rozelle, NSW 2039. Printing: Macquarie Print, Dubbo , NSW 2830. Distribution: Network Distribution Company. Subscription rates: $42 per year in Australia. For overseas rates, refer to the subscription page in this issue. Liability: Devices or circuits described in SILICON CHIP may be covered by patents. SILICON CHIP disclaims any liability for the infringement of such patents by the manufacturing or selling of any such equipment. Editorial & advertising offices: Unit 39, 5 Ponderosa Pde, Warriewood , NSW 2102. Postal address: PO Box 139, Collaroy Beach, NSW 2097 . Phone (02) 979 5644. Fax (02) 979 6503. ISSN 1030-2662 2 SILICON CHIP PUBLISHER'S LETTER The big move: a new stage in our development By the time you read this issue, we should be established in our new premises in Warriewood, a northern beachside suburb of Sydney. For the staff of SILICON CHIP, it marks a big step forward in the development of the magazine. Up till now, we have had very cramped quarters in the downstairs area of my home. In the limited space available we have carried out all of our activities, in editorial preparation, circuit design, drafting, library and record storage, advertising sales, accounting, subscriptions and mail order, and so on. All of these activities, which are part and parcel of a magazine publishing company, have been carried on inside a proverbial sardine can. It will be great to spread out. Why have we waited so long before moving into larger premises? Well, we've been cautious. The best way to survive and grow when you are starting a business is to keep close control over costs. But there is a limit to how long you can do this and after a while it can stunt the growth of any company, publishing or otherwise. With your considerable support, both from readers and advertisers, we have established SILICON CHIP as Australia's most dynamic electronics magazine. When we started SILICON CHIP, there were four locally produced monthly consumer electronics magazines and quite a few foreign imports. Now there are just two Australian electronics magazines and not so many imports. So the time has come for us to move. In the short term, it won't make any visible difference to SILICON CHIP. We will continue to improve it gradually as more resources become available to us. In the long term though, it will enable us to serve you, the readers, much better. With your support, we will continue to grow strongly. By the way, while our premises and phone numbers have changed (with more lines), our postal address will remain the same, so there will be no interruption to the mail. Keep those letters coming in. They help keep us attuned to what you want to read about in SILICON CHIP. Leo Simpson Our new address: Unit 39, 5 Ponderosa Pde, Warriewood, NSW 2102. Phone (02) 979 5644. Fax (02) 979 6503. Our postal address remains: PO Box 139, Collaroy Beach, NSW 2097. MAILBAG Microwave ovens are suspect too! I read with interest the editorial in the April issue of your excellent magazine. After you had given many examples of modern scientific advances whose side effects become obvious all too late, I thought you were about to concede that microwave ovens may also have some undesirable aspects to them. Unfortunately, you did not. You may be an expert in the field of electronics and allied subjects but this does not give you the right to set yourself up as an authority on the cooking and digestion of foodstuffs as you have done. Now I claim no expert knowledge in these fields either, but I thought you should know that there are some who claim that microwave cooked food does have some serious problems and so I bring them to your attention. Apparently, microwaves can kill natural enzymes in food. This means that our bodies have to supply extra enzymes to break the food up during the digestive process. I feel that one should keep an open mind as to the possible long term effects of microwave cooked food. David Clarke Bongholme, Vic Comment: as we understand it (and not being experts on the chemistry of cooking), all cooking destroys many natural organisms in food, thereby making it edible and safe. According to most nutrition experts, cooking food in a microwave oven is safe. Active antenna can't outperform longwire antennas I read SILICON CHIP with interest and do like articles on improving radio reception. The article in the January issue entitled "Active Antenna for the Shortwave Bands" was interesting, however I found some of the claims for its performance quite extravagant and, I believe, unsupportable. I found the sentence "Because it can tune out interfering signals and noise, the World Tuner can outperform many longwire antennas" unbelievable. If this were so, all high grade HF communications receivers would be fitted with one as a matter of course. I haven't seen any fitted, and I work in the communications and interference/noise reduction industry. Devices such as this will help the performance of sets which lack sensitivity or where an outside antenna is impractical, or the owner is just too bone lazy to erect an efficient outside antenna. Many people seem to subscribe to the idea that small is beautiful - believe me, small is not beautiful when it applies to antennas. Within the normal domestic environment there are all sorts of noise and interference carried along the electrical wiring and it is radiated for some distance around it. TV line output noise will certainly be most troublesome with this device as the antenna is within the household electrical noise field. The device also responds to the electric component of the electromagnetic wave which has quite a high intensity in the " near field". A loop antenna responds to the magnetic component which has ~ much lower "near field" intensity. Therefore to get low noise, use a loop antenna not a whip antenna. For the above reason, I cannot see how this device can tune out interfering signals or noise. In addition, a whip antenna is omnidirectional and so cannot null out interfering signals and noise. I therefore ask you how does this device tune out interfering signals and noise'? As I see it, the advantages of such a unit are to provide better sensitivity for sets which are poor in this respect (there are plenty of those around), to improve signal to noise ratio if it has a better SIN ratio than the receiver it is connected to, or to provide a convenient small antenna where a larger antenna cannot be installed. However, it has a serious disadvantage in that its noise and interference performance will be decidedly inferior to that of an efficient, properly installed, outside antenna; and it will usually be more expensive. If an active antenna must be used in the manner that this one is intended to be, it must be said that it is SILICON CHIP, PO Box 139, Collaroy Beach 2097. cheaper than imported ones and should perform every bit as well. Serious shortwave listeners should not use one though. Rodney Champness Benalla, Vic Comment: since the Active Antenna incorporates a tunable bandpass filter, it will effectively remove strong out-ofband interference. As you suggest, it cannot remove in-band interference but then again, neither can a longwire antenna. More on modified Studio 200 power amps I am writing regarding my modified Studio 200 power amplifier featured in the January 1990 issue and in particular to the letter to Mailbag from Phil Denniss in the April 1990 issue. I have a number of points to make: (1). The fitting of emitter resistors to Q2 and Q3 was to give some local negative feedback and lower the open loop gain, as I have noticed audible benefits by doing this. I have never been happy with op amp sound where a huge amount of open loop gain is provided and then a vast amount of negative feedback is used to tame the beast. (2). Further audible improvement was noted when Q4 and Q5 were fitted with individual emitter resistors in lieu of a common 1000 resistor. (3). As noted in my clarifying letter to Mailbag (February 1990 issue), Q6 and Q14 are thermally coupled for the very reason Phil Denniss mentioned; ie, VBE tracking (matching) of Q6 and Q14. (4). The main reason for Q15 is to slightly reduce the voltage drop across LEDl as the hFE of Q4 and Q5 increases during warm-up, thereby keeping the Q2 and Q3 collector voltages within less than 5mV of each other. In fact, in my preamplifier, an op amp is used to increase the servo control of Q15 (in conjunction with a preset in the base of Q15) to keep the differential pair collector voltage difference to an absolute minimum. Finally, in anticipation of being labelled as a "golden eared nut", I put my money where my mouth is (figuratively) and demonstrated my continued on page 97 JUNE 1990 3 by Bryan Maher • Large offshore oil-drilling platforms are huge engineering projects, both in their construction and operation. They are electrically self-contained with their own power generation, computer control and robot inspection systems. Large off-shore oil-drilling platforms have become a permanent part of the world scene. These are incredible structures, self-contained and equipped with their own electricity supply, oil drilling equipment, primary refining plant, pumps and compressors. They can drill oil wells through the ocean floor to depths of 6000 metres and more and they they can drill up to 30 oil wells from one position. The oil and gas they obtain is either pumped directly to land refineries or to tanker ships moored alongside. But would you like to work on an oil rig far out in the ocean, perhaps 100km from land? On an oil rig, you live and work on a "platform" supported by long spidery steel legs reaching perhaps 300 metres down to the ocean floor. In the North Sea alone, there are between 180 and 200 such platforms. Many more are in the Gulf of Mexico and off the Pacific coasts of Le~ e large Statsjord-A oil drilling pla m is located in the North Sea. The m ht-time illumination is heightened by the excess gas being burnt on the flare stack. Venezuela, the United States and Alaska. They also sprout in waters off equatorial West Africa and Australia's North West Shelf. The largest oil rigs proliferate in the Persian Gulf. The structures Most platforms are built lying on their side on a land-based slipway and launched like a ship. After being towed to the offshore worksite, watertight sections in the legs are filled with water or concrete to sink the legs to the ocean floor, leaving the whole structure in a vertical attitude. When the steel structure is erected and anchored to the ocean floor, the superstructure is completed. On a typical platform, the lowest deck surmounting the leg structure is up to 20 metres above the ocean surface. Usually, the oil treatment machinery and pumps, being the heaviest, are mounted on the lowest decks. Above this, the "module deck" carries boilers, the power station, workshops, well-heads, gas compressors and gas processing plant. The highest decks carry a number of cranes, the helicopter landing pad and hanger, the gas flare stack, control tower, the 70-metre high oil-drilling derrick and other associated equipment. In between are many decks of air-conditioned control rooms, and sleeping, eating and recreation areas for perhaps 100 workers. This living accommodation can be as high as eight or 10 decks - as big as a large city block of flats. Power station A power station is essential to supply the pumping and electrical load, motors, lighting, airconditioning, water purification, computers and other machinery. Usually four or five alternators rated at 3-5 megawatts each form the primary power station. The electrical load in many cases is from 10-15 megawatts, so that often three alternators are running and one or two sets are on standby. Electrical and mechanical engineers normally prefer to install a number of smaller machines rather than a few larger units. Thus if a serious breakdown occurs, a complete engine or alternator can be airlifted by helicopter to land-based workshops. This is economically reasonable as there is a limit to what can be repaired on the oil platform. A variety of engines will be found driving the alternators. Some early large North Sea and Persian Gulf installations used oil-fired steam boilers and steam turbines. North Sea steam driven plants ran at 3000rpm, driving 2-pole 50Hz alternators, while those under American influence in the Persian Gulf used 3600rpm steam turbines and 2-pole JUNE 1990 5 60Hz alternators. Smaller plants commonly used diesel engines. In later years, the problems of supplying fresh water to oil rigs caused a shift to large diesel engines or gas turbines. Gas turbines would seem a natural for oil-platform power generation as they will run on just about any fuel. However, the efficiency of a gas turbine is very dependent on the ambient temperature; the higher the ambient temperature, the less efficient the turbine. This is such a problem that tropical and Middle East installations now favour large modern diesel engines, while plants in the North Sea tend towards gas turbine drives. Deviation drilling Up to 30 wells are drilled by each platform to maximise access to the oil deposit far below. Wells are drilled at slight angles from the vertical to spread the field. Close computer control of drill bit direction is needed during this deviation drilling to avoid unwanted bends and collisions with existing well pipes. Having drilled a number of wells, oil and gas production is begun. The purpose of the production mach- 6 Computer control is essential for the safe operation of modern oil rigs inery is to separate the wanted oil and gas from the residue. The unwanted water (10%), sand, gravel and other contaminants which always flow up from deep wells must be removed. This process is quite involved and uses heavy, bulky plant. The production technique can be divided into six stages: (1). The oil mixture from all well heads on a platform is combined into two manifolds. Here the pressure is usually between 20 and 35 megapascals (ie, around 3000 to 5000 psi]. (2). The pressure of the stream is reduced by chokes to 10 megapascals and the oil, water and gas are then separated out. Up to three separator stages may be used in series, using large tanks fitted with ViJ,:. I. Upper dffk of a prod11ctio11 platfimn. Fig. 2. Module deck. 1 Living accommodat ion 2 Helideck 3 Heli cop ter hanga r 4 Co ntro l tower 9 Gas injec ti on module 10 Gas compress ion module 11 Well head module 12 Corridor 13 Manifold module 14 Gas treatment SILICON CHIP 5 6 7 8 Cranes Dril lin g derrick Flare stack Drill in g equipment area 15 16 17 16 19 vanes and gas traps. A typical tank is 15 metres long, 3.5 metres in diameter and weighs 150 tonnes (stage 1 tank) when containing 70 kilolitres of oil mix. The mixture takes one minute to pass through each stage. The pressure decreases as the mixture goes through stages 1, 2 and 3, emerging at atmospheric pressure, with water content down to 2% or so. (3). The final water removal stage uses a coalescer, a giant vessel 20 metres long and 4 metres in diameter. The oil mixture rests here for 5 hours while the water separates out (ie, the water sinks to the bottom). The resulting oil now has a water content below 0.1 %. (4). The crude oil passes through the metering stage to the delivery pumps. (5). The delivery pumps are usually rated at 3 to 5 megawatts each and in some North Sea platforms are directly driven by gas turbines. A variation on this method uses double-ended shaft gas turbines driving both an oil delivery pump and a power station alternator. Some recent Norwegian and Swedish oil rigs use 5MW synchronous 11kV 50Hz motors to Main generator Gas treatment Generator module Boiler room Maintenance shop and chemical injection module 20 Emergency generator module 21 Maintenance shop and electrical cont rol room drive the delivery pumps. (6). The natural gas separated out of the mixture is very valuable as fuel. This is dried and compressed in large machines driven by 3-5MW 1 lkV motors or 5MW gas turbines. The pressure required depends on the length of the pipeline to the point of use on land. Long distance land pipelines have 1-5MW relay pumping stations along the way. Some installations highly compress the gas for tanker transport overseas. Computer control Computer control is essential for the safe operation of modern oil rigs. For example, the Danish company ASEA Per Kure has installed computer controlled safety and control equipment on oil drilling rigs in cooperation with the oil companies Maersk of Norway, Mobil of USA and others. Such systems are absolutely vital on all oil platforms, when one considers the volatile nature of the oil and gas, the explosive environment and the very high oil and gas pressures involved. Anyone who doubts the need for stringent control could perhaps recall one rig in the Mexican Gulf Gas compres• ~ - - s,onand dehydration H,O Oil treatment Export pipeline This flow diagram shows the various separation and production processes on an offshore oil rig. All operations are computer controlled. Reservoir which blew its manifold asunder and caught fire. The whole 5000 tonne oil platform literally melted and burned to the waterline with great cost in human life. Sa£ety shut down ASEA Per Kure equipment will safely shut down the whole plant if the oil or gas pressures or temperatures exceed safe limits at any point in the process. Later computer controlled installations, as in the DAN-F platform operated by Maersk Oil and the Gullfaks-A platform in the North Sea, are complete process control systems. Naturally all electric motors, switchgear and control equipment near the oil or gas environment must be housed in explosion-proof casings. This imposes severe design restrictions, particularly where computers, keyboards and control rooms are involved. One solution is to locate some of the electrical and control equipment in sealed airconditioned rooms operating at a slightly positive air pressure. Any gas leak cannot then invade this safe space, so equipment inside does not require explosion proof housings. Pressure relief systems Should the pressure or temperature anywhere in the process exceed safe values, what can be done? Also where does all the water extracted from the crude oil Right: oil-rig process control equipment for Gullfaks A undergoing tests at Asea Per Kure's factory in Oslo. Fig. 3. Lower dee/.:. 22 Ventilation fans 23 Gas condensate treatment 24 Gas treatment 25 Drill pipe area 26 0,1 separators 27 Oil and oily water treatment 28 Ballast water treatment 29 Electrical control room 30 Area above marine riser 31 Pump and auxiliary equipment module 32 Area above equipment shaft 33 Ventilation fan for equipment shaft 34 Heating and ventilation fans 35 Air compressor equipment 36 Main control room ◄ Left: the enormous size of offshore oil rigs can be gauged by the fact that the living accomodation is often eight floors in height. The complete platform is as large as a 5000-10,000 tonne ocean going ship. ]UNE 1990 7 This strange craft is the multi-purpose support vessel Regalia, built by Gotaverken Arendal to provide support for offshore work. The vessel is semisubmersible, has computer control systems and is self-propelled. Note the helicopter landing pad, living area, cranes and large work area. pean waters are politically peaceful, the Persian Gulf is not so lucky. A good friend of the author's, an electrical engineer on a Gulf oil drilling platform between Bahrain and Abadan, tells of constantly living in a war zone. Often under air attack, on one occasion his oil rig became the target for an Exocet missile, which exploded at the oil platform legs, on the waterline. One very large steel leg was blown asunder. But our friend, along with the whole crew, survived unscathed, as the platform continued standing erect. While this is a rather extreme example, it emphasises the need to constantly scrutinise all underwater steelwork. Whether in the North Sea, with its constant gales and storms, or the war-torn Persian Gulf, the original strength of welds in particular can be eroded by fatigue cracks. Such defects, unless repaired by underwater electric welding, can initiate failure of the whole platform under any severe stress, whether caused by man or the sea. (Fatigue in steel is caused by the vibrations of running machinery plus the buffeting strains caused by oceans in turmoil}. Underwater inspection go? You cannot just dump it in the ocean as it still contains some oil and various other contaminants. The computer control system takes care of these problems. Under excess pressure conditions, gas which cannot be pumped ashore or used by the platform boilers or power station may be pumped down another drill pipe. It is thereby returned to the oil deposit far below, the source of the material in the first place. As well as relieving any dangerous pressures on the platform, this practise also helps maintain the flow of oil from the well. Computer control of the gas return pumps regulates the pressure to a value above the oil well pressure. Water removed from the oil is similarly pumped back down the well to the oil deposit. and Saudi Arabia, lies in a war zone bordered by eight independent countries. Beneath lies 60% of the world's proven reserves of crude oil and natural gas. Here, offshore oil drilling platforms, owned and operated by American, Japanese and European companies, supply much of the industrialised nations' fuel needs. The enormous size of these oil platforms and the scope of their electrical engineering is hard to visualise. Their huge oil pumps shift the crude oil to land via underwater pipes big enough for a man to stand erect and walk through. Each pipeline carries one million barrels of crude oil daily right across Arabia to the Mediterranean seaports at Telkalakh and Baniyas. A number of relay pumping stations line the route. Persian Gulf oil War damage The Persian Gulf, between Iran 8 SILICON CHIP Whereas Australian and Euro- Until recent times, deepsea divers continually risked their lives inspecting all submerged steelwork. Particular attention is necessary in the vital joint areas the "K" structure nodes. On oil-rig platforms, all structural work between the ocean surface and the limit of strong sunlight penetration (about 50 metres depth} quickly becomes encrusted with barnacles and various marine growth. This must be removed to enable inspection for hidden fatigue cracks, a cleaning job divers find difficult in the extreme. Momentum reaction while underwater, handling high pressure water jets and hydraulically driven brushes, makes for tedious and arduous work. Furthermore, diving 300 metres to reach the bottom of some structures is a slow, dangerous occupation for which few are suited. Yet inspection for fatigue cracks is absolutely vital. Robots to the rescue Why not design a machine to perform the task? Robots are a natural for performing difficult repetitive tasks, particularly in environments perilous to humans. In June 1986, the Swedish Company ASEA Oil & Gas announced the development of a deep sea computer controlled robot to perform this work. It is called ROCIS which stands for "Remotely Operated Crack Inspection System" . The method of crack detection is based on eddy current techniques. Eddy current testing With a clean piece of flawless homogenous steel on the test bench, eddy current tests are straightforward. An AC magnetic field applied to the steel induces eddy currents therein and these eddy currents set up their own secondary magnetic fields. A field strength sensor will then find a regular magnetic field strength over the surface. Now if we substitute a steel sample containing a surface defect, the results are different. The defect or crack interrupts the surface eddy currents. This produces strong local magnetic poles on either side of the crack. Measurements close to the surface readily detect this abrupt change in field strength, indicating the crack. It's all so easy in the laboratory but it's not so simple at the worksite! Marine growth covering the steel is not a bit constant in thickness. Therefore, a simple magnetic field sensor gives different readings when moving over the steel, riding up and down on the This artist's impression shows the ROCIS inspecting a welded steel joint deep below the ocean (transparent view). Note the claw arms with gripping wheels which drive the robot around the steel beam. The front arm carries the small eddy current crack detector. deposits of marine growth. Furthermore, there is no guarantee of homogeneity in the steel composition in the various members of a structural joint. The welding rods originally used may also be of different alloy content. Although 14 companies worldwide were invited to participate in the development of undersea crack detector, most believed the task too difficult. However, a few did collaborate with ASEA Oil & Gas to produce a highly effective device. As the graph shows, the sensor can detect surface cracks in steel covered by up to 15mm of marine growth. Therefore, only rough cleaning is needed prior to testing. Crack detection responses The detection system cannot avoid responding to normal welds, as any join must create a magnetic discontinuity. These readings must be recognised as welds, not cracks. Oily water Three separator stages are involved in removing the water & gas content from the crude oil. This process occupies much of the space on an offshore oil rig. This diagram shows some of the internal details of the separator vessels. The vessel is typically 15 metres long and 3.5 metres across and can hold 70,000 litres of oil. JUNE 1990 9 Thus, the robot is safe even in the strongest ocean storms. Test display In this drawing, the ROCIS is shown inspecting a K node in the underwater steelwork below the platform. The human diver is shown for size comparison. Normally, the robot works without human intervention but humam divers still have to weld any cracks that are detected. Tests have shown that when the crack detector moves above the steel, maintaining about 10mm separation, the system yields the best distinction ratio in crack/weld responses. In practise, this means that marine growth up to a thickness of 10mm can be tolerated. Results achieved in underwater tests show that the smallest crack detectable in steel members or welds is 15mm long and 2mm deep if the sensor is within 5mm of the steel, or 30mm long and 2mm deep when the sensor is 15mm above the steel. These measurements show a signal/noise ratio of about + lOdB. The above performance is independent of the intercept angle, so the sensor can respond correctly when poked into the corner of a joint. The robot finally developed has a relatively small wrap-around body 10 SILICON CHIP one metre wide, 800mm long and 400mm high. From the body extend claw-like side arms and a telescopic front arm which carries the crack sensor. All joints, the claws and the telescopic arm are electrohydraulically driven, each with its own actuator. Electric motors and hydraulics are located within the main body, while all electronic circuitry is housed in sealed compartments, waterproof to 300 metres. A remotely operated vehicle lifts the robot from its storage area and places it on the structural member to be tested. This action is supervised remotely by the control operator. From this point on, the robot operation is automatic until one joint is completely inspected. The hydraulics wrap the clawarms tightly around any circular steel member measuring between 500mm and 1.2 metres in diameter. Output signals from the robot, the crack sensor and the video cameras are processed in a computer and displayed on two screens. One VDU shows computerreconstructed images of the weld being inspected. This readout highlights any cracks and pinpoints their location even though they may be covered by marine growth. The second display is a 3-dimensional real-time video picture of the robot's position and the area being treated. When first used, the robot was remotely controlled by an operator. Later, the operation was made completely automatic. An adaptive automatic control system was developed in cooperation with Trallfa Robotics A/S of Byrne, Norway. This digital system controls all operations. Once placed on the girder by the Remote Operated Vehicle, the robot finds its own way to the work site and the weld to be inspected. It then proceeds with the complete crack test. In operation, the robot rotates around the steel member 180° clockwise, checking for cracks. Then, to avoid entangling the umbilical cable, the robot returns anticlockwise to its starting position and proceeds around the girder to test the other side. Initially, the rough cleaning required before testing was performed by divers, until scrubbing equipment was later carried by the robot. There is only one problem still to be addressed: once cracks are found, how are they repaired? The answer is that the poor old humans still have to go down and do the job. When that task is finally automated, even larger oil drilling platforms will be able to stand in even greater ocean depths. Acknowledgement The author thanks ASEA Journal and Bill Fitzgerald and Don Smith of ABB for data, photos and permission to publish. ~ ADCOLA RS30 Soldering Iron ADCOLA RS50 Soldering Iron ADCOLA RS&O Soldering Iron ADCOLA DR30 DUOTEMP • 12 watt mains powered • Well ba lanced design • Long-life Triclad 3mm tip Cat T-1820 • 16 watts mains powered • reliable heavy duty element • Long-life Triclad 5mm tip Cat T-1825 • 21 watts mains powered • lightweight, super-slim barrel! • anti-seize 6.5mm tip Cat T-1835 • Normal and Push-button Boost temperature settings! • 21 watts on boost • Can be fitted with a variety of specialist tips Cat T-1830 s3995 s42s5 s49s5 s59 2 Tip Replacement Packs 5 Tip Replacement Packs s19s5 •To suit the ADCOLA irons • To suit the ADCOLA irons ins Cat T-1860/-1862/-1864 PORTASOL Butane Soldering Iron • • • • Fits in your pocket! 60 minutes continuous use on high 10 to 60 watts temperature control totally portable Replacement Tips Cat T-1372 Cat T-1369 Cat T-1371 Cat T-1373 Cat T-1368 1.0mm 2.4mm 3.2mm 4.8mm Hot Knife S15 95 each Soldering Iron Stand • Suits most medium sized irons • Stable die-cast base • With sponge holder & sponge • Can be attached to your bench CatT-1303 sgs5 s49 Cat T-1861/-1863/-1865 Desoldering Bulb • The fast way to remove solder! • Sucks the molten solder off your work PORTASOL 'Pocket' Soldering System • • • • • Replacement Tips g:i t~3~i 10-60 watts power Cat T-1379 Butane powered- refills in seconds Cat T-1381 Averages 90 minutes continuous use Cat T-1376 4 tips including knife & blow torch Cat T-1377 Case with clip-on iron stand Cat T-1382 Cat T-1374 jijiiiiiiijjij,_. 69 t~~~ 3.2mm 4.8mm. Hot Knife Blow Torch Hot Blow s15s5each 5 Soldering Aid Set • • • • Fine point & slotted end probe Scraper end & wire brush probe Angled scriber and scraper probe Aluminium heatsink Cat T-2606 :;~~~;:~,: . -D--1-t~:.~=-::~:""'"""~--~~,.....,. - Super VGA Graphics Adaptor _,, • • • • 256k on board expandable to 512k XT or AT compatible Can emulate EGA, CGA, and Hercules cards One of the most inexpensive VGAs around! 8-bit version Cat X-2018 16-bit version Cat X-2019 .. ;:.-;,, ::- - ' nnn~•J :!,.;_,1 "..... .. ,,,.?r~» n .,'!l ,"l-"1.,'Ji ~-- "''' ,.,'!'! '!'!'!'J't "" '.t "!'1 '\'1'! '!,-'f 't ;..,...,'t. "l."l."l'!:'!'J'J ~ , .... , .; .,,,. '!l-"1. '!'J 1 "' RS-232 Breakout Box 80286 AT Motherboard 20MHz 'Neat' AT Motherboard • Fits into any desktop IBM compatible XT • 8.9MHz clock speed • Unbelievably small ! • 8 expansion slots • Socketed for 640k on board (Ok supplied) $ • 12MHz clock speed • Expandable to 1Mb or 4Mb on board (Ok supplied) • Six 16-bit and two 8-bit expansion slots • 80287 co-processor socket • AMI BIOS ROMs included • With 'NEAT' (New Enhanced AT) chip set • Selectable 8, 10, or 20MHz clock speed • On board support for LIMS EMS - version 4.0. • 80287 co-processor socket • Five 16-bit and three 8-bit expansion slots • Expandable to 8Mb using SIP & DIP modules (Ok supplied) Cat X- 1003 $ 149 Cat X-1002 s399 The DSE Solder Statior4 • A professional Soldering Station at a hobbyist price! • Variable temperature control from 200-500°C • Temperature meter for exact control • Includes lightweight iron holder and cleaning Cat T-2000 s135 Cat X-2654 699 RS-232 Loopback Tester • Conducts data verification by returning o·utput data back into your computer • 4 LEDs let you know what's going on by monitor lines 2-3, 4-5, 6-20, and 15-17 11!:b::::= = - Cat X-2651 s199s s4995 Prototype Card • Veroboard expansion card • With interrupt and memory addressing circuits installed • XT/AT compatible I 3 in 1 Modular Tool • It's a Drill, Soldering Iron, and Screwdriver all in one! • Modular components snap onto rechargable ..<at>~~ ~~illi:;;;;!!!!o battery pack • Comes with assorted dri II s, screwdriver _bits, and solder accessori~ • AC charger included ~ sgg712 s299 Mini XT Motherboard Cat X-1001 • A complete in-line tester that makes serial connections a breeze • 25-pin male to female connectors • Jumper pads and wires included • 24 in-line isolating switches • Eight bi-colour LEDs for line testing S249 ~ 11 • Comprehensive manuai $ ~ .",'!l"lt: ~'V,l~U ~-~gx~,r;~~1~ - . _=_:£3E Cat X-2034 I,lit • ,_,.,__--')-;· ....:,,,..... :·! !· 149 U 11111111111111ilL !11!11 ii I I Computer Service Kit • All you need to rip your computer to pieces is right here! • IC inserter & IC extractor • 3-claw holder & needlenose pliers Phillips & flat-head screwdrivers • Reversible torque screwdriver • Nut drivers & tweezers • Handy zippered case ~I'---------- • Cat T-4839 s4995 ... "' ,.: · -_,: ,c.". ~ _.;_ ...,, ..'·,,.... - Ii! iL, COMPUTER BYTES! 0 0 0 Bit Blitzer 124E Modem • Low power reliable Modem • Meets CCITT V.21, V.22, V.22bis & Bell 103/212A standards • 2400, 1200, and 300 baud rates are software selectable • Hayes AT compatible • Sturdy metal case with built-in speaker Cat X-3309 AT Style Keyboard • Put an end to all that fumbling with combined numeric and cursor keys! • 101 keys including 12 function keys • Feels great too- with ALPS key switches for accurate, positive touch S129 ' ,.,., .. . ' - - ~ -=· -· -- Cat X-2690 Modem Cable ... Cat X-2691 Printer Cable • Connects RS-232 devices to your Apple or Mac • DB-25 male to 8-pin male mini Cat X-2692 Din Printer Cable Quality DSE Disks • Connects lmageWriter and LaserWriter printers to your Apple or Mac • 8-pin male mini DIN plugs both ends Twin Port Joystick Card Cat X-2693 Adaptor Cable • IBM compatible games card • A breeze to fit and use • Now you don't have to take turns. Play against your opponent in real time! Printer Stands s19e5 each Cat X-2040 1495 Cat X-3814 Moulded plastic stand with paper store. S Adjustable width for any width printer. . . ters Cat X-3812 Wire stand with paper store for wI'd e carnage prtn ~~ • Our expanded range includes High Density versions of both 5¼" and 3½" disks in packs of 10. • Now in our handy new flip top containers Cat X-3501 5¼" DS/DD $19.95 Cat X-3509 5¼" DS/HD $29.95 Cat X-3517 3½" DS/DD $29.95 Cat X-3511 3½" DS/HD $49.95 • Connects RS-232 modems or printers to your Apple or Mac • DB-25 male to 8-pin male mini • DE9 female to 8-pin male mini DIN • Allows you to use standard cables with your Apple or Mac ~ -· ·- ::- s399 Apple 11 And Macintosh Cables . Cat X-3821 S2995 Cat X-3811 Standard size wire stand with paper store s249s DS XPRESS PHONE & MAILORDER SERVICE Outside Sydney (FREE Call) 008 22 6610 Sydney And Enquiries - 888 2105 FAX: (02) 805 1986 or write to OS XPRESS, PO BOX 321 N/RYDE NSW 2113 All Major Credit Cards Accepted. 0/Nite Courier Available. 24 HOUR DESPATCH OF ALL ORDERS s39e5 Anti-Static Wrist Strap • A must for when installing expansion card and memory chips! • Coiled ground lead and adjustable fastening • High value series resistor for added safety. Cat X-2042 s19e5 Su~erset-590 SX 80386 sx Technology • • • • • • • VGA Monochrome Monitor Includes MS.DOS 4.01 1.2Mb High density 5¼" Floppy disk 40Mb 28ms Hard Drive 12 months warranty 2 serial & 1 parallel ports 1Mb RAM expandable up to 5Mb onboard. Supports Shadow RAM . • 4 free 16 bit expansion slots • AT style keyboard • 80387SX Maths Co-processor socket • Latest surface-mount technology throughout UNBEATABLE AT s2995 Major Authorised Stockists N.S.W.: AAM1DALE : New England Electronics 711655 BALLINA : Ball ina Electronics 867022 BOWRAL: F.R.H. Electr ical 611861 BROKEN Hill : Hobbies & Electronics 884098 COOTAMUNORA: Cootamundra Music & Ute 422561 COFFS HARBOUR: CoNs Harbour Electronics 525684 OENIUOUIN : Deni Electronics 813672 OUBBO : Chris 's Hi Fi 82871 1FORSTER : 5 5 3 o;i~d 9 1 ~;~~; vd~f~;,f~~i?;~co ni~!s~:s~~E~~iiil:L/~~:e~1~~~~~donei~it~~~i821 iii\ri~~~:!~~::ig;~ifr s~~BJJ ~~~~~~iM~~~i~~;i~,~~:~~fc~lios~ ~HuGJG1E~~~1w~~t~jftf~l~t1~~:'t~~~T:c~~;~,~~e~~~v~~ce ~2J~jl l,\ NELSON BAY : Nelson Bay Elect & Hobbies 813685 NOWRA : Nowra Electronics 210722 ORANGE : Central West Electronics 5 66 8 45 ife~;~nrc~A:~~tr~G't iA~&!~ ~~~ s lt~c~~oi~c~~tsRJ: :y~~:n8lar~i~c~~rE~~\~it l6 1 \AluENE~: B~:~J Donges Electronics 821279 VIC: BAIANSDfLE: LH & LM Crawford 525677 COLAC: Colac Electronics 312847 MlLOURA : Pullman Auto Pro 232882 MOAWELL: Morwell Electronics 346133 SHEPPARTON : Andrew Guyatt Electronics 219497 SWAN 0 ~:ii~~i~eJ;;c;6~~:~Ai~=~~~~ E,~?Jii:c;r~~;;;~21::5R~:C~oLriA~ i~rg~~~s Dysart Videotronixs 582107 JNGHAM : Masons Electronics 763188 MACKAY : Stevens Electronics 511 723 MARY BOROUGH : Keller Electronics 214559NAMBOUR: Nambour El ectron icsShop411604 Pt ALBA : Keller Electronic s 283749 TAS: BURNIE : Electronic City 314760 DEVONPORT: A.I.Electronics 248322 SA: MT GAMBIEA: Hutchesson ·s Com munication Centre 250400 POAT LINCOLN: Basshams TV & Comp World 822788 WHYALLA : Eyr.e Electronics 454764 WA: ALBANY: Micro Electronics 41 'l077 BUNBUAY: Micro Electronics 216222 GEAALOTON : Batavia lighting & Electr ical 211966 KAAAATHA : Daves Oscitronic 854836 MANDRAH: Micro Electronics 5812206 POAT HEOLANO: Ivan Tomek the Elect 73253 1 ~t~: ~~: E~i~,~~-~;~, o\2lt~i: nnn .uuu 'J Digital Multimeter A full featured DMM at this price? It could only be from Dick Smith Electronics! • Autoranging & auto polarity • Transistor testing • Audible continuity testing • Data hold . - - - - - - - - - - - - - - - - . • Fast 1/2 second cycling Ranges : • High level overload protection Cat Q-1516 Vdc 0.2, 2, 20, 200, 1000V Vac 2, 20, 200, 750V DC current 20mA, 200mA, 10A U I AC current 20mA, 200mA, 10A A lightweight cradle for the Q-1516 Digital Multimeter that comes with its own Resistance 200, 2k, 20k, 200k, 2M, 20M belt. Use it on the benchtop or clip it to the belt for 'go anywhere' action . Trans. check Hfe cat a-1s22 Continuity buzzer S109 M 11·lmeIer Cra die w·th BeIt . _ - - - - - - - - - ~ ~.. s995 AC Voltage Probe Temperature Here's a probe you should never be Probe Adaptor without! It senses anything above 60 volts right through the insulation . Now you'll never get caught out by dangerous AC voltages again. Now your multimeter can measure temperature too! Simply plug into your meter and set it for DC volts. The probe supplied operates from its own battery and has a range of -50 °C to 260°C. Cat Q-1430 Cat Q-1530 Don 't ti e up you r multimeter just for logic tests! With this logic probe you'll be readi ng logic states the easy way. • Adjustable threshold for TTL or CMOS • Pulse or hold mode • No batteries! Uses power from the circuits you're testing . • Cat Q-1272 s59u Banana Plug Leads Coiled Test Leads 900mm test leads with standard probes and 4mm fully insulated banana plugs. End the hassle of endless leads cluttering up your workbench with these retractable CatQ-1912 Cat Q-1916 s395 3 - State Logic Probe s3595 ~~ s1395 ~ Resistance Light Duty Substitution Jumper Kit Colour coded 10 piece jumper Wheel lead set with small insulated alligator clips. Cat Q-1 900 S650 ~~~~~, LCD Panel Meter 3 Digit Counter This has got to be the handiest counter circuit around! Ideal for integrating with your larger project or as a stand alone device. ~ • 5 to 15Vdc supply ◄~ • LED display • Up to 2MHz counting speed Cat K-3451 s29s5 Cat K-3450 $ 4995 VK Powermate 25 Dual Tracking +/50V Power Supply This power supply can really deliver the goods with variable output from OV to an incredible 100 volts DC! Ideal for TV servicing. • Variable current to 1.7 Amps • LED indicator for ripple exceeding SmV p-p • Short-circuit protected • Pre-punched and screened front panel Cat K-3465 - An accurate Panel Meter with a large liquid crystal display. Use it as a readout device on any • of your new projects. • Power 5V to 15Vdc (1mA<at> SV) • 3 1/2 digit display • 100uV resolution • 1 digit accuracy The ultimate power supply for amateur radio! If you have your sights set on a transmitter in the 100-150 watt class .... this is the kit to drive it. • 25A continuous & 35A peak current • Foldback current limiting & crowbar protection · • Deluxe front panel label • Case H-2481 & tr~nsformers M-2010 not supplied. $249 Cat K-3210 Portable AM Stereo Radio components. Cat K-5200 With this sophisticated unit you can charge your sealed lead-acid batteries with out fear out overcharging or shortening battery life. • Uses Unitrode UC3906 charger IC • Current selectable for batteries up to 1SAH • Switches to trickle LEDs • Suits case H-2812 and transformers M-2000 (not supplied with this kit) • Includes front panel label and components. Cat K-3220 ssg 144-148MHz Amateur Band Converter This converter will allow you to receive the 2m amateur band on your 50-54MHz receiver (K-6005). The modular design ol this circuit allows it to fit comfortably inside the K-6005 receiver, so changing bands will be as easy as flicking the switch . s249 A wide band AM Stereo Radio that's easy ~~-~~~~ to bui Id and needs no fancy tools to •.. 1, complete. The kit includes a case, stereo · · headphones, pre-punched • front panel , panel label and all $ 95 6/12 Volt SLA Battery Charger Cat K-6006 s49s5 FM Radio Intercom For Motor Bikes Break the silence on those long trips! With a voice activated microphone and speakers built-in to your helmet, this system is totally hands free and invisible. When travelling alone, you can even tune in to your favourite FM radio station . Cat K-6020 s79s5 M-~.n _ ADEINUSJ\ VGITAL MULTl·Mi.'ti 3YEAR WARRANTY! The Incredible Fluke 87 Fluke 73 Uncompromised quality at an affordable price. The superb autoranging FLUKE 73 is just the thing to withstand the roug h and tumble of everyday use. • 3.5 digit, 3200 count multimeter • 31 segment bargraph • Autoranging & automatic polarity • High energy overload protection • Every feature on one rotary dial! Cat Q-1602 5 179 You 'll wish that al l your test equipment could perform so well , last so long, and give you so much flexibility! • 4.5 dig it & Analogue Bargraph readout • Auto & manual rang ing • Frequency & true RMS • Capacitance • Minimax average recording • Overload protection • Continuity & diode testing • Touch hold • Back-l it display plus lots more! Cat 0-1610 Fluke 75 With all the features of the FLUKE 73 plus diode and aud ible continuity testing! • 3.5 digit multimeter • 31 segment bargraph • Autoranging & automatic polarity • Audible continuity testing • Diode test • Dirt and moisture resistant case S699 Fluke 77 Cat 0-1604 The feature packed FLUKE 77 is the top of the line 70 series multimeter with advanced features like Touch Hold and superior accuracy (0. 3% for 3.2 to 320V). • Autorangi ng & automatic polarity • 3. 5 digit plus 31 segment bargraph • Touch Hold with 'beep' indicator • Continuity & diode test • Superior accuracy across most ranges • Hand carry holster Cat Q-1606 289 s399 5 Genuine Fluke Accessories Universal Temperature Probe A P-N junction probe that converts any DMM into a thermometer. Range: -50°C to 150°G. Switch selectable for °C or °F. Cat 0-1680 Air Probe For air and other gases. Protected probe with perforated stainless steel baffle. Range: -196°C to 816°C. Cat 0-1686 $119 Immersion Probe High Voltage Probe AC Clamp Meter AC/DC Clamp Meter For liqu ids and gels. Fully protected by lnconel sheath. Range : -196°C to 927°C. Extends your measurement capabilities up to 40K volts using a division ratio of 1000 to 1. Hall-effect clamp metre accessory with its own battery. Measures currents from 1 to 400A and fits conductors up to 30mm dia. Battery powered Halleffect meter for conductors up to 30mm dia. Measures currents from 5 to 400A at frequenc ies up to 400Hz. Cat 0-1690 $159 Cat 0-1670 ~~- $279 " Cat 0-1672 s299 '199~ ~ .! Deluxe Test Lead Kit Standard shrouded banana plug leads with interchangeable tips in a soft carry pouch . Comes with all igator clips, spade lugs, standard pointed tips, and one retractable hook tip. 95 Cat 0-1658 $ 59 Industrial Test Lead Set 1.6m silicon insulated test leads with interchangeable stainless steel test probes and safety alligator clips. Cat 0-1652 s7995 Dick Smith Electronics Stores • NSW • Albury 21 8399 • Ban kstown Square 707 4888 • Belconncn (062) 53 1785 • Black!own 67 1 7722 • BroOkvale 905 0441 • Bondi 387 1444 • Campbelltown 27 21 99 • Chatswood Chase 4 11 1955 • Chullora 642 8922 • Gore Hi!l 439 53 11 • Gostord 250235• Hornsby 477 6633 • Hurstville 580 8622 • Kotara 56 2092 • Liverpool 600 9888 • Maitland 33 7866 • Miranda 525 2722 • Newcastle 61 1896 • North Ryde 878 3855• Parramatta 689 2188 • Penrith 32 3400 • Ra ilway Square 211 3777 • Sydney City 267 91 11 • Tamworth 66 1711 • Wollongong 28 3800 • ACT• Fyshwtck 80 4944 •VIC • Balla rat 31 5433 • Belmont 43 8522 • Bendigo 43 0388 • Box Hill 890 0699 • Coburg 383 4455 • Oandenong 794 9377 • East Bnghton 592 2366 • Essendon 379 7444 • Footscray 689 2055 • Frankstoo 783 9144 • Gcelong 232 711 • Melbourne City 399 Elizabeth St 326 6088 and 246 Bourke St 639 0396 • Richmond 428 1614 • Ringwood 879 5338 • Spnngvale 547 0522 • QLD • Bnsbane City 229 9377 •Bura nda 39 1 6233 • Cairns 311 515 • Cherms,de 359 6255 • Redbank 288 5599 • Rockhampton 27 9644 • Southport 32 9033 • Toowoomba 38 4300 • Townsville 72 5722 • Underwood 341 0844 • SA • Ad elai de City 2234 122 • Beverley 347 1900• Elizabeth 255 6099 • Enl1e ld 2606088 • St. Marys 277 8977 • WA• Ca nn ington 451 8666 • Fremantle 335 9733 • Per1 r1 City 481 3261 • Mid land 250 1460 • Northbridge 328 6944 • TA S • Hobart 31 0800 • NT• Stuart Park 81 1977 Soft Case Protective case for FLUKE meters. With water res istant zipper and ~ockets for leads. Even fits FLUKE olster! $ Cat Q-1664 4995 Holster With lead and probe pouch plus tilt stand and belt hook. Suits any of the FLUKE 70 series DMMs. Cat 0-1663 s3295 . Fitting a fax card to your computer Fax cards for the personal computer are not new - in fact, they've been around for some time. The theory is fantastic although practical application can sometimes leave a bit to be desired. Here we take a look at the pros and cons of fax cards. By JENNIFER BONNITCHA Our sample fax card was Viemar System's Fax89 which provides all the capabilities of a standalone facsimile machine, and then some, on your trusty PC. You can send and receive facsimile messages over your telephone line, store images for retransmission to other destina18 SILICON CHIP tions, print as many copies as required, queue documents while transmitting or receiving, and schedule documents for predetermined transmission times. When you consider that fax rolls cost around $14 per 100-metre roll, the option to print only those faxes you want, and then on plain paper, is quite attractive. Think of the amount of money you could save on junk faxes alone! The Fax89 requires an IBM PC, XT, AT or compatible with a hard disc, at least 512K of RAM and DOS 3.0 or later. Useful is an EGA or better graphics card, although the documentation suggests that MGA, CGA, EGA, VGA and Hercules graphics cards are all supported. Printing the fax is no problem either provided you have a Toshiba, HP Laser Jet, Epson FX or LQ series, IBM Proprinter, or any printer compatible with one of the preceding. Included with the half-length fax card are three 5.25-inch discs, a telephone cord and a rather comprehensive manual. However, I get the feeling that the manual has been recently upgraded since, from Chapter 6 onwards, the print quality improves dramatically and the sometimes erratic indexing also becomes more accurate. According to a label on the fax card, it also has full Telecom authorisation. Fax89 is CCITT (International Telegraph and Telephone Consultative Committee) Group III compatible. CCITT establishes and recommends communications standards and Group III is one such standard. Over 99% of the world's installed facsimile machines are Group III machines, so you should have no trouble communicating with the world at large. One of the problems associated with fax cards is the requirement of a COM port. While this may seem of little significance, consider the plight of someone with a serial mouse, modem and printer. Although a bus mouse and parallel printer solve the problem, what happens when you already have serial devices? Memory demands from the resident fax software can also create problems for an already overtaxed PC. The card usually operates in the background so your computer is free for other tasks while transmitting or receiving faxes. It usually operates at 9600 bps, however it can automatically decrease the speed of operation to match both the remote facsimile machine and the quality of the line. Known as automatic fallback, this means Fax89 can drop to 7200, 4800 or 2400 bps, depending on the prevailing conditions. Fax89 also has the ability to operate in the foreground but most users will probably choose the background mode. Foreground mode freezes other applications and the screen display but on the other hand, some programs may not operate when Fax89 is running in background mode. Timing is of the essence since programs which hold the CPU for too long can corrupt facsimile documents or the computer may come to a screaming halt (CRASH!