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SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings.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.jaycar.com.au Contents Vol.18, No.8; August 2005 www.siliconchip.com.au FEATURES    8 60 Years Of The Atomic Bomb It’s 60 years since the first atomic bombs were used in warfare. Here’s a look at the two designs used and their deadly effect – by Keith Walters 22 Direct Petrol Injection Complex electronics control and direct fuel injection into the combustion chambers can provide big fuel savings. Here’s how it works – by Julian Edgar 102 Hellschreiber Revisited Feedback from readers suggests that it’s not as it appears at first glance PROJECTS TO BUILD Mudlark A205 Valve Stereo Amplifier – Page 30. 30 The Mudlark A205 Valve Stereo Amplifier Want to build a valve stereo amplifier for your hifi system? This class-A2 triode unit produces 20W/channel and has good performance – by David Whitby 38 Programmable Flexitimer It’s easy to build, easy to program and can be set to give two sequential time periods of up to 99 minutes and 59 seconds. What’s more, you can program it for up to 99 cycles of the time periods – by Jim Rowe 61 Carbon Monoxide Alert Carbon monoxide can kill. This sensitive unit not only detects this deadly gas but can automatically control the air vents in your car as well – by John Clarke 74 Serial LCD Driver Programmable Flexitimer – Page 38. Want to use an LCD with your next PC or PICAXE project? Here’s an LCD driver that’s really cheap and easy to connect – by Graeme Matthewson 82 Enhanced Sports Scoreboard This upgraded version of the Professional Sports Scoreboard now includes 2-digit fouls displays for the home and away teams – by Jim Rowe SPECIAL COLUMNS 48 Serviceman’s Log Tracking down a really rotten fault – by the TV Serviceman 70 Circuit Notebook (1) Vertical Sync For The Component Video To RGB Converter; (2) LED Noughts & Crosses; (3) Audio Level Threshold Control; (4) Cheap Pump Controller; (5) DC-DC Converter For USB Supply Or PICAXE Projects Carbon Monoxide Alert – Page 61. 90 Salvage It! Washing machine pressure switches – by Julian Edgar 94 Vintage Radio The AWA Radiola B32 transistor portable – by Rodney Champness DEPARTMENTS   2   4 99 104 Publisher’s Letter Mailbag Product Showcase Ask Silicon Chip siliconchip.com.au 107 108 109 111 Notes & Errata Order Form Market Centre Ad Index Serial LCD Driver – Page 74. August 2005  1 SILICON CHIP www.siliconchip.com.au Publisher & Editor-in-Chief Leo Simpson, B.Bus., FAICD Production Manager Greg Swain, B.Sc.(Hons.) Technical Editor Peter Smith Technical Staff John Clarke, B.E.(Elec.) Ross Tester Jim Rowe, B.A., B.Sc, VK2ZLO Reader Services Ann Jenkinson Advertising Enquiries Lawrence Smith Benedictus Smith Pty Ltd Phone (02) 9211 8035 Fax: (02) 9211 0068 lawrence<at>benedictus-smith.com Regular Contributors Brendan Akhurst Rodney Champness, VK3UG Julian Edgar, Dip.T.(Sec.), B.Ed, Grad.Dip.Jnl Mike Sheriff, B.Sc, VK2YFK Stan Swan 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, Noble Park, Victoria. Distribution: Network Distribution Company. Subscription rates: $83.00 per year in Australia. For overseas rates, see the subscription page in this issue. Editorial office: 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 Publisher’s Letter Some people love valve amplifiers For the many people who love valve amplifiers, our decision to publish the Mudlark A205 stereo amplifier, starting on page 30, will be warmly welcomed. At least, we hope it will. For a long time we have been asked to publish a modern valve amplifier and we have resisted, partly for the reason that no valve amplifier is a match for a well-designed solid state model, and partly because valve amplifiers have been far too expensive, especially when their modest power output is considered. So have we retreated from our belief that no valve amplifier is a match for a well-designed solid-state model? Not for a millisecond! One of the main reasons why we decided to publish the Mudlark A205 is that it is quite an innovative design and quite different from the configuration we would have used, if we had proceeded to produce a state-of-theart valve amplifier. If we had gone ahead, we would have used a class AB push-pull ultralinear output stage, probably preceded by a high voltage op amp driver, and possibly with nested feedback. We would have hoped for a power output of around 50 or 60 watts per channel. Using high quality output transformers, such a design would cost well over $1000, which is the main reason we did not proceed. By contrast, the Mudlark is a lower-powered single-ended design using two paralleled triode-connected beam power pentodes. It also does not use a conventional output transformer but uses a choke as the combined plate load for the triodes, with the output signal being capacitively coupled to a 100V line transformer. Other novel features include positive drive (class A2) via an emitter