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SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.fluke.com.au Contents Vol.13, No.9; September 2000 FEATURES 4 How They’re Bringing You The Games As you sit back and enjoy the Olympics, think of the massive effort that’s gone into bringing them to you – by Ross Tester 26 Network Troubleshooting With Fluke’s NetTool It’s a snack to drive and it works like magic when it comes to tracing network problems – by Greg Swain 62 LA-CRO – A Must-Have For Students It’s a CRO, signal generator, frequency analyser, logic analyser, chart recorder and more, all in one compact package – by Peter Radcliffe Build A Swimming Pool Alarm – Page 12. PROJECTS TO BUILD 12 Build A Swimming Pool Alarm Don’t wait until summer; build this effective alarm now. It could save a child’s life – by John Clarke 32 An 8-Channel PC Relay Board It plugs into your PC’s parallel port and lets you control up to eight external devices – by Ross Tester 54 Fuel Mixture Display For Cars, Pt.1 Has digital readout and bargraph displays. A PIC microcontroller makes it a snack to build – by John Clarke Eight-Channel PC Relay Board – Page 32. 69 Protoboards: The Easy Way Into Electronics Use a protoboard to build a light chaser – by Leo Simpson 78 Cybug – The Solar Fly This simple robot is a great first kit to build. It’s Cybug, the solar fly, and he’s a real attention-getter – by Ross Tester SPECIAL COLUMNS 38 Serviceman’s Log The repair that didn’t make sense – by the TV Serviceman 84 Vintage Radio Fuel Mixture Display For Cars – Page 54. HMV’s Nippergram: a classic 1950s portable radiogram – by Rodney Champness DEPARTMENTS 2 20 31 42 53 Publisher’s Letter Mailbag Electronics Showcase Product Showcase Subscriptions Form 76 89 91 94 96 Circuit Notebook Ask Silicon Chip Notes & Errata Market Centre Advertising Index Cybug, The Solar Fly – Page 78. SEPTEMBER 2000  1 PUBLISHER’S LETTER www.siliconchip.com.au Publisher & Editor-in-Chief Leo Simpson, B.Bus., FAICD Production Manager Greg Swain, B.Sc.(Hons.) Technical Staff John Clarke, B.E.(Elec.) Peter Smith Ross Tester Rick Walters Reader Services Ann Jenkinson Advertising Enquiries Rick Winkler Phone (02) 9979 5644 Fax (02) 9979 6503 Mobile: 0414 34 6669 Regular Contributors Brendan Akhurst Louis Challis Rodney Champness Garry Cratt, VK2YBX Julian Edgar, Dip.T.(Sec.), B.Ed Mike Sheriff, B.Sc, VK2YFK Philip Watson, MIREE, VK2ZPW Bob Young SILICON CHIP is published 12 times a year by Silicon Chip Publications Pty Ltd. ACN 003 205 490. ABN 49 003 205 490 All material copyright ©. No part of this publication may be reproduced without the written consent of the publisher. Printing: Hannanprint, Dubbo, NSW. Distribution: Network Distribution Company. Subscription rates: $69.50 per year in Australia. For overseas rates, see the subscription page in this issue. Editorial & advertising offices: Unit 8, 101 Darley St, Mona Vale, NSW 2103. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 9979 5644. Fax (02) 9979 6503. E-mail: silchip<at>siliconchip.com.au ISSN 1030-2662 * Recommended and maximum price only. 2  Silicon Chip Electrical licence to build a kit is ridiculous A letter in the Mailbag pages of the June 2000 issue has generated more responses than any other issue ever raised in the history of SILICON CHIP. Entitled “Monkeys in charge of the kingdom” it raised the concern that it was illegal for people in Queensland to build mains-operated kits or even do repairs on mains-operated equipment unless licensed by the Electrical Li­censing board in that state. Since then we have had letters on the same subject in the July & August issues and quite a few since then, some of which are featured in this issue. As well, we have an official letter of response from the Queensland ELB which we have printed in full. Our reaction, on reading their letter, was that the ELB have their heads in the sand. Surely they cannot be “for real”. Safety is not really the issue. It is seen as an attempt by electricians to extend their sphere of influence into areas in which they previously had none. Sure, there are some electricians who are highly competent in some areas of electronics. But that does not mean that a restricted electrical licence should be required in order to service electronic equipment or assemble mains-operated electron­ic kits. The assembly of electronic kits and reading magazine arti­cles about electronic circuitry is the only way in which most people ever learn about electronics. In fact, do-it-yourself electronics has been the main activity which has generated tech­nical skills in this country, ever since radio broadcasting became possible, back in the 1920s. Do the various state ELBs really think they are doing the right thing by trying to restrict these activities to people who are licensed electricians? Do they realise the ramifications of this draconian approach? Would Australia be as technically inno­vative if this sort of regulation had been enforced in the past? Would we ever have developed a viable radio industry in the 1920s, 1930s, during World War II and so on, if licensed electri­cians were the only ones allowed to build or work on mains-oper­ated equipment? The answers to all these questions are perfectly obvious. If you have too much legislation and regulation you end up with a stultified society in which very little innovation occurs. Example - most of Europe. Keep it loose and you get an innovative society like America. Which path do we want to take? Clearly, the concept of only allowing suitably licensed people to assemble mains-operated electronic equipment is ridicu­lous. Next thing, they’ll want people to hold a licence to oper­ate their TV and microwave oven; after all, they are mains-oper­ated appliances and potentially lethal in the wrong circumstanc­ es, aren’t they? Having discussed this topic with the secretary and chairman of the Queensland ELB, I can assure you that they are perfectly reasonable people who do not have their heads in the sand. Although they have legislation to administer, they realise that they cannot regulate matters in this way. And most readers will cheer loudly on that score. But their letter resolves nothing. Let us hope, when they get around to reviewing the relevant legislation, that sanity will prevail. To that end, the ELB will be inviting submissions from interested parties in the near future. Ultimately, electricians should be the only ones to work on fixed mains wiring. We have no argument with that. But assembly and repairs on mains-operated appliances and electronic kits are none of their business. Leo Simpson                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 How they’re bringing yo The Ga a We probably don’t need to remind you about an event happening in Sydney (and other cities) this month. After almost a decade of bid preparation, winning the bid and planning, the Sydney 2000 Olympic Games have received, and will receive, more coverage than any event in history. Here’s how Australia’s telecommunications company, Telstra, along with international IT giant IBM have built the infrastructure those games are going to require. 4  Silicon Chip ou by Ross Tester Games a SEPTEMBER 2000  5 T his month, more than 10,000 athletes and 5000 officials from 200 countries will converge on Sydney to take part in 28 sports. About 15,000 accredited media personnel will provide TV, print and radio coverage for an estimated worldwide audience of more than 3.5 billion people. A further 8000 unaccred-ited media personnel will send stories about Australia to this massive global audience. The most comprehensive communications network in Games’ history has been set up for the Olympic Family, athletes, officials, broadcast and print media, other sponsors, security, head of state and all visitors to the Games and the Paralympic Games which follow. Working in closely with this is one of the largest, most complex information technology (IT) infrastructures ever built, to manage and distribute Games information to the world. The Millenium Network The Millennium Network is the communications network designed and developed by Telsta specifically for the Games. It combines the resour-ces and infrastructure of the existing Telstra network and several new Games-dedicated networks . Services include voice, data, video, mobile and trunk mobile radio. About 1100 technicians from around Australia will be involved in maintaining and operating the Millennium Network during the Sydney Olympic Games. In 1988 and 1992, Telstra worked with the Korean and Spanish telecommunications authorities on the Seoul and Barcelona Olympic Games respectively. More recently, they assisted with telecommunications at the 1996 Atlanta Olympic Games and the 1998 Nagano Winter Olympic Games, gaining invaluable experience for Sydney. The Millennium Network will service some 35 competition venues (12 at Sydney Olympic Park), three Olympic Villages (for athletes, media and technical officials), the Main Press Centre (MPC) and International Broadcast Centre (IBC), together with more than 100 non-competition venues (covering areas such as transport, ticketing and accreditation) and official training venues. The backbone of the Millennium Network is a series of fibre-optic rings linking all the venues with the International Broadcast Centre, key telephone exchanges and international gateways carrying data, telephony, audio and mobile services from the venues. Much of the supporting infrastructure that will serve the Games is already in use as part of the existing network. This includes optic fibre submarine cable connections to Asia, North America and Europe, satellite earth stations in Western Australia and Sydney, a national network of more than 1.2 million kilometres of optic fibre cable, digital switching and transmission facilities, and a digital mobile network that covers more than 94% of the Australian population. On top of this, several new dedicated networks around the main site, Sydney Olympic Park at Homebush Bay, have been specially built and installed. These include: • Transmission Network • Switched Networks • Mobile & Wireless Network • Broadcast Transmission Network • Video & Audio Networks • Cable TV Network • Data Network for IBM • World Network The Olympic Transmission Networks will deliver thousands of high quality circuits for broadcast video, audio, voice, high speed data, telephony, fax, ISDN and digital mobile phone base stations (GSM and CDMA). As well, there is a 60-channel Olympic cable television service plus other related communications services for Sydney and interstate venues, various road events, the International Broadcast Centre (IBC), Main Press Centre (MPC), Commercial TV and Telstra networks. The Millennium Network will provide up to 30,000 telephone and fax lines to the Olympic Villages, media centres and competition venues, in addition to capacity for 15,000 mobile communications services for the Olympic family. A close-up view of the huge screen in Telstra’s Global Operations Centre in Melbourne (seen also on the previous page). This centre controls and monitors all international traffic in and out of Australia and (including that from the Olympic Games control centre in Sydney. During September, this centre takes on an even more significant role than normal. 6  Silicon Chip Various types of media – voice, video and data – can be carried by the same fibre-optic network using the international SDH standard. Self-healing ring architecture protects against cable outages and node failures by providing duplicate, geographically diverse paths for each service. If a fibre is cut, the services affected are sent via an alternative path through the ring without interruption. Telephone services from all venues will rely on Centrex, a telephone system which delivers PABX-type services but unlike a PABX, all switching occurs at a local telephone exchange. Because the service is provided from a telephone exchange, it greatly improves reliability and peak traffic handling ability, as the much larger Sydney network is used to carry the Olympic traffic. The Centrex system also greatly reduces the need for cabling to venues, which would otherwise be redundant after the Games. A megametre of cable... Speaking of cabling, more than 1000km of building cabling and about 25,000 telecommunication outlets have been installed through all competition venues as well as selected non-competition venues such as the IBC, MPC and Olympic family hotels. The cable is PVC-free, to meet environmental standards. Copper cable is used for telephone, data, wideband services (at 2 Mbps), video cable, fax and audio commentary circuits (up to 15kHz). Fibre (much of it 155 Mbps) has also been run for IBM, the Sydney Olympics IT partner and major international sponsor. When the games begin, all systems will have had a thorough work-out at “test events” such as this basketball match held under Olympic conditions in Sydney. The mobile telephony network technology at Sydney Olympic Park for GSM mobile telephony includes micro cells and macro cells installed to cater to the large number of users expected in a comparatively small area. More than 60 indoor cells (customised systems) cover all venues requiring in-building telephony coverage. Some 140 outdoor micro cells cover outdoor areas within the common domain areas of Sydney Olympic Park and other venues. The micro cells function like standard mobile telephony cells but cater to a smaller coverage area. Six macro cells are used within the Sydney Olympic Park area, while one umbrella macro cell covers the entire park. The CDMA network for the Sydney Olympics operate from six macro cell stations and in-building micro cells, with each venue having at least one CDMA cell. A total of approximately 70 CDMA micro cells are used, with each cell fed with fibre back into the Telstra network. To maintain the aesthetic value of various buildings, the micro cells and antennas were camouflaged – disguising them in the same colour And a million mobile phones The mobile and wireless network has been designed to not only meet the requirements of Games organisers but to deliver additional capacity to meet the massive demand for mobile services expected from spectators. Both GSM and CDMA networks are involved. In Sydney Olympic park, Darling Harbour and other Games venues, the existing networks’ capacity has been expanded to provide the densest mobile coverage ever seen (or heard). Capacity has been planned to cope with the mobile phone needs of up to 500,000 spectators at Sydney Olympic Park and an additional 500,000 people in the Sydney area. About 1100 Telstra technicians from around Australia will be involved in maintaining and operating the Millennium Network during the Sydney Olympic Games. In some instances, particularly at major venues and broadcast and media facilities, staff will rostered to provide 24 hour service. SEPTEMBER 2000  7 as the building and installing them in unobtrusive locations within buildings. “Leaky Coax” technology “Leaky Coax” – radiating coaxial cable – is a signal-boosting technique commonly used in locations where RF signals are too weak to provide reliable communications. It uses pre-cut holes that emit a controlled amount of RF energy. This leakage along the cable’s length provides continuous coverage along the chosen route. Leaky coax cable will be used as the antenna system in confined areas such as train tunnels and railway platforms so mobile phones may be used on trains and on the platform at Olympic Park railway station. Digital trunk radio The Olympic Radio Network, a digital trunk radio system, will be used during the Games for a range of operations, transport, emergency services and security functions. The system comprises 12 base stations, employing 224 transmitters across the Sydney metropolitan area. Three of the base stations are in the vicinity of Sydney Olympic Park and two of these provide in-building coverage for Stadium Australia and the Sydney International Aquatic Centre. Every site has one control channel to manage traffic across the network, plus talk channels, which range from seven for small sites up to 27 for the largest site. The digital system supports as many as 9,000 radio handsets for SOCOG, organised into as many as 100 user groups, or ‘Talk Groups’ of customers each with their own handset. The Olympic Security Command Centre will use another 3000 handsets. Video and audio The Telstra Video and Audio (VandA) network provides high quality video and associated audio services. The network is based mainly on pointto-point fibre, with some venues using SDH. VandA will also be available to other locations such as beauty spots and road events and any other location connected to the existing fibre network. The video and audio interface being offered to the broadcasters are standard broadcast formats: PAL with associated audio or SDI 270 Mb with embedded audio. Games cable TV A special purpose 60-channel analog cable TV (CATV) point-tomulti-point video service has been installed for the Olympics. This network enables the Olympic family to follow Games progress and is required to provide media and broadcasters with monitoring facilities at all events in all venues. It also allows athletes to follow progress of events from their Village. The cable TV content will be sourced from Sydney Olympic Broadcasting Organisation (SOBO) at the IBC and distributed via the network to all competition and non-competition venues in Sydney, including the Olympic villages. The two forward fibre transmitters working at 1550 nanometres will enable service within a 40km radius of the IBC, including the furthest Sydney venue, Penrith Lakes. Information technology The IBM Global Services Olympic technology team has developed three core information systems: the Games Management Systems; the Results System; and INFO, an intranet-based information resource for the 260,000 members of the Olympic Family. Olympics Communications and Information Technology In Brief:  The Millenium Network, the communications system created by Telstra especially for the Games, has been in planning and development for nine years;  It services more than 35 competition venues, three Olympic Villages, the International Broadcast Centre, the Main Press Centre, a Technology Command Centre and dozens of training venues;  It services more than 50 non-competition venues;  It has more than 4,800 kilometres of optical fibre connecting the Olympic venues and the International Broadcast Centre – more than five times the distance between Sydney and Melbourne;  It has 280 video links from sporting venues to the International Broadcasting Centre and 3,200 audio links – 90% for use by broadcasters, the remainder for organisers and emergency services;      It has 250 data links for timing and scorekeeping; It has 60 private cable TV channels to provide live action to the IBC and the Olympic venues and villages; It links into Telstra’s national network of 1.2 million kilometres of optic fibre; It provides international access via 11 satellites and submarine cables. And it will offer facilities for HDTV transmission from Australia.  Three Information Technology systems have been developed by IBM – the Games Management System mainly used by SOCOG to run the Games, the Results System(including commentator information) and the INFO general information resource which goes out to 2000 workstations and Olympic information kiosks.  Want more information? Visit the games website, www.olympics.com or Telstra's website, www.telstra.com 8  Silicon Chip In addition, IBM is working jointly with SOCOG, developing and managing the Official Sydney 2000 Olympic Games Web site, www.olympics.com Games management systems The Games Management Systems is a set of applications which SOCOG uses to run the Games. Applications include accreditation, medical, arrivals and departures and incident tracking. In addition, SOCOG is providing a set of additional applications including Olympic entries, qualification, accommodations, staffing, ticketing and transportation. Games result system The Games Results System is made up of two major components, the Venue Results applications and the Central Results System. The Venue Results applications collect competition data including timing, scoring and statistical information from each event, process the results based on international sport federation rules and feed them to scoreboards and a variety of other output devices in the Olympic Games venues. Results are fed to the Commentator Information System (CIS), used by more than 1,000 broadcast media personnel at the Games and to the TV graphics for display on TV screens around the world. The Central Results System is a massive data warehouse managed by a DB2 database, hosted by an S/390 Parallel Sysplex server and stored in RAMAC Virtual Array storage devices. INFO is the “electronic encyclopedia of the Games” and distributes comprehensive information about virtually every aspect of the Olympic Games — past and present — to more than 2,000 workstations and kiosks to athletes, officials, the media and the general public. The Central Results System is at the heart of the Olympic Games, accessible 24 hours a day. The system receives competition information from the Venue Results applications and distributes it to 15,000 media personnel via more than 700 printers. At the competition venues, printed results are also distributed to international sport federation officials, athletes, coaches and media. The Central Results System also transmits the competition results to the World News Press Agencies (WNPA) and feeds this information to INFO for viewing by the Olympic Family and to the Official Games Web site for the public. An IBM S/390 computer is at the central site with IBM Netfinity servers located in the venues via both local area networks (LAN) and a wide area network (WAN). In all, approximately 9,000 IBM Personal Computers and ThinkPads are or will be connected to this Olympic Games network to provide access to critical data within the venues and to communicate with the Central Results System. CIS: the broadcaster’s information resource The Commentator Information System (CIS) is available for 10 Olympic Readers outside the Sydney area may not realise how large it is – and the distances involved. This map shows the venue distances from Sydney Olympic Park at Homebush Bay (No. 1). The Olympic Rowing Course at Penrith Lakes (No. 13) is almost 40km away. Even so, all Olympic venues are no more than a 45 minute drive from Sydney Olympic park or Newington, the new suburb alongside which houses all athletes and team officials. All venues on this map are networked with fibre-optic cable. SEPTEMBER 2000  9 sports. CIS provides international broadcasters with real-time competition information directly from the venue databases, enabling them to bring their audiences timely coverage right from the field of play. Broadcasters access CIS through touch-screen workstations located in commentator booths in the Games venues. At any time commentators can call up results, statistics, medals data and current Olympic Games information to enhance their broadcasts and event coverage. CIS workstations receive unofficial competition results through a dedicated local area network (LAN) in each venue the moment the information becomes available. Once competition results are made official by the sport’s governing body, CIS is immediately updated to reflect the final results. INFO System: streamlining information access INFO is an intranet-based system that is the primary resource for sharing information among the Olympic Family. This “electronic encyclopedia of the Games” distributes comprehensive information about virtually every aspect of the Olympic Games — past and present — to more than 2,000 workstations and kiosks located throughout the Olympic venues. INFO users can access the following information categories: results and statistics; biographies and profiles; historical results; medal information; records; schedules; news; transport; weather and facts & figures. In addition, accredited Olympic Family members including media, athletes, coaches, volunteers, broadcasters, international sport federation members and International Olympic Committee (IOC) and Sydney Organising Committee (SOCOG) staff are provided with an email address within INFO, allowing them to send mail and post messages for one another via electronic bulletin boards. INFO workstations located in media centres and Games venues are IBM PCs running a Netscape Communicator browser on a Windows NT platform. The Olympic Games website: www.olympics.com Together SOCOG and IBM are creat10  Silicon Chip ing the Official Sydney 2000 Olympic Games Web site. One of the largest event Web sites in the world, it makes the Sydney Games more accessible to sports fans worldwide. Containing about 30,000 pages of information, this site is expected to receive in excess of two billion hits during 2000. Anyone with a Web browser and Internet access can browse the official Web site for a wide range of information about Sydney and the Games, including: sports and venues, news, arts festivals, tickets and merchandise. The site has been updated regularly as preparations for the Games are finalised. During the Games, additional information and services will be available, including real-time results, photos, athlete biographies and interactive features. And Olympic information on to the world… Sydney Olympic Park venues are redundantly linked to IBM’s two data network hub centres at Homebush via a dedicated fibre network. These break out into IBM computer systems in the hubs. The Homebush dedicated fibre network will deliver 155Mb connectivity per link. There is a dedicated transmission network linking the IBC, International gateway exchanges in Sydney at Oxford Falls and Paddington and a national transmission hub exchange, also in Sydney. Video traffic will leave Australia via earth stations Sydney and Perth, Western Australia, under the overall control of the Global Operations Centre in Melbourne. It will use a combination of SDH transmission technology with self-healing ring structures and some direct optic fibre from venues on diverse paths. Most broadcasters are expected to use digital compressed video due to its cost effectiveness and its ability to put out more than one channel simultaneously. Four digital video channels can be accommodated per transponder bandwidth compared to one using analog technology. The compression technology is based on MPEG-2. To provide a remote area and multipoint distribution network, the national terrestrial network is complemented by a satellite network incorporating PanAmSat’s PAS-2 Australia/New Zealand beam. Internationally, Telstra has transmit and receive access to a wide range of INTELSAT satellites in the Pacific area, Asia Pacific and Indian Ocean regions, as well as access to PanAmSat and AsiaSat systems. These satellites are accessed via satellite earth stations in Sydney (Pacific area and Asia Pacific regions) and SC Perth (all three regions). Acknowledgement: Information and photographs courtesy Olympic media departments of Telstra and IBM. Games images to the world’s TV audience will leave Australia via earth stations in Sydney and Perth in Western Australia. SEPTEMBER 2000  11 Drowning is one of the primary causes of accidental death in children under five. SILICON CHIP would love to see that statistic eliminated – and this simple, effective pool alarm could assist in that aim. Don’t wait until summer: build it NOW! Features  Compact, battery operated  Free-floating unit  Loud siren sounds upon    sudden pool water mo vement  Reduced sensitivity to win d movements and side-of-p ool collisions  Splashproof and rain proof  On/Off switch for pool use  Test switch lowers siren vol ume  50 second alarm Swimming Pool Alarm by JOHN CLARKE 12  Silicon Chip W hile properly designed and maintained pool fences are the primary line of defence in preventing young children falling into a pool, they are not enough. Indeed, we speak from first-hand, recent experience: Georgia, the 18-month-old “model” used in our photographs, was found leaning over the edge of the pool (after that same ball) shortly after the photographs were taken. The reason – the gate had not latched properly. We shudder to think what might have been if we weren’t close by. Needless to say, the gate latch has now been fixed … and we now have a SILICON CHIP pool alarm floating in the water. The problem is, children are very resourceful when it comes to getting to a pool: the smallest gap in the fence; a box or chair left where it can be climbed on (or dragged to the fence); even a dog digging a tiny hole under the fence (if a dog can squeeze through it, a small child can often do so too…) So it is unwise to be complacent about pool safety, even if you think your pool fence is impenetrable. Some people install a closed-circuit TV system to monitor their pool area, with the screen in, say, the kitchen. That’s pretty good to keep watch over the kids while they’re in the pool and mum, for example, is inside. But what happens when she’s not in the kitchen? And even the best TV monitoring system is useless when you’re away and the neighbour’s toddler finds his or her way into your backyard… A much better form of protection is to use a device which can detect someone actually falling into the pool – and then screams its head off. Of course, it would be better to detect them before they fall in but that’s It’s like an insurance policy: you never know when you need it but you’ll always be grateful that you had it if it’s ever really needed! getting even more difficult! One way to detect someone falling into the pool is to sense any small change in the water level and set off an alarm if the change in level matches certain parameters – for example, changes caused by wind or filter Specifications ...... 