}. If this should occur, you can simply disable background operation. However, this tends to defeat The half-length Fax89 card plugs into an expansion slot in your PC-compatible machine. It normally operates in the background which means that you can go about other tasks while transmitting or receiving faxes. f?AXK9 F Ai:'.SI.M tt,E 1.JS.H R '"S: GlHl)B Three 5.25-inch software discs, a telephone cable and a comprehensive manual are supplied with the Fax89 card. the purpose of having a fax card. Time saving is important and, let's face it, none of us are getting any younger. With Fax89, you can send faxes directly from your word processing software provided a memory-resident utility is loaded first. Fax89 also lets you place documents in a queue for transmission and you can schedule transmissions when telephone rates are at their cheapest. As with most Fax89 operations, you can do this either from the Menu System or from the DOS command line. Once you a re familiar with the appropriate commands, you will probably bypass the Menu System in most cases. However, it is nice to see a menu which is uncluttered, easy to use and with an acceptable level of help. Included on the Utilities discs are sample Header and Signature files which you may like to add to the beginning of your fax document. If you own a Chinon or compatible scanner, you can use the Scan JUNE 1990 19 This on-screen menu lets you convert other files (eg, word processor or TIFF) to FAX format for transmission. This photo shows the setup menu for sending & receiving faxes. The menu-driven system is easy to operate. The incoming register shows the date & time of reception. The received fax can be viewed on-screen or printed out. Menu to scan and convert an original document, thus giving you as much flexibility as using a "real" fax. You can also use almost any pre-scanned image provided it is in Tag Image File Format (TIFF), PC Paintbrush Plus [PCX) or DR Halo (CUT) format. Installation Installing the Fax89 was quite simple and I used an NEC PowerMate 1 Plus to test the card. Just remove the PC cover, locate an empty slot, plug it in, attach the phone cord to the PC and phone socket and away you go. Remember though, you need to use either COMl or COM2. Fax89 is preconfigured to operate on COM2 and once the software was installed, off we went, ready to fax merrily to all and sundry. Installation creates three directories called FAX, FAX IN and FAX OUT and copies the appropriate 20 SILICON CHIP files from the Program and Utilities discs. Obviously FAX IN holds your incoming faxes and activity log, while FAX OUT holds the outgoing faxes and activity log. Immediately following the Software Installation section in the manual is a section called Quick Start, where you get the chance to send a sample fax. I had no problems in either following the instructions or sending the fax. In fact, a complete novice subsequently installed the card and software and sent a test fax just to confirm my suspicions. Faxing Having sent the initial fax, it was time to get down to the real nuts and bolts of the system. The F AXSYS driver remains in memory so Fax89 can answer all calls and receive fax documents without interrupting your current application. You can even use voice and fax at the same time, provided the other person is speaking on a line where they can switch from voice to fax transmission. The FAX program lets you operate all the functions of the Fax89 by using an easy to follow menu-driven system. Creating and sending faxes is fairly straightforward. You write the text in any word processor and then save it in ASCII format to the FAX OUT directory [you can also include the extended ASCII graphics characters). Documents to be sent using Fax89 must be in FAX format. Once again you can use either the Menu System or DOS command line utilities to convert the file. If you use the Menu System, you can check the FAX file before it is sent using the View File option. Using the Menu System also allows you to see how the header and signature file [if used) appear with your fax document. When sending a fax, the computer beeps twice at the start of the transmission and then once on completion. A font editor is provided so you can choose between four fonts in your fax documents - Standard, Bold, Italics and Compressed. You can also create you own fonts using the supplied MAKEFONT utility. You then simply substitute the name of the font file you created for the name of another font file in the Menu System Configuration Window. By using the appropriate escape codes, you can make parts of your document print in any of the available fonts. CONTi\ill FUNCTIONS EXPLANATION i ; ~ ./ / , 1 Swh:ri {1/ Swhnfi {Oi ;,l; ,_,:t,-i_ ui1 ~: ; ~~ ~ ~--!"'":, . ~·....: c... ,...yv .,)' ,,. "" '" .·,~.'~~--u 'S.11111 the !Witch to ,;APPLE" or "IBM" for your oomputer (opt!nn,i! ____., ,s_'~ EUCTRICAl TRIM AllJUSiMENTS Maks 1ur1 that your lovttlck Ii under th, SeLF·CENTEFUNG po;ltlon lr, A!'Pi.E PC. Sy Input; Receiving faxes 10 PDL(OI POLO I Although there is no on-screen advice that a fax has been received, the computer beeps three times when the fax transmission starts and once on completion. During transmission, you can keep on working on your spreadsheet, word processor or accounting program, etc, and scan the incoming documents at your leisure. To do this, you just select Receive from the Main Menu, then Select File, and then select View from the Receive Menu. You can then view the selected document in either of two magnifications. Printing the fax is just a matter of selecting Print from the Print Menu. I printed out a number of faxes on a dot matrix printer and the quality is at least equivalent and, in some cases superior, to a normal fax machine. Evidently, the printer is used in dot-addressable mode so that virtually no details are lost, compared to conventional fax printouts. This will depend to a large extent on the send quality of the source fax machine and the amount of noise on your telephone line. If for some reason you need to interrupt the print procedure, you can cancel quite easily by pressing S. Printing ceases when the print buffer is exhausted. A particular advantage is the not insignificant fact that printer paper does not deteriorate (unless the dog eats it!) unlike fax paper. Therefore, you need never make photocopies (at an additonal cost of 20 GO TO 10 :iO l'iUN I Rot!tg tht thumb\=1rliiii {Al 1.mtii tht numbisr II -128 v.niii; ,Me JoyiiiQI( in oenw ,mition, Printing the received fax is just a matter of selecting Print from the Print Menu. The quality of the printout is at least equivalent (and often superior) to that from a conventional fax machine. around 12 cents per page) of those faxes you wish to keep for posterity. The Edit option of the View Menu lets you cut out horizontal portions of a fax document - this is handy when you want to combine a number of documents. Sadly, editing a FAX document only lets you cut off part of the document and place it in a new file. If you want to alter the contents of the document, you need to return to your word processor. Alternatively, you can convert the FAX document to, for example, PC Paintbrush Plus format, edit it, and then convert it back to FAX format - phew! Documentation As mentioned earlier, the documentation has a few niggling problems with the index, although I am reliably informed a new version of the manual is available. There are lots of words and some screen shots - perhaps a few more would enhance the readability and understandability, especially for novice users. The use of each utility is first explained in summary and then in further detail, while the Appendix section contains helpful sections like Installation Troubleshooting, Background Operation Considerations, a Glossary of Terms used throughout the manual and the Fax89 specifications. The Index is adequate without being outstanding - again for the novice user, a little more cross-referencing would help. Windup - at last! In summary then, fax cards and specifically the Fax89 provide a low-cost entry to the world of faxing. If you use a fax infrequently, you don't need a dedicated fax line, nor a standalone fax machine. The ability · to print only those faxes which are of direct importance to your business/life is also very important - the amount of money wasted on "junk" faxes is quite astounding when the cost of fax paper is taken into account. With Fax89, you can queue your documents for sending at a date and time most convenient (and at continued on page 55 JUNE 1990 21 VINTAGE RADIO By JOHN HILL How to recognise AC/DC sets There are several major differences between AC/DC sets and sets designed to run on AC power only. AC/DC sets don't have a mains transformer but include a special device known as a barretter tube. During the early days of electrification, not all household power supplies were AC. Many small country towns had their own generating station and in most instances, the supply was direct current. While this mattered little regarding lighting or heating, there were considerable problems as far as radios and any other device that used a power transformer were concerned. If a standard AC-operated radio is plugged into a DC supply, it will not work. What's more, if the set is left plugged in for even a few minutes, considerable damage can be done to the power transformer. In a very short space of time the transformer will overheat and smoke will billow forth. I have this on good report from my father-in-law who did just that. He tried to use his radio (a 1940 model 5-valve Kriesler) on a DC supply and it belched smoke almost immediately. Fortunately, the set was turned off before any serious damage was incurred and the old Kriesler still works today. This happened at Charlton, Victoria in the early 1950s - not that long ago. AC/DC sets usually have two or more valves with higher voltage heaters than the more common 6.3V types. Shown is a 25Z6 rectifier and a type 43, both of which have a 25 volt heater. 22 SILICON CHIP The reason for the problem is simple: DC cannot be transformed to other voltages. It just surges through the primary winding in one direction, rapidly heating the winding in the process. There is no constantly reversing primary current with its accompanying back EMF to protect the primary winding of the tranformer. There is also no useable electromagnetic induction to the secondary windings as is the case when AC is transformed. Such a situation will wreck a power transformer in a very short period of time. AC/DC sets If radio manufacturers were going to sell radios in towns that had DC power, they needed to produce a set that would operate on DC and that they did! Not only were suitable DC mains receivers designed but some of these sets would also function on AC power as well. These versatile receivers were known as universal or AC/DC sets because of their ability to operate on either type of supply voltage. A straight DC mains radio is very similar in construction to the AC/DC version, the difference being that the AC/DC model required the addition of a rectifier valve. However, there are a few quite major differences between an AC/DC receiver and an ordinary AC set. First, an AC/DC set has no power transformer. As previously explained, a transformer simply doesn't work on DC so there is little point in having one. Second, some valve types are peculiar to DC and AC/DC receivers in that they have much higher heater voltages. Valves with 25 to GENALEX BC 545 Resurreetion rDE TAVC !"AUDIO T Radio l_ci17fr . ,:'.]lJf 1 1H . c.___ I J 4 $ . I r-ii-1 l I PEAK;:_ . ,. ?00() n I '"" - ~-~ ~ lNT£RM£01ATE rRE'.OlJENCY 4581<C: L---===:::::=::::::t-- -\...-..····~ -.. . . ~ This circuit of an AC/DC receiver is just one of several dozen that are illustrated in the 1938 Radio Service Manual. This suggests that there was a larger market for these receivers than one might think. The barretter tube Now one does not have to be a mathematician to realise that the We have Australia's largest collection of timber and bakelite period radios from 1920-1960. Fully restored and for sale. Prices start from $120.00. All· radios carry a full workshop warranty. llP.GAVCAST SUFSEJU:'.7RllDDTI-.'ll FtlR ..4.C:-D. C-. ◊FZ.Rl\.'l'I◊ll. 35-volt heaters are standard types in AC/DC sets. The reason for these high voltage valves is that the heaters and the dial lamps are all connected in series and such a setup on a 240 volt supply requires valves of higher voltage than the usual 6.3 volt variety. Some of the more common valves used in universal receivers and their heater voltages are as follows: CL2-24V, CL4-33V, CY2-30V, 43-25V, 35Z3-35V, 25Z5-25V and others. Many standard 6.3V valves can also be used provided at least two of the high voltage types are included. VINTAGE WIRELESS SALES SERVICE & RESTORATION collective heater voltages of four or five valves does not add up to 240 volts. Even if connected in series, placing those valve heaters across a 240 volt power supply will ensure their immediate destruction. To save them from such a terrible fate, a "barretter" tube is also wired into the heater circuit. A barretter is a special resistor that is constructed in much the same manner as an early electric light bulb with an Edison screw base. However, instead of a tungsten filament in a vacuum, the barretter has an iron filament in a hydrogen atmosphere. The barretter tube has the ability of maintaining a constant current flow over a wide variation of voltages. One common barretter is the 302. ADDITIONAL SERVICES COPIES OF: CIRCUIT DIAGRAMS $5 .00 SERVICE MANUALS $10.00 AVAILABLE FOR MOST MAJOR AUST. MAKES FROM 1934 ONWARD. WANTED - valves, radios, etc., purchased for cash. Call in to our showroom at: 51 Chapel Street, Windsor, Vic 3181 PO Box 1116 Telephone: (03) 529 5639 The Philips valve specification catalog describes it as a 300 milliamp current regulator with a voltage range of 112-195 volts. When a device such as a 302 barretter is placed in series with a number of valve heaters and dial lamps (which are all rated at 0.3 amps), it gives a reasonably even current flow through the heaters provided the voltage across the barretter is within its specified range + + HT + + 240 VOLTS AC OR DC Vl V2 V3 _r-0 .,. V4 .,. Fig.1: simplified circuit diagram showing the heater connections and high tension supply for an AC/DC set. Note the barretter tube in series with the rectifier's heater. Left: the 302 barretter tube had an Edison screw base and was rated at 112-195 volts and 0.3A. A barretter tube is basically a constant current regulator and consisted of an iron filament in a hydrogen atmosphere. JUNE 1990 23 other valve receiver, requires a high tension DC supply. In the case of DC operation, the set obtains its high tension straight from the DC mains. When operating on DC, the receiver must be connected to the mains so that the anode(s) of the rectifier valve is connected to the positive side of the supply voltage. When on AC operation, the rectifier valve is used to supply the DC high tension. Due to the nature of the design, half wave rectification is used, resulting in the need for a larger than normal electrolytic on the input side of the HT filter. This helps to both reduce the hum and maintain a constant DC voltage. A real shocker The large barretter tube and its special screw socket are one obvious indicator that a set is a DC or AC/DC type . In addition, DC and AC/DC receivers do not have a power transformer, so this type of receiver is easy to recognise. of 112-195 volts. Regardless of variations in the supply voltage (200-250 volts), the barretter will operate well within its voltage tolerance and keep all the valve heaters working at close to the correct voltage. One drawback is that the barretter becomes very hot during operation and so special consideration must be given to its mounting position because of radiated heat. AC/DC radios are very susceptible to noise originating in the power supply and are prone to hum problems. Wiring the valve heaters in a particular order supposedly helps to reduce hum but a study of old circuit diagrams reveals many variations in use. This seems to suggest that maybe it's not all that important. However, the use of radio frequency chokes and numerous capacitors in the power lines indicates the presence of mainsborne interference that requires special filtering techniques. An AC/DC receiver, like any AC/DC receivers are fitted with a special power plug and socket. Note that the two plug connections are different sizes so it will only fit one way. Reversing the plug connections can lead to a situation where the radio chassis has a 240 volt AC potential. 24 SILICON CHIP Now one of the problems with AC/DC sets is that they can be very dangerous to work on. Incorrect wiring at either end of the power cord or the power point itself can give the set a live chassis with a 240 volt AC potential. For the unsuspecting, that can be a real shocker! Because of the fact that a live chassis is always a possibility on AC operation, AC/DC receivers are well insulated to prevent electric shock. These radios are always totally encased with closed backs and all controls fully insulated from the chassis. Even the screws that hold the chassis into the cabinet will be insulated from the set so as to prevent trouble. This large high tension choke could be easily mistaken for a power transformer by someone not familiar with valve radios. This unit came from a Healing AC/DC receiver. Before working on a universal receiver, the chassis potential should be checked using an AC voltmeter, with one probe on the chassis and the other to earth (careful - don't touch the chassis). If the chassis is live (ie, at 240V AC), then check the power cord the active side of the power supply should not go to the earthy side of the receiver. It is also a good idea when working on these radios to use an isolation transformer in the power supply. BOOKSHELF New text on video cameras One out, all out One unusual problem associated with servicing a DC or AC/DC set is the "one out all out" syndrome. In other words, should any valve heater or dial lamp filament burn out, it effectively puts everything else out too because they are connected in series. In such a case, all the valves, dial lamps and the barretter will need to be checked to find out which one is at fault. It may save time to start with the dial lamps. Some circuits have resistors across the dial lamps which lowers their operating voltage and reduces the likelihood of them burning out. In contrast, parallel connected valve heaters are unaffected by an inoperative dial lamp. A well restored AC/DC set should work as well as any standard receiver and about the only difference one is likely to notice is a much longer warm up time due to the current restricting barretter. Because the barretter will only pass a maximum of 300 milliamps, the warm up time is considerably longer. While sets of the DC and AC/DC variety were common only in some country areas, they can show up just about anywhere . Always remember that this particular type of radio can be a dangerous proposition for the unwary, so make sure that you know what you are doing before you plug it in and start tinkering. At the very least, make sure that the power cord is in good condition and check the wiring at both ends of the cord. Then, when you do plug in, check the chassis for 240V as described previously. 1§:;] Video Cameras: Theory and Servicing, by Gerald P. Mc Ginty. Published 1984 by Howard W. Sams & Company, Indianapolis, Indiana. Soft covers, 279 x 217mm, 263 pages. Price: see text. Books on video cameras are few and far between but when they do arrive they are very welcome. This one has been written by a long time practitioner in the field and, since the copyright is owned by Matsushita Electric Corporation of America, it not surprisingly leans heavily on examples of cameras made by that company. Two subjects are not covered in the text, so we might as well mention them at the outset. Since it is an American text, it covers the NTSC system well but makes no mention at all of the PAL system used in Europe and Australia. Second, it makes only the slightest of mentions of CCD cameras which probably account for the vast majority of video cameras now being sold. At the time it was written, CCD imagers would have been very new. Having dispensed with what the book does not cover, we can say that the rest of the subject of video cameras is treated very well although it is more of a theory and circuit practice text rather than one devoted to servicing. At any rate, it is quite difficult to service almost any video camera if you don't have the service manual. So you could hardly expect it to be very strong on this aspect. To give an idea of the subject coverage, we'll list the 19 chapter headings: Elements of Image Conversion, Vidicon Contruction, Beam Focus and Deflection, Vidicon Characteristics, Other Pickup Tubes (Plumbicons, Newvicons , CCDs etc ), Lenses and Light Values, Basic Black and White Camera Adjustment, NTSC Colar From the Camera Standpoint, Colar Dissectors,. Preamps and Gamma Correction, Signal Processor, Enhancement, Encoders, Automatic Light and Beam Control, Sync Generator, Camera Interface and Accessories, Three-Tube Camera Alignment, Single-Tube Camera Alignment, Troubleshooting. In addition, there are two appendices, one on IRE units and the other on coax cable. The text is well-written and there are lots of diagrams and photos to illustrate it. As one of the very few (if not the only) available texts on this subject, we can thoroughly recommend it. It is available from all Jaycar Electronics stores (Cat. BS-0402) at around $36.00. (L.D.S). Wanted: Your Circuit Ideas Have you got a good circuit idea languishing in the old brain cells? If so, why not send it to us for publication in Circuit Notebook and earn yourself some money? We'll pay up to $70 for a really good circuit, depending on how much work we have to do to knock it into shape. So transfer your idea to paper, write a brief circuit description and send it to SILICON CHIP, PO Box 139, Collaroy Beach, NSW 2097. JUNE 1990 25 __ _ _ . ·-· ··---· .. ._, .. , ._,_,_...,,, , .... ,~,...,..-,,, ....rn, '-'-'-v111v1·uv~vn1vnn cLCVlnUl'i lL,u.JATLAH t:Lt.G IHUNIC~AYCAH CLECTRONICSJAYCAR t: LtCIHONIC, R ELECTRONICSJAYCAR ELECTRON ICSJAYCAR ELECTRONICSJAYCAR ELECTRON ICSJA YCAR ELECTRONICSJAYCAR ELECTRO NICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONIC: R ELECTRONICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECrnONIC: R ELECTRONIC:" JAYCAR ELECTRON ICSJA YCAR ELECTRONICSJAYCAR ELECTRON ICSJA YCA R ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRDNIC: R ELECTRO NIC~ JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTR O NICSJAYCA R ELECTR ONICSJAYCAR ELECTRONICSJAYCAR ELECTRO NICSJA YCA R ELECTRON IC:SJAYC:AR ELECTRONIC: R ELECTF R ELECTF R ELECTF '1 ELECTF g ELECTF gELECTf ~ ELECTF '1 ELECTF '1 ELEC TF '1 ELECTF '1 ELECTF These were included in our 1987 Catalogue and were selling for $39.95 each. 1 ELECTF We have obtained a quantity of new (removed new from brand new equipment) 1 ELECTF We have purchased the entire quantity from the importer who was told to clear all stocks at any computer switchmode type power supplies. They have outputs of +5V 2A. +12V 30mA. • 1 ELECTF price! 12V 30mA. & 12V 2A. The probler,. is that they are 110V powered and NOT 240V. You 1 ELECTF The unit is not the most accurate in the world, but it will give you some idea of the pH and can use them for parts at this bargain price. Cat. MP-3000 1 ELECT[ Chlorine levels. The two probes are inserted in to the water to be tested. An instant reading of the l ELECTF Chlorine level and pH value is given on the panel meter display. • l ELECTF We emphasise that this offer is more a bargain for the parts. The meter for l ELECTF example. is worth $10 alone. The case/probe l ELECTF could be used for all sorts of things I l ELECTF l ELECTF Cat.OM-6135 l ELECTF l ELECTF l ELECTF I ELECTF I ELECTF I ELECTF I ELECTF I ELECTF I ELECTF I ELECTF Machine Pin Type I ELECTF 16 Pin normally $1.50 each : ELEC TF Solder Type Now 3 for $2 Save $2.50 ' ELECTF 20 Pin normally 481'- each Cat No. PI 6456 ELECTF Now 16 for $2 Save $5.68 18 Pin normally $1.65 each ELECTF Cat No. PI 6504 Now 4 for $2 Save $4.60 ELECTF Cat No. PI 6458 28 Pin normally 70/t each ELECTF Now 14 for $2 Save $7.80 ELECTF 20 Pin normally $1.90 each Cat No. PI 6507 ELECTF Now 3 for $2 Save $3.70 ELECTF 40 Pin normally 70\', each Cat No. PI 6460 Don't miss this one. Massive scoop purchase of this ELECTF Now 10 for $2 Save $5 Primary • 220V 50hz (wi II work OK on 240V) lead length 1.8mt 22 Pin normally $2 each ELECTF useful IC gives you audio at a long• bare ends ( no 240V plug supplied). Cat No. PI 6508 Now 4 for $2 Save $6 ELECTF Secondarys • 16V AC at BOOmA bargain price! This device sells Cat No. PI 6462 ELECTF • 9V AC at 1.5AMP elsewhere at $4.99, but from us only 24 Pin normally $2.30 each ELECTF Lead length 1.7mt long terminated in a $2991 Now 3 for $2 Save $4.90 ELECTF strange plug Each IC is supplied with technical Cat No. PI 6464 ELECTF Supplied in a maxi box style. Measures 75 (W) x 85 (L) x 60 info and circuit to enable you to ELECTF (H)mm 28 Pin normally $2.60 each build an amp that will give up to ELECTF Now 4 for $2 Save $8.40 ELECTF 10W rms into 2 ohm (from 16V) or Cat No. PI 6466 ELECTF 6.5W into 4 ohm from the same 40 Pin normally $3.25 each ELECTF supply. Now 3 for $2 Save $7.75 ELECTF Cat. ZL-3820 Cat No. PI 6468 ELECTF ELECTF ELECTF ELECTF 10+ $2.49 ea ELECTF Spees: • Max DC supply veils 28 • ELECTF Op supply volts 18 • Output peak ELECTF This is the same as the 'firefly' lighting you saw all over the country during 1988 current 3.5A • Power dissipation ELECTF Bicentennary. Save $20 over the original system we sold in 1988. The cable simply 15W • Min load impedance 1.6 ohm ELECTF pushes into the lugs under the globe housing and a slide clip arrangement holds the ELECTF • Short circuit protected • Thermal bulb firmly. ELECTF protected. Cat. SL-2800 ELECTF ELECTF ELECTF ELECTF ELECTF Cat. MM-2002 (up to 25 globes) ELECTF ELECTF ELECTF ELECTF ELECTF ELECTF ELECTF ELECTF ELECTF ELECTF ELEClf ELECTF ELECTF ELEClf pH CHLORINE METER SWITCHMODE POWER SUPPLY Unbelievable Distress Stock Purchase Unbelievably cheap but there's a catch! $ NOW ON LY WAS $39.95 each $9.95 EXPERIMENTORS PLUG PACK BARGAIN 1-9 $5.95 10-49$5.50 50-99$4.95 100 +$4.50 • S 9 9 , .• 8 Watt 12V Audio Amp IC $2.99 Techlite Bulbs • Low Voltage Lighting System 10 BULBS/BASES $12.95 CABLE TO SUITcatW8-110055~ metre POWER SUPPLY 1 AMP TRAN SFORMER $10.95 2 AMP TRANSFORMER $16.95 ELECTF 100 assorted LED's 5 ELECTF Normal value about ELECTF ELECTF Cat. ZD-1696 ELECTf ELECTF ELECTT El.ECTF C:: LEC Tf C:: LEClf cLEClf cLECTf : LECTF : LEC TF C:: LECTI " LECTI : LECTHv1"111vvv.M. 1VM M c v I nv1 1 MI v1··m cLECTRONICSJAYCAR ELECTRON ICSJAYCAR : LECTRONICSJAYCAR ELECTRONICSJAYCAR : LECTRONICSJAYCAR ELECTRONICSJAYCAR cLECTRONICSJAYCAR ELECTRONICSJAYCAR CLECTRONICSJAYCAR ELECTRONICSJAYCAR 1 .5 Volt Battery Testers The latest in battery testers. Consists of a very flexible piece of plastic with a conductive strip on the rear. Simply place over the battery terminals and the indicator will show if the battery is good, reasonable or bad. Re-usable. Every desk drawer, workshop, toolbox needs at least one. And at the price who cares. 5 different designs available. Cat. SB-2350 ONLY $8.95 rv,-..r1 ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR CLCV I n v 1'1 Vv,Jf-\ TURNYOUR SURPLUS STOCK INTO CASH!! Jaycar will purchase your surplus stocks .of components and equipment. We are continually on the 1ookout for sources of prime quality merchandise. CALL MARK HARRIS OR BRUCE ROUTLEY NOW ON (02) 747 2022 t.Lt.l.., I HUN1\,.;b,,JA Yt;AH tLt t; I HUNIC~JA YCAH CLCCTRONICSJAYCAA ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRO NI CSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRO NI C S J ~ 1 r . s IAYCA9 '" ~rTo"""" J"-" v~ • n c ,_c~~ ~~ - - · - CLCV I M.Ul'ill.,VVM t L,AH CLCL.. I HUl'i lL,~ATL,AH ON JC: NIC: ELECTRONIC ELECTRONIC ELECTRONIC ELECTRONIC ELECTRONIC. CAR ELECTRONICSJAYCAR ELECTAONI CSJA YCAA ELECTRO N ICSJAYCAR ELECTRONICSJAYCAH l:Lt<.; I HUNIL,;SJA YL,A.H t:.Lt:.L, I HU l'\I IL.,.-:)J/-\ JL,Mn CLC\J I nv1 -t1v.,;;iv,.... • vr, , 1 LLLsv , , , ..., , .,...,..., J I-\, ::AR CAR ::AR ::AR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRON ICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRON ICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR \[:();:::::-:,:-:•:•:•:•:•:•:•:•:•:•:•:•:•:•:•:•:•:•.•:•:•:•:•:•:•:•:•.-:-:•,•:•:•:•.•:•:•:•:•,•:•:•:•:•:•:•,·,·,·,·,·:·.·. L,Mn CL CL, 1nu JAYCAR JAYCAR JAYCAR JAYCAR •.•.•.•=·-•-•.•-•:.'•.•.•=·=•-•.-.•.•-·=·= FULL DETAILS SEE PAGE 61 -1990 JAYCAR CATALOGUE UHF Wireless Security System Just imagine a security/alarm system that does not need wires to connect the PIRs, window/door reed switches, personal remote control and optional remote keypad. The only wiring required is to connect to a horn speaker. - IN EW UHF 303MHz Microprocessor Control Wireless Security Alarm System COMPLETE SYSTEM includes 1 x Control Panel 1 x Passive Infra Red Detector/Transmitter 1 x Door/Window Reed Switch/Transmitter 1 x Hand Held Remote Control/Transmitter 1 x Horn Speaker - 10 watt/wired 1 x 240V AC adaptor 1 x 1.2Ah Back-up Battery 1 x Set of batteries for all transmitters " 1 - - - ,,I . - ·· : Cat. LA-5200 ONLY $599 OPTIONAL EXTRAS •Door/Window Reed Switch - Wireless Cat. LA-5210 $69 ., ~ : L,r ! 1 : ,...._ ...._ ,;J ' • Wireless Remote Keypad Cat. LA-5215 $129 • Wireless Passive Infra Red Detector Cat. LA-5205 $149 ELECTRO ELECTRO ELECTRO ELE<;:TRQ CTRO CTRO CTRO CTRO CTRO CTRO CTRO CTRO CTRO CTRO CTRO CTRC CTRC CTRC CTRC CTRC CTRC CTRC CTRC CTRC CTRC CTRC CTRC CTRC CTRC CTRC CTRC .CTRC CTRC .J? g~~ t':Jm::::::zm::zm:::::z::~~. ::::; . . ·.·m.-.·.m•.-.·m.-.·.m•.-.-: : :.-.-.-m.-.•.m·.--m--:: : z: ~~m·.-.m•.•.-.: z·.-..... .-mm ..·. m.·.·.m·.~:::::z::mm~~mm,:r".,W[S:mmmmmm~~~mm~~~~mm~~~mmmmmm~~~::::::::::~z ECONOMY MODEL MULTIMETER cTRc CTRC CTRC CTRC CTRC CTRC CTRC CTRC TRC 'TRC TRC FREE POWER WITH SOLAR CELLS 0.45 VOLT MODULES Ideal as a first meter. Compact enough to fit into the glove box in your car. • 2,000 ohms/volt • Mirror scale to prevent parallax error • Complete with test leads and instructions • DC & AC volts 0-10, 50, 250 & 1000V • -10 to+22dB • 0-1 OOmA current • 0-1 M ohm (2 ranges) • Measures 90 x 50 x 80mm • Battery included Ideal for experimenters. Connect in series or parallel if you wish. Terminal strap enables easy connection to other cells. TWO HANDY SIZES 0.45V 400mA Size 96 x 65 x 6mm TAC Cat. ZM-9005 TRC $3.95 TAC TRC TAC TAC TR< TR< TR< TR< TR< TR< TRI TRI TRI TR< TR< TR< TR< TR• TR• s18.50 NORMALLY JUNE ONLY $15.50 Size 96 x 65 x 6mm Quality cell with aluminium picture framing around the edges. Resin covered. Size 327(L) x 165(W) x 18mm thick. Cat. ZM-9009 Cat. ZM-9007 $5.50 $79 NORMALLY $13.95 JUNE ONLY SAVE $4 60-15kHz B9dB/1mt Bohms Owatts RMS 5.3oz Fully weatherproof. Suitable for PA, intercom, security systems. etc. 10 watt 8 ohm. Cat. AS-3180 NORMALLY $13.95 JUNE ONLY $9 ■ 95 lH TR• TH 10+ $9.50 ea TR· cm CTR CTR CTR CTR $11.95 >QUALITY DISCS AT UNREAL PRICES : Another Jaycar direct import. All disks are supplied with envelope. index labels and writeprotect tabs. Remember. these disks might be cheap but they are good quality. We are so impre~ed by the quality we are happy to offer a lifetime guarantee. , '1i~· SPIROMATIC INDOOR ANTENNA For prime reception areas. site on top of your TV. Popular spiral design. 300 ohm cable supplied. Cat LT-3100 .. . $6 ■ 95 <g*-~~Ni'~~~ ,~,Jt $16.95 for 10 SAVE $10 ·,; , FORMAT TO 1.4Mb! ' 2 llyourcomputerhasthenewfonnat sizing then you can store up to 1.4Mb on the one disc. 10 x 31/'l' MF2HD WAS $49.95 Cat. XC-4738 NOW · · -· J···· ..·'~·•~.i-~.l:.~_.:_;:_::.:._:•_:•_:•.=·-=·.=·.:•.:•.:•_: . :-_:..._'.:\. .~ .......:t.:•.: ....~.~.:.:.,.:. >.. . ( CAR ELc...., 1 nv1'ltL,.:>..lf-\ llvf-\11 CL /CAR ELECTRONICSJAYCAR /CAR ELECTRONICSJAYCAR /CAR ELECTRONICSJAYCAR .-fCAB_EI ECTRONICS,JAVCAR .~.. ·.-:.~ -.'..~·•,· · $34.95 L-An cu:v I HUl'-ill\,.,~M TL,t\n CLCV I MVl'll\.,.:>JM l L,AI"\ tLCL, 1 t1Ul'lll...,~M. T\.,Ati t:.Ll: L, 1 HUNIL--::>.JA TL-AH t.LLL, 1HUNIL,~ ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR :en 31/'l' MF2DD 135TPI DOUBLE SIDED/DOUBLE DENSITY Cat. XC-4736 1 /CAR EL }:;:;:;:;:,:,.,..., ..,... _.,._._._....... _._. ·. CTF :• CTF •• .C1F :: .CTF :_ :CTF Cat. XC-4732 $15.95 for 10 SAVE $3 • · \ ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS CTR •: CTR - CTR CTR : CTR • en; 51/4" DSHD 96TPI DOUBLE SIDED/HIGH DENSITY 1/2 PRICE ~\ ,, . $6.50 for 10 NORMALLY $6.95 JUNE SPECIAL $3.50 NORMALLY $9.95 JUNE ONLY SAVE $3 Al.lows you to easily switch between • 51/40 DSDD 48TPI DOUBLE SIDED/DOUBLE DENSITY 2 mputs to your TV. · Cat. XC-4730 Cat. LT-3018 . g~ CTR '= .JK, ,CTF :CTF :CTI :CTI :CTI :CTI :CTI ,CT :CT : CT : CT : CT cCl ECl v,-m cLCL, 1 nu1'11L,.:>.J/'"\ 11....,,-..n cLECl JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECl ELECl ELECl ELECl , .-.-....-~- ~ ..= J"i.....l..A.VrAo Cl r.rTJ:lflt.llrRIAVr.AA r:1 Fr.7 _ . . _ --· .. -- • , ._._._...,,, , ....,, ., ....,v._,r,, ....,,,,, l.. 1...1..."-' ' 1 ,....,,,.,...,....,..,,... IVr\11 1...LLV l f1Ul"11Vv.JM I \..,M.M I:LCV IMVl'ILl...,.:>,.1/\ ll...,/-\11 t: Lt:\.., I 11UNIL,~JAYL;At-i : LECT l1ONICSJAYCAR : LECT l1ONICSJAYCAR : LECTRONICSJAYCAR . LECTl10NICSJAYCAR .EC111 EC111 ECTH ECTR ECm ECTR ECTl1 EC1 11 ECrn FClR I CTR ECJ'R Lem EClR FCTR ECTR ECIR EClf1 ECIR l:C'JR [ CTR EClR ::CTR =crn : ClR : Crr1 ELECTl1ONICSJAYCAR ELECHlONICSJAYCAR ELECTRONICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONI CSJAYCAR El ECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRON ICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAn ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR A 1.5 to 9V DC/DC convertor Ref: EA May 1990 Replace those expensive 9V batteries with an economical 1.5V D cell. Lasts much longer and saves you the cost of the kit in no tirrn. Shortform kit - PCB, potcores, batte1Y holder, heatsink and all electronic components supplied (excluding optional receiver parts) No box or box hardware supplied. Cat KA-1724 :ClJ1 :crn :cm $19.95 Specifications Type: Output Voltage: Output Current: Tracking Accuracy: Load Regulation: Line Regulation: Ripple output Protection: ' CTll ·Cll1 . C111 :cm :crn ·CIR· ,cm, cm ,cm, :cm cm CIH< crn, crn, cm, cm, c111, crn, crn, cm, CTRI CTl1< CTlll CTl1< cm, CTRI CH~< cm, cm, Non First Syllable Dropped Off VOX Relay Kit Ref: Silicon Chip April '90. At last a VOX (Voice Operated Relay) that does not cut off the first bit of speech! This clever project uses an acoustic delay to prevent the common fault in all but the most expensive VOX circuits - the lOmS or so of that is lost by relay operating time. It may not sound much but it is velY annoying and a long time in speech terms . This kit is supplied by Jaycar in a short form, i.e. without case, front panel, plug adaptor etc. This saves you over $20 on the price otherwise. as we believe most of these projects will be built into other equipment anyway. All other parts (including all PCB parts) included. l:LLCH~ONICSJAYCAI{ ELF':Tfl()NICSJAYCAR EL[CTf'C -' f(,. , JA'fC,'.'.'. ELECTRONICSJAYCAR ELECTRO NI CSJAYCAR ELECTRON:cs... ELECTflON ICS, ~LECTRON ICS, ELECTRONICS, ELECTRONICS .. Ref: Silicon Chip April '90 This magnificent switchmode type laboratory power supply has great professional features but costs around 1/2 of inferior built up units. This kit features high efficiency toroid power transformer, professional high resolution 10turn wire wound voltage control potentiometer, latest I.C. technology, excellent line load regulation, low ripple voltage, apart from a smart plastic case! (for more information see specs below). The Jaycar kit is complete down to the last nut and screw as well as all hard-to-get I.C.'s. CatNo. KC-5073 Box not supplied tLtC I HUNIC::;JAYCAH ELECTRON ICSJAYCAR ELECTRON ICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ± 50V (0-1 00V) 1.5A Dual Tracking Power Supply Kit ONLY : CTl1 .cm ELECTRONICSJAYCAR ELECTRONI CSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR $229 . Dual tracking with switchmode pre-regulators for high efficiency 0 to+/-SOV l.7A from Oto B7V, 1.5A at 91V 1A at 100V Better than 30mV Better than 500mV at +/-V and 1A Better than +/-5mV for mains voltages from 220-26CW AC Less than 3mV p-p at full load Fully protected against output short circuits and forward and reverse voltages connected to the output; fuse protection for the power transformer Only $59.95catK C-5074 Specifications Signal delay: 16.4 miliseconds • Clock frequency: 15.7kHz • Frequency response: 1OOHz to 43kHz within (pm) 3dB • Maximum output signal: BOOmV RMS • Maximum input sensitivity: 0.7mV RMS (to actuate relay)• Harmonic Distortion: <0.5% at 250mV and lkHz <1.5% at 800mV and 1kHz • Signal to noise ratio: (ms) 66dB unweighted with respect to 500mV RMS at the output LEAD ACID BATTERY CHARGER Ref: Silicon Chip March 1990 Comprehensive battery charger for GEL batteries. Charges both 6 & 12 volt batteries. Charging ra tes: · 1.2Ah (250mA); 2.5Ah (520mA); 4.5Ah (900mA); 6Ah (1 2A); 15Ah (3A) Charges our range of GEL batteries. Includes PCB and all board components. No box or front panel. Transformer not supplied: 1.2Ah-4.5Ah use MM-2008 $18.95 or 6Ah-15Ah use MM-2000 $37 95 Cat. KC-5071 PRO SERIES 1 POWER AMP 140 WATTS RMS PER CHANNEL Ref: EA Dec 1989/Jan 1990 NEW - upgraded design - now gives 140W rms channel into B ohms. Dual toroidal transformers supplied. Cat. KA-1725 $599 $69 ::;111, :Tl1< :rn, VHF Powermatch Mk II :;1111 :;1 11, Ref: EA July 1990 Measure RF volts, power SWR and impedance well into the UHF region The Jaycar kit is shortform in this instance. All specified components EXCEPT the diecast case a11d bracket. labels, etc., is supplied. The diecast case, Cat HB-5016 is available separately for $25.95. • Ki t (shortform) Cat KA-172B :;rn, :;m, :;rn, :;rn, :;m, :;1R, :TR• ONLY $39.95 :;rn, :;m, :;m ;m :m :rn ~IH ;1n, !i~: ;i;rn,]: :rn, ;m, :TR• :m :1 R< :TR< ;,n, :rn, :m :111, ;~: ADELAIDE STORE NOW OPEN 190 Wright St e t , p h: ( Qre 8) 2 31 7355 Children are encouraged to learn to compose music. spell, learn maths and play strategic games all on their own without supervision 11 Ca t. XC-3050 NORMALLY $69 SAVE $30 ONLY $39 1. 2. 3. 4. 5. 6. 7. Memo1YTune Math Quiz Multiplication Quiz Am I Correct - math practice Begins with - first spelling Spelling Guess That Letter- auto or program manually B. GuessThatWord-autoorprogrammanually 9. Letter Finder 10. NumberFinder LECTRON, TR ;,l;;ii,i;iiiii1iiii,i;iiiii1iiii,i;iiiiiiiiiiiiiliiiiiiiiiiiiii1iiii,i;iiiii1iiii,i;i~ii,i;i~iiii1ii.a ~ ~ ; ; ~ ~ ~ ~ ~ ; ; , ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ; ; , ~ ~ ~ ; ; - ; ; ; ; ; ; ; ~~ ~ ~ ~ - - = •LECTRONI TnUNJC~JAYCA!if\ YGAl1 l.:LL.L I t1U l\l ll.,b.JA Y-1....,Af1 t.LCV I t1Vl\/ll...,.:>JA n...,A t1 CLCl., I 1'1 U l'l ll...,.:>,JI\ rvAn C.LCV I ,,vl\/11...,,V J .M. I VM.11 L:LCV l 11 U l ~ IV0.JM 1 vr,n LLL\.., I nUl"11V..>..IM I 1...,,--,,n LLL'v I r"'\Ul"1 11...,0Vt-\ I \..,f\11 LECTRONI TRONICSJAYCARAYCAR ELECTnONICSJAYCAfl ELECTf10NICSJAYCAF1 ELECTRON ICSJAYCAl1 ELECTnONICSJAYCAll ELECH1ONICSJAYCAl1 ELECH1ONICSJA YCAR ELECH1ONICSJAYCAH ELECTHONI TnONICSJAYCARAYC/\F1 ELEClRONICSJAYCAR ELECTRONICSJAYCAR ELECTnONICSJAYCAR ELECTnONICSJAYCAl1 ELECTRONICSJAYCAF1 ELECTRONICSJAYCAl1 ELECTnONICSJAYCAR ELECTRON! l f1ONICSJAYCARAYCAf1 ELECTHONICSJAYCAf1 ELECTRONICSJAYCAn ELECTl1ONICSJAYCAR ELECTF1ONICSJAYCAl1 ELECTRONICSJAYCAR ELECTliON ICSJAYCAR ELECTRONICSJAYCAn ELECTHONI T nr-.1\ ll r C"' 1.\Vr' ,.._ n AVr'II [") t= I i::r· TOnl\ llrC'. 11\VrtiD i::1 i::rni nr--11 rc: 1.t.vr·An != I 1=r· n~n ,,.11r., 1AvrAA FI r-rTA()N lr~. IAYCA f~ FI FCl noN ICSJAYCAR El. FCTHON ICSJAYCAR FLECTRO1'JICSJAYCP.R r: 1 FCTRO N[ "'l\..,l"\f"l LLL.._, ,, ,._, , ,.,,._,,._, - • • \YCAR ELECTRONI CS \YCAR ELECTRONICS \YCAR ELECTRO NICS \YCAR ELECTRONICS JAYCAR JAYCAR JAYCAR JAYCAR ELECTRO NICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTR ONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTR 0 NICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAH ELECTRONICSJAYCAR ELEC TRONI CSJAYCAR ELECTRONICSJAYCAR :;:;:;:::••······ 30 Piece Engineer's Driver Set tLtl.- 1KUN!l.,;,J/\ H ,A t"I CLC L, ,. ,v,,, e,0vn , v n " LL L v ,., v , . , v _, . , _ , ELECTRONICSJAYCAR ELECTRON ICSJAYCAR ELEC TR O NICSJAYCAR ELECTRONICSJAYCAR ELECTF ELECTRONICSJAYCA R ELECTRO NICSJAYCAR ELECTRONICSJAYCAR ELECTRONI CSJAYCAR ELECTF ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTF H:Ll 1ELE At last! A driver set incorporating those obscure shaped heads! Have you ever needed recently to service an electric tool? Chances are you would not have been able to do so because the screws holding the appliance together had strange shaped heads. Well now you can with our 30 piece driver set! This set contains all the driver bits you are EVER likely to encounter. (See below). Basic to the set is an 81/2' Chrome-Vanadium driver which will accept any of the 28 hardened steel bits supplied. They are held into the socket of the driver by a small magnet· so you can use the driver in any position. The screw together hollow handle will hold sENeral tips so you don't have to take the whole set with you into the field. There is a tip here to suit almost any screw/nut you may come across. ...•, Here's what you get: • 5slottedbits0-1 , 3-4,5-6,8-10, 12 • 5 hex bits 3/32', 5/64', 7/64", 1/8', 9/64' • 4 Philips bits No 0, 1, 2 & 3 • 4 square recess bits No 0, 1, 2 & 3 • 6 Ton< bits T10, T20, T25, T30, T40 • 2 Pozidrive bits No 1 & 2 • 1 x 1/4' drive socket adaptor • 1 x 1/4' drive hex bit holder And it's all housed in a sealable tough plastic case. Cat TD-2000 1 El AUTORANGING :::: TRUE RMS Ii 3. 75 DIGIT METEX Ii J10" woofer 14/8 ohm 200W rms Cat. CW-2145 $179 ii Dome midrange 1 El • Inductance • Capacitance • Frequency • Temperature • Peak hold • Logic See catalogue for full details Cat OM-1475 $169.50 1 El 1 El HI HI E' E E E E $179 E E E E E E E E E 11 : E 111\ ;z;;::;;;:;;:::::;;;::;;::::::::::::::::::.::::::::::=s ~ i_ID • ,1 4/8 ohm Cat CM-2090 $4 7 ■ 50 Rae al "The Maxwell 1200 Baud Full Duplex (Compatible with V.22 Aus) NOTTELECOM APPROVED ·i•.•-. This stand alon modem is made by Racal-Vadic in the USA. It is capable of lull duplex asynchronous opera lion at 0-300bps (low spCJCd) and 1200 bps (high speed). It has Bell 103/212 (V.22 compatible) capability and has ei ther manual or auto answer capability. It also has auto diagnostics and comes with Auslralian made approved power supply. The price we are asking. of course, is ridiculous. The approved 9-0-9V 13VA (AC) power supply is worth $20 alone and it contains dozens of expensive IC 's insida stylish plastic case. Grab one while they last! Supplied with Telecom plug. SEE SPECIAL NOTE Cat. XM-5052 ·l•i EE Modem" IBM PC Card Modem #2400PC :; :; NOT TELECOM APPROVED This famous modem card fits straight into your PC, XT. etc. It is absolulely complete down to the 72 page instruction manual. internal connection leads and 'George 2.0' system software supplied on 5.25' floppy and 160. page book. With 'George 2.0' you can do all sorts or wonderous things. We have made a scoop purchase of a small quantity of these. Limited quantities. See Special Note Cal XM-5050 lf ll ll ll 11 11 11 11 11 1 1 l s149 l sgg : 1 -l IBM & PC are trademarks of International Business Machines LIMITED QUANTITIES 1 l l -• l MAIL ORDERS HEAD OFFICE P.O. Box 185 Concord 2137 115 Parramatta Road Concord 2137 HOnfNE (02) 747 1888 $10 · $24.99 •. Telephone (02) 74 7 2022 IFOR ORDERS ONLY $25 · $49.99 9 ~ , FACSIMILE (021744 0767 TOLLFREE (008)022888 ~t~R;~~~ I I[ GORE HILL SYDNEY· CITY ' CONCORD VISA 1 El 1 El 1 El I 112" woofer ' i El 1 El 3.75 DIGIT 4000 COUNT 39 RANGE lfifi • Iii }I 4/8 ohm 160W rms Cat. CW-2143 $149 : t HL I jJ 4/8 ohm 120W rms Cat. CW-2142 $99 . HL 1 EL l:J • l;:') !~8" woofer • 1 EL 5/sec sampling ::•••• • Data hold Frequency counter .?= • Diode continuity See catalogue for :::::• full details Cat. QM-1500 $69 · HL HL HL HL Hl ;. 6" woofer Although both modems are capable of operating on Telecom lines they are NOT Telecom approved. They may be used on private telephone line systems. These units are basically being sold as surplus items for the valuable oarts they contain. · LIMITED QUANTITIES 1 EL' 1 El i El El ---------- .,.~------ ------ 1 ELI HL HL / RE/Sponse SPEAKERS !: Dome tweeter $29.50 HU HU HU This fantastic 3 1/2 digit meter is actually easier to use t_ han a conventional hand-held unit. The readout is in the body of the 'probe' itself so you don·t have to avert your eyes to get a circuit reading. The unit has most of the features of conventional meters as welll Logic Probe Bonus. This TTL/CMOS compatible feature will test logic 'HI' or logic 'LO'. The circuit is protected to 250V. All electrical symbols are shown in the large (42mm x 18mm) window. Cat. OM-1420 1 EL :I::'I •• High Power High Quality :: • Dual Impedance 'I See catalogue for full specs. ••• 4/8 ohm Cat. CT-2010 HU HU HU $59.95 $19.95 :• 4/8 ohm P/J'N rms Cat. CW-2140 Probe Type Digital Multimeter 3 1/2 Digits• Manual or Auto Range with Logic Probe HURSTVILLE 117YorkSt.(02)2671614Mon-Fri 8.30 • 5.30 Thurs 8.30 pm - Sat 9 - 12 BURANDA QLD 355 Church St (Cnr. Victoria Rd) (02) 683 3377 MELBOURNE-CITY Mon-Fri 9 • 5.30 Thurs 8.30 pm - Sal 9 - 4pm 1 15 Parramatta Rd (02) 745 3077 SPRINGVALE VIC Mon-Fri 8.30 - 5.30 - Sat 8.30 - 12 121 Forest Rd (02) 570 7000 ADELAIDE S.A. Mon-Fri 9 - 5.30 Thurs 8.30 pm - Sat 9 - 4 $ 3.75 $ 4.50 ROAD FREIG HT ANYWHERE 6 ~ 0 INAUSTR~~l:~upto20kg) 6° 188 Pacific Hwy (Cnr. Bellevue Ave) (02)439 4799. Mon-Fri 9 • 5.30 Sat 9 - 4pm 144 Loga n Rd (07) 393 0777 Mon-Fri 9 - 5.30 Thurs 8.30 - Sat 9 - 12 Shop 2, 45 A'Beckett St City (03) 663 2030 Mon-Fri 9 - 5.30 Fri 8.30 - Sat 9 - 12 887-889 Springvale Road Mulgrave (03) 547 1022 Nr Cnr. Dandenong Road Mon-Fri 9 · 5.30 Fri 8.30 - Sat 9 • 2 190 Wright Street (Cnr Selby Street) (08) 231 7355 Mon-Fri 9 • 5.30 Fri 8.30 - Sat 9 - 12 ~SJAYCAFl.----------------------------------------------1111■-■11111111~~1111■1111■-llllll'!""lllll■"!'"..,.III!'~~ cL1:c I KuN,c"-.JA rcA1< 1: L1:c 11<uN1c::;.;/\ YCAH tLtC I HONICSJAYCAH tLtc I HON ICSJAYCAH t Llc I HONI CSJAYCAR ELECTRON ICSJAYCAR ELECTRONICS JAYCAf :;s JAYCAli 1:L1:L-1t<UN1c::;JA Y<..A11 :::s JAYCA R El.ECTRON ICSJAYCAR ~S JAYCAR ELECTRONICSJAYCAR CS JAYCAR ELECTRONICSJAYCAR CS JAYCAR ELECTRON ICSJAYCAR EL[C1 RO NICSJAYCAR ELECTR ONICSJAYCAR ELECTRONICSJIIYCAR ELECTRONICSJAYCAl1 ELECTRONICS.