330uA at 6V Battery current drain....... .... >6 months Expected battery life............ ally 50 seconds Alarm duration..........typic typically .01g Movement sensitivity.......... action need to be rejected). The SILICON CHIP Swimming Pool Alarm is based on this principle. It is fully self-contained and battery operated. There is a small plastic box which is simply left to float on top of the pool surface (you could loosely tether it if necessary). Inside is a sensor which detects small, though rapid, changes in the pool water level as would happen when someone falls in. On detecting this change, a siren sounds. It’s designed to be left on all the time, except of course when the pool is being used. A waterproof on/ off switch is provided to allow it to be removed from the pool without sounding, and there is another switch which tests the alarm (at reduced volume) to periodically check the battery. Detection Detecting a small child’s body entering the pool is rather difficult. The monitoring must attempt to exclude normal pool movements caused by wind or filter operation but still detect changes in water level. Even this is not foolproof: if the Fig.1: the block diagram of the SILICON CHIP Swimming Pool Alarm. The weighted piezo sensor detects water disturbance in the pool. SEPTEMBER 2000  13 Fig.1: the low frequency signal from the piezo sensor is amplified to trigger the siren driver. person climbs slowly down the ladder the rate of change in water level might be virtually nonexistent. By contrast, anyone actually falling into the pool will usually make quite a splash with lots of movement of the pool surface. Even a child overbalancing while leaning over the pool edge to retrieve a toy or ball (by far the most common scenario) will make large ripples on the pool surface. Water level change detection is a compromise between sufficient sensitivity for the purpose intended while rejecting normal pool movement due to wind, etc. As such, it may produce false alarm signals on a windy day. What we are saying is that this method of sensing water level change can never be 100% reliable but it is about as reliable as can be achieved (within reason). No pool alarm can give you absolute assurance – it is very much your second line of defence. Always ensure the pool fence and gates are in perfect 14  Silicon Chip order and remain vigilant while ever kiddies are around. Block diagram The block diagram of the Swimming Pool Alarm is shown on Fig.1. The sensor itself consists of a piezo element which supports a weight. The piezo element is attached to a floating box which floats on the swimming pool surface. Any upwards-movement of water will cause the floating box to rise, pushing against the piezo which doesn’t move as quickly due to the inertia of the attached weight. When this occurs, the piezo element generates a small voltage output. Note that a downward movement of the box will not usually cause decompression of the element. This is because the floating box drops with gravity at the same rate as the mass. The signal from the piezo detector is amplified by IC1a and filtered so that only frequencies below about 2Hz pass through. The amplifier has a gain of 33 for frequencies below 2Hz. As the mass on the piezo element also damps out any fast movement (again due to inertia), it reduces the high frequency response of the piezo element. Thus the output from the filter only changes for slower movements. The signal is squared up by the following Schmitt trigger (IC1b) and has an adjustable threshold to allow setting the sensitivity to pool movement. The Schmitt trigger output is a low frequency square wave which changes with the piezo detector output. The signal drives a charge pump which requires at least two pulses from the Schmitt trigger before the output from the charge pump is low enough to trigger the following timer. This requirement before triggering the timer reduces the likelihood of false alarms. The timer produces a high signal for about 50 seconds which drives the siren driver (Q1) and siren. The siren should be sufficiently loud to attract attention. The circuit is housed in a sealed box to prevent water getting in. However, the siren must be exposed to the outside air so that it can be heard. It also needs to be made as loud as possible to attract attention. This is done by feeding the siren into a tuned port, covered to make it splashproof. Actual dimensions of the port and cover are fairly critical to maximise the sound output level. Simply placing an untuned cover over the siren outlet would severely muffle the volume. Fortunately, we found a couple of easily-obtainable items made a near-perfect port: the flange or front section from a standard bayonet-cap light fitting (the bit that screws on to the actual lampholder which holds a lampshade or diffuser in place) and half a table-tennis (or ping-pong) ball! Circuit Use this component overlay with the photograph below as a reference while building the Pool Alarm and you shouldn’t go wrong. The two 25mm M3 screws don’t actually hold anything – they're there (with the four small “L”shaped brackets not shown in the photo) to stop the battery holders slopping around in the case. Fig.2 shows the circuit for the Swimming Pool Alarm. Signal from the piezo transducer is connected to the low pass filter, comprising IC1a and the associated resistors and capacitors. The 100kΩ resistors and 1µF capacitors set the low pass filter at 2.3Hz, while the 3.3MΩ feedback resistor and .015µF capacitor set the gain at 33 times at or below the 2.3Hz rolloff frequency. IC1a is biased at 1/2 supply (+3V) at pin 3 by the 1MΩ voltage divider resistors connected across the supply. This half supply is decoupled with a 100µF capacitor. The output of IC1a is also at 1/2 supply and this drives a 2.2kΩ resistor decoupled with a 470µF capacitor. The voltage across the 470µF capacitor is therefore at 3V (1/2 supply) and the resistor and capacitor form a low pass filter to reject signals above 0.15Hz. Hysteresis for the Schmitt trigger (IC1b) is set by the ratio of resistance between the 3V supply and pin 5 and the resistance between pins 5 & 7. Thus the hysteresis can be varied from about 13mV when VR1 is wound with its wiper closest to the 2.2kΩ resistor and around 300mV when VR1’s wiper is closest to the 1MΩ resistor. The output of the Schmitt trigger is used to drive a “charge pump” consisting of diodes D1 & D2 and capacitors C1 & C2. These produce a voltage negative with respect to the +6V line across capacitor C2 whenever IC1b's output is toggling (ie, the circuit is sensing water disturbance). SEPTEMBER 2000  15 The voltage across C2 is fed to pin 2, the trigger input of timer IC2. IC2 is triggered when its pin 2 goes below one third of the supply voltage, or 2V. When triggered, the 47µF capacitor begins charging via the 1MΩ resistor and the pin 3 output goes high and drives transistor Q1’s base via the 2.2kΩ resistor. This transistor drives the siren. The siren can be driven directly via the 6V supply or via the 10kΩ resistor connecting to the 6V supply for a reduced output level (for testing). This is selected using switch S2. The output of IC2 (pin 3 ) stays high until the 47µF capacitor at pin 6 reaches two thirds of the supply voltage. The pin 3 output then goes low and the capacitor is discharged via the pin 7 output and 10kΩ resistor. The time duration for the alarm is around 50 seconds. When power is first switched on, the reset input of IC2, pin 4, is held low via the 10µF capacitor to prevent the timer from being triggered by IC1b. After about a second the reset pin voltage reaches about 1V due to the 10µF capacitor being charged via the 560kΩ resistor and then the timer can be triggered. Construction The Swimming Pool Alarm is constructed using a PC board coded 03109001 and measuring 89 x 80mm. This is housed in a sealed plastic enclosure measuring 115 x 90 x 55mm. It is important to use this case, not the plastic project boxes we normally use, as this one has an integral gasket in the lid ensuring it is waterproof. A front panel label measuring 108 x 85mm attaches to the lid of the case. We used a flange cover from a bayonet light socket to cover the piezo siren outlet and made a splashproof hood for it by cutting a table tennis ball in half. The front panel switches were also waterproofed with rubber hoods. Begin construction by checking the PC board for shorts or breaks in the tracks. Also check the hole sizes for fit, especially for the PC stakes, the 3mm screw holes required for the piezo transducer and AA cell holder locating screws. The four corner holes need to be 3mm in diameter. Insert and solder in the resistors and diodes D1 and D2. Use the accompanying resistor colour code table as 16  Silicon Chip We used the flange from a standard 240V light fitting (at left in photo above) to form the “tuned port” cover over the piezo buzzer. This was capped with half a ping-pong ball. The diagram at right shows how the various parts are assembled. a guide to selecting the correct values for each position. If in doubt use your multimeter to verify values. Note that the 560kΩ resistor is mounted on its end as shown. Ensure that D1 and D2 are inserted the right way around. When mounting IC1 and IC2 take Parts List – Swimming Pool Alarm 1 PC board coded 03109001, 89 x 80mm 1 sealed ABS enclosure, 115 x 90 x 55mm (Jaycar HB-6126 or DSE H-2863 or equiv.) 1 front panel label 111 x 87mm 2 2 x AA cell holders 4 AA cells 1 dual sound piezo buzzer (Jaycar AB-3456 or equiv.) 1 piezo audio transducer 30mm diameter 2 SPDT toggle switches (S1,S2) 2 waterproof boots or hoods for toggle switches 1 brass or lead cylinder 15mm OD x 19mm* 1 flange cover from a mains bayonet light socket or line socket (tapered from 36mm to 32mm over 35mm length. 1 38mm diameter table tennis ball 2 40mm lengths of 1.25mm diameter cold drawn brass wire 4 right angle brackets 7 x 9 x 10mm wide 4 M3 x 6mm screws 2 M3 x 10mm screws 2 M3 x 25mm screws 4 M3 nuts 11 PC stakes 1 200mm length of red hookup wire 1 200mm length of black hookup wire Semiconductors 1 TL062 dual low power op amp (IC1) 1 7555, LMC555CN CMOS 555 timer (IC2) 1 BC338 NPN transistor (Q1) 2 1N914, 1N4148 switching diodes (D1,D2) Capacitors 2 470µF 16VW PC electrolytic 1 100µF 16VW PC electrolytic 1 47µF RBLL electrolytic 1 10µF 16VW PC electrolytic 3 1µF MKT polyester 1 0.56µF MKT polyester (used while adjusting sensitivity) 1 0.22µF MKT polyester 2 0.1µF MKT polyester 1 .015µF MKT polyester Resistors (0.25W, 1%) 2 10MΩ 1 3.3MΩ 5 1MΩ 1 560kΩ 3 100kΩ 2 10kΩ 3 2.2kΩ 1 50kΩ (503) horizontal trim pot (VR1) Miscellaneous Solder, neutral cure Silicone sealant (roof & gutter type), “body” for setting sensitivty etc.   *See text for alternatives These two photos give a good idea of how the whole lot goes together, especially the “tricky bits” – securing the weight to the piezo trans-ducer and splash-proofing the piezo buzzer with a flange from a light fitting and half a ping-pong ball. care with their orientation. Likewise, the electrolytic capacitors (the MKT types can be mounted either way around). The accompanying capacitor code table will help you in selecting the value for each position. Transistor Q1 and the PC stakes can be inserted and soldered in position now. Finally, trimpot VR1 can be installed. Piezo and weight Remove the back from the piezo transducer by prising the two halves apart (the back is not used and can be discarded). Attach the transducer in place upside down on the PC board using 10mm M3 screws and nuts. For the weight attached to the transducer, we used a piece of brass water tap plunger (the part that pushes the valve down when you turn the tap off), cut to 19mm long to clear the back of the piezo buzzer when the case is assembled. Alternatively, you could use a 19mm long piece of 13-14mm diameter brass rod, or you could fashion your own weight using a plumbers’ fitting such as a 12.5mm (1/2") brass pipe cap (also known as a stop end), cut to 19mm long and filling it with lead or even solder. This weight is glued to the piezo element on the transducer using a smear of silicone sealant between Resistor Colour Codes        No. Value 4-Band Code (1%) 2 10MΩ brown black blue brown   1 3.3MΩ orange orange green brown   5 1MΩ brown black green brown   1 560kΩ green blue yellow brown   3 100kΩ brown black yellow brown   2 10kΩ brown black orange brown   3 2.2kΩ red red red brown      5-Band Code (1%) brown black black green brown orange orange black yellow brown brown black black yellow brown green blue black orange brown brown black black orange brown brown black black red brown red red black brown brown the mating faces. Allow the sealant to cure. Also, while you have the silicone sealant out, put a small dab in the holes in the base of the case. This will trap air inside the holes and provide extra buoyancy. The lid and cover Cut a 25mm diameter hole in the centre of the case lid, either with a 25mm hole-saw, or by first drilling a series of small holes around the required perimeter and removing this piece then filing to shape. The piezo siren should be a tight fit in the hole. Next drill the holes for the two switches using the front panel artwork as a guide to their position. We made our cover for the piezo siren from a flange from a standard Capacitor Codes Value 1µF 0.56µF 0.22µF 0.1µF .015µF IEC code 105 564 224 104 153 EIA code 1u 560n 220n 100n 15n SEPTEMBER 2000  17 (bayonet cap) light fitting. They’re all much the same size. The flange is placed with the larger diameter end on the lid. File a couple of small notches in this larger diameter end so that water can flow out through these if some does enter. Test that the notches are large enough for water to flow out by placing the end on a flat bench (eg, bathroom sink) and pouring some water in. The water should flow out leaving only a couple of drops inside. The smaller diameter end of the bayonet flange requires brass wire crosshairs to be placed symmetrically across the opening so that the cut in half table-tennis ball can be held in place over the opening. We secured the crosshairs in place by melting the wires into the plastic flange using a soldering iron. The table tennis ball is cut in half using a fine toothed hacksaw and smoothed by rubbing the cut edge on a sheet of fine glass-paper on a flat surface. The half ball is secured centrally over the wire crosshairs and secured at these four points with silicone sealant. Attach the bayonet flange to the lid with a smear of silicone sealant taking care not to fill the water outlet notches cut previously. Four small L-shaped brackets are required to hold the two AA cell holders in place. We made ours from some bits of chassis-mounting capacitor brackets but any small pieces of metal would be fine. Exact size isn’t critical – ours were about 7mm wide and each leg was about 9-10mm long. One of the legs on each bracket needs to be drilled to accept the M3 screws. Further support for the AA cell holders is provided by the 25mm M3 screws mounted on the PC board. When the silicone sealant has dried, you can attach the front panel label and secure the switches in place along with their rubber boot covers. Wire up as shown and insert the PC board in place remembering to also attach the right-angle battery holder brackets under the corner mounting screws. Insert the cells and switch on power. Set S2 to the test alarm position. Check that there is 6V between pins 4 and 8 of IC1 and between pins 1 and 8 of IC2. Pin 1 of IC1a should be at around 3V after about 60 seconds from power being switched on. Jerk 18  Silicon Chip Full-sized artwork for the Pool Alarm front panel and PC board. A photocopy of the front panel makes a handy drilling template for the case lid. the box upward and check that the siren sounds for about 50 seconds. The “body” test Testing in the swimming pool needs to be done with the lid secured on with its neoprene gasket in place. That means you’ll need to remove the lid each time you need to adjust the sensitivity pot, VR1 but otherwise you risk filling the alarm with water! VR1 should be adjusted so that the alarm will sound when a person enters the pool but not so sensitive that it is triggered with normal pool water movements. Adjustment of VR1 may be easier on your ears if you temporarily replace the 47µF capacitor on pin 6 of IC2 with a 0.56µF capacitor. This will reduce the alarm time to less than one second. First, though, you'll need to find a small volunteer “victim” (the smaller the better) – but please, make sure they can swim! Get them to jump in, fall in and even “ease” themselves into the pool, setting the sensitivity pot (VR1) as low as you can with the alarm triggering reliably every time they go in. To check that it will work with a toddler, we don’t suggest throwing one in(!) but perhaps a few bricks wrapped in towels, weighing say 7-10kg, would be a reasonable approximation. SC DON’T UTER COMP MISS OMNIBUS THE ’BUS! www.siliconchip.com.au SILICON CHIP’S 132 Pages $ 95 * 9 ISBN 0 95852291 X 9780958522910 09 9 780958 522910 IN LINCLUDES FEA U TUR X E A collection of computer features from the pages of SILICON CHIP magazine Hints o Tips o Upgrades o Fixes Covers DOS, Windows 3.1, 95, 98, NT o RT Do you feel a little “left behind” by the latest advances and developments in computer hardware and software? Don’t miss the bus: get the ’bus! THIS IS IT: The computer reference you’ve been asking for! SILICON CHIP's Computer Omnibus is a valuable compendium of the most-requested computer hardware and software features from recent issues of SILICON CHIP magazine - all in one handy volume. Here's just a sample of the contents: Troubleshooting your PC: what to do when things go wrong NO Choosing, installing and taming computer networks AVA W Upgrading and overclocking CPUs DIRE ILABLE C Hard disk drive upgrades, tune-ups and tips SILIC T FROM Windows 3.1, 95, 98 and NT tips and tricks ON just $ CHIP The Y2K Bug - and how to swat it 125O* INC All about Linux GST & P& P And much more!!! ORDER NOW: Use the handy order form in this issue or call (02) 9979 5644, 9-5 Mon-Fri with your credit card details. * Price includes GST 09 MAILBAG Cars are still very inefficient With some misgivings, I read your glowing editorial enti­ tled, “42V Electrical Systems In Cars”, about the radical changes in automotive engineering, in the July 2000 issue. I would like to quote some sobering facts from an authoritative Victorian car magazine. In the average city driving cycle, only 13% of the energy your car generates actually ends up propelling it forward! (The magazine is talking about the current generation of cars). The highway driving cycle is somewhat less brutal on your car’s energy output, but still only 20% gets transferred to forward motion. After well over a hundred years of automotive engineering, I think we can only classify the car as a very backward piece of design. W. Beyer, Longford, Vic. Electrical licensing is a joke I am writing in regard to the letter entitled “Monkeys in charge of the kingdom” in the Mailbag pages of the July 2000 issue. I would like to support the contents of this article and confirm that a similar situation exists in South Australia. The electronics industry has largely been considered as a group of hobbyists content to quietly sit in a back room and do their thing. It’s about time we had this image changed. No other group has had to face the rapid changes in techno­logical advances, diversification and growth, from valves, tran­sistors, integrated circuits to large scale integrated circuits, from point to point wiring to simple printed circuit boards on to multilayer printed circuit boards, from simple single valve radios to big powerful computing systems. The list goes on and on. There is no facet of life that is not affected or controlled by electronics. This has happened in ONE human lifetime. What more needs to be said 20  Silicon Chip about the role of electronics in the every­day safety of people? The current electrical licensing system is a joke and needs to be shown up for what it really is. I have been an electronics technician for over forty years working on aircraft, scientific and research equipment, industrial control systems and automotive equipment. I have attended college/TAFE courses in advanced electronics, small computer maintenance, refrigeration, industri­ al programmable logic controllers and a year’s part-time course on understanding AS3000 and AS3008. I also developed an in depth understanding and application of power controllers for both DC motor and AC motor inverters up to 150 HP. To add insult to injury, I have just received a bill for $206.00 as a fee to renew my restricted “B” class licence for one year. This allows me to work on electronic equipment hard-wired to the mains supply. BIG DEAL. Previously this licence was no fee (correct value). I have tried to get this licence upgraded to something useful, but no way unless I can do an apprenticeship as an electrician. I hope this letter is useful in supporting your other correspondent. Name supplied and withheld at writer’s request. Electrical licensing a catch-22 situation I totally concur with the letter in the July issue refer­ring to the Electrical Licensing Boards as “monkeys in charge of the kingdom”. I believe they are a barrier to people with initiative. In Western Australia these people do everything they can to prevent anyone obtaining an electrical licence. Unfortunately, the real world is that almost every work practice involves elec­tricity and hence electrical wiring. Having an electrical licence is now a necessity. The WA Licensing Board won’t even consider you if you don’t al- ready have a job that requires you to do electrical wiring. This is a catch-22. If you can argue your case, after much dis­cussion (delays) on their part, you may be allowed to attend classes for a restricted licence that costs a fortune to learn basic electricity that you already know. Further to this, you then need a qualified person to supervise you for so many months afterwards depending on the type of licence. In fact, the only people I am aware of that are currently doing their electrical licences are people who have relatives that are already qualified electricians. It is a rubber stamp of approval for them regardless of their abilities. They then obtain their electrical A-class licences which allows them to work on just about everything. Why aren’t these Electrical Boards forced to do some genu­ine work? Why don’t they organise realistic training programs such that a licence fits the skills acquired? Let’s get some accountability into these power brokers. Electricians refer to anyone without a licence as “cowboys” but you only have to see their workmanship to see who the real cowboys are. Ask an electrician how a Wattmeter works; it stumps them every time. I would ask you to withhold my name and address as I too must “play the game” and go cap in hand to the Board in the hope of having a crumb of a restricted licence thrown at me. Letter was in poor taste I am responding to the letter in your July 2000 Mailbag page, headed “Monkeys in charge of the kingdom”. As an electri­ cian by trade and a subscriber of SILICON CHIP for many years, I was not only offended but found the article to be of very poor taste (even though the Editor’s comments tried to water down the text). I agree with the writer’s complaint concerning his occupa­tion and the Queensland Electrical Licensing Board regulations but I suggest he stays focused on that issue. Whilst I can only aspire to the intellect of a “TAFE quali­ f ied technical officer”, I have always enjoyed your magazine, and have successfully constructed many of your projects. I trust the contents of the next issue can be enjoyed by all occupations. A. Doust, Erskine, WA. Qualified electronics people make mistakes too I feel I must reply to the “Monkeys in charge of the king­ dom” letter in the July 2000 issue of SILICON CHIP. Your corre­ spondent in one point said he had to rewire devices. Well, I for one have had to replace, repair or whatever articles left in a poor/dangerous state by so-called technical offices (with re­ stricted licences). Maybe more restrictions are required. I am employed in industrial repair and maintenance involv­ing such varied items as PLCs, process control, high voltage (11kV), switching, motor control (VF drives and soft starters) up to 400kW, as well as cable dragging mentioned by your corres­pond­ent, and I know of a large number of electricians who are in the same field, which involves a large amount of working on electron­ic equipment. I have also been involved in computer work, both hardware and software-based (includ-ing TCP/IP networks, RS232/485 comms circuits, etc.) I take personal offence to your correspondent’s comments (and also your comments) re electronic equipment building, having built various projects myself over the years. I feel a lot of other electrical fitters would also take offence to the comments. Also, I note your correspondent mentions the “Electrical Workers Board” in Queensland. It is now known as the Electrical Licensing Board. During the last 12 months (1st July 1999 - 30th June 2000) ALL electrical licences (both electrical fitter/joint­ er/linesperson and restricted licences) have had to be renewed, so maybe your correspondent is now working unlicensed. So maybe your correspondent just has sour grapes about not being able to do as he pleases. Would you employ a butcher (no offence meant) to fix your house wiring? Please withhold my name and address (as your correspondent has) as I don’t want hate mail, etc. The official response from the Queensland ELB The Electrical Licensing Board (ELB) recently received a copy of an extract from the July 2000 edition of SILICON CHIP. A latter article in the Mailbag section entitled “Monkeys in charge of the kingdom” drew the attention of the ELB who considered it appropriate that a response be forwarded to you. The writer of the letter raised concerns that it is not legal to build kits in Queensland without an electrical licence. We consider an explanation is warranted to explain the issues involved and particularly the Board’s concern for electrical safety. Restricted electrical licences related to plug-in equipment are available to suitably qualified and experienced persons and allow, on mains-operated equipment, the replacement or repair of flexible leads, fault finding and the replacement of electrical component parts. In Queensland many of these restricted electri­cal licences are issued to persons involved in the electronics field. The ELB encourages people involved in the electronics field to gain knowledge of the basic electrical safety principles and has been successful in having these principles covered in elec­ t rical traineeships and education courses thereby ensuring ex­perience to qualify for a restricted licence in a person’s field of work. Work on equipment operating at extra low voltage, not more than 32V AC or 115V DC, is not subject to licensing. In addition, an electrical licence is not required at an industrial workplace for manufacturing, assembling or repairing electrical articles if the principal manufacturing process carried on at the workplace is the making, assembling, altering, repairing or adapting of electrical articles. Accordingly, not all work on the kits re­ferred to is subject to electrical licensing. We are sure that service persons would be aware of the potential electrical safety concerns if appropriate standards and testing procedures are not followed. For example, there are cases where inappropriate modifications to television receivers have caused electric shock via the aerial connections. There are also many other cases where people don’t recog­nise the hazards of their activities and have carried out work that has serious electrical safety concerns. While it is recognised that some electricians do not have the necessary skills to carry out electronics work, a fundamental requirement of the licensing system is the responsibility for the licence holder to only perform work they are competent to under­take. To enhance competence in the licensing system, every elec­trical worker is also required to furnish proof of skills main­tenance in key electrical safety areas at licence renewal. The Board has been advised that a review of Queensland’s electrical safety legislation is planned in the near future. This will involve full stakeholder consultation and no doubt this issue will receive attention as part of the review. I trust your readers now more fully understand the concerns Board members have for electrical safety and assist in the promo­tion of electrical safety throughout the community. Eugene Ladyko, Secretary, Electrical Licensing Board, Brisbane, Qld. SEPTEMBER 2000  21 SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.dse.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.dse.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.dse.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.dse.com.au Network troubleshooting with Fluke’s NetTool Small networks involving just a few PCs are easy to troubleshoot but it’s a different story with larger networks. Fluke’s NetTool is a snack to drive and it works like magic when it comes to tracing network problems. By GREG SWAIN There’s usually not a lot that can go wrong on a small computer network. After all, it either works or it doesn’t. And if it doesn’t, the problem can be quickly diagnosed without specialised test gear. That’s because small networks are really quite simple in concept. Generally, they consist of just a few computers hanging off a single hub or perhaps several hubs linked together. If you strike problems, it’s no big deal 26  Silicon Chip to check each machine for correct setup; ie, checking the installed protocols and checking that other settings, such as TCP/IP addresses, subnet masks and workgroup names, are correct. If you suspect a hardware fault, then a PC itself makes a pretty good piece of diagnostic gear. It can indicate whether or not its network interface card (NIC) is properly installed and it can be used to run diagnostic software. For example, if you are using the TCP/ IP protocol, you can try pinging other computers on the network to see if you get a response (see panel). Another diagnostic tool, Net Watch­ er, lets you view your shared resources and check who is accessing these resources. However, it cannot perform traffic analysis or indicate potential problems. Often, hardware faults are diagnosed by swapping suspect components until the problem goes away. On a small network, it’s really just a matter of using your common sense, plus a bit of trial and error. Large networks When we move to large networks, the trial and error ap­proach is just too time-consuming. There are just too many fault possibilities and other complications to make this approach practical. On a large network, you’ve probably got a DHCP server (for dynamically assigning TCP/IP addresses), primary and secondary WINS servers, a PDC (primary domain controller), a BDC (backup domain controller); SMTP and POP3 mail servers; and perhaps a DNS (domain name server). No; I’m not going to explain what all these services do. This stuff is for the professionals and if you don’t know, you probably don’t need Fluke’s NetTool. Suffice to say, there are lots of things that can go wrong on a large network. How do you know if the DHCP server has lost its marbles and started issuing duplicate IP numbers? Or if there’s a rogue protocol on one or more machines that’s gumming up the works? Or if there are lots of data collisions slowing things down? Or if the WINS server is out to lunch or signal levels are too low? To run these problems to ground, you need a serious network analysis tool such as Fluke’s NetTool. It works with 10Base-T and 100Base-TX networks and can quickly identify a wide range of problems. But its talents don’t end there – hook it into a network and it will eventually identify the major components and services on that network (it also detects Token-Ring networks and phone systems but cannot analyse them). The Fluke NetTool As you’ve probably gathered by now, NetTool is aimed at professional network administrators and installers. It’s a hand­held device that combines cable, network and PC configuration testing into a single unit that’s incredibly easy to drive. The exterior appearance of the NetTool is disarmingly sim­ ple. It has a large LCD screen that displays data in alphanumeric and graphical form; two RJ-45 sockets for accepting network cables; four tricolour LEDs; and six pushbutton switches. These switch­es include an On/Off switch (green); four Navigation but­tons arranged in an oval (up, down, left & right); and a Select button. The tricolour LED indicators (two on either side) show the link and network “health” indication at a glance. For example, the Link/CLSN/ERR LED glows green when link pulses are present, yellow when collisions are occurring and red when errors Fig.1: plug a network cable into both sockets and NetTool shows the cable length and the “wiremap”. Fig.4: the “wiremap” adapter is useful for sorting out cables in a patch cupboard. Fig.2: the cable length can also be quickly determined in single-ended node. Note the “spool” icon. Fig.5: NetTool identifies both straight-through and crossover cables. are occurring. Similarly, the UTIL (utilisation) LED is green when utilisation levels are below 40%, yellow for levels between 40% and 70% and red for levels greater than 70%. The easiest way to operate the device is to hold it in one hand and activate the pushbuttons with your thumb. You turn the unit on or off by holding down the green Power button for two seconds. Cable testing First the simple stuff. Naturally, the NetTool can be used for cable testing. To do this, you simply plug both ends of the cable into the RJ-45 jacks on either side, power up the unit and press Select when AutoTest Flashes on the screen. When you do this, the unit checks both sockets in turn and then displays the results on the LCD in graphical form – see Fig.1. The length of the cable is also shown. This is great for identifying both “straight-through” and “crossover” cables and for quickly determining cable length. It can also quickly in- Fig.3: selecting the spool icon in Fig.2 brings up this display which shows the cable status. Checking Network Cables dicate a faulty cable; eg, if one of the connections is open circuit. A variation on this theme is to use the unit in so-called “Single-Ended Mode”, whereby you plug the cable into only one socket. Again, the unit will quickly determine the length of the cable (Fig.2), after which the cable status can be displayed by navigating to the Spool icon (top, right of the LCD) and press­ing Select – see Fig.3. In this instance, the four twisted pairs are open at 4.9 metres, which is the length of the cable being tested. The single-ended mode is also useful for identifying net­work cable drops. A typical scenario is where you need to identi­fy which cable in a patch cupboard connects back to a given wall socket. This involves plugging the NetTool into the wall socket and testing each cable in the patch cupboard in turn by fitting it with the supplied “wiremap” adapter (basically, a loopback device). When the correct cable is found, the wiremap adapter symbol appears on the LCD (Fig.4). It can then be selected using the navigation buttons, and the The “wiremap” adapter is basically a loopback device that’s used to terminate a cable (via a supplied coupler) or a wall socket. It’s used mainly for cable identification. SEPTEMBER 2000  27 Services, Problems And Health or metres, enable or disable the Auto power-off feature, adjust the display contrast and program in Unwanted Protocols. Unwanted protocols Fig.6: plug the NetTool into a network and it quickly identifies what’s on either end of the cable. It also shows link speed, signal polarity, signal level and the cable connections. Fig.7: selecting the NetTool icon itself brings up the NetTool setup display. This lets you choose the units of measure, adjust the display contrast and enable the auto power-off feature. Fig.8: the Unwanted Proto­cols screen lets you program the NetTool to watch for unwanted protocols on a network. We’ve selected NetBEUI here as a demonstration. Fig.9: the Problem Log lists any network problems that are identified. Fig.10: NetTool is able to identify all protocols that are present on a network. Fig.11: the IP entry can be probed to show the IP protocols that are present. Fig.12: the Key Devices entry shows all the servers, routers and printers that NetTool has found on the network. Fig.13: once it’s found key devices, NetTool can identify their IP addresses and indicate the services offered (eg, POP3). Fig.14: probing the Health entry brings up this display. The two meters indicate the network “health” on either side of the NetTool. Select button pressed to display the internal connections – Fig.5. Service identification This is where NetTool really shines. Plug it into your network, select AutoTest and it immediately determines what’s on the other end of the cable (usually a network hub). Altern­ative­ ly, you can connect the NetTool in “Inline Mode”. This simply involves connecting it between two devices simultaneously, such as a PC and a hub – see Fig.6. This mode is particularly handy for verifying that a PC is communicating properly with a network, for example. Initially, NetTool displays the advertised speed, duplex capability and link configuration. It then eavesdrops on the PC-to-network traffic as the PC attempts to access network resources, after which it shows how the PC is configured and lists any servers, routers or printers used. 28  Silicon Chip As shown in Fig.6, the LCD shows icons at the top for devices and below it a main Menu listing Problems, Protocols, Key Devices and Health. In addition, there are several indicators near the devices that show the link and cabling information, including link speed (eg, 10MB/s or 100MB/s), polarity, signal level, whether the cables are straight-through or swapped, and the duplex setting for each device (whether full or half duplex). This information is all there, at your fingertips, in a matter of moments. So, for example, if you’ve got a dodgy connec­tion, or if signal levels are too low, or if you cannot access a DHCP or email server, you can quickly diagnose the problem. Selecting an icon takes you through menus that are relevant to that particular device. Choosing the NetTool icon, for exam­ple, brings up the NetTool Setup display (Fig.7). Here, you can choose to display cable lengths in feet Fig.8 shows the Unwanted Protocols selection screen. As an exercise, we programmed in NetBEUI as an unwanted protocol and then connected NetTool to our own network which does in fact have NetBEUI installed as a protocol (along with TCP/IP). Sure enough, NetTool immediately flagged a problem at the main menu, by dis­ playing “(1)” after the Problems entry. Each of the menu entries can be selected, to take you through the various “Discovery” screens. Selecting “Problems (1)”, for example, brings up the Problems Log screen (Fig.9). In this case, the unwanted NetBEUI protocol has been correctly identified. OK, that’s a fairly simple example. There are lots of other problems that NetTool can identify and these are broadly broken down into Link Connectivity problems, Health problems, Netware problems (eg, frame mismatches), TCP/IP problems, DHCP problems, Name Resolution problems (eg, DNS server not found or PC DNS server incorrect), NetBIOS problems, Web and Email problems, and Printer problems. If it can’t find the Primary Domain Controller or Backup Domain Controller, NetTool will tell you. If the DHCP server is issuing duplicate IP addresses, NetTool will tell you. If there’s a duplex or speed mismatch, or an unwanted protocol or a du­plicate NetBIOS name, NetTool will show you. If you cannot con­nect to a DNS server, a WINS server or a mail server, NetTool will tell you that too. Protocols and devices Selecting Protocols naturally shows the protocols present on the network and these can then be further probed to show which services are present – see Figs.10 & 11. This feature, together with the ability of the unit to flag unwanted protocols, is handy if you are migrating a network away from certain protocols and want to clear out any old remnants. The Key Devices entry is particularly interesting. This lets you check out all the servers, routers and printers that NetTool has found on the network (Fig.12). In particular, NetTool can identify HTTP, SMTP, POP3, WINS, DHCP, DNS and Netware servers, as well as a router gateway. And if that’s not enough, it can identify the IP address of each one, determine its MAC address and (usually after a while) determine the NetBIOS name as well (Fig.13). By the way, NetTool doesn’t immediately identify all the services on a network when it’s first turned on. Instead, it has to “see” a certain amount of traffic on a network or device before it can supply protocol or health information, or even identify key devices. In that sense, NetTool can be considered as a passive device that sits back and listens to network traffic. It doesn’t actively probe for devices as such. The final entry in the main menu is Health and this brings up a graphical interface showing two meters. Here, you check each side of the link for healthy frames in real time. You can also use the Navigation and Select buttons to change the meters to show utilisation, broadcast traffic, collisions or error levels from either device to which NetTool is connected (Fig.14). PC configuration Troubleshooting an individual PC on a network involves connecting the NetTool between it and the hub and selecting the PC icon. You can then use NetTool to determine the PC’s configu­ration and network health by navigating through the various menus. In particular, the health screen is quite different to before (see Fig.15) and, among other things, indicates short frames, “jabbers” and collisions. Jabbers, by the way, are frames that are longer than the maximum legal The unwanted network protocols feature is handy if you’re migrating a network from one protocol to another or if you just want to find a protocol that might be causing problems. Basic Network Troubleshooting Utilities WANT TO SEE what’s happening on a network? The Net Watch­er utility (Win95/98) lets you view your shared resources and check who is acessing those resources. You’ll find it under the System Tools entry in the Start menu. If it’s not there, you will have to install it using the Add/Remove Programs wizard in Control Panel. YOU CAN quickly check the IP address assigned to a computer (and obtain other useful information) using the Winipcfg utility. It’s started by clicking Start, Run and typing winipcfg in the Open field and clicking OK (NT users should type ipconfig at the DOS prompt). This utility is particularly handy for checking that a PC is correctly obtaining an IP address from a DHCP server, either on a local area network (LAN) or via a dial-up (eg, Internet) connection. Also shown is the address of the DHCP server, the IP address lease period, the subnet mask and default gateway, DNS and WINS server addresses. THE “PING” UTILITY is installed with Win95/98, NT & Windows 2000 and is handy for verifying TCP/IP connections. It’s run from the DOS prompt by typing ping [IP address] or ping [host name], (eg, ping 192.168.0.100 or ping Starbug). The utility sends a series of data packets to the remote computer, listens for a reply and displays the results (see above). If pinging the IP address gives a response but pinging the host name doesn’t, then you may have a name resolution problem (check that the host name matches the entry in the local lmhosts or hosts file). You can also ping your computer’s own IP address (eg, to verify that its TCP/IP installation is working correctly) and use the utility to verify correct entries for default gateways, etc. SEPTEMBER 2000  29 LE ($121.00); and an AC adapter ($51.70). Power for the unit is normally supplied by four AA 1.5V batteries but for heavy-duty use, the NiHM recharge­ ables are the way to go. PC Configuration Conclusion Fig.15: typical health display for an individual PC on a network. It indicates short frames, jabbers & collisions (see text). Fig.16: the link configurat­ ion display shows the signal level and polarity, as well as the link speed and the receive pair. Fig.17: the IP and MAC addresses of the PC are shown, along with its NetBIOS name. This saves checking at the PC itself. size. Just thought that you’d like to know that, so you can sleep tonight! There’s also a new menu item called “Link Configuration” (Fig.16). As before, NetTool tells you the installed network protocols, the PC’s IP and MAC addresses (Fig.17), Netware frame numbers and its NetBIOS name and flags any network problems. Selecting the hub icon brings up a similar selection of menus. A handy feature here is that you can view the network segment ID. We won’t go into all the features here. By now, you should have well and truly got the message – this is a very comprehen­sive and versatile network analysis tool. all, as Fluke’s manual states, “What would we do without a little software in our lives?” Fluke calls the software “NetTool Blaster”. Among other things, it lets you update the internal “smarts” of your NetTool with the latest software (available from Fluke’s website) – see Fig.19. Also included on the CD-ROM are copies of the Quick Reference Guide and NetTool User’s Manual, both in Adobe pdf format. The manuals are easy to follow and the full version even includes a troubleshooting guide. This gives a concise explana­tion of each problem that can be detected by the NetTool and suggests possible remedies. Updating NetTool Optional extras Included with the NetTool is the wiremap adapter, a serial cable adapt­ er, an RJ45-to-RJ45 coupler, a Quick Reference Guide and a CD-ROM. After Naturally, there are a few optional extras available for the NetTool. These include a rechargeable NiMH battery pack ($30.80); a battery charger They say that good things come in small packages and that’s certainly true of the NetTool. It mightn’t look all that impres­sive at first glance but its simple exterior hides some very clever circuitry and software. And as we said at the start, it works like magic. Unfortunately, magic doesn’t come cheap. At $3184.50 (incl. GST) for the NT-IL (NetTool Inline) model review­ ed here, this tool is clearly aimed at professionals. However, if networks are your life (or perhaps the bane of your life), that figure could well be a bargain. It should be in every professional net­work­er’s toolbox. Alternatively, you can buy the NetTool Standard (NT) model for $1864.50. This model provides single-ended testing only but comes with a 50-use trial of the Inline Option. A software upgrade lets you turn an NT model into an NT-IL. Want to find out more on the NetTool? Point your web browser to www. fluke­n etworks.com/nettool; email sales<at>fluke.com.au; or phone Fluke on (02) 8850 3333. You can buy the Fluke NetTool from Fluke, Namlea Data Systems (phone 1300 303 069) or from Anixter AusSC tralia (phone 02 9333 0800). What Would Life Be Without Some Software? Fig.19 (below): pressing the Update NetTool button shown in Fig.18 brings up this dialog box. You can then reprogram your NetTool with the latest software revision. Fig.18: the NetTool Blaster software lets you update to the latest software revision and even download screen shots on the NetTool to your PC (that’s how we got the screen shots in this article). 30  Silicon Chip Above: the NetTool is supplied with a CDROM, a serial cable adapter (for connecting it to a PC), a wiremap adapter, an RJ45-toRJ45 coupler and a Quick Reference Guide. A few optional extras are also available, including an AC adapter, a rechargeable NiMH battery pack and a battery charger. ECTRONICSHOWCASELECT 3990 FULL RANGE $ ELECTROSTATIC Now you can afford the legendary clarity, transparency, depth and precision of an electrostatic speaker. The new Vass ELS-5 is a full range electrostatic speaker, able to faithfully reproduce frequencies from 40Hz-20kHz. • 5 Year Warranty • Wide range of custom finishes. • Individually hand built & tested. 1/42-44 Garden Bvde, Dingley 3172 Pyramid subwoofer Ph 03 9558 0970 Fax 03 9558 0082 separately available email: vass<at>hotkey.net.au MicroZed Computers GENUINE STAMP PRODUCTS FROM Scott Edwards Electronics microEngineering Labs & others Easy to learn, easy to use, sophisticated CPU based controllers & peripherals. PO Box 634, ARMIDALE 2350 (296 Cook’s Rd) Ph (02) 6772 2777 – may time out to Mobile 0409 036 775 Fax (02) 6772 8987 http://www.microzed.com.au Most Credit Cards OK Do you want YOUR product or service showcased to Australasia's most important electronics marketplace? CALL ME: RICK WINKLER on (02) 9979 5644 and let me explain how cost effective the SILICON CHIP ELECTRONICS SHOWCASE can be for YOU! EMC Technologies' internationally recognised Electromagnetic Compatibility (EMC) test facilities are fully accredited for emissions, immunity and safety standards. EMC Technologies Melbourne: (03) 9335 3333 Sydney: (02) 9899 4599 Power line and phone/data filters from AUSTEL and ELECTRICITY AUTHORITY APPROVED Phone-line and mains-borne voltage spikes can damage or destroy your valuable data, computer components and even whole computer systems and networks in less than a heartbeat! Can you afford to be without your system? Can you afford to lose weeks of work or precious records? PowerQwest Technologies can help prevent a disaster with a range of power line and telephone line filters designed to stop voltage spikes before they stop you! Here are two from the wide range available: PowerQwest Zapcatcher PowerQwest Teleswitch Suppresses power line surges and spikes to huge 6500A pk (8x 20s) plus 40dB of mains noise suppression Suppression plus music muting system which cuts power on one outlet (eg to an amplifier) when phone rings.   4x 10A protected outlets 10A thermal circuit breaker Visual warning indication lights PowerQwest Technologies products are available from better computer stores, office products suppliers and department stores. Reseller enquiries to:   4x 10A protected outlets RJ-12 protected phone sockets 10A thermal circuit breaker Phone (02) 9979 4811 Fax (02) 9979 4833 Control devices via your PC parallel port with this Eight-Channel Relay Board by Ross Tester H ave you ever wanted to turn something on or off with a command from your com- puter? Here’s a simple project that does just that – in fact, it will control up to eight external devices via your computer’s parallel port. Most of us have at some stage thought “wouldn’t it be nice if I could get the computer to do X” (fill in your own “X”!) but then have done nothing more because, well, how do you interface a computer with the real world? It’s surprisingly easy! As you would no doubt realise, your computer already “talks” to external devices via its parallel port (more than likely a printer; perhaps a scanner or some other peripheral). It’s that same parallel port which you can use to control external “things”. It’s especially easy if those things only need to be turned on and off. You’ve probably seen parallel port interfaces in the past which have used perhaps half a dozen chips and scads of other components. This one uses a tad less – zero ICs and less than ten other components per “channel”. Normally, to talk to a printer the computer sends various pins in its parallel port high or low at breakneck speed. The various combinations of highs and lows are interpreted by the printer to place ink at a certain position on the page. In this simple interface, we also send various pins high or low – in fact, eight pins (D0-D7). But there’s no combination of pins to worry about. If any of those pins go high, a relay associated with it closes. If the pin is low, the relay opens. With eight output pins, we can control up to eight relays. All control circuits are the same, so our circuit The project is capable of switching eight different devices, with the two larger relays (right end of PC board) being mains rated. The cable underneath which connects to your PC’s parallel port must be a “straight through” D-25 male to D-25 female type, not a crossover cable often used with 25-pin serial ports. 32  Silicon Chip diagram (Fig.1) shows only one (there are seven more just the same on the PC board). When the output pin in the parallel port is sent high by the software, it lights a LED inside an opto-isolator. (The opto-isolator is used to ensure complete isolation between the circuit and your computer). A phototransistor inside the opto-isolator is then turned on, providing bias to another (external) transistor. When this transistor turns on, it energises the relay in its collector circuit. The relay pulls in, switching its contacts over. The relay is a double pole, double throw type (DPDT) so your options for controlling external devices are many. Across the relay coil is a diode, which prevents large induced voltage spikes (from the collapsing relay coil magnetic field) damaging or destroying Q1. There is also a LED/resistor combination which gives a visual indication that the relay is energised. And that’s all there is to the control circuit. There are seven more identical circuits packed onto the PC board with the relay outputs all connected to onboard terminal blocks located around the edge of the board. Actually, they’re not quite identical. Two of the relays (D and E) are mains-rated so can be used to switch 240VAC – if you know what you’re doing, of course. The tracks on the PC board under these relays are also significantly wider, with wider spacings to provide mains isolation. But please, if you’re going to switch mains voltages be very, very careful. For convenience, a 12V regulated supply on board is included, consisting of a bridge rectifier, an electrolytic capacitor and a 12V positive regulator. This supply will operate from about 12-18V AC or 14-18V DC. DC polarity doesn’t matter – the bridge rectifier automatically takes care of that. Construction First check your PC board for any obvious defects. This is rare these days but occasionally there are boards which have tracks missing due to Fig.1: the circuit consists of eight nearidentical sections plus a regulated 12V supply to drive them all. SEPTEMBER 2000  33 Use the PC board pattern (fig.3, above) to check your board etching before starting construction, using the component overlay (fig.2, left). Note that all resistors are mounted “end on” to save space. over-etching, or tracks joined due to under-etching. First components to mount are the resistors. All stand “on end” – and your PC board looks a lot better if all in a group are aligned the same way. Next solder in the eight relay spike suppression diodes, noting which way around they go. The same comment applies to the transistors and LEDs. Solder in the power supply components (again, all polarised) making sure the 3-terminal regulator is soldered far enough off the PC board to allow its U-shaped heatsink to be attached. All of the relays are the next components to mount. Note that the two larger relays, “D” and “E” are placed at one end of the board, while all the rest mount along the edges. Finally (at least as far as the top of the board is concerned) mount the terminal blocks and the 25-pin “D” connector. The D-25 connector has very close pin spacing, so take care that you don’t bridge between its solder pads. The eight opto-isolators mount on the solder side the PC board, not far from the D-25 connector. These look like a small, 4-pin IC with pin 1 marked with a dot. Holding the board solder-side up with the D-25 connector on the left, pin 1 of each opto-isolator is at the top left . Again, pin spacing is pretty tight, so be careful when soldering. That completes the construction side. Give your board a double-check against the component overlay (Fig.2) 34  Silicon Chip and make sure you don’t have any solder dags, bridges or dry joints. The software To drive the relay board, software is required for your PC. This tells the parallel port which pin(s) to take high or low to get the desired result. Incidentally, the software will work with any PC – even that pensioned-off XT clunker! We present the software in two forms. First is an “.exe” or executable file which can simply be run from DOS or a DOS box under Windows. It simply places a graphic representation on screen which shows which outputs are high and low. When you press any of the appropriate keys (A to H) on the keyboard, the corresponding parallel port output pin toggles high or low. This is all very well as a demonstration and to prove your relay board works properly but it is not entirely practical nor useful. What we need is software which can be incorporated into other programs so the ports can be commanded high or low by events, times, actions or other factors. For this reason, we have also shown the Q-BASIC listing from that .exe file. This can be used as is, or sections of it can be added to existing or new software which actually does something useful! Each of the sections of the program are clearly identified so you can use as much or as little as The complete project is mounted inside a plastic case for safety. The red terminal block, connected to relays E and D, can handle mains – if you are doing so, be careful! Supplied PC boards will be silkscreened to make component placement even easier. you want. Alternatively, experienced readers may wish to write their own code to accomplish their specific tasks. DOS box under Windows. Fig.3 shows the screen you should see. When you press any of the keys A through H, the corresponding LED should light and you may hear the relay click over. Touch the same key again and the LED should go out and the relay also drop out. Check each relay/LED one-by-one, on and off, to ensure they’re all working properly. If the LED works but you cannot hear the relay pull in, check with a multimeter across the relay output: the relay may be working fine but it is too soft to hear. Conversely, if the relay works but the LED doesn’t, it’s usually a sure sign that you have mounted the LED back-to-front. If neither work, check the voltage between ground and the exposed end of the appropriate 1kΩ resistor near the D-25 socket. You should get about 1.5V or so with the port high and somewhat less with the port low. If this is OK, check the voltage at the base of its switching transistor. It should switch between (almost) the full supply voltage (say about 11V) and close to zero volts, depending on Checking it out As we said, the executable file is ideal for checking that the relay driver board works as intended. Connect your relay driver board into the parallel port of your PC via a suitable 25-pin male to 25-pin female lead. Note the cable must be wired "straight through” – some cables have crossovers, designed to connect two serial ports together. These are not suitable. In fact, it may be that you don’t even need a cable – the D-25 plug on the PC board could plug directly into the parallel port on some computers, assuming there is room. (In our case we did this but had to remove the D-25 plug nuts as they stopped the plug going right in). Apply power to the board via the two-way terminal block situated right in the middle of the board. Unless you’ve made any mistakes, nothing at all should happen! Now run Rly.exe from DOS or a Fig.3: the screen from the relay.exe software which “drives” the relay interface board. Here keys A, D and G have been pressed to toggle their corresponding I/O ports high. This causes the corresponding relays on the interface board to pull in. Pressing the same letters again will toggle them off again. SEPTEMBER 2000  35 QBASIC LISTING – RLY.BAS (This file and relay.exe are also downloadable from www.siliconchip.com.au) SCREEN 12, 5 a=1 b=1 c=1 d=1 e=1 f=1 g=1 h=1 CLS ppx = 1 OUT &H378 + 0, 0’clear port OUT &H278 + 0, 0’clear port ’*************************************** ’ SCREEN BORDER AND LEGEND LINE (10, 10)-(630, 10) LINE (13, 13)-(627, 13) LINE (630, 470)-(630, 10) LINE (627, 410)-(627, 13) LINE (627, 410)-(13, 410) LINE (627, 413)-(13, 413) LINE (630, 470)-(10, 470) LINE (10, 470)-(10, 10) LINE (13, 410)-(13, 13) LINE (627, 467)-(13, 467) LINE (627, 467)-(627, 413) LINE (13, 467)-(13, 413) ’*************************************** ’ OATLEY LOGO COLOR 9 LOCATE 3, 22: PRINT “ OATLEY ELECTRONICS” LOCATE 25, 24: PRINT “C copyright Oatley Electronics” CIRCLE (187, 390), 10, 1 COLOR 15 LINE (190, 50)-(404, 50), 4 LINE (210, 30)-(210, 70), 4 LINE (195, 35)-(225, 65), 4 LINE (225, 35)-(195, 65), 4 LINE (215, 38)-(205, 62), 4 LINE (205, 38)-(215, 62), 4 LINE (198, 55)-(222, 45), 4 LINE (198, 45)-(222, 55), 4 CIRCLE (210, 50), 7, 3 PAINT (210, 50), 4, 3 CIRCLE (210, 50), 7, 4 ’**************************************** ’ SCREEN TEXT SETUP CIRCLE (35, 260), 7, 15 PAINT (35, 260), 4, 15 CIRCLE (35, 280), 7, 15 PAINT (35, 280), 2, 15 LOCATE 18, 8: PRINT “LO” LOCATE 17, 8: PRINT “HI” LOCATE 6, 31: PRINT “ PC PARALLEL PORT “ LOCATE 7, 31: PRINT “ RELAY INTERFACE “ LOCATE 12, 5: PRINT “RELAY A B C D E F G H “ LOCATE 10, 5: PRINT “I/O No.” LOCATE 10, 16: PRINT “D 0 D 1 D 2 D 3 D 4 D 5 D 6 D 7 “ LOCATE 9, 5: PRINT “PIN No.” LOCATE 9, 17: PRINT “2 3 4 5 6 7 8 9 “ LOCATE 14, 5: PRINT “STATUS” LOCATE 28, 27: PRINT “www.oatleyelectronics.com” ’**************************************** ’ TABLE GRAPHIC LINE (25, 120)-(611, 120), 15 LINE (25, 166)-(611, 166), 15 LINE (25, 200)-(611, 200), 15 LINE (25, 230)-(611, 230), 15 LINE (99, 120)-(99, 230), 15 36  Silicon Chip LINE (25, 120)-(25, 230), 15 LINE (163, 120)-(163, 230), 15 LINE (227, 120)-(227, 230), 15 LINE (291, 120)-(291, 230), 15 LINE (355, 120)-(355, 230), 15 LINE (419, 120)-(419, 230), 15 LINE (483, 120)-(483, 230), 15 LINE (547, 120)-(547, 230), 15 LINE (611, 120)-(611, 230), 15 PAINT (160, 210), 2, 15 PAINT (224, 210), 2, 15 PAINT (288, 210), 2, 15 PAINT (352, 210), 2, 15 PAINT (416, 210), 2, 15 PAINT (480, 210), 2, 15 PAINT (544, 210), 2, 15 PAINT (608, 210), 2, 15 ’**************************************** ’ INPUT ppp: LINE (385, 275)-(405, 275) ‘input underscore LOCATE 17, 23: INPUT “Enter LPT Number, 1 or 2 “; b$ IF b$ = “1” THEN LOCATE 19, 29: PRINT “Current output to LPT1” IF b$ = “1” THEN ppx = &H378 IF b$ = “2” THEN LOCATE 19, 29: PRINT “Current output to LPT2” IF b$ = “2” THEN ppx = &H278 LOCATE 17, 50: PRINT “ “ IF b$ > “2” THEN GOTO ppp io: COLOR 15 LINE (385, 275)-(405, 275) ‘input underscore LOCATE 17, 31: PRINT “ “ LOCATE 21, 32: PRINT “Type ‘x’ to exit”; LOCATE 22, 25: PRINT “All pins are set to L O on exit” LOCATE 17, 22: INPUT “ Enter relay letter”; a$ ’**************************************** ’ ERROR CONTROL AND INPUT SELECT ’IF a$ = “A” THEN GOTO aset1 IF a$ = “B” THEN GOTO bset1 IF a$ = “C” THEN GOTO cset1 IF a$ = “D” THEN GOTO dset1 IF a$ = “E” THEN GOTO eset1 IF a$ = “F” THEN GOTO fset1 IF a$ = “G” THEN GOTO gset1 IF a$ = “H” THEN GOTO hset1 IF a$ = “X” THEN CLS IF a$ = “X” THEN OUT ppx + 0, 0 ‘clear port IF a$ = “X” THEN END IF a$ = “a” THEN GOTO aset1 IF a$ = “b” THEN GOTO bset1 IF a$ = “c” THEN GOTO cset1 IF a$ = “d” THEN GOTO dset1 IF a$ = “e” THEN GOTO eset1 IF a$ = “f” THEN GOTO fset1 IF a$ = “g” THEN GOTO gset1 IF a$ = “h” THEN GOTO hset1 IF a$ = “x” THEN CLS IF a$ = “x” THEN OUT ppx + 0, 0 ‘clear port IF a$ = “x” THEN END SOUND 150, 5 GOTO io aset1: IF a = 2 THEN GOTO aset2 suma = 1 a=2 PAINT (160, 210), 4, 15 GOTO sumall aset2: suma = 0 a=1 PAINT (160, 210), 2, 15 GOTO sumall bset1: IF b = 2 THEN GOTO bset2 sumb = 2 b=2 PAINT (224, 210), 4, 15 GOTO sumall bset2: sumb = 0 b=1 PAINT (224, 210), 2, 15 GOTO sumall cset1: IF c = 2 THEN GOTO cset2 sumc = 4 c=2 PAINT (288, 210), 4, 15 GOTO sumall cset2: sumc = 0 c=1 PAINT (288, 210), 2, 15 GOTO sumall dset1: IF d = 2 THEN GOTO dset2 sumd = 8 d=2 PAINT (352, 210), 4, 15 GOTO sumall dset2: sumd = 0 d=1 PAINT (352, 210), 2, 15 GOTO sumall eset1: IF e = 2 THEN GOTO eset2 sume = 16 e=2 PAINT (416, 210), 4, 15 GOTO sumall eset2: sume = 0 e=1 PAINT (416, 210), 2, 15 GOTO sumall fset1: IF f = 2 THEN GOTO fset2 sumf = 32 f=2 PAINT (480, 210), 4, 15 GOTO sumall fset2: sumf = 0 f=1 PAINT (480, 210), 2, 15 GOTO sumall gset1: IF g = 2 THEN GOTO gset2 sumg = 64 g=2 PAINT (544, 210), 4, 15 GOTO sumall gset2: sumg = 0 g=1 PAINT (544, 210), 2, 15 GOTO sumall hset1: IF h = 2 THEN GOTO hset2 SUMH = 128 h=2 PAINT (608, 210), 4, 15 GOTO sumall hset2: SUMH = 0 h=1 PAINT (608, 210), 2, 15 GOTO sumall sumall: SOUND 600, 2 OUT ppx + 0, suma + sumb + sumc + sumd + sume + sumf + sumg + SUMh GOTO io Parts List 1  PC board, 81 x 117mm, (Oatley Electronics) 6  DPDT mini relays, PC mounting, 12V coil 2  SPDT mains-rated relays, PC mounting, 12V coil 1  D-25 male connector, PC mounting 12 3-way screw terminal blocks, PC mounting 2  3-way screw terminal blocks, PC mounting, different colour 1  2-way screw terminal block, PC mounting 1  D-25 male to D-25 female extension lead, straight through connections, suitable length 1  U-shaped heatsink to suit regulator 1  suitable insulated mounting box or plate (see text) Semiconductors 8  PC814 Opto Couplers 8  C8050 NPN transistors 8  1N4004 silicon diodes 8  5mm LEDs, colours as desired 1  W04 bridge rectifier 1  7812 12V positive regulator Capacitors 1  100µF 35VW PC-mounting electrolytic Resistors (0.25W, 5%) 8  100kΩ 16 2.2kΩ 8 1kΩ whether the parallel port is high or low. The voltage at the collector of the transistor should be the inverse – when the base is high, it should be close to zero (anything less than 1V or so is OK); when the base is low, it should be close to the full supply voltage Safety first! No particular case has been specified for this project; indeed the photo-graphs show the PC board mounted just on the plastic lid of a disposals case, without the case! (It also came from Oatley Electronics, by the way). Regardless of whether or not you plan to switch mains voltages with this project, it should be mounted in a fully insulated (ie plastic/ABS) case because it CAN switch mains voltages. It is essential that the PC board tracks not be exposed because it would be so easy to pick the PC board up and make contact with these tracks – and the tracks under the mains-rated relays could be bitey! SC Where do you get it? This project design and the PC board are copyright (C) Oatley Electronics Pty Ltd. They have available a kit of parts which includes the PC board and all on-board components for $40.00. The cable sells for $8.00. Freight is extra – $6.60 Contact Oatley Electronics at PO Box 89 Oatley, NSW 2223, Phone (02)9584 3563, Fax (02) 9584 3561, email sales<at>oatleyelectronics.com.au, website www.oatleyelectronics.com.au SEPTEMBER 2000  37 SERVICEMAN'S LOG The repair that didn’t make sense It’s the ultimate frustration; the fault has been fixed but the reason for it remains a mystery. Or has it really been fixed? And then there was the classic customer diagnosis: “it’s only the on-off switch”. If only it had been and if only I had a dollar for every time I’ve heard that word “only”. A 1990 Philips Matchline 28 DC2070/20R was brought in by a Mr Holt, who complained that it had no picture. As it turned out, this Belgian-built D-16 chassis uses an ITT digital chipset. After I had removed the back with a TC10 anti-tamper 38  Silicon Chip screwdriver, I found I had to connect external loudspeakers as none was fitted internally. There was no picture or display but turning up the screen (G2) control on the horizontal output transformer produced a fully scanned raster. The sound was OK and I could change the channel and vary the volume on the local control panel. Unfortunately, Mr Holt had not brought in the remote con­trol or the instruction booklet, but using an RC5903 remote from a Philips G110 established that all functions were working except (significantly) there was no contrast control. Also, switch­ ing to AV mode brought the width in and made the raster brighter. However, there was still no sign of a picture. I checked all the voltage rails and all were correct. I checked the I2C digital bus and found activity on both the SDA (Serial Data) and SCL (Serial Clock) rails. I was beginning to suspect that the problem was on the Digital Video Panel (DVP), designated “D”. I had a poor photocop­ied manual for the D16 AG2 chassis but it didn’t accurately represent this model. There were no LED flashing error codes on the front panel. I traced the video as far as the PIP panel “H” and the DVP panel “D”. I also checked the CRT panel “E” to find that there was no signal, so it had to be one or more of the six 40-pin microprocessor ICs on the DVP. Unfortunately, Philips do not regard this module as a serv­iceable item and it is only available as an expensive exchange. However, I felt that I could fix the module, even without a cir­cuit (me and my ego!). First, I established that there was 5V available all over the module and I checked all the coils. Next I checked the two crystals with an oscilloscope. I’m not exactly sure what happened here but while I was checking one of these circuits, the probe I was using slipped and the set died completely. I had to start again from scratch but it didn’t take long to find that the horizontal output transistor TR7455 (BU508AF) was short circuit because of my carelessness. Unfortunately, I had just run out of these transistors and had to put in an order for more. While I was waiting, I decided to remove all six micropro­ cessor ICs from the double-sided DVP module and fit 40-pin IC sockets in their place – a saga in itself. I then reinstalled the ICs in the sockets, my reasoning being that this would make it easier to troubleshoot the module later on if this was where the fault lay. Eventually, the replacement TR7455 transistor arrived and I fitted that as well. This time I had 141V on the collector of TR7455 but the set was still dead and there was no horizontal drive. Furthermore, the Standby LED was flashing, which is error 8 in the service manual and indicates a “+5V, digiboard, POR2” fault. (As far as I can determine, POR2 means “power on reset” and this signal is derived from the power supply and fed to the operation control panel microprocessor 7655 along the A/F 40 line). But despite all this fancy rhetoric, the actual fault turned out to be no 5.25V out of N-channel FET 7308 (IRF520F1). There