· 'CAR ELECmONICSJAYCAR ELECTRON ICSJAYCAf1 ELECTRONICSJAYCAR ELECTRON ICSJAYCAR ELECTl1ONICSJAYCAR ELECTRONI CSJAYCAR ELECTRONICSJAYCAR ELECTf1ONICSJAYCAR El.EC rRON ICSJAYCAR ELECTRONICSJAYCAR EI.ECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRON ICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTF1ONICSJAYCAR ELECTR ONICSJAYCAR ELECTRONICSJAYCAR 3~~g~; ELECTRO NICS ELEC1 RONI CS ELECTRONICS , ELECTRONICS~~:~~; Multi-sector home burglar alarm Looking for a versatile home burglar alarm? This unit features variable exit & entry delays, alarm driver circuitry, timed & latched outputs, and two separate sector inputs. A separate board allows you to add additional sector inputs as required. By GREG SWAIN House break-ins are still a problem in our major cities, despite the efforts of police and the various Neighbourhood Watch schemes. It's the portable items that the thieves are after, typically VCRs, cameras, power tools and, of course, cash and jewellery. Although the financial losses are 30 SILICON CHIP usually covered by insurance, it's never nice knowing that a stranger has intruded into one's home. The problem is, many homes present a "soft" target for thieves and even those that are securely locked won't deter a professional thief. To stop the professional thief, you need to take more positive measures and an electronic alarm system is probably the best approach (short of turning your house into a fortress). However, to be effective, the alarm must be correctly installed, it must not false alarm, and it must automatically reset after 10 minutes to meet noise pollution requirements. Most householders elect to have their alarm system professionally installed but that's usually fairly expensive. Often, there's not much change out of $1000. And even if you elect to do the installation yourself, a so-called "budget" 4-sector alarm will set you back about $200 (without sensors), although admittedly it will come in a lockable steel case and include provision for a backup battery. Left: this photo shows the alarm module, together with an add-on sector board. Also shown are some of the devices that you can use with the module: a horn speaker, a flashing blue light, and a passive infrared detector. But what if your budget won't extend to a commercial alarm, or you object to paying for fancy features that you don't really need? Most homes require only a basic alarm which is capable of monitoring just a couple of sectors - four at the most. With this project, you can tailor a home burglar alarm to exactly suit your needs. It includes all the essential features of a comprehensive alarm system but at a budget price. What's more, it can be used with a variety of sensors and can be easily expanded as your budget allows. Main features In its most basic form, this new home burglar alarm consists of a single PCB. This board includes two sector inputs and all the control circuitry for the alarm timer, adjustable entry & exit delays, LED status indicators and the siren driver. On its own, this module can form the basis of a very effective 2-sector home burglar alarm. All you need add are a keyswitch [to arm and disarm the circuit), a horn speaker, the appropriate sensors, and a 12V DC power supply. Depending on the sensors chosen, it could cost you less than $200 for the complete installation. The circuit is armed/disarmed using a simple keyswitch and the entry and exit delays can be independently set anywhere from 0-80 seconds using trimpots. This should provide more than ample time to leave or re-enter the house. If either sector is triggered, the alarm will sound for the permitted 10 minutes and then automatically reset. The sector that triggered the alarm is then disabled [to prevent repetitive false triggers in the case of a faulty sensor) but the alarm can still be retriggered by the remaining active sector(s). In addition to the siren output, there are also timed and latched Resistive Loop Sensing One important feature of the circuit is the use of resistive loop sensing. This simply means that 10k0 resistor is included somewhere in the input loop to each sensor. By doing this, the alarm will be triggered if any attempt is made to disable the loop by cutting it or shorting it with a jumper lead. Each sector input stage is identical and can be used with any sensor that has normally closed (NC) or normally open (NO) contacts. These include microwave & infrared detectors, pressure mats, window foil strips, light beam relays and panic switches. In fact, you can use any type of sensor that has a switched output. Fig.1 shows how the various types of sensors are wired into the alarm circuit. The alarm is triggered by either an open circuit or short circuit at a sector input; ie, if one of the sensor outputs changes state. a ·•~™ INPUT (a) NC SWITCHES IN SERIES :~M INPUT (b) NO SWITCHES IN PARALLEL (c) NO ANO NC SWITCHES Fig.1: these diagrams show how to wire sensors with normally closed and normally open contacts. Note the 10kn resistor in the wiring loop. relay outputs. could be used blue light, for timed output switch on a floodlights. The latched output to drive a flashing example, while the could be used to separate siren or Sector board Need more than two sectors? No problem. To cater for this requirement, a separate "sector board" has also been designed. This compact board carries just a handful of parts and has inputs for two extra sectors. You can add as many of these sector boards to the main control module as you like. All external connections to the alarm module are made via screw-type terminal blocks, so installation is easy. Note the 6-way wiring bus at bottom, left. This runs to the optional add-on sector boards. JUNE 1990 31 PARTS LIST 1 PC board, code ZA-1452, 140 x 106mm 2 12V SPDT relays (DSE Cat. S-7120) 1 12-way PC terminal block 1 3-way PC terminal block 2 SPDT miniature toggle switches 2 fuse clips 1 3A fuse 2 2 .2MO horizontal mount trimpots Semiconductors 1 LM339 quad comparator (IC1) 1 4049 hex inverter (IC2) 1 4027 dual JK flipflop (IC3) 1 4060 14-stage binary counter (IC4) 2 4011 quad NANO gate (IC5,IC8) 1 4020 14-stage binary counter (IC6) 1 4516 presettable binary up/down counter (IC?) 1 556 dual timer (IC9) 1 7808 3-terminal regulator 4 BC548 NPN transistors (Q1 ,Q4,05,06) 1 BC328 PNP transistor (02) 1 BD681 Darlington transistor (03) 5 1N4 148 diodes (D 1 ,D2,D3,D4 ,D5) 2 1N4002 diodes (D6,D7) 2 red LEDs (LED 1 , LED 2) 1 green LED (LED 3) 1 yellow LED (LED 4) Capacitors 1 1OOµF 16VW PC electrolytic The sector boards are easily wired into circuit by means of a 6-way wiring bus that's brought out to opposite edges of each board and to one edge of the main board. To add the extra sectors, you simply strap the boards together in daisychain fashion using plastic cable ties and install six wiring links. Note that all sectors, both on the main control board and on individual sector boards, can be wired for instant or delayed triggering. It all depends on how you install a single output diode for each sector. Each sector also features an enable/disable switch and a LED status indicator. The switches 32 SILICON CHIP 2 5 4 6 1 33µF 1 OV tantalum 1 OµF 16V PC electrolytic 1µF 50V PC electrolytic 0.1 µF monolithic .0015µF polyester Resistors (0.25W, 5%) 4 220k0 1 8.2k0 8 1 OOkO 2 2.2k0 4 22k0 5 1 .5k0 2 12k0 1 2700 5 10k0 Test Resistors 1 1 kO (for testing siren) 2 1 OkO (for terminating sector inputs) Sector board only 1 PC board, code ZA- 1453 , 46 x 106mm 2 SPOT miniature toggle switches 1 3-way PC terminal block Semiconductors 1 LM339 quad comparator (IC1) 1 4049 hex inverter (IC2) 1 4027 dual JK flipflop (IC3) 2 1N4148 diodes (01 ,02) 2 red LEDs (LED 1, LED 2) Capacitors 5 1OµF 16VW electrolytic 2 1µF 50VW electrolytic 3 0.1 µF monolithic Resistors (0.25W, 5%) 4 100k0 2 10k0 2 12k0 2 2.2k0 1 8.2k0 2 1 .5k0 allow you to isolate sectors as required. In this way, some areas of the house can be used while others remain active; eg, the internal alarm sectors can be disabled while the perimeter sectors remain active. A LED indicator lights whenever a sector is triggered and remains lit even after the alarm has timed out. It also remains on after the alarm has been disarmed by the keyswitch and goes out only when the circuit is armed again. That way, you can tell whether or not the alarm has triggered in your absence (due to an intruder or a faulty sensor) and take the appropriate measures. No battery back-up To keep the project as simple as possible, the basic control module doesn't include battery back-up. That problem's easily fixed however, and we'll be describing a battery back-up and mains supply board in a subsequent issue. We'll also be describing a keypad entry system. So you can make this project as simple or as comprehensive as you like - it's up to you. Circuit details To make it easier to follow, we've split the circuit into two separate diagrams. Fig.2 shows the sector input & latching circuitry while Fig.3 shows the main control circuitry which includes the alarm timer, exit & entry delay circuits and the siren driver. Let's deal first with the sector input and latching circuitry (Fig.2). As already mentioned, this circuit provides two inputs and is included along with the control circuitry on the main PC board. It is also duplicated on each of the separate 2-input sector boards. Each input circuit employs two op amp comparators wired in a window detector configuration. ICla and IClb form a window comparator for input 1, while IClc and ICld form a window comparator for input 2. Note that the circuitry for each input is exactly the same so we'll just concentrate on the circuitry for input 1. A voltage divider consisting of two 10k0 resistors and a 8.2k0 resistor sets the upper and lower threshold voltages on the comparator inputs. These voltages are + 5.1 V and + 2.BV and are applied to pins 9 and 10 respectively. The remaining two inputs of ICla & IC1 b [pins 8 & 11) normally sit at about + 4V (ie, in the centre of the window) by virtue of the voltage divider formed by a 12k0 pullup resistor, the 2.2k0 input resistor and the 10k0 resistor in the external sensor loop. The comparators employ open collector outputs which means that they can only pull low. Normally, however, the comparator outputs (pins 13 & 14) are held high by a 100k0 pullup resistor and so pin 6 of IC2a sits low. +BV + 10 16VW+ 0.1J +BV 10k 12K 100k N:3a ,,__ _ _ >o''---=t3 C 4027 K INPUT 1 2.2k 7 +" 01 1N4148 QF2--ll---1--14t-+--+---. S + 16VWI: 0.1+ 8.2k ~ GNO +av ~ +BV +BV + 10 16VW+ 12k +BV 10 + 10 16VV.I i J 01! 12 R 10 ~ D2 1N4148 + 10 16VW+ 10k ~ li! "' MULTI-SECTOR BURGLAR ALARM CONNECTION BETWEEN BOARDS SECTOR CIRCUIT Fig.2: the sector input & latching circuitry. ICla & IClb form a window detector. When a sensor triggers, the window detector output switches low and clocks JK flipflop IC3a via IC2a. This toggles Q-bar of IC3a low and, in turn, pulses either the instant or delayed trigger inputs to the control circuit low via a lµF capacitor & D1. IClc, ICld & IC3b function in the same man_ner. Now consider what happens if a sensor triggers and shorts the input to ground. When this happens, pins 8 & 11 are pulled down to 1.2V which is below the lower window voltage on pin 10 of IClb. The output (pin 13) of ICl b thus switches low and so pin 6 of IC2a switches high and clocks JK flipflop IC3a. Similarly, if the input goes open circuit, pins 8 & 11 are pulled to + BV which again is outside the window voltage limits. In this situation, ICla switches its pin 14 output low and so pin 6 of IC2a goes high and clocks IC3a as before. IC3a provides the sector control logic. As shown in Fig.2, its R (reset) and J inputs are connected to the reset and retrigger lines of the 6-way wiring bus. This 6-way bus is linked to the main control circuit and to all other sectors. When the alarm is armed, the control circuit pulls the reset line high for the duration of the exit delay. This prevents IC3a (and the flip flops in the other sectors) from triggering during the exit delay and resets it so that Q is low and Q-bar (pin 2) is high. At the end of the exit delay, the reset line goes low again and, because the J input is normally held high by the retrigger line, the flipflop is now free to toggle. When the sector is tripped, IC3a is toggled by the clock pulse from IC2a and latches its Q-bar output low. Thus, a negative-going pulse is generated at the sector output via the lµF capacitor and diode Dl. Depending on the linking option chosen, this pulse is applied to either the instant (I) or delayed (D) trigger lines of the 6-way bus and triggers the alarm circuit. As soon as the alarm triggers, the retrigger disable line goes low and disables the JK flipflops in the other sectors (eg, IC3b). This prevents these sectors from retriggering the alarm timer while the siren is on and thus ensures that the total alarm period is kept to 10 minutes. At the end of the alarm period, the retrigger disable line goes high again and rearms the remaining sectors. Sector 1, however, remains disabled because IC3a latches and thus ignores further clock pulses from IC2a. This sector is therefore unable to retrigger the alarm and remains in this state until IC3a is reset by rearming the alarm circuit (ie, during the next exit delay). LED 1 provides status indication for the sector circuit and is driven by IC3a's Q-bar output via parallel inverters IC2c & IC2d. Thus, when Q-bar switches low, the outputs of the inverters switch high ahd LED 1 lights to show that the sector has been tripped. The LED then remains on until IC3a is reset. So IC3a has four functions: (1) it disables the sector during the exit JUNE 1990 33 delay; (2) it disables the sector after it has been triggered so that it cannot retrigger the alarm; (3) it stops other sectors from triggering the alarm while the siren is on; and (4) it latches a LED indicator circuit to show that the sector has been triggered. Switch Sl allows the sector to be disabled if required. If the switch is closed, pin 13 of ICl b switches low and pin 6 of IC2a remains high. Thus, when the circuit is armed, no clock pulses can be applied to IC3a and so the sector is disabled. Sl will also trigger the sector if it is closed after the alarm is armed and this provides a useful test feature. Control circuit Now take a look at Fig.3 which shows the main control circuit. At the very heart of this circuit is IC7 which, together with IC4 & IC6, forms a 10-minute timer. IC7 is a 4516 presettable binary up/down counter and has been wired here to count down (pin 10 at GND). Normally, the count is at 0000 which means that COUT (pin 7) is low. Pin 7 of IC7 is coupled to the base of Q4 (via a 22kn resistor] and also drives NAND gate ICBb. Because IC8b is wired as an inverter, its pin 10 output will be high during this time and this holds IC4 & IC6 in the reset condition (ie, with all outputs at logic OJ. In addition, ICBb's output provides the retrigger disable line that runs to the J inputs of IC3a & IC3b in the sector circuitry (Fig.2). IC7 is only free to count down when its carry in (pin 5), preset enable (pin 1) and reset (pin 9) inputs are all low but first a value must be loaded into the counter via the parallel PO-P3 inputs. This is done by briefly taking the preset enable high when the alarm is triggered. Because the PO-P3 inputs are all connected to the + 8V rail, this pre sets the counter to 1111 (15 ]. Note that IC7's Ql-Q4 outputs are not shown, since they are not used in this circuit. When the alarm is armed, the reset pin is normally held low via a 220k0 resistor while the preset enable is controlled by the output of NAND gate IC8a. If a trigger pulse is received from one of the sectors (ie, the alarm is triggered), ICBa's output briefly switches high and loads 1111 into IC7 via its parallel (PO-P3) inputs. GOUT now immediately switches high and turns on Q4 and relay 1 to provide the timed output. At the same time, pin 10 of IC8b switches low and this does three things. First, it toggles latched flipflop IC8c & ICBd, thus turning on Q5 and relay 2. Second, it pulls the retrigger disable line low to disable the sector circuits as described previously. And third, it releases the reset on IC4 and IC6 to enable the clock circuit. IC4 (4060) and IC6 (4020) are both 14-stage ripple carry binary counters and are almost identical, the main difference being that the 4060 has provision to connect external RC components to form an oscillator. In this circuit, the frequency of oscillation is set to 26kHz by the RC values on pins 9, 1O & 11. This frequency is divided by 16,384 Where to buy the kit This project was developed by Dick Smith Electronics and is available from all DSE stores or by mail order from PO Box 321, North Ryde, NSW 2113. You can also order by phone on (02) 888 2105 or, if you are outside the Sydney area, on (008) 22 6610. The kit consists of an etched PC board plus all the on-board components (note: does not include the keyswitch and horn speaker) . Prices are as follows: Main control module (Cat. K-8401) ................... ................ $39.95 Optional sector module (Cat. K-8400) .......................... .. ... $12.95 Postal orders should include another $4.50 for p&p. Please quote the catalog numbers when ordering. Note: copyright of the PCB artworks associated with this project are retained by Dick Smith Electronics. 34 SILICON CHIP (214) at IC4's Q14 output and clocks IC6 which divides by a further 64. This produces a .025Hz clock signal on pin 15 of IC7; ie, one clock pulse every 40 seconds. Each time a clock pulse is received, IC7 counts down by 1 and so it takes 10 minutes (15 x 40 seconds) to go from the preset value of 1111 (15) to 0000. When 0000 is reached, COUT goes low again, Q4 (and thus relay 1) turns off, and pin 10 of IC8b switches high. This resets IC4 & IC6 and rearms the remaining active sectors via the retrigger disable line. Note that a linking option is shown on Fig.3 for the retrigger disable line. Normally, this link should be installed as shown to prevent the circuit from retriggering during the alarm period. However, there may be applications where retriggering is a desirable feature and this can be achieved by isolating the retrigger disable line from the output of IC8b and connecting it to the + 8V rail. In practice, this simply involves connecting the link to point R instead of point N. Siren circuit As well as providing the clock signal, IC4 also provides two signals to drive the siren circuit. These signals are derived from the Q4 and Q5 outputs and are at 1625Hz and 812.5Hz respectively. These signals are gated by IC5a, IC5b and IC5d and switched at a 6.35Hz rate by the Q12 output. When Q12 is high, the 1625Hz signal from output Q4 is gated via IC5b. However, when Q12 is low, pin 3 of IC5c switches high and the 812.5Hz signal from Q5 is gated via IC5a. IC5d gates the signals from IC5a & IC5b and switches transistor stage Qt. This in turn drives Q2 which then drives power transistor Q3 and the siren. At the end of the to-minute alarm period, IC4 is reset as described above and its Q4, Q5 & Q12 outputs all go low. This switches the output of IC5d low and so transistors Ql, Q2 & Q3 all turn off and the siren stops. Exit delay & reset An exit delay is necessary to give you time to leave the house without HORN SPEAKER ... IRELAY1 7 ,-.-----+---------------+BV 1 7 012 04 5 .0015 Q 16 16 10 IC4 10 K4lo Q6 RST 4 15 ~TIMED ~ OUTPUT 13 12 P1 PO 014 3 10k 4 16 P2 IC7 4516 CLK 11 4060 ':' 22k 11 RST 12 .,. RELAY2 I LINK N LINK RL-+sv ~ LATCHED ~ OUTPUT +av 1 10 220k ~----__..__ _ _.....,_ _ _..,__+av VR1 2.2M .,. 14 +12V 13 220k F1 IC9a 556 12 DELAYEDo-_ _ __.;_ 3A 12 i,::.:.......,_ _ _.n..~....n+12v +aV DC 11INPUT ..("'°DY __, .,. TRIGGER +av ENTRY DELAY RESETO----------------=:i.----------. _;_ IC9b GND / PLASTIC SIDE B EOc ~ VIEWED FROM BELOW + 33 16VWJ 0.11 D4 1N4148 1 ARM 05 1N4148 DISARM 0 EXIT DELAY EICII MULTI-SECTOR BURGLAR ALARM KEY SWITCH CONTROL CIRCUIT Fig.3: a 10-minute timer formed by binary counters IC4, IC6 & IC7 is at the heart of the control circuit. IC9a provides the delayed triggering function, while IC9b provides the exit delay by holding the counters and the sector flipflops reset for a set period of time. setting off the alarm. Its function is to disable the alarm during the exit period and this job is performed by IC9b. IC9b is one half of a dual 556 timer IC and is wired as a monostable. Its output at pin 5 controls the reset line to IC7 via D4. Normally, this output is low and thus has no effect on the circuit. However, when the alarm is armed by switching S3 to GND, a negative going trigger pulse is applied to pin 6 of IC9b and to pin 6 of ICBd via a lµF capacitor. This does two things. First, it resets flipflop ICBc & ICBd so that Q5 and relay 2 turn off. Second, it triggers IC9b which immediately switches its pin 5 output high. This high on pin 5 pulls the reset line to IC7 high via diode D4, thus JUNE 1990 35 Fig.4: here's how to install the parts on both the main board and the add-on sector board. Make sure that all parts are correctly oriented and note that D1 & D2 can be connected to provide either instant or delayed triggering (see text). SECTOR INPUTS SECTOR INPUTS r - - - :;;,;-;~ ~ ~~ S3 KEY HORN TIMED LATCHED 12V -------;:~SW~IT~CH~~~§==T==~='='==:i~::j:'::::;-::-7 0 holding IC7 reset for the duration of the exit delay. It also pulls the reset line of the 6-way bus high to reset the sector flipflops (IC3a & IC3b). And finally, it turns on Q6 to light the exit LED (LED 4). LED 3 (armed) also turns on at this time, since its cathode now has a path to ground via its 1.5k0 current limiting resistor and keyswitch S3. The 33µF timing capacitor on pin 6 now charges via VR2 until the voltage across it reaches 2/3Vcc (Vee = 8V). When this happens, pin 5 switches low again and releases the reset lines so that the circuit is now armed. At the same time, Q6 turns off and the exit LED goes out. LED 3 remains on until the circuit is disarmed by switching S3 to the DISARM position. Pin 9 (reset) of IC7 is now pulled high via D5 and the 22k0 resistor associated with LED 3. This holds IC7 reset and thus disables the alarm timer as before. Entry delay IC9a is the other half of the dual 556 timer and is used to provide the entry delay. It is also wired as a monostable which means that its pin 9 output is normally low and the lµF output capacitor is fully charged. When a negative-going trigger pulse from one of the sectors is applied to pin 8, the monostable triggers, pin 9 switches high, and the 36 SILICON CHIP lµF capacitor quickly discharges via its associated 220k0 resistor. The 33µF timing capacitor now charges towards 2/3Vcc via VR1 and this charging period determines the entry delay. When the capacitor voltage reaches 2/3Vcc, pin 9 switches low again and pulls pin 13 of IC8a low via the lµF capacitor and D3. Pin 11 of NAND gate IC8a thus switches high and loads 1111 into IC7 to start the alarm timer as described previously. The lµF capacitor then quickly charges via D3 and the 220k0 and 100kn resistors, and pin 11 of IC8a switches low again to allow IC7 to count down. IC8a is used to gate the instant and delayed trigger pulses. Note that its inputs are normally held high by the 220k0 and 100k0 pullup resistors, which means that the preset enable of IC7 is held low until a trigger pulse is received. Diode D3 is necessary to protect IC8a from the voltage spike that appears on the positive terminal of the lµF capacitor whenever pin 9 of IC9a switches high. Power supply Power for the circuit is derived from an external + 12V source and is fed to a 7808 3-terminal regulator to obtain a + 8V rail. This regulated + 8V rail supplies all the ICs a))d prevents the circuit from self-triggering when the back-up battery takes over after a mains failure. The relays and horn speaker are powered directly from the + 12V rail to ensure reliable triggering and maximum sound output. Fuse Fl provides short-circuit protection for the + 12V supply while the 100µF, 10µF and O.lµF capacitors on the regulator input and + 8V rail to each sector provide supply line filtering and decoupling. Construction Despite the circuit complexity, this project is easy to build and get going. It was developed by Dick Smith Electronics and is available from this company as a complete kit of parts (for further details, refer to the accompanying panel). Fig. 4 shows the assembly details for both the main board and the optional sector board, and shows how they are linked together. The main board is coded ZA-1452 and measures 140 x 106mm. Before installing any parts, check the copper pattern carefully for possible defects. In particular, check for open circuit tracks and shorts between tracks due to incomplete etching. The parts can now be installed on the board. Install the wire links first , then install the fuse clips, resistors and capacitors. Use a digital multimeter to check the value of each resistor before it is in- SUPER JUNE-AUGUST 90 SPECIAL VHF REMOTE CONTROL - EA April 89 With our latest VHF transmitter • Proven reliable unit • Complete Tx kit and PCB with components for Rx kit. Tx battery included UNBEATABLE PRICE $49.90 for the pair EXTRA Tx $17.20 PIR MOVEMENT DETECTOR/ALARM EA May 89 Now supplied with a commercial case/lens/swivel base assembly. The optional interface kit lets you use it as a stand alone alarm, auto light control, auto door opener, etc. SUPER VALUE AT $39.95 for PIR kit $7 .95 for interface components. We can hold this price only for a limited time. PIR DETECTOR/LENS KIT [JI High quality " DUAL ELEMENT" pyroelectrical detector and small wide angle lens. For JUNE/AUGUST only $17.90 the set. Stock up now! THAT'S MORE THAN 30% OFF EHT POWER SUPPLIES The B0681 Darlington transistor is installed with its plastic side facing away from the relays while the leads of the regulator are bent at right angles so that its metal tab sits flat against the PCB. stalled and note the links that sit beneath relay 1, ICl, IC3 and IC4. The link connected to point N (near VRl) provides the retrigger disable option. As shown, this link will prevent the alarm from retriggering during the alarm period (ie, while the siren is on) and this is the option that will suit the vast majority of applications. If you do wish to provide for alarm retriggering during the alarm period, connect the link to point R instead of point N. Note that if the alarm does retrigger during the alarm period, the alarm timer restarts so don't use this option if you intend using a siren output or you could breach noise pollution laws. Now install the diodes. Make sure that they are all installed with the correct polarity and note that D6 and D7 should be 1N4002 types. Diodes Dl and DZ are wired to select either the instant or delayed triggering option for their corresponding sector inputs. If you want instant triggering, connect the anode of the diode to point I. If you want delayed triggering, connect it to point D instead. Fig.4 shows how the diodes are connected to provide instant triggering for input 1 and Slightly used but tested professional units . Fully regulated. Two types, 24VDC-3.5kV DC at SmA and 24VDC-15kV DC at 500mA. Both will work at reduced outputs down to 6VDC. Use for CROs, high voltage testing , night vision tubes , delayed triggering for input 2 but you should wire them to suit your requirements. The ICs and transistors can go in next. Note that IC3 faces in the opposite direction to ICl and ICZ. Push the transistors down onto the experimenting etc. $39.75 - ,3.5kV unit $44.90 - 15kV unit Limited stocks at these SPECIAL prices _ ···: · f_·.. ··. it/ ~,. £; LASER TUBES AT BARGAIN PRICES See our ads in Silicon Chip April 90 and EA May 90. We now also stock a collimator lens assembly which is used to maintain small beam diameter at long distances. $79.00 HIGH ENERGY IGNITION SYSTEM SC May 88 Uses high energy ignition IC made by Motorola. Proven reliable performer. Short form kit includes PCB and all semiconductors with instructions. ONLY $29.90 I MAINS MUZZLER - SC Jan 89 Filters mains and protects against high voltage spikes. Includes 40 joule varistor and AC capacitors. For all electronic equipment. Short form kit includes PCB and all compo nents as shown. SUPER PRICE $12.90 Why not buy two just in case? SERVICEMAN'S SPECIAL 1 0kV Diodes - $2.50 Late model TV tripler - $12.90 '"'.~.,..,.-· ~ ~_,.. ..·~ .. .,,...,'>'$ ~,_.,~,•h OATLEY ELECTRONICS The add-on sector boards carry just three ICs & a handfull of other parts. These are linked to each other & to the main control board by the 6-way wiring bus at bottom. JUNE 1990 37 PO BOX 89 OATLEY, NSW 2223 Telephone: (02) 579 4985 MAJOR CREDIT CARDS ACCEPTED Certttied p&p $4-$6 Aust; NZ add $2 Distri butors: Slightly higher prices may apply. MELBOURNE: ELECTRONICS WORLD - (03) 723 3860 BRISBANE: KINGSWAY ELECTRONICS - (07) 390 2399 The armed, exit & sector indicator LEDs are all mounted on the copper side of the main board, along with the sector disable switches. Mount the LEDs so that their tops line up with the threaded switch collars. board as far as they will comfortably go before soldering their leads and be sure to use the correct transistor type at each location. Make sure that all transistors are correctly oriented. Now install Q3 and the 7808 regulator. Q3 is installed with its metal face towards the relays while the leads of the regulator are bent at right angles so that its metal tab sits flat against the PCB. The top side of the PCB can now be completed by installing the trimpots, relays and the terminal connectors. Construction can now be completed by installing the switches and LEDs on the copper side of the board. Install the switches so that their leads go about half way through the board and check that they are straight before soldering. The LEDs should be installed so that their tops line up with the threaded switch collars (ie, about 22mm proud of the board). Take care to ensure that the LEDs are installed with the correct polarity. The flat on the LED body is adjacent to the cathode (K) lead. Use red LEDs for the sector indicators, a green LED for the alarm armed indicator (LED 3) and a yellow LED for the exit indicator (LED 4). 38 SILICON CHIP The optional sector boards (code ZA-1453, 46 x 106mm) can now be assembled in the same manner (see Fig.4). Don't connect the sector boards to the main board at this stage, however. That's best left until after the main board has been tested. Testing The following procedure should be followed to test the unit: (1). Connect a 10k0 resistor across each sector input (ie, between each outer terminal and GND) and set VRl & VR2 to mid-range. (2). Set the disable switches to OFF (ie, away from the LEDs) and connect the keyswitch and a 12V power supply (a plugback can be used for testing but not to drive the siren at full power). Note that relay 2 may turn on when power is first applied. (3). Switch the keyswitch to the ARM position. Check that LED 3 (armed) & LED 4 (exit) both turn on. LED 4 should then turn off at the end of the exit delay. (4). When LED 4 goes out, trigger a delayed sector using its disable switch. Check that the sector LED immediately turns on and that both relays operate at the end of the entry delay. Check that relay 1 drops out after about 10 minutes and that relay 2 remains latched (ie, outputs 8 & 9 shorted). (5). Rearm the circuit using the keyswitch and check an instantaneous sector. Check that both relays operate as soon as the sector is tripped. Check that other sectors cannot be tripped during the alarm period if theretriggering link is connected to point N. Alternatively, check that the alarm does retrigger and restart the alarm period if the link is connected to point R. (6). Connect the horn speaker via a lkO resistor (to stop you being deafened) and trigger the alarm. Check that the siren operates for 10 minutes when the alarm is tripped. (7). Connect the optional sector boards and check that all sectors can trigger the alarm (don't forget to terminate all sector inputs with a lOkO resistor). Adjust the entry and exit delays to the required periods using VRl and VR2 (you will have to rearm the alarm to check each period). Switching off The sector disable switches & indicator LEDs are also mounted on the rear of the sector board. Finally, remember that once the alarm has triggered, relay 2 and the tripped sector LED remain on even if the keyswitch is moved to the DISARM position. To reset these, first turn the keyswitch to DISARM, then briefly back to ARM, and then back to DISARM again (note: the exit LED will turn on for the period of the exit delay). ~ SELF CONTAINED WIRELESS PIR ALARM SYSTEM MOBILE BABY MONITOR Fully portable two station audio monitor system . Keep an " ear" on your baby, kids , the aged or the sick. 30m operating dist. 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II "'= 127 YORK ST, SYDNEY PHONE: (02) 267 1385 BUSINESS HOURS Mon-Fri 8 .30 to 5 .30 Thursday 8.30 to 7.00 Saturday 9.00 lo 1.00 PLAYMASTER " PRO SERIES ONE" HIGH POWER AMPLIFIER KIT MAIL ORDERS WELCOME P.O. Box 0103 SYDNEY 2000 Fax: (02) 261 8905 Power output: 200watt RMS into 4 ohms Post & packing VISA $5-25. . . $26,$50. . $51+ ... . . .. $3 . .. $5 . $8 ~!~\ Complete kit . . . . . . .... . . . . . .. . only $549.00 STUDIO 200 PRE-AMP KIT ...... ; .... NOW $199 Low noise universal stereo preamplifier Do you have a need for a low noise stereo preamplifier for your magnetic cartridge, tape player or perhaps for microphone use? If so, this unit is the answer. It is based on the economical LM833 dual low noise op amp IC. By JOHN CLARKE & LEO SIMPSON This universal stereo preamplifier will have quite a few uses for audio enthusiasts. Perhaps the prime use will be for those people who have an integrated stereo amplifier which they are quite keen on but which has a phono preamplifier stage which could be improved. That applies to the phono preamplifiers in a great many amplifiers. They weren't designed to give the minimum noise, minimum distortion and the greatest overload margin. In fact, about the best thing you can say about the preamplifier stages in most older amplifiers is that they are still working. By comparison, the performance of the design presented here is far better than most preamplifiers in most stereo amplifiers - that's a pretty ambitious statement but it is nonetheless true. How do you decide whether it would be worthwhile to upgrade your amplifier's preamplifier. That is fairly easy to determine. Just set your amplifier's controls to their normal settings and listen for hiss with no record playing. The prototype preamplifier was housed in a metal case hut could be built into an existing amplifier chassis or installed underneath a turntable. Keep the circuit away from power transformer hum fields. 40 SILICON CHIP Can you hear hiss from the loudspeakers (or headphones) at your normal listening position? If so, does the hiss greatly reduce or disappear when you rotate the volume control to its minimum setting. If the answer to both questions is yes, then it is highly likely that your existing preamplifier produces more than its fair share of noise. This new design is one of the quietest ever published so you are sure to hear a reduction in hiss. Even if you don't need to upgrade your existing amplifier's preamplifier, you may still have an application for the design presented here. For example, you may want to run two turntables. If your amplifier only has one pair of phono inputs, you could use this external preamplifier for the additional turntable and then feed its outputs to one pair of line inputs of the stereo amplifier. We have also shown how this preamp could be used with a tape deck which does not have its own playback electronics or where the existing tape preamp is unduly noisy. Finally, this design can function as a high quality microphone preamplifier for use with cassette decks (which normally don't have microphone inputs) or in a public address system. We've housed the universal preamp in a standard metal case but it could be built into an existing amplifier's chassis or installed underneath a turntable. Either way, you'd have to make sure it was well out of the way of the hum field of any power transformer. As it stands, our prototype preamplifier has a power switch and LED power indicator, and four RCA phono sockets, two for the inputs and two for the outputs. The circuit The circuit shown in Fig.1 looks a +15V ,~cr-T' .;,;.i '.i: -. l1 150!l 4T. ENCU WIRE ON FX1115 BEAD 47 lOOpFI. .,. Rl 16k 1¾ R4 390!l 1% R2 200k 1¾ IC PIN NUMBERS IN BRACKETS ARE FOR RIGHT CHANNEL MAGNETIC CARTRIDGE 100! BP .,. Rl on R2 200k 1¾ R4 2DOn 1% NAB Rl on R2 200k 1% R4 390n 1°/, 100.I BP .,. Sl POWER MICROPHONE ~K D1 1N4002 0-0 +15V 12V AC FROM PLUGPACK 1 • 1 16VW • _ ';:{ SENSE - 6 3.3k 0.5W A X LEDl K 7 -15V VO-t-- - - - - - - - - - - UNIVERSAL PREAMPLIFIER Fig.1: the circuit is based on the LM833 low-noise op amp. By changing the feedback network, it can he wired as a magnetic cartridge preamplifier for your hifi system, as a tape head amplifier or as a microphone preamplifier. little odd but we have presented it this way to avoid having to show three completely separate versions of the circuit. So in effect, we have shown just one channel of the preamplifier with three alternative feedback networks: for magnetic cartridge, for tape or cassette deck (NAB), and for microphone. For the magnetic cartridge function, ICla not only has to amplify the signal but must also apply equalisation. It takes the low level signal from a moving magnet cartridge (typically a signal of a few millivolts) and applies a gain of 56, at the median frequency of lkHz. Higher frequencies get less gain while lower frequencies get considerably more, as shown in the accompanying equalisation curve of Fig.2 . To be specific, a lOOHz signal has a boost of 13.lldB while a lOkHz signal has a cut of 13.75dB. The phono signal is fed directly from the input socket via a small inductor, a 1500 resistor and a 4 7µF bipolar capacitor to the noninverting input, pin 3, of ICla. The inductor, series resistor and shunt lOOpF capacitor form a filter circuit to remove RF interference signals which might be picked up by the phono leads. The lOOpF capacitor is also important in capacitive loading of the magnetic cartridge. Most moving magnet (MM) cartridges operate best with about 200 to 400pF of shunt capacitance. The lOOpF capacitance in the preamp input circuit plus the usual 200pF or so of cable capacitance for the pickup leads will therefore provide an optimum shunt capacitance. For its part, the 47 µF bipolar capacitor is far larger than it needs to be, as far as bass signal coupling is concerned. If we were merely concerned with maximising the bass signal from the cartridge, then an input coupling capacitor of 0.47µF would be quite adequate. At 20Hz, a capacitor of this value has an impedance of around 15k0 which is considerably less than the nominal 50k0 input impedance of the preamp. But having a large capacitor means that the op amp "sees" a very low impedance source (ie, the DC resistance of the cartridge) at low frequencies and this helps keep low frequency noise, generated by the input loading resistors, to a minimum. RIAA/IEC equalisation The RIAA equalisation is provided by the feedback components, Rl, Cl, R2 and C2, between pins 1 and 2 of ICla (or pins 7 and 6 of IClb, in the other channel, which is not shown). These equalisation components provide the standard time constants of 3180µs (50Hz), 318µs (500Hz) and 75µs (2122Hz). The phono preamplifier also adds in the IEC recommendation for a rolloff below 20Hz (7950µs ). This is provided by the 0.33µF output coupling capacitor in conjunction with the load represented by the following amplifier's volume control and input circuitry (which is likely to be around 50k0). There is also a further low freJUNE 1990 41 The PC board is installed in the case on four 6mmlong standoffs. It is shown here wired as a magnetic cartridge preamplifier but you can wire it as a tape head or microphone preamp simply by changing the feedback components depicted in Fig.1 (see also Fig.2). Note the use of shielded cable for the connections between the board and the RCA sockets. r quency rolloff, at around 4Hz, caused by the lO0µF capacitor in series with the 3900 resistor. The 3900 resistor sets the maximum AC gain at very low frequencies while the lO0µF capacitor ensures the gain for DC is unity. This means that any input offset voltages are not amplified, which would inevitably cause trouble with asymmetrical clipping and premature overload in the preamplifier. Actually, the magnetic cartridge version of the circuit just described is identical to the phono preamplifier of the Studio 200 stereo control unit, published in the June and July 1988 issues of SILICON CHIP. Incidentally, the mention of RIAA/IEC equalisation above refers to two different disc recording standards. The RIAA standard was originally set by the Record Industry Association of America in 1953. The later IEC variation was recommended by the International Electrotechnical Commission in the 1970s. Specifications Frequency Response Phono version: RIAA/IEC ±0.3dB from 20Hz to 20kHz Mic version: within ± 1 dB from 1 OHz to 20kHz Less than .005%, 20Hz to 20kHz, at 1V RMS Signal-to-Noise Ratio • Phono: 83d8 unweighted (20Hz to 20kHz) with respect to 1 OmV input signal at 1 kHz with 1 kO resistive input termination; 89.5dB Aweighted with respect to 1 OmV input signal and with 1 kO resistive input termination. Separation Between Channels -82dB at 1 OkHz, -88dB at 1 kHz and -80dB at 1 OOHz, with undriven channel input loaded with a 1 kO resistor. Gain Maximum Output Signal 8.4 volts RMS at 1 kHz 42 SILICON CHIP In the tape equalisation version, the value of RZ is identical to that of the phono preamplifier but R4 is now 2000 and Rl is replaced by a wire link. Cl & CZ are omitted and replaced by R3 & C3. Microphone version In the microphone version, RZ and R4 are the same as in the phono preamp while Rl is a short circuit and Cl is omitted altogether. The microphone has a gain of 513, making it suitable for low impedance microphones. If less gain is required, it is simply a matter of changing the ratio of RZ to R4. For example, if you want a gain of 100 times, make R4 4700 and RZ 47k0. Power supply Total Harmonic Distortion Phono: 56 at 1 kHz Tape: 53 at 1 kHz Tape equalisation Microphone: 513 Input impedance: 50k0 Phono Input Overload 1 50mV RMS at 1 kHz The power supply may look a little unconventional but is quite straightforward. It is fed from an external 1 ZV AC plugpack which enables us to keep the power transformer well away from the preamp circuitry. The 1 ZV AC input is rectified by two diodes, Dl and DZ, and filtered by two 470µF electrolytic capacitors to give positive and negative unregulated DC rails of around 21 volts. These rails feed an LM325 voltage regulator IC. This is an economical substitute for a pair of 7815 and 7915 15V 3-terminal regulators. Apart from ,w.4 A 12V AC FROM PLUGPACK S1 RIGHT INPUT Fig.2: refer to the main circuit diagram for the values of R1-R4 and C1-C3, and use the values to suit your application. Take care with component orientation and use your multimeter to check resistor values before installing them on the board. TABLE 1: RESISTORS D D D D D D D D D D No. Value 4-Band Code (5%) 5-Band Code (1%) 2 2 1MO 200k0 100k0 16k0 3.6k0 3 .3k0 3900 2000 1500 1000 brown black green gold not applicable not applicable not applicable not applicable orange orange red gold not applicable not applicable not applicable brown black brown gold brown black black yellow brown red black black orange brown brown black black orange brown brown blue black red brown orange blue black brown brown orange orange black brown brown orange white black black brown red black black black brown brown green black black brown brown black black black brown 4 2 2 1 2 2 2 2 taking up less board space than separate regulators, the LM325 gives better tracking between the positive and negative rails, within ± 300mV. Its output current capacity is lO0mA which is well in excess of the 5mA or so needed by the preamplifier. Construction All the circuitry for the universal preamp goes onto a small printed circuit board measuring 75 x 95mm and coded SC0l 106901. It has the power supply connections at one end and the signal input and output connections at the other. For our prototype, we mounted the printed board in a standard metal case measuring 105mm wide, 65mm high and 150mm deep (Jaycar Cat. HB-5442 , DSE Cat. H-2743). This case has ari aluminium base fitted with four rubber feet and a black crackle enamel TABLE 2: CAPACITOR CODES Value D D D D D 22pF 100pF .0047µF .0 15µF 0 .33µF Alt Value IEC Code EIA Code (10%) 4.7nF 15nF 330nF 22p 100p 4n7 15n 330n 22K 101K 472K 153K 334K finished steel top cover. Before commencing assembly, carefully check the PCB pattern fo r any shorts or breaks in the copper tracks, which should be corrected at this stage. Fig.3 shows the wiring details. Start by installing the 12 PC stakes on the PC board. Once this has been done, you can install the wire links and the resistors. We suggest you use a digital multimeter to check each resistor value as it is installed. The two inductors (Ll in each channel) are made by winding 4 turns of 0.6mm enamelled copper wire on an FXl 115 ferrite bead. Scrape the enamel off the ends of the inductor leads and tin them with solder before soldering them into the printed board. Note that the feedback components in each channel are shown on the boa rd as Rl, R2, Cl , C2, etc. You will have to look at the circuit diagram to see the value for each of these components, depending on which version you are building. JUN E 1990 43 Don't m iss a single issue IF YOU'RE THE KIND OF READER that can't wait to get the next copy of SILICON CHIP, then why not have the magazine delivered direct to your door? Each month, we'll bring you the best and brightest electronics magazine in the business, put together by Australia's most experienced team. Here's what to look for in each issue: * Constructional Projects For The Enthusiast * Amateur Radio: Theory & Projects * The Serviceman's Log * Computer Bits: Getting The Most From Your PC * Vintage Radio: A Sabscr·t, Toda • e y by fillin lllaiJ•1ng gtl)•out and subscript• is -----..............::.:•:o:n~ coupon Fascinating Hobby 24 Hour Fax Service r----------------------Freepost * Subscription Coupon (02) 979 6503 Send the coupon with your Credit Card details. 24 Hours, 7 Days a week. □ □ New subscription Renewal Start in _ _ _ _ _ __ Name _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ (PLEASE PRINT) Subscription Hotline Telephone (02) 979 5644 9am-5pm Mon-Fri and quote your Bankcard, Visa Card or MasterCard No. and expiry date. Detach Coupon and Mail to: FREEPOST 25 SILICON CHIP PUBLICATIONS PO BOX 139 COLLAROY BEACH NSW 2097 *No postage stamp required in Australia. 