was 15V on its drain but virtually nothing on its gate or source, either in STANDBY or ON mode. I checked associated tran­sistors 7309 and 7311 for shorts and made Items Covered This Month • Philips Matchline 28 DC2070/20R TV Set. • Philips 20GR102S/75B TV Set. • NEC Model N6361 63cm TV Set. sure they were both switched off but nothing was going to make FET 7308 work. I am never one hundred percent sure when testing FETs with an ohmmeter that I am really proving very much, so I wasn’t sure of its status. I measured the 5.25V rail to find its impedance to be very low – only a few ohms, in fact. I then connected an external power supply on to find it drew nearly 1.9A! I decided to replace the FET but didn’t have an IRF520F1 (100V 9.2A 60W) in stock. However, I did manage to obtain an IRF530 (100V 14A 88W) but this isn’t an insulated type. Neverthe­less, by adding a mica washer and insulating bush, I finally managed to install this as a replacement. This restored the 5.25V rail but the set was still dead with the Standby LED still indi­cating error code 8. I went back to the Digital Video Board module and pulled it out to check it. I should add that this module, like the others, is not hard to install but removing it is an entirely different story. Philips, in their wisdom, have fitted small plastic clips on the edge of the plugs, to make sure that once inserted the modules can’t fall out. The only way to release them is to use a long thin screwdriver to bend them back. Unfortunately, the clips can’t be seen with the modules in position, so it is necessary to probe around until you can feel them. Anyway, there are six 40-pin ICs on this module and I had assumed that all of them were fitted the same way round. As it turns out, the deflection microprocessor IC7251 (DPU2553) is fitted in the opposite direction to the others and, of course, muggins hadn’t noticed. Praying very hard that I hadn’t destroyed this expensive IC, I gingerly refitted it the correct way and refitted the module in the set. This time, the Gods were smiling. Not only did the set fire up smoothly but, believe it or not, there was now a picture! I really didn’t deserve such Introducing direct from USA “Test-Um” TEST GEAR TM From the company that brought you the world-famous ’Lil’ Buttie’ comes an outstanding range of phone and data test equipment... TP100 TELL-ALL TESTER r Identifies phone/data lines r 10Base-T, Token Ring, 100MBit Systems r Built-in battery TT100 TONE TRACER r High sensitivity r With volume control r Headset jack included TG100 TONE GENERATOR r Multi-function - 3 tones r Auto-Off function r Separate “talk” battery Available exclusively through: Call now for more info! Distributor enquiries welcome! Telephone Technical Services Tel (07) 3286 6388, Fax (07) 3286 6399 Shop 2, 55 Shore St West, Cleveland Qld 4163 www.ttservices.com.au SEPTEMBER 2000  39 good luck because all I had done was replace one horizontal output transistor and one 5V switching FET which I had carelessly blown up myself. So how had I fixed the no picture problem? I really don’t know. Perhaps I haven’t – per­haps it’s an intermittent fault condition which will resurface as soon as it goes back to Mr Holt. On the other hand, it’s possible that I fixed a bad solder joint in the process of resocketing all those ICs. Worse for wear Mr Percy’s 9-year old Philips 20GR102S/75B was pretty well clapp­ ed out. Not only did it look as though it had never been turned off, it was also pretty grubby from the kid’s sticky fingers – not to mention the nicotine stains inside and out. Anyway, Mr Percy knew all about it (cough). “Listen mate”, he said, “it just needs a new on/off switch. What’ll it cost?” (cough). Well aware of this presumptuous statement and the conno­tations it held, I innocently asked how he had worked this out. “Well mate, it’s like this” – (cough) – “I have to push it on about six or seven times before it comes on” (cough, cough). Of course, naturally, the switch 40  Silicon Chip must be the problem. I mean, after the fuse, the picture tube and a few dozen other components, what else is there? I mumbled noncommittally that I would have a look and let him know. Naturally, when I tried it, it came on straight away and stayed on. I did this six times and six times it worked perfectly (perhaps I should have done it seven times). The only fault I noticed was that the volume down pushbutton wasn’t working but if the menu was accessed it could be turned down with the other con­trols (he was well aware of this but it didn’t worry him). I removed the back and examined the motherboard. This wasn’t easy because of the dirt, dust and nicotine – plus some salt-air corrosion. However, the one thing that did strike me was how long this set had performed without breaking down – suspect joints were everywhere and it looked as though no work had been done on it since new nine years ago. I guess, this supports the old adage that a car that’s only used by a little old lady to go to church on Sundays can be a bigger bomb than a used taxi! It was pretty clear that the on/off switch was perfectly OK – it operated decisively with no sparks or faulty joints. I phoned Mr Percy with news of my findings. “Are you sure mate?”, he asked. What could I say? It worked for me. Disbelieving, he agreed to let me rework the suspect joints and after running the set for three days he picked it up. Two days later he phoned again and started to get stuck into me. Apparently, it was OK on the first day but it took six activations of the on/off switch on the second day. I was caught in an invidious position. I calmed him down and persuaded him to return the set. As soon as it arrived, I plugged it in and switched it on. It came on straight away. I switched it off and on another eight times while he was there and it all worked perfect­ly. I suggested he check his power point and he suggested I recheck the switch. In the end, we compromised by agreeing he had an intermit- tent start-up problem – though that was a rather too wordy for him. From my perspective, I had already resoldered the suspect joints, so I concentrated on the start-up supply to the horizon­ tal drive. I replaced L5524 (a 1mH coil) and C2523 (6.8µF) with a 10µF capacitor and let the set soak test. However, I was really stumbling around in the dark. In retrospect, I shouldn’t have gone through that resoldering proce­dure first – I should have waited until the fault showed and then made a deduction. Anyway, as luck would have it, eight days later the set wouldn’t come on one morning. I immediately checked the 95V rail to find that it was virtually non-existent (about 1.5V). From experience, this told me where the problem lay. The crowbar protection circuit based on SCR 6641 had been activated. I now knew what to do. With a voltmeter on the 95V rail, I turned up VR3625 and checked the point at which the SCR fired, which turned out to be 97V – only 2V above its operat­ ing point and despite zener diodes ZD6638, ZD6639 and ZD6640 adding up to 102V! Anyway, I changed ZD6640 (30V) for a 33V zener and also sprayed some electrical cleaner on the remaining zeners. This done, I repeated the above procedure and found that the SCR was now striking at over 100V. I then reset VR3625 to give a supply rail of just under 95V. I felt sure that this would fix the problem but, of course, there could still be (unlikely) a fault generated along the OVP (Overvoltage Protection Line). On earlier sets, this came only from pin 9 of the horizontal output transformer. Later sets had an extra transistor (7100) on the 9V rail which checks for exces­sive current (>400mA) drawn by the sound output stage I7020. I left the set, switching it on and off randomly for anoth­er two weeks, despite Mr Percy phoning every day – “surely you’ve fixed the switch (cough) by now, mate?” I would have preferred an even longer time to make sure because what ever happens, I don’t think he will come back – he obviously thinks I know “nuffink”! The local club Our local RSL Club has a lot of TV sets – enough, one would have thought, to employ a full-time technician or at least for them to have a service contract. Tom Purvis, who is the maintenance manager, approached me when I was sipping the cool amber fluid one evening there, un­winding from a hot day with the iron. He mentioned that he had three 63cm NEC sets that had died on him and asked if I would have a look at them. I suggested he remind me in the morning at work and give me all the details then, as I probably wouldn’t remember them overnight. So, next morning, Tom brought in the three NECs. It turned out that they were all model N6361s and all were very grubby and nicotine stained. The N6361 is a 63cm 9-year old set, built in Japan, with a PWC-3517 PC board. This was a very popular chassis, with variants used in a large number of NEC sets. It is also a very reliable model. The reason the first set was dead was because the horizon­ tal output transistor, Q502 2SD1432, was short circuit. Fortu­ nately, I had one in stock and quickly fitted it in. Before switching on, I resoldered the inevitable suspect joints on the diodes and anywhere else that looked suspicious. When I fired it up, the EHT and sound were just coming on when the set died again. Naturally, I was somewhat annoyed when I realised that I had just despatched another expensive transistor to the bin. The replacement 2SD1432 had gone short circuit, which meant that I now had to find the real reason for the fault. I fitted a 60W dummy load and checked that the +130V HT rail was OK. I also checked the timing capacitors, out of cir­cuit, for capacitance, while the shorted turns tester gave the horizontal output transformer the thumbs up. Well, unless anything was lying to me, this shouldn’t have happened. I didn’t have any more 2SD1432s in stock but I did have a BU508AF, which I duly fitted. This time, the picture and sound came on but there were a few slight effects – the set was buzzing/whistling as though it was under some sort of strain. The verticals looked ragged, with intermittent line tearing, and the picture was blooming. The 130V was still spot on, as measured at TP41 – I even put the oscillo­scope on the horizontal drive output (pin 6) of IC701 (M51390ASP) and found nice clean pulses all the way to Q50Z’s collector. Next, I shorted TP2001 to chassis to see if the protector circuit was playing up. Everything looked hunky-dory but the set behaved as though it was mortally sick. I was fortunate in that I also had one of these models as a stock set, so I decided to “borrow” some parts out of it. I swapped the horizontal output transformer and large chunks of power supply but nothing made any difference. And the effect was exactly the same with all three sets. I had ordered some 2SD1432s but then I discovered that the 2SD1433 was a more rugged transistor and was used in later model NEC sets. However, the clincher was that, surprisingly, its price was lower, so I asked that these be supplied instead. When they came in, I fitted one immediately. It blew again in a second or so! That was it – I was out of ideas completely and there were too many contradictions. By now, I felt that the only way to make sense of all this was to go to the source of all knowledge – NEC Technical Support. Their know­ ledgeable engineer was also sur­prised and just as he was about to say he couldn’t help, he said he would ask one of the technicians if he had any ideas. A few minutes later, he came back on the line and said, “Look, this set is pretty reliable and NEC has had very few problems with it, but they have found a few weird faults attributable to C501 – have a look at that”. That was just what I wanted – thank you, NEC. C501 is an electro on the 12V supply to pin 8 of IC701, the jungle IC M531390ASP. Depending on which model is involved, its value varies from 47µF to 470µF. I replaced the capacitor and fitted another 2SD1433 in one of the sets and stood back. It fired up perfectly – all the symptoms had disappeared and the picture was perfect. So, why hadn’t I picked this up? The horizontal drive wave­form out of IC701 should have shown the problem but I hadn’t noticed anything untoward – the waveform had looked very clean. But it is possible that, at switch on, there could be a very short sharp spike or change of frequency which one wouldn’t notice – after all, the trigger and sync separator stages in the CRO (cheapish) can mask a lot of changes. Perhaps it would have been better if I had looked at it on, say, the x 2ms range in­stead of the x 20µs range, at higher volts per division. Anyway, the C501 capacitors were leaky in all three sets and replacing them fixed them all – so, good one, SC NEC! SEPTEMBER 2000  41 PRODUCT SHOWCASE QuickLink Hand-held Scanner: don't type it, swipe it! Hands up if you’ve ever had to type lots of text into your PC from “hard copy”. You’re going to love QuickLink! It’s not much bigger than a high-lighter. But this battery-operated “pen” scans printed text – up to 1000 pages of it – and stores it (2MB inbuilt memory), ready for transfer to your PC or PDA, or even a text-enabled cellular phone. There is no need to be connected to the host – QuickLink is completely portable and transfers of data are made when convenient. Operating under Windows 95/98 or NT, the QuickLink pen transfers data via the PC’s serial port, USB or now even an optional IRDA link directly into any Windows-based application, eg Microsoft Word for text or Excel for data lists. QuickLink is said to be 97% accurate in scanning printed text, and handles bold, italic and regular faces from 6 to 22 point. Just a few of the suggested uses of QuickLink include lawyers scanning precedents, executives collecting information and notes, students making precis of texts, doctors scanning lab reports and patient data, office workers scanning the mail to build a company mailing list – in fact, anyone who needs to convert what they read into any type of computer file. Operating software and a tutorial on CDROM are supplied along with a comprehensive manual and carry case. QuickLink is available through most computer specialists and many department stores. Contact: Wizcom Technologies Australia Pty Ltd Lvl 6, 420 St Kilda Rd, Melbourne Vic 3004 Phone: 1800 09 2000 Fax: (03) 9221 8338 Email: info<at>wizcom.com.au Website: www.wizcom.com.au Now listen here... or there or there or... Y ou may recall the rather clever ADEM Compac security system which we featured in the July issue. Now there’s a mini – no, micro – version which in some ways is even smarter! First, a quick recap. The main claim to fame of the system was that when an intrusion was detected, it called a pre-determined telephone number, reported the intrusion and then turned on a sensitive microphone so you could listen in, just to make sure it was a fair dinkum break-in. 4D Systems, who make the ADEM, told us our story created a lot of interest. But while they were telling us this, they also told us about a new product they’d been working on, the microADEM. Here’s a scenario. The phone rings at two in the morning: it’s the security company telling you the office or shop alarm has gone off. Instead of getting dressed, driving down and walking into who-knows-what, you simply dial, say, the office fax line, punch in a code on your phone keypad and listen in. It’s as quite as a graveyard – you call the security company back, tell them it’s a false alarm . . . and go back to sleep! For anyone on a security company call-out list, what we’ve just described 42  Silicon Chip is pure heaven! Perhaps, though, it wasn’t as quite as a graveyard. Perhaps you could hear the sound of breaking glass, of muffled voices who shouldn’t be there. You ring 000 and the boys in blue respond, surprising your “visitors” in the act. This is just one application for the microADEM. The manufacturers believe it will also find a ready market amongst surveillance professionals (it’s dramatically cheaper than any comparable device on the market) and even business owners who want to ensure that when they’re not there, the things that should be happening are and things that shouldn’t be happening aren’t. Talk about shades of James Bond! In a nutshell, it contains the listening side of the ADEM alarm but with no dialling or intruder detection circuitry. Once again, the microADEM is connected to the ’phone line but of course it can’t dial out (unless it has an optional dialling unit attached which can be triggered by virtually any alarm system, PIR detector, etc ). The microADEM is tiny – just 55 x 60 x 22mm and is cleverly disguised as a dual telephone jack wall box. That’s probably because it is a dual telephone jack wall box! On medication? Remember the pill… Two input digital thermometer Dick Smith Electronics has released an electronic pill box which not only holds the pills, it reminds users when to take them. Equipped with a built-in clock, the battery-operated Pill Box sounds an extra loud beep whenever programmed to do so. It is ideal for people on a multiple-pill per day regime. The Electronic Pill Box is available from all Dick Smith Electronics stores, DSE PowerHouse stores or the DSE mail order service. Jaycar Electronics has released an industrial quality, two-input digital thermometer with a large, easy to read LCD display and wide temperature range. (Jaycar cat QM-1600) The unit is supplied with two detachable K-type thermocouples, is simple to use and will measure temperatures in the range –50°C to 1,300°C. Front panel buttons select the input for display or the meter can be set to show the input temperature differential. The meter has a “HOLD” feature that keeps the current temperature and stops further measurement while the “MAX” function will display and hold the highest temperature measured. Temperature can be measured in °C or °F and the resolution is switchable between 1° and 0.1°. The sampling rate is 2.5 time per second. Contact: Dick Smith Electronics (all stores) Phone: (02) 9937 3200 Fax: (02) 9805 1159 Website: www.dse.com.au TOROIDAL TRANSFORMERS FOR SILICON CHIP AMPLIFIERS 15W CLASS A AMPLIFIER $35.45 80VA for single channel monoblock 240:2x21V/1.9A 160VA for amplifier as published 240:2x21V/3.8A 160VA low flux design + flux band 240:2x21V/3.8A 160VA low flux design + flux band 240:2x42Vct/1.9A $42.50 $65.90 $74.40 ULTRA LOW THD 100W AMPLIFIER 160VA for single channel monoblock 240:2x35V/2.25A + 2x50V/0.1A 300VA for dual channel amplifier 240:2x35V/4.5A + 2x50V/0.1A $50.70 $60.45 500W MONO AMPLIFIER, as published 800VA $134.50 240:2x57V/7A All prices include WST. Freight extra. HARBUCH ELECTRONICS PTY LTD Ph 02 9476 5854 Fx 02 9476 3231 Contact: Jaycar Electronics PO Box 185 Concord NSW 2137 Phone: (02) 9743 5222 Fax: (02) 9743 2066 Email: techstore<at>jaycar.com.au Website: www.jaycar.com.au The only difference between this and a the microADEM double adaptor and then plug your real box (apart from the electronics inside) phone back in. It’s as simple as that! is the 7mm hole in the box top. Under this About the only restriction on location is where is a sensitive electret microphone which is existing equipment (eg, machinery, air conditioners, more than capable of picking up even quite etc) could muffle or mask the sounds you really soft sounds. want to listen in to. The idea of the microADEM is for remote We tried the microADEM out via a mobile audio surveillance. Anywhere there is a phone phone outside the building. Even with computers line, you can plug the microADEM in and listen operating, air conditioning in the background and in. What’s more, this is completely covert – traffic noise outside, a normal-level conversation no-one on the premises has any idea that it’s between two people inside was, as they say in the happening. It’s the stuff some epic Hollywood Inside the microADEM from 4D classics, “clear as crystal”. scripts could be based on! Just to prove the point, the two speakers then Systems. As we hinted at in the scenario, the microADtalked at not much more than a whisper. While EM is operated by punching codes from your telephone keypad. You microADEM couldn’t detect every word, the gist of the conversation can not only remotely listen in, you can change your PIN code remotely, was easily understood. change the way the microADEM answers the phone and change various At the time of going to press, Austel approval for the microADEM other operating parameters. The instructions included are very simple was still pending. 4D Systems believed that this would be ready beto understand. fore this issue of the Contact: Of course, the phone you use can be either fixed or mobile, just as magazine came out. 4D Systems Pty Ltd long as it has a standard tone keypad (which covers probably 99% of The microADEM 3-5 Station Rd, Auburn NSW 2144 phones in use today). sells for $79 (inPhone: (02) 9649 5065 Installation is extremely simple – stick the microADEM to a wall cluding GST but not Fax: (02) 0649 4324 near your existing phone socket using the double-sided adhesive foam including pack & e-mail sales<at>4dsystems.com.au tabs supplied, pull your phone plug from the phone socket, plug in post). SEPTEMBER 2000  43 Rane updates mic/line mixer Rane, distributed in Australia by Jands Electronics, has upgraded its popular MLM 82 mic/line mixer with a new design and features originating from dealers and customers. Each of the MLM 82a’s four mic/line inputs are now assignable to the first, second or both outputs, and a new independent mono switch has been added for each stereo line input. Stereo line gain range has been increased to +12 dB, and removable knobs can now be replaced with individual level control security hole plugs. Like its predecessor, the 1RU mixer provides four balanced studio grade mic/line XLR inputs with phantom power and four balanced stereo TRS inputs. Both outputs can be set to line or mic level. The 82a model is extremely flexible for stereo and/or mono applications in studios, hotels, Contact: churches, schools, Jands Electronics Pty Ltd conference rooms Phone: (02) 9582 0909 and rental sound Fax: (02) 9582 0999 systems. Email: pgrisard<at>jands.com.au New portable device programmer The EE Tools ChipMax from Emona Instruments is a cost effective, high quality industrial-grade device programmer with a standard parallel interface port that is suitable for most programming needs. The state-of-the-art hardware architecture with an on-board FPGA enables ChipMax to support high density EPROMs, EEPROMs, Flash, PLDs, and Micro controllers in DIP (Dual-In-Line Package) without adapters. A builtin hardware current limiting circuit provides protection against improper device insertion, defective chips and (or) operation errors. A standard 40-pin ZIF socket allows ChipMax software to support future devices without changing the hardware circuit. This socket accepts both 300 mil and 600 mil DIP devices up to 40 pins. ­ChipMax is supplied with flexible and easy to use menu-driven software. Contact: Emona Instruments Phone: (02) 9519-3933 Fax: (02) 9550-1378 E-mail: testinst<at>emona.com.au 44  Silicon Chip Audax PC Series Loudspeaker Drivers The PC (Polymer Composite) series of speaker drivers recently introduced by Audax replaces the steel pressed metal series drivers, providing lower driver cost and eliminating magnetic leakage paths in the frame. The highest grade of pure polymer composite has been chosen for the chassis, combining strength, excellent damping qualities and environmental stability (humidity, temperature and shock). The new composite has been subjected to the brutal requirements of the automotive industry and passed all their standards. A new and popular model in this new range is the HP170G0 bass/midrange driver. This features a treated paper cone with a highly damped synContact: thetic rubber surME Technologies round. It is suited to PO Box 50, Dyers Crossing, 2 way compact bookNSW 2429 shelf or tower-style Phone: 02 6550 2254 floor standing speakFax: 02 6550 2341 er systems for hifi or Email: info<at>me-au.com home theatre designs. Website: www.me-au.com New Wollongong Store for Jaycar Jaycar Electronics has opened its latest store in Wollongong, employing up to five local staff in a combination of full time and casual positions. Jaycar brings to Wollongong many years of retail experience and a proven product range covering alarm systems, test equipment, video surveillance, car audio, electrical & electronic tools, wire, cable and accessories. Jaycar is also known for its extensive range of electronic hobbyist kits. Jaycar’s new store is located at 354 Keira St. Wollongong and is open from 9:00am to 5:30pm, 6 days per week. SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au Order Form/Tax Invoice Silicon Chip Publications Pty Ltd ABN 49 003 205 490 PRICE GUIDE- Subscriptions YOUR DETAILS (all subscription prices INCLUDE P&P and GST) Your Name________________________________________________________ (PLEASE PRINT) Organisation (if applicable)___________________________________________ Please state month to start. 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Australia: $A7.70 ea (including p&p by return mail)     Overseas: $A10 ea (inc p&p by air). *BINDERS: BUY 5 or more and get them postage free.   (Available in Aust. only.) ..........................$A12.95 ea (+$5.50p&p). *SOFTWARE: $7.70 per item (project) plus $3.30 p&p per order within Australia, $5.50 p&p per order elsewhere.       (Most software is available free on www.siliconchip.com.au) *ZOOM EFI TECH SPECIAL               $A8.95 inc p&p Aust; $11.95 inc p&p elsewhere. *COMPUTER OMNIBUS: $A12.50 inc p&p Australia; NZ/Asia/ Pacific $A15.95 inc p&p (air); elsewhere $18.95 inc p&p (air). *ELECTRONICS TESTBENCH: Aust. $A13.20; NZ/Asia/Pacific $A15.95 inc p&p (air); Elsewhere $18.95. (All prices incl. p&p). *SILICON CHIP/JAYCAR WALLCHART:         Unfolded (in mailing tube): $A9.95 including p&p (Australia only) – unfolded version not available elsewhere. Folded: $A5.95 inc p&p within Australia; elsewhere $A10 inc p&p. *BOOKSHOP TITLES: Please refer to current issue of SILICON CHIP for currently available titles and prices as these may vary from month to month. SUBSCRIBERS QUALIFY FOR 10% DISCOUNT ON ALL SILICON CHIP PRODUCTS AND SERVICES* *except subscriptions/renewals and Internet access Item Price Qty Item Description P&P if extra Total Price Total $A TO PLACE YOUR ORDER Phone (02) 9979 5644 9am-5pm Mon-Fri Please have your credit card details ready OR Fax this form to (02) 9979 6503 with your credit card details 24 hours 7 days a week OR Mail this form, with your cheque/money order, to: Silicon Chip Publications Pty Ltd, PO Box 139, Collaroy, NSW, MARCH 2001  53 Australia 2097 * Special offer applies while stocks last. 09-00 readout * Digital plus bargraph shows * Display air-fuel ratio to install * Easy in a vehicle auto* Display dims at night Monitor engine air-fuel ratios with this: Mixture Display Monitor the air-fuel ratio of your car’s engine in real-time with this Fuel Mixture Display. It boasts both digital and bargraph displays and can be used as a tuning aid, or when making engine modifications or just to indicate when there are problems. Pt.1: By JOHN CLARKE Your car engine’s air-fuel ratio has a considerable bearing on fuel consumption and air pollution. For this reason, modern cars use an exhaust gas oxygen (EGO) sensor mounted in the ex­haust system to continuously monitor air-fuel ratios and generate corresponding output voltages. This information is then fed to the engine management computer (EMC) which continuously adjusts the mixture to provide optimum power and econ54  Silicon Chip omy, consistent with low exhaust emissions. As can be imagined, if the EGO sensor is not functioning correctly, engine performance suffers and this can lead to very high fuel bills. Conversely, a properly functioning sensor en­sures good engine performance and helps keep fuel costs down – something that’s even more important than ever given the recent petrol price hikes. A system that’s in good nick also minimises air pollution. In modern cars, the combustion products from the engine are made safe by a catalytic converter which is mounted in the exhaust system. Combustion byprod­ucts such as carbon monoxide (CO) are converted to carbon dioxide (CO2), unburnt hydrocarbons to CO2 and water (H2O) and nitrous oxide (NO) to nitrogen (N2) under the action of the catalysts within the converter. However, this only works properly if the air-fuel ratio is held within certain limits. And that in turn is dependent on the EGO sensor. An EGO sensor, by the way, does not last indefinite­ly. Depending on the car, it’s usually a good idea to replace it every 50,000 to 80,000km. Stoichiometric ratio A catalytic converter works best when the air-fuel ratio is such that there is just sufficient oxygen to give complete com­bustion. This is called the “stoichiometric” ratio. It varies according to the fuel used but is generally 14.7:1 for unleaded petrol; ie, the air mass must be 14.7 times the fuel mass. For propane (C3H8), the stoichiometric ratio is a little higher at 15.6 and so more air is required compared to unleaded petrol to ensure complete combustion. Note that the EGO sensor does not measure the air-fuel ratio directly. Instead, it monitors the resultant oxygen (O2) content after combustion and provides a voltage output to in­ dicate whether the mixture is lean, stoichiometric or rich. Fuel Mixture Display The concept behind the SILICON CHIP Fuel Mixture Display is quite simple – it monitors the EGO output signal and, after processing, displays the results on a bargraph and on a digital readout. This digital readout can be calibrated to show the air-fuel ratio for either unleaded petrol or propane. For petrol, the unit is calibrated to display air-fuel ratios ranging from 11.8:1 (rich) to 20.6:1 lean, with the stoichiometric point at 14.7. The corresponding range for propane is from 12.7:1 to 21.5:1, with the stoichiometric point at 15.6. Note, however, that the fuel-air ratio doesn’t remain static while you are driving. Instead, it fluctuates in a rapid rich-lean-rich-lean sequence as the engine management computer (EMC) responds to the EGO sensor’s output. Put your foot down for acceleration and you will immediately see that the mixture is enriched to provide more power. Conversely, under a trailing throttle, the air-fuel ratio “leans off” and again this will immediately be indicated on the displays. Under a constant throttle, the air-fuel ratio should quick­ly settle at a fixed value. This point is leaner than the stoichiometric point, to ensure that emissions are kept low. It’s all made possible by the ECU which continuously monitors the EGO output and controls the fuel injectors to maintain the desired ratio. What sort of figures are we talking about? Well, many late-model engines operate with air-fuel ratios approaching 19.0:1 at constant throttle. As well as relying on the EGO sensor, mixture Main Features • • • • • • • • • • • • • Suits vehicles with Zirconia EGO probes Compact size 3-digit LED readout plus 7-LED bargraph display Dot or bar mode option for bargraph Air-fuel ratio matched for Bosch LSM11 (0258104002) EGO probe Indicates air-fuel ratios from 11.8 to 20.6 for petrol Indicates air-fuel ratios from 12.7 to 21.5 for propane/LPG Fully lean and fully rich air-fuel indication Bargraph display follows the non-linear response of the EGO sensor 13 indication levels in dot mode;, 7 levels in bar mode Fast 220ms update time for bargraph; 440ms for 3-digit display Automatic display dimming 0-1V display for setting up adjustments Note: this device is not suitable for use on cars that run on leaded petrol. If your car doesn’t already have an EGO sensor, you can fit one yourself but the engine must run on unleaded fuel, propane or LPG in order to use the Fuel Mixture Display continuously (leaded petrol poisons the sensor). settings this lean are, in part, made possible by the use of knock sensors. These listen for engine knocking and if it is detected, the ECU retards the ignition timing until the knocking ceases. This allows many engines to run just below the point of knocking, thus significantly boosting fuel economy while cutting emissions. Basic features As shown in the photos, the Fuel Mixture Display is housed in a compact plastic case. Its size and presentation matches that of three previous car projects – the Speed Alarm described in November 1999, the Digital Voltmeter in February 2000 and the Digital Tacho in April 2000. But the similarities don’t end there. As with those earlier designs, this circuit is based on a PIC16F84 micro­controller. This has allowed us to dramatically shrink the parts count and also makes the unit incredibly easy to build. If you look at those earlier circuits, you will notice that they are all quite similar. Most of the hardware modifications involve the input sensor circuitry. The big difference between them lies in the software that’s programmed into the PIC chip. Naturally, we’ve retained the automatic display brightness feature that was built into the previous designs. In bright light, the LED displays are at maximum brilliance so that they can be easily seen. However, as the ambient light falls, the displays automatically dim so that they don’t become distracting. Another feature of the unit is that it’s easy to install. There are just three external connections – two for power and the third to the existing EGO sensor. No EGO sensor? If your car’s engine runs