44 SILICON CHIP Street _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Suburb/town _ _ _ _ _ _ _ _ __ 1 year ( 12 issues) □ $A42 Australia _ Postcode_ _ __ 2 years (24 issues) □ $A84 NZ & PNG (airmail) □ $A65 □ Overseas surface mail □ $A62 □ $A130 Overseas airmail □ $A 1 20 □ $A130 $A240 Enclosed is my cheque/money order tor $ _ _ _ or please debit my □ Bankcard Card No. □ Visa Card □ MasterCard I I I I 11 I I I 11 I I I 11 I I I I Signature _ _ _ _ _ _ _ _ Card expiry date_ _ /_ L _______________________ J r• 7 UNIVERSAL PREAMPLIFIER ~IH/ll- POWER L OUT L IN R IN R OUT • • • • • L ~ _J I PARTS LIST 1 PCB, code SC01106901, 75 x 95mm 1 metal case , 150 x 61 x 102mm 1 Scotchcal panel, 100 x 52mm 1 1 2V 5VA AC plugpack 1 SPOT toggle switch 1 5mm LED bezel 4 panel mount RCA sockets 4 6mm PCB standoffs 12 PC stakes 4 screws and nuts to suit standoffs 2 FX 11 1 5 ferrite beads 1 small rubber grommet 1 100mm length of 0 .8mm enamelled copper wire 1 1 50mm length of shielded audio cable 1 200mm length of light duty hookup wire Semiconductors 1 LM833 dual low noise op amp (IC1) 1 LM325 ± 15V regulator (IC2) 2 1N4002 diodes (01 ,02) Fig.3: here are actual size artworks for the front panel & the PC board. Be sure that the polarised components are correctly oriented on the PCB. These parts include the electrolytic capacitors, diodes and the two ICs. Mount the ICs on the board last of all. Once the board assembly has been completed, check it for correct installation of all the components. You can now connect the 12V AC plugpack to the circuit. Check the DC voltages around the circuit with respect to one of the PC stakes which is at 0V. You should find + 15V present at pin 8 of ICl and pins 1, 13 and 14 of ICZ. For the negative rail, - 15V should be present at pin 4 of ICl and pins 6 and 7 of ICZ. Actually, due to the production spreads in the LM325, you will find that the + 15V rail can be anywhere between + 14.5V and + 15.5V. Similarly, the negative rails should be anywhere between - 14.5V and - 15.5V but the absolute values of both rails should be within ± 300mV. You can also check the offset voltages at the outputs of ICl, pins 1 and 7. The voltage at these pins should be within ± lO0mV of 0V. It will most likely be quite a lot less than this figure. The PC board is now ready to be installed in the case, if that is the way you intend to use it. Before you can do that, you will need to drill the holes for the front panel hardware, the grommet in the rear panel and the four PC pillars. If you are using a Scotchcal front panel, you can use it as a marking template for the front panel holes. Capacitors 2 470µF 25VW PC electrolytic 2 1 OOµF bipolar PC electrolytic 2 4 7 µF bipolar PC electrolytic 2 1µF 16VW PC electrolytic 2 0.33µF metallised polyester 2 .015µF metallised polyester 2 .0047µF metallised polyester 2 1OOpF ceramic 2 22pF ceramic Resistors (0.25W, 5%) 2 1MO 2 200k0 1 % metal film 4 1OOkO 1 % metal film 2 1 6k0 1 % metal film 2 3 .6k0 1 % metal film 1 3.3k0 0 .5W 2 3900 1 % metal film 2 1 500 1 % metal film 2 1000 Note: depending on the version built, resistor values for R1 and R4 will change. The same applies to C1 and C2 (see text) . When all the holes are drilled and the front panel artwork fitted, you can mount the PC board in the case and complete the wiring. When all the wiring is complete, you can switch on and check the voltages again. ~ JUNE 1990 45 PHONEORDER TOLL FREE ALTRONICS 008 999 007 NEW! EXCITING, HERE NOW! Dear Customer, Regrettably, we're a liule late in releasing this FANTASTIC "PRO SERIES ONE" amp. kit. We really tried our utmost to have the kits available in late February. However, some of the materials proved imposiblc to obtain until quite recently. Anyway, after burning the midnight oil, we now have a warehouse full of kits of this remarkable amplifier design. Everyone we've had listen to it is impressed. I'm sure you will too- imagine, 200 Watts per chanuel for less than $6001 Once again we apologise to all our customers who we have let down with late delivery. But, as a "peace offering", we arc offering all our customers $50.00 off all orders placed for this product until June 30th (and_of course to all back orders!) ~ /l //(! ,_ .. _ ~ / Thanks for your pauencc. ~ (Y ~ Playmaster "Pro Series One" High Power Amplifier as been carefully developed to produce a high definition audio output with reonstructlon and low cost. The diecast front panel atslnk. The chassis Is su (See EA December sembles i · Amazing 190W IHF into 8 Ohms! An outstanding high power stereo amplifier for you home HIFI, '89, January '90) Disco, or Live PA system. PERFORMANCE Power Output (per channel w~h both channels driven) Contlnuoua: 140W RMS into 8 Ohm• 200 · Harmonic distortion: 0.005% at 100W RMS into 8 Ohms Frequency reaponae 10 Hz to 100kHz (-3dB points) Signal to noise More than 100dB below rated output (unweighted) naltlvlty 3V RMS for 1DOW into 8 Ohms load Indicator if output distortion ex ) dividual toroidal transfer nnel for low residual hum * Is Digital Recorder de/Ivers astonishing reproduction of voice and/or music without ne single moving part! Digital Voice Recorder __..-- ; ' -~l· \·;,,;;,,- -~ (Silicon Chip Oec'89) ere is a digital voice recorder that can store 4 different signals, voice, sound or a music source of up to 30 seconds each or . ne recording of up to 2 minutes. his new digital voice recorder uses a special voice recorder/playback IC and 7 other IC's making it both simple to construct . nd incredibly economical. eparate 256K Ram chips are used for each channel. These memories can be ganged to provide a total of 2 m,mi.tes of ssage time. There are 4 trigger inputs so that a message can be stored when a certain condition occurs. attery backup is provided so that the messages are retained when main power is off. · · -- · ., yplcal appllcatlona include: • Alarm system messages • Sales messages for customers put "on hold" • Experimental telephone answering , 'I. machine • Door station announcer• Talking displays for shops • Emergency warning message announcement • Operation instructor for machinery etc. For those who want a professional appearance • stand alone product, we can supply with out Deluxe H 0483 Instrument case and fully punched and screen printed front panel. 9550 Kit complete - PCB Format $129.00 $149.oo Speeeh Synthesizer (ETI March '88) Here is a self contained Speech Synthesizer that does not require a computer to control it. This small, simple circuit contains all the necessary cm1poncnts to make your favourite p011euioo.s speak. It can be connected to almost any appliance, \'Chicle or home remote control 1ystcm to let you know when tho kettle bu twitched off, tho doon a,e lockd or the water in the radiator is boiling. The inputs arc coded and priority mcnage reading meam wa.minp arc heard imtead of greetings ctc if two messages arc acnt at the aanz time. Blank Eprom included to allow you to pogram the messages you want K9soo $85.oo S95.00 K 9502 Pre-Programmed Eprom for K 9500 $20.00 FEATURES: • Sett contained circuitry • Simple double-sided PCB • Comes complete w~h speaker and Eprom • 12V DC operation SAVE $10.00 INVERTERSINVERTERSINVERTERSINVERTERSINVERTERS POWERHOUSE 6QQW Get 240V AC Mains Power from your battery with these handy Inverter kit sets Many combinations to choose from: INVERTER (Sec EA Dc<:'87) · invcrlm' hu the capacity to produce 600 watts of maim power which will nm a llmlY of applima,o. Ideally IUimd to running power tools, lighting (including fluroo) electric motan and much more. It can be UICd either aa a pmtable or a permanent fixture. • Manual or Auto Start facilitic1 • Low battery • WITH AUTO START Opcnl£I from 12V Car Battery I Auto Start drawa power from your banery only when appliance is plugged in and "tumcd on" ie, battery can be left permanently c:ormccmd if n,quircd. • Voltage Regulamd • Current Regulamd • Current Overload unit self limits cut-out. Kit version K 6770 $425.00 Complete Kit K 6750 $279.00 Fully built and tested K 6755 $379.00 Fully built and tested 12V Input K 6774 $525.00 24V Input K 6775 $525.00 ioo•s OF USES AT HOME AND AWAY 1 GHz Digital Frequency Meter - ► 30% (See Silicon Chp Nov '87, Jan '88) Thi• auperb 1 GHz Frequency Meter wlll out perform many other Instruments twice its price. K 2515 was 8299.00 NOW8249.00 SAVES50.00 e: • Professionally machined and screen-printed red perspex Easy to assemble • Bright Hewlett Packard 8 digit display • h latching • High perlormanoe IC's • High Qualtty components. Operational Modes: Period frequency to 100MHz freq . to 1GHz Hz to 1GHz (1.7GHz typical) in frequency mode; 10Hz to 2.5MHz in period mode. Gating times: 0.01, 0.1, 1.0 and 10 seconds · , 1.28, 12.8 and 128 seconds (1GHz range) . VIDEO ---- MODUIATORS Video Into RF Australian Channel O- RF zx 00901 to 9 $3.00ea, 10-24 $2.50ea, 25 and up $2.00ea output • QUALITY ASTEC brand Just look at these appllcstionsf • Computer to TV • Video Games • Use TV as remote video monitor • Low Cost C RO adaptor for TV e Video recorder or camera to TV and so on. Completely seK-contained in PC mounting shielded case with RCA connector output.+ 12V supply (case• ve). Single terminal wire video input. Earna ita C06t hunderd• oftimM over In cleaning connecto,., PCB'•• •witche•,}ewellery, gl•••• _,che•, drafting pen•, etc. A-rded the Good .Product O.algn Award for CETDC in 1987 us Pin Point ULTRASONIC CLEANER WIii even clean your teelhl Won't scratch or damage - uscs ordinary tap water and cn::a~ milli0n1 of super-penetrating , bubbles. Hospital tclltll show that : Ultruonio cleaning producca better results aafcr than l ; In JUJt 3 minutes you wlll be amazed at the difference! ·~OFF · a• . SCOOP PURCHASE 19" RACK CASE MAGNIFICENT POWDER COATED FlNISH? HUGE SAVINGS rms MONTH! CAT NO. H 0404 GREY H 4014 BLK H 0405 GREY H 4015 BLK H 0406 GREY H 0416 BLK mm NORMALLY SPECIAL 44X254 88X254 132X254 $59.95 $69.95 $85.00 $40.00 $45-00 $50.00 19" PR.ONT PANEL G.lV.E-AWAY! CAT NO. mm NORMALLY H 0431 GREY H 0434 BLK H 0432 GREY H 0435 BLK H 0433 GREY H 0436 BLK 44 88 132 $U.95 $•3.50 $:&S.95 Digital Multimeter+ This truly fantastic bench Dlgltal Multlmatar + LCR, with capacitance and Inductance ranges, enable you to test a wide variety of components. lndlspenslble for the design engineer, technician and enthusiast allka. DC Voltage: 200mV, 2V, 20V, 200V, 1000V AC Voltage: 200mV, 2V, 20V, 200V, 750V DC Currant: 200uA, 2mA, 20mA, 200mA, 2A AC Currant: 200uA, 2mA, 20mA, 200mA 2A, 20A Resistance: 2000hm, 2k0hm, 20k0hm, 200k0hm, 2MOhm, 20MOhm, 200MOhm . Capacitance: 2nF, 20nF, 200nF, 2uF, 20uF Inductance: 2mH, 20mH, 200mH, 2H, 20H hFE test, Diode test Price Breakthrough Q 1062 $149.oo $12.so Carry Case 01068 SPECIAL $8.00 $9.00 S•8.oo Why pay $400 or more for a David Clark set? AVIATORS HEADSET WITH OIL FILLED EAR CUSHIONS • High pcrfomwioc, noilc attenuating • Noiac cancelling microphone • Cushioned bead pad • Super ltUrdy • Gn:at perfannanco • Superb, profcuional pilot's hcadxt will lut a lifetime with rcuonable -; treatment. • Includes standard airaaftjacb. earphone■ . Y $189.00 c9010ONL Pocket Sized Personal Audio Signal Generator Qu~e the finest portable audio oscillator we have ever seen. Range switch and multiply enable selection to 46 preset frequencies from 20Hz to 150kHz, eg 20Hz, 2BHz, 32Hz, etc. Sine Wave and Square Wave outpuL Output control -20db to Odb Internal 9V battery Now available from ~ Altronlcs Dealers ~LS OURDmECT IMPORT PRICE L ~ THAN $1-00: Q 1542 Oscillator VALUE Q 1544 Protective Carry Case ;_"\-/ " . $12.50 MULTI FUNCTION CAR ALARM WITH WIRELESS REMOTE * Sec EA April/May 89 lnsulatioo breakdown cm in electrical wiring and appliances can be determined with this dual range megohm.meter. Ideal for chcc1<in& imulation in tronaformcn, oppliancos, autC1D.otivc generators and altematcn, boutc wiring etc. B,calcdown can be mcuwed It either SOOV or IOOOV depending on the situation. Perrect ror workvan, toolbox or work bench. K 2555 Wireless remote activate/de-activate alarm system and central door locking system (where fitted). Horn sounds to oonfirm armed. Light flashes to indicate disarmed. • VERY COMPREHENSIVE Comprehensive system protect& from: • • • • Bumping of car body Towing Window breaking Forced entry of door boot or bonnet. HIGH PO\VER CAR ALARM \Vith Wireless Ren1ote Control ~ RED $129.00 HOW ABOUT THIS LITTLE BEAUTY? UNIDEN ROADRUNNER, 5WATTUHF40 CHANNEL CB TRANSCEIVER Passive Infra-Red Floodlight Cont~ol (((W,~ro> ,., High Performance This alarm system will be triggered by unauthorised entrance through the car doors, boot, bonnet or removal of the car sound untt. The siren will sound and the headlights flash for 60 seoonds. Simple wiring, wire it yourself without professional assistance. Automatic Reset One of the most ss220 O N L to come from the UHP stable, this SW HandHeld wcigha in at just 470 gms - including battery pack. Featurea: 9650$799 IOO.O 1H Y $99.00 ELECIRE'J' POWER 1'IlC. How often have you thought there could be a prowler outside your door? Install a Lile Guard & (once armed) any "guest" will be floodlit when detected by thia highly sensitive Infra-Red Detector. Spectncatlon,: • All weather operation • Operation Time, l-20mins • Sensltlvlty: '}J)' - 50', 30 beams• Almable • Switching Capability: 500W max. incandc!ICCnt • Operation Modes: OPP, AlTJ'O, TEST, MANUAL, ON. s 5350 was $135.00 SPECIAL ONLY $99.00SAVE Door switch circuit Dcx>rs,trunk, ,hood e t c . ~~ COUlJl"CI handhold units • 5Watts audio output power • 40 channels • Squelch control • Power Hi/Lo key e LCD displays • Channel UP and DOWN keys • Channel scanning • Repeater channel rogramrring Pos . +Plugs into fuse box BLUE Lite Guard * lOA/ FUSE L-Y;,,:E:::L=LOW::;__ _ _ Headlights Direct Import Price! * -tli• Earth 8.c._LA_CK ....:.. _____ RADIO s 5225 $79.00 VALUE ~ For professional 2 -way radios on aircraft. boats, vehicle• and Industrial PA" ayatema. Fantastic voice clarity, absence of feedback and background noiJe with this microphone . Frequency response: This mouth only $15_oo 'Z FERRO FLUID DOM TWEETER 100mm 60Watts Top end quality 11 a VERY rcuona~c price. C 3012 Normally $29.50 each, Now$15.00 Save $14.50 Buy four c o3o& Normally $29.80 for $50.00 Nearly ball price% 400Hz-8kHz Impedance: 160 Ohms ._ , _ Sensitivity: -65dB (San from sound source) ) , Requires 1.5V battery * Jfl Automatic Charger for Ni Cads INSTALLED IN MINUTES. Connects via P 0995 double adapter to telephone line at existing wall socket. Double adapter accepts both telephone and extension bell, which is supplied with a 10 meter lead. NOT SUITABLE FOR COMMANDER PHONE SYSTEMS... VALUE (See EA July '89) Get 100's more recharge cycles from your nlcads Its now well known that correctly charging nicad cells greatly extends their service life. Here is a fully automatic NiCad battery charger that enables differing charge rates as appropriate for AAA, AA, C, D cells or cells in series up to 9V. Once the battery is charged, the unit automatically switches to trickle charge until you switch it off. p 0996 $29 .50 ~j' -·>" Hot Canaries - The Electronic Canary csmcon Chip Feb'90) Get that atmosphere of tranquility that only birds can give. The realism of this project is remarkable. Sounds for all the world like two trilling canaries. • Battery po-red K165o$39.5Q M 9020 (Plug-Pack Extra) $16.95 *II Bel Express 3 Radar Detector Detects X, Kand the new Ka Photo Radar Band. ew Industry standard! Express 3 contains the latest Bel breakthrough. Image Refection Technology for KA band Photo Radar detection and twice the X and K band sensitivity of ordinary superhet radar detectors. Fully equipped, Express 3 has no equal. NORMALLY $699.00 SAVE $IGO! A1540 Special Introductory price $599.oo 'Z Bel Express 3 - acclaimed the leader in Canada and USA - now available In Australia from Altronic. SPECIAL Prepro gram me d Features ■ Instant On/Pulsed Warning : Encountering radar of this nature results in a warning sequence consisting of a series of quick "beeps" (unlike X, Kor Ka alerts) folio~ by the audio alert that corresponds to the type of radar received. Rashid VASS Rejection : Automatic rejection of signal received from collision warning systems which operate on the same frequency as polioe radar (K Band). Automatic K/Ka Band Override: Express 3 instantly alerts to the presence of K or Ka Band radar when the FSA mode is engaged. Automatic Test Sequence: Each time~• is engaged, Express 3 will sound a single group of X, K, Ka and instant On/Pulsed alerts indicating it is ready to process police radar. ■ ■ ■ PROFESSIONAL QUAU1Y e BANKCARD e VISA e MASTERCARD e PHONE TOLL FREE 008 999 007 e NEXT DAY JETSERVICE DELIVERY Country clients please allow an additional 48-72 hours "" i .' ~ , ,«<i,/ff}~r:! 174 Roe St. Perth W.A. 6000 PHONE TOLL FREE 008 999 007 Perth Metro (09) 328 1599 ALL MAIL ORDERS P.O. Box 8350 Stirling Street Exchange Perth W.A.6000 AL TRONICS RESELLERS Chances are t here is an Altronics Reseller right near you - check this list or phone us for details of the nearest dealer. Pi.... Note: Resellers have to pay the cost of freight and insurance and therefore the prices charged by individual Dealers may vary slightly from this Catalogue - in many cases, however, Dealer prices will still represent a significant cost saving from prices charged by Altronics Competitors. Don't forget our Exprno Mall and Phone Order S.nrlce- lor the coot of a locel call, Bankcard, VI•• or M•tercard holder• can phone order for oame day dnpatch. Blue Ribbon D ..lera are highlighted with a ■. These Dealers generally carry a comprehensive range of Altronic products and kits or will order any required MORE AL TRONICS DEALERS WANTED if you have a Retail Shop, you could increase your income significantly by becoming an Altronics Dealer, Phone Chris Campbell (09) 328 2199 for Details. STANDARD DELIVERY & PACKING CHARGE $5.50 to 1Kg $8 over 1Kg AUSTRALIA WIDE - We process your order the day received and despatch via. Australia Post. Allow approx 9 days from day you post order to when you receive goods OVERNIGHT JETSERVICE Up to 3 Kg is $8.00- 3Kg to 5Kg is $20.00- We process your order the day received and despatch via. Overnight JetHnrlce Courier lo_r delivery next day Country areas please allow additional 24-48 hours . HEAVY HEAVY SERVICE -All orders ol 10Kgs or more must travel Express Road - Please allow 7 days for del ivery. $12.00 to 10Kgs, $15.00 over 10Kgs. INSURANCE - As with virtually every other Australian supplier, we send goods at consignees risk. Should you require comprehensive insurance cover against loss or damage please add 1% to order value (minimum charge $1) . When phone ordering please request " Insurance". · TOLL FREE PHONE ORDER - Bankcard .Visa. Mastercard Holders can phone order toll free up to 6pm Eastern Standard Time. Remember with our Overnight JetHnrlce we deliver next day. item for you . WA COUNTRY ALBANY BP Electronics ■ 412681 ESPERANCE Esperance Communications 713344 GER.ALDTON Bird Electronics 641631 KAL.GOORLIE Todays Electronics ■ 212777 KARRATHA Daves Oscitronic 854836 PORT HEADLAND Ivan Tomek Electronics 732531 WYALKATCHEM D & J Pease 811132 NT ALICE SPRINGS Ascom Electronics 521500 Farmer Electronics 522388 DARWIN Ventronics 480030 ACT CANBERRA Bennett Commercial Electronics 805359 VICTORIA C ITY All Electronic Components 6623506 SUBURBAN CHELTENHAM Talking Electronics 5842386 CROYDEN Truscott Electronics ■ 7233860 PRESTON Preston Electronics 4840191 COUNTRY BENDIGO KC Johnson ■ 411411 MORWELL Morwell Electronics· 346133 QUEENSLAND CITY Delsound P/ L 8396155 SUBURBAN CAPALABAKingsway Electronics 3902399 WOODRIDGE David Hall Electronics 8082777 COUNTRY BUNDABERG Bob Elkins -Electronics 721785 GLADSTONE Supertronics 724459 MACKAY Philtron i cs ■ 578855 ROCKHAMPTONAccess Electronics (East St.) 221058 TOOWOOMBA Hunts Electronics ■ 329677 TOWNSVILLE So lex ■ 7724466 MAROOCHYDOREMals Electronics 436119 SA CITY Force Electroni c ■ 2125505 SUBURBAN BRIGHTON Force Electronics ■ 3770512 CHRISTIES BEACH Force Electronics ■ 3823366 ENFIELD Force Electronics ■ 3496340 FINDON Force Electronics ■ 3471188 LONSDALE Force Electronics ■ 3260901 COUNTRY MT.GAMBIER South East Electronics 250034 WHYALLA Eyre Elect ro nics ■ 454764 TASMANIA HOBART George Harvey ■ 342233 LAUNCESTON George Harvey ■ 316533 NSW CITY David Reid Electronics ■ 2671385 CAAINGHAH Hicom Unitronics 5247878 COFFS HARBOUR . Coifs Habour Electronics 525684GOSFORD Tomorrows Electronics 247246 GRAFTON East Coast Electronic 431250 NEWCASTLE Novocastrian Elect.Supplies 621358 RAYMOND TEqRACE Alback Electronics 873419 WINDSOR M & E Electronics 775935 WOLLONGONG Newtek Electronics ■ 271620 Vimcom Electronics 284400 WAGGA WAGGA Phillips You'll get a buzz out of this one Many years ago, as a factory hand I learned the difference between field faults and production line faults. Faults in the field tended to he simpler; at least one knew that the set had once worked correctly. But production line faults - well, it was anybody's guess as to what could have happened. Although this column will reach my readers a good deal later, I am writing it in the month of March. More precisely, it is March 17 and that is very appropriate for, as all good Wearers of the Green will know, March 17 is St Patrick's Day. And why is that so appropriate? Because this story deals with one of St Patrick's countrymen; one we all know and love to hate. Yes, that's right - Murphy! This is not my first story about Murphy's antics of course; there have been plenty of those. But this was a particularly vicious attack by that worthy which created a very weird and potentially frustrating situation. It all started when a dealer colleague for whom I do warranty repairs asked me to stop by his showroom and check a new set. In greater detail, it was a National Panasonic model TC 2969 which seemed to have excessive hum in the sound channel. And, as an afterthought, he added, "It'll probably only take you a few minutes to fix". He was probably being a mite sarcastic, but the remark had more sting in it than either of us realised at the time. The TC 2969 is a large screen model (68cm) and features a stereo sound system with external speaker outlets. It has been on the market for about two years now; time enough for most of the inevitable bugs to have surfaced and been duly swatted. In fact, it has been remarkably free of such beasties, so it came as 50 SILICON CHIP something of a surprise when a new set, just out of the carton, exhibited such an obvious fault. Still, these things do happen. So it was that I duly faced up to the offending set in the showroom. My colleague switched it on and I flicked it through several channels, expecting an obvious fault. Truth to tell, I was not immediately aware of any problem and it was only when I paid particular attention to the sound that I detected the background hum. But while it was more than there should have been in a set of this quality, it was not at . \ ~ 7)1~ .,111,,, . r: o d o I -- W~'( ~ M~-1'1 STUFF UP A, VJ01<.\(~ anything like the level my colleague had implied when he first called me. When I raised this point, my colleague looked puzzled but was adamant that the hum was "much worse than that" when he first switched the set on. So that was puzzle number one; the fact that the fault seemed to be variable. Or was it? In a showroom situation, where ambient sound can vary considerably, subjective assessment might be suspect. But for now, I had to assume the worst. Puzzle number two was something I couldn't quite put my finger on but the nature of the offending sound was worrying me. Before I could think much more about that, my colleague introduced a third factor - a second set with the same fault. It had been sold to a customer, delivered in something of a hurry late one afternoon and on the basis of a quick check, had seemed OK. However, the customer soon complained of excessive hum level and this had subsequently been confirmed by my colleague. So not only did we have a strange (variable?) fault but we had it in two sets. And this changed the scene completely. Instead of a oneoff component fault, I was now thinking in terms of a design or production line fault. But why should such a fault rear its ugly head at this time, after nearly two years? Of more immediate concern was what to do about the customer's set. My colleague had left the set with him on the basis that I could fix it, as he put it, "in a couple of minutes". But there was no way I was going to tackle a fault like that out of the workshop, with the real possibility that I would need help from the National service department. So my colleague decided to simply replace the customer's set. And this was another surprise; he had a third set on hand which was totally free of the problem. Anyway, the sets were duly swapped and the customer's set was delivered to my workshop. Frame buzz In the meantime in fact, as soon as I left the shop - I realised what was nagging me about the hum. Although my colleague had said "hum" - and I had accepted the term - it wasn't hum in the strict audio sense. Hum in an audio amplifier can be caused by induction into improperly shielded leads or by earth loops, etc. This hum will be at 50Hz and sounds low pitched and reasonably pure. Alternatively, it can be due to faulty power supply filtering in which case it will be at 100Hz and sounds higher pitched and rather rough. But it came to me in a flash that this was neither. It was low pitched - 50Hz - but harsh. That meant only one thing; it was frame buzz. I mentally kicked myself for being puzzled but frame buzz was the last thing I had expected to encounter in this set - even as a fault. A quick check on the customer's set confirmed both the nature of the buzz and that it was quite bad. I fished out the manual as a first step and in the process, came across a number of modification sheets which the firm had issued. And I must give National full marks on this score; they do make every effort to keep their servicemen up to date on any problems or modifications as they occur (unlike some other companies, which practise the mushroom treatment). Anyway, one of these mod. sheets caught my eye. It didn't nominate this particular set but I recognised the two boards involved; the " E" board and the "B" board. Both are used in this set and both needed modification, although no reasons were given. The "E" board mod. involved the audio output IC and on the "B" board, the IC for the earlier stages. And part of the mod. involv- ed fitting extra "earth" leads between sections. In the light of my problem, all this seemed to make sense. There wasn't a lot involved and I had the whole job done in about 20 minutes. But it didn't work; the buzz level was exactly the same as before. I was back to square one - and the realisation that I needed help. I rang one of my contacts in the National service department, outlined the nature of the problem, and described the changes I had made. His response to this latter point was not what I had expected. In mock sarcasm he told me to go back and take another look at the mod. sheet, because the mods. were not intended for that model set. In greater detail, he explained that they were intended for an M14 chassis whereas mine was an M15 chassis. I was well aware of the number of my chassis and said so, going on to point out that there was no chassis identification on the mod. sheet. Initially, he wouldn't buy this, insisting that there was a message at the top of the page clearly stating that these mods. were intended for an M14 chassis only. I eventually convinced him that there was no such message on my sheet. How it had been omitted, and from how many sheets, remains a mystery. But it was strike one to Murphy. The upshot of all this was (1) that I should remove the mods. as they had nothing to do with the problem; and (2) that he was well aware of the frame buzz problem and knew how to correct it. The cure was simple but the story behind it was quite complex. If I cared to listen he would fill me in. Always anxious to know the reason why, I said, "Go ahead" . Supply circuitry Fig.1 is the relevant portion of the circuit showing, in particular, the network providing the voltage regulating function for the switchmode power supply. This starts at IC801 at the bottom centre of the diagram. As shown, this IC consists of a transistor, a zener diode, and three resistors. It is connected to the 113V rail (pin 1) and a proporJUNE 1990 51 IL.!!£.J T801 ~ p For 21rnch L807-"- ET549K512A TSC937 ~ For 26/29rnch EXCELDR35C ET849K511A R813 330K Jp - & C849 0.01 500V D806 0-01 TVBESIC SOOY ® D827 IIA649RL Jl18 C818 680P 2KV I 86 8V~ C814 LBIO ,.&. TSC925-4 EXCELSA35B 5V 'I' TBC937~ EXCELDR35C IW [Hy] , r 0 1.0 1 8 ::==================-,---:----, [..806 & R837 I 113V B5 r 62 ft, I 64 C815 330P2KV L803 ,"TSC925-4~ EXCELSA35B ER 20V \ +113V E C842 E 22P 0850 aRZC10DK621 25V -~- [!ill R35C 825 I 7~P I ONI.Y FOR R8I9 S.8K RB40 180K Jt V 0815 El/2 r- R823 }';II 2SD965 0 0825 IIA4240 ------- R835 0-33 0808 1-5 2W :Z.'f-V 0806 2S0965R i I = -------------- --------l & CA-2969 - ___ , I R82Q 270 IC801 ~- s1854LBM-2: - - - __ .J 0802 25C1685/0R5 2SC331\A/OR5 Fig.1: the power supply circuit for the National TC 2969 TV receiver. IC801 is at bottom centre, with the optocoupler, Q803 and Q806 to its left. The additional diode, drawn in, is at the top right corner, near D827. tion of this voltage is fed to the transistor's base. The zener diode in the emitter circuit provides a voltage reference against which the base voltage is compared. The collector of this transistor (pin 2) is connected to the 18V rail (right of the diagram, half way up) via D823, R828 and the LED in opto-coupler D826 (ON3105R). The transistor in the opto-coupler is coupled to Q803, which is coupled to Q806, which is coupled to Q807. And Q807 is the " regulator" or "switching" transistor in the switchmode power supply. (Its collector connects to the OUT pin of the 52 SILICON CHIP switchmode transformer, T801). In normal operation, the IC801 LED will assume a brightness level determined by the actual voltage on the 113V rail. If this rises above 113V, the LED brightness will rise and its associated transistor will draw more current. This will increase the current through Q803 and in turn, the current through Q806. And this will pull down the base of Q807 and thus bring the 113V rail (and others) back to the correct value. (This network is also controlled by Q802 which, in turn, is controlled by the remote control receiver to turn the set on or off. But this a secondary function and is dormant at all other times). Well, if you've digested all that, let's go back to that 18V rail. As well as supplying IC801, this rail goes off up the diagram to perform another function. That other function is to power the audio output chip. And, as already mentioned, this set features outlets for external speakers. So what happens if John Customer fouls up the connections and puts a short across the speaker terminals? Well, for starters it takes out the audio chip, which is bad enough, but there's worse to come. When the audio chip fails, it shorts and takes out safety resistor R827 which shuts down the 18V rail. And that's when the fun starts. Since the 18V rail is involved in controlling Q807, loss of this voltage causes Q807 to turn hard on, with drastic consequences. The resultant over-voltage can take out transistors and ICs left, right, and centre. In a couple of cases, sets had been returned to the National service department which required extensive work to salvage them. Not all sets so abused were as seriously affected as this but this is what can happen. (Yes, the set has protective devices and circuits designed to prevent such mayhem but it appears that they do not always work, or work fast enough}. Back to the buzz And what has all this to do with the frame buzz problem? In case readers imagine that I've wandered off along some irrelevant sidetrack, let me assure you that such is not the case. Be patient and all will be made clear. Because of the problem just of the diagram, above Q802} and the idea was to connect this to the junction of D823 and R828 via a diode. Normally, this would have no effect because the diode would be reverse biased. But if the 18V rail failed, the diode would then be forward biased and so the 14V rail would now feed the LED in the optocoupler. It was not intended to keep the set working but it would maintain the opto-coupler circuit sufficiently to prevent Q807 from running amok. The scheme worked very well and had the advantage of being simple to implement; just one inexpensive diode tacked into the circuit. TETIA TV TIP Pye T29 chassis Symptom : Almost no vertical scan. Picture' reduced to a 2. 5cm band across the centre of the screen . Circuit diagram gives no useful voltages but those measured appear to be reasonable . Cure: 0504 (BC638) faulty. The transistor checks OK both in and out of circuit but will not amplify signals applied to its base. TETIA TV Tip is supplied by the Tasmanian branch of The Electronic Technicians' Institute of Australia. Contact Jim Lawler, 16 Adina St, Geilston Bay, Tasmania 7015. Strike two outlined, someone hit on a clever circuit modification which would protect the rest of the circuit should the 18V rail be knocked out. I'm not sure whether this was instigated by the parent company in Japan or whether it was a local development but it was very simple. There is a 14V rail in the set (top Enter Murphy for strike two, in the form of a wiring hand who couldn't tell one end of a diode from the other and wired a number of sets with the diode reverse connected. And that was what created the frame buzz. The fault was not discovered until some sets had gone into the field and there was no easy TV TEST EQUIPMENT PCB POWER TRANSFO RMERS (AUSTRALIAN MADE) SHORTED TURNS TESTER Built in meter to check EHT transformers including split diode type , yokes and drive transformers. $78.00 + $3.00 p&p HI-VOLTAGE PROBE Built-in meter reads positive or negative 0-50kV. Can also be switched to check negative voltages. For checking EHT and Focus voltages as well as TVs and Microwaves. Hi-tension voltages. $89.00 + $5.00 p&p LOW-VOLT AGE PROBE Ideal tor checking microwave ovens and TVs. The ~ ranges are from Oto 5kV and from Oto 1 OkV. Double insulated for safety. $79.00 + $5.00 p&p D Proudly manufactured in Australia by HARBUCH ELECTRONIC S P J 90 George St. , HORNSBY, N.S.W. , 2077 Phone (02)476-5 854, Fax (02) 476-3231 td DEGAUSSING WAND Strong magnetic field , larger than usual coil with multicore centre. Double insulated for safety with momentary switch operation. 240VA/C 2.2 amps. As important as having a soldering iron! $75.00 + $10.00 p&p TUNER REPAIRS We repair most tuners on an exchange basis. From only $1 7 .00 + p&p Cheque, Money Order, Bankcard or MasterCard Y.V.TuNERs) 216 Canterbury Road, Revesby, NSW 2212 Phone (02) 77 4 1154 JUNE 1990 53 \\1~,l/ ,~ ~ ~\Ii~\ ~ ;? , A -=--•- [l, . ,:;? . iii)> ~ ~ -, ' way to identify them. Fortunately, there weren't many but of course, a couple had to land on yours truly's doorstep. Don't ask me to explain why the reversed diode did what it did. I was happy enough to confirm that this was the fault in these sets and to put things right. All of which carries a clear message; such modifications, without the benefit of printed board markings, are risky. Introduce something new to a production line hand and the original Murphy's Law prevails; if something can go wrong, it will go wrong. A nudder story And now, in lighter vein, here's a short story from my colleague J.L. in Tasmania. Remember the story in the March issue a bout a colleague who had to re-orient his thinking in order to service the local sausage machine? Well, this is along similar lines, only this time it is a transition from TV sets and video recorders to 54 SILICON CHIP the much more mundane subject of dairies, cows and the associated milking procedures. Here's how J.L. tells it. Most electronic servicemen are "townies" and spend their time repairing domestic or commercial equipment brought to them by other townies. It's not often that we need to put on gumboots and solve farmyard problems. This story is about one of those situations where you leave dropped tools just where they fall. I mean, ankle deep in ordure is no place to go fishing for a $2 screwdriver, is it? (Speak for yourself, J.L., I come from a long line of Scottish ancestry). Imagine, if you can, a modern dairy farm where all cows carry electronic identification tags and their milk is instantly analysed so that appropriate feed supplements can be delivered to the computer controlled manger. Imagine further an automated milking line where the farmer has only to attach the cups to begin the extraction process. After the udder is empty, the lack of milk triggers a removal process which releases the cups and pulls the assembly away so that the cow can back out of the stall, all without further attention by the farmer. And one last point before we get to the story proper. Cows don't let down their milk immediately. They need half a minute or so to settle down before the milk flows, so the cup removal system needs to be inhibited during this period. This is accomplished with a simple automatic timer. So now to our story. Strawberry's problem It's early one wet and windy morning. Strawberry enters her stall and contentedly munches hay while farmer Giles washes the udder and attaches the cups. He moves the lever to start the suction and the cup assembly falls off the udder and is pulled upwards by the retracting mechanism. Farmer Farmer Giles rang Arthur to ask him if he would have a look at the you-know-what milking machine. It would be next week before the manufacturer's serviceman could reach him and poor old Strawberry could explode before then! Arthur knew a little about milking machines but none of the details of this one. But he was prepared to try, so it was on with the gumboots and a screwdriver on a string around his neck. Float switch Giles doesn't get out of the way in time and is clobbered by all four cups in turn. He lets fly with some unparliamentary language (and we all know what that means, don't we), then tries again, with the same result. The cups are retracted with a fair amount of force, so farmer Giles is beginning to feel rather battered and in no mood to argue with the "blankety-blank" machinery. So poor old Strawberry doesn't get milked that morning. Cows are only contented in their own stall and won't co-operate if put in any other. Nor will they co-operate if milked out of turn, so Strawberry can't be brought back later and milked by hand. Enter Arthur, a qualified electronics technician. Arthur is also one of those people who are happiest with their hands in the soil. He has a small hobby farm within commuting distance of town and grows fruit and vegetables to help keep the family fed. The cup release mechanism is activated by a float switch in the collector bowl above each stall. When the milk runs out, the float drops and closes a switch which operates a valve to release the vacuum that holds the cups in place. At the same time, a catch is released so that a spring loaded cord can pull the cups off the udder and up to the parked position at about shoulder height. The inhibit function, at the beginning of the milking cycle, is initiated by a switch attached to the vacuum lever. After the lever is operated, a 555 timer begins a 60-second countdown, during which the release mechanism cannot function. Our gumbooted serviceman learned all this by studying one of the other properly functioning stalls. So it took him very little time to realise that the faulty stall was not producing the inhibit signal due to a l000µF capacitor on the circuit board with a broken pigtail. As simple as that! Arthur's reward So endeth the technical part of the story but the best is yet to come. Farmer Giles was delighted with the prompt and efficient service and insisted that Arthur submit his bill for the time he had spent on the job. In the meantime, would Arthur let him show his appreciation with a small gift? Which is how Arthur came to drive home with a bucket of fresh milk, a side of lamb neatly butchered and packed in a cardboard carton, and a promise of all the fresh cream his family could consume. And a week later there was a cheque for the cash part of the deal as well. Why don't I ever get customers like that? Dunno J.L., but everyone up here had a good laugh over that story. And it brought back memories. As a callow country youth, when times were tough, I once earned my bread and dripping milking cows - and not with the aid of any new £angled milking machines either; it was all very rough and ready. And I learned about cows; just how stubborn, contrary, and cantankerous they can be. Nothing in your story surprised me one little bit. Truly is it said, they are "cows" of animals. ~ Fitting a Fax Card to Your PC: ctd from page 21 least cost) to you. Letterheads, signatures, logos, etc can all be transmitted provided you have access to a scanner (although you could fax your signature, etc back to your PC) and Fax89 supports most popular graphics file formats. The fax card, however, cannot be a total replacement for the fax machine. If you don't j:i.ave access to a scanner, there's no way you can send brochures, promotional material or pages from a manual. If the bulk of your work is non PCbased, then the fax card is really not for you. Rather, the fax card should be seen as an adjunct to the fax machine. Perhaps the scenario will be for a cheap lower-featured fax machine to transmit faxes while the PC fax card receives all incoming faxes. Also, the very nature of a fax suggests round-the-clock access. Are you prepared to leave your PC running all day and all night? However, for the PC user who works from home or a small office and mostly communicates via PCbased documents, a fax card probably meets all the specifications while presenting a major cost saving over a normal fax machine. The price of our sample fax card, the Fax89, was $599 from Eskay Printernet, Suite 3, 124 Marsden Street, Parramatta, NSW 2124. Phone (02) 891 1282. ~ JUNE 1990 55 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. Antenna control in Holden cars The antenna delay unit described in the March 1990 issue of SILICON CHIP is one way of solving the problem of replacing automatic antennas in Holden Commodores. The same problem occurs in the Statesman but there is a way of substituting an aftermarket antenna and still retain full use of the UP & DOWN control buttons. In the original setup, the car's antenna control unit furnishes two + 12V control signals (UP & DOWN). This is because the original antenna motor uses two lots of stator coils wound in opposite directions. Thus, applying + 12V to UP raises the antenna and applying + 12V to DOWN causes the motor to run in vent damage by low hanging trees or in undercover car parks. And, in most cases, having the antenna at "roof height" is quite adequate for city driving. This circuit allows the aftermarket antenna to operate in exactly the same manner as the original. Refer first to Fig.1. This shows the arrangement inside the antenna unit that I purchased. S1 is the limit switch and the centre contact is moved by a lever connected to the motor via gearing. When a limit is reached (either full up or full down), the lever pushes the centre contact, breaking the circuit and stopping the motor. The other set of contacts are still made and thus allow the motor to operate in the other direction. Note that when the antenna is MOTOR MOVED BY LEVER Fig.1: the arrangement inside the antenna. When the antenna reaches a limit, S1 moves & breaks one set of contacts. the opposite direction and lower the antenna. By contrast, aftermarket antennas use one motor and rely on a relay to reverse the supply to make the motor run backwards. It's better if the antenna only goes to half height initially to pre- NEON 1 Gutsy 220V power supply There is a lot of 220V gear on the market in this country masquerading as 240V equipment. This includes some computer power supplies, many imported bench drills, and nearly all AC-powered computer fans. In most cases, it is desirable to reduce the operating voltage to 220V to ensure long life. By configuring a relatively small step-down transformer as an autotransformer, it is possible to make a surprisingly compact 220V AC power supply. The circuit diagram shows how a low-cost Altronics M2165 power transformer can be used to supply 214V to 240V AC at currents up to 3A. This will drive large 'AC motors up to 0.75HP. It is essential to choose a transformer with suitable secondary-to-core insulation. For low power applications, such as computer fans, a much smaller transformer can be used; eg, the type 2851, 12.6V, 150mA transformer will supply 225V AC for loads up to 40VA. Also shown in the circuit are two optional neon lamps. One simply indicates whether 220V power is available, the other flashes whenever the fuse is blown. Note: for safety, the 4. 7MO resistor should be the Philips VR37 high voltage type, as used in the SILICON CHIP Touch-Lamp Dimmer project. When this circuit was tested on an imported pedestal drill, with a 220V, 500W motor, the peak starting current was reduced from a whopping 2 7A to 56 SILICON CHIP 01 1N4007 F1 5A 220VAC TO MOTORS ETC. 3A OR 0.75HP MAXIMUM LOAD 240VAC INPUT M2165 60VA r-----EARTH Nu-----------ACTUAL MEASURED OUTPUT VOLTAGES IN PARANTHESES * PHILIPS VR37 CASE 18A, and the no-load running current was reduced from 2.5A to 1.7 A (ie, a 50% reduction in IZR winding losses). The motor noise was also dramatically reduced. Steve Payor, Kogarah Bay, NSW. ($20) 01 1N4002 01 1N4002 UP---1--N--+-......- - - -......- -FROM EXISTING ANTENNA CONTROL UNIT -, +12V FROM EXISTING ANTENNA CONTROL UNIT 02 1N4002 02 1N4002 CONTROL ANTENNA UNIT RL 1b CHASSIS .,. Fig.3: this circuit will suit antennas with an internal changeover relay and a control line. D1 & D2 are steering diodes as before while the external relay is simply used to connect or disconnect + 12V to the control line. Fig.2: how the antenna is wired into circuit. The relay switches the connections to the antenna when the DOWN button is pressed. between limits (ie not fully up or fully down), the contacts are made as shown in Fig.1. Fig.2 shows how the antenna is wired into circuit. Dl and D2 are steering diodes and also isolate the UP and DOWN lines from the existing control unit. When + 12V is applied to UP, D2 is reverse biased, RLl is off, and the antenna goes up. After a delay, the control unit removes the + 12V from UP and the antenna stops. The antenna can ~-------- +12V then be extended to full height using the UP switch on the dashboard. When + 12V is applied to DOWN, D2 is now forward biased and RLl operates. The connections to the motor are now reversed and so the antenna lowers until the limit switch operates and stops the antenna motor. No extra parts were required since the relay and diodes came with the antenna kit. To install it, just rewire the relay as shown in Fig.2, mount the diodes on the relay base, and hook up the control lines. I. Bennet, Thomastown, Vic. ($15) Editor's note: the above circuit could easily be adapted to suit the type of antenna used with the Antenna Delay Unit (ie, those with an internal changeover relay). Fig.3 shows the details. In this case, the changeover relay is simply used to connect or disconnect + 12V to the control line. 10k 1 INPUT 47_k 22k 22k -:- ":' 4.7 10k 40W bridged power amplifier If you need a high power audio amplifier in a real hurry, take a look at this circuit. It is based on the LM1875T 20W Audio Power Amplifier from National Semiconductor. The input signal is AC coupled via a lJ,tF capacitor and then buffered by IC la and inverted by ICl b. This produces two out-of-phase signals at pins 1 & 7 and these drive the two LM1875Ts which are con- nected in a non-inverting bridge mode. Because the two power amplifiers are driven in anti-phase, the output voltage is doubled and this theoretically gives four times the power output of a single device. In practice, the devices cannot handle four times the usual output power and we only achieve double the original power. Each power amp has a gain of 27dB, giving an overall gain of 33dB in bridge mode. The 100 resistor and O.lJ,tF capacitor across the speaker form a Zobel network and this prevent s high frequency oscillation. Note that the LM1875Ts should be bolted to large finned heatsinks. Darren Yates,. French's Forest, NSW. ($20) Note: proper layout of the PCB is necessary to ensure amplifier stability. Readers are referred to the application hints for this device in the National Semiconductor Linear Databook, Vol.3. A PCB pattern is shown in the handbook and should be closely followed. JUNE 1990 57 End of financial year BOARD SOLUTIONS BOARD SOLUTIONS Pty Ltd INTERNAL FLOPPY DISK DRIVES I MOTHERBOARDS 10MHz XT, (640K) OK RAM 10MHz XT, (1 MB) OK RAM 33MHz XT286 OK RAM Baby 286, 20MHz/0K RAM 286, all-in-one, OK RAM Baby 286, 12MHz VLSI OK RAM 12MHz NEAT 286 OK RAM 20MHz 286 OK RAM 16MHz 386SX, OK RAM 25MHz 386, 32K Cache, OK 33MHz 386, 32K Cache, OK I M1010 M1000 M1020 M2000 M2010 M2020 M2040 M2045 M3000 M3010 M3020 99.00 129.00 199.00 695.00 545.00 449.00 499.00 845.00 895.00 2495.00 2795.00 Z9300 Z9380 Z9400 Z9480 Z9500 Z9200 29.95 32.95 8.95 9.75 275.00 32.95 Z9212 Z9112 Z9000 Z9010 Z9020 29210 Z9540 Z9210 Z9550 Z9555 Z9560 Z9565 Z9570 Z9575 Z9580 Z9585 Z9680 12.00 4.95 24.95 39.95 49.95 5.45 795.00 5.45 449.00 495.00 549.00 649.00 649.00 749.00 949.00 1099.00 295.00 CHIPS 1M RAM Chip - 1OOnS 1M RAM Chip - sons 256K RAM Chip - 1OOnS 256K RAM Chip - sons 8087-2, 8MHz Co-Processor 4 X 256K RAM Chip, 1OOnS 4 X 64K RAM Chip, 120nS For VGA card 64K RAM Chip - 120nS NEC V20 Chip NEC V20 Chip, 10MHz NEC V30 Chip, 10MHz 64K RAM Chip - 1OOnS 80387SX 16MHz Co-Processor 64K 1OOns RAM Chip 2C87-8MHz (equiv 80287/8) 2C87-10MHz (equiv 80287/10) 2C87-12MHz (equiv 80287/12) 2C87-20MHz 3C87-16MHz (equiv 80387/16) 3C87-20MHz (equiv 80387/20 ) 3C87-25MHz (equiv 80387/25) 3C87-33MHz (equiv 80387/33) SIMM Module, 1MB sons YE-Data 360K YE-Data, 720K/1.44M D3000 drive Plus Frame YE-Data, 1.2MB I D5500 D3000 D3010 D5510 145.00 175.00 199.00 175.00 INTERNAL HARD DISK DRIVES NEC 42MB, 28mS 3.5in D8000 plus Frame M'scribe 40MB AT BUS NEC 3.5in 134MB 23mS ESDI NEC 3.5in 134MB 23mS SCSI NEC 5.25in 179MB 18mS ESDI NEC 5.25in 380MB 18mS ESDI NEC 5.25in 760MB 16mS ESDI NEC 5.25in 380MB 18mS SCSI NEC 5.25in 760MB 16mS SCSI Kalok 20MB 40mS Seagate 20MB ?Oms RLL inc XT controller. Seagate 20MB 65ms RLL inc XT controller Seagate 30MB 65ms MFM inc XT controller Seagate 40MB ?Oms MFM inc XT contro ller Seagate 5.25in 40MB 40ms ALL Seagate 5.25in 40MB 28ms RLL Seagate 5.25in 65MB 40ms ALL Seagate 5.25in 65MB 28ms RLL Seagate 20MB 5.25in40ms MFM Seagate 20MB 5.25in28ms MFM Seagate 30MB 5.25in40ms MFM Seagate 30MB 5.25in28ms MFM Seagate 30MB 3.5in 40ms RLL Seagate 30MB 3.5in28ms ALL Seagate 49MB 3.5in40ms ALL Seagate 49MB 28ms RLL Seagate 42MB 24ms V/C I D8000 D8010 D8020 D8030 D8040 D8050 D8060 D8070 D8080 D8090 D8100 745.00 775.00 795.00 1595.00 1795.00 1995.00 3995.00 5995.00 4195.00 6195.00 399.00 D8200 499.00 D8210 529.00 D8220 579.00 D8230 D8240 D8250 D8260 D8270 D8300 D8310 D8320 D8330 D8350 D8360 D8370 D8380 D8390 625.00 649.00 699.00 739.00 799.00 429.00 479.00 599.00 649.00 549.00 599.00 649.00 699.00 749.00 I EXTERNAL FLOPPY DISK DRIVES For Amiga 500 , 1000, 2000, 3:5in 880K For Amiga 500, 1000, 2000, 5.25in 360/BBOK For Commodore PC1 , 5.25in 360/720K 40/80 track For Atari ST series, 3.5in 720K For Atari ST series, 5.25in 360/720K 40/80 track For Amstrad PC1512/1640, 3.5in 720K For IBM XT, 3.5in 720K XT For IBM AT, 3.5in 1.44MB For IBM XT, 5.25in 360K For IBM AT , 5.25in 1.2MB For TOSHIBA laptop series, 5.25in 360K For TOSHIBA laptop series, 5.25in 1.2MB D9500 249.00 D9510 299.00 D9520 D9530 299.00 299.00 D9540 299.00 D9550 D9560 D9570 D9580 D9590 269.00 299.00 329.00 299.00 329.00 D9600 349.00 D9610 399.00 MICE & JOYSTICKS Joystick Logitech Mouse, 2 button serial Logitech Mouse, 2 button serial + Paint S/W Logitech Bus Mouse, 2 button + Paint S/W Mouse Mat J1000 J1010 49.95 149.95 J1020 149.95 J1030 J1040 149.95 7.50 MONITORS Monitor, 14in TTL, Amber Monitor, 14in TTL, Green Monitor, 14in TTL, Paper White Monitor, 14in EGA Monitor, 14in VGA Monitor, 14in Multisync Monitor, NEC 14in Multisync 3D M4000 M4010 M4020 M4030 M4040 M4050 M4060 249.00 249.00 249.00 599.00 749.00 899.00 1275.00 PHONE OR FAX NOW FOR LATEST PRODUCTS. PRICES AND INFORMATION OUR MATHS CO-PROCESSORS UP TO 300% FASTER THAN INTEL! The experts say that, after memory and a hard disk, a math co-processor is one of the best upgrades you can make . "If you are a number or graphics cruncher, your first upgrade should be an Intel 8087, 802787 or 80387 maths co-processor. (PC World, February 21) We only partly agree! Sure, it shoud be a maths coprocessor - but our new co-pro's are significantly faster than Intel's - up to an amazing 300% faster! Type: Equiv: Cat No: 2C87-8 80287/8 Z9550 2C87-10 80287/ 10 Z9555 2C87-12 80287/12 Z9560 2C87-20 Z9565 Price: 449.00 495.00 549.00 649.00 Type: 3C87-16 3C87-20 3C87-25 3C87-33 Equiv: Cat No: 80387/ 16 Z9570 80387/20 Z9575 80387/25 Z9580 80387/33 Z9585 Price: 649.00 749.00 949.00 1099.00 • .budget: Use it pr Lose it? HAS THE STOCK· RIGHT NOW! . . II MICRO CHANNEL Dual Sync Adaptor, PS/2 2MB RAM Card, PS/2 OK RAM 8MB RAM Card, PS/2 OK RAM I I 11080 11100 11090 11041 11000 99.00 65.00 34.95 29.95 129.00 11010 11020 11030 11040 11050 11060 11070 11080 11090 149.00 29.95 55.00 79.00 99.00 55.00 75.00 99.00 245.00 V1000 V1010 V1020 V1030 V1035 349.00 449.00 129.00 249.00 179.00 V1040 99.00 POWER SUPPLIES 200 Watt PSU Suit Tower Case 200 Watt PSU Suit Baby T Case 150W PSU , Circuit Board 150W Switching PSU - XT 200W Switch PSU - Baby AT 200W PSU , Baby AT, L Type 220W Switching PSU -AT 200W PSU With Battery Backup 150W PSU Cap. 220nF/200V P2020 P2030 P1500 P1510 P2000 P2010 P2200 P2300 P9000 175.00 149.00 85.00 124.00 149.00 149.00 195.00 695.00 3.95 Microtronics Micro Electronics Hobbies And Electronics Nth. Qld. Adv. Technology Newtronics Coifs Harbour Electronics Al Electronics John Sommerlad Electronics Beta Electronics lnverell Computer Bits ACR Computers Leeton Audiotronics Cycle & Sound Decro Electronics Steven's Electronics Keller Electronics Morwell Electronics Hutchesson's Communic. Outback Electronics Headware Nambour Electronics Namoi Computers Bassham 's TV & Computer Brad 's Electronics Super Solex Ph1llip's Electronics Windsor Communications 95.00 115.00 199.00 II RAM CARDS RAM Card, OK RAM , XT only 2MB RAM Cd, OK LIM/ EEMS AT 2MB RAM Cd, OK LIM/EEMS XT 6MB RAM Card, -OK RAM 4MB Fast Card Suit 20MHz +SX 32 Bit RAM Card 25 + 33MHz Floppy Disk Card, 4 Ports 360K Disk Cont 4 port, 2In 2Ex or 4In Floppy Disk Card All Drives ESDI Hard Disk Cont Card - AT ESDI HDD/ FDD Card - AT Hard Disk Cont, 1 :1 lnt. AT HDD/ FDD Cont, 1:1 lnt. AT Hard Disk Cont,1 :1 lnt. RLL, AT HDD/FDD Cont, 1 :1 int, RLL, AT SCSI Card for AT SCSI HDD/ FDD for AT Hard Disk Controller, XT Hard Disk Controller, RLL-XT R1000 R1010 R1020 R1030 R1040 R1050 99.00 265.00 245.00 295.00 299.00 349.00 Hinged, Baby AT Full Size Hinged AT Case Hinged Baby AT w/200W PSU Slimline 'XT' or 'AT' with PSU 3.5in Hard Disk Ext. + Cable 5.25in Floppy Disk Ext. + Cable 5.25in Full Height Ext. + Cable 5.25in Mount for 3.5in Drive Baby Tower Case AT Baby Tower Case + 200W PSU Tower for 6 Dev., Swit. at Top Tower for 6 Dev. & 200W PSU 2121799 412 077 884 908 466 898 439 600 525 684 248 322 323 661 348 232 223 769 281 6155 532 081 290 579 214137 511 723 214 559 346133 250400 433 475 723 895 411 604 923 274 822 788 526 603 724 466 216 558 775 935 NEW DEALERS REQUIRED IN BRISBANE, DARWIN, MELBOURNE AND HOBART. PLEASE CALL ! I E1000 E1030 E1010 E1040 E1050 E1060 E1070 E1080 E1090 E1100 E1105 E1110 E1120 55.00 130.00 99.00 349.00 399.00 225.00 249.00 249.00 275.00 249.00 275.00 125.00 145.00 C1000 C1005 C1010 C1020 C1030 C1040 C1050 C1060 C1070 C1080 C1090 C1110 125.00 175.00 249.00 275.00 99.00 115.00 125.00 25.00 160.00 299.00 299.00 449.00 • 14 Day money-back guarantee (except software) • At least 6 months warranty on all our products. • Mail orders are our speciality! • Road Freight on normal size items is $9.00 • Insurance $1.00 per $100 of order value • All prices INCLUDE sales tax • We accept Visa, Bankcard, Mastercard and Post Office COD • Call for latest price list • Special prices apply until June 30, 1990 - or while stocks last! • Leasing facilities available: just ask! • Government pricing available on request C1120 299.00 C1130 C1140 499.00 95.00 I INTERFACE CARDS 48 Line 1/0 Card F1000 Serial RS-422 Adaptor F1010 Industrial 1/0 Card F1020 Universal Wire-wrap Card F1030 Dual Serial RS-422 Card F1040 80286 Speed-up Card F1050 IEEE 488 Interface Card F1060 IEEE 488 Interface Card- National Compatible F1070 A-D/D-A Converter, 12 bit, 1 Ch. F1080 A-DID-A Converter, 12 bit, 2 Ch. F1090 Clock Card · XT F1100 EPROM Writer Card F1110 Games Card- 'XT'& 'AT' F1120 110.00 135.00 445.00 125.00 195.00 495.00 299.00 549.00 199.00 449.00 50.00 245.00 35.00 I NETWORK I CASES MAJOR AUTHORISED DEALERS Adelaide Albany Broken Hill Cannonvale Charlestown Coifs Harbour Devenport Glen Innes Hobart lnverell Ipswich Leeton Lightning Ridge Lismore Mackay Maryborough Morwell Mount Gambier Mt Isa Mudgee Nambour Narrabri Port Lincoln Taree Townsville Wagga Wagga Wincfsor K1000 K1010 K1020 DISK CONTROLLER CARDS I VIDEO CARDS VGA Card, 800 x 600 VGA Card, 1024 x 768 Magic Combo CGA Card EGA Card, with Hercules Mode **NEW** EGA Card Mono Hercules Card, 16MHz operation + Parallel Port 84 Key Keyboard XT/AT 101 Key Keyboard, XT/AT 101 Key Keyboard+ TrackBall II 1/0 CARDS 2 Ser. 1 Parallel AT board 1 Ser. 2 Parallel XT/AT board Chip Set (16450) Chip Set & Cable suit 11040 Multi 1/0 Card XT only Multi 1/0 Card, 2 Ports all 4 drive types supported Parallel Printer Card Serial PortCard X 1 Serial PortCard X 2 1/0 Plus Card - XT Only Serial/Parallel Card - XT/AT 2 Serial , 2 Parallel, AT Games , Par, Serial XT/AT Multi-Serial Card , 4P-AT I MC1000 349.00 MC1010 349.00 MC1020 599.00 Tower for 6 Devices, Switches in Middle Tower for 6 Devices, + 200W PSU , Switches in middle Case, hinged XT KEYBOARDS SK Ethernet 8 bit with T Adaptor 16K Ethernet 16 bit with T Adaptor Ethernet 50 Ohm Terminator Thin Ethernet Cable , 25 feet Thin Ethernet Cable , 50 feet Thin Ethernet Cable , 75 feet Auto Boot ROM for NEE1 Auto Boot ROM for NEE2 Workstation , 12MHz Diskless, with 1MB RAM N1000 399.00 N1010 N1020 N1030 N1040 N1050 N1060 N1070 449.00 12.75 35.00 49.00 62.00 35.00 35.00 N2000 2495.00 CABLES I OH NO! We've run out of room to show you our great range of cables , connectors and gender benders. For details of any of these products, call Board Solutions today. No obligation , of course! BOARD SOLUTIONS IS YOUR ONE-STOP PC ENHANCEMENT COMPANY fJ~ Sffeit4 4, BOARD SOLUTIONS - . PO BOX 1120, LANE COVE NSW 2066 TEL (02) 906 5696 FAX (02) 906 4592 Avoid traffic fines: fit this speed alarm Fit this speed alarm to your car and avoid the possibility of heavy fines and possibly even losing your driver's licence. It will give you a brief audible warning each time you exceed a pre set speed so you can ease off the pressure on the accelerator. Design by PETER GRAY Every licenced driver exceeds the speed limit at some time or other but, depending on which state you live in, there could be a heavy financial cost for doing so. It is bad . enough when you knowingly exexceed the speed limit, because at least you know you are taking a risk. It is when you unknowingly exceed the speed limit that you could be in real trouble. 60 SILICON CHIP Maybe the stress of the journey has caused you to press down imperceptibly harder on the accelerator or maybe a long downhill slope has let the speed build up. This can happen easily if the vehicle you are travelling in is new and particularly quiet. In these circumstances you need an overspeed alarm to bring you back to reality. This kit is designed to monitor vehicle speed and give an audible warning if one of three preset speeds are exceeded. The circuit has the following features: (1). It monitors three user settable speeds; eg, 60, 80 & 100km/h. (2). Once installed and set the unit requires no further adjustment by the driver. You don't want to be fiddling with knobs every time you enter a different speed zone. (3). )'he unit can give an audible or visible warning. (4). As each preset speed is reached, the buzzer sounds briefly. If you drive within 1 to 2km/h of the preset speed, the buzzer sounds continuously. If you ignore the warning and accelerate, the unit will not sound again, until you reach the next preset speed. (5). The device can be fitted to any car - front or rear wheel drive. (6). The circuit uses a Hall Effect sensor to monitor true vehicle speed, not engine RPM. Therefore you don't get false warnings caused by high revs in low gears. The kit is essentially just a small printed circuit board with external connections to the car's 12V supply, to a buzzer and to the speed sensor. It can be mounted in a convenient spot underneath the dash. How it works As noted above, the circuit (Fig.1) uses a Hall Effect device and this senses magnets which need to be fitted to the tailshaft or transaxle. If the vehicle has a tailshaft, four magnets are required while for cars with a transaxle (all front wheel drives and VW s ), one half shaft is fitted with two magnets. The Hall Effect sensor is mounted close to the tailshaft (or half shaft) and each time a magnet passes, the sensor pulls its "open collector" output low. Essentially, the Hall Effect sensor generates a train of pulses which are directly proportional to the speed of the vehicle. These pulses are fed to pin 1 of IC1, an LM2917N frequency to voltage converter. This gives a DC voltage output at pin 5 which is directly proportional The speed of the vehicle is monitored by a Hall Effect device which senses magnets fitted to the tailshaft or transaxle. Each time a magnet passes, the sensor pulls its open collector output low. to the repetition rate (ie, frequency) of the pulses at its input. The component values at pins 2 and 3 of the LM2917 give a linear DC voltage at pin 5 for a range of input frequencies from zero up to about 80Hz. This should be sufficient for most vehicles for speeds up to 120km/h. The varying DC output of IC1 is fed to the non-inverting ( + ) inputs of the three comparators in ICZ, an LM339 quad comparator IC. Each of these three comparators, ICZa, Zb and 2c, has its inverting input connected to the wiper of a 1Ok!J trimpot, VRl , VRZ and VR3 respectively. These trimpots provide the three adjustable speed settings. Each of the three comparator outputs is connected to the gate of a silicon controlled rectifier (SCR) via a 10k!J resistor and .OlµF capacitor. If the DC output voltage from ICl exceeds the preset voltage at pin 4 of ICZa, pin 2 will switch high 470 Q 4.7k 10k +9V .,. 10 ,. IC1 LM2917N ,. + 11 + 9V D1 1N914 1M 470k A + .,. OI .,. 100k 1J .,. .,. 1M 1M SCR3 C203B 100 1W OUT +12V FROM IGNITION 2D1 16V j GND+ lW + .,. 01! .,. .,. +9V 10k 100! A .,. B .,. VR3 10k .,. AGDK ,~oo, EIO C VIEWED FROM BELOW GN0 OVERSPEED ALARM Fig.1: the Hall Effect sensor pulses frequency to voltage converter ICl. This produces a DC voltage at pin 5 which is monitored by comparators IC2a-IC2b. When a comparator output switches high, its corresponding SCR briefly turns on and turns on Qt & the buzzer via Schmitt trigger IC2d. JUNE 1990 61 I :::Jll'llS!r.l: IWsm: +12V FROMIIGNITION 1O11 1 W ZD1 CHASSIS SENSOR EARTH __:,....,...a.)_ ---BUZZER + +9V TO SENSOR-'..-4-4;.ilsiii~,_,;;;-,l".J:~ ~ ~ ~I,...!.-... BUZZER - Fig.2: take care to ensure that all polarised parts are correctly oriented when assembling the PC board. These parts include the electrolytic capacitors, the SCRs, Qt and the ICs. PC stakes are used to terminate the external wiring connections. 0 RESISTORS No □ □ □ □ □ □ □ □ □ 3 1 1 6 1 4 1 1 1 Value 1MO 470k0 100k0 10k0 4.7k0 3.3k0 6800 4700 100 and a brief positive pulse will be delivered to the gate of SCRl via the RC components just mentioned. This will cause SCRl to conduct and discharge the lµF capacitor at pin 10 of IC2d, the fourth comparator in the package. Discharging the lµF capacitor causes pin 10 of IC2d to be pulled low so that pin 13 goes high and turns on transistor Q 1 via the 1OkO resistor. This sounds the buzzer. Once the lµF capacitor has discharged, there is not enough current flowing through SCRl to keep it turned on and so it turns off. This allows the lµF capacitor to charge up again via the associated 470k0 resistor. This pulls pin 10 of IC2d high and so Q 1 turns off and so does the buzzer. :, 0.. .... ., + lr""' I' w AREA FRONT VIEW MOUNTING BRACKET TO BODY D D D TOP VIEW 62 SILICON CHIP 4-Band Code (5%) brown black green gold yellow violet yellow gold brown black yellow gold brown black orange gold yellow violet red gold orange orange red gold blue grey brown gold yellow violet brown gold brown black black gold 5-Band Code (111/o) brown black black yellow brown yellow violet black orange brown brown black black orange brown brown black black red brown yellow violet black brown brown orange orange black brown brown blue grey black black brown yellow violet black black brown brown black black gold brown So the net effect of exceeding one of the preset limits for IC2a, 2b or 2c is to turn on one of the three associated SCRs briefly and so sound the buzzer briefly. Furthermore, each comparator and SCR combination needs to be reset before it can sound another warning. To explain this, let's consider IC2a and SCRl. If the speed limit set by VRl is exceeded, the output at pin 2 of IC2a will go high and trigger SCRl as explained before. SCRl then cannot turn on again until it receives another gate trigger pulse via the :01µF capacitor and lOkO resistor. For this to happen, the output of IC2a must first go low, to discharge the .OlµF gate capacitor. For that to Fig.3: the Hall Effect sensor is installed on a mounting bracket attached to the car body, while the magnets are epoxied to the tailshaft [or transaxle). Note that the magnets must pass within 3mm of the sense area of the Hall sensor. The sensor is also pole sensitive so be sure to install the magnets the right way around (see text). happen, the vehicle must drop below the limit set by VRl. If you drive at close to the preset speed for IC2a, its output will randomly flick high and low so that SCRl is being retriggered all the time. This will sound the buzzer continuously. The same comment applies for the other two comparators and their SCRs. Power for the circuit is derived from the vehicle's + 12V supply via the ignition switch. The + 12V is fed to a 7809 9V 3-terminal regulator which then supplies the rest of the circuit. Protection against excessive input voltage or spikes is provided by the 100 resistor and associated 16V 1W zener diode at the input of the 7809 regulator. A feature of the circuit is that every time the ignition switch is turned on, the buzzer will sound briefly, to let you know the speed alarm is working. Board construction The PC board measures 105 x 43mm and accommodates all the components except for the small buzzer. The component layout is shown in Fig.2. We suggest you first check the board carefully for any faults such as hairline cracks in the tracks, The completed PC board and the buzzer can be housed in a plastic zippy case and hidden under the dashboard. We used sockets for the two ICs but suggest that you solder them straight in for improved reliability. Use PC stakes to terminate the external wiring connections and note that the prototype used on resistors instead of the wire links shown in Fig.3. shorts between tracks or undrilled component holes. These should be corrected before any components are installed. Begin the assembly by installing all the resistors and soldering them in. Check the value of each resistor with your multimeter before it is put into the board. You can then install the capacitors, making sure that the electrolytics are inserted the right way around. Next, fit the diode Dl and the 16V zener, ZDl. After those, fit the three SCRs, Ql and the 3-terminal r egulators. Finally, fit the three multiturn trimpots and the two ICs. Testing To test the board, you ideally need a function generator or an oscillator which can put out square waves of at least 2 volts peak-topeak or a sinewave output of larger amplitude. You also need a power supply which can deliver 12 volts DC. This will enable you to test the board on the bench before it is fitted to the car. Connect the buzzer and the 1 ZV power supply to the board, then use your multimeter to check for the + 9V rail at the output of the 3-terminal regulator, at pins 8 and and 9 of ICl, and at pin 3 of ICZ. Set trimpot VRl so that pin 4 of ICZ is at, say, + 3V; set VRZ so that pin 8 of ICZ is at, say, + 4V and set VR3 so that pin 6 of ICZ is + 5V. Now start with the oscillator set to the lowest possible frequency and increase it slowly while monitoring the output of ICZa at pin 2. It should start low and then switch high suddenly when the voltage at pin 5 exceeds that at pin 4. When this happens, SCRl should conduct briefly and pin 13 of ICZd should go high to turn on Ql and the buzzer, for a brief time. As you turn up the oscillator frequency, the buzzer should sound again, corresponding to the output of ICZb, pin 14, going high and turning on SCRZ. Finally, the buzzer should sound a third time, corresponding to the output of ICZc, pin 1, going high and turning on SCR3. Now reduce the oscillator output frequency to the minimum and confirm that the buzzer again sounds three times, as the frequency is increased. If you monitor pin 5 of ICl you will find that the voltage rises as the input frequency is increased. A point will be reached where the voltage does not change any more as frequency increases. On the prototype, this was at about + 6V and an input frequency close to 80Hz. Installation The Hall Effect sensor in this pro- Where to buy the kit The Speed Alarm was designed by Peter Gray of Novocastrian Electronic Supplies Pty Ltd. The full kit of parts including printed board , Hall Effect sensor and magnets will be available from Novocastrian Electronic Supplies Pty Ltd, as this issue goes on sale . The full price of the kit is $49 .95 plus $3 post and packing to anywhere in Australia. The Hall Effect sensor will be available separately as Part No. KOSASENS for $14 .95, while the magnets will also be available at $1 . 56. All prices include sales tax. Contact Novocastrian Electronic Supplies Pty Ltd , 24 Broadmeadow Road, Broadmeadow, NSW 2292 ; or PO Box 87, Broadmeadow 2292 . Phone (049) 62 1358. JU NE 1990 63 PARTS LIST 1 printed circuit board, code PGOSA10/89, 105 x 43mm (copyright Novocastrian Electronics) 1 piezo buzzer 6 PC pins 4 magnets (only 2 required for transaxles) 3 1 0k0 multiturn trimpots (VR1, VR2, VR3) Semiconductors The 7809 3-terminal regulator is installed with its metal tab towards the O.lµF capacitor. The multi-turn pots are used to set the three alarm speeds, as described in the text. ject is a custom job. It is encapsulated in epoxy and has three terminals for + , - and output. Since all cars are different it is left to the constructor to decide where to mount the sensor but the following points should be noted before installation begins. (1). Hall Effect sensors do not have a high sense distance, typically 2-3mm. This unit is no different. When choosing a mounting point for the sensor ensure that it will not obstruct any other part of the car. (2). When choosing a mounting site, remember that you have to be able to mount a bracket for the Hall Effect sensor that will allow it to sit within 2-3mm of the magnet faces. You will need to make a mounting bracket, as shown in Fig.3. (3). The magnets need to be epoxied in place on the tailshaft or transaxle halfshaft, so follow the instructions carefully for the glue you use. We don't recommend 5-minute epoxy for this job - use a stronger variety which takes longer to set. Give it at least 24 hours to cure properly. (4). The Hall Effect sensor is pole sensitive so the magnets must be mounted with their poles facing the right way. If you don't do this correctly, the Hall Effect sensor won't work. Magnets supplied in the kit (from Novocastrian Electronic Supplies) will have their pole faces marked. Also don't be a wally and work 64 STLTCON CHTP under a car supported by a jack only. This is a car ramp and wheel chock job only! (5). Read 1, 2, 3 and 4 again. The Hall Effect sensor is the heart of this project. If it is not installed properly the rest is a waste of time. (6). The printed board and buzzer can be mounted in a zippy box and hidden under the dash. The buzzer is fairly loud so it need not be mounted separately. Until tested, leave the wiring and board accessible. (7). To give a visible warning, you could wire a LED and 4700 resistor in series across the piezo buzzer. Most people will probably find the buzzer is all they need. Vehicle testing When connections have been made from the sensor to the board and the piezo buzzer and supply connections have been made, you are ready for a test. Get someone else to drive the vehicle while you monitor the DC voltage on pin 5/10 of the LM2917. As the car moves you should see a DC voltage appear and increase as vehicle speed increases. If you don't, chances are the Hall Effect sensor is too far from the magnet face or you've installed the magnets back to front (very bad!). If all goes well, get your mate to drive the car (in the correct speed zone) at the speeds you wish to monitor. Set the trimpots so that the 1 Hall Effect sensor (see text) 1 LM2917 F/V converter (14-pin version, IC1) 1 LM339, GL339 quad comparator (IC2) 1 7809 9V 3-terminal regulator 1 BC547 NPN transistor (01) 3 C2038 200V SCRs (SCR1 ,2,3) 1 16V 1 W zener diode (ZD1) 1 1 N914 silicon diode (D1) Capacitors 1 2 1 3 1 00µF 16VW PC ele ctrolytic 1µ,F 1 6VW PC electrolytic 0. 1 µF metallised polyester .01 µF metallised polyester Resistors (0 .25W, 5%) 3 1 1 6 1 1MO 4 70k0 1 00k0 1 0k0 4.7k0 4 1 1 1 3.3k0 6800 4700 1 on 1 W Optional 1 red light emitting diode 1 4700 0.25W resistor 1 plastic utility box Miscellanous Epoxy adhesive, hookup wire, solder buzzer sounds as you exceed the selected speeds by, say, 5km/h. Some fine tuning may be required. With this done you should be rewarded with a beep each time you exceed any of the preset speeds. If you hover around any preset speed, the buzzer will sound more or less continuously, urging you to slow down. This is because the output of the relevant comparator (IC2a, 2b or 2c) is flicking up and down and retriggering its SCR. The buzzer should not sound when you decrease speed. I§;] UPER AVINGS AT HERIDAN 'S BLACKTOWN (02) 621 1494 SHOP 30, PATRICK STREET, CENTRAL PLAZA CAPACITORS only $4.50 ea COMPUTER/VIDEO JOYSTICK * DUAL FIRE BUTTONS * RAPID FIRE BUTTON * SUCTION FEET 1 O,OOOµf 40 VOLT 22,000µf 25 VOLT FOR ATARI OR COMMODORE COMPUTERS STATIC RAMS 2114 $1.00ea 4116 $1.70 6 11 6-1 $4.50 6264 $6.00ea 62256 -80 $19.95 only $15.00 DRAMS 41 64-1 5 $2.00ea 41256-12 $6.00ea 41464-1 $7.00ea SCOOP BUY $1.95 ea BENCH STYLE AUTO RANGING DIGITAL METER (Reviewed May 90SC) GENUINE TELECOM DOUBLE ADAPTOR ONLY WHILE STOCK LASTS OW LIMITED QUANTITY AT THIS PRICE Volt 1 0 Amp Relay Volt 6 Amp Relay Volt 6 Amp Relay Volt 1 5 Amp Relay Volt 2 Amp Miniature Relay 599 ■ 95 COMPUTER DISKS 3½ DSDD $15.00/10 5¼ DSDD $8.50/10 e~ 12 12 5 48 12 N SAVE $ 3 0 .00 $2.95 $2 .00 $1.50 $1.00 $1.50 3.5" & 5.25 " DISC DRIVE CLEANERS $5.5 0 ea 1111 I 0 ONE TOUCH PLAYBACK ANSWERING * VOX RECORDING $ 139.95 TWO SPEED CORDLESS DRILL & SCREWDRIVER * USE UP TO 1 5 TIMES * NON ABRASIVE DISC *CONTAINS SAFE CLEANING FLUID MAIL ORDERS TO: SHOP 30, PATRICK STREET CENTRAL PLAZA, BLACKTOWN NSW 2148 NEXT TO HOUSING COMMISSION PLENTY OF PARKING AND CLOSE TO RAILWAY STATION Mail Charges: $15-$19.95 ..... . . . $20-$39.95 . .. . ... . $40-$69 . . .... . . . . $70-$99 , ,,, , ... . . b ~ Trading Hou rs: Mon•Wed, Fri .. . ... 9am-5.30pm . . .. . $5 Thurs . . . . . . . . . . . . 9am-8pm VISA ... . . $7 Sat . . .. 9am-3pm . .. . . $8 ... $10 ~ -- - - - - . . . . __ __ _ _ __ NOTE: We accept Ban kcard, Mastercard and Visa. Ho wever, we cannot give quantity $100 and over . ... . . . . . $15 Large or overweight articles sent Skyroad Freight Forward. discounts on credit card purchasers or account orders. Minimum for account orders is $15 ex clusive of pos tage and packing. All prices include Sales Ta x. A ll price s quoted are for this month only or until s tocks last. Add load protection to your power supply Do you have a dual tracking power supply? If you switch it on or off while a load is connected, you may damage circuit components in the load. This add-on board prevents dangerous voltages from being delivered by any dual tracking power supply when it is turned on or off. By JOHN CLARKE This is one of those projects that you may not have realised you needed - until now, that is. Let us outline the problem - and then we'll present the cure, which is this add-on board. All adjustable regulated power supplies use one or more op amps to control their main regulating elements. Fig.1 shows the general scheme for an adjustable regulated power supply. Essentially, it consists of a reference voltage source, Vref, an error amplifier, and the 66 SILICON CHIP & LEO SIMPSON series pass element, Ql. For a dual tracking power supply, such as the ± 50V supply described in the April 1990 issue of SILICON CHIP, the circuit arrangement is quite a lot more complicated but, essentially, it uses two series pass elements and two error amplifiers. The problem The error amplifiers are the cause of the particular problem we wish to discuss. Most op amps will work normally while their own sup- ply rails are within normal design values. Most designers run op amps with supply rails of ± 15V but they will work more or less normally even when their supply rails drop to ±3V. So provided the error op amps in an adjustable power supply have their own supply rails somewhere between ± 3V and ± 15V, they will operate as they should and the output voltage dialled up on the meter will be delivered to the output terminals. But what happens when the supply rails to the error op amp drop below ± 3V? The op amp loses control, that's what. Instead of acting as an "error amplifier" and closely controlling the series pass transistor (Ql in Fig.1), it loses control. And since the behaviour of op amps is not specified and is therefore not predictable, when their supply rails drop to low values, they often do the worst possible thing, and turn the series pass element(s) full on. This can mean that when you Fig.1: general scheme for an adjustable regulated power supply. The error amplifier compares the output voltage with a reference voltage (VREFl and generates an error voltage which controls series pass transistor Ql. turn a power supply off with the load connected, the supply voltage to the load may increase markedly just before it drops to zero. This can be a real problem if the load voltage was set for say, 5 volts, and the supply voltage jumps to 9 volts at switch-off. If the load was a TTL circuit, the chips could all be damaged. The situation can be worse if your power supply is set for even lower voltages. So far then, we have seen how the error op amps in a power supply can lose control when the unit is Facing page: this view shows the load protection board installed on the rear panel of the SILICON Cl-DP ± 50V Dual Tracking Power Supply. The unit can be fitted to virtually dual tracking supply, however. turned off. But the same thing can happen in reverse, when the power supply is turned on. And here, the voltage delivered to the load may be much higher than the setting you used on the last occasion, before switching it off. You can avoid both of these damaging scenarios if you remember to use the "load" switch on your power supply. That way, you turn the power supply on, adjust it for the desired output voltage, and then hit the load switch. When you switch off, you should disconnect the load with the load switch, before turning it off. But if you don't have a load switch on your power supply or you forget to use it, it can cause damage, as we have described above. And that's where our "Load Protection Switch" comes in. It is a small printed board con- 33 + 56 01 BC640 k.,. D1 B J'j· 2.2 + 63VWI 2x1N4004 02 . C The circuit of the load protection switch is shown in Fig.Z. As shown, it has component values to suit the ± 50V Dual Tracking Supply described in the April 1990 issue of PARTS LIST 1 PCB, code SC04204901, 60 x 70mm 1 2V relay with DPDT 5A contacts (Altronics Cat. S-4190) 8 PC stakes 4 6mm standoffs 4 machine screws and nuts to suit standoffs Semiconductors 1 BC640 PNP transistor 1 BC639 NPN transistor 1 BC546 NPN transistor 3 1 N4004 1 A diodes Resistors (0.25W , 5 %) 1 1 MQ 2 22kQ 1 1 00kQ 1 1 0kQ 1 56kQ 2 390Q 5W 100k 40VAC FROM TRANSFORMER SECONDARY How it works Capacitors 1 33µF 16VW PC electrolytic 1 2.2µF 63VW PC electrolytic 1M ---------'IW..-----0+60V 16VWJ taining a relay and a few other components and it can be installed in almost any regulated power supply. It is wired in to delay the connection of voltage to the supply output terminals whenever the supply is turned on. And it disconnents the output terminals of the supply immediately it is turned off, so that those damaging jumps in the output voltage just don't get to the load. In effect, it is an automatic load switch. RLY1~ .,. .,. l~ +L0A0 OUTPUT -LOAD OUTPUT EOc BOE BC546 BC639 BC640 VIEWED FROM BELOW POWER SUPPLY LOAD PROTECTION SWITCH Fig.2: the circuit uses D1 & D2 to rectify the transformer secondary and forward bias Q3. However, before Q3 (and thus RLYl) can turn on, the 33µ,F capacitor must charge up from the + 60V rail via a lMD resistor and turn on Q2 & Ql. Miscellaneous Solder, heavy duty hookup wire. SILICON CHIP but it can be adapted to almost any supply. It works as follows: Dl and DZ monitor the voltage from the transformer in the power supply. When power is applied, Dl and DZ rectify the AC and produce a DC voltage across the 2.2µF capacitor [with 40VAC the DC voltage will be about 60V). This applies a bias voltage to the base of Q3 via the ZZkQ resistor. This would normally let Q3 turn on to JUNE 1990 67 time of switch-on of the relay, but Q3 controls the time it switches off. The two 3900 5W resistors act as dropping resistors so that the voltage applied to the 12V relay is correct. As presented, the circuit would be suitable for almost any power supply with main (unregulated) DC rails up to 60V. For lower supply rails, the 5W dropping resistors would have to be reduced in value to allow the correct voltage to be applied to the relay. The two 390!] 5W resistors should be mounted about 1mm proud of the PCB to allow cooling. Be sure to use heavy duty cable for the input and output connections. power the relay but before that can happen, Ql must also conduct. Ql can't turn on initially because it is turned on by QZ and QZ can't turn on until the 33µF capacitor is charged by the lMO resistor from the + 60V rail. It takes about a second or so until the 33µF capacitor is charged sufficiently to allow QZ and Ql to turn on. This switches the relay on and connects the output terminals of the power supply to the supply rails. When the supply is switched off, the 60V rail(s) will take quite some time to drop to zero but the supply derived by Dl and DZ will drop almost immediately, because it is stored in a very small capacitor (2.ZµF). So effectively, Q1 , QZ and their associated components control the Construction We have designed a small printed circuit board (coded SC 04204901, 60 x 70mm) to accommodate the components. Begin construction by installing the 8 PC stakes. Next, the transistors and diodes can be inserted with due consideration to the correct type and polarity as shown on the overlay diagram. The 5W resistors should be mounted 1mm above the PCB to allow cooling. Now install the capacitors and resistors, noting the correct polarity for the capacitors. Finally, install the relay. The PCB is now ready for installation into the power supply. We mounted the load protection board into the ± 50V Dual Tracking Power Supply mentioned above. The following installation instructions apply to this power supply and will have to be varied when mounting it in other supplies. The PC board is mounted on 6mm Fig.3: here's how to install the parts on the PC board. Be sure to use the correct transistor type at each location and take care with component orientation. 68 SILICON CHIP standoffs on the rear panel in the clear area between the heatsink and mains cable entry. There are four supply leads to be connected to the PCB plus the relay load contact connections. The 40V AC connections are made to the secondary of the transformer, while the earth connection can be at the centre tap connection of the transformer secondary. The + 60V connection is made to the spare PC stake near the positive side of the filter capacitors. The load connections to the relay are made at the plus and minus output terminals on the power supply PCB, using heavy duty hookup wire. The minus output connects to the - input of the relay and the - output of the relay goes to the load switch via the inductor and filter capacitor mounted on the load switch. Similarly, the positive output from the power supply PCB connects to the + input of the relay and the + output of the relay connects to the load switch via the inductor and filter capacitor located on the load switch. Testing Now the Power Supply Load Protection switch is ready for testing. Apply power and wait to see if the relay switches on after about one second. This should apply the load voltage to the input of the load switch. When mains power is switched off, the relay should immediately switch off. ~ Fig.4: this is the full-size PC artwork. WOOD FOR CHIPS ... WOOD FO R CHIPS ... WOOD FOR CHIPS ... WO OD F OR CHIPS .. WOOD F OR CHIPS ... WOOD FOR CH IPS .. WOOD FOR C NEW 2-Way~ -:S::. HUSKY EPROM Programmer Automatic/} • PC driven through a high speed Data ~ parallel interface • Four 32 pin ZIF sockets Switch ,, • Programs in Set or Gang mode ~i:s:~/oC~! (~~ ~ 'L0:·, up to four single EPROMs or four CMOS 20I24pm EPLDs ~ ~ ct 0 lJ.. Cl 0 ~ ~ ~ ct 0 lJ.. Cl 0 ~ ~ ::i: \..) ct 0 lJ.. Cl C) ~ ~ 5 ct 0 lJ.. Cl C) ~ printer automatically. -~~ The printer (or other peripheral) is allocated on a first-come-firstserved basis. LED indication tells you which PC is connected. No external power and can be easily attached to any surface using velcro pads supplied. Suits any PC and Printer with parallel (Centronics) connections using 0B25 connectors. $99.50 Manual Data Switches Total flexibility at very modest cost. 2 Way Seriaf (RS232) $45.00 Parallel (Centronics)$55.00 4 Way Serial (RS232) $70 .00 Parallel (Centronics)$80.00 Just Released ... AT&M25 Audio Modem Kit Intended for use with the ATM22/23 16 channel remote control kits. Allows communication via radio link (CB, walkie talkie etc), phone etc. Uses common V23 communications standard and FSK (1300Hz and 2100Hz) which is ideal for any equipment designed for speech. Automatically configures when connected to ATM22 or 23. High noise immunity. Crystal controlled. The ATM25 converts the 16 channels of parallel information into FSK serial form . Compressor circuit otters 20mV to 20V p-p sensitivity while output can be jumpered for 50mV or 1V. Quality components used throughout. Designed and produced locally $66.60 We stock the full range of AT&M kits including .. Low cost accessory for your scope. Converts incoming analog signals up to 20kHz into a stream of 8-bit data words for storage in 2048 word memory. ldeal•for one-shot observations. Replay as many times as you like. See description in E.A. December. Complete kit (AT&M17) using top quality components and with full instructions is just $193.80 Matching case (ATM17-01) $27.60 Kikusui COS5020 20MHz scope down to $882.90 (That's nearly S100 ott!) COS5041 40MHz scope down to $1372 .60 (that's over $150 off 1) Also the COS5060 3 channel 8 trace, 60MHz scope at $1859 .55. YES Our prices include Sales Tax! i5 ct a lJ.. Cl a ~ PORTASOL PROFESSIONAL SOLDERING KIT See E.A. April 88. No cords or batteries yet it gives the equivalent of a 10 to GOW iron. You can get up to 90 minutes average continuous use from a single fill. Tip temperatures as high as 400°C can be set. The kit includes one soldering tip, a hot knife, hlow torch and hot blow. Cap contains a flint lighter. The complete kit comes in a handy case (with stand for the iron) which just about fits in your pocket. $79.95 PORTASOL STANDARD SOLDERING IRON We've sold hundreds of 'em to servicemen and technicians. Complete and ready to use with just the iron and bit $39.95. 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Basic Ranges Vdc 400mV to 1000V (03%) Vac 400mV to 750V (0.5%) Ade 400mA (100µA) to 20A (0.5%) Aac 400mA (1 OOµA) to 20A (0 5%) n 4000 (100mn) to 40Mn (0.5%) Great Value at ONLY $144 This is an.MS-DOS software and cabling package which enables technicians and engineers to perform serial data comms analysis. It otters sophisticated problem solving facilities at a fraction of the cost of dedicated hardware systems. SerialTest provides a window onto RS232 lines operating either as a passive observer or actively sending data or control signals to simulate either at DTE or DCE device. 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"COMTEST" - The complete RS232/ V24 Troubleshooter Europe's most popular high quality RS232 tester will save time and trouble because it checks ALL the lines on any RS232 equipment. • Tristate monitor all 23 signal lines • Breaks and redirects all 25 lines • Ground voltage differential testing between DCE-DTE • Four level bi-directional current loop test • Simple operation - no batteries Corniest has 25 OIL switches with DTE and DCE interface pins on both sides. Break and patch all 25 lines with switches and jumpers provided. Instructions clearly printed with abbreviation guide to aid identification of connections. All contacts are gold plated . Comes in transport pouch with 8 jumpers. De~igned in Sweden and compares favourably with testers costing over $500. Well worth $315.00 ~ a 0 a "" :0 (") :t: ~ ~ a 0 "" O · :0 (") ::i: 'ii V) ~ a 0 "":0 a 2 j ~ a 0 "" a :0 (") :t: j ~ a 0 a "" :0 (") ::i: ~ ~ GEOFF WOOD ELECTRONICS PTY LTD a 229 Burns Bay Road, (Corner Beatrice St.) INC IN Nsw Lane Cove West, N.S.W. P.O. Box 671, Lane Cove N.S.W. 2066 Telephone: (02) 428 4111 Fax: (02) 428 5198. 0 :0 8.30am to 5.00pm Monday to Friday, 8.30am to 12 noon Saturday. Mail Orders add $5.00 to cover postal charges. Next day delivery in Sydney add $5.00. All prices INCLUDE sales tax. Tax exemption certificates accepted if line value exceeds $10.00. BANKCARD, MASTERCARD, VISA, CHEQUES OR CASH CHEERFULLY ACCEPTED 0 "" (") :t: ~ COMPUTER BITS By JENNIFER BONNITCHA What to do when your computer goes bung; Pt.2 This is the second part of an on-going series about problems with personal computers and associated hardware. Since the type and number of computers, printers and various peripheral devices is enormous, the series will concentrate on some of the most common problems. In particular, we w·n cover some of the elements of the Central Processing Unit (CPU) (such as the power supply and motherboard), monitors, keyboards , printing devices and hard/floppy discs and their drives/controllers. We will also look at some software suggestions since hardware problems are often directly or indirectly linked to software problems. Of necessity this series, and in fact the entire column, tends to focus on the IBM and compatible market. The reason is simple. It is by far the most extensive and my experience is primarily with, but not exclusive to, this style of machine. I have been known to PIP with the best of them but sadly, in the business world, those days seem to have gone forever. Sure there are lots of happy Vegemites out there using home computers - they've been around much longer than the "traditional" PC. The problem is to keep as many people interested and happy as possible at the same time. You all know the line about pleasing all of the people some of the time and some of the people some of the time. Well in this instance, prepare yourself for the latter. Back to the task at hand, just 70 SILICON CHIP what can go wrong with your PC? Lots of things! The trouble is that for every problem you manage to solve, clever users find ways to keep coming up with new problems to tax their hardware and software - not to mention the grey matter of various technical support staff. Whenever you are presented with a problem, approach the task as logically as possible. Resist the urge to leap right in and tear the system apart. A cool, sensible approach is vital. Make notes as you go along, particularly if you need to change switch settings on the PCs, printers etc. Troubleshooting rules Basic problem determination involves several steps: (1). Check the installation and configuration. Make sure the correct cables are plugged into the right holes. Often on compatible PCs, the various outlets are not labelled. Additionally, you may have several add-on boards installed, each with similar-looking connections. (2). Check the installation and configuration of the software. Make sure that the correct printer, printer port, graphics board, monitor, mouse type, keyboard, etc has been selected. (3). If you still have a problem, work through the system bit by bit. Printer problems could stem from any number of components. Check that the cable is securely attached to both the PC and the printer. Make sure you are using the right cable. Make sure the printer is turned on and selected (no groaning please, sometimes the most obvious causes the greatest problem). (4). Check the simple, inexpensive things before the more complex and more expensive items. Change printer cables before trying another printer, for instance. (5). Check that the power supply does not suffer from interference, causing the computer to crash. If the screen image appears "wavy", move the monitor around. If the image improves, you could have power interference. (6). Read the manual. There is a reason for putting this as the last step. It is usually the last resort. Most people seem to have an inbuilt aversion to reading the manual. It's surprising how much information is contained within - and most of it is really good stuff if only you could make head or tail of it. Intermittent problems are by far the most irritating. Frustrating to the nth degree and difficult to duplicate, there is not much you can do unless a few simple steps are followed. Whenever possible, write down any messages from the computer, what happened immediately prior to the problem, and take a screen dump if possible (press either SHIFT PRTSC or the PRINT SCREEN key). Interpreting a user's description of what happened can be more difficult than actually solving the problem. Encourage the use of technically descriptive terms wherever possible so that each knows what the other is describing. In terms of failure rates, some items are more susceptible than others and notable amongst these are mechanical devices such as disc drives and power supplies. The irritating thing is that they sometimes fail with absolutely no warning. Memory devices can also fall into this category. Mean Time Between Failure (MTBF) is a rating expressed in thousands of hours. The figure given for computer devices is derived statistically from the results of tests carried out by the manufacturer. The device is subjected to various extremes of conditions in order to estimate how long the device can function before it fails mechanically. So in roughly "failure rate order" the following are most likely to cause you headaches: (1). Power supply; (2). Low level hard disc format; (3). Floppy disc drive; (4). Hard disc controller card; (5). Hard disc drive; (6). Memory chips. This series will examine all of the above. Remember that simple things can create the greatest problems. Running a computer all day while it sits at a nice sunny window (don't we wish!) can cause considerable overheating. This can lead tci premature aging of both mechanical and electronic components. If your computer is positioned in a corner where air doesn't circulate freely, you can also create overheating problems. Likewise with monitors covered in little bits of paper. It may look cute, but unless it is cooled efficiently, problems can develop. My computer won't work Sometimes you get a plaintive voice at the other end of the telephone, crying out for help. Many problems occur at boot time. During the Power On Self Test (POST) sequence, your computer takes itself through a rigorous Write protect notch ~ (some diskettes do ~ not have this notch ) !l Permanent - - label Exposed recording surfaces Diskette in permanent protective jacket Diskette envelope Your floppy discs should always be stored in their jackets. Never attach notes using paper clips - they can become magnetised. Use a stick-on label instead & write with a felt-tipped pen. series of steps to help ensure that at I.e ast all the hardware components are functioning. Each step is reliant on the successful completion of the previous step. If you do experience a problem during the POST, try it again and this time watch what happens. Try to determine how far into the POST the computer goes before it fails . As . a general indication, this is what happens: • You turn on the power. The computer performs a self test only when full operating power is reached. If you get no further than having fans and discs spinning, together with power to the monitor, you could have a problem with the power supply. Provided all is OK, a power good signal is sent to the motherboard. • A timer chip stops generating a reset signal for the processor when it receives the power good signal. • The processor starts to execute the instructions found at memory location FFFF:0000. Its main function is to provide a direction instruction to the BIOS start location. • ROM BIOS starts then checks flags at locations 0000:0472 and 0000:0473. These flags indicate whether you are performing a cold or warm boot since different POST procedures apply. The warm boot skips most of the POST procedures. • Once POST commences, all major components are tested, including the speaker (when the computer beeps). Problems are indicated by messages to the screen and beeps. • BIDS then performs a ROM scan to find various adapter cards. Adapter ROMs can alter existing BIOS routines, thus establishing new ones. • The BIOS now searches for a boot record on track 0, sector 1 of the first disc drive. If there is a disc present in Drive A, the BIOS attempts to continue the start procedure. If the disc is actually a data disc inadvertently left there since the last time you used the computer, you will get the message: Non-system disc or disc error. Replace and strike any key when ready. Replace the disc with a DOS system disc (ie, a disc with COMJUNE 1990 71 COMPUTER PART# SIZE AMIGA AMIGA AMIGA 02930 02932 02938 3.5" 5.25" 3.5" CAPACITY 880K 360/880K 880K AMSTRAD 02904 3.5" 720K ATARI ATARI 02916 02918 3.5" 5.25" 720K 3601720K IBM IBM IBM IBM 02946 02948 02950 02952 3.5" 3.5" 5.25" 5.25" 720K 1.4MB 360K 1.2MB WITH WITH WITH WITH TOSHIBA TOSHIBA ZENITH ZEN ITH 02970 02972 02976 02978 5.25" 5.25" 5.25" 5.25" 360K 1.2MB 349 .00 399 .00 360K 1.2MB SUIT TOSHIBA LAPTOP SUIT TOSHIBA LAPTOP SUIT ZENITH SUPER SPORT SUIT ZENITH SUPER SPORT COMPAQ COMPAQ 02980 02982 5.25" 5.25" 360K 1.2MB SUIT COMPAQ SLT 286 SUIT COMPAQ SLT 286 349.00 349 .00 COMMENTS PRICE WITH ON/OFF SWITCH WITH ON/OFF SWITCH INTERNAL KIT FOR A2000 249.00 299.00 229.00 FOR PC1512/1 640 269.00 WITH POWER SUPPLY SWITCHABLE , WITH POWER SUPPLY 269 .00 299.00 ADAPTER ADAPTER ADAPTER ADAPTER INTERFACE INTERFACE INTERFACE INTERFACE & & & & CABLE CABLE CABLE CABLE 299.00 329 .00 299.00 329.00 349.00 399.00 ALL TOSHIBA/ZENITH/COMPAQ DRIVES INCLUDE EXTERNAL POWER SUPPLIES, INTERFACE AND CABLES WE ALSO HAVE A RANGE OF DRIVES FOR OTHER BRANDS SUCH AS APPLE AND MACINTOSH AS WELL AS A RANGE OF BARE DRIVES IN 360K/720K/1.2MB/1.44MB/2.88MB FORMATS Have you seen our catalog? Write or phone today for your FREE copy. Over 100 products shown with full details and specifications! BEWARE! We are aware of some cheap drives coming from Taiwan, usinB inferior drive mechanisms. REMEMBER: ALL ROCTEC drives use UALITY Japanese mechanisms and are covered by a 12 month warranty. The drives are supported by us under an exclusive agreement with the manufacturer. DEALER ENQUIRIES WELCOME Plii[ [eeson 's PERSONAL COMPUTER MARKETPLACE PHONE (02) 418 6711 FAX (02)4186713 Mail Order Address: P.O. Box 1100 Lane Cove NSW2066 FREIGHT CHARGES Include $10 with order for all normal items· heavy items, e.g. monitors add $15. 