on leaded petrol, it won’t have a factory-fitted EGO sensor. The way around this is to source a sensor from a wrecker and install it in the exhaust manifold yourself. Note, however, that running leaded petrol will soon poison the sensor. As a result, this approach should only be used for tuning purposes, with the sensor then removed and the hole plugged with a bolt of the same thread for everyday running. LED displays OK, let’s see how we have arranged the LED displays to match the output from the EGO sensor. The first thing to realise here is that the output from the EGO sensor is far from linear. Fig.1 shows the output voltage curve from a Bosch zirconium oxide EGO sensor, plotted against air-fuel ratios for both un­leaded petrol and SEPTEMBER 2000  55 LED7 is alight for minimum sensor output. By contrast, the bar mode has only seven threshold points. In this mode, LED4 (the centre LED) covers the central stoichio­metric point for sensor output voltages ranging from 340-650mV (region D). The remaining six LEDs are then used for the rich and lean portions of the display. As the mixture becomes richer, LEDs3-1 progressively come on. Similarly, as the mixture leans off, LEDs5-7 come on. Note that LED4 is on all the time. This makes the bar mode a little unconventional, since it starts from the central LED. However, this approach is perfectly logical. The advantage of the LED bargraph, in either dot or bar mode, is that it can rapidly respond to signal variations from the EGO sensor. This is handy because the EGO sensor output can fluctuate quite rapidly during normal driving. By contrast, the 3-digit readout is set up so that it re­sponds more slowly, so that it can be read. In normal operation, it gives a direct readout of the air-fuel ratio. However, ratios that are less than 11.8:1 or greater than 20.6:1 for petrol are respectively shown as “r” (for rich) or “L” (for lean). Alternatively, the digital readout can be set to show vol­tages ranging from 0.00 through to 1.05V instead of the air-fuel ratio and this is to allow the unit to be calibrated. This is done using two trimpots – one to set the voltage range (span) and the second to set the minimum voltage that can be measured (offset). How the circuit works Fig.1 the above graph shows the output voltage curve from a Bosch zirconium oxide EGO sensor, plotted against air-fuel ratios for both un­leaded petrol and propane. Also shown is the response of the bargraph display as the EGO output varies, for both dot and bar modes. propane. Also shown are the corresponding Lambda (λ) values which are calculated by dividing the air-fuel ratios by the stoichiometric value. This means that a Lambda of 1 is at the stoichiometric point. Fig.1 also shows the corresponding response of the LED bargraph display as the EGO output varies, for both dot and bar modes. First, the dot mode – this has either one or two LEDs lit at any time, giving 13 separate display 56  Silicon Chip points. The stoichiomet­ric point at 600mV is indicated by the central indicator LED4, which lights over the range indicated by “G” on the curve. As the voltage climbs towards the rich end, both LEDs 3 & 4 light, then LED 3 lights on its own, then LEDs 2 & 3 together and so on until only LED 1 is lit at the end of the range (ie, maxi­mum voltage). A similar sequence of events occurs as the mixture leans off, until only Fig.2 shows the circuit for the Fuel Mixture Display. IC1 is the PIC micro­ controller which forms the basis of the circuit. It accepts an input from the EGO sensor via op amp IC2a and drives the LED displays. IC2a functions as an inverting comparator. As shown in Fig.2, the signal from the EGO sensor is applied to its pin 2 input via a filter circuit consisting of a 1MΩ resistor and a 0.1µF capacitor. Note that the resistor is made large to reduce transient loading on the EGO sensor. In fact, the current from the EGO sensor must be at less than 1µA so that its output voltage (and thus the engine performance) isn’t affected. In operation, IC2a compares the SEPTEMBER 2000  57 Fig.2: the PIC microcontroller (IC1) processes the input signal from the EGO sensor (via IC2a) and drives the 7-segment LED displays and the LED bargraph. Q6, D1, D2 & REF1 provide a voltage offset for pin 3 of op amp IC2a, while IC2b & LDR1 automatically vary the display brightness, so that they don’t appear too bright at night. Fig.3: here are the assembly details for the two PC boards. Resistor R1 is installed if you want the bargraph to operate in bar mode and is left out of circuit for dot mode operation. Take care to ensure that you don’t get the transistors mixed up. sensor voltage at pin 2 with a DC voltage at its pin 3 input. This DC voltage is derived by applying a pulse width modulated (PWM) square-wave signal from the RA3 output of IC1 to an RC filter/divider circuit. As a result, pin 1 of IC2a switches low when ever the vol­tage on its pin 2 input is greater than the voltage on pin 3. This signal is then fed via a 3.3kΩ limiting resistor to the RB0 input of IC1. The resistor limits the current flow from IC2a when its output swings high to +12V, while internal clamp diodes at RB0 limit the voltage on this pin to 5.6V (ie, 0.6V above the supply rail). A-D converter Among other things, IC1 performs analog-to-digital (A/D) conversion. This converts the signal on its RB0 input into a digital value which is then used to drive the LED dis­plays. As mentioned above, the output at 58  Silicon Chip RA3 produces a PWM signal and this operates at 1953Hz with a wide-ranging duty cycle. A high output from RA3 is at 5V while a low output is at 0V. VR2, the 180kΩ resistor and the 0.1µF capacitor filter this output to produce a DC voltage, while the 100kΩ and 1kΩ resistors from pin 3 to ground form the bottom of the voltage divider. In practice, VR2 is set so that it divides the RA3 output by 3.9. This means that if the duty cycle is 50% (ie, a square wave) the average at RA3 will be 50% of 5V or 2.5V. As a result, the voltage at pin 3 will be 2.5/3.9V, or 0.64V. This will vary either up or down, according to the duty cycle. The A-D conversion is as follows: initially, the RA3 output at pin 2 of IC1 operates with a 50% duty cycle and this sets the voltage at pin 3 of IC2a to 0.64V. At the same time, an 8-bit register inside IC1 has its most significant bit set high so that its value is 10000000. This 50% duty cycle signal is produced at a frequency of 1953Hz for about 8ms, after which the comparator output level (pin 1 of IC2a) is monitored by the RB0 input. Pin 1 of IC2a will be low if the sensor voltage at pin 2 is above 0.64V and high if it is less than this value. If the sensor voltage is less than 0.64V, the pulse width modulation (PWM) output at RA3 is reduced to a 25% duty cycle to produce an average of 1.25V and thus 0.32V on pin 3 of IC2a. The internal register is now set to 01000000. Conversely, if the sensor voltage is above 0.64V, corre­sponding to a low comparator output, the RA3 output is increased to a 75% duty cycle to provide an average of 3.75V. The register is thus set to 11000000, with the most significant bit indicating the 2.5V 50% duty cycle and the next bit indicating the 1.25V 25% duty cycle. Adding the two bits gives us the 3.75V (75%) value which, after division by 3.9, gives 0.96V on the pin 3 input of IC2a. The comparator level is now checked again after about 8ms. The microcontroller then adds or subtracts a 12.5% duty cycle value (0.625V at RA3 or 0.16V at pin 3 of IC2a) and this is then compared with the input voltage again. If the sensor voltage is higher than the PWM waveform, the internal register is now set to X1100000 (where X = 1 or 0 as determined by the first operation). Conversely, if the sensor voltage is lower than the PWM voltage, the register is set at X0100000. This entire process is repeated for eight cycles, the microcontroller adding or subtracting progressively smaller voltages to pin 3 of IC2a. At each step, successively lower bits in the register are set to either 1 or 0 to obtain an 8-bit A-D conversion. The A-D conversion has a resolution of 5mV (0.005V) at the least significant bit. There are also 256 possible values for the 8-bit register, ranging from 00000000 (0) to 11111111 (255). However, in practice we are limited to a range from about 19 to 231. That’s because the software requires a certain amount of time to process the results in IC1 and produce the next waveform at the RA3 output. As a result, the measurement range is from about 95.5mV to 1.16V. However, by applying a slightly negative offset voltage to the pin 3 input, we can effectively cancel out the 95.5mV minimum so that it can be set at 0V. This then allows the comparator to measure from 0V to 1.16V - 95.5mV; ie from 0-1.06V. Following the A/D conversion, the 8-bit register value is converted to the value required for the display using a lookup table. In practice, separate tables are used for the air-fuel ratio display and the two modes for the bargraph. These lookup tables can be easily modified if required. Negative offset voltage The negative offset voltage applied to pin 3 of IC2a is derived using voltage reference REF1, diodes D1 & D2 and transis­tor Q6. Let’s see how this works. In operation, Q6 is driven by the RA4 output of IC1 which incidentally, also drives switching transistor Q1 which controls the LED bargraph. When RA4 is low, Q6 is off and so capacitor C1 (10µF) charges to the +12V supply via a 1kΩ resistor and diode D1. Conversely, when RA4 subsequently goes high, Q6 turns on and connects the positive terminal of C1 to ground. As a result, the negative terminal of C1 goes to -12V and this charges capacitor C2 via diode D2. Table 1: Capacitor Codes    Value IEC Code EIA Code 0.1µF   100n   104 15pF   15p   15 The display board (top) carries the three 7-segment LED displays, the bargraph and the LDR. It plugs into the microcontroller board above, thus eliminating wiring connections between the two. Table 2: Resistor Colour Codes  No.   1   1   1   1   1   2   2   2   1   4   8   1 Value 1MΩ 180kΩ 100kΩ 12kΩ 10kΩ 3.3kΩ 1.8kΩ 1kΩ 1kΩ 680Ω 150Ω 10Ω 4-Band Code (1%) brown black green brown brown grey yellow brown brown black yellow brown brown red orange brown brown black orange brown orange orange red brown brown grey red brown brown black red brown brown black red brown blue grey brown brown brown green brown brown brown black black brown 5-Band Code (1%) brown black black yellow brown brown grey black orange brown brown black black orange brown brown red black red brown brown black black red brown orange orange black brown brown brown grey black brown brown brown black black brown brown brown black black brown brown blue grey black black brown brown green black black brown brown black black gold brown SEPTEMBER 2000  59 resistor is present, then that input will be pulled low. The software reads the inputs to determine whether they are high or low and sets the display mode accordingly. It then resets RB1, RB3 & RB4 as outputs so that data can be presented to the LED displays. Display dimming These two photos show how the two boards are married together, with the pin headers on the display board plugging directly into the 7-way sockets on the microcontroller board – see also Fig.4. This process is repeated at a rapid rate, so that about -6V is maintained on the negative terminal of C2. This voltage is ap­plied via a 3.3kΩ resistor to REF1 which produces a fixed -2.49V and this in turn is divided down by a 12kΩ resistor, VR3 and the 1kΩ resistor to ground to give the required 95.5mV negative offset. LED displays The 7-segment display data from IC1 appears at outputs RB1-RB7, as does the data for the LED bargraph. These outputs direct­ly drive the LED display segments and the bargraph LEDs via 150Ω current limiting resistors. As shown, the corresponding display segments are all tied together. In addition, the cathodes of the seven LEDs are each tied to a display segment. In operation, only one 7-segment LED display or the bargraph is on at any instant but because they are rapidly switched in sequence, they appear to be continuously lit. This technique is called “multi­ plexing” and it involves individually switching outputs RA0-RA4 low and then high again in sequence to control 60  Silicon Chip switching transistors Q1-Q4. Q1-Q4 in turn control the LED displays. For example, when RA0 is switched low, Q4 turns on and applies power to the common anode connection of DISP3. Any low outputs on RB1-RB7 will therefore light the respective segments in the display. RA0 is then switched high again and RA1 is switched low to drive Q3 and DISP2, after which it’s the turn of RA2 and RA1. Display modes Resistors R1, R2 and R3 are used to select the various display mode options. When installed, they respectively tie the RB1, RB3 and RB4 lines low. R1 determines whether the bargraph operates in bar or dot mode; R2 sets the display mode to volts or air-fuel ratio; and R3 determines whether the air-fuel ratio is for propane or unleaded petrol. Each time power is applied to the circuit, the software sets RB1, RB3 & RB4 as inputs with internal pullup resistors. Each pullup resistor will hold its corresponding input pin high if there is no external resistor to ground. Conversely, if an external IC2b is used to control the display brightness. This op amp is connected as a voltage follower and drives buffer transistor Q5 which in turn controls the voltage on the emitters of the display driver transistors, Q1-Q4. When the ambient light is high, LDR1 is low resistance and so the voltage on pin 5 of IC2b is close to +5V. This means that the voltage on Q4’s emitter will also be close to +5V and so the displays operate at full brightness. As the ambient light falls, the LDR’s resistance increases and so the voltage at pin 5 of IC2b falls. As a result, Q5’s emitter voltage also falls and so the displays are driven at reduced brightness. At low light levels the LDR’s resistance is very high and the voltage on pin 5 is determined by VR1. This trimpot sets the minimum brightness level. Clock signals Clock signals for IC1 are provided by an internal oscilla­tor circuit and this operates in conjunction with 4MHz crystal X1, between pins 15 & 16. Also included in the clock circuit are two 15pF capacitors. These ensure correct loading so that the oscillator starts reliably. In operation, the 4MHz crystal frequency is divided down internally to produce separate clock signals for the microcon­troller operation and for the display multiplexing. Power Power for the circuit is derived from the vehicle’s +12V ignition supply. This is fed in via a 10Ω resistor which, togeth­er with the 47µF and 0.1µF capacitors, provides decoupling. Zener diode ZD1 is included for transient protection – it limits any spike voltages to 16V and also protects against reverse supply connections. The decoupled supply rail is fed to REG1 to derive a +5V rail. This is then filtered and used to power IC1 and the LED displays. IC2 and the voltage offset circuit are powered directly from the decoupled +12V ignition supply. Software OK, that completes the circuit description. In reality, the hardware only forms half the picture. The other half is locked up inside the microprocessor which performs all the complicated stuff under software control. Do you REALLY want to know how the software works? Do you? We won’t go into the details here because we don’t have space. If you must know, then you’ll find the source code posted on our website. Construction You really don’t need to concern yourself with the software to build this circuit. Instead, you simply buy the programmed PIC chip and install it like any other IC. Fig.3 shows the assembly details. This mainly involves building two PC boards – a microcontroller board coded 05109001 and a display PC board coded 05109002. Once assembled, these two board are stacked together in piggyback fashion using pin headers and cut down IC sockets. This technique eliminates inter-board wiring since the connections are automatically made via the pin headers. Before starting assembly, check both boards for shorts between tracks, open circuits and undrilled holes. Note particu­larly that two holes are required in the display PC board to provide screwdriver access to trimpots VR1 and VR2 on the proces­sor board. These holes are located just below DISP3 and to the left of VR3. The microcontroller board can be assembled first. Begin by installing the wire links, then install the resistors. Table 2 lists the resistor colour codes, although it’s a good idea to also check them using a digital multimeter. Note that the seven 150Ω resistors are mounted end-on as shown. Trimpots VR1 & VR2 can go in next, followed by a socket to accept IC1 (taking care with its orientation). IC2 is soldered directly to the board – install this now, followed by zener diode ZD1 and transistors Q2-Q5. Be very careful here, because Q5 is the odd man out. It’s an NPN BC337 type, whereas Q2-Q3 are all PNP The whole assembly fits neatly into the smallest available plastic utility box and matches several previous car projects based on PIC microcontrollers. LDR1 should be mounted so that its face is about 3mm above the LED displays. BC327s. Mix them up and you’ve got problems. Regulator REG1 must be mounted as shown, with its metal tab flat against the PC board and with its leads bent at rightangles so that they pass through the PC board holes. Make sure that the hole in its metal tab lines up with the matching hole in the board, as this has to later accept a mounting screw. The capacitors can now be installed. Note that the two electrolytic capacitors are mounted horizontally, across the regulator’s leads; ie, their leads should be bent at right angles before they are installed. Note also that these capacitors are polarised, so be sure to mount them with the polarity shown. Crystal X1 mounts horizontally on the PC board but can go in either way around. It is secured by soldering a short length of tinned copper wire to one end of its metal case and to a PC pad immediately to the right of Q3. The three 7-way in-line sockets are made by cutting two 14-pin IC sockets into inline strips. Use a sharp knife or a fine-toothed hacksaw for this job and clean up the rough edges with a file before installing them on the PC board. Finally, install three PC stakes at the external wiring positions (sensor, +12V & GND). Once they’re in, trim these stakes on the parts side of the board so that they cannot short against the display board later on. Display board assembly As before, install the wire links and resistors first but only install R1 if you want the bargraph to operate in bar mode. This done, install the three 7-segment LED displays with their decimal points at bottom right. The LED bargraph can also be in­stalled at this stage – it mounts with its pin 1 (indicated by the bevelled edge) towards transistor Q1. The remaining parts can now all be installed, noting that D1 and D2 face in opposite directions. The two 10µF capacitors are mounted flat against the PC board, while LDR 1 should be in­stalled so that its top face is about 3mm above the displays. The three 7-way pin headers are installed from the copper side of the PC board, with their leads just protruding above the top surface. You will need a fine-tipped iron to solder them in. It will also be necessary to slide the plastic spacers along the pins to allow room for soldering, after which the spacers can be pushed back down again. That’s all we have space for this month. Next month, we will complete the assembly and describe how the unit is installed and calibrated. SC SEPTEMBER 2000  61 LA-CRO C’est Magnifique It’s a CRO, signal generator, frequency analyser, logic analyser, chart recorder and more, all in one compact package. By PETER RADCLIFFE* Electronics project work can be very frustrating for many students due to a lack of test equipment. Unfortunately, the simple solution of buying lots of equipment is just too expensive for many institutions, so that’s not the answer. And even where equipment is readily available, students usually cannot take it home to “play” with in their own time. At the Department of Computer Systems Engineering at RMIT (Melbourne), we graduate some 250 engineering Peter Radcliffe is a Senior Lecturer at the School of Electrical and Computer Systems Engineering at RMIT. 62  Silicon Chip students each year who must be competent in electronics design, communications sys­tems design, and of course computer systems and software design. And in common with many other institutions, we have found it a struggle to keep our high-quality project work going, in part because equipment is so expensive. More importantly, we have found that students learn much more when they can do laboratory and project work at home. They can fiddle around and try things, come back to it later if they are stuck, and spend as much time on the equipment as they wish – things that are impossible in a 2-hour lab session. Unfortunate­ly, very few students can Fig.1: this screen grab shows an AM signal from the inbuilt signal generator (green trace) and the resulting demod­ulated signal (pink trace) obtained using a diode, resistor and capacitor. Fig.2: the frequency spectrum for the AM signal (green) and the demodulated signal (pink). Note the carrier and sidebands around 10 harmonics, and the DC offset and demodulated signal around the first harmonic. afford the equipment necessary to work at home – until now, that is. My solution to this dilemma has been to create “LACRO”. Basically, the aim was to keep it as inexpensive as possible while providing many useful test instruments, all in one easily-carried package. Of course, it’s speed is limited (the sampling rates are just 1µs digital signal and 1.2µs for analog) but it’s affordable and is sufficient for most purposes. Physically, the device is built into a metal diecast case which makes for a very rugged assembly indeed. In fact, it’s virtually bullet-proof! The actual dimensions are 160 x 150 x 45mm (W x D x H), so it slots easily into a briefcase or carry bag. Power comes from a 12VAC plugpack supply. (4) A signal generator which includes both AM and FM modu­lation facilities. There are two outputs: ±1V and ±10mA. (5) A 2-channel chart recorder that saves to disk as it samples. Measurements include average, peak, RMS, frequency and period. The logic functions include: (1) A logic analyser with trigger and sampling rates up to about 1MHz. (2) A logic chart recorder. (3) A logic tester in which eight channels of data can be edited. The eight outputs can drive the circuit under test and the eight inputs captured. All 16 waveforms can then be displayed on screen. Where’s the PC? Other features As you’ve no doubt gathered by now, LA-CRO isn’t a standa­lone device. Instead, it plugs into the parallel port of a PC and works with an accompanying software program that runs under anything from Windows 3.1 to Windows 2000. In operation, the software generates virtual instrument panels direct­ly on the PC’s monitor. You don’t need fancy hardware to run the LA-CRO software and an old PC can be pressed into service if you have one spare. The minimum system requirements are a 33MHz 486 and 3MB of hard disk space. As for the RAM required, well that depends on the operating system that you’re running. The software has been designed to wring as much as possible from the hardware. The result is a unit that, although modest in speed, has a remarkable range of functions (both analog and digital). We’ll take a look at the analog functions first. These include: (1) A dual-channel digital storage CRO with a maximum reso­lution of about 1.2µs. (2) A frequency analyser, with frequency spectrum of the signal displayed in terms of harmonics of the fundamental fre­quency. (3) Frequency response analysis from about 25Hz to 100kHz. LA-CRO’s talents don’t end with the features listed above, though. There are lots of other features, as follows: (1) LA-CRO can supply +5V and -5V rails at 300mA to power circuits under test. (2) An output called “GO” goes high, from 0V to +5V, The LA-CRO circuit board is mounted on a metal diecast base, with a cover then fitted over the top. It connect to the PC via a standard printer cable. SEPTEMBER 2000  63 Fig.3: the chart recorder has been used here to capture the turn-on transients of an amplifier. Fig.5: eight user-defined outputs can be used to drive a circuit and eight inputs captured using the Logic Tester. Fig.4: this relay operation was uncovered using the oneshot storage capability of the CRO and the GO output for driving the relay. The green trace shows that the relay switched some 8ms after being energised. The coil current (red trace) took about 3ms to build and has some ripple as the armature closes against the coil. Fig.6: the digital chart recorder can set any of the eight digital outputs and record the responses of the 12 digital inputs and the X & Y inputs. Notice that the X and Y threshold voltages can be individually set by entering in the desired values, and you can set the element width and sampling rate. three samples after any CRO sampling starts. This can be used to drive devices at currents up to 300mA, including relays and small light bulbs. GO can be extremely useful when it comes to stimu­lating transient events. (3) Except for the AC/DC selection, all controls, including gain, operate from the screen. (4) In single-cycle mode, the CRO automatically sets the timebase so that exactly one cycle is displayed. (5) The data on most screens can be saved as a .CSV file that can subsequently be loaded into any spreadsheet. (6) The eight digital outputs and 12 digital inputs can be directly controlled from the LA-CRO software or from C and C++ programs that you write. (7) The signal generator can load an arbitrary signal shape from a text file. For instance, one of the examples provided with LA-CRO spells out “MUM” on the CRO! By the way, the LA-CRO Help file is quite extensive and is context sensitive. Each control is fully explained and its limitations stated. The analog portion of LA-CRO is accurate to about seven bits which is adequate for most purposes. A close inspection of the sinewave will show a little noise but the distortion is under 1%. Of course, the modest sampling speeds (1µs digital and 1.2µs analog) mean that you won’t be debugging your Pentium PC or RF circuits with LACRO. On the other hand, these sampling speeds are more than adequate for audio work and digital inter­faces like serial EEPROMs, data links and slower microprocessors. In many cases, LA-CRO may be the only test instrument you need as it can power a circuit, provide analog and digital in­puts, and then measure the analog or digital outputs and display the results on the monitor. 64  Silicon Chip External connections LA-CRO connects to external circuits using three 34way IDC connectors. The CRO inputs and signal generator outputs are most easily connected by test clips (which come with the full package). Test clips are less expensive than BNC connectors and being small, they can often connect to parts of the circuit Fig.7: the ±10mA output and the XY mode are used here to show the voltage-current characteristics of a zener diode. that would be would be impossible to reach with standard BNC leads. On the other hand, the digital inputs and outputs are prob­ably best connected using 34-way IDC cables. These can be fitted with connectors so that they simply plug into the IDC header pins, or you can solder the relevant leads to the pins. Although 34-way IDC cables can be purchased new, you can save money by purchasing then secondhand. These are the same as the floppy disk drive cables used in PCs and can often be found in the “disposals” boxes at electronics and computer stores. Alternatively, you can scrounge them for nothing from junked PCs. If you need to make up your own leads, IDC connectors are quite cheap and can be purchased in both solder and wire-wrap versions. Driving LA-CRO Connecting LA-CRO to your computer and installing the soft­ware is dead simple. The software comes on two floppy disks and is installed by double-clicking the setup icon (the procedure is a bit more complicated for Windows 3.1 but it’s all explained in the instructions). A standard printer cable is used to connect the hardware to the PC’s parallel port. Note, however, that most PCs have several EPP (enhanced parallel port) modes and not all these will work with LA-CRO. This means that, in some cases, it might be necessary to enter the BIOS setup and change the printer port setting. When you load the software, a display window appears with buttons for all the instruments. After that, you can go to the required test in­strument by clicking its button. The various screen grabs (Figs.1-9) show just some of the virtual instrument panel displays under actual measurement conditions. One interesting feature is that either an HC240 or HCT240 logic input buffer can be used in LA-CRO, to cater for CMOS or TTL voltage thresholds respectively. An HC240 chip is supplied and this (or an HCT240) is installed in socket U1, adjacent to the voltage regulator. The digital portions of LA-CRO can be driven directly from C or C++ programs. This raises some interesting possibilities. Windows NT and Windows 2000 block any Fig.8: there are lots of options available for the signal generator, including AM and FM modulation. Fig.9: the “Help” file is context sensitive. Click on the Help button for any of the instruments and the Help file shows you how to use it. attempt to use IO port access so the LA-CRO program must be running to enable IO access. Conversely, under Windows 3.1, 95 or 98, there is no need to run the LA-CRO software to access the IO ports. Availability Two versions of LA-CRO are available: a student version consisting of a fully-assembled PC board for $220.00 and a full package with case, plugpack, test clips and software on floppy disk for $330.00. You can find out more, including how to order, by pointing your web browser to www. techno-centre.com In fact, the Techno-Centre website is worth visiting in its own right as it has lots of good information on hardware, soft­ware and business issues. Take SC a look for yourself. Find Out More About RMIT LA-CRO is now used very successfully in the School of Elec­trical and Computer Systems Engineering at RMIT (Royal Melbourne Institute of Technology). To find out more about RMIT, visit their website at www.rmit.edu. au and check out their web-based “Open Day” for more projects and details of the university courses. SEPTEMBER 2000  65 SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au the easy way into electronics This month we introduce a new way of working with electronic circuits – using Protoboards. They enable you to put a circuit together quickly without having to solder components into a PC board. You can make changes very quickly and when you’ve had your fun, you can pull it all apart and use the components for something else. A ctually, there is nothing new about protoboards. They have been used by engineers and technicians for making prototype circuits for around 20 years or more. In fact, that’s how most of the circuits published in SILICON CHIP begin life, as a “lash-up” on a protoboard. We have them in all sizes and have used them to “bread-board” circuits with as many as 40 ICs in some cases. So we thought it was high time that we described the concept to all our readers so that they (you) can enjoy their advantages. So what is a protoboard? As you can see from the photo, it is a plastic board with a multitude of holes in it into which you can plug ICs, transistors, diodes, resistors, capacitors and a lot of other components. The holes are internally connected in vertical (columns) and horizontal lines (rows). Protoboards are particularly useful for lashing up circuits with dual inline (DIL) ICs but are equally useful for circuits involving small signal transistors or a mixture of ICs and discrete components which is what most circuits tend to be. Fig.1 shows how the holes in a typical protoboard are connected together. The internal metallic connecting strips are shown in light blue. As you can see, there is a central horizontal channel and the ICs are plugged in to straddle this. Each pin will then be plugged into a column connecting strip, each connecting five By LEO SIMPSON SEPTEMBER 2000  69 holes together. So if you have an IC plugged in, you can have four components or leads connected to each pin. Then there are two rows of connecting strips at each side of the protoboard and these are broken in the centre by the “W” trademark. These eight strips are used for making positive and negative supply connections. As we will see later on, having the supply connectors broken in the centre makes it possible to have up to eight separate supply rails or decoupled supplies and so on. Don’t worry too much about the variations that are possible. Just remember that a protoboard of this style is broken up into a lot of vertical column connector strips for connecting to each pin of ICs and then there are long row strips which provide for power supply connections. The small 8-pin, 14-pin and 16-pin ICs are not the only ones that can be plugged in. You can also plug in any larger dual in-line IC whether it be a 40-pin job or larger, although since it will be wider, you will not be able to access all five holes on each column connecting strip. What size to buy? Protoboards, sometimes called “prototyping