14 day money back guarantee Order by phone (use credit card), by fax or by mail. Unless insurance is declined it will be charged at 1% of total purchase. This is for your protection. PRICES VALID AT 1 MAY 1990 Ptyltd Sealed chamber Mounting chassis Read/wrile head Cut-away view of a hard disc drive. Although more reliable than floppy disc drives, they can fail so always make back-ups. MAND.COM on it) or remove it from the drive, then press any key to continue. • The BIOS now looks to the hard disc for a master boot record and if found, the sector is loaded and the program executed. • The boot record now takes control from the BIOS to load xxx10.COM and xxxDOS.COM. At this stage xxxIO.COM is firmly in control. • xxxIO.COM uses xxxDOS.COM to load and pass control to the discbased command processor, COMMAND.COM. e COMMAND.COM loads and runs the AUTOEXEC.BAT file, if present. e AUTOEXEC.BAT processes all the commands contained therein and finally displays the DOS prompt or a menu, as the case may be. Typically, problems are found during the POST checking phase and I when the BIOS requires a boot record. Mostly, the POST problems are memory or device related. Further problems can be experienced with discs left in Drive A and faulty or deleted COMMAND.COM files. Try booting with a DOS disc in Drive A if you can't get to the final stages, and note any messages from the computer. Disc disasters Discs create more obvious problems than most other PC components, so it seems like a good idea to start here. Naturally, we are all smart enough not to fold diskettes in half prior to mailing - but is the post office smart enough to deliver them in the same condition? Make sure you use a disc mailer to send diskettes through the post. If this is not possible (or you're too stingy), pack the disc with reasonably stur- • o- The 3 + -inch micro discs are more robust than their 5-25-inch cousins since they have the advantage of a more rigid case and a sliding metal protector for the read/write area of the disc. dy cardboard and bubble-wrap (if available). Should you have the misfortune to receive a disc that has been folded or creased, try to ease out the wrinkle in the disc cover. This is usually what stops the disc from spinning correctly. Once the cover is fairly straight, you will often find the data accessible. Copy the contents as soon as possible then discard the disc unless you like to live dangerously. Another possibility is to very carefully open the damaged jacket and place the disc in a new jacket. This has worked successfully once only, but desperate people need desperate solutions. Once again, copy the contents and discard the old disc. Discs of all types should avoid a trip through the X-ray machine at the airport - although I do know of several cases where discs in plastic boxes have been through and survived unscathed. The amount of damage likely to occur is inversely proportional to the number of backup copies available. If you have no backup, it is sure to be ruined. Floppy discs should avoid magnets of all kinds - particularly paper clips stored in those cute magnetic holders on the desk. Floppy discs don't know this, of course, so you have to make sure that they are not placed in harm's way. Don't put paper clips on 'em! If you must attach a note to the disc, use Post-it notes or similar. They are easily removed and create few problems. Likewise, keep your discs in their jackets and in a box, not on the floor where the legs or wheels of a chair can maim and destroy data at an astonishing rate. Generally, you should not have any problems, but err on the side of caution and copy the contents ASAP. The 3 + -inch micro discs are more robust than their 5.25-inch cousins since they have the advantage of a more rigid case and a sliding metal protector for the read/write area of the disc. You will have less problems with dirt and dust contamination using these discs, but remember at all times that nothing and no-one (least of all me - Backup, what's that?) is perfect. ~ TUNE 1990 73 tt Hig!:~~~~~!~~! W!~Rl~~t OUR l ~ AT/ 386 Hard Printer Cables Disk/Floppy Disk Controllers Ridiculous prices!! cAT Acos 21 metrecable CAT. LACPP5 5 metre cable CAT. 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After everal letters and telephone calls, was invited to the head office for n interview by the owner. 1st February, 198Australia. loggs & company Dear Colin, A new decade, a new state, a new job - several of them! It's been a long time since last I wrote, and quite a few things have happened. As you may recall, I was thinking about going back into broadcast television. Indeed, I'd sent a couple my background was excellent but the station manager knocked me back because I wasn't working in the industry. "If only you were working for a station," he said. I couldn't believe it. "Listen mate," sez I, "if I had a job, I l Fred Bloggs had worked for a ulti-national company and had cided he'd never get rich unless ran his own outfit. He took pride being a practising engineer. His rtner was a sombre, taciturn ke with a similar background. !though they'd had an agent in country area - an electrician they knew they were losing a lot o usiness because the buyers had ~o~fil~e~tt~eJr;s io~ff~-iO ~e~ o~ f im re~f~e~r:en~c~e~s:_..~w~o~ul;drn~•~t~b~ou ei l~o~o~ ~ ·at ~ ! ftime, ~:: ~ ~- :either 1ttle confidence in Melbourne dealing with was a bloke I: nused to~yf wo tkm another the Sydney or ofrac of him. friend told me of a possibility he'd £ices, because of the distance and Well he telephoned me and asked been offered. He didn't want to let delay. if I'd like to come to work for him. go of the seniority he'd built up Fred was a little sceptical about He'd gone to pleasanter climes and where he was. So I had a bash. taking me on. was now the chief engineer of a This outfit sold television gear "But you've never done any sellcommercial channel there. I jumped a bit to broadcast stations but more ing," he said. at the chance - he's a great bloke! in the closed-circuit area - and I pointed out that the electrician Following his instructions, I sent a was also involved in security/ hadn't done much either and said: resume to the station with a cover- surveillance work. They were after "You need someone with a good ing letter. a local representative with tech- technical background to deal with About a fortnight went by and I nical knowledge to sell to new bewildered clients". got another call from him. Seems clients and service existing ones. "Give the customer the right information," I said "and he'll sell himself''. There was a big contract coming up for a surveillance system in a prison. I guess my exposure to the security industry was the deciding factor, and my general knowledge of television systems. Later, By however, I decided it was "mug e RICHARD KOPF ers 76 SILICON :HIP WE:.'~~ \N MORfZ. S"r~\F~ "l"HAN Ne='D •<E.L-l--'1' eO ~fj'{!, oo•A'-ONG A&001"' "{M~l\l, I Ga\ A F~tJi"\G CAl-L- PR.ON\ ~&'Do•• time" and almost any warm body would have done. I had a million questions but all were shrugged off at the time: "We'll send you photocopies of all pertinent info". Patting me on the head, they put me in a taxi and sent me off to the airport. Pathetic technology All I had to do was start a state office from scratch - a one man operation - win this big tender, and capture more business. The first broken promise concerned the company car. The accountant, a pudgy little bloke named Willem, telephoned to say there was a problem with the leasing company. "Just use your own vehicle and send us the receipts for petrol". What's a car allowance? Insurance, rego, repairs, all the rest, Pathetic Technology had never heard of it. PT? Oh, that's what the customers called us. I found out their opinion soon enough. Now, PT hadn't done any forward planning. I managed to get a news item in the business section of the local newspaper. That was probably a mistake, as I soon started getting calls from irate clients. You know the kind: "When's that bloody warranty repair going to be finished? I've been waiting over three months, and only had a fortnight's use". I should be fair. They had managed to arrange desk space at a local firm, with one telephone line allegedly reserved for PT calls. As far as receiving information about the customer base, I got that from the customers. The post office box, bank ac- count, petty cash and demo stock were not forthcoming. Each weekly report itemised the sundry bits and pieces for on-site work, petrol, advertising charges, and pro-rata costs from the place I hung my hat. Each week, I was further in debt. The hundred dollar advance I'd gotten initially didn't go far. Separate notes to the accountant elicited no response. One day, I told the telephonist I was going home, though it was only 10am. "When will you be back?" "Maybe never!" As I'd anticipated, a couple of days went by before the head office got word my state "office" had shut. I got a call at home from Bloggs. "What the bloody hell are you about, mister?" "Why, Fred, good to hear your voice. The problem is, boss, I can't afford to go to work. I'm ashamed to show my face at the office". "Why? What have you done?" Naturally, he assumed that I was the problem. So I enlightened him as to the facts of life: "Your accountant hasn't paid those people for desk space or telephone charges. They won't let me use the fax machine any more. I don't have any money to put petrol in the car". There was a long silence. "Aside from which," I continued, "my last pay is overdue, the first month's was short, I haven't received any reimbursement for eight weeks of running my private car, and Willem won't return my calls or answer my letters". I paused and waited for his explanation. There was another long silence. "It's your money," I finally said. "But if it were me, I'd not make an STD call just to sit in silence". A much subdued Bloggs said, 'TH take care of it. Why didn't you tell me about these little problems?" "Because I shouldn't have to get what's coming to me by ringing the managing director with every whinge". "Get the office going again. Customers are starting to talk!" JUNE 1990 77 THE TECHNOLOGY LETTERS - CTD "Fred, they were speaking their piece well before I arrived on the scene. You know, the only way I found out about the existing customers is when they called me to complain". He said he'd sort out all these problems and things would go smoothly after this. Well, a couple of days later, I did get a cheque for the shortages and the reimbursement. Along with a stroppy note from Willem. About six weeks later, I was on the phone to Bloggs yet again. "Same time, same channel, Fred". Despite all the petty bickering, I was managing to get a few things accomplished. I chased outstanding repairs for customers, sold some small systems, and got a contract for some upmarket colour cameras. I'd met the necessary people in the various government departments. The blokes who bought the cameras had gotten to know my background and asked me to design some circuits for them. As my salary was so low I deem it my privilege not to disclose it, I accepted. A couple of little projects done at home in the evenings seemed to work well. One thing led to another. They filed for a subsidiary business name, with my name on the form also. Frantic Fred Along about then, I got a frantic call from Fred. "We're in more strife than Ned Kelly, Dick. Can you come over and help out with a telecine job at a customer site?" I never mind travelling, so like a fool, I said yes. They booked a ticket for me and the next day I was on my way to the big smoke. Seems as how they'd won a tender for some broadcast quality equipment. To save money, they'd subcontracted the installation and commissioning to an electrician. To make a long story short, I had to do a complete re-installation, right down to positioning the plinths for projectors and the 3-gun camera. No wonder they'd never 78 SILICON CHIP been able to achieve a decent focus. Also, the head office broadcast sales engineer had said they could run at a higher target voltage than the manufacturer recommended "to get more signal". Yeah, along with noise in black (you call that black?). It was only after all this square one business that I found out the final lurk. They'd told the technical officer on site it was OK to substitute the projection lamp in the slide unit. He'd grumbled about heat build-up. [Of course, the manuals said the unit should not be fired up continuously. When all else fails, read the book!) I finally found out about this swap, and managed to get a squiz at the original lamp. It had a vertical filament structure, whereas the substitute was horizontal. Going back to the original solved the shading problem. We'd been maladjusting the chain, trying to compensate for the irregular light field created by the non-standard lamp. It turned out that the manufacturer had a field lens that was designed to cope with the proper lamp. When we'd get the slide image reasonable, the film projectors were woeful. Once we'd "done it over," all was well. The day I'd walked in, they hardly wanted to speak to me! "Another pathetic wonder," the tech officer had said. By the time I left, they were so pleased with the results, they placed a $40K order for more goodies. I inquired as to whether I would share the commission. "It's not your state," Fred responded huffily over the telephone "nothing to do with you". Continuing, he said: "The reason I called you is that we have a similar problem here at head office. Come on up here and fix that one for us". "It's not my state," I murmured. Fred got a bit exercised at that. Guess he just doesn't understand Yank humour. In the end, of course, I went walkabout once more. Living out of a suitcase for six weeks surely made me appreciate your sort of lifestyle, Colin. The fact that it was during the school holidays seemed to mean nothing to my glorious and generous employers. By the time I got back home, Carol almost wasn't speaking to me. I expected the three girls to say, "Mommie, who's that strange man?" Jailhouse blues We were close to the deadline on the prison job. I'd done an early site inspection before the trip. It's a bit creepy walking around a jailhouse; some of the inmates gave me really friendly smiles. I don't think I'd like to reside there! Having sent my notes, copies of tender documents and other junk to Fred, I received no response. Surprise! The bloke in the government office telephoned to ask why we'd not yet tendered on the job. I stalled. Just before the closing date, the national sales manager called to say he was coming down to sort out the problems. What problems, I wondered, that they hadn't made themselves, for themselves. "Make me a few appointments with important clients". I did this, only to have him cancel most of them when he arrived. "I want to go see me mate so-and-so". He did, however, manage to file a request for extension of tender date on the prison job. A couple of days later, I called in on one client I'd dragged our hero to. "Who was that idiot you brought in here the other day?" I replied that it was my boss, the national sales manager. "Well, don't bring him here again if you want any more business from us. The man is stupid!" Fred called to tell me not to worry about the tender; they were doing it themselves and submitting it direct. A couple of days later, the bloke in the government office called. "Congratulations, you've won the job". No sooner had I put down the phone than it rang again. "Can you pick me up at the airport?" my glorious leader asked. It surely seemed curious he'd arrived just at that time, and without tS 11-\E.~~ A H~:r AM 'I, ,-~CHNICI AN &0tl-~1~G?~.L.5=~ GN\ ·. ti .... . ....... . ·.;ti. .a 0 " . ~~ ... g,=·-·· ~--~-0 _I ~ ~ 1HA""r 8tRD & t. v1DN'""r' advance warning. You would not be surprised to learn that he'd come down to close the state office. "We're not getting enough business out of this area," he explained. "Here's a cheque for a month's pay in lieu of notice". "What about my commissions on the colour cameras, the education centre and the prison job?" "As we've not received final payment on the first two, and you're no longer in our employ, you aren't entitled to anything. And the prison job, we did all the work ... " Later, I found out the probable reason that Fred had decided to dump me. He'd left his big employer way back when to start his own company - taking a few jobs with him. I guess my moonlighting work seemed uncomfortably close to history maybe repeating itself. Country TV Within a few days, I received a telephone call from the station that didn't want me because I wasn't working in the industry. "We've had a restructure up here and are in need of an additional senior technician. Come up for an interview". Nothing ventured, nothing gain- 6 c;e:,.,- AL-ONG ••. ed, I thought. So I told Carol maybe we'd think seriously about moving interstate, again. It didn't give me great confidence to discover that my mate had left their employ. They'd had delusions of grandeur and had promoted one bloke to group engineering manager. That was when my mate had become chief engineer. Several problems quickly reared their ugly heads. A couple of the other people thought they should have been selected. They started angling for over-award payments. To kill two birds with one stone, management decided to call them assistant chief engineers, give them an over-award payment as salary, and put them on rostered on-call status. The second problem was that the engineering manager did not manage. When it came to the admin side of the job, he was nowhere to be found. He never turned in his reports to the board and every time the general manager went to find him, he wasn't in his office shuffling papers, like a good little executive. Rather, he couldn't wean himself from the bench. It does seem difficult for a self-styled genius to delegate work he used to do himself. So, the board decided they didn't need his executive services and relegated him to chief, once more. My mate had been offered the opportunity to continue to work for them, as one more assistant chief engineer. Aside from loss of title and status, he had to accept a pay cut - and surrender his company car. Not to put too fine a point on it, he'd declined. A job's a job, I thought. And it is an opportunity to get into television work again. So, I found myself on the usual 3 months' probationary period "to see if I'd work out" . Starting into a new town, a new job, and being on my own for an indefinite period was none too easy. Carol was locked into a contract job, and we decided it was best to let that get completed and wait until the end of the school year to move the family: less hassle for the girls. "We'll help you find suitable accommodation," the G.M. had promised. Two days after I started work, the chief was whinging about the expense of keeping me in a hotel room. Mai the chief Malcom, the chief, was known to the others as Mal Content. As the lone senior technician, I found myself actually in limbo. There wasn't a chain of command to $peak of. One assistant chief was so involved with community service work and other moonlighting commitments, he was rarely at work. The second was too shy to give orders to the two juniors on the staff. The third was always out, either "buying parts," at the transmitter, or going to a translator site. Mal usually flew the engineering department by the seat of his pants. No forward planning was in evidence. Everyone worked 9 to 5. With production during the day, there was never the opportunity to do preventative maintenance. The only time you got to fix something was when it broke, and two or three production staff hung over your continued on page 99 JUNE 1990 79 Jl '\l l\., .::,..J /"'1\..,/-\n .JAYl...,1-\H. l:Lt:.L, IHUI\IIL,;;:,J r\ l\..,f-\ n C LCV 1n v 1-..1v .:,...rM 1vr-,.n C L t.. ..... 1 nv,-. , ..... vvl"'\ I\JMn 1.-l..l..V l l\>.J l '< I VVV'"' ' ,._,,.... , , L.L.. L.. V II \Vl 'O I,._,........,,,,...,, .. , .... ._.... ..,. ,, ,..., ,., ,_,......., , , ....,, "• ............... . . . ...... . . .......... _ . . .................... .... . , ...... . . ........ "' )NICSJAYCAR JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS.JA YCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICS.JA YCAR ELECTRONICSJAYCAR ELECTRONICS J l NICSJAYCAR JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRO NICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS J )NICSJAYCAR JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS J )NICSJAYCAR JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS J ) NICSJAYCAR JAYCAR ELECTRONICSJAYCAflELECTRQNICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS J )NICSJ. - --- ---- - -- - RONICS J )NICSJ. )NICSJ, )NICSJ, )NICSJ, Many items below cost! )NICSJ, Stock is limited, there may not be all the items in all stores. lNICSJ, lNICSJ, If your nearest Jaycar showroom has sold out of the item you want to purchase, you can phone (021747 1888 and they will advise which stores lid that lNICSJ, l NICSJ, particular product in stock at the beginning of the sale. You can then phone around yourself, or you can place an order with our mail order dept. on (021747 lNICSJ, 1888 using a credit card and we'll do the finding for you and send you the goods. lNICSJ, For full specifications and descriptions check our 1989 catalogue. Be quick, stock is limited and won't last. JNICSJ JAYCAR'S DISCONTINUED PRODUCT SELLOUT lNICSJ lNICSJ, l NICSJ, l NICSJ JNICSJ, lNICSJ, )NICSJ, lNICSJ, lNICSJ, ;~:g~: lNICSJ, lNICSJ, lNICSJ >NICSJ, >NICSJ, >NICSJ, >NICSJ, >NICSJ, :~:~~ >NICSJ, >NICSJ, >NICSJ, >NICSJ, >NICSJ, >NICSJ, >NICSJ, >NICSJ, >NICSJ, >NICSJ, >NICSJ, >NICSJJ >NICSJ, >NICSJI >NICSJI >NICSJI >NICSJJ >NICSJI •NICSJI •NI CSJI •NICSJI •NICSJ/ •NICSJI •NICSJ/ •NICSJ/ NICSJI NICSJ/ NICSJ/ NICSJ/ NICSJ/ NICSJ/ NICSJ/ NICSJ/ NICSJ/ NICSJP NICSJ/1 NICSJ/1 NICSJ/1 NICSJ/1 NICSJ/1 NICSJJ\ NICSJ/1 NICSJ/1 NICSJ/l NICSJ/l NICSJ/1 NICSJ/1 NICSJ/1 NICSJ/1 NICSJA ~:g~: ~:g~: '1ICSJ/I \IICSJA \IICSJ/1 \IICSJ/1 ~:g~~ 'JIGS.JA 'JIGS.JA ~:g~~ 'JIGS.JA 'JIGS.JA AA0310 AA0315 AA0320 AA0346 AA2023 AA2096 AS3035 AS3042 AU3855 AM4065 AM4076 AM4119 AM4120 AM4134 BS0416 BS0602 BM8501 BM8502 8M8503 8M8504 BM8510 BM8514 CM2086 CW2104 CW2112 CW2120 CW2128 CE2333 CF2756 HPl 106 HP1185 HP1205 HP1220 HA5230 HR5235 HK7100 HG9911 HG9912 HG9913 HG9914 HG9922 HG9924 HG9928 HG9940 HG9952 HG9989 HG9990 HG9992 KA1650 KA1681 KA1694 KA1695 KA1700 KA1715 KA1716 KM3016 KM3040 KM3056 KM3060 KM3063 KM3064 KE4725 KE4731 KC5015 KC5024 KC5027 KC5044 KC5047 KC5048 KC5049 LT3016 LT3140 LT3180 LT3194 LT3810 LT3830 LA5095 LR8810 LA8840 MF1000 MF1015 MF1033 MF1042 MF1045 Stereo Amp BO+BOW AMS Built 169.95 Hi-Fi Pre Amp Bi Fet Built 84.95 Speaker Protector- Mono Built 27.95 Remote Control - Infra Red Built 52.95 Delux Headphones 59.50 Car Aerial Ext 3.5ml 6.95 7x5"spkMetalGrill 3.95 Redford 20 W Outdoor Spkr (ea) 149.00 Ultrasonic Transd - for car alarms 19.95 DM904D Bal Lo/Hi Imp Mic 115.00 W'less Xtal Mic 139.50 Mic Desk Stand 4.95 Mic Desk Stand 27.95 Mic Windshield - Largest Size 6.75 Mac Programming Techniques 29.95 Microcomp for Business Appl. 19.95 8080A/8085A Microchart 11 .95 6502/65XX Microchart 11.95 54/7400 Microchart 11.95 Algorithm Microchart 11.95 BASIC Introduction Microchart 11.95 How to Sample Microchart 11.95 Vifa Dome Midrange 129.00 5· Woofer - Midrange 15W AMS 18.95 8" Polycone Woofer Sq Frame 49.95 10" Polycone Woofer Sq Frame 64.95 12" Subwoofer- Dual Voice Coil 149.00 8JX Magna 8" T/cone 40WAMS 34.95 Gold Spk Cloth lmt x 5' 3.95 Led Bezels - Hi-Fi Quality PklOO 26.95 lnsul Staples PklOO .75 28m Adhesive Cable Tie mt Pk 258.50 BNC Insulators Pk 4 2.00 Rack Frame 30 Unit 189.50 Panel Set for 30 Unit 129.00 Collet Black Knob Hi Oual 2.00 18 DIL Pattern Bishop Graphics 6.50 24 DIL Pattern Bishop Graphics 6.50 28 DIL Pattern Bishop Graphics 6.50 40 DIL Pattern Bishop Graphics 6.50 TOS T/ Sista Pat Bishop Graphics 6.50 T018 T/Sista Pat Bishop Graph 6.50 Target- Universal Bishop Graph 6.50 Tape .23" 20yd Bishop Graphics 6.95 .156" Edge Conn. Bishop Graph 6.50 Scotchcal Alum/Red -8001 11.95 Scotchcal Plas. Red/White 11.95 Scotchcal Pia. Blue/White 11.95 Playmaster60/60 Amp Kit 329.00 3 Band S/Wave Radio Kit 79.50 VolVContinuity Tester Kit 19.95 AC/DC Millivoltmeter Kit 46.50 Power Transistor Tester Kit 22.95 Car Brake Lamp Monitor Kit 24.95 Auto Tune Up Adaptor Kit 29.95 RTTY Encoder Kit 32.50 Dual Speed Modern Kit 139.00 100 W Mod ETl5000 Less Mosfet89.50 Balanced Line Driver Kit 99.50 Uo Satellite Decoder Kit 59.95 Octave Equaliser Module Kit 59.95 Sold Iran Temp Control Kit 39.50 Telephone Intercom Kit 49.95 Telephone Ringer Kit 19.95 Modem End File Ind Kit 9.95 PH Meter Kit '49.95 Car Safety Lights Kit 29.95 Beta Tester Kit 18.95 Telephone Bell Monitor Kit 16.95 Aux Brake Lamp Flash Kit 17.95 UHF.VHF Band Separator 5.95 UHF Indoor Antenna 24.95 10 Element UHF Antenna 59.50 TV Gutter Brkt + 300A Cable 12.95 Ant Amp/Splitter 57.95 UHF to VHF Downverter 99.95 Car Ignition Kill /fla shing light 39.95 Car Window Winders 219.00 Ignition Kill Relay 12.95 PL9/5VA Transformer Ferg 22.95 PL40/5VA Transformer Ferg 22.95 PL15/20VA Transformer Ferg 34.95 PL30/20VA Transformer Ferg 34.95 PL40/20VA Transformer Ferg 34.95 89.95 49.95 14.95 32.95 15.00 3.95 1.00 99.00 9.95 75 .00 95.00 2.00 16.95 3.50 19.95 7.50 5.95 5.95 5.95 5.95 5.95 5.95 89.00 9.95 29.95 39.95 109.00 24.95 2.00 17.50 .40 5.50 .80 145.00 95.00 .80 3.95 3.95 3.95 3.95 3.95 3.95 3.95 4.25 3.95 7.50 7.50 7.50 269.00 59.50 14.95 30.00 15.95 17.95 19.95 19.95 99.00 69.50 59.00 29.95 35.00 29.50 29.95 12.95 3.95 35.00 19.95 10.95 9.95 10.95 3.95 14.95 39.50 7.95 37.95 69.95 27.95 175.00 6.95 10.95 10.95 22.95 22.95 22.95 I I MF1075 MF1078 MF1081 MT2117 NA1006 NL4150 NC4266 NC4267 NC4270 NC4272 PS0356 PS0642 PS0672 PP0841 PS0845 PP0861 PS0866 PA0885 PS0902 PS0903 PP0932 PP0934 PP0936 PP0938 PP0940 PP0945 PP0947 PP0948 PP0950 PP0965 PP0967 PP0968 PP0970 PS0983 PP0992 PP0993 PP0996 PA3504 PA3588 PA3597 PA3650 PA3656 PA3676 PP4022 PS4102 Pl6482 Pl6484 Pl6496 Pl6526 PL6555 Pl6558 PH9225 OM1450 OP5030 QP5054 QP5056 OC7160 RGSOOO RG5001 PG5002 RG5003 R05285 R05286 A05296 SB2504 SY4015 TS1470 TS1477 TSl 494 TS1581 TH1902TH1906 WB2302 WB2304 WH3082 WH3086 XV2060 X04600 XC4720 XC4725 YT2720 YX2930 YT6540 ZRl 160 ZV1625 ZT2185 PL18/60VA Transformer Ferg 47.50 Pl24/60VA Transformer Ferg 47.50 PL30/60VA Transformer Ferg 47.50 40 + 40V 160VA Toroidal 65.00 Protek Moisture Aepellant 6.95 Economical Cable Markers 4.95 PCB Etch ResistER-71 18.95 Developer for Etch Resist 11.95 CopyingFilm125x150x6 17.95 Copying Film 200 x 275 x 2 17.95 7 Pin DIN Line Skt 1.00 F59 Coax Socket 1.40 Twinax Coax Socket 11.95 D825 A/Ang PCB Plug 4.50 DB25 A/Ang PCB Socket 6.95 D37 Male PC vert pins (Pk 10) 2.00 D37 A/Ang PCB Socket 7.95 AS232 Surge Suppressor 19.95 24 Pin Centronics IDC Plug 2.50 24 Pin Centronics IDC Socket 2.50 64 Way PCB C Body Plug 9 65 96 Way PCB CBody Plug 12.50 32 Way PCB CBody Socket 7.50 64 Way PCB CBody Socket 13.95 96 Way PCB CBody Socket 17.50 16 Way IDC Header 2.95 26 Way IDC Header 3.95 34 Way IDC Header 3.95 50 Way IDC Header 4.95 16 Way A/Ang IDC Header 2.95 26Way A/Ang IDC Header 3.95 34 War A/Ang IDC Header 4.95 50 Way A/Ang IDC Header 5.95 14 Way IDC Line Socket 2.00 16 Way IDC Line Socket 1.95 26 Way IDC Line Socket 1.95 50 Way IDC Line Socket 2.95 6.5m Plug/3.5m Socket Adaptor 1.95 6.5m Plug/6.5 Ster Socket Adpt 1.95 6.5 Star Plug/2 x 3.5 Ster Socket 1.95 Pl259 Plug/ RCA Socket Adaptor 3.95 Pl259 SockeVBNC Plug 3.95 Pal Socket/RCA Socket Adaptor 2.50 Travel Adaptor Set 19.95 IEC320 Line Socket/Cord A/Hand 7.95 16 Pin IC Socket Pk 100 19.95 18Pin Socket Pk 100 23.95 22 Pin W/Wrap Machine IC Skt 4.15 24 Pin OIL Header Plug.Cap 4.50 24 Pin DIL IDC Plug/Cover 3.95 40 Pin DIL IDC Plug/Cover 4.95 Batt Holder Button Cell 2.95 HC3500T Digital Multimeter 169.00 VU Meter MU45 16.95 Centre Zero Tuning Meter 9.95 Signal Strength Meter 9.95 Little Professor Texas Ins 29.95 .001 to .002 G.Cap Pk 50 Pcs 7.50 .0027 to .0056 G/Cap Pk 50 Pcs 7.50 .0068 to .015 G/Cap Pk 50 Pcs 7.50 .018 tp .039 G/Cap Pk 50 Pcs 7.50 8mhz X tal 5.50 8.867MHz X' tal 5.50 20 MHz X'tal 5.50 GS Silver Oxide Battery 2.95 48 V 6 PDTRelay 2.95 12 V 15 Watt Soldering Iron 11.50 TipAdcola DesolderPencil 13.95 Adcola S50 240 V Solder Iron 39.95 Tip Scandia Desolderer 8.95 Wire Brushes - Supertool 19.95 Grinding Bits - Supertool 14.95 Teflon Coax 4 mt 10.00 Teflon Coax 10 mt 20.00 3mm Auto Cable Brown 9.2 mt 4.75 3mm Auto Cable White 9.2 mt 4.75 Bosch Rotating Vane 6 Cyl 49.95 Chinon 360K 5.25 Diskdrive 149.00 Verbatim 3.5 in 1S/2D 39.95 Verbatim 5.25 in 1S/2D 22.00 Endless Loop Tape Player 29.95 Smokeless Ashtray 14.95 STD Bar Telephone 34.50 5082- 2800 Schottky Diode 2.60 LM337K 2-30 V Reg 5.95 BCy71PNPT01845 V 200mA .95 35.00 35.00 35.00 45.00 4.50 2.95 9.50 5.95 9.50 9.50 .50 .40 5.95 1.50 1.50 .50 2.00 12.95 1.00 1.00 5.00 6.50 4.50 6.50 9.50 1.50 1.75 1.75 2.00 1.50 1.75 2.00 2.75 .50 1.00 1.00 1.50 1.00 1.00 1.00 2.00 2.00 1.00 13.95 4.95 9.95 9.95 1.00 1.20 1.20 1.95 1.75 129.00 8.50 4.95 4.95 10.00 2.95 2.95 2.95 2.95 2.00 2.50 2.00 1.00 .50 6.95 8.95 30.00 4.00 12.95 8.95 3.00 6 00 Z:75 2.75 39.95 100.00 30 00 17.00 22.50 7.50 19.95 1.00 3.50 .40 ZT2305 ZT2309 I m310 ZT2360 I ZL3061 I ZL3307 ZL3326 I ZL3566 ZL3710 I ZL3756 ZL3762 I ZL3911 ZL3990 ZC4000 ZC4006 ZL4014 ZC4426 ZC4501 ZC4503 ZC4512 ZC4526 ZC4572 ZC4580 ZC4582 ZC4583 ZC4594 ZC4902 ZC4921 ZC4922 ZS5003 ZS5009 ZS5012 ZS5013 ZS5021 ZS5033 ZS5049 ZS507B ZS5092 ZS5095 ZS5017 ZS5122 ZS5126 ZS5147 ZS5148 ZS5155 ZS5156 ZS5158 ZS5160 ZS5162 ZS5166 ZS5173 ZS5174 ZS5190 ZS5191 ZS5194 ZS5195 ZS4196 ZS5243 ZS5258 ZS5266 ZS5365 ZS5368 ZS5629 ZS5802 ZS5837 ZS5854 ZS5894 ZZ8005 ZZ8015 ZZ8020 ZZ8030 ZZ8035 ZZ8040 ZZ8048 ZZ8056 ZZ8063 ZZ8065 ZZ8082 ZZ8195 ZZ8197 ZZ8198 ZZ8416 ZK8822 ZL8843 ZN3442 NPN PWR 140V 10 A ZN3565 ZN3566 ZN5245 TL061 JFET Oo Amp LM307 LM326 NE566 UA709 Round MC1496G CA3028 LM3911 ZN414 Radio IC 4000 CMOS 4006 CMOS 4014 CMOS 4426 CMOS 4501 CMOS 4503 CMOS 4512 CMOS 4526 CMOS 4572 CMOS 4580 CMOS 4582 CMOS 4583 CMOS 40194 74C02 74C221 74C922 74LS03 74LS09 74LS12 74LS13 74LS21 74LS33 74LS49 74LS78 74LS92 74LS95 74LS107 74LS122 74LS126 74LS147 74LS148 74LS155 74LS156 74LS158 74LS160 74LS162 74LS166 74LS173 74LS174 74LS190 74LS191 74LS194 74LS195 74LS196 74LS243 74LS258 74LS266 74LS365 74LS368 74LS629 7402 7437 7454 7495 Z80ACTC Z80AS10 ZBOASI01 280ADMA 280A DART 6502 Microprocessor 6800 CPU 6810 A RAM 6845 CRT Cont 6850 BT-26.MC6880A 81LS95 81LS97 81LS98 4116150ns S-576A Dimmer SAA1027 Motor Drive 5.50 .65 .95 .80 2.45 1.50 5.95 3.45 1.25 4.40 4.50 5.50 2.75 .80 1.35 1.75 2.90 1.95 .95 .80 2.35 1.95 10.50 2.90 1.50 4.75 .60 3.95 9.50 .90 .90 1.00 .80 1.10 1.00 1.00 1.00 1.50 1.45 1.45 1.50 1.20 3.45 3.95 1.85 1.85 1.40 1.40 1.25 1.00 2.20 1.40 1.85 1.85 1.50 1.85 2.95 2.95 1.75 1.25 1.25 1.60 6.50 1.00 .80 .80 .80 6.95 14.95 12.95 14.95 12.50 14.95 4.00 2.50 6.50 7.00 .40 1.40 5.95 3.90 4.95 11.95 15.00 2.00 .20 .20 .20 .80 .50 .50 1.20 .30 1.50 1.50 2.00 1.50 .20 .60 .40 1.20 .40 .20 .20 .80 .50 2.00 1.00 .20 1.00 .20 1.00 2.00 .20 .20 .20 .20 .20 .20 .20 .20 .40 .40 .40 .40 .20 .40 .50 .40 .40 .20 .20 .40 .20 .50 .30 .40 .40 .30 .40 .60 .50 .40 .20 .30 .30 2.00 .30 .30 .30 .20 2.00 4.95 4.95 4.95 2.95 4.95 .50 .20 1.00 2.00 .05 .20 1.00 1.00 2.00 5.95 5.00 v"'"" JI 'JIGS.JA _ . . ONICS 'JICSJA , - ------ - -- - -- - - -- -- - ---- - - -- ----- - - - -- - - - -- --- - --- -- - ---- - ---- _ _ __ _ 'JICSJAYCAR JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS 'JICSJAYCAR JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS 'JICSJAYCAR JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONI CSJAYCAR ELECTRO NICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS 'JICSJAYCAR JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRO NICSJAYCAR ELECTRONICSJAYCAR ELECTRONlCSJAYCAR ELECJRONICS ··-- . - ·- ,.,, ................ ................ ................ ... ................ ...................................... , ...... . ......... . . . . . . . . . . . . . ............... , ........... ,.. . . . ..... . .... ......... ,,..,,.,,.,.,,.., ........................................................ -. - ----- - - JI JI JI JI JI AYCAR ELECTRON1csJAYCAR ELECTRON1cs:i,;.;,c,.,-Fi ELEc-moNics:iAvcAR ELEc i-FioNics:iAvcAR ELEci-FioNicSJAvcAR AYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR AYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR AYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR AYCAR ELECTRONICSJAYCAR AYCAREL ____ _ _,, ___ __,_ __ ELECTRONICSJAYCAR _ , ______ ,, _ __ ___ _ __ ELECTRONICSJAYCAR ___ __ _ __ ___ ____ _ __ ELECTRONICSJAYCAR ___ ___ _ · ·-· - ELECTRON - · - --- - ..ICSJAYCAR __ -- -- · - ELEcrnoNicSJAvcAR ELECTRoN,c~vcA~ ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRON ELECTRONICSJAYCAR - ·-- - - ICSJAYCAR ·- -· · --·----- .. -- Low Noise Universal Pre Amp Kit Power Supply Load Protection Kit Refer Silicon Chip June 90 Ideal for a magnetic cartridge, tape player or microphones. Shortform kit, includes PCB switch, cable and all electronic components. No box,front panel or panel hardware supplied. Refer Silicon Chip June 90 This add-on board prevents dangerous voltages from being delivered to a load by any dual trackng power supply when it is turned on or off. Short form kit. Includes PCB, relay and all specified components. ~"' "o Cat. KC-5077 Ferguson Transformer Bargains VARTA BATTERY MADNESS VARTA 2.4 V 100mA/ H Ni-CAD These batteries are encased in a black plastic housing which measures 30 (L) x 16 (W) x 19 (H) mm. They were removed from printed circuit boards by simply cutting of the PC terminals so to use you would need to break open the plastic case. Inside are two 1.2 V cells. So purchase 4 of these. remove 1 cell and you have an 8.2 V (9V 216 type) battery for only $4. not about $20. Ideal for Hobbyists, experimenters, etc. To buy these today they would cost about $13 ea. PF-4725 A large transformer ideally suited to computer power supplies. Size 115 (L) x 10 (W) x 86 (H) mm. Primary 2 x 120 V 50hz (240 V) 1 x 110V Secondary 16 V Regulated to+ 12V DC 5A 16 V Regulated to -12 V DC 5A 9.3V Regulated to 5 V DC 5. 7A ONLY $1 each 10+ .90~ each 100+ .75~ each Cat. SB-2470 These transformers would normally cost about $80 each. We have a limited quantity available for only $30 each. 5mm 3000 MCD LED An amazing 3000 MCD of brightness in a LED! Lights up red, clearto look at. A bargain at $30 each ONLY $3.95 Cat. MM-2040 Due to huge weight mail order customers add $8 extra to normal P& Pcharges. 10+ $3.85 CatZD-1796 1pF · 9999uF Capacitance Meter Kit PF-4766 Refer Silicon Chip May 90 This attractive 4 digit capacitance meter kit is designed for workshop, laboratory or serious hobbyists. It can measure capacitance from 1pf up to 9999uf in seven ranges with an accuracy of better than+/· 1% +/· 1 digit. Kit is complete with all components required to finish construction. A medium size transformer measuring 96 (L) x 96 (W) x 80 (H) mm. Primary 2 x 120 V 50hz (240 V) 1 x 110V Secondary 10.5V 3A 16V3A Normally $70 each Cat. KC-5075 s109 ::s..~ s. 0~1;a$;0i :~ch ~~~t:1-' Philips Computer Capacitor Bargain. 1 Mail orders add $4 extra P & P. Cat. MM-2045 1 84 Pin PLCC Socket SALE r- Texas brand, save a fortune on normal prices. 15,000uF 40V Can 1-9 10 • 99 100 up Normally about $25 ea Cat. RU-67 14 TURN YOUR SURPLUS STOCK INTO CASH!! THIS LOT ONLY s12.95 ea Jaycar will purchase your surplus stocks of components and equipment. We are continually on the lookout for sources of prime quality merchandise. CALL BRUCE ROUTLEY OR MARK HARRIS NOW ON (02) 747 2022 Guitar Speakers Full range available 10' 65W RMS 12' 65W RMS 12' 100W RMS 12' 200W RMS 15' 150WRMS Cat. Cat. Cat. Cat. Cat. CG-2376 CG-2379 CG-2380 CG-2381 CG-2832 JAYCAR ELECTF JAYCAR ELECTF JAYCAR ELECTF JAYCAR ELECTF JAYCAR ELECTF ,. _,_,~~LECTF $17.95 ~~? Cat. KC-5078 $32.95 $59.50 $59.50 $89.50 $159.00 $129.00 $2.95 ea $2.50 ea $2.00 ea Cat. Pl-6300 10+ $11.50 ea ru----------, High Energy Ignition l tor Cars with Reluctor I Distributors I I High Quality Electricians Pliers Sale Importers distress, your gain! 220mm long, yeHow handles. super high quality. Normal trade price is $35.04 including tax. Cat. TH-1875 I Refer silicon Chip May 90 Designed for cars with Reluctor distributors. this ignition kit I GRAB A PAIR FOR YOUR I transistor. features improved protection for the coil and main switching I TOOL BOX I Kit includes PCB, die cast box and all components to finish ONLYS12.95 I the kit. ;; KC-5076 ls46.95; I I :ARELEC ELEcr~oN1c~ ELECTRONICS ELECTRONICS ELECTRONICS ELECTRO NICS ~, _ _ _ _ _ _ _ _ _ _ :AR ELEC _, , ... .. -- - ••• --•• •-• •., :AR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRON ICSJAYCAR ELECTRONICSJAYCAR ELECTRQNICSJAYCAR :AR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR :AR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ~ E ~~s;~O~!S~~~~s~~ ~~~s;~?~1s~~vc~~ §~~s ~oNI CSJAY~AR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR AR ELE AR ELE AR ELE AR ELE AR ELE AR ELE AR ELE AR ELE AR ELE AR ELE AR ELE AR ELE ARELE AR ELE AR ELE AR ELE ARELE AR ELE AR ELE AR ELE AR ELE AR ELE R ELE AR ELE AR ELE R ELE .R ELE R ELE R ELE R ELE R ELE R ELE R ELE R ELE R ELE R ELE R ELE R ELE R ELE R ELE R ELE R ELE R ELE R ELE R ELE R ELE R ELE R ELE• R ELE• R ELE• R ELE• R ELE• R ELE• R ELE• R ELE• RELE< R ELE< R ELE< R ELE< R ELE< R ELEI R ELE< R ELE1 R ELE< R ELEI R ELEI R ELEI RELEI R ELEI R ELE< R ELE< R ELE< R ELE< R ELE< R ELE< RELE< R ELE( R ELE< R ELE( R ELE< I R EL E( \R ELE< \R ELE< \R ELE< \R ELE< \R ELE( \R ELE( \R ELE( \R ELE( \R ELE< \R ELE< \R ELE< \R ELE< \R ELE< I R ELE( \R ELE< I R ELE( 1R ELEC CTRON ~~ - --~,.,~,.•~~~ " ~"" ~ ~v •,, v , , • --~CTRON ELECTRONICSJAYCAR ELECTRONICS JAYCAR ELECTRON ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRON ELECTRONICSJAYCAR ELECTRONICS JAYCAR ELECTRON EL~CTRONICSJAYCAR ELECTRON1c s JAYCAR ELECTRON _ECTl1ONICS-JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS 'Ji _ECTAONICS.JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAV.CAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICS JI _ECTRONICS. JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA¥CAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICS JI _ECTRONICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJA '/CAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICS ,N _ECTRONICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICS ,N _ECTRONICS. Y E CAR T Y AR TRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS .,lc' _ECl _ECT _ECT _ECT _ECT _ECT _ECl _ECTI The 'i1N Mk 6 is a high fidelity woofer utilising a 25mm _ECT 11 _ECT diameter long throw voice coil wound on an aluminium _ECT former and a high compliance suspension with a Incorporates a grey polypropylene cone and a square black _ECTI polyurethane foam roll surround. resulting in excellent frame. Suitable for a two or three way system. _ECT This midrange has a grey polypro~lene cone which matches. linearity at high power. Impedance 8 ohms _ECT It has a square black frame and is a totally sealed unit Power Handling 65 watts nns _ECTI Resonant Freq. 49Hz Impedance 8 ohms Resonant Freq. 39.5Hz _ECT SPL 95dB/lw/0.5m Resonant Freq. 700Hz £CT Freq. range 39.5Hz - 5khz Power Handling 50 watts rms Freq. Response 700 - 13kHz _ECT Sensitivity 96dB/1 w/1 mt Freq. Response 50 - 6kHz _ECT Power Handling 80 watts rms system Voice Coil Dia. 25mm Oms 1.73 _ECT SPL 91d8 OMS 2.317753 Oes 0.52 _ECT Cat. CM-2081 OES 0.5470474 Oto 0.4 _ECT OTS 0.4425861 _ECT Vas 'l2.2 VAS 3.241097 _EC T Vented Enclosure _ECT Cat. CW-2109 Volume 20 litre _ECT fb 52Hz _ECT f3 53Hz _ECT Vent Length _ECT 69mm _ECT Vent Diameter 50mm _ECT Cat CW-2105 _ECT _ECT _ECT _ECT _ECT _ECT _ECT _ECT _ECT _[CT _ECT 12W12· woofer. _ECT medium power, low cost. high quality. 25mm voice coil _ECT wound on aluminium former. Polyurethane foam roll sur_ECT round. _ECT Power Handling 80watl.s RMS _[CT The 12MV is a high power high fidelity woofer utilising a 38mm Freq. Reposnse 27 - 5.000Hz _ECT diameter long throw voice coil wound on an aluminium former _ECT Resonant Freq. 27Hz Update your 8/30 woofers• todayi The old 8/30's handled and high compliance suspension with a polyurethane foam roll _EC T Sensitivity 96d8/1w/1 ml 30 watts these 120 watts nns. No need to buy new _ECT surround. resulting in excellent linearity at very high input OMS 3.386084 cabinets - the BMV mounts in the same hole. High quality _ECT powers. OES 1.1 1888 and high performance woofer for most applications. _ECT Power Handling 150 watts rms OTS 0.8409882 Power Handling 120 watts rms _ECT Resonant Freq. ;;~~Hz VAS 13.38968 Resonant Freq. 31Hz _ECT Freq. Range Cat. CW-2122 _ECT Freq. Range fo - 4kHz Sensitivity .ECT Voice Coil Dia. 38mm :sgrams Magnet Weight _ECT Magnet Weight 510 gra,.,m,,., s c=-=c - - - - = - - - - - - - , Oms _ECT 3.7s Oms 1.73 Oes 0.58 _ECT Oes 0.47 • _ECT Oto 0.49 _ECT ato Vas 580L _ECT Cat. CW-2125 _ECT _ECT _ECT _ECT .ECT _ECT _ECT _ECT _ECT _ECT _ECT f _ECl .•... _ECT _ECT _ECT High quality headphone/microphone set. Supplied with a pair of _ECT 32 ohm quality dynamic headphones and a noise cancelling _ECT The Code-A-Phone is a top quality remote control answering machine which is simple to use. It features Digital Recording electret microphone. Insert is mounted on a flexible boom with £CT whereby your voice is recorded on a microchip. windscreen. Supplied with separate stereo 3.5mm plug for _ECT Special features include: h dh d35 I f · rt (M' · rt .ECT • dual recording • personal greeting • call screening • personal memo record • one touch playback • digital message ea p ones an · mm mono p ug or tnse · ,c inse _ECT requires 3-5 volts power _ECT counter • answer only/message limit • ring selector • tape saver • automatic on • fast forward and rewind • easy to for operation. _ECT replace microcassette • expanded message length • REMOTE CONTROL FEATURES: 13 function beeperless remote control This headphone would _ECT • remote on • personal 3 digit security code • fast forward/rewind • greeting change • greeting breakthrough • save easily be worth $50. We .ECT messages • cancel messages • toll saver • last message indicator • full tape retrie11al • repeat playback • personal have a limited quantity _ECT memo - record. available at the absolute _ECT This answering machine has every feature that you will ever require in an answering service. One year warranty. A quality bargain price of $29.95 _ECT od · _ECT pr uct. Cat. AA-20'l2. .ECT Cat. YT-7032 SALE Magnavox SW Woofer 5 Polypropylene Midrange SALE wAss19.95 NOW s12.95 SAVE S7 WAS$42.9 5 Nows2a.95 SAV E s14 SALE Magnavox 12MV SALE WAS s99 50 ~C NOW s59.50 ·..:.;..;.-----~SAVES40 CODE-A-PHONE REMOTE ANSWERING MACH IN E 11a;;u;.. .~EW ....... ;AR .J/-\T\.,1-\/1 C.LCV r=w =A ~S~S-1_1_9- .5 - 0~ SALE NOW s79.50 SAVE s40 wAss59.95 NOW s37_95 SAVEs22 Headphone/Microphone Set ONLY $29.95 s2s9 :AR ELt:\., 1MUl\11\.,.'.:> WAS $39.50 NOW $24.50 SAVEs15 Magnavox · Magnavox 8MV 8/30 Replacement :~g~ SALE 1~1Vl\11•- ~EW >JA YL,AH t.Ct.L.fRONiC'SJh YL;AH tLtt; IHUNl(.;~AYl.,.;AH ~,-, :LECTRON t:.Lt:C I HUN . ' A A LECTRO~ ;AR ELECTRONICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAI l tLtC I HONICSJAYCAR ELECTf1ONICSJAYCAR ELECTRONICSJAYCAR ELECl RONICSJAYCAR ELECTRO~ ;AR ELECTRONICS JAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRON ; AR ELECTRONICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAA ELECTRONICSJAYCAR ELECTRONICSJAYCAR fl ECTRQNICS,IAYCAR El EGIBQNICSJAYCAB..ELECIRONIGS.IAYCAB El ECJBOtJ ---- . . -- . .. ----. -(CAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR (CAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR (CAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR (CAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRO NICSJAYCAR ELECTRO NICSJAYCAR (CAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTR O NICSJA YCAR ELECTRONI CSJAYCAR ELECTRO NI CSJAYCAR (CARELEG ____ ., __ ,.,, •-- · --- - ·--· •. - -· - - - - · .. -· ··-·-- - ---· ·--····-· - - ... --··--. ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRO NICSJAYCAR ELECTRO NICSJAYCAR ·- ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS - JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ' ~ You can save over When buying at Jaycar! The release of several major competitors product catalogues recently enabled us to check our prices against theirs. We were not suprised when on identical items we found we were over 60% cheaper than our competitors on some products. Jaycar has built up an enviable reputation of providing good quality products at very reasonable, realistic prices. We won't be undersold on items of the same quality but, frankly, why bother? Our prices are lower anyway. Jaycar Them % Savings Audio lead 5 Pin Din - 5 Pin Din 4.50 5.95 24% Outdoor Balun 75/300ohm 3.75 5.95 37% TV Set Balun 2.25 3.95 43% Indoor 75ohm Splitter- 2 Way 5.95 7.95 25% Balun Socket -Line 2.25 4.95 55% Burglar Alarm Pressure Mat 19.95 24.95 20% Digital Therm - Body Temp 14.95 19.95 25% Telecom Phone Plug 2.95 4.95 40% Computer Printer Cable 18.95 24.95 24% Freezer Spray (vol may differ) 9.00 22.95 60% Air Duster (vol may differ) 7.95 24.95 68% Desolderwick 2.50 2.95 15% 18m Roll Insulation Tape 1.00 1.95 49% Tweezers - Pointed 1.95 2.95 33% Neon Test Screwdriver 2.75 3.95 30% Pack 300 1/4W Resistors 6.50 9.95 35% Pack 60 Greencaps 7.95 15.95 50% Pack 55 Electrolytics 7.95 15.95 50% Pack 100 5mm Red Leds 15.50 28.95 46% 5600UF 40 V Capacitor 9.50 24.95 62% Pkt 50 PC Pins 1.90 3.95 52% Pkt 25 PC Sockets 3.50 5.95 41 % 75mm Sid Heatsink 6.95 9.95 30% 4' 240 V Fan 24.95 29.95 16% Pkt 4 T03 Insulating Mica/Bush 1.30 1.95 33% T0220 Clip On Heatsink 1.20 1.95 38% T03 Powerfin Heatsink 2.50 3.50 28% Brass Spacers - Clearance 9mm 1.30/8 Pcs 5.50/10 70% Brass Spacers - Clearance 25mm 1.40/4 Pcs 5.50/6 Pcs 62% 5mm LED Mt Bezels 100/20 1.95/15 27% Pkt 4 Big Rubber Feet 1.75 2.50 30% Pkt 8 3AG Fuse Clips 1.20 1.95 38% Cable Joiners - Scotchlok 1.25/4 Pcs 1.25/2 Pcs 50% Metal Box 150 x 76 x 134mm 7.50 9.95 24% Horwod 6' Box 33.95 39.95 15% 25 Pin D Plug 1.95 3.95 50% 25 Pin DIDC Plug 5.95 7.95 25% 9 Pin Din DIDC Plug 4.95 6.95 28% 8 Pin IC Socket .20 .25 20% Multi Turn Trimpots 1.95 2.95 34% SP Bedlamp Switch 1.50 1.95 23% 4 PDT Mini Toggle SW 6.75 13.95 51% Mercury Switch 2.25 4.50 50% Heatshrink Tube 5mm 2.25/1 mt 3.50/1.2mt23% • ' Jaycar Heatshrink Tube 10mm Power Supply 3·6·9-12 V 1 Amp 1.9 AH Gel Battery CSize Nicad Battery 1.2 Ah 555 Timer Applications Book Design of PLC Circuits Book Magazine Binder Budget Disks 5.25 DSDD Pk 10 Budget Disks 3.5 DSDD Pk 10 14 - 16 Pin IC Inserter IC Extractor 8000 UF 75 V CAN BC547, 548,549 PN 100, PN200 2N3055 2732A 555Timer IC Blank SS Fibre/g PCB 300 x 300 3.00il mt 34.95 18.95 6.50 16.95 22.95 7.95 6.50 16.95 8.95 2.95 17.75 .15 .25 2.25 10.95 .70 9.95 4.50/1.2mt20% 39.95 12% 32.95 42% 9.95 35% 24.95 32% 29.95 23% 8.95 11% 9.95 34% 19.95 15% 10.95 18% 3.95 25% 24.95 29% .20 25% .35 28% 2.95 23% 15.95 33% .95 26% 15.95 37% Your chance to save $50 off this great phone. Australian Telephone Distributors Model M~ AUS. Features: - Memory Recall • Pulse/Tone - Redial • Hook Flash - Eavesdrop Alert • Low/Hi Volume A great telephone at a great price. SALE June Only Normally $299 NOW ONLY $249 SAVE $50 Cat. YT-7070 I[ Telephone (02) 74 7 2022 SYDNEY - CITY 117 York St. (02) 267 1614M F'830 530Th 830 S on· n · • · urs · pm • at 9 • 12 355 Church St (Cnr. Victoria Rd)(02) 683 3377 Mon-Fri 9 . 5.30 Thurs 8.30 pm. Sat 9. 4pm 115 Parramatta Rd (02) 745 3077 • Mon-Fri 8.30 - 5.30 - Sat 8.30 • 12 Forest Rd . 121 1021570 7000 Mon-Fri 9. 5.30 Thurs 8.30 pm. Sat 9. 4 : 1 % WATERPROOF CORDLESS PHONE ; ; • ~ , ~~:a~a~Itfa'ifo~dConcord2137 1 Them MAIL ORDERS POST & PACKING P.O.Box185 Concord2137 $10-$24.99 $25 -$49,99 CONCORD HURSTVILLE ~~t~g ~ ~t~g ~ ~t~g ~ ~t~g ff $ 3.75 $ 4.50 ROAD FREIGIIT ANYWHERE 6 50 ~_.. . !: 99 F_A_c_s_1M_1L_E_<o_2_1_1_4_4_0_1_6_7-========~$~o~:,:iR'..!..:.\~~00 ~GORE HILL VISA MAIL ORDER VI ELECTRDr ELECTRDr ELECTRDr ELECTRm ELECTRDr .CTRm ~ ELEC ~ ELEC ~ ELEC 1ELEC 1 ELEC 1 ELEC 1 ELEC 1 ELEC 1 ELEC 1 ELEC 1 ELEC 1 ELEC q ELEC 9 ELEC q ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC RELEC R ELEC >l ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC RELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC 9 ELEC R ELEC q ELEC 9 ELEC R ELEC R ELEC q ELEC RELEC R ELEC R ELEC R ELEC RELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R ELEC R FLEC p ELEC BURANDAQLD MELBOURNE-CITY SPRINGVALE VIC ADELAIDE S.A. ~00 ::::·-='N=A=u=sTRAU=~A:!!!1""=1o=•=a=1 8 188 Pacific Hwy (Cnr. 8ellevue Ave) (02) 439 4799. • Mon-Fri 9- 5.30 Sat9- 4pm 144LoganRd(07)3930777Mon-Fri 9 • 5.30 Thurs 8.30 · Sat 9 • 12 Shop 2, 45 A'Beckett St City (03) 563 2030 Mon-Fri 9. 5.30 Fri B.30. Sat 9. 12 887·889 Spnngva . Ie Roa d MuIgrave I'03·I 547 1022 Nr Cnr. Dandenong Road Mon-Fri 9 - 5.30 Fri 8.30 - Sat 9. 2 100 Wright Street (Cnr Sell7f Street) (08) 231 7355 R ELEC RELEC R ELEC R ELEC R ELEC R ELEC R ELEC A ELEC A ELEC ,JAYCAf'"l!ll!l!ll!l!!!l!!!!!!lll!l!!!l!ll!l■.!!!l!l!l!ll""'l!l!!l!l!l!!!llll!l!!!l!!l!!!!l!ll!llll!ll!l!ll!l~ll!!!llll!l!!!!l!l!ll!!!!l"""l!■. l!"""'!!!!ll""'l!l!■.~lll!l!l!llll!!l"""!!!ll!!l!!!ll!l!■. !!!l!ll!ll!l!lllll!l!!!!IM!!!!!!lonl!-F!l!ri!!l9!!1·1!!5.1!!301!!Fl!ri!!!l81!.301!!!1!-S!!!!al!llt91!!1·1!111!2""'1!1!1!1!!1!!!!1111!11!!1!!111!!!!!11!11!11!1!11!11'10N1 '0NIC1 )JAYCAF.rT..LLV ,._,r'\,, C~ I n v1"1v~,-.. , ..._,,..., , LLL...., 11,v111,._,......,,..,. ,.._,,...., , LL'-'--''' ,v,11vv.Jr\ 1 vr.11 LLL'--', 11v1,,., ..... vvn, 1..1..1..v 11,v1'41v->.1n 1vru~ LLLV I nV1'41VVVr\ IVMn C.LC'v I nU l'lllVU L LLv 111v 1'l1v ,-..1 v/"\n LL ,._, ,JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS ELECTRONICSJAYCAR ELECTRONIC! ,JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS ELECTRONICSJAYCAR ELECTRONIC! ,JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS ELECTRONICSJAYCAR ELECIBONIC1 ~ tAVCAO Cl CCTPO bl!CC" IAYCAD Cl CCTDObllCS IOYCOO C! CCTDOb llCC' \OYCAD Cl C,..T□r'l"'-ILC'~ Cl C{'_T_nn•ucr !Avren.rJ r ,-.Tn.r'\1.11,..C' l ~ _ I ' I r, r-,-,.-r,-.,,... .,. ,....,... C.I Cl"'Tnr'IJ, 11,..C' I AV,..An r-1 ..-,-.-rnru ,, ,-,, Al'IATEUR RADIO By GARRY CHATT, VK2YBX Understanding frequency modulation Despite being one of the most popular modes on the VHF & UHF bands, there are many who are still don't know how FM is generated. So let's take a look at the "nuts 'n bolts" of FM transmissions. The technique of frequency modulating a carrier is usually credited to Major Edwin Armstrong who, during the 1930s, experimented with various methods of reducing the noise that was associated with the reception of AM signals. He discovered that when the frequency of a carrier signal was varied according to the amplitude of the modulating signal, AUDIO AMPLIFIER wide bandwidth required for FM transmission; (2) the fact that best results are achieved using the groundwave mode of propagation (often called "line of sight"); and (3) the problem of phase distortion which occurs when FM signals are bounced off the ionosphere. In fact, operation in the VHF and UHF bands is quite an advantage, as an FM signal can be generated CLIPPER PHASE FILTER MODULATOR MULTIPLIERS PA at low frequency and then multiplied. For example, many crystallocked 2-metre transmitters use a fundamental oscillator at say 12MHz. This signal is then frequency modulated and then frequency multiplied 12 times (normally using two frequency doublers and a tripler) to achieve the output frequency (144MHz). In addition, once at the final frequency, the output stage need not be linear as would be needed for an AM or SSB transmission. Rather, it can be operated in class C for best efficiency. Fig.1 shows a block diagram of a typical FM transmitter. Frequency modulation CRYSTAL OSCILLATOR fig.1: block diagram of an FM transmitter. The signal from the phase modulator is frequency multiplied before it is fed to the power amplifier. a large improvement in received signal to noise ratio was achievable. By making a receiver that was able to respond to frequency and phase changes, but which remained insensitive to changes in amplitude, he was able to devise a mode of transmission with good immunity to noise (particularly impulse noise). This ability of FM (frequency modulation) to produce an excellent (by AM standards) signal to noise ratio, even at low signal levels, has now made it the preferred mode of communication for most utility and amateur operations. FM operations are largely limited to the UHF and VHF bands. There are several reasons for this: (1) the 84 SILICON CHIP (a) CARRIER I\ I\ I\ VV V I\ (b) MODULATING SIGNAL (C) MODULATED CARRIER Fig.2: in an FM signal, the carrier frequency increases during the positive half cycle of the modulating signal & decreases during the negative half cycle. Another major advantage that an FM transmitter has is that, unlike AM where a high level modulator is required (normally using a modulation transformer), it requires very little by way of a modulation stage. Normally two transistors (forming a simple amplifier) and a diode limiter are all that are required. This is due to the fact that as the signal is frequency multiplied, so is the level of modulation, or "deviation" as it is referred to in FM terms. Thus, a 2-metre transmitter requiring 5kHz of deviation at the output frequency only requires 1112th that level at the modulating stage. Because this level of deviation is so small, it is quite easy to make a simple FM modulator using a silicon diode as the active device. As the level of audio applied across the diode varies, so does its capacitance. When the diode forms part of the resonant circuit of an oscillator, the fFequency of oscilla- +1~~~~----,----,------,----,---.-------,--.-----r---r---, +0.81---41-------l---+--+---+--+---+-- -t---+---+--+----1 ffi +0 .6 i:: ~ ...... :5 +0.5 <-----<~.......+- c 6 C :a ~ ... +0.41----+l---+-,r,'----\-t->"'u--~......... +o.31-+-I---Alf---,/l\-------i-£\----+*-+*-::1:a¼4-'"'-:71""~~ C -0.4 ' - - - l - ------l---J.--"""':....::....---.1.._ 0 _ J _ _ - L -_ 7 _,__-'-_...i.....__ 10 _.____J 11 12 MODULATION INDEX (X) Fig.3: how the amplitudes of the carrier and sidebands vary with the modulation index. The first order sidebands are displaced from the carrier by an amount equal to the modulating frequency, the second set by an amount equal to twice the modulating frequency, & so on. tion will vary in direct proportion to the level of audio applied. This certainly simplifies construction of an FM transmitter! We know that it is possible to convey information by modulating a carrier either by varying the amplitude or frequency. It is also possible to modulate the carrier by varying its phase. Frequency and phase modulation are not independent of each other, as the frequency of the carrier cannot be varied without varying the phase. In an FM transmitter, the carrier frequency increases during the positive half cycle of the modulating signal and decreases during the negative half cycle. This change in the carrier frequency is called the deviation and is directly proportional to the instantaneous amplitude of the modulating signal. It therefore follows that the deviation is small when the amplitude of the modulating signal is small, and that maximum deviation occurs when the modulating signal is at a maximum. Fig.2 illustrates the nature of an FM signal. In a phase modulated (PM) signal, the deviation varies with both the instantaneous amplitude and the frequency of the modulating signal. Because the deviation increases with modulating frequency, this means that a PM transmitter has inbuilt pre-emphasis. This is the primary difference between FM and PM - in FM, the deviation is proportional to the instantaneous amplitude of the modulating signal only. A major difference between AM and FM is that an FM signal (and OEVIATION ~ v-1 -l-1 t I I I I I I I + FREQUENCY Fig.4: for slope detection, the carrier is tuned so that it sits on one side of the receiver's selectivity curve. As the signal swings between the deviation limits, it produces an AM output varying between X & Y. also PM signals) produce many sets of sidebands that occur at multiples of the modulating frequency on both sides of the carrier. Hence, an FM signal requires a wider bandwidth than an AM signal. The actual number of sidebands depends on the ratio between the modulating frequency, the frequency deviation and the modulation index. For sinewave modulation, the modulation index is the peak deviation divided by the modulating frequency (in Hz). For example, if a transmitter has a peak deviation of 3kHz either side of the carrier frequency, the modulation index when it is modulated by a sine wave of 1000Hz will be 3. If the same transmitter is now modulated by a lO0Hz signal, the modulation index changes to 30. By contrast, in a PM system, the modulation index is constant r egardless of the modulating frequency. In an FM system it varies with the modulating frequency. Also in an FM system, the ratio of the maximum carrier deviation to the highest modulating frequency is called the deviation ratio. Typically, the deviation ratio for commercial and amateur equipment operating at 5kHz deviation and with modulation limited to 3000Hz is 1.57. Fig.3 shows how the amplitudes of the carrier and sidebands vary with the modulation index. Assuming single sinewave modulation, the first order sidebands are displaced from the carrier by an amount equal to the modulating frequency, the second set is displaced by an amount equalling twice the modulating frequency, and so on. So it can be seen that the amplitude of the sidebands is dependent on the modulation index and not the amount of deviation. In addition, the carrier strength varies with the modulation index, unlike an AM signal where the carrier amplitude remains constant and the sidebands vary. At a modulation index of 2.405, the carrier disappears and at a higher index the phase is reversed, the energy being transferred from the carrier to the sidebands. However, the total power of the JUNE 1990 85 AMATEUR RADIO - UNDERSTANDING FM Vee Fig.5: block diagram of Motorola's MC3357 narrowband FM IC. It includes an oscillator, mixer, limiting amplifier, demodulator, active filter, squelch, scan control & mute switch all on one chip. signal remains the same, regardless of the value of the modulation index. This is why it is possible to use an inexpensive amplifier in the PA stage of an FM transmitter, as the amplifier does not need to be linear. Receiving FM & PM The reception of FM and PM signals requires a different type of receiver compared to that used in the reception of AM signals. First, the detector must be able to convert the incoming FM information 'into AM information. While FM signals can be received on an AM receiver (and vice versa), the results are unsatisfactory due to the high level of FROM IF AMPLIFIER ,- - -----, T1 distortion caused by the selectivity of the receiver. Fig.4 shows this effect. Hence an FM receiver must have a wideband IF filter. It must also have a limiter stage added between the last IF amplifier and the detector. This limiter is actually an overdriven amplifier. It is driven into clipping so that the output is at a constant level, regardless of input signal. As a typical input signal to a receiver can be in the order of fractions of a microvolt, it is necessary to have a significant amount of gain (often 50-60dB) before the limiter. This often requires six or eight cascaded stages of gain to ensure 01 1N34A 0.1 I I I I I I I I I I 100pF .001 I L_ RFC B+ 02 1N34A AUDIO GAIN VR1 500k .,. Fig.6: a practical FM disciminator circuit. Any shift in the frequency of the input signal causes a phase shift in the voltage components of the transformer secondary. These voltage components are then rectified and constitute the audio output. 86 SILICON CHIP stability. Each stage of gain must have a different time constant, with each stage limiting the range of signals passed by the previous stage. Fig.5 shows the block diagram of the MC3357 IC which is a complete FM limiter and discriminator. Note the limiter amplifier stage. Fig.6 shows a practical discriminator. The voltage induced in the transformer secondary is 90° out of phase with the input signal. As can be seen, the input signal is capacitively coupled to the secondary of the transformer. The secondary voltages appear so that one side leads the input signal, while the other side lags by an equal amount. When rectified, these signals cancel each other and produce zero voltage at the output. However, any shift in the frequency of the input signal will cause a phase shift in the secondary voltages at either end of the winding. The varying voltages (one increasing in output and the other decreasing) are then rectified and become the audio output (ie, they no longer cancel out). This output signal is fed to the following stage via a 0. lµF capacitor and 500k!1 pot. Disadvantages Although many consider the performance of an FM receiver to be superior to that of its AM counterpart, largely due to the FM receiver's ability to "capture" the strongest signal and produce a high signal to noise ratio, there is one significant advantage where safety is concerned in using an AM receiver. In an FM receiver, the strongest signal received, even if it is only two or three times stronger than other signals on the same frequency, will be the only signal demodulated. In an AM receiver, an S9 signal can be quite noticeably degraded by an S2 signal on the same frequency. This is one of the reasons why aircraft still use AM transmissions on VHF and UHF (so that it is always possible to hear both stations on the same frequency). This is despite the assumption of most that AM stands for "ancient modulation"! ~ REMOTE CONTROL By BOB YOUNG Design factors for model aircraft This month, we will move on to a design study of a hypothetical R/C aerobatic aircraft. We will examine in detail the various design problems and the aerodynamic, mechanical and computerised options available to overcome these problems. To begin, we must have a clear understanding of the tasks we require the proposed aircraft to perform. Fig.1 shows the current FAI aerobatic schedule which is, as you can see, an awesome task for any aircraft. Compounding the difficulty confronting the model designer is the fact that, in competition flying, every manoeuvre is performed under the scrutiny of the judges. Those wishing to win cannot afford any shortcomings in aircraft design or errors in flying. This is a terribly demanding situation and just as full size motor racing has shaped the cars we drive today, the international aerobatic contest has shaped the models and radio equipment currently in use on club fields. The sad part about all of this is that the average flyer has little need for this level of sophistication but feels left out or deprived if his equipment falls short of this level. Expensive equipment does not make a good flyer. That comes with dedication and practice. Only after you have achieved complete mastery over the basic equipment and it begins to hold you back is it necessary to look for something better. Few ever achieve this level. I know that I certainly never did. It was always my flying ability that let me down. However I digress. Upon careful scrutiny of the F3A flight program, several interesting essentials emerge in relation to the design of our proposed aircraft. (1). The model must fly as straight as an arrow and perform all manoeuvres smoothly. (2). The model must perform all manoeuvres equally well, whether upright or inverted. (3). The model must be able to turn sharply. (4). It must be capable of flying on its side for some distance without loss of altitude. (5). It must be capable of vertical flight for some distance. (6). It must be capable of performing a snap roll. Going back to our basic aerodynamics, we can see that items 3 and 5 are complementary. Both call for a good power to weight ratio. Item 3 calls for a light wing loading as well. Item 4 is a complex issue but speed and power does help, again complementing items 3 & 5. Item 6 is a problem and is included for this very reason. This ·manoeuvre calls for large aileron deflections and is in direct opposition to the smooth flying required for all other manoeuvres. Here we arrive right at the heart of the need for the sophisticated encoders of today. Neutral stability There are two basic approaches to Item 6. One is to design an unstable aircraft that will snap roll with small control deflections. This leaves the pilot with the almost impossible task of flying smoothly in all other manoeuvres. The second is to design a stable aircraft and use large control deflections to overcome this stability. This is the preferred approach. In practise, we use a "neutrally stable" aircraft which is a very good compromise between stability and control. Neutral stability also gives us that "straight as an arrow" flight characteristic. The problem is, however, that while the centring accuracy of the servos is very good, it is not perfect and the large throws amplify this neutralising inaccuracy. Thus, the controls do not centre properly and the aircraft tends to wander, calling for constant corrections in flight. Looseness in the control linkages can add to this problem. Also, the controls become too touchy for normal flying and this shows up as a jerkiness in the flight pattern. Judges frown upon this sort of thing. A second complicating factor is that the aircraft controls are normally more sensitive around neutral and less sensitive as the control deflection is increased. All of this is, of course, precisely what the designers of this schedule had in mind. The old schedule had become too easy. They certainly fixed that. The old pattern was a much nicer, smoother routine. The way we set the controls for that pattern was to set full aileron throw to give the required 3 rolls in the 5 second time limit and full elevator to give the loop diameter required. This JUNE 1990 87 15 t 1 Oow,-nw11\Ct fflCl'I,"' I r LOOP WITH 2 50UAR[ rouR 1/2 ltOllS .,,, SIDEO TSl~Loor J .,_.. - • I I A Y'_ 19 - ~ 17 HUMPI\ BUMP W1Ttl OPTIONS l.,._,....I l 5 ) IMMELMANN MN 9 21 lUOl I I I J 1..- ~-, I J .,,so, ., .,,,,. ., -- .,,. ., .,,,,.;"✓' PROGRAMME St.ALL TURN WITH \ 2X 1/2 IOllu, ,,_ND DOWN ::::::::::::::: Fig.I: the current FAI (Federation Aeronautique Internationale) aerobatic schedule is an awesome task for any model aircraft. Illustration reproduced courtesy Model Aeronatical Association of Australia. resulted in a very smooth aeroplane in flight, with good centring accuracy on the controls. By contrast, the new pattern with its demands for square corners and snap rolls eliminates that approach and · has forced an electronic solution on the aircraft designer. Thus, by introducing a variable rate of control deflection at the transmitter end, it is possible to reduce the control throw to a more acceptable level for the smooth flying sections. The earliest approach tried was the dual rate switch. When activated, this switch gave a reduced rate of throw for full stick deflection; the percentage of travel being adjustable with an associated pot. But..! In effect, we gained little and introduced more complication. The SILCON CHIP ~ /-- F3A FLIGHT 13 HALF SQUARE LOOP WITH FULL ROLL IN VERTICAL I I 88 1/11011 vp, o, 1/4 rolh in bolh lt>gs ,;..,,,-"" centring accuracy remained unchanged because all that dual rate does is to reduce the pulse swing from 1.5 milliseconds ± 0.5ms to 1.5ms ± say 0.25ms. The minimum impulse of the servo remains unchanged. Minimum impulse The minimum impulse is the smallest pulse increment or change the servo can detect. Thus, if this figure is 5 microseconds, we will have 100 steps from centre to full deflection. However, if full stick throw at the Tx only delivers 50% of the servo travel, then we will only have 50 steps from neutral to full deflection. If we now increase the mechanical throw to double the control deflection to make up for the lost electronic movement, we have ef- -- -. .. · · londing zone IC>Oot . Ot 100,,, circl~ .·· ·· ~ ~ fectively doubled the centring inaccuracy. This is an important point to keep in mind when we are discussing ATV (Adjustable Travel Volume). However, the reduced throw on half rate does help make the aircraft a little less touchy. The trade off comes from the fact that there are now two separate sets of aircraft response times to learn - one for high rate and one for low rate. Flying is a terribly instinctive affair, for when travelling at 160km/h everything depends upon reflex action. There is no time to stop and think. The end result can be people starting outside loops at too low an altitude on low rate and being unable to reach the rate switch in time. The loop diameter is thus too large for the altitude available. This problem applies to all con- to as differential control and is a must on some aircraft. Finally, although the Tx control and servo potentiometers may theoretically be linear ("A" taper), they exhibit some non-linearity which will result in servos moving more in one direction than the other. The end result of all of this can be a most unsatisfactory combination of conflicting factors. Remember, the aircraft must perform as well upright as inverted. This means equal diameter loops, inside and outside; rolls equal in speed, left and right; stall turns and spins equally as precise, left and right. This cannot be achieved if the controls travel up more than down or left more than right. STICK DEFLECTION Mechanical compensation SERVO DEFLECTION Fig.2: servo travel vs. stick deflection for an exponential controller. In this type of controller, the servo travel progressively increases as the stick approaches the limits. trol functions fitted with dual rate and doubles the learning time. Exponential control A more sophisticated approach is to apply an exponential response characteristic to the Tx control stick. Fig.2 plots the servo travel against Tx stick deflection for an exponential controller. Here, the encoder electronics inodify the pulse output according to stick deflection. As can be seen, servo deflection is less per degree of Tx stick deflection around neutral but progressively increases as the Tx stick approaches the limits. This nicely compensates for the natural sensitivity of the aircraft around neutral but leaves the minimum impulse and centring accuracy problems unchanged. It does, however, eliminate the dual response time problem and thus to my mind is eminently more suitable for aircraft than dual rate or linear throw transmitters. Non-linearity But the complications do not end there. Most modern servos have on- ly a rotary output wheel to which the control pushrod is connected. This in itself is a nonlinear device again delivering less throw per degree of deflection as it moves from centre (Fig.3}. The same applies to the control horn - again, this is essentially a rotary device delivering a non-linear output (Fig.4). In fact, the output function of a rotating circle is a sine wave. This means that, at the extremes, there is very little change in throw for large changes in the servo angle. Admittedly, the non-linearity is small below 40° deflection but it is there nonetheless. The above explanation should make it obvious that it is incorrect to trim an aircraft for level flight with the servo arm off the 90° reference point. This will result in unequal control throws and loops or rolls of different diameters and speeds. One point here is that this nonlinearity can be very useful when setting up some controls, particulary ailerons which in some cases require only upwards deflection. This non linearity is referred Once again there are ways which do not rely on electronic gimmickry and we used all of these tricks for many years to good effect. Referring once more to Fig.3, it can be seen thatif the servo is travelling more in say the counter-clockwise direction (CCW) than CW, then by setting the servo neutral some degrees off centre in the CCW direction, we will get a good mechanical compensation for the nonlinearity of the servo electronics. As I said in an earlier column, smooth, accurate flying begins with the setting up of the controls and there are many ways to do this, not all of them electronic. This also has a secondary benefit which we shall soon see. But once again, there is a compounding factor. The aircraft may prefer to turn left rather than right or dive rather than climb. This is usually a result of poor design and may need to be taken into account when setting the control deflections. Now we are beginning to see why designers of radio control equipment are constantly searching for more flexibility in their encoder designs. The microprocessor is ideal in this situation. Computer encoders The modern computer encoder has many features which allow us to compensate for the large number JUN E 1990 89 75' 90" 60' Fig.3: the servo output wheel is itself a nonlinear device which progressively delivers less throw per degree of deflection as it moves away from the centre position. CONTROL SURFACE \ 0 0 0 TO SERVO Fig.4: because it is a rotary device, the servo horn is also a nonlinear device. This means that at the extremes, there is very little change in throw for large changes in servo angle. of non-linearities encountered in rigging an airframe. For example, adjustable travel volume (A TV), in which the travel each side of neutral can be adjusted, is ideal for compensating for non-linearities in the electronics and airframe. Exponential Tx controls are very useful for compensating for the natural sensitivity of aircraft around neutral, and the nonlinearity of the rotary output wheel and servo horn. In fact, using rotary servos without exponential control is quite wrong, even though we did it for years and will continue to do so. I am expressing a purely theoretical viewpoint here. In practice, we somehow manage. In fact, when you consider that we could fly a nice pattern with a reed set in which all we had was neutral and full throw, all of this really is nit-picking. I was just so glad to get a basic no-frills proportional set that even now all of this gingerbread is meaningless to me. I still feel no need for it and continue to fly with a basic no-frills 5-channel set. Endpoint adjustment Endpoint adjustment (EPA) or 90 SILICON CHIP ATV is used for overcoming nonlinearity in the Tx and servo electronics. A separate potentiometer is provided in the Tx to allow each endpoint, CW (clockwise) and CCW (counter clockwise), to be adjusted. Computer encoders use a key entry to set the percentage of throw. Thus, the control deflections can be set precisely equal about the centreline. If required, they can of course be set up unequal to compensate for aircraft control characteristics. This is an extremely important feature and quite safe to use, unlike servo reversing which is potentially hazardous. Once you have set up one aircraft to a Tx, it is really dangerous not to have all subsequent models set up the same way. If you have to reverse one or more controls before flying that second model, you are really tempting fate, especially if one of those controls is the ailerons. One nice thing with the computer encoder over the old balanced voltage types is the fact that some transmitters are fitted with a memory which can be programmed to retain the servo trims and travel directions for each aircraft. Up to six aircraft can be stored in some Tx. This at least avoids accidents involving reversed controls, provided the correct program is selected for the aircraft being flown. Yet the story does not end here. Just buying an expensive set does not solve all of the problems. We have still not dealt with the problem of minimum impulse. This must be dealt with in a more subtle way. Good servos needed First, for aerobatic competition, you must buy high quality servos. These feature ball bearings on the output shaft to minimise bearing slop, minimum backlash gear trains for centring accuracy, coreless motors for low current consumption and short transit times. They also feature very precise electronics which have a good minimum impulse figure. Now we are ready for the real work. To begin, we must now turn to the control geometry. Modern model aircraft are fast and place high loads on the control surfaces, as do modern model cars. Exactly the same considerations apply with regard to control geometry. Control flutter Control flutter can be encountered in almost any model aircraft. This is a situation in which the control surfaces vibrate at an extremely high frequency in resonance with the airflow. The noise is just like a "bullroarer" and I have learned to cringe when I hear it. This is an extremely dangerous problem and can vary in its effects from ripping the teeth off servo gears to tearing the control surface completely off the model. I have landed many a model with controls in shreds after being hit by control flutter. It most commonly affects ailerons but all controls are vulnerable. The cure is very stiff linkages, hinges and horns. Any backlash or slackness in the system will allow this problem to manifest itself. Now we arrive at the real implications of using less than the full servo travel available. Fig.5 illustrates the basic geom- SERVO ARM l J___:-=- MOST RIGIO, LEAST MOVEMENT 'V' OSCILLATING FORCE OF AIR . . .l ARM LEAST RIGID, MOST MOVEMENT Fig.5: maximum rigidity is obtained when one end of the pushrod is close to the servo bearing and the other is on the outside end of the control horn. Carried to extremes, however, this gives an unacceptable reduction in control deflection. HINGE c----------i----------) (a) (b) ELEVATOR SECTION, SENSITIVE NEUTRAL SYMMETRICAL SECTION , SOFT NEUTRAL etry involved. Maximum rigidity is obtained when the pushrod on the servo arm is close to the servo bearing and farthest away on the control horn. The problem here is the reduction of control deflection as we carry this to extremes. Thus some compromise is called for, the essential point being that all available servo travel should be used to achieve maximum control rigidity and accuracy. EPA (end point adjustment) works by reducing the available pulse-width deviation Fig.6(a) shows an elevator section that will be sensitive around neutral but less sensitive at the extremes. By contrast, Fig.6(b) will have a soft neutral but increased effectiveness with increasing deflection. available from the transmitter encoder and thus also reduces the servo travel. As useful as it is, over zealous use of EPA on flying controls will only rob you of system performance and open the way to other nasties. However, EPA really comes into its own on throttle, where the end point adjustment is extremely important. One last point on the problem of control flutter. The full size practice is usually to mass or aerodynamically balance all control sur- RCS Radio Pty Ltd is the only company which manufactures and sells every PCB E, front panel published in SILICON CHIP, ETI and EA. 651 Forest Road, Bexley, NSW 2207 Phone (02) 587 3491 for instant prices faces. In aerodynamic balancing, some surface area is placed in front of the control surface hinge line to provide some damping. Mass balancing calls for the weight of the elevators to be balanced by an equal mass placed in front of the hinge line. Sometimes a combination of both is used . Finally, having gone through all of the above to ensure that we have a nice equally responsive aircraft, we find after take-off that it is a dog: sensitive around neutral and very reluctant to roll in one direction. We land and scratch our head. The other problems must wait until the next few columns but the control sensitivity is bound up in the shape of the flying surface and the control surface itself. Before computer encoders, we used this fact of aerodynamic life to introduce exponential control or vice versa. Fig.6(a) shows the cross section of a tailplane which will be very sensitive around neutral and less sensitive at extremes. Fig.6(b) shows one soft around neutral but with increased effectiveness as deflection increases. There are a lot of factors influencing this situation and it is very difficult to design the control response predictably, hence the usefulness of exponential control and the computer encoder. However, when the correct design is arrived at, the aircraft becomes very pleasant to fly. I had one aeroplane that was so accurate on elevator control that altitude could be controlled to within 2cm. This allowed me to land that aeroplane on full throttle on a moderately smooth surface. Some aircraft cannot hold ± 10cm and are very vague to fly. In conclusion, the computer encoder is a very useful tool, but must be used with a studied approach to the problems involved. Used in a casual or lazy manner, it will give no better results than the old encoders. With that we must end for this month. I think I am in big trouble with the Editor. I said I could probably cover aircraft design in three issues. So far we have discussed control deflection; only about 150 more factors to go! ~ JUNE 1990 91 FAX SWITCH Now you can buy absolute top quality disks that are also the che-.pest in Australia! They even come with a lifetime warranty. which Indicates the quality of these disks. So why pay 2·3 times the price tor the same quality? Packs of 10, 0 /S 0 /0 w ithout boxes. or brand name, just their whllepaper Jacket, and lndH label . 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Standard persistence LX-400 .. . L0 -400 .. . LX -850 .. . l 0 •8SO .. . LQ. 1050 ..... . NX\000 .. . SUPE R S KXP 1081 ... . PANA SO NIC 24 PI N.. . STAR NX2410 ..... . ...... .. $ 34 9 ... .... $ 59 5 ...... $4 95 .$ 99 5 .... $ 1.29 5 ....... $4 75 ..... S36i ...... .... ..... $77 5 ..$9 70 pho ■phor . Active DI splay Area : 240mm x 180mm 4 PORT SERIAL .............. $89 VGA 256K .......................$299 VGA 512K ... .................... $399 Ra ■otutlon : 64 Colour:720dots(H) x 350 lines 16 Colour:640dots(H) x 200 lines X14527 .. ... .. .... .. ........ $595 BABY AT* COMPATIBLE COMPUTER! 2M/B RAM $1 ,695 • Final assembling and testing in Australia! • 4 M/Byte Main Board. 2 M/Byte fitted • Swltchable 8/10/12 MHz • 1.2 M/Byte Floppy Disk Drive • 80286 CPU • Colour Graphics Display Card • 8 Slots • Floppy & Hard Disk Controller • Printer Card and RS232 • Keyboard • 200W Power Supply • Manual • 6 Months Warranty • Size: 360(W) x 175(H) x 405(D)mm With 20 M/Byte Hard Disk .$1 ,995 With 40 M/Byte V.C. H.D .... $2,195 With 80 M/Byte Hard Disk.$2.795 ,..,. .... :e, ~ RS232 WIRING ADAPTOR BOX • • • • Male to fem ale 25 De tach able plug on le ad s 2 m1n1Jumper s !dea l for experim enting o r te mporary connectio ns Cat X t 5665 Only $19.95 ® ,-v----·-. CAR ANTENNA BOOSTER • In-l ine 1nstala tion • 12V boOSIS 100" ,, CRYSTAL LOCKED WIRELESS MICROPHONE PANEL METERS AND RECIEVER MtCROPHONE SPECIFICATIONS : GALORE! Dimensions : 115 x 32 x 44 mm Weight : 220 ~ram s R.R .P. $113 Our price, $99 $7.95 Cat A t2073 WIRE WRAP IC SOCKETS We have a grea t range of panel m eters al great pnces I Cat.No. 0.acriptlon Pric e O t OSOO M U45 0 •1 mA 12 50 0 10502 MU45 5Q. Q/50uA 12 50 0 10504 MU4 5 0·1 00uA 12 50 0 10510 M U450·5A 1250 01 05 18 M U45 0 · 1A 12 50 01 0 520 MU450- 1A 1250 RECIEVEA SPEC IFICATIONS : 010525 MU45 0 •20 V t 2 50 Recieving Freq : 37 1 MHz 0 10530 MU52E 0- 1A U 50. Output Level : 30mV (m axim um ) 010533 M U 52E 0 · 5A 14 50 Recievlng System : Su,er 0 10535 M U45 vu PMelre 14 95 heterodyne crystal o sc1llal1on 010538 M U65 0· 50u A 16 95 Powe r Suppl y : 9V Banery o r 9V DC 010540 MU65 0- lmA 1695 power adapter 0 10550 MU65 0- 1OOuA 16 95 Volume control 010560 MlJ65 0· 20V 16 95 Tuning LEO Transmitting Frequency : 37 1MHz Transmitting System : crystal o sc11Jahon Microphone : Eleci ret cor1denser Power Supply : 9V banery qange: 300 feet In open held Dimension s : 185 x 2 7 x 38m m .,eight : 160 grams · C al A 10452 I. •' TOGGLE SWITCHES Cc11 No ULTRASONIC TRANSDUCERS CHROME LEO BEZELS 9mm hole ava ilable 3 colours C ;:1 1 No De scnphon Price ~ 14030 Aed $1 .20 S '4 032G ,een $1.45 S 14034 Ye llo w $1 .45 ~ HEATSINK COMPOUND Heat s1nk compound 1s applied :o !he base a nd mo unting studs o f tr ans1s.1or s and d iode s h mainta ins a positive heatsrnk seal Iha! impro ve s heat tran sfer trom The d evice to the heatsmk thus 1ncreasmg overall ett1c1ency Cat H 118001109 1 Cat H 118 10i150q 1 $2.00 $14.95 s1,010 s · •020 [~~ '1 ~~~r~;i;:~a~t~oik~ zz (L 19991) with up to 20V I/P on the transmIner These units can·t be heard and so are Ideal tor TV remo1e controls , water level detectors . burgalar alarms , motion detectors and 1nformat1on carriers as they c an be eithe r pulsed or used m the continuous w ave mode Full spec1ficat1ons below to r design ~~~~~~ Input VoHage : 20V rm s Oescnpl SPOT D P DT 1.9 10 • so .80 $1.00 so.90 $1.10 C at X 15663 Mate to Male Cal X 1566 1 Male to Female C al X 15664 Female to F•male Nc,11 n~lly $33 95 $4 .95 Cat L1999t {Aece,ve,i $4 ,95 ~ ~ Ca l . No . Col 1-9 l 10 140 Aed S0.15 11 0 ·, • Gm $0.20 /t 01 4J Vlw $0.20 1,0 ,. ,O,a $0.20 10 · 1 $0.12 $0.15 $0 .15 S0 .15 00 $0.10 $0.12 $0.12 $0 .12 CODE KEYPAD • Telephone lype d1g1 tal keyp ad QUALITY 5mm LEDS • Fou r d1911. changeable code SPECIAL, ONLY $69.95 • MINIATURE BUZZER 5-1 5V While or black Cat. C 15062 1-9 $2.50 RS232 BREAK OUT BO X f\ -.,rnpl., 1,1,iy ,, , rn on1tor, nq HC.,,' i, n ' o,r'.H ,, lf• ,trl ,U · ,.-,• y 1111,-r',1, , . t J(J Wf'lt //1 [)()C.kel '-,I /f' 1o • I ,,, l,1 ' •.,..,hnq •nnn,I nr111ri ,111tl p,1 •, r•,nr ; Cat. No Col. 1·9 1 10 150 Red S0.10 10 • · 0(1 $0 .09 $0 .08 ?• 0•o • G,r $0.15 $0 .12 $0 .10 /t 0 t 5? Vlw $0.15" $0.12 S0.10 t (J ..,1q nn1 po we rP(l l f ().., .i nr1 '--.p,H!->'-, ;1 .1 .., w rl r f ,p .._ +•11 .i t1l1• --. .J ••r, ' 11 tHP,l k f) ll ' U H .1 , I' '- <J! " '' • ·'1 11(Jl,I•• .1nr l p,111 I ,tl l ,/ <ll , 111 'h•, ,l , . · , . . 1,0..,,1,,w.., X1 5700 $94 .95 $2.25 ECONOMY TRANSFORMERS 1. 9 2155 .' -l ()V h 1',V · A c.11 M 1. 1 1')'i 1 0 se 95 S9 95 2156 ;.i-1uv fi • 'iV , 1 A C ;it M 1;.,:~h $ 14 95 S13 95 2840 1 40V qy <· 1 <:,-1 1 M 1.-'8 .10 $5 9 5 S4 95 285 1 ? 4 0\." 1/ hV LT l 'iOrnA C.11 M \/H'i· $5 .95 SS 50 2860 ?40V \ '-,V C 1 .''i(lmA $5 95 $4 9 5 6672 ;.>JQV l'i ]0V IA'. 1p 11,•,! C ,i t Ml hfi/ '. l $1 4.95 $ 13 95 .,....,.,..-.J_II C.t t Ml ? AhO FOOT SWITCHES 1-9 10 · • Momentary or o,, ntt models tn choose lrom • Co,d le ngth ?, me 1, e, • 6 3m m plug A 17000 Mome nt ary o peraho n A 17005 Push ELECTRET MIC INSERTS i 1~h g~~/~~ easy boar d 1nsen1o n 0"1 operaIIon .~ 1 each $19 .95 51 .2 0 11 2 WAY RS232 X19 120 ONLY $49 4 WAY RS232 X191 25 ONLY $59 2 WAY Centronics X19130 ONLY $49 4 WAY Centronics Xt9135 ONLY$59 $6.95 a OB25 CONNECTOR SPECIALS • 1·9 10+ P10884 DE9 P $2.50 $1.90 P 1 088 S 0 ( 9S $2.75 $1.90 P I Q890 0A l5P $ 1.00 $0.80 P10891 OA 155 $1.00 $0.80 $1.90 $2.50 $1 .80 P 1089S DA1 5S $ 2.SO $0.80 P · ogoo O0 2 5r $1.00 $0.80 1-1 1 0901 0 8 25S $1.00 P1Q902 0 8 :?SC $1.00 $0.80 111 0904 0 825P $2.50 $1 .90 P 1 0905 UB255 $ 2.50 $1 .90 PC BOARD HOLDER Bener than an extra pair ol hands' o,,must tor all PC B w o"'C a1 T 12444 $9 .95 -=== -=== -=== ::::: g;;:~ FLASHING LEADS Red . 5mm Z10159 1- 10 $110 10+ $1.00 UTILITY BOXES Plashc boxes with aluminium tops and available in tour sizes Very popu lar !o r pro1ec1s and very ecco nomIc aI 1 H1 010 1 150 x90x5Qmm Hl 0 102 195 x1 13x60m m H 10103 130x68x4 1m m H 10105 83x 54x 28mm HI 0 I 10 120x65x38mm HI Ol 12 12Q x65x38mm 1MeIaI I00 1 $ 3.25 $ 4.50 $ 2.75 $ 1.95 $ 2.95 $ 2.95 9 PIN TO 25 PIN CONNECTOR ADAPTORS $8.95 FREE STANDING , FOLD UP MAGNIFIER An eo:::onom1cally priced hanos lree magn1 t1er lets you take care ot all those tnck•( l ine delatled 1obs so o tien encoun!ered in electro nics or any ot many o ther pracllcat uses such a s ho me work hobbies etc Cat T10020 Norma!ly S14 .95 SPECIAL. ONLY $12 .95 . MOSFET SPECIALS 2SJ49 2SJ56 2SK134 2SK176 1-9 $7.50 $10.00 $6.90 $9.50 10+ $7.00 $9.50 $6.50 $8.90 -8087 CHIPS SPE CIJ::IC ATIO NS Connec to rs : D B:>~ ph.,q or> 8 0m11 • ro bbon cable and DB?~ <, Oc. 1<p1 Ind icato rs . Tncolour LED ,:; rorT fl AD ATS CTS DS A CD re RC O TA 1E 1TC Jumper W1res : ?O !mned Pn11 p,~c es Power : Interfa ce pcw er Enclosure : Blac k h1qti 11.,,.µ,H 1 pla s11c D imensi o ns : 8'> ~ 9'> • ]Ornm 10 , 2¼ " MINI SPEAKERS (57mm) Cat.T 12458 SPECIAL. ONLY $9.95 DATA TRANSFER SWITCHES II you have two or lour compatible devices that need 10 share a lh1rd or 111th then these Ine11 pensIve data 1,ansler swI1cnes w,11 save you the 1Ime and hassle ot constantly cha nging cable s and lead s around • No power requ red • Speed and code lransparent • Two,Four pC>SJh"'.>n ro1a,y SWIIC h on front pariel • Th,ee F,ve Intenace connections on rea, panel • Switch comes standard wItn fe male connector MINIATURE HOBBY VICE QUALITY 3mm LEOS . ~ Descript ion 1-9 10 . pin $1 .50 $1 .40 pin $1.85 $1.70 pin $1 .95 $1.80 0In $1 .95 $1 .80 pin $2.95 $ 2 70 µ 1f"\ S2 .95 $2 70 pi n $3 .95 $3 .50 pIr S3 .9S $3 .50 0In $ 4 .95 ~4.50 • Lever operated sucl Ion grip base tor instant mount ing and ~ab1liry • Mount s on smooth no n-porous surfaces • Ideal tor ho ld ing compone nts ana o lhe r <; ma111hghI o bIect s Only $24.95 cc:::::, • Over 5000 possib le com b1na ho ns • Power co nsumpllon 5mA slandby 50mA alarm • Two sector LED and , arm LEO • Wro ng number loc kout • 12V DC opera1 Ion • Re lay o utpu ! • Pa nic bunon • No rma lly open tamper switch • D1mens1o ns 14 5 x 100 x 37mm • AC P3 compahble C at A 130 14 R.R .P. S79.95 8 14 16 18 20 2? 24 ?11 JO 10W HORN SPEAKERS White durable plashc . 8 ohms Cal C 12010 Normally S11.95 each Bandwidth (kHz) : Transm it 4 O (al 100d8) Receiver 5 O {at 73d8 ) Impedance: Transm it SOO Receiver 5000 Cal L19990(T ransm.ner ) C at .No. P 10579 P10580 P 10 585 P1 058 7 P 10590 P 10 592 P10594 J.'1059b f>105 98 ·<<::··>~);:\;\ ··.-_.{'\ t) :/ CENTRONICS GENDER CHANGERS • Female lo Female • Saves mod1ty1ng or replacing no n-mat ing C en tronics cable s • AH 36 pm s w1red s1ra1ght thro ug h 110d8 mIn Senattlvtty (dB,-../ubar) mln : 65 min These quahly 3 level wire wrap soc ket s are I1n •pla1ed phosphor bronze ·-%►{ The pertecI s0IuI1on I Features gold plaled pins X 15668 0B9 Plug 10 0 8 25 Soc ke1 X 15669 '0 B9 Soc ke! 10 0 B25 Plug ~~': ~~=:rl~:;= ~RM~: 0 --- MAIL ORDER HOTLINE .. 008 335757 • • (TOLLFREEI LOCAL: 543 7877 . .. s Genuine Intel ch ips with manua l and data shNt.f pac ked i n bo xes ! 8087•3 14,nMHZ ) $175 8087 •2 {8MHZ) $265 8087•1 {1 0MHZ ) $395 80287-6 {6MHZ) $295 80287-11 (8MHZ) $395 80287• 10 ( 10MHZ) $495 80387 •16 {1 6MHZ ) $795 8038720 (20MHZ) $895 80387•25 {25MHZ) $1 .095 MEMORY 1-9 10+ 1 M/B 80NS .$24.95 .. $22.95 4164-15 .... $2.95 .. .....$2.75 4164-12 .... $3.95 ....... $3.50 41256-15 .. $7.50 ...... .$7.00 41256-12 .. $8.50 .......$8.00 41256-10 .. $9 .50 ....... $9.00 41256-08 .. $9 .90 .. •.... $9 .50 MIDRANGE HORNS Use these quality. all metal. P1ezo 1weeters !or grea1 top end sound In your band speakers disco sound system . etc Rated at 30 wans AM S In a system the y wi ll handle over 100 warts RMS Two 9'zea to chooN from : Si ze : 4·· 11 10 11'2 Impedance: 8 Ohm s Ratl"9 : 30 wans RM S RNpOn N : 1 5kHl 14 kH z Dlmenak>n1 : 102 x 26 7 x 177m m C al C92082 Normally $49.95 Thi• month only $39.95 Slz1 : 3 x 7 lmpecS,-nce : 8 Ohms Rattng: 30 wans RMS RNpOnN : 2k Hz · 15 kHz Dlmenalona : 76 x 1 77 x 145mm Cat C92084 - t y $29.95 Thi• month only $24.95 1.,,.--.. UNIVERSAL BATTERY CHARGER ANO TESTER Sa ve money on expens,ve bat1er1es w11n this univer sa l oanery charge, Features include meter tester and orovIsIons tor D C AA AAA N button and cell batter ie s 9V afld 6V· 1square type s) Come~ compIe1e w1!h detailed ,nsI1uctIo ns $29.95 Cat M :>3533 I Hi~~Hh 1 ~ NICADS! Save a fortune on expenalv• throw away batteries with theM quellty Nlcad, and Rechargera! Si ze Oesc . 1-9 10 • 100 • AA 450 mA H $2 .95 $2 .75 $2.50 SUPER HORN TWEETER • Req uire s no crossover and handles ,1p 10 1oow 1 • Sens1t1v1tv 1OOd B O 5m • Frequenc.:Y Response 3kH1 •30kH1 • Impedance 8 OH M S • Size 96mm diameter : a1 c1 2 102 No rml!ll Y $ 12.95 SPECIAL, ONLY $9 .95 C 1 0 12 AH 2 AH S9.95 $9.50 $1.15 $9.95 $9.50 $8 .95 GIFT VOUCHER AVAILABLE DISK BOXES r-----------------MULTI-CHIP PROGRAMMER CARD • Model LP·A1 • Module: Multi•Chip • Good for programming • SRAM TEST 6116-62256 • EPROM 8 BIT ICs • 2716-27512. 2716A-27512A, 27012-27012, 27C16•27C512. 2804-5,8064, 28256-52B 13 • EPROM 16 BIT ICs • 271024. 27102 , 27210 • MCS-48 series of ICs • 8741-8750, 8748-8748H , 8749-8749H DISK STORAGE UNITS • 80 x 3 112·· · Lockable C16038 .... ............ ..$16.95 • 40 x 3 1/2 ..• Lockable Benchmark test 15.8 13 • 40 x 3 1/2 ·· ··Eclipse·· C16040 .. ................. .$8.99 • 120 x 3 1/2 ". Lockable Cl 6039 ........ :....... ..$21.95 • 50 x 5 1/4 .. _ Lockable C16025 ......... ... ... ... $14.95 • 100 x 5 1/4 ""Eclipse· C16042 .... ..... ... .... ... .$9.95 • 100 x 5 1/4 ··- Lockable C16020 ... ..... .......... $15.95 12MHz G2 Motherboard without RAM X18305 ................... ......•........................................$295 Include 1 MB RAM with parity X18310 ..................................................................