boards” or “electronic breadboards”, come in all shapes and sizes. What size is the best to buy? In our experience, you will probably want one which can accommodate up to about six to eight 16-pin ICs in a single line. Anything more than that and you are probably well acquainted with protoboards and already have one or more on your workbench. This rather tatty protoboard shows part of a circuit currently under development in the SILICON CHIP workshop. The beauty of protoboards is that you can make circuit changes quickly and easily, and without soldering. So to introduce this series of articles on protoboards, we have decided on a particular type which is readily available from parts retailers and which has the right combination of features. The one we have decided upon is the Wish WB-102 protoboard which is available from Dick Smith Electronics (Cat H-4044) at $18.63. Other retailers will have identical or similar breadboards available. For example, Jaycar have the WBU-202. It is a little smaller than the WB-102 model and it does not have the facility for splitting the supply lines but it will accommodate the same number of ICs. Current and voltage ratings Before we go too far with proto-boards, we need to talk about the current and voltages that they can handle. In a word, “low”. They can’t handle high voltage (because there is a danger of flashovers” across the various connecting strips. And they can’t handle high current because the connecting strips are quite thin. Don’t even think about connecting up a protoboard circuit which runs directly from the 240VAC mains supply. This would be very dangerous as the closely-spaced connector strips would flash over between themselves or to the metal baseplate which we will come to Fig.1: This diagram shows how the holes in a typical protoboard are connected together. The internal metallic connecting strips are shown in light blue. 70  Silicon Chip later. Plus, the whole circuit would be a death-trap! Nor can you plug in components which have thick connecting pins or big solder lugs. This rules out most power transistors and Mos-fets, rectifier diodes, large electrolytic capacitors, wire-wound resistors and so on. The rule of thumb is that if you have to force a component lead in, it is too thick. However, you can still use all these components with protoboards, provided you solder thin connecting wires to each thick pin or lug. You’ll get the idea as we go along. By the way, if you are silly and do jam a thick component into a protoboard hole, you will find that, forever after, that connecting strip will then make poor contact with component leads. You should then mark those holes with a Texta-colour pen to highlight This is our sample protoboard mounted on a baseplate which has provision for pots, terminals and other hardware. The chaser circuit has been wired up with jump leads all the problem strip. the same colour – that might look neat but it is hard to follow. If you are buying a kit of Back to voltage and current jump leads, make sure they come in different colours. ratings: typically, you can use protoboards at voltages up one like it. Now what do you do with Another advantage of a metal baseto around 50V (total) and at it? You can start plugging components plate is that it can be connected to one currents up to around 200mA without problems. Again, higher voltages will into it to make up circuits. However, to of the power supply lines or an Earth present problems of shorts and flasho- make it more useable, the protoboard line and effectively provide a “ground vers and higher currents will inevitably needs to be mounted on a metal base- plane” for the circuit. This can be cause problems with contact resistanc- plate. Not only does the baseplate then important with audio or RF circuits provide a solid base for your circuits which may otherwise be troubled with es and maybe even local heating in the but it can have provision for power hum, instability or RF breakthrough. connector strips. And we don’t want supply connections, mounting holes In fact, you can buy protoboards on that, do we? for pots, switches and output terminals baseplates but they are quite a bit more OK, so let’s say you’ve gone out and and so on. expensive and they don’t provide for purchased the suggested protoboard or pots, switches etc. With this in mind, we have come up with a suggested baseplate design, as shown in the photos. This simply consists of a sheet of aluminium with a vertical section on one side. Viewed from the front, showing how we’ve made provision for switches, pots and various other controls. The terminals, DC input socket and switch on the right aren’t “set in concrete”: you can move these around just as you can any other component on a protoboard. SEPTEMBER 2000  71 can make your own by just getting a length of 2-pair, 4-pair, 6-pair (or more) telephone cable and cutting lengths and stripping each end as you need them. Remember, you must use phone cable with solid core wires, not multi-strand. OK, that’s enough of the background; let’s put a circuit together. Chaser circuit Fig.2: we made our baseplate from a sheet of 18-gauge aluminium cut to 270 x 200mm. The section bent up at right angles to become the control panel has holes drilled for pots, input and output sockets, terminals and so on. There is also room for a battery pack, small loudspeaker, piezo transducer or other hardware which could be glued in place. This has holes drilled in it to take the afore-mentioned pots, switches, terminals and so on. To make it, we obtained a sheet of 18-gauge aluminium measuring 300 x 300mm from Dick Smith Electronics (Cat H-2560). We cut it to 270 x 200mm, drilled a series of holes in it as shown in Fig.2 and then bent up a 70mm section at right angles to become the control panel. This baseplate is big enough to accommodate two of the Wish WB-102 protoboards side-by-side. The boards have matching lugs on their sides so that they can be locked together. Al72  Silicon Chip ternatively, there is room for a battery pack, small loudspeaker, piezo transducer or other hardware which could be glued in place. Wiring up circuits Plugging components into a proto-board is dead simple; in the case of an IC or transistor, you just line up the component leads with the holes you want and then push the component in gently. Then to make point-to-point connections on the board you need a variety of lengths of solid-core insulated wire, in a range of colours. You can buy jump wire kits but you For our very first sample circuit on a protoboard, we have chosen a simple chaser, as shown in Fig.3. This uses a 555 timer as an oscillator driving a 4017 decade counter. Five of the 4017 outputs are each used to drive a transistor and a LED. In fact, the circuit is identical to a chaser we published in the March 1994 issue. For those who did not see that issue, we will briefly describe the circuit operation. IC1, the 555 timer, is connected to oscillate at just a few Hertz by virtue of the resistors and capacitor connected to pins 2, 6 & 7. The square wave output from pin 3 of IC1 is fed to the clock input of IC2, the 4017 counter. IC2 is connected to continuously count up to five by dint of the connection of pin 1 to the reset input, pin 15. Each of the five outputs used will go high in turn and drive the base of an associated NPN transistor which turns on two LEDs in series with a 470Ω resistor. If you want a more complete circuit description you can refer to our article in the March 1994 issue which also featured a PC board. Now have a look at the photo of the assembled circuit and Fig.4 which shows the proposed wiring layout. Start by plugging in the two ICs, so that their notched ends face towards the lefthand end of the board. Then insert the resistors and capacitors. Note that the electrolytic capacitors must be correctly oriented otherwise they will have positive voltage applied to the wrong electrode and they won’t work. Next, insert the resistors and the LEDs. Note that the flats on the LEDs all face to the lefthand end of the protoboard. You can’t insert the trimpot as it is because its leads are too thick. You will need to solder some short tinned copper wires to each lead – use some pigtail lengths from a resistor. Finally, you can make all the component interconnections with the Fig.3: this chaser circuit uses a 555 timer as an oscillator driving a 4017 decade counter. Five of the 4017 outputs are each used to drive a transistor and a LED. solid-core jump leads. Don’t hurry the job because if you do, you will surely make mistakes. You will need to wire up a DC socket to suit a 6V DC plugpack to power the chaser. Alternatively, you could use a battery pack using 4 AA cells or better still, use a 6V lantern battery. A silicon diode between the supply socket and the supply line on the board protects components against accidental reversal of the power supply. This can be left permanently in place. Don’t forget to insert the two short jump leads which connect the supply lines along one side of the protoboard. Which ever way you do it, go carefully with the work and check it all carefully before applying power. When you do, you may find that some LEDs don’t light. Then it is a matter of checking your connections to the particular transistor and LEDs again and then making the correction. This is the beauty of protoboards. You can easily change the circuit – much easier than if you were assembling a PC board. OK, you’re probably itching to assemble a whole lot more circuits. Before you do, consider the circuit you have just built. Try playing around with it. Want less LEDs? Want more? Why Fig.4: you can use this wiring layout to connect up the chaser. Note that the trimpot will need thin wires soldered to its lugs before you can plug it in. SEPTEMBER 2000  73 And here’s what you see looking straight down on the protoboard. Compare this shot with Fig.4 on the previous page. As you can see, there is plenty of room on the aluminium baseplate for another protoboard (they interlock with the tabs you can see on the bottom and right), a small speaker, a battery pack or other bulky components or hardware. not try making it count to 6, 7 or 8 by connecting the reset (pin 15) to pins 1, 5 or 6 respectively (instead of pin 10). To add extra LEDs into the “chase”, simply duplicate the LED driver circuits (10kΩ resistor, BC547 transistor, 470Ω resistor and two LEDs). You might have to squash the layout a bit more but again, that’s the beauty of a breadboard. Want to make the LEDs run faster? Just reduce the value of the electrolytic capacitor connected to pin 2 of IC1. Want to make the LEDs run slower? Add another electrolytic capacitor in parallel with the one already connected to pin 2 of IC1. 74  Silicon Chip In other words, don’t be afraid to experiment as protoboards are ideal for this approach. Other observations Notice that we have used all the one colour for the jump leads on our protoboard chaser. While it looks neat, it is much harder to follow than if all the wire colours are different and that’s the way we have shown it on the wiring layout of Fig.4. You don’t have to be a genius to realise that this circuit could be wired up on the same protoboard in hundreds of different ways. No one way is necessarily better than another, although component layout can be very important in audio and RF circuits. We could also have eliminated quite a few of the jump wires by using the resistors themselves to make some of the point-to-point connections. We did it this way in an attempt to make it easier to follow. That’s all for now. We’ll present another protoboard circuit for you to SC experiment with next month. Acknowledgment: Our thanks to Dick Smith Electronics for supplying the protoboards and materials used in the preparation of this article. G E A R E D A C M O T O R S Brand new small mains operated geared motors, very strong, made for rotating microwave turntables, 240V/ 50Hz/ 3W/ 5RPM., $4Ea. or or 4 for $12. BRAND NEW GERMAN MADE MOTOR AND GEARBOX. This is a 24V motor but runs well with plenty of torque at 12V and starts at 2-3V. The output shaft is 10mm dia. and the motor is 60mm dia. X 94mm long. We believe these are made as truck windscreen wiper motors. This motor is worth well over $100, But as a special for August and Sep.2000 only... just $20 More motors on our website 20ADC motor speed controller kit (K98) $14 when purchased with the above motor. New 12V-24V inverter under development STEPPER MOTORS SANYO DENKI (Step Syn) Type 103770-6942, 4wire, main body is 67mm diam. by 51mm long, 1.5A / 4.5V, 1.8deg. steps, 0.46KG,: $15 AUTOMATIC LASER LIGHT SHOW KIT: MKIII. Changes patterns every 5 - 60 secs. Countless great displays from single to multiple flowers, collapsing circles, rotating single & multi ellipses, stars, etc. Kit inc. PCB, all on board comp-onents, three small DC motors, mirrors, precision adjustable mirror mounts & laser module. (K115) Kit with laser module $50 case $15 a special for August & September 1995. PAN / TILT DUAL SERVO CONTROLLER KIT: Ref. SC Jan 1998. This kit can be used to control two model radio control servos such as our MS1 servos. Two servos can be configured to rotate & pan a small camera (these parts are not included in kit). PCB measures 63 x 48mm and operates from 9-12V DC. The kit includes a PCB, all the on-board components, pushbutton, potentiometers, knobs, plastic case & a label: (K114) $19 RADIO CONTROL MODEL SERVO: These servos are ideal for robotics projects with good speed and high torque specifications. Servos measure 55mm long x 20mm wide x 38mm high. Used in our Robotic Arm & Servo Controller kits. Servos are supplied with a selection of output arms and disks plus mounting screws (MS1) $22 ea Ball bearing version also available. $32 ATTENTION TRAVELLERS WITH 120V MAINS (USA ETC). WE HAVE A LARGE QUANTITY OF 100-120V POWER ADAPTORS: All new quality brands (mainly Packard Bell) All with U.S. approvals 120VAC/60Hz INPUT 9VDC <at> 1A OUT 120VAC/60Hz INPUT 20VDC <at> 1.5A 120VAC/60Hz INPUT 6VDC <at> 135mA 120VAC/60Hz INPUT 18VDC <at>80mA US. IEC. MAINS LEADS 6ft long $5 ea or 5 for $20 120V/60W Edison Screw “rugged construction” type:... 10 for $10 We have commercial quantities of these items RING US FOR QUANTITY PRICES SUPER SPECIAL AUGUST / SEPTEMBER PRICES SUPER MICRO MONOCHROME CCD CAMERA MODULE: This small camera operates from 9 to 14.5V DC (1.2W) and outputs CCIR (50Hz, 625 lines interlaced) composite video (1V pp 75ohm). Horizontal resolution is 380 TV lines, CCD size is 1/3", light sensitivity is 0.2Lux. Has Auto-Iris lens. This If you mention “KTX” when ordering. camera is Infra Red responsive & can be IBM VOICE TYPE 3.0 KIT: used in total darkness This is a complete kit for with IR Illumination. Voice Dictation. Incs. available 17mm diameter x 60mm software, manual & a separately long, 20grams. Includes noise cancelling desktop 3.7mm lens: (AR717R) $99 microphone. Brand new . Software incs. VoiceType H I G H P E R F O R M A N C E IBM Anti Virus & Jungle MONOCHROME CCD CAMERA Book for Windows on CD.(IBMVT3) $22 MODULE: This small camera operates MERIT PENTIUM II MOTHERBOARD: from 7.5 to 14.5V DC (1.16W) and outputs Recent motherboard made for the latest CCIR (50Hz, 625 lines interlaced) CPU's. Std ATX form factor. Has 3 x (16- composite video (1V pp 75ohm). bit) ISA slot, 4 x (32-bit) PCI slots, 1 x AGP Horizontal resolution is 380 TV lines, CCD slot & 3 x DIMM (memory) slots, On-board element size is 1/3", light sensitivity is 1 x PS/2 keyboard, 1 x PS/2 mouse socket, 0.1Lux. Has Auto-Iris lens. This camera is 2 x USB, 1 x parallel, 2 x serial ports. With Infra Red responsive setup manual & CD, IDE & FDD cables. & can be used in total Brand new in original box. Accepts Intel darkness with IR Pentium II & Intel Celeron CPU's (NOT Illumination. 32mm SUPPLIED) from 233 to 800MHz. The x 32mm x 27mm CPU socket is SLOT-1, S-370 CPU could high & unit weighs be use with a converter board (NOT 20grams. Includes SUPPLIED). Selectable 66 & 100MHz 3.7mm lens: (AR732) $89 BUS speeds & a clock multiplier up to 8 times. Should COLOUR CCD CAMERA MODULE accept Pentium WITH AUDIO: This small camera III CPU's, on a operates from 12V DC (2W) and outputs 100MHz bus: PAL (50Hz, 625 lines interlaced) (M6TBA) $110 composite video (1V pp 75ohm). Horizontal resolution is 330 TV lines, CCD PENTIUM MOTHERBOARD: element size is 1/3", light Std. AT form factor, with VIA Apollo MVP4 sensitivity is 3Lux. Has chipset. ZIF Socket 7 for Intel Pentium (std Auto-Iris lens. & MMX) CPUs, 100 to 233Mhz, IBM / Cyrix 38mm x 38mm x 6x86/6x86L/6x86MX/M-II 150 to 400MHz, 32mm high and AMD K5/K6/K6-2/K6-III 133 to 450MHz & unit weighs 20grams. IDT Winchip C6 CPUs 200 to 225MHz. Inc. 3.7mm lens: (ARCB21) $180 Has onboard AC97 Audio & Video. 2 x DIMM sockets, 1 x (16-bit) ISA slot, 1 x HOUSED MONOCHROME CCD AMR (audio modem riser) slot & 3 x (32-bit) CAMERA: This small camera operates PCI slots. On-board IO incs. 2 x PCI IDE from 12V DC (1.16W) and outputs CCIR ports, 1 x PS/2 mouse, 1 x DIN keyboard (50Hz, 625 lines interlaced) composite connector, 4 x USB Ports, 1 x Parallel, 2 x video (1V pp 75ohm). Horizontal Serial and 1 x VGA connector. New with resolution is 380 TV lines, CCD element manual, setup CD, IDE / FDD cables & 4 size is 1/3", light sensitivity is 0.1Lux. Has back panel connectors for printer & serial Auto-Iris lens. This camera is ports, vga monitor, Infra Red responsive joystick & 3 audio and can be used in connectors In orig. total darkness anti-static bag. with IR Illumination. 22cm x 19cm: 40mm x 39mm x (EPMVP4) $90 35mm high and NEED A CPU FOR ONE OF THE ABOVE unit weighs 13g (AR830M) $99 MOTHERBOARDS... THEN CALL BRANKO FOR OUR LATEST PRICES MONOCHROME CCD VIDEO CAMERA: AND AVAILABILITY Black & white Camera is assembled on a small PCB with an auto iris lens. (IR) 3DEMON PCI TV / responsive. (0.1 lux) Can be used in total CAPTURE CARD: darkness with IR Illumination. 32 x 32 by Model PV951. With 27mm. The output is std video & can be IR remote controls. plugged into the "VIDEO IN" socket of any Brand new: Australian std VCR, video monitor or TV (PV951) $160 with A / V inputs, or via an RF Modulator to TEKRAM PCI DC-315U ULTRA SCSI an Antenna Input. The lens can be CONTROLLER CARD: This host adapter focused sharply down to a few mm(this is inc. the PCI SCSI card, manual, Driver useful for people with visual impairment). Disks and an Ultra Cable. Brand new in Spec.: Power req.: 10V to 12V <at> approx. original box: (DC315U) $50 50mA. Resolution: 400 lines approx. CCD TELEPHONY COMBO 33.6K MODEM / sensor : 1/3" (320 000 pixels). Weight: SOUND CARD: Kit inc. ISA card, manual, 30g: Version with 60° (Pin Hole) lens fitted: (CA41L60) $89 Standard Version Driver Disks, phone with 92° lens: (CA41L92) $89 Version with Cable and a Headset 120° lens: (CA41L120) $89 - Currently out with speakers and of Stock Version with 150° Microphone. Brand (Fish Eye) lens fitted: new:(MDSP2780) (CA41L150) $99 $35 (70 only) FREE FREE FREE DICTATION SOFTWARE WITH THE PURCHASE OF ANY OF THESE MOTHERBOARDS CHEAP PENTIUM UPGRADES & MORE PC FM TUNER CARD: Brand New. Allows your PC to receive FM Radio. Operates from a DOS or Windows. The software is not supplied but can be downloaded for free from http://www.packardbell.com.au/software/f mradio.zip Incs. a antenna and audio lead. Can be connected to the line input of a Sound Card or to powered PC Speakers. Setup is very easy. (RXFM) $15 KTX SP80 POWERED SPEAKERS: These are magnetically shielded, & operate from 240V AC. The amp is built in has an output of 80W (PMPO) ? with volume control and a headphone jack. Each measures 190 mm high x 75mm wide x 115mm deep. Simply connect to CD player, PC etc. viia a 3.5mm stereo plug: (SP80) $19 KTX PENTIUM II HEATSINK & FAN: Brand new in original pack with clips and a power lead terminated with a 3 pin plug. (HHSP2) $4.50 P6 HEATSINK & FAN: Designed for use with the Pentium Pro CPU. Brand new in original pack with a clip and power lead: (HHSP6T) $4.50 586 HEATSINK & FAN: This heatsink & fan is designed for use with 486 & 586 CPU's. Brand new in original pack with lead: (HHS586) $3.50 NetUPS™ 450VA UPS: Model # PRM450i. Made by Exide Electronics. AC input is 220V to 240V (selectable) <at> 50Hz via IEC socket. AC output is 230V 450VA / 280W <at> 50Hz (quasi-sine wave) via four IEC sockets. Rear panel has a DB9 comms port and two RJ45 sockets (in and out). The two RJ45 sockets provide a network transient protector, which can be used with a 10BaseT network. Included is a CD with LanSafe III and FailSafe III power management software for monitoring and shutdown capabilities for the vast majority of operating systems. With two 2m IEC extension leads, one DB9 comms cable, one DB9 to DB25 converter and manual. 370 x 120 x 165mm. Weight is 10kg: (PRM450) $250 (20 only) RARE EARTH STEPPER MOTORS WITH INCREDIBLE TORQUE SANYO DENKI (Step Syn) Type 103H7 123-1344, main body is 56X56X 54mm, 1.4A / 3V, 1.8deg. steps, 0.67KG,: $25 AS NEW LIMITED STOCKS CHECK FOR AVAILABILITY More info on the Sanyo Denki website WE HAVE A QUANTITY OF THE FOLLOWING ELECTRICAL ITEMS.... 240V EXHAUST FANS New in original box, in a stylish housing with time delay. $55 13W FLUORESCENT LIGHTS Housed in a stylish case with light defuser, tube and power switch. Ideal for mounting on mirrors etc. $20 CHECK OUT “CAMERAS” ON OUR WEB SITE www.oatleyelectronics.com Orders: Ph ( 02 ) 9584 3563 or 64, Fax 9584 3561, sales<at>oatleyelectronics.com, PO Box 89 Oatley NSW 2223 SEPTEMBER 2000  75 major cards with ph. & fax orders, Post & Pack typically $7 Prices subject to change without notice ACN 068 740 081 ABN18068 740 081 MOST OF THE PRICES IN THIS AD ARE SPECIAL PRICES FOR THE MONTH OF SEPTEMBER ONLY. PLEASE QUOTE THESE PRICES WHEN ORDERING CHECK OUT MORE GREAT COMPUTER BARGAINS ON OUR WEB-SITE SC_SEP_00 CIRCUIT NOTEBOOK Interesting circuit ideas which we have checked but not built and tested. Contributions from readers are welcome and will be paid for at standard rates. Improved engine immobiliser uses SCR This circuit was developed to improve upon conventional rev limiter or ignition killer circuits. These circuits usually employ a relay or power transistor to shunt the distributor breaker points or high voltage switching transistor. This prev­ ents the normal operation of the ignition switching device so that it cannot interrupt the coil’s primary current and thereby develop a high voltage. This was considered inefficient, as the shunting device is required to carry the full ignition coil current which can be as high as 10A peak. Other disadvantages are that any tacho­ meter reading will be disrupted when the rev limiter is operating and there is the potential to overheat the coil if the rev limiter remains in operation for too long. By contrast, this ignition killer circuit operates without carrying the full coil current. It uses a cheap SCR and does not disrupt any associated tacho circuit. It can be used in conjunc­tion with the Rev Limiter circuit published in the April 1999 issue and the Tachometer published in the April 2000 issue of SILICON CHIP. Instead of shunting the ignition coil current, the SCR shorts out the ignition coil’s back-EMF. This back EMF is pro­duced each time the points or switching transistor interrupts the coil current. The SCR is connected so that it is normally re­verse-biased by the voltage across the coil when current is flowing through it and so the SCR has no effect on normal opera­tion. SCR gate current is provided by the 330kΩ resistor connect­ed to the anode of diode D1 but normally this gate current is shunted to chassis by transistor Q1 which is normally on. If the rev limiting circuit is activated, Q1 is turned off by a low-going signal and gate current can flow to the SCR, turning it on to kill the ignition coil’s back EMF. With the gate resistor values shown, the coil’s back-EMF should be clamped to about 60V which should be insufficient for the ignition system to operate. George Mackiewicz, Vermont, Vic. ($40) Silicon Chip Binders $12.95 PLUS $ 5 P&P AUST. ONLY A really simple transistor tester Just fill in & mail the handy order form in this issue; or fax (02) 9979 6503; or ring (02) 9979 5644 & quote your credit card number. 76  Silicon Chip This circuit is about as simple as you can have for a tran­sistor tester. It feeds less than 1mA of current into the base and provided the transistor has even a modest gain, the NPN or PNP LED will light to indicate a functioning device. Power for the circuit comes from a 9V battery. David Milne, Minchinbury, NSW. ($25) Adding a timer to the NiCd discharger While the NiCd discharger published in the November 1992 issue of SILICON CHIP has been very popular, it can be made more useful by the addition of a timer. Such a timer would only run while the discharger was operating and would thereby give an indication of battery capacity. In this case the timer is a standard 1.5V crystal-con­trolled clock mechanism and it is powered by the voltage devel­oped across the discharge indicator, LED1. The existing 10µF capacitor across LED1 is increased to 100µF to enable it to supply the brief current pulses required by the mechanism. To simplify the “time” indication, only the hour hand needs to be fitted. This can be manually reset to “12” each time a battery is to be discharged and then the time is easily read at the end of the cycle. Reg Carter, Ballarat, Vic. ($25) Different colours from a green LED This circuit makes use of the fact that green LEDs tend to change colour, depending on how hard they are driven. They glow bright green when driven at currents of a few milliamps or more but at less than 1mA, the glow degenerates to an orangey-red. The effect varies with different batches of green LEDs so you will need to experiment with the resistor values. Note also that the light output at currents of less than 1mA is quite low so Truscott’s • RESELLER FOR MAJOR KIT RETAILERS • PROTOTYPING EQUIPMENT • COMPLETE CB RADIO the circuit is only suitable where the ambient light is low. David Milne, Minchinbury, NSW. ($20) WANTED! YOUR CIRCUITS AND PROJECTS! If you have a scathingly brilliant, original circuit that you’d like to share with the world – and make some money as well – send it in to us. We’ll pay up to $100 for a really good idea but there are a few conditions: • It must be your own work • It must not have been published or submitted elsewhere • It must be something other SILICON CHIP readers would find interesting. Send to: The Publisher, SILICON CHIP, PO Box 139, Collaroy, NSW 2097. email: silchip<at>siliconchip.com.au Phone: (02) 9979 5644 SUPPLY HOUSE • TV ANTENNA ON SPECIAL (DIGITAL READY) • LARGE RANGE OF ELECTRONIC COMPONENTS Professional Mail Order Service Truscott’s Amidon Stockist ELECTRONIC WORLD Pty Ltd ACN 069 935 397 Ph (03) 9723 3860 Fax (03) 9725 9443 27 The Mall, South Croydon, Vic 3136 (Melway Map 50 G7) email: truscott<at>acepia.net.au www.electronicworld.aus.as SEPTEMBER 2000  77 He has eyes! He has a heart! He has a stomach! He even has feelings! He has memory! He has a brain! He has legs! He has nerves! He’s CYBUG – The Solar Fly by Ross Tester Here’s a great “first kit” to build. It’s a simple robot which has just a few components – but is a real attention-getter! L ooking for a first kit to build, something to start you (or maybe someone else) on that path to the fascinating world of electronics? Here’s one that you’ll “fly” through. (OK, OK, I’m sorry!). But what is it? Well, you know how bright light 78  Silicon Chip attracts insects? It doesn’t just happen in nature: Cybug senses the brightest object and moves towards it. The fly’s feelers help it navigate its way around obstacles in its path – and it even has a short-term memory. Pretty clever, eh? And all this is done with just a handful of components. There are just six resistors, three capacitors, two ICs, a couple of diodes, three transistors and two motors. Oh, and two solar cells. It’s those solar cells which not only sense the bright objects, they also supply the power which drives Cybug. Cybug has a solar engine which in some ways resembles a chloroplast. In living plants, a chloroplast is the part of the plant responsible for con- verting sunlight to energy (in the form of starches). In Cybug, its “chloroplast” converts sunlight into energy, in the form of a steady voltage for powering logic (life support function) and channels any excess or bonus voltage to the motors for mobility. So in some ways, Cybug has most of the elements of a real, live animal: sight (its infrared diode detectors), nerves (transistors), a stomach (a large electrolytic capacitor to hold energy), memory (more electrolytic capacitors), brains (a voltage comparator), a heart (solar engine) and even a sense of touch (its feelers). The best part, though, is that you don’t have to feed him or water him. He gets everything he needs from sunlight. Circuit diagram Fig.1 shows the circuit of the complete Cybug Solar Fly. At its heart is the Motorola MC34164-3 micro-power undervoltage sensing circuit (Q4). (Normally we would call this an IC and label it as such but we’ll stick with the component labels as they appear on the PC board to avoid confusion later.) Q4 monitors the output voltage of the solar cells as they charge the electrolytic capacitor (C1) While ever the voltage stays high (nearly 7V), Q4’s reset stays high. Normally, if the voltage drops be- This is what you’ll get when you open the kit up: the weird-shaped PC board (left), all components, two motors and even the guitar string wire used for Cybug’s feelers. About the only extra thing you need is a roll of insulation tape. low 7V, its output is sent low but in this case, a 220kΩ resistor connected between Vin and the positive supply causes its low voltage sense to drop to 5V. This difference is called hysteresis. While the output of Q4 is high, Q3 is turned on, which will enable either of the motors to operate if either receives an input signal (via Q1 or Q2). These are Darlington transistors, which simply means two transistors connected together inside one package. They are driven by the comparator circuit, based around U1a and U1b. circus Fig.1: Cybug’s circuit. The solar batteries charge a capacitor which provides power to run the circuit as well as power to the motors. Which motor is turned on depends on the amount of light striking the infrared diodes (D1 and D2). SEPTEMBER 2000  79 These comparators monitor the voltage from each of the infrared (IR) diodes – the higher the light level, the higher the voltage. Capacitors C2 and C3 across these two diodes slow their response time, giving a little bit of “memory” to the circuit. If IR diode D1 detects more light than its partner, U1a turns Q1 on and the left motor lurches into life. The converse is also true. As the motors operate, the robot turns left and right, which could turn the “lit” IR diode away from the light. If this happens, its partner gets more light and turns the robot back in the other direction. The motor will operate while the “chloroplast” solar engine pumps out energy, keeping its capacitor charged. If there's not enough light and this capacitor discharges, the voltage sensor output goes low, removing bias from Q3 which in turn prevents either motor from operating. The end result of all this is that the Cybug moves in “steps”, according to which IR LED is receiving the most illumination. It then waits until the solar cells have recharged the capacitor before moving off again. Naturally, the more illumination the solar cells receive, the faster these steps will be. places where connections must be made and no component leads are placed. That's the case with this board – when finished, it looks like it’s missing some components but the holes are actually connection points. The technical name for one of these connecting holes, by the way, is a “via”. Note that the circuit (that is, the way the components connect together) rarely, if ever, looks just like the circuit diagram. The circuit diagram is almost always laid out neatly and clearly with a natural “flow through” of functions. The PC board tracks, which as we said form the circuit, are laid out in a way which makes everything fit but often the tracks snake their way from one side of the board to the other. Two components which are alongside each other on the circuit diagram may in fact be at opposite ends of the PC board – an vice versa! One final point before we move away from the component layout: in the vast majority of projects, we Circuits and printed circuits Now turn to the component layout, Fig.2. This shows the layout of all components on the printed circuit board (which we normally abbreviate to PC board; sometimes you will see it expressed simply as pcb). All the components mount on the top side (the side with the printing on it) with their leads poking through holes in the board to where they are soldered to the copper tracks (the “printed circuit”) underneath. These tracks connect the various components together to form the electrical circuit. Most PC boards you will use are single sided – components are on the top, the copper tracks underneath. However, the Cybug PC board is actually double-sided, which means there are also some tracks on the top side of the board immediately under the components. As you might imagine, connections must be made between the two sides. Some of these are made by the holes the components go through, with the leads ending up soldered to both the top and bottom. But there are other 80  Silicon Chip Fig.2: component layout of the doublesided pc board. No track layout is shown. publish an “X-ray” drawing of the PC board, viewed as if you are looking through it and able to see the copper tracks underneath. Of course, you cannot normally see through it but we do it this way to make component placement easier. Unfortunately, in the Cybug project, no copper pattern artwork was available, so none is shown. It is sometimes confusing to beginners when we do print both an “X-ray” image and the copper pattern itself because they are not identical – they are a “mirror image” of each other. The reason is that the PC board artwork, or pattern, is published is as if you are looking at the underside of the board from that side, while (as we said before) the component overlay is viewed from the top side – the side you put the components through. That's why they are mirror image. Building it The best approach in building a project using a PC board is to assemble the lowest-profile compo- Parts List – Cybug Solar Fly 1 Cybug PC board 2 solar cells, approx. 