$495 16MHZ O WAIT BABY AT USING G2 CHIPSET 16 MHZ O WAIT HALF SIZE AT USING VLSI CHIPSET • 81 16 MHz Sy&lell\ clock speed • 80286· 16 CPU • 0/1 wait atate RAM Acceaa Selectable • Sockets for 80287 coprocessor • System speed hardware and software selectable • Supports up to 1 MB DIP RAM (8x 44256 + 4 x 41256) or 4 MB SIMM RAM • 2 XT and 4 AT Compatible Expansion slota • Real time clock/ calendar with rechargsble battery back up • On board power Good generator • Size: 8.75 x 8.75 inches • Legal BIOS Land mark SI 21.8 There are different merits for the two 16MHz motherboards . The 16MHz G2 motherboards support hardware EMS and later version will also support shadow RAM. The 16 MHz VLSI motherboard can only support software EMS and do not have shadow RAM but It operates In true zero wait state. Unlike G2 ' or neat motherboard which operates under page mode, there Is no need to adjust page sizes In order to attain maximum speed. The MIDI OS-401 Card is the PC standard MIDI intertace that runs most popular PC music programs for . sequencing, recording, composing, music printing, patch editing , music instruction and many other ,ppllcations. Run all programs designed • for the Roland MPU-401 I I I I I· COMPUTER CASES architecture • Socketed EPROM for easy user replacen•ent • 1/3 length (short) card will fit in any computer accepting standard expansion.card, including laptops • Including "Y" cable, external connector box to transport is unnecessary X18164 ................... $195 ---------- Smell footprint. Features security key switch, 8 alota and mounting accessories. Size: 360(W) x 175(H) x 405(D)mm X11093 .......................... ... ....$99 MINI VACUUM CLEANER Use it to clean: • Computer keyboards • Printers • Video recorders • Computer circuit boards C21087 ................. $12.95 TOWER COMPUTER CASING Remount your computer to give it that professional look . • Accepts XT. AT. Baby AT and 386 boards • Horizontal full height hard disk drive mounting • Room for 2 x3 112" and 2 x 5 114'" floppy drives • Full height HOD plus fan mount • Size : 165(W) x 600(H) x 500(0) X11105 ..................... $249 ~ ot-lL'< ~ MICROSOFT' COMPATIBLE' • Auto-selection and autotransfer between mouse system system PC mouse mode and Microsoft serial mouse mode • Microsoft Serial Mouse and Mouse System compatible • Super high tracking speed : 600mmi sec • Super high resolution: 200 D.P.I. (0.12mm/dot) • Silicon rubber coated ball • Optical rotary encoder X19952 .......... ....... . $89 EXTERNAL PS/2* COMPATIBLE 5 1/4" DISK DRIVES • External 37 pin connector • Internal 40 pin adaptor cable for PS/2 models • 40 pin card edge • Installation Gulde C11907 ........ .. ........... $245 WAS $450 MAGIC STAGE A wor1<ing bench for your Mouse. •High quality ABS plastic and anti-static rubberised top •Stationary holder ·Includes pull-out shelf for Mouse •Dimensions: 280 x 260 x 25mm • Fits over keyboard C21080 .... ............. $22.95 COPY HOLDER (YU -H32) · Adjustable arms allows easy positioning • Copy area 9 1/2" x 11" • Sliding line guide • Clamp mounting - ~ 18 16MHz VLSI Motherboard without RAM X18325 ..........•.....•.•..••.........•.•...........•.•..........•.•••.$395 Include 1 MB RAM with parity X18330 ................................................................. $595 fillJjj BABY AT* STYLE COMPUTER CASE • 8116MHz System Clock Speed • 80286-16 CPU • Page interleave Memory management • Hardware Implementation of LIM EMS4.0 • Socketa for 80287 Coprocessor • Optional Independent Cl ock for 80287 Coprocessor • System speed Hardware & software selectable • Supporta up to 1MB DIP RAM (8 x 44256 + 4 x 41256) or 4MB SIMM RAM •2 XT and 4 AT Compatible Expansion slots • Real time dock/ calendar with Rechargsble battery back up • On board power good g-ator • Size: 8. 75 x 8. 75 inches • Legal blaa Landmark SI Benchmark test 20.8 17.6 16 MHz G2 Motherboard without RAM X18315 .................................................................$495 Includes 1 MB RAM with parity X18320 .................................................................$695 X18020 .... ...... Only $575 MIDI INTERFACE CARD - DS/401 Cl 6035 ........ ... ... .... $14.95 Description: • 6.25 / 12.Smhz ayatem clock speed • 12mhz version- 80287• 10 CPU • Sockets for 80287 coproceuor • Optional Independent clock for 80287 • Systems speed hardware & aoftwere selectable • Supports up to 1 MB DIP (8 x 44256 + 4 x 41256) or 4MB SIMM RAM Capacity • 2 XT end 4 AT Compatible Expansion slots • Real time dock/ calender with rechergable battery back- up • Ouadtel Legal biu • Size: 8. 75 x 8.75 Inches Land mark SI • MCS-51 series of ICs. 8751-8752 C21062 ....... ........... $29.95 • Three buttons, user oeunau1t= • Silicone coatecj steel ball • High resolution movement of 195 dots/inch. Smaller table space and less hand movement required GRIP CLIP COPY • Optical rotary encoder • Max. tracking speed: 200mi sec HOLDER ••Mouse resident firmware · Attaches to the top of your monitor • Size : 116 x 66 x 34mm • Put your copy right where you • Mouse Driver Software need it spring clip to hold included . allowing you to paper install with all popular software packages. Also included is the • Velcro et mount for easy remova l handy Pop-up menu software C21065 ....... ... .... .... $12.95 that allows the user to integrate the mouse with the keyboard . DOS, and other popular software packages tfo.,..n. / ~~(l r ----------, ~~~ I . ENCLOSED PRINTER STAND • Transparent cover maKes 11 easy to check on paper supply • Paper can be fed from the centre or the rear according to the design of the printer • Remov able drawer which allows paper to be changed without mov ing the printer • Retractable rear basket makes print•out collection fast and convenient • Suitable tor maost printers I 386SX 16MHz MOTHERBOARD Processor: 80386SX·16MHz (0/1 wait state) • Co•processor:80387SX•16 (optional) • CHIPS & TECH NEAT chipsets (SMT) Surface Mount Technology for chipsets & CPU • Supports up to 2MB on board, (Sixteen 44256 and Eight 41256 sockets) Three 8 BIT slots • Five 16 BIT slots • Memory Expansion Slot Optional 2-BMB memory card I. I I I. I • Supports LOTUS-INTEL· MICROSOFT (LIM) Expanded Memory Spee. (EMS) version 4.0 • Supports Page Interleave Mode using 100NS DRAM • BIOS: AMI or PHOENIX • Turbo Light and Hardware Reset connector • Keyboard or Hardware Reset connector • Power Good Signal on board • Baby size main board I I I ' • ._ ________ .... 1· ' I I X18094 ................... $900 C21055 ................. $29.95 THE BUTTON SPIKE PROTECTOR Simply plug the bulton Into an outlet and it will protect all equipment plugged Into adjacent outleta on the a■me branch circuit. SPECIFICATIONS: Voltage: 240V Nominal Total Energy Rating: 150 joulea Response Time: 10ns Protection Level: 350V peak X10087 .................. $39.95 QUALITY JAPANESE DRIVES !' 5¼ " SOOK DRIVE • 360K formatted • IBM " xr · co mpa 11ble Ca t. C11901 fiiiii, APPLE * COMPATIBLE SLIMLINE DISK DRIVE Compatible with Apple 2 • Cat. X19901 . Only $179 FREE PACK OF SIS DISKS WITH EACH DRIVE! APPLE* IIC COMPATIBLE DISK DRIVE !including cable only $189 FREE PACK OF SIS DISKS · WITH EACH DRIVE! · Aoo 1~ 1!', a 1eq+s1ered tr ade man,, Increase the performance of you sluggish XT• approximately lour times with this super fast motherboard. • 8088-2 running at 10 MHz, no wait state • Turbo/ Normal selectable • 640K • 8 Expansion slots • 4 Channel OMA • Keyboard port Excluding RAM X18032 ..................... $179 Including RAM X18033 ..................... $350 Pinpointing component problems In IBM• compatible motherboards can take hOurs. Usually the whole system has to be working to Isolate the troubled area. But not so with the new Postcard Diagnostic Module. So no other cards are necessary to test a bare motherboard. "It now only takes seconds." Slmpllfled debugging for: • Field service- for on-site repairs or maintenance depot work • Manufacturing test- for burn In test flaws and to do quality control • Inspection- Postcard simplifies Incoming and outgoing test processes on stand X18048 ...................... $849 5¼" 1 2 M/BYTE DRIVE • 720K forma tl ed • IB M· AT " compa tible Cat.C 11906 $225 3½ " 1 M/BYTE DRIVE • 720K forma tte d • Double sided double densi ty • 5 1 ,1 mounted Cat. C11909 .. ... .... $269 3½" 2 M/BYTE DRIVE • i 44 M Byte tormaned • Double sided double density • 5 1 -1 mounled Cc1t C11911 .... $299 • 6/12 MHz system clock with zero wait state. 12 MHz, 1 wait state • 80286-12 Microprocessor • Hardware and software switch able • Socket for 80287 numeric data co-processor • 64K ROM • Phoenix BIOS or Award • 8 Expansion slots 386 MAIN BOARD • Intel 80386 CPU (20 MHz) • Socket for 80387 Math co· processor • 32 bit Memory BUS system • Built-In speaker attachment • Battery backup for CMOS configuration table and real time clock • Keyboard controller and attachment • 7 Channel OMA • 16 Level Interrupts • 3 Programmable timers • 8 System expansion 1/0 slots: 5 with a 36 pin and a 62 pin expansion slots I 2 with only the 62 pin expansion slot / 1 with two 62 pin expansion slots (32 bit BUS) Without RAM X18103 .................. $1, 195 Including 2 M/Byte RAM X18107 ..................$1,625 CLICK SURGE BUSTER 6 PROTECTED POWER OUTLETS Ideal for protecting personal computers, video equipment, colour TVs, amplifiers, tuners, graphic equalisers, CD players ate SPECIFICATIONS : • Electrical rating: 240V AC, 50Hz, 10A • 3 x Metal Oxide Varistors (MOV) • Maximum clamping Voltage : each MOV: 71 O volts at 50 amps • Response time: Lesa than ~5 Nanoseconds. X10086 .................... $69.95 BABY AT* MOTHERBOA RD Excluding Ram X18202 ..................... $375 Including 2M/Byte Ram X18201 .....................$795 POSTCARD DIAGNOSTIC MODULE $175 20 M/BYTE HARD DISK 386 TOWER PC • IBM• compatible . 18 msec access, ESDI , 3 month warranty The 386 Tower PC Is a high performance system that's IBM• AT" compatible. However, the 386 Tower PC gives you 2·5 times the performance . FEATURES : • Intel 80386· 16MHz microprocessor • Switchable 16/20 MHz • 2 M/Byte fitted. Total memory expandable up to 16 M/ Byle • Up to 2 M/Byle or 8 M/Byle • Option for 80287 & 80387 co• processor socket • Chips and Technology chip set • AMI Phoenix 386 BIOS • 50 M/Byle hard disk. 42 MtByle formatted . Fast access • EGA card • 3 1/2" drive 1.44 M/Byte Without controller.$2.995 X20070 ..................$5,995 . Drive with controller card . IBM· compatible, 3 month warranty X20010 ..... ........only $499 40 M/BYTE VOICE COIL HARD DISK • IBM· compatible . 28 msec access, 3 monJh warranty Without controller... $895 80 M/BYTE VOICE COIL HARD DISK • IBM• compatible, 25 msec access, 3 month warranty Without controller.$1,495 330 MtBYTE VOICE COIL HARD DISK 286 NEAT MOTHERBOARD • Processor: 80286-12, -16MHz or -20MHz (0/1 wait state) • Co•processor: 80287 (optional) • CHIPS & TECH NEAT chlpsets • 1•4MB dual RAM socket • 1•4MB module RAM socket on board • 640KB-384KB memory relocation • Three 8 BIT expansion slots • Five 16 BIT expansion slots • Memory expansion to 8MB • Supports EMS 4.0 • Page Interleave Technology • BIOS : AMI or PHOENIX • Hardware and keyboard switchable Clock Speed • LED speed display • Power Good Signal on board • Baby size main board • 16MHz X18090 ....... ............. $695 • 20MHz X18092 .................... $895 This card is designed for the IBM• PC/AT" expansion slot and includes data buffering and address selection. The wire wrap area features plated through holes. Extremely useful for R&D, it's address range is 0280H to 72 F7H. + •5V, + ·12V fuse protection and has location for D type 37 pin or D type 25 pin connector. H19125 ....................... $99 FOR GREAT SAVINGS ...... .. GOTO :r :1:e· ROD IRVING ELECTRONICS All sales tax exempt orders and wholesale inquiries to : SYDNEY: 74 Parramatta Rd . Stanmore 2048 Phone : (02) 51 9 3 134 Fax: (02 ) 5 19 3868 MELBOURNE : 48 A'Beckett St Pho ne : (03) 663 6 151 NORTHCOTE : 425 High St. Pho ne : (03) 489 8866 MAI L ORDER & CORRESPONDENCE : P O. Box 620 . C LAYTON 31 68 Order Hotline : 008 33 5757 (Toll fre e. strictly orders only ) Inqu iries : (03) 543 7877 Tel ex : AA 151938 Fa x (03 ) 543 2648 RITRONICS WHOLESA LE : 56 Renver Road , Clayton . Phone :(03 ) 543 2 166 (3 lines) Fax: (03 ) 543 2648 ORDER HOTLINE 008 33 5757 (TOLL FREE) STRI CTLY O RDERS ONLY LOC A L ORDERS & INQUIRES (03) 543 78TT POSTAGE RATES : $1 • $9.99 .. ...... ....... ..... ... $3.00 $10 • $24.99 ... .... ... ... .... .. $3.50 $25 • $49.99 .... .. ... ..•.. ..... $4.50 $50 • $99.99 ... ... ........ .... $6.00 $ 100 + .... . .. .. ... .. .. .. ... . .. .. . FREE The above postage rates are for basic postage only. Road Freight . bulky and frag ile ,terns will be charged at different rates. Errors.and omissions excepted . Prices and specifications subject to change. IBM· PC' XT" AT" are reg,ste, 00 trademan,,s or tn 1erna1•ona1 Bu,,ness Macnm8s · Apple ,s a 1e g,s ta1e d 1tadema,1,, Tellon · ,s a reg ,s1 1re a 1rad ama1 i. 01 Ouporl! · oenon tes r eg ,s tered lrademarkSO! lheu respeci,ve owners I PRODUCT SHOWCASE I an event counter. Drawing only lOµA, it is ideal for battery powered equipment and for use in mobile phones. The in-built event counter can handle up to 1 million events and has an on-chip 256-byte static RAM for the retention of data in the event of the supply voltage falling below 1 volt. For more information, contact Philips Components, 11 Waltham St, Artarmon, NSW 2064 or phone (02) 439 3322. New loudspeakers from Tannoy 300W mono power amplifier Need some extra grunt for your stereo system but don't have the time to build up a kit'? This high power amplifier module could be the answer. It is claimed to deliver up to 300W RMS into a 40 load. All you need do is connect up signal, speaker and power supply leads and you're away. Rated harmonic distortion is less than 0.05 % and the frequency response at 1 watt is quoted as lOkHz to 20kHz without dB limits. Input impedance is 47kn. The unit comes complete with a circuit diagram, parts list, a basic description of how it works and suggestions for the power supply. It is available at $169.50 from your nearest Jaycar Electronics store. New clock timer IC from Philips Philips has just released an 8-pin clock timer IC, the PCF8583 which works as a real-time 12 or 24-hour clock calendar, to keep track of the year, month, day, hour, minute and second. It can function as a real-time clock with alarm functions and as Degaussing wand for TV tubes This handy degaussing wand from J.V. Tuners is the cure for TV tubes which have poor colour purity. The unit is solidly constructed with a laminated steel core and a PVC outer layer, and is double insulated. The supply is 240V AC at 2.2A. The unit comes with instructions on how to degauss TV tubes as well as safety precautions. 96 SILICON CHIP The cost of the unit is $75.00 plus $10.00 post and packaging from J.V. Tuners, 216 Canterbury Rd, Revesby, NSW 2212. Phone (02) 774 1154. Tannoy is back with a dual concentric loudspeaker in their new DC2000 floor standing speaker system. It is a 3-way system with the treble and midrange covered by the 250mm dual concentric driver while the bass is handled by the 250mm woofer. Crossover frequencies are at 400Hz and 2.3kHz. Frequency response is quoted at 44Hz to 25kHz (with no limits). Their nominal impedance is 60 and minimum impedance is 50. Sensitivity is 92db at 1 watt and 1 metre and they are suitable for amplifiers rated at up to 150 watts per channel. The dual concentric driver has a polyolefin copolymer cone which continues the flare of the centrally mounted horn load tweeter. The concentric mounting of tweeter and midrange is claimed to give better stereo imaging. A feature of the DC2000's cabinet is the provision of spikes for mounting on carpet. If you want to sit them on a polished floor, they also come with nylon domes. The DC 2000 system is covered by a 5-year warranty and retails for $1599 a pair. They are available from all Tannoy dealers and selected department stores. Compact 50W power supplies IC insertion tools Now available from Amtex Electronics is the new NFS40 series of switching power supplies. These units can accept inputs between 85-264V AC or 120-373V DC and provide output voltages of 5, 12, 15 and 24V. Their power rating is 50W (with forced air cooling) and 40W with natural air flow. They also regulate down to zero output load. Line regulation is ± 0.5% and efficiency is 70%. For more information, contact Amtex Electronics, 13 Avon Rd, North Ryde, NSW 2113 . Phone (02) 805 0844. High CMRR differential audio line receiver Low cost aviation headset This new aviation headset from Altronics is a bargain compared to established brands. It has a noise cancelling microphone (essential in noisy aircraft cockpits), a cushioned adjustable headband, very soft fluid filled ear surrounds, and the standard jacks for aircraft use. The price is $189.00 from Altronics Distributors Pty Ltd, 17 4 Roe Street, Perth, WA 5000. Mailbag - continued from page 3 preamplifier to one of your major advertisers, in front of a sceptical manager and staff. The initial comparison was with the Studio 200 preamplifier (using the store's CD player, a series 5000 amplifier and Vifa speakers). The difference was not minimal. Two weeks later my preamplifier and modified Studio 200 power of 8V/µs and a 3MHz bandwidth. For more information, contact VSI Electronics Pty Ltd, 16 Dickson Ave, Artarmon, NSW 2064. Phone (02) 439 8622. Precision Monolithics Inc has introduced a new integrated circuit for use in high performance audio systems. Called the SSM 2141, this device is a self contained differential stage line receiver for use in professional and consumer audio equipment such as power amplifiers, mixing consoles and tape recorders. It has the ability to drive 6000 loads so it could also be used as a buffer stage. It has a common mode rejection ratio (CMRR) of lO0dB, typical distortion of 0.02 % when loaded with lO0kn, a typical slew rate limit amplifier were used together in a similar in-store demonstration (using the same equipment as before). Unfortunately, an unmodified Studio 200 power amplifier was not available to pinpoint whether the modified power amplifier was obviously superior or whether the Series 5000 amplifier used was audibly inferior to a standard Studio 200 power amplifier. Alex Kethel Turramurra, NSW These IC insertion tools from Jaycar provide a safe and practical way to install ICs without damaging their pins. Available in a range to suit 8-pin mini-DIP packages right up to the large 40-pin processorsize ICs, these tools have an easy to operate plunger system to push the IC into its socket. The prices start from $7.95 and they are available from any Jaycar Electronics store. ACTIVE SHORT WAVE ANTENNA TECHNIKIT AT4SW (SEE SC JAN '90) t COMPLETE KIT $59 BUILT and TESTED $119 (BATTERIES INC) CASE $10 LOOP ANTENNA Q TECHNIKIT PX1 COMPLETE KIT $44 BUILT and TESTED $69 (SEE SC JUNE 89) Improved signal strength & signal quality in a portable tunable antenna. PACKING & POSTAGE IN AUSTRALIA INCLUDED IN PRICES QUOTED. WRITE OR RING FOR BROCHURES ORDERS ACCEPTED ANYTIME PAYMENTS BY BANKCARD, VISA, MASTERCARD, CHEQUE or MONEYORDER TRADE ENQUIRIES WELCOME JILOA PTY LTD (TECHNIKIT DIVISION) P.O. BOX 73, GLENHUNTL Y, VIC 3163 Phone (03) 571 6303 JUNE 1990 97 Monitor mover arm from Rod Irving The biggest problem with personal computers on desks is that they use up valuable desk space. This clever device from Rod Irving Electronics allows you to position the video monitor anywhere you want for easy viewing and then out of the way when you're not using it. It's clamped to the edge of the Tandy's 1100FD laptop computer desk or table and can support up to 50kg. It is constructed of a sturdy steel frame, has an adjustable height from 3 to 27cm, and the monitor may be tilted by ± 15 ° for convenient viewing. It is priced at $139 and is available from Rod Irving Electronics, 74 Parramatta Rd, Stanmore or 48 A'Beckett St, Clayton, Vic 3168. projection system which uses a 2metre screen. The projection unit can be either floor or ceilingmounted to provide a clearer field of vision. The unit itself has infrared remote control and an in-built 30W stereo amplifier for stereo sound. Also included is a 32-program selection memory and a 99 channel memory. It is multi-standard, able to handle PAL, NTSC or SE CAM format signals. The system retails for $4850 for the projection unit, screen and remote control. For further details, contact Force Electronics, 203 Wright St, Adelaide, SA 5000. Phone (08} 212 5505. TV headphones with volume control The package includes discs with DeskMate and MS-DOS 3.3, as well an MS-DOS reference guide and an 1100 FD owner's manual. The unit retails for around $1700. For further information, contact your local Tandy store. 2-metre projection cinema system This new release from Tandy Electronics weighs just 2.9kgs and measures 307 x 249 x 61mm. It runs MS-DOS 3.3 from ROM as well as a 90,000 word dictionary and DeskMate. The screen measures 122 x 197mm and supports CGA graphics. Included is a real-time clock, parallel and serial ports, and a socket for an optional 2400bps modem. The unit runs off a highcapacity SLA battery and has a full 101-key keyboard. 98 SILICON CHIP In the past, the only way to show a video at a display or meeting or even at a party was via a standard TV. This can severely limit the number of people who can watch at any one time. Enter the new Cine Vision 203 Most stereo TVs and VCRs come with 6.35mm stereo sockets for headphones. The problem is though, some of the pseudo-stereo broadcasts have a tendency to drift out of balance, and very few stereo TVs have balance facilities. These British-made Ross stereo headphones are designed to be used with stereo TVs, having seperate volume controls and a mono/stereo switch. They come with a 5-metre length of cable as well as a 6.35mm to 3.5mm mono converter plug. They're also very comfortable to wear, with a sturdy but lightweight construction. They are available for $59.95 from Amaray Pty Ltd, 1 Johnston Ave, Lane Cove, NSW 2066. Phone (02} 427 3999. ~ The Technology Letters shoulder, offering advice and asking when it would be ready. Those were the rare times I found myself valuable. As for the quiet moments, and there were plenty of those, in the beginning I'd start to do something and one of the assistants would say, "Oh, I intend to do that next week," if it was his area; or "George probably doesn't want you meddling in his territory," if not. The production department is even more of a shambles. The operators call the place "the turnstile"; almost every week, we had a going-away lunch at the pub for somebody. The senior tape operator is a bird who's been there three months. Prior experience: none. She was trained by a school leaver who departed after four months' service. Any technicians? That bird and I didn't get along. Not long after I started, she sauntered into the workshop and said, more or less to the walls, "Is there a technician in the building'?" It was about 2pm. I hadn't been to lunch and was feeling hard put upon, having seen none of the others for two or three hours. "What am I, dog meat'?" was my reply. But I followed her into the equipment area and quickly discovered what dumb mistake she'd made. Even though I didn't crow about it, she was incensed at being caught out. I discovered the engineering department was also responsible for building maintenance. One day, a film editor came in and said he needed a fluorescent tube. I handed him one; he was amazed that I didn't intend to come and replace the thing for him. When George finally appeared that afternoon from his "do-gooder" works, he admonished me for not co-operating. There was another case in the accounts department: a girl with a body like a dream and a personality like your worst nightmare. I heard her rabbiting on about women being equal or superior, until the day she came to demand I remove a ctd from page 79 dead mouse from a cable trench by her desk. "You giving up women's lib'?" I quipped. Mal Content didn't think the comment was funny. He hauled me on the carpet to let me know that "words had been said about my attitude". Mal had an uncanny habit of suddenly appearing in the workshop, just as I'd stopped doing something. I could have been working like a trojan for two or three hours then take a break for a cuppa and in he'd walk. The story you told about the fat furniture salesman - history does repeat itself. The weatherman couldn't seem to get it together, so they decided it was better to tape his segment for the evening newscast. Well, the senior director was having a lot of trouble learning the lurks of the new editing console. One night, he "didn't have time to re-cue the tape" so left the earlier take on the reel. Sure, he told the news director, but the tape operator cued up just past colour bars. Quite a number of viewer calls were recorded that evening; most objected to the four-letter word. Christmas present Fortunately, the ordeal didn't last all that long. Just before Christmas, when I had been there about two months, Mal Content called me into his office. "You don't need to think beyond the probationary period, Dick". "Oh good, my first Christmas present". So he gave me my final cheque and I went back to the flat to pack. Because of other matters, I stayed in town a couple of days more. Just before I went back home, I saw one of the production crew. He said noone had been told that I was no longer working there. Well, I'd had my suspicions confirmed about country television. It was time to head for the big city, to see if matters would improve. I really have to get to work now, Colin. Regards, Richard. 1§;1 Problems? ... and you don't have our NEW 1990/91 148 page electronic parts and accessories catalogue ... Its our latest TRADE catalogue for the consumer ARISTA ... Your one-stop problem solver. ... Stylus ... ...Plugs, Jacks and Sockets ... ... Batteries .. . ...Cable .. . . .. Tools and Technical Aids .. . ... Plug and Power Packs .. . ... Car/Auto Accessories .. . ... Boxed Hi Fi Speakers .. . ...Raw Replacement Speakers ... ... Speaker Accessories ... ... Telephones and Intercom .. . ... Public Address Accessories .. . ... Security and Alarm Accessories .. . ... TV/Video/Antenna Accesories .. . ... Videocam Accessories ... ... Audio Accessories ... .. .Headphones ... ... Computer Accessories .. . ... Microphone Accessories .. . ...Mixers, Amplifiers, Equalizers ... Just about anything you want... Get your catalogue complete with "Recommended Retail Prices" free from your local ARISTA dealer or send $2.50 P & H and your return address to: ARIST~ ELECTRONICS PTY LTD PO BOX 191. LIDCOMBE, NSW, 2141 JUNE 1990 99 ASK SIUCON CHIP Got a technical problem? Can't understand a piece of jargon or some electronic principle? Drop us a line and we'll answer your question. Write to: Ask Silicon Chip, PO Box 139, Collaroy Beach, NSW 2097. Radio alarm for a stock gate I have read with interest the article on the UHF Remote Switch in the December 1989 issue of SILICON CHIP. I have a farm with the main gate acting as a stock gate as well. My problem is that from time to time the gate is left open, allowing stock to escape. I am looking for a circuit I can use so that if the gate is left open a signal can be transmitted to the homestead some 500 metres away, the receiver triggering an alarm. A better system would be to transmit direct to a pocket pager. The transmitter on the gate would have to be powered by a battery and have a range of about 1km. Can you help? Your magazine makes excellent reading for a hobbyist like myself. Congratulations. (T. C., Budgewoi, NSW). • We are inclined to the view that a UHF or VHF link is not the way to go. Rather it would be better to have a link at 27MHz, possibly using a portable CB transceiver as the Calibrating the 1GHz digital frequency transmitter, at the gate, and a standard CB transceiver at the homestead. As you might gather from the suggestion, this means that we have not yet designed a transmitter/receiver link with a range of more than 500 metres. You should be able to pick up secondhand CB gear which will do the job at quite a reasonable price. On the other hand, have you considered a non-electronic solution such as a self-closing gate which can be opened with a nudge from a vehicle (but not by stock)? This would not have the disadvantage of being left open while you are away from the house and therefore unable to correct the situation. Query on directors for TV antennas I have noticed on some commercial yagi TV antennas that the directors on some are insulated from the boom but on others they are not. That goes for VHF and UHF types. And on some, the dipole is and have checked out the multiturn pot. Can you help me? (A. D., Turramurra, NSW). I have just built the 1GHz • We assume that by confirmDigital Frequency Meter project ing the test with a logic probe, featured in the November 1987, you have checked whether or not December 1987 and January the outputs of IC2a are changing 1988 issues of SILICON CHIP. The state. If they do change state, unit seems to work fine (from then the LED is in the wrong way observation) - the range and around. If not, does rotation of function keys and the display all the multiturn pot cause the bias work as described. The first at pins 9 and 10 (ICZb) to vary. If calibration was to solder a shor- not, are the 2.2k0 1 % bias ting link across the lMO input resistors correct? Remember that ICZ (the 10116) pads and put LED1 into the test point for IC2a. Then the is an ECL (emitter coupled logic) multiturn pot had to be adjusted. device and so its output pins will The problem was that with my normally swing between a bout unit the LED does not come on at + 3.25 and + 4.1 V. This means all for the full range of the that if your logic probe runs with multiturn pot. I've also confirm~ TTL or CMOS, it will not show ed the results with a logic probe . the change of state with ECL. 100 SILICON CHIP folded while on others it is not. Can you tell me if this will make a big difference to the performance of the antenna? Also the reflectors on UHF antennas are greater in numbers in one type than other types. Does an increase in the number of reflectors (in an angle) give better results than fewer reflectors? (C. D., Morwell, Vic). • Yagi antennas can be designed to function equally well whether their elements are insulated from the boom or not. This applies to the directors, dipole and reflectors. However, all elements must be made slightly longer if they are not insulated from the boom, because their electrical resonance is changed by this factor. We suspect that there are a number of practical reasons why most commercial Yagi antennas are assembled with insulating elements these days. First and foremost , element mounting blocks moulded from plastic look more attractive and are probably cheaper than mounting brackets fabricated from aluminium. Second, there may be less corrosion (due to the differential aeration effect) with plastic mounting blocks and hence the antenna lasts longer. Generally, antennas which are to be used with 3000 ribbon have their dipole(s) folded while antennas intended for use with 750 coax cable do not. Again, it makes little difference to the overall performance of the antenna since the main effect of folding the dipole is to quadruple its impedance, to match that of ribbon cable. As far as reflectors on UHF antennas are concerned, increasing their number makes only a marginal difference to the overall gain or front-to-back ratio but arranging them in a V-shape behind the dipole is worthwhile as it reduces the vertical acceptance angle. This makes the antenna less prone to ghost signals reflected from aircraft. 01 B0650 F2 7.5A SA + 10000 + 40VW.:r ,J,., 12 IC1 UC3906 Fig.1: this is the 5A version of the SLA battery charger published in the March 1990 issue. Note the use of paralleled transistors (Qt & Q2) to carry the current. You will need to bolt the bridge rectifier, transistors and stud mounting diodes to adequate heatsinks, while the o.rn resistors should be rated at 5W. 13 10 RC 39k 1% 14 .,. RD 560k 1% .039! 0.220 3.6A S1 A---0 F1 1A 01 BYX96-300 240VAC F1 10.9A ~--..-----.--0---.0-0 + + 15A 02 BYX96-300 10000I+ 100D0It 40VW - 40VW 15 TO 12V 60AH BATTERY i- 11 12 RB 15k IC1 398' Fig.2: this circuit uses three paralleled pass transistors and can deliver 10.9A for charging 60 amp-hour batteries. As before, the bridge rectifier, transistors and diodes should be bolted to heatsinks while the o.rn and 0.22fl resistors should all be 5W types. High current variations of the SLA battery charger I want to use a version of your SLA Battery Charger (SILICON CHIP, March 1990) to charge a 24 amphour battery used in a wheelchair. What modifications would be necessary? (R. G., Wagga Wagga, NSW). Can I use the UC3906 SLA battery charger in a circuit for charging batteries up to 60 amp-hour capacity. I want to construct the charger because I have had two batteries fail, probably because I charged them with an ordinary DC 13 1¾ RO 10 560k 1% 14 charger that had no current control devices. (G. S., Elizabeth East, SA). • While we realise we could be setting a precedent here, we have drawn up two variations of the battery charger circuit. Fig.1 is for charging 12 volt 24 amp-hour batteries while Fig.2 is for charging 12-volt 60 amp-hour batteries. The main differences from the circuit described in our March 1990 issue are in the use of multiple Darlington pass transistors to handle the higher current. In both cases, the Darlington transistors are effectively in parallel but have separate emitter resistors to ensure that they share the current load RC 39k 1% equally. Only one Darlington transistor (in each circuit) is controlled by the UC3906, by monitoring the voltage across its emitter resistor. The other differences in the circuit are mainly to do with the specification of much higher rated components to supply and handle the heavier currents. The charger of Fig. l is designed to deliver a maximum current of 5 amps while the circuit of Fig.2 should deliver a maximum current of 10.9 amps. We must emphasise that we have not tried either of these designs on the bench. They are "paper" designs only. Having said that, they should work. JUNE 1990 101 Antenna tuner for communications receiver I am trying to buy an antenna tuning unit specifically designed for shortwave listening that will cover from 500kHz to 30MHz. My receiver is a Kenwood RlOOO and my antenna is a long wire about 300 metres long. Can you help? [W. B., Tenterfield, NSW). • You are fortunate indeed to be able to use such a long antenna. As far as we are aware, there is not a lot to be gained by using an antenna tuning unit to match a long wire antenna to a communications receiver. An ATU is of more use in matching a transmitter [or transceiver) to an antenna, which is important from the point of view of "standing wave ratio" [SWR) and getting the maximum power radiated by the antenna. It will do nothing to increase the gain of any antenna connected to it and thereby will do nothing to improve signal pickup. Power supply needs magic worms Help! I am trying to obtain a circuit diagram for a "Pioneer Magnetronics" 12V 50 amp power supply [Ser. 55159, Type 5D 100-0-3-4N, Model PM 2497 A-2). Actually, I would like a can of magic worms to pour in to get it going but any information I can get would help. These power supplies were originally sold by Ace Electronics in Sydney. Can you help? (J. Bowen, 477 Ebden Street, Albury, NSW 2640}. • We must admit we haven't come across any cans of magic worms just lately although we do seem to come across the ordinary types quite frequently. Can any of our readers give assistance on this one? 24V to 12V converter does not convert I am building the 24V to 12V converter as decribed in the December 1987 issue of SILICON CHIP but am having a little trouble getting it to work. I hope you can assist. The voltage across D9 is only 24V and 102 SILICON CHIP Feedback on the Radfax Decoder I have just finished building the Radfax Decoder from the November 1989 issue of SILICON CHIP. As I encountered a couple of problems, I thought I should make you aware of them. I am an electronics technician by trade and fortunately have access to test equipment for problems. First, there is an error in the component layout on page 22. The 100µF electrolytic capacitor is shown mounted on the board with its polarity reversed. Fortunately, I noticed this before switch-on. The second problem concerns the input to the XR2211. After completion of the project, I couldn't get the LOCK LED to come on. I already have a version of a similar project - described in the July 1985 issue of AEM. Comparing the two units using the same signal from a signal generator, I found that your version required some 2 volts of input signal whereas my original worked with as little as lOmV of signal. The only circuit difference I could see was a 220k0 resistor from pin 2 to common. Removing this solved my problem. IC la oscillates OK. Pins 8, 9 , 10 and 14 of ICl are sitting at approximately ZOV. Any clues? [B. G. , Thebarton, SA). • As you will be aware from looking at the circuit diagram, ICla runs at 40kHz to drive a voltage doubler (Dl, DZ, etc) which generates + 39V. You say that ICla runs but is the + 39V present at the collector of Ql? We expect that it is, for reasons that will become clear in a moment. What appears to be happening is that the circuitry involving IClc, ICl band QZ is not functioning. This means that Q3 is turned on all of the time [rather than on and off at ZOkHz), which is why you have around 20V present at pins 8, 9, 10 and 14 of ICb. You need to check this part of the circuit to see why it is not switching at ZOkHz. Other Fitting a 220k0 resistor in the same position in my original unit destroys its sensitivity also. The data sheets of the XR2211 don't show a resistor used in that location so I have left it out. I don't know if you have other project builders out there wondering why their decoder won't work. I use the record audio output on my Yaesu receiver and the signal level at that point is nowhere as large as that. That said, the SILICON CHIP version of the Radfax Decoder gives the operator more options in its setup, and appears to work better than my original. (J. S., Aitkenvale, Qld). • Yes, the lO0µF capacitor is shown incorrectly oriented on the parts overlay diagram. The 220k0 resistor from pin 2 to common was deliberately included to decrease the sensitivity from lOmV to about ZV. This prevents the circuit from falsely triggering on noise. We recommended driving the decoder from the earphone output of a receiver as the signal levels there are generally higher. Since you are driving the decoder from the record audio output, the sensitivity will need to be increased by removing the 220k0 resistor [as you have done). clues: perhaps D5 or D6 is in the wrong way around or D4 is open circuit. Notes & Errata Radfax Decoder, November 1989: on page 22 , the lO0µF capacito.r at the output of the regulator is shown with reversed polarity on the overlay diagram. VOX With Delay, April 1990: there are three errors on the overlay diagram on page 33. First, the 47k0 resistor shown connected to VRZ should be a 4.7k0 resistor, as shown on the circuit. Second, the lO0µF capacitor located just below IC3 should be a 47µF capacitor [although this value is not critical). Finally, the 47 µF capacitor located just above IC4 should be a 4.7µF capacitor. ~ CEN Cash in your surplus gear. Advertise it here in Silicon Chip. CLASSIFIED ADVERTISING COUPON Advertising rates for this page: Classified ads - $7 .00 for up to 15 words plus 40 cents for each additional word; Display ads (casual rate) - $20 per column centimetre (max. 10cm). Closing date: five weeks prior to month of sale. If you use a PO Box number, you must include your permanent address and phone number for our files. We cannot accept ads submitted without this information. To run your own classified ad, put one word on each of the lines below and send this form with your payment to: Silicon Chip Classifieds, PO Box 139, Collaroy Beach, NSW 2097. PLEASE PRINT EACH WORD SEPARATELY, IN BLOCK LETTERS FUJITSU MEMORY From Japans Largest Manufacturer of Computers the Quality you expect .. SIMM MODULES 1 Mb X 9 sons $115.00 DRAM 1 Mb X 1 sons $10.50 DRAM 256K X 4 SOns $10.50 • Add 20% Sales Tax / $5.00 P & P 2 3 4 5 6 7 8 9 10 11 12 13 14 15 ($7.00) Name ...... .. .. .... ...... . .... ..... ... . . PACIFIC MICROELECTRONICS PTY. LTD. "CENTRAL PARK" UNIT A20, 4 CENTRAL AVENUE, THORNLEIGH N.S.W. 2120 PHONE : 02 481 0065 FAX : 02 484 4460 FUJITSU MICROELECTRONICS PACIFIC ASIA LTD. Street Postcode Suburb/Town Enclosed is my cheque or money order for $ D Bankcard D Visa Card D MasterCard Card No --1._ LI .1..-_L_....J...__.I_ _L__---'--------'--L__--'-- ' - - - ' - --'--- ' ----'--~ Signature ... SATFAX: NOAA, METEOR & GMS weather satellite picture receiving program for IBM XT/AT. Displays in 64 colours. Needs EGA colour monitor & card and "Weather Fax" PC card. $45 plus $3 postage. RADFAX2: HF WEATHER FAX, Morse & RTTY receiving program for IBM XT/AT. Needs CGA, SSB HF, FSK/tone decoder. Also "RF2HERC", "RF2EGA" & "RF2VGA", same as RADFAX2 but suitable for Hercules, EGA & VGA cards respectively . $35 plus $3 postage . FIX-A-KIT $20 PER HOUR LABOUR NO CHARGE FOR KITS THAT CAN'T BE REPAIRED 3 MONTHS WARRANTY ON REPAIRS CONSTRUCTION AVAILABLE HYCAL INSTRUMENTS DESIGN, MANUFACTURE, REPAIR OF ELECTRONIC EQUIPMENT (02) 633 5897 ... ....... or please debit my Card expiry date ..... ../. ...... . All programs are on 5.25-inch or 3.5-inch disc & include full documentation. Only from M. Delahunty, 42 Villiers St, New Farm, Old 4005. Phone (07) 358 2785. BELT KITS FOR VCRs. Please supply brand & model number & $1 2. 00 for each kit required . Prompt dispatch assured. James Cotterill, PO Box 44, Farrer, ACT 2607. SMARTWORK POST-PROCESSOR: if you own a HP? 4 7 5 or compatible flat bed plotter you can plot your own PCBs direct on blank board ready to etch. PP plots 1: 1 and mirror image. Only $99. PC Computers (08) 332 6513. BUILD A LOW-COST 280 microcontroller development system. Uses any PC/XT/ AT/386 or Z80 system as the host computer. Fast PC machine language cross assembler included. Super fast load to target system via MEMORY CHIPS Prices at May 1 st, 1990 Speed Chip type SIMMS 9 X 256 9 x 1Mb (MACS) 8 x 1Mb 9 x 1MbPS2 (IBM) SIPPS 9 X 256 9 x 1Mb 411000 DIP 414256 41256 41464(256) 4164 414256 (1 Mb) ZIP 41256 411000 (1 Mb) 4400 (4Mb) 120ns 100ns Prices (excluding 30.00 34.00 116.00 108.00 165.00 38.00 112.00 10.80 11.40 10.80 11 .80 2.85 3.40 3.40 2.70 3.00 13.50 4.40 12.80 13.20 BOns tax) 36.00 120.00 112.00 40.00 116.00 11 .80 12.20 3.95 3.95 15.00 98.00 sales Tax 20% Uvernlgnt delivery Credit cards welcom,: DISCOUNTS FOR DEALERS Phone for pricing on 70ns, 60ns, Toshiba, Compaq & Laser Printer PELHAM rel (OZ) 421 0011 - Fax (02) 418 6831 parallel printer port; eg, 8K ROM file in 3 seconds on standard 4.77MHz PC. Battery back-up on target system. For more info, send a 41 c stamp to Don McKenzie, 29 Ellesmere Crescent, Tullamarine 3043. LOGIC ANALYSER. Gould Instruments K40 stand alone analyser. Eight nonvolatile memories, ?-inch CRT, 4 x 2K sample memories, 2 x 16-channel, probes up to 100MHz, asynchronous capture. Weighs 7.7kg. $975.00. Import Technologies (07) 372 5138 . TOSHIBA LCD SCREEN. Originally to suit T1 500 desktop. 240 x 180mm, 640 x 200 pixels. Uses 5V supply & JUNE 1990 103 r~---------------------, FREEPOST SUBSCRIPTION COUPON To: Freepost 25, Silicon Chip Publications, PO Box 139 Collaroy Beach, NSW 2097, Australia. NO POST AGE STAMP REQUIRED IN AUSTRALIA. :- i New subscription □ Start in _ _ _ _ _ _ __ Renewal Name _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ (PLEASE PRINT) Street _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Suburb/town _ _ _ _ _ _ _ _ _ _ _ _ _ Postcode_ _ __ 1 year ( 1 2 issues) D $A42 Australia NZ & PNG (airmail) □ Overseas surface mail □ $A62 Overseas airmail D $A 1 20 2 years (24 issues) D $A84 D $A130 D $A130 D $A240 $A65 Enclosed is my cheque/money order for $ _ _ _ _ or please debit my iJ Bankcard Card No. [l Visa Card D MasterCard I'---"---'--~I~I ~I----'--_,__-'-- ] I I I.____.___,_--'-~ Signature __ __ __ __ __ __ L_ ___ ___ _ ___ __ _Card _ _expiry _ _date_~-_____ J r~---------------------, SILICON CHIP BINDERS Yes 1 Please send me _ _ _ _ SILICON CHIP binder(s) at $A 11.95 plus $ A3 p&p each (NZ p&p $A6). Name_ _ __ _ _ _ _ _ __ _ _ _ _ __ _ _ _ _ __ (PLEASE PRINT) Street ___________ _ _ _ _ __ _ _ _ _ _ __ Suburb/town _ __ __ _ _ _ ____ Postcode _ _ _ _ __ Enclosed is my cheque /money order for $ _ _ __ or please debit my i I Bankcard t I Visa Card L l MasterCard Signature _ _ __ _ _ _ _ __ __ Card expiry date _ __,,_ _ L-----------------~-----J TTL drive signals. Suit experimenter. $150 . Import Technologies (07) 372 5138. PUBLIC DOMAIN & shareware software for IBM & compatibles . Catalog disc $4.00 on 5.25-inch 360K or 3.5-inch 720K disc. Also TVREPAIR .TXT which covers faults in most popular brands. It can save hours of work. Just $29 inc. p/post. Martins Television Service, PO Box 1013, Taree, NSW 2430. 104 SILICON CHIP EPSON P80 PORT ABLE battery rechargeable 80-column printer. Serial interface . Very compact & light. 1.1 kg. Uses normal or thermal paper. $175. Import Technologies (07) 372 5138. TOSHIBA T3100 CO-PROCESSOR kit. This piggy-back board enables the fitting of an 8028 7 -8 to the early T31 00 . Two types available, solder in & plug in. Solder version $190 .00. Plug-in version $33q.00 . Import Technologies (07) 372 5138. Advertising Index Adilam Electronics ..... ...... .. . IFC Altronics .............. .... .. .... 46-49 Arista ...... ......... _..... ... ... ...... 99 Board Solutions_ .. __ ......... 58 ,59 David Reid Electronics ... .... ... 39 Dick Smith Electronics ..... 11 -1 7 Electronic Solutions ........ 7 4, 7 5 Elmeasco .. ... ....... .... ....... . OBC Geoff Wood Electronics .. .. .... 69 Harbuch Electronics ........... .. 53 Hycal Instruments ... .. ... ...... 1 03 Jaycar Electronics .... .. .... 26-29 80-83 Jiloa ...... ....... .... .. ...... .. ........ 97 J.V. Tuners .......... ....... ..... ... 53 Oatley Electronics ............... 37 Pacific Microelectronics ... .. . 103 PC Marketplace .. ... .... .. ........ 7 2 Pelham .... ..... .... .... ....... .... . 103 RCS Radio ........ .. .. ...... .. ..... . 91 Resurrection Radio .......... .... 23 Rod Irving Electronics ..... 92-95 Sheridan Electronics ...... .. .... 65 Silicon Chip Binders ......... ... IBC PC Boards Printed circuit boards for SILICON CHIP projects are made by: • Electronic Toy Services , 2/1 11 Glynville Drive, Hackham West , SA 5163 . Phone (08) 382 8919 . • Jemal Products, 5 Forge St, Welshpool, WA 6106 . Phone (09) 350 5555. • Marday Services, PO Box 19-189, Avondale, Auckland, NZ. Phone 88 5730 . • RCS Radio Pty Ltd , 651 Forest Rd, Bexley, NSW 2207. Phone (02) 587 3491 . PROJECT PCBs: ETI-DIGI 1 25 audio amp $9/pair, ETl-1623 IBM PIA card $39 .95 . 6502/Z-80/6800 miniprocessor $49 . PRE-BUil T AUDIO AMPS: 3.5W LM380 $20, LM1875 $30, 150W IC-150 $99, 300W IC-300 $179, 60W Valve-1 $99, 200W Valve-2 $199, Audio ToolkitTool-1 $69, FET-1 super quality stereo preamp $20, Bass & Treble $23. ROBOTICS: experimenter's kit. Includes IBM-PC controller, PSU, stepper motor, manual, software $99. Digital voice recorder TMS-334 7 chips $25. PC Computers, 36 Regent St, Kensington, SA. Phone (08) 332 6513. NO * High quality * Holds up to 14 issues * 80mm internal width * Gold printed with SILICON logo on spine and front cover CHIP These beautifully made binders will protect your copies of SILICON CHIP. We are especially pleased with their look and quality. As soon as the first batch came in, everybody on our staff wanted them to store their own personal issues. You will too. How To ORDER: Phone (02) 979 5644 Fax (02) 979 6503 Made with a distinctive two tone green high-quality vinyl specially selected for SILICON CHIP, and with heavy board covers, each binder holds a year's issues (the 14 issues of Vol. l or the 12 issues of Vol. 2). They will look really smart on your bookshelf. To order your binders, fill in the coupon on page 112 and send it to SILICON CHIP, PO Box 139, Collaroy Beach, NSW 2097. Alternatively phone (02) 979 5644 and quote your credit card details, or fax your order to (02) 979 6503. Price: $All.95 plus $A3 each for postage and packing. (NZ postage and packing $A6).