3.5V output 2 low voltage DC motors 1 motor bracket 2 slices of glue stick for wheels 1 double-sided adhesive foam pad 1 steel guitar string 1 100mm length brass wire 1 150mm length hookup wire 1 roll black insulation tape* Semiconductors 1 TLC27L2 dual op amp IC (IC1a, IC1b) 1 MC34164P-3 voltage detector (Q4) 3 MPSA12 high speed Darlington transistors (Q1-3) 2 Infrared LEDs (D1, D2) Capacitors 1 2200µF 16VW electrolytic capacitor (C1) 2 1µF 16VW electrolytic capacitors (C2, C3) Cybug looks like this rolled onto his back, ready for fitting the motor assembly. Two electrolytic capacitors mount on this side. nents first – almost always resistors, followed by small capacitors, then larger capacitors, and last of all semiconductors. Many components, including large capacitors (usually “electrolytic” types) and almost all semiconductors (plus some others) are “polarised” – that is, they must be connected the right way around to work. Indeed, many components will be instantly destroyed if connected back-to-front. In the case of electrolytic capacitors, there is almost always a “–” (minus) sign printed down their bodies to indicate the negative lead. The other lead is of course the positive. Always insert an electrolytic capacitor with positive to the hole marked positive and negative to the hole marked negative on the PC board. Semiconductors usually don’t have a plus or minus sign on them, mainly because most semiconductors have more than two leads (diodes being the obvious exception). Almost always, a “pinout” is shown on the circuit diagram to show you how the leads are arranged. Where transistors are concerned, they have three leads, a base, emitter and collector (abbreviated to B,E,C) and different manufacturers have used every possible combination of Resistors (0.25W, 5%) 5 100kΩ resistors (code: brown-black-yellow-gold) 1 220kΩ resistor (code: red-red-yellow-gold) * Not included in kit these positions at some stage. Always check the particular transistor against its diagram – never assume! Integrated circuits (or ICs) have from three to hundreds of legs or pins, though most of the ones you will be using as a hobbyist will have between 8 and 16. And most of those will be the “dual in-line plastic” type (abbreviated to DIP) which indeed the IC in this kit is (an 8-pin type). Have a look at the IC – you will see against one pin a little dot in the plastic. This marks pin 1 of the IC. You may also note a notch in one end – this is usually used as well as a dot but in some cases the IC will have only a dot or only a notch. With the IC held so you are looking at its top surface (ie, pins away from you) and the notch uppermost, pin 1 is always the one immediately to the left of the notch. Numbering then works anticlockwise around the IC – so pin 8 in this IC is directly opposite pin 1. One more point about semiconductors before we get into real construction. Many semis can be damaged by static electricity, so you should never handle them any more than you absolutely have to and then never hold them by their pins. This is less of a problem these days than it used to be, fortunately. OK, we’re nearly ready to start building. The first thing to do is have a good look at the PC board to make sure there are no obvious signs of damage or defects in it. In most magazine projects, a PC board pattern is published to help you do this but this is not always available (and it’s not here!). Second, check that you have all the components by checking them off against the parts list. Once again, a full list is usually published with each project. And third, ensure that you have the tools you’re going to need. Even for this simple kit, you’re going to need:  A soldering iron – the best type is a temperature-controlled model or soldering station but a mains-powered, fine-point soldering iron, intended for electronics use with about a 30W element will be OK.  Solder – a roll of electronics solder. Just because it’s in a roll doesn’t mean it’s intended for electronics use. Some plumbing solder is available in rolls or coils and this often has a corrosive flux which will eat away at the SEPTEMBER 2000  81 A close-up of the motor assembly, complete with double-sided adhesive foam (on top of the aluminium motor bracket). The motors are stuck to the motor bracket with black insulation tape. The wheels are in fact slices from hot-melt glue sticks.     PC board and eventually ruin it. Always buy your solder from electronics stores – then you know that you’re getting the right stuff! A pair of needle-nose pliers (they have very fine tips for working with small components). A pair of side-cutters (again, make sure they’re intended for electronics work. Some are sold for electricians to use but are far too big for small components!). A roll of insulation tape (preferably black). And a pair of safety glasses (to protect your eyes from bits of flying leads when you cut them, solder splashes, etc). Construction As we said before, start with the resistors. R1, R2 and R4-R6 are all the same – 100kΩ, which has a colour code of brown, black, yellow, gold. The other resistor, R3, is 220kΩ (red, red yellow, gold). Gently bend the leads of the resistors down 90°, using the needle-nose pliers, so that you have an upside-down “U” shape where the leads line up with the appropriate holes in the PC board. Check that you have the right resistors in the right holes, solder them in place (on the underside of the PC board) and snip the excess leads off with your sidecutters. We’re going to depart just a little from the order we said before: the next component to mount is Q4, the 34164P voltage monitor. This looks just like one of the tran82  Silicon Chip sistors so we’re going to identify it now and get it out of the way to save mix-ups later. This device is polarity-sensitive – it must be inserted the right way around. The flat side of the device corresponds to the flat side of the image on the PC board. Transistors or ICs with leads are seldom inserted all the way into the PC board – some lead length is left so the devices are up off the board, helping them to stay cool. Leave about 5mm of lead on the top side of the PC board and solder Q4 in on the other side. Now we will do the same with the three transistors (Q1, Q2 and Q3). Again, they have to go in the right way around and they also mount 5mm or so above the board. Next are the two infrared diodes. These are also polarity sensitive – there is a flat spot on the edge of these which marks their cathode (abbreviated K). Make sure the flat on the edge corresponds with the flat side painted on the PC board. When soldered, bend both diodes forward 90° so they emerge from the front of the PC board. And while we are at it, let’s insert and solder the two electrolytic capacitors in parallel with these diodes. There’s one big difference here – these two capacitors mount on the underside of the PC board and are soldered on top – again, watch the polarity. You can cut off the excess lead on the outside, or negative leads of these capacitors but DO NOT cut off the excess off the positive leads (the inside leads) – we are going to use them as part of the Cybug’s feelers. With your needle-nose pliers, form a small loop (about 10mm around) in the end of the lead and bend it down 90° so that it is vertical to the PC board surface. The IC is next. The notch aligns with the notch on the symbol on the PC board. When soldering the IC, be very careful because the pads on the PC board are very close together and it’s easy to bridge across them. If you need to, use a magnifying glass to carefully examine your soldering, just to make sure. We will now attach the solar cells to the PC board. These require short (10mm) lengths of hookup wire. In the kit, this was supplied as a length of multi-part wire (actually computer connection cable) but fortunately this is easy to separate into individual lengths. Cut four lengths and strip the insulation of, say, 3mm each end. Carefully solder these four lengths to the solar cells + and – terminals. Place the solar cells on the PC board and solder the other end of the four wires into the holes marked S+ and S–, with the pluses and minuses corresponding with the same markings on the solar cells. The cells are held in position with insulation tape across their undersides, sticking them to the underside of the PC board. You only need short lengths of tape to do this. Tools for hobby electronics: on the left is a pair of side-cutters and a pair of needle-nose pliers, on the right a mains-powered soldering iron on a stand. The motors are wired to the PC board in a similar way, except that this time we are going to need 8cm lengths. On each motor, note which terminal has a red dot – this is the positive terminal of the motor and it is connected to the “MOTOR” pad on the PC board marked with a +. Before that, though, use some more of your black electrical tape to secure the motors to the support bracket. (DC motors are only polarised in the sense that connecting them back-to-front will cause them to run backwards). Also, when soldering in the wires from the motors to the PC board, they need to cross over – the right motor connects to the M1 pads which are on the left side of the board and the left motor to the M2 pads on the right side of the board. The wheels are actually slices of hot-melt glue sticks and we fix these to the motor shafts by melting the centres of the “discs” with the soldering iron, sliding them onto the shafts and holding them squarely in place until the glue hardens again. Nifty, eh? (Not only that, but if you “throw a wheel”, you’ll know how to make another one and mount it!) The motor mounting bracket, with motors and wheels, mounts to the PC board with double-sided adhesive foam (supplied). The assembly needs to be attached as close as possible to the centre of gravity of the PC board for best performance. The final component, as such, to mount is the large electrolytic capacitor (C1) which is in parallel with the solar cells. Again, this capacitor is polarity sensitive. It can be mounted either standing up, in the normal way, or lying flat down on the board as a sort of “tail”. It’s up to you. The feeler wires In the kit is a length of steel guitar string wire. This must be cut to form the feelers but we have to warn you, it is very tough – probably tougher than the jaws of your sidecutters and may “nick” them. So you might prefer to find an old pair of cutters or even some old scissors to cut the wire. Don’t be tempted to pinch mum’s good scissors to cut it – you may find Cybug suddenly becomes very flat and you won’t be able to sit down for a week… Cut two lengths of guitar string wire 120mm long and bend down 90° 5mm from one end. Thread an end through the left feeler loop, bend first, and solder it to the pad beside the “C2” marking on the PC board. Repeat for the right feeler, soldering it into the pad by the “C3” marking. Once in place, grip the feelers about 50mm from the PC board and bend outwards 90°. You may also want to bend them down a little so they’re close to (but not touching) the ground, and thus able to detect small objects low down. Now carefully adjust the feelers so they lie, at rest, in the middle of the loops you made earlier. (It may be easier to adjust the loops in some cases). The idea is that when a feeler touches something, it is pushed onto the loop, making contact with it. The rest of the time, no contact is made. Last, cut the two antennas – these are about 70mm long with the same 90° bend 5mm from one end. These are soldered into the empty holes on the right and left sides of the head. The antennas are normally just for decoration but can form part of an optional power pickup (see panel). Finally, install the two stabilisers which prevent the robot from tipping forward or backward. These are made from two 80mm lengths of the heavier brass wire. One is soldered into either of the two small pads at the very end of the Cybug while the other goes to the larger hole Where do you get it? Cybug is distributed exclusively in Australia and New Zealand by Dick Smith Electronics and is available at all stores or through DSE Mail Orders or via their website, www.dse.com.au The complete kit sells in Australia for $71.31 including GST Here’s what your finished Cybug should look like with his motors and wheels attached, his feelers, wheels and front/rear stabilisers. right in middle of the head. Bend the ends of the brass wires into a “J” shape so the wires won’t jag on anything. If you wish, a ground wiper wire can be made from a 50mm length of guitar string wire, soldered into the small pad just above the IC. This will be used if you create a “feeding station” for your Cybug. That completes the assembly. If all is well, it should look much like the photographs. All that remains is to check it out. With the sun high overhead (so as not to act as a distraction to the infrared diodes), hold small white objects in front of Cybug and watch as he lurches towards them. If he goes the wrong way, you either have the motors connected back to front (remember we said they had to cross over) or wired in the wrong polarity. What to do next Try increasing the size of C1 – larger sizes will produce longer delays between each step but the steps themselves will be much larger. If you use a much larger capacitor (many thousands of microfarads) the robot will take a few seconds to charge in direct sunlight but will move for two to three seconds per step. The instruction book which comes with the Cybug kit will also give you some other ideas to try, including a “feeding station” where he picks up extra power from a 9V battery. You could also pick up even more tips by visiting Cybug's website, http://members.home.net/cybug SC SEPTEMBER 2000  83 VINTAGE RADIO By RODNEY CHAMPNESS, VK3UG HMV’s Nippergram: a classic 1950s portable radiogram Portable radiograms became popular during the 1950s and early 1960s and are now very much collector’s items. One classic from that era was HMV’s Nippergram. By the early 1950s, 78 rpm records had become well established and listening to music was a popular pastime. The subsequent release of 33 rpm and 45 rpm micro­groove longplay records continued this trend. These were a quan­tum leap ahead of the older 78 rpm records – they had less surface noise, were lighter and less fragile, and it was possible to play upwards of 20 minutes per side. However, you had to keep them out of the heat or they buckled. With multi-stack record changers, several hours of continu­ous playing was achievable. The lounge room radiogram became an elegant piece of furniture in many homes, having taken over from the console radio of the 20s, 30s and 40s. In earlier times, it was quite practical to take a wind-up gramophone out into the backyard to play music but lugging a lounge room radiogram outside was an entirely different matter. The answer to this problem lay in the development of a portable record player which could easily be taken outdoors and attached to power via an extension lead. At the same time, many young people were starting to live in flats and other dwelling places with limited space so a miniature radiogram made a lot of sense. Being small, its audio output and fidelity would not be anything to write home about but at least people could have their radio and play their records too. Several manufacturers, including Kriesler, Astor, HMV and others, rose to the occasion and produced their own versions of the compact radiogram. One of the most famous was the HMV Nipper­gram. The HMV Nippergram This is the view inside the cabinet of the old Nippergram prior to restoration (note the buckled turntable platter). A previous serviceman had installed the turntable the wrong way around. 84  Silicon Chip HMV produced many fine and interesting pieces of radio equipment over the years and the Nippergram in its various models is one of them. As can be seen in the photographs, the unit isn’t exactly small but it can be carried reasonably easily over short distances. Unfortunately, when it came to servicing, the radio section in the unit I was restoring wasn’t all that easy to remove from the cabinet. First, the record changer had to be removed because a couple of screws that secure the radio in place were too close to the changer for a screwdriver to be used. However, in my unit, the changer had to come out and be overhauled anyway. To remove the changer, all the wood screws around the mounting platform were removed and then the changer was eased up by lifting it at the edges. It’s a bit of a tight fit and takes some time to do. Once the changer was lifted clear, the screws holding the radio in place could be accessed. These screws (a total of four) were removed and the two screws on the outside of the cabinet around the speaker grille (these release the speaker clamps) were loosened, after which the set was gently lifted out. My next task was to remove the cables connecting the record changer to the radio chassis and unscrew the aerial/earth termi­nal block at the back of the cabinet. With all of these things undone, all of the innards were lifted clear of the cabinet. Now all sections could be worked on. But would you believe it? – the last person to work on the unit had put the changer in the wrong way. Had he installed it cor­rectly, access to the receiver would have been quite straightfor­ward. Did someone say something about Murphy’s Law? It seemed appropriate to commence restoration with a good clean-up; ie, cleaning the cabinet inside and out, the record changer and the set itself. The cabinet was cleaned with warm soapy water and a small scrubbing brush, then left to dry in the sun. The leatherette finish responds quite well to this. When it was dry, vinyl restorer was sprayed on and rubbed into the leatherette. This took the tired look away and the cabinet is now almost like new – if you ignore the marks that cannot be removed, such as burn and scuff marks. By the way, items treated with vinyl restorer look nice but can be rather slippery. A friend used this product on a bakelite cabinet and it looked tremendous. However, as he was moving it, it slipped from his hands and the cabinet did not bounce at all well! The record changer was cleaned using a tooth brush and soapy water. This cleans all the gunk off quite well but you have to proceed carefully, so that no water gets near the pickup car­tridge or the works underneath. The receiver was so well protected from the elements that the chassis looked as though it had just come out of the factory. The knobs were the only things needing a clean and they The rubber mounts for the motor had perished and had to be replaced. The mounting position is indicated by the white arrow at bottom right, while the second arrow indicates the motor itself after removal. In this photo, the motor has been bolted back into position, following the replacement of its rubber mounts. A fair amount of time was spent cleaning the underside of the turntable and oiling the moving parts. too were scrubbed with a toothbrush and soapy water. Restoring the radio The Nippergram is a 5-valve unit using a 6BE6 as a convert­er for both broadcast and shortwave (6-18MHz), a 6BA6 455kHz IF stage, a 6AV6 as the detector and first audio stage, a 6M5 audio output stage and a 6X4 rectifier. I couldn’t find the exact circuit for the Nippergram but it appears similar to SEPTEMBER 2000  85 Fig.1: the HMV Nippergram uses voice-coil negative feedback in the audio output stage. An incorrect connection resulted in positive feedback and a howling noise from the loudspeaker. the E43G (some circuits didn’t manage to get published in the AORSM manu­ als) and would appear to be circa 1952/5. All the usual problems with circuit components reared their ugly heads. Anyone restoring an old set like this can be sure that there will be several leaky paper capacitors and this set was no exception. In fact, even before I turn a set on I re­ligiously replace all the critical capacitors – the audio coupler between the 6AV6 and 6M5, the AGC/AVC bypasses and usually the HT RF bypass. I also checked the resistors and found a few out of tolerance which I replaced. By the way, it is often necessary to lift an end of a resistor out of the circuit for checking, as any parallel bits will affect the reading. Next, the speaker transformer was checked and in this case it had an open circuit primary winding and so This view shows the top side of the changer with the turntable removed. A stepped pulley on the motor is used to set the turntable speed, via a stepping mechanism attached to the record speed control. 86  Silicon Chip it was replaced. I seem to be having a run of these lately. Having done all of these things, including checking for shorts between the HT rail and chassis, I turned the set on for the first time. In order to observe what was happening, I had connected a multimeter (set to the 400V range) between the HT line and chassis. As it warmed up I was greeted by a violent howl from the speaker. Well at least the audio output was working! What was causing the howling? This set, like many others, uses voice coil negative feedback. This is accomplished by con­ necting the cathode bypass electrolytic capacitor (C22) to the unearthed end of the voice coil, as shown in Fig.1. The transformer that had been in the set and the nondescript replacement I used were not colour coded in the same way, so I had only a 50% chance of getting the feedback right. I got it wrong and so had positive instead of negative feedback, hence the howl. Overcoming this problem was easy – just swap the two voice coil wires out of the transformer, so that the one that was earthed became the unearthed lead and vice-versa. Now that music was coming from the loudspeaker, I knew that there weren’t too many other problems to be found. However, as a precaution, I replaced most of the other paper capacitors, leav­ing only a couple in positions where leakage would be of no concern. For example, the IF stage valve cathode has a 220Ω resistor from cathode to chassis, so the capacitor across it would have had to be very leaky to cause problems – hence it was left in. At this stage, I decided to check the IF alignment but soon ran into trouble. The output was up and down like a yo-yo if I moved or touched anything. I eventually traced the problem to the wave-change switch. A hefty dose of contact cleaner fluid and operating the control quite a few times cleared the problem. Next, I attached a signal generator with modulated output to the grid of the 6BE6 and tuned it to around 455kHz to get a response from the set. I found that the IF was near enough to 455kHz so all I had to do was find out if the cores were where they should be. The output was reduced so that the output from the receiver was just above the level at which it became noisy. I tweaked each core with an insulated adjusting tool and found that peak performance was achieved if they were left where they had been. By the way, a plastic knitting needle with the end filed flat like a screwdriver blade is ideal as an insulated alignment tool. If a metal screwdriver is used, the metal upsets the tuning and it is extremely difficult to tune the IF coils cor­rectly. The dial mechanism was in good order, needing only a drop of oil on each of the pulleys. This mechanism needs to be in good order before any serious attempt is made to align the front end of a set. The dial lamps were all working too, which made a welcome change. The next job was the broadcast band alignment. The stations were found to be where they should be so the oscillator was spot on and only a minor tweak to the aerial trimmer around 1400kHz was needed to get the best performance. In fact, the alignment of this band was very good considering the set’s age. The shortwave band alignment was quite a different story, with the oscillator about 1MHz out at 17MHz. This was corrected and the aerial trimmer adjusted as well. However, at the 6MHz end, it was still out by some way and there is no adjustment. Oh well, who seriously listens to shortwave on these sets anyway? After all, the frequency calibrations are far from pre­cise at the best of times. In another article, I’ll go into alignment in much more detail and discuss how to correct align­ment problems. In any case, the receiver is now working well and no valves needed replacement. Remember when people used to say “its only a valve” when they took their valve radio in for repair? The record changer In my opinion, the many later variants of the BSR record changer are simple, relatively trouble-free and usually easy to set up so that they work properly. As you can see from one of the photographs, there isn’t a great deal underneath the frame. Record changers are almost entirely mechanical devices. There’s only a small amount electronic circuitry (if one could call it that) to transform The HMV Nippergram, fully restored and ready to go. Note the position of the stabiliser arm now that the turntable has been installed correctly. the information in the grooves on the record to an electrical signal for an audio amplifier to work with. So how do you get one of these devices up and running? This can take some time if years of dust has impregnated itself into the congealed grease. The first job is to clean all the gunk off the mechanism using a rag and some cotton buds moistened with household kerosene. I usually start on the top side. The turntable was removed by first removing the circlip at the centre of the turntable, then gently pulling it up while turning it clockwise. This exposed the works under the turntable; not that there is a lot to see here. Next, the rubber idler pulley was removed and emery paper used to roughen up the edge. Sometimes the rubber on the idler becomes hard which may mean restoration is difficult or impossi­ble as I’m not aware of a source of supply. One problem I found was that the idler was not contacting the stepped drive pulley correctly. It didn’t take long to find out why – the rubber resilient mounts on the motor had perished and the motor assembly was sagging and pulling the pulley out of position. The mounts look rather like rubber grommets but the centre hole is much smaller. I wondered for a while what could be used in their place before remembering that I had bought some tuning-gang rubber mounts (grommets) some time ago. They turned out to be almost perfect and only needed a small plastic sleeve to fill the gap SEPTEMBER 2000  87 When it’s all folded up, the HMV Nippergram looks very much like a luggage case. This photo shows the unit before it was given the vinyl restorer treatment, which made the case look like new again. between the motor mount spigot and the inside edge of the grommet. A photograph shows the motor removed so that this could be done. While the motor was out, the bearings were oiled. With some units, it’s possible to oil them through a small hole in the side of the bearing case. The bearings are phosphor bronze and usually have a felt pad around them to contain the oil. I undid the screws holding the bearing in the motor and this gave sufficient access for oiling. There were covers over the bearing assembly but it was possible to flood the bearings and the felt pads through gaps in the assembly. The idler pulley bearing was also oiled and the motor was then reassembled and fitted back in place. The stepped pulley on the motor is used to set the turntable speed, via a stepping mechanism attached to the record speed control. This was greased and oiled after being cleaned. However, the idler pulley still wasn’t sitting in the middle of each section of the pulley as selected by the speed control. This problem was solved by undoing the grub screws on the motor shaft and shifting the pulley enough so that the idler contacted the middle of each section. The pulley and speed control system were now working well, or so I thought. The underside of the record changer is a bit more complex and it is harder to see what is really going on. First, the 88  Silicon Chip congealed grease, gunk and fluff on all the gears and slides and shafts was removed. Some areas are not easy to get at but by using a kerosene-soaked rag and cotton buds, most of the muck can be cleaned off. Having done that, sewing machine oil was used to lubricate the mechanism and the slides, as appropriate. The changer was then mounted on a “servicing board” (to be described next month) so that its operation could be observed. Before applying power, the pickup The two arrows in this underside view of the tonearm point to the stylus weight adjust­ment spring (top) and to the drop-in point adjustment screw. cartridge was turned midway between the microgroove and 78rpm positions, so that the stylus was no longer exposed. The stabiliser arm was then pulled up and moved to the side (as when records are going to be loaded) and the changer operated in automatic mode at 78rpm. If the system is sufficiently clear of gunk, the tone arm will come down part way across the platter, then move towards the centre and lift off. It should then go through this routine ad infinitum, so that the oil and grease gradually works its way into all moving and sliding parts. My unit worked OK at 78 rpm, so then it was time to see if it operated correctly at 45 rpm, 33 rpm and 16 rpm. Unfortunately, it didn’t – at least not initially – and the arm wouldn’t position itself correctly to drop onto the selected record size. Obviously the oil hadn’t penetrated into all the necessary spots and I also found that I hadn’t oiled one shaft! A few drops of oil soon loosened things up and the arm dropped into the correct position each time it went through its cycle. However, the only way I could stop the unit from stalling during record changing was to shorten the spring on the idler pulley, to apply more pressure on the idler/motor pulley surfac­es. Adjustments Having got the mechanism working properly, it was time to adjust the drop-in position of the pickup stylus onto the run-in groove on the discs. This is done by adjusting a screw under the tonearm, as indicated by the white pointer in the photograph. The stylus weight should be around 3-4 grams. This is hard to measure but a good approximation is achieved by adjusting the position of the spring in the holes, this time indicated by a yellow pointer. It should be adjusted so that the pressure is the lowest that will allow the stylus to track properly and not skip on the run out groove. At this stage, I’m still chasing some rubber to replace the perished platter. The pick-up head works fine so my vinyl records can expect to get a go on the Nippergram. It is a good idea to change the stylus if you intend to play records and many different styles are available from WES Components SC in Ashfield NSW. ASK SILICON CHIP Got a technical problem? Can’t understand a piece of jargon or some technical principle? Drop us a line and we’ll answer your question. Write to: Ask Silicon Chip, PO Box 139, Collaroy Beach, NSW 2097. Design fault in constant voltage charger I refer to page 71 of the July 2000 issue of the magazine, describing a constant voltage charger using an LM317 regulator. In the data sheet for the LM317, under the heading of Abso­lute Maximum Ratings, it specifies the input-output voltage differential as +40V, -0.3V. This means that you cannot reverse bias the input/out pins by more than 0.3V. In fact when an input filter capacitor is used, they recommend a reverse-biased diode across the regulator to prevent this happening. In the charger circuit published, the input voltage to the regulator goes to zero every half cycle but the output remains at battery voltage, thus reverse biasing the regulator. I am not sure that the regulator will last too long in this configuration. I doubt if a lot of the circuits attached to data sheets have actually been tried and National Semiconductor engineers make mistakes just like the rest of us. No doubt in the fine print somewhere, it will say that it is up to the user to see that absolute Using a Peltier device to cool a CPU Could the Peltier device you used in the Esky cooler (Sep­tember 1999) be used for cooling a CPU? How about doing an article on building a Peltier cooler for around $65 or there­abouts? With the new Celeron CPU overclocking to 800MHz+, this would be great. I would like to get the CPU temperature down to 20°C or better. (T. A., via email). • While there is nothing wrong with the concept of using a Peltier device to cool a CPU (we looked at the idea at the time we did the Esky), the idea has several “logist­ ical” problems. maximum ratings are not exceeded. Please put my name forward for “Nit-picker of the month” award. Free trip to Silicon Valley? (R. W., Nathan, Qld). • In this circuit the input/output pins can never be reverse-biased because the input is fed by a bridge rectifier – no re­verse current can flow. And in the case of an LM317, there is no equivalent problem with the output/ adj pins either. Sorry we can’t send you on a free trip to Silicon Valley but you do get brownie points for trying. Upgrading the Discolight I have just purchased a kit of the Discolight described in the July & August 1987 issues. I am wondering how to upgrade the output stages so that they will handle 5A loads in each channel. I need to do this because I have a number of 600W spotlights I want to control with it. I am also wondering if I can use the prewound ferrite chokes from Jaycar (Cat LF-1270) in the EMI suppression networks so that I don’t have to wind the chokes. (J. P., Toowoomba, Qld). First, the PC manufacturers/chip suppliers told us that you would certainly void the warranty (from both) if you didn’t use the specified fan/heatsink – regardless of whether a Peltier device would do the job better or not. Second, the mechanical aspect could be a problem – clamping the Peltier to the CPU. Finally, the matter of cost rears its head. You already get a fan/heatsink with the CPU which would be redundant and then you’d have to spend (as you say) at least $60 or so to replace it. It didn’t seem like the idea had any mileage at the time – indeed, yours is the first request we’ve had for doing it. • The maximum individual incandescent lamp rating we would recommend for the Discolight is 150W. If you use larger lamps, the chances are that the specified 8A Triacs will blow if one of the lamp filaments blows. The reason for this is that when the filament in a large lamp blows, the loose filament ends tend to flail around and establish an arc between the main filament stem supports. This arc current can be very high, as much as 100A or more – until the stem fuse in the lamp blows. However, before the stem fuses blows, the arc current will blow the Triac. Commercial lighting desks avoid this problem with big spo­tlights by using 40A Triacs. And that’s what we did in the 4-channel lighting desk described in the June & July 1991 issues. So we suggest that you modify the output stages of the Discolight so that they are the same as in our 4-channel lighting desk. The output configuration is identical apart from the bigger insulat­ed-tab Triacs, bigger capacitors in the suppression networks and heavier wire in the toroidal chokes. You cannot use the Jaycar prewound chokes in the Discolight because they have ferrite cores instead of the powdered iron cores we have specified. We have specified powdered iron cores because they are an integral part of the EMI suppression net­works. The powdered iron cores have a lower Q than ferrite cores and tend to “damp out” any oscillations in the filter network. Note that we have used the same size Neosid cores in the 4-channel lighting desk as we did in the Disco­ light. However, the lighting desk toroidal chokes used heavier gauge wire and a smaller number of turns. Tacho reads three times reality I have just completed assembling a digital tacho kit as de­scribed in the April 2000 issue. I have been able to program it for a 6-cylinder Torana XU1 with a points distributor but it seems SEPTEMBER 2000  89 Building a monster float charger I am thinking about building your 12V float battery charger as published in your October 1998 issue but I would like to make a few modifications to it. The first question regards the trans­ former I plan to use. It has both 12V and 24V taps and is rated at a whopping 16A! I would really like to use this particular transformer (for reasons I shall describe latter) but I feel that because it is only 12V and your kit uses 15V, there may be some adjustments needed. The transformer measures 13V unloaded but I imagine this will drop when it is loaded. I thought that maybe the feed resistors to the base of Q1 might need to be changed as they monitor the voltage across the battery. It is stated that the circuit drops back to trickle charge when the battery reaches 14V but if the transformer can only reach a maximum of 13V, it would seem that the circuit will continue to charge flat out. Could you please advise me as to what changes need to be made if this transformer can be used? The second question is regarding to be reading about three times the engine speed. At idle, it reads about 3000 RPM when it should be reading around 800-900 RPM. I checked the calibration as per the instructions. I fed 200Hz (my oscillator would only go down to 200Hz) into the low input, set it for 4-cylinder operation and read 6000 RPM which is OK. In 6-cylinder mode, I measured at pin 2 of IC2a with a Fluke meter which reads frequency. The reading was about 40Hz at idle and IC1 pin 6 read about 120Hz. I set the engine revs at 3000 RPM and measured about 500Hz at pin 6 of IC1. Have you any idea as to what may be wrong? (G. H., via email) • The incorrect reading when connected to your vehicle is almost certainly due to false triggering caused by points bounce. Try shunting the .056µF capacitor at the input with a larger value, say 0.1µF to 0.22µF. 90  Silicon Chip Q4 in the circuit. It is a 2N3055 transistor rated at 15A. Because I would like to use the circuit to quickly charge heavy-duty truck type batteries, it would be good if I can use the full 16A that the transformer can deliver at the start of the charging period. What value and wattage resistor I should use for “Rs” and what other components need to be changed due to the current limit of 16A? Secondly, can I replace Q4 with a more powerful substitute like an MJ15003 or a TIP35C? (T. B., via email). • Our guess it that with such a generously rated transformer you would not need to change the circuit at all. The circuit will shut down the current as the battery voltage rises because that it what it is designed to do. However, if you want to charge at 16A that is altogether a different proposition because Q4 can only dissipate about 10-15W with the specified heatsink and current limit figure of 2A. If you wanted 16A you would need a very large heatsink and prob­ably at least six transistors in parallel and each with emitter resistors to ensure current sharing. It is really not practical to extend this circuit in this way. Suspect PIC in digital tachometer I’ve completed the kit for the digital tachometer from the April 2000 issue and am having some problems. When trying to calibrate, I get the expected “000” and the first seven LEDs in the bargraph. However, when I press the mode switch, nothing happens. Is this a sign that the PIC chip (PIC16F84P) is blown or is it a problem somewhere else? I did have some problems initially when I first tested it (ie, a short on the PC board) but have since replaced most components and tested the other ones. The only other problem I could see is if I had the switch the wrong way round but I checked it both ways and had no re­sponse either time. If the PIC has had it, how can I acquire a new one that is pre-programmed without having to buy a whole new kit? (A. K., via email). • It is unlikely that the PIC is damaged. Check that pin 3 of IC1 is normally held high when the switches are off. You can do this by measuring the voltage between ground and pin 3 and it should read 5V. If this is not the case, then there is either a short to ground at pin 3 or along the PC tracks leading to the switches. Alternatively, one of the switches (Mode, Up or Down) could be oriented incorrectly. Try pulling out all the switches first and recheck that the pin 3 voltage is now at 5V. The switches should be inserted with the short circuit connection between the top two pins and also across the lower two pins. The connection between the top and lower pins of the switch should be a short only when the switch is pressed. Boosting the 500W amplifier I have a question about the 500W amplifier published in the August to October 1997 issues. I have a pair of 65V 1kVA toroidal transformers. I got them at a very special price. What would happen if I used these instead of the 57V 800VA toroidal recommended for the project? What modifications would I need to make to the components to accommodate the extra rail voltages? I note that the amplifier is basically an uprated version of the 175W amplifier of April 1996. This would seem to suggest that there is room for slight modifications to cope with the extra voltage. (P. O., via email). • Sorry but 65V is just too high. You would be increasing the overall amplifier dissipation by more than 30% and there is no way the design could cope with it. Using the compressor for harp recordings The CD compressor in the June 2000 magazine looks like a good one, with specifications equal to or better than many com­mercial units, and a lot less expense involved. I was considering building it into a rack panel, with inbuilt power supply and using it as a compressor/peak limiter in a PA system and for a recording studio. I play the harp and recording it is quite difficult. The initial pluck of the string is a very short loud transient followed by a gradual delay which plays havoc with recording and signal processing systems. The idea is to limit this initial transient and have mini­mal effect on the rest of the signal. Most commercial compressor/limiters have extra controls such as independent attack and delay. This would seem to be easy to do by just in­stalling potentiometers on the front panel wired up to the at­tack/ delay circuit, presumably in place of R1 and R2. However, commercial units also have a threshold control which is adjusted so that up to a predetermined level, no com­pression occurs. It would seem possible to install this feature in the CD Compressor. Could VR6 be the correct control to use? Also I would like to install a “compression meter” as used in upmarket compressors. It is simply a meter connected to the VCA control input so that one can see how much compression is being applied at any one moment. Would pin 11 of IC2 be the right place, buffered via an op amp and rectifier, etc. The reason for this is so that the input level can be adjusted for the desired amount of limiting. I have asked quite a lot so here’s hoping you can help. (R. H., Mullum­ bimby, NSW). • The attack and decay resistors R1 & R2 could be changed for potentiometers wired as variable resistors to allow adjustment of these parameters. The threshold control VR6 is actually there to operate the downward expander and is not suitable as it stands for use as a threshold control whereby there is no compression until the threshold level is reached. However, you could forego the downward expansion facility and change the 2.2kΩ resistor at the output of diode D5 to a value that does not set downward expansion; eg, 22kΩ. Then Notes & Errata PC-Controlled VHF FM Receiver, June 2000: the LM385Z isometric drawing on the circuit diagram shows the “ADJ” and “-” pins reversed. 40V/1A Adjustable Power Supply, June/ July 2000: the LM336Z isometric drawing on the circuit diagram in the June issue shows the “ADJ” and “-” pins reversed. The correct pinout drawing for both the LM336Z and LM385Z is shown above. Loudspeaker Protector & Fan Controller, August 2000: the base resistor for Q8 on the wiring diagram (page 59) is incorrectly shown as 2kΩ. It should be 1.5kΩ, as shown VR6 control can be used to adjust for compression threshold. A compression meter could be added to the pin 11 control for IC1 and IC2, as you suggest. Vehicle loop detector wanted I am looking for a loop detector circuit, similar to those found at traffic intersections, to use in the control of an electric gate. I have built up a simple (inductive) metal detec­tor circuit from a recent issue of SILICON CHIP but I’m guessing it will need far more gain and probably a very large pickup loop for it to detect the presence of a vehicle reliably. I may yet have to build up a large diameter loop and try it but thought I would ask you the question first. Do you know of, or have come across some sort of metal detection circuit on the circuit diagram (page 55). Also, the connections to LED1 and TH2 were incorrect. The connections should be as shown in the diagram above. that could be used in this application? I realise I could take the easy way out and simply use something optical but this then may also be triggered by objects other than cars. I have found lots of interesting websites with commercially available detectors advertised but, of course, they want an arm and a leg for them and they provide no circuit details. Any thoughts or suggestions? (P. W., via email). • We have not published a large loop detector circuit. The recent metal locator may well form the basis of a viable circuit and while you will have to increase the area of the loop to, say, 0.5m2, it may not be necessary to increase the sen­sitivity; after all, you are going to detect a rather large lump of metal. In fact, we have seen a traffic light loop being tested and they used a 60cm length of steel which they SC dragged over the road surface. WARNING! SILICON CHIP magazine regularly describes projects which employ a mains power supply or produce high voltage. All such projects should be considered dangerous or even lethal if not used safely. Readers are warned that high voltage wiring should be carried out according to the instructions in the articles. When working on these projects use extreme care to ensure that you do not accidentally come into contact with mains AC voltages or high voltage DC. If you are not confident about working with projects employing mains voltages or other high voltages, you are advised not to attempt work on them. Silicon Chip Publications Pty Ltd disclaims any liability for damages should anyone be killed or injured while working on a project or circuit described in any issue of SILICON CHIP magazine. Devices or circuits described in SILICON CHIP may be covered by patents. SILICON CHIP disclaims any liability for the infringement of such patents by the manufacturing or selling of any such equipment. SILICON CHIP also disclaims any liability for projects which are used in such a way as to infringe relevant government regulations and by-laws. Advertisers are warned that they are responsible for the content of all advertisements and that they must conform to the Trade Practices Act 1974 or as subsequently amended and to any governmental regulations which are applicable. SEPTEMBER 2000  91 REFERENCE GREAT BOOKS FOR NEW NEW NEW NEW AUDIO POWER AMP DESIGN HANDBOOK INDUSTRIAL BRUSHLESS SERVOMOTORS From one of the world’s most respected audio authorities. The new 2nd edition is even more comprehensive, includes sections on load-invariant power amps, distortion residuals, diagnosis of amplifier problems, and much more. 368 pages in paperback. Designed as a guide for professionals and a module text for electrical and mechanical engineering students. A step-by-step approach covering construction, how they work, how the motor behaves and how it is rated and selected. It may only be a small book but it has outstanding content! 186 pages in hardback. By Douglas Self. 2nd Edition Published 2000 By Peter Moreton. Publ. 2000 85 $ VIDEO SCRAMBLING AND DESCRAMBLING for Satellite & Cable TV by Graf & Sheets SETTING UP A WEB SERVER If you've ever wondered how they scramble video on cable and satellite TV, this book tells you! Encoding/decoding systems (analog and digital systems), encryption, even schematics and details of several encoder and decoder circuits for experimentation. Intended for both the hobbyist and the professional. 290 pages in paperback. NEW 2nd By Simon Collin. Published 1997. 65 $ Edition 1998 TCP/IP EXPLAINED Covers all major platforms, software, links and web techniques. It details each step required to choose, install and configure the hardware and software elements, create an effective site and promote it successfully. 273 pages, in paperback. 99 Assumes no prior knowledge of TCP/IP, only a basic understanding of LAN access protocols, explaining all the elements and alternatives. Combines study questions with reference material. Examples of network designs and implementations are given. 518 pages, in paperback. THE CIRCUIT DESIGNER’S COMPANION $ Includes grounding, printed circuit design and   layout, the characteristics of practical active and    passive components, cables, linear ICs, logic   circuits and their interfaces, power supplies, electromagnetic compatibility, safety and     thermal management.     302 pages, in    paperback. 65 LOCAL AREA NETWORKS: An Introduction to the Technology ELECTRIC MOTORS AND DRIVES Want to become more familiar with local area networks (LANs) without facing the challenge of a 400-page text? . Gives familiarity with the concepts involved and provides a start for reading more detailed texts. 191 pages, in paperback. For non-specialist users – explores most of the widely-used modern types of motor and drive, including conventional and brushless DC, induction, stepping, synchronous and reluctance motors. 339 pages, in paperback. By Austin Hughes. 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Third edition published 1997 by Butterworth-Heinemann. $ 59 A very useful text for anyone wanting to become familiar with the basics of telephone technology. The 10 chapters explore telephone fundamentals, speech signal processing, telephone line interfacing, tone and pulse generation, ringers, digital transmission techniques (modems & fax machines) and much more. Ideal for students. 367 pages, in soft cover. AUDIO ELECTRONICS $ 88 By Lilian Hobbs. First published 1996. Second edition 1999. 85 $ All you need to get started. Create and design your own Internet home pages that include both text and graphics, using this practical, easy to follow, jargon free guide. This edition has been enhanced and updated and now covers HTML 4.0. 182 pages, in paperback. DIGITAL ELECTRONICS – A PRACTICAL APPROACH GUIDE TO TV & VIDEO TECHNOLOGY 59 Eugene Trundle has written for many years in Television magazine and his latest book is right up to date on TV and video technology. The book includes both theory and practical servicing information and is ideal for both students and technicians. 382 pages, in paperback. EMC FOR PRODUCT DESIGNERS By Tim Williams. First pub­­ lished 1992. Second edition 1996. Widely regarded as the standard text on EMC, this book provides all the information necessary to meet the requirements of the EMC Directive. It includes chapters on standards, measurement techniques and design principles, including layout and grounding, digital and analog circuit design, filtering and shielding and interference sources. The four appendices give a design checklist and include useful tables, data and formulae. 299 pages, in soft cover. P&P AUST: Add $A5.50 per book – Orders over $100 P&P free in Australia. NZ: Add $A10 per book, $A15 elsewhere 27 $ By Richard Monk. Published 1998. By Eugene Trundle. First pub­­lished 1988. Second edition 1996. $ 00 This practical handbook from one of the world’s most prolific audio designers has been updated and amended to make it the leading practical source of information for those interested in linear electronics and its applications, particularly in the world of audio design. 348 pages, in paperback. DESIGNING INTERNET HOME PAGES MADE SIMPLE By John Linsley Hood. First published 1995. Second edition 1999. This book is for anyone involved in designing, adapting and using analog and digital audio equipment. It covers tape recording, tuners and radio receivers, preamplifiers, voltage amplifiers, audio power amplifiers, compact disc technology and digital audio, test and measurement, loudspeaker crossover systems, power supplies and noise reduction systems. 375 pages in soft cover. By John Linsley Hood. First published 1993. NEW SECOND EDITION 1998. $ 65 With this book you can learn the principles and practice of digital electronics without leaving your desk, through the popular simulation applications, EASY-PC Pro XM and Pulsar. Alternatively, if you want to discover the applications through a thoroughly practical exploration of digital electronics, this is the book for you. A free floppy disk is included, featuring limited function versions of EASY-PC Professional XM and Pulsar. 249 pages, in paperback ESSENTIAL LINUX By Steve Heath. Published 1997. 99 $ Provides all the information and software that is necessary for a PC user to install and use the freeware Linux operating system. It details, setp-by-step, how to obtain and configure the operating system and utilities. It also explains all of the key commands. The text is generously illustrated with screen shots and examples that show how the commands work. Includes a CD-ROM containing Linux version 1.3 and including all the interim updates, basic utilities and compilers with their associated documentation. 257 pages, in paperback. 85 $ POST TO: SILICON CHIP Publications, PO Box 139, Collaroy NSW, Australia 2097. OR CALL (02) 9979 5644 & quote your credit card details; or FAX TO (02) 9979 6503 MARKET CENTRE Cash in your surplus gear. Advertise it here in Silicon Chip. FRWEEBE YES! Place your classified advertisement in SILICON CHIP Market Centre and your advert will also appear FREE in the Classifieds-on-the-Web page of the SILICON CHIP website, www.siliconchip.com.au And if you include an email address or your website URL in you classified advert, the links will be LIVE in your classified-on-the-web! S! D E I F I S C LAS EXCLUSIVE TO SILICON CHIP! CLASSIFIED ADVERTISING RATES Advertising rates for this page: Classified ads: $11.00 (incl. GST) for up to 12 words plus 55 cents for each additional word. Display ads: $27.50 (incl. GST) per column centimetre (max. 10cm). Closing date: five weeks prior to month of sale. To run your classified ad, print it clearly in the space below or on a separate sheet of paper, fill out the form & send it with your cheque or credit card details to: Silicon Chip Classifieds, PO Box 139, Collaroy, NSW 2097. Or fax the details to (02) 9979 6503. Taxation Invoice ABN 49 003 205 490 _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ Enclosed is my cheque/money order for $­__________ or please debit my ❏ Bankcard   ❏ Visa Card   ❏ Master Card Card No. Signature­­­­­­­­­­­­ ________________________ Card expiry date______/______ Name _____________________________________________________ Street _____________________________________________________ Suburb/town _________________________ Postcode______________ 94  Silicon Chip FOR SALE RAIN BRAIN AND DIGI-TEMP KITS: 8-station sprinkler controllers. New Digi-temp and Moni-temp use DS1820 sensors. Feature PC data logging, 60 channels over 500 metres. www.mantismicroproducts.com.au ELECTRONIC/MECHANICAL DESIGN AND CONSTRUCTION: we offer a complete design service for electronic and mechanical devices. Most work is done in house and you deal directly with the designers. No job is too small and can be to prototype or “turn key” stage, in one offs or for future production. Simply send us an email at vladimir<at> u030.aone.net.au with your questions or requirements and we will get back to you. COVERT VIDEO SURVEILLANCE Tiny Sub-Matchbox size Wireless Video & Audio TRANSMITTERS from $77 * Pinhole Cameras from $59. Easily concealed in: Mobile Phone Case, Clock, VCR Cassette, Toys, Teddy Bear (Nanny-Cam), Smoke Detector, Ornament, Cap, Cigarette Pack, etc. www.allthings.com.au WEATHER STATIONS: Windspeed & direction, inside temperature, outside temperature & windchill. Records highs & lows with time and date as they occur. Optional rainfall and PC interface. Used by Government Departments, farmers, pilots, and weather enthusiasts. Other models with barometric pressure, humidity, dew point, solar radiation, UV, leaf wetness, etc. Just phone, fax or write for our FREE catalogue and price list. Solar Flair/Ecowatch phone: (03) 5968 4863; fax: (03) 5968 5810, PO Box 18, Emerald, Vic., 3782. ACN 006 399 480. C COMPILERS: everything you need to develop C and ASM software for 68­HC08, 6809, 68HC11, 68HC12, 68­ HC16, 8051/52, 8080/85, 8086, 8096 or AVR: $170.50 each. Macro Cross Assemblers and Disassemblers for above CPUs + 6800/01/03/05, 6502 and 68­HC12 for $88. Debug monitors: $88 for 6 CPUs. All compilers, XASMs and monitors: $5280. 8051/52 Simulator (fast, now incl. 80C320): $88. Try the C-FLEA Virtual Machine for small CPUs, build a “C-Stamp”. Demo desk: FREE. All prices + $5.50 p&p. Atmel Flash CPU Programmer: Handles the 89Cx051, 89C5x and 89Sxx series, and some AVRs in both DIP and PLCC44. Also does most 8-pin EEPROMs. Includes socket for serial ISP cable. $220 $11 p&p. SOIC adaptors: 20-pin $99, 14-pin $93.50, 8-pin $88. Credit cards accepted. GRAN­ TRONICS PTY LTD, PO Box 275, Wentworthville 2145. Ph (02) 9896 7150 or Internet: http://www.grantronics.com.au Time-Lapse VCRs only $799 ! TWO YEAR WARRANTY ! National Service Centres ! Multinational Manufacturer. COLOUR MONITORS 15 Inch 800 + / 17 Inch 1000 + H-line $499 / $599 THREE YEAR WARRANTY. VIDEO CAMERAS DOME COLOUR from $70 ! Mono from $48 ! BULLET from $85 TWO YEAR WARRANTY * DOME 480 Line 0.05 Lux with SONY CCD & ChipSet from $73 * 380 Line from $69 * 450 Line from $90 with 5 YEAR WARRANTY & BLEMISH FREE CCD * COLOUR DOME: 400 Line DSP from $126 * BETTER THAN SUPER-VHS Resolution 600 + Line DSP from $148 * 440 Line from $165 with 5 YEAR WARRANTY & BLEMISH FREE CCD * PINHOLE IN PIR DETECTOR from $111 * COLOUR DSP PIN in PIR CASE from $148 * MINI CAMS from $64 * 420 Line from $83 with 5 YEAR WARRANTY & BLEMISH FREE CCD * DSP COLOUR from $133 * 4 Ch Switcher from $78 * QUAD 1024 H-Pixels from $174 * COLOUR QUAD from $401 * Auto Scanner from $113 * REMOTE PAN & TILT from $239 * DIGITAL PC VIDEO RECORDER SOFTWARE & PCI CARD from $99 * MULTIPLEXER 4 Ch from $640 * REMOTE DIAL-UP, PAGING, WEB-CAM S/W & PCI CARD from $199 * DIY PLUG-IN 20 metre AV Cable Sets from $18 ! UP TO 5 YEARS WARRANTY * OVERNIGHT DELIVERY * www.allthings.com.au RCS HAS MOVED to 41 Arlewis St, Chester Hill 2162 and is now open, with full production soon. Tel (02) 9738 0330; Fax 9738 0334. rcsradio<at>cia.com.au; www.cia.com.au/rcsradio ROLA AUSTRALIA PH/FAX (08) 8270 3175 WEB SITE WWW.BETTANET.NET.AU/GTD CHECK OUR WEBSITE FOR DETAILS ON KITS AND COMPONENTS • • • • Silvertone’s RC Receiver Still the best little performer available! TRANSMITTER KITS AND MODULES AUDIO MODULES COMPUTER INTERFACE KITS RADIO STATION AUDIO SOFTWARE NEW: Our MP3-CD player in short form for $169 inc GST. Includes the following: processor board, front panel display and tactile keypad; just add a case, cables, 12V power supply and a CD-ROM drive. Play CDs and up to 2600 MP3’s from a CDR. Great for car or home. Satellite TV Reception International satellite TV reception in your home is now affordable. Send for your free info pack containing equipment catalog, satellite lists, etc or call for appointment to view. We can display all satellites from 76.5° to 180°. Still only $129.50 AM or $149.50 FM. May be used with most ppm transmitters. This and many other radio control products available from: Silvertone Electronics, PO Box 580, Riverwood 2210. Phone/Fax (02) 9533 3517. www.silvertone.com.au AV-COMM P/L, 24/9 Powells Rd, Brookvale, NSW 2100. Tel: 02 9939 4377 or 9939 4378. Fax: 9939 4376; www.avcomm.com.au Positions At Jaycar We are often looking for enthusiastic staff for positions in our retail stores and head office at Rhodes in Sydney. A genuine interest in electronics is a necessity. Phone 02 9743 5222 for current vacancies. KITS KITS AND MORE KITS! Check ‘em out at www.ozitronics.com HOME CCTV Mono / Colour PAKS Only! $113 / $140 DIY Plug-In to TV / VCR 20 metre Cable, Plug Pack & Camera www.allthings.com.au TELEPHONE EXCHANGE SIMULATOR, SC February 1998. Test equipment without the cost of telephone lines. Melbourne 9806 0110. DIY CCTV PAKS 4 Cameras & Switcher ............... $315 as above COLOUR ................... $419 4 Cams, Switcher/Monitor .......... $433 as above 14" Monitor ............... $461 4 Cams, QUAD & Monitor .......... $602 4 COLOUR & QUAD .................. $797 Time-Lapse VCR only $699 with CCTV Systems 2 Year Warranty ! MORE at: www.allthings.com.au Fully Plug-In DIY Paks with all Cables & Power Supplies ALSO PC Digital Motion / Sound detection & activated Video / Audio Recording systems 08 9349 9413. Need prototype PC boards? We have the solutions – we print electronics! Four-day turnaround, less if urgent; Artwork from your own positive or file; Through hole plating; Prompt postal service; 29 years technical experience; Inexpensive; Superb quality. Printed Electronics, 12A Aristoc Rd, Glen Waverley, Vic 3150. Phone: (03) 9545 3722; Fax: (03) 9545 3561 Call Mike Lynch and check us out! We are the best for low cost, small runs. BASIC COMPILER for PIC micro­ controllers. Developed in Australia. Interactive Windows interface. www. celestialhorizons.com KIT ASSEMBLY ANY KITS assembled/repaired: professional, speedy service. Phone Nev­ille Walker (07) 3857 2752. WANTED PERSON WITH EXPERIENCE / APTITUDE able to fault find & repair PCBs – without diagrams. GENEROUS PKG NEG. Tel John<at>AER (03) 9482 4958 0415 305 470. VERTICAL BLOCKING/OSC transformers. Rola – TV2012, TV204, TV205. Used in old Healing B&W TVs. Write to Frank Stowe, 144 Blinks Rd, Strath­ fieldsaye, Vic 3551. SEPTEMBER 2000  95 Silicon Chip Binders Keep your copies safe, secure and always available with SILICON CHIP binders: they’re cheap insurance! Advertising Index Altronics................................. 66-68 REAL VALUE AT $12.95 PLUS P &P  Heavy board covers with 2-tone green vinyl covering EMC Technologies.......................31 Fluke Australia...........................IFC 4D Systems.................................37  SILICON CHIP logo printed in gold-coloured lettering on spine & cover Harbuch Electronics....................43 Instant PCBs................................95 Price: $12.95 (includes GST) plus $5.50 p&p each (available Aust. only). Price includes GST. Investment Technology................11 Order by phoning (02) 9979 5644 & quoting your credit card number; or fax the details to (02) 9979 6503; or mail your order with cheque or credit card details to Silicon Chip Publications, PO Box 139, Collaroy, NSW 2097. Do you feel left behind by the latest advances in com­puter technology? Don’t miss the bus: get the ’bus! Includes articles on troubleshooting your PC, installing and setting up computer networks, hard disk drive upgrades, clean installing Windows 98, CPU upgrades, a basic introduction to Linux plus much more. Dick Smith Electronics........... 22-25 Emona Instruments.................OBC  Each binder holds up to 14 issues so that you can include catalogs DON’T MISS THE ’BUS Av-Comm Pty Ltd.........................95 Jaycar ................................... 45-52 Kits-R-Us.....................................95 Microgram Computers...................3 MicroZed Computers...................31 Oatley Electronics........................75 Printed Electronics...................... 95 www.siliconchip.com.au SILICON CHIP’S 132 Pages $ 95 * 9 Questronix...................................31 ISBN 0 95852291 X 9780958522910 09 09 9 780958 522910 COMPUTER OMNIBUS INC LUD ES FEA TUR E LIN UX A collection of computer features from the pages of SILICON CHIP magazine Rall Electronics............................31 RF Probes...................................31 R.T.N............................................31 SC Computer Omnibus...............19 SC Electronics Testbench..........IBC Silicon Chip Binders....................96 Hints o Tips o Upgrades o Fixes Covers DOS, Windows 3.1, 95, 98, NT NO W o AVA DIRE ILABLE C SILIC T FROM ON just $ CHIP 125O INC ORDER NOW: Use the handy order form in this issue or call (02) 9979 5644, 8.30-5.30 Mon-Fri with your credit card details. Silicon Chip Bookshop........... 92-93 Silicon Chip Subscriptions...........53 RT P&P Note: price includes the GST. Silvertone Electronics..................95 Smart Fastchargers.....................77 Solar Flair/Ecowatch....................94 Telephone Technical Services.....39 HELP SAVE THE NIGHT SKY! We are losing our heritage of starry night skies. Poor, inefficient outdoor lighting is causing glare and “light pollution”. This wastes energy and increases greenhouse gas emissions. You can help by joining SYDNEY OUTDOOR LIGHTING IMPROVEMENT SOCIETY (SOLIS). SOLIS aims to educate and inform about quality outdoor lighting and its benefits. We also lobby councils, government and other bodies to promote good lighting practice. SOLIS meetings are held third Monday night of each month at Sydney Observatory. Individual membership is $20 pa. Donations are also welcome. Cheques payable to “SOLIS c/- NSAS”, PO Box 214, West Ryde 2114. Email: tpeters<at>pip.elm.mq.edu.au 96  Silicon Chip Truscott’s Electronic World...........77 Vass Electronics..........................31 _____________________________ PC Boards Printed circuit boards for SILICON CHIP projects are made by: • RCS Radio Pty Ltd. Phone (02) 9738 0330. Fax (02) 9738 0334. • Marday Services, PO Box 19-189, Avondale, Auckland, NZ. Phone (09) 828 5730.