follower to the grids of the output valves and quite a complex power supply which includes protection for the valves. So the Mudlark A205 is a good design but how does its performance compare with good modern solid-state designs such as our own 15W class A design from July & August 1998 or our UltraLD 100W class AB design from November & December 2001? Well, the solid-state designs clearly beat it on every measured parameter: noise, distortion, frequency response, separation between channels and so on. Nothing has changed there. So why are we publishing the circuit and the full constructional details? Well, in spite of any apparent superiority in the measured figures of solid-state amplifiers, many people will still find the sound of the Mudlark amplifier very satisfying. And so it is. But superior to the above-mentioned transistor amplifiers? Not in my opinion. However, we think the Mudlark A205 design has considerable merit and it comes at a price which, while still expensive, is a bargain compared to many audiophile valve amplifiers available in the marketplace. So have a look at the first of the Mudlark A205 articles in this issue. We don’t agree with everything that the designer, David Whitby, advocates but we are sure that his design will provoke a lively debate. Leo Simpson ISSN 1030-2662 * Recommended and maximum price only. 2  Silicon Chip siliconchip.com.au Innovative • Unique • Interesting • Hard to find products What’s New? Video Capture USB Extender Digital I/O Card Captures from digital & analogue camcorders plus VCR/TV/DVD. Comes with front-access connections. Cat. 23027-7 $299 Use any USB 1.1 device up to 50m away from a PC over inexpensive UTP cable (not included). Cat. 11666-7 $105 A PCI card that provides 48 digital I/O lines and three 16bit counters with a maximum count rate of 10MHz. Cat. 17053-7 $249 2-in-1 Cordless Skype and Normal Phone Make and receive normal voice calls and calls over the Skype network with this cordless phone. Skype is free VoIP software that allows the user to make free PC to PC calls over an internet connection. www.skypephones.com Cat. 10172-7 $220 ATX Power Supply Tester A quick and simple way to test ATX power supplies. Cat 8131-7 $49 Dual ADSL Router Enhance reliability and double your ADSL capacity by using two different ISP's. Cat. 10145-7 $399 Serial to Ethernet Easily web-enable your serial devices. Allows RS232/422/485 devices, including modems to be used over a TCP/IP network. Cat. 15141-7 $259 Wireless LAN Card High speed 802.11G PCI card that suits both 32 and 64 bit slots. A higher gain antenna can be attached. Cat. 11443-7 $129 Serial over Bluetooth This unique unit will allow a serial connection to become wireless using Bluetooth. Cat. 11920-7 $459 Firewire Hub/Repeater Have all your firewire devices plugged in at once with this 6 port hub. Cat. 2847-7 $85 HD Video and Optical Audio Switchbox - 3 In 1 Out Switch between multiple HD/Optical devices with ease. Connectors include component video, stereo and optical audio. A remote control is included. Cat 23032-7 $119 4 Channel Surveillance Card A PCI card with four composite video inputs and one outUSB Serial Ports put for TV display. Comes with Provides two serial ports from basic security software. A one USB port. SDK model is available. Cat. 2852-7 $119 Cat. 3429-7 $299 VGA Splitter/Booster A powered VGA splitter that can run the second monitor up to 80m from the PC. Cat. 3445-7 $199 Removable HD Kit An aluminium frame and tray to convert any standard IDE HD into a removable backup/storage device. Cat. 6802-7 $79 • Generally delivered next day • Not sure what product you require? Call us for friendly advice! Cable Tracer This stylish laser scanner is great for small to medium sized retail outlets. A stand is available. Cat. 1008039-7 $399 Features a single or multitone signal. Comes with two test leads and a 4-conductor modular cable. Cat. 11520-7 $129 ask<at>mgram.com.au 02 4389 8444 www.mgram.com.au KVM with Sound RS232 to RS485 Convert RS232 to RS485. Runs up to 1200m and works in half or full duplex. Cat. IC485S-7 $129 Windows Based Terminal Cash Drawer Can be attached to Epson/Star/Citizen/Posiflex parallel receipt printers. Cat 8897-7 $199 Console Sharer Allows two workstations to operate the one PC. Supports PS/2 keyboard and mouse with VGA monitor. Cat 11667-7 $139 PCMCIA Serial ports No serial ports on your new laptop? Easily add two ports with this PCMCIA card. Cat 2726-7 $269 This tiny WBT can attach to the VESA mounts on a LCD monitor. It supports RDP and emulates SCO, DEC, Wyse etc. Cat. 1239-7 $649 Magnetic Card Reader Reads tracks 1 & 2. Has a keyboard wedge connection for easy installation. Cat. 8768-7 $259 Allows one keyboard, monitor and mouse to control two PCs. Switches the sound as well as the KVM. Includes 1.2m cables. Cat. 11669-7 $89 Mini 88 key keyboard Comes with a laptop style touchpad. A great space saving replacement for mouse & keyboard. A cordless model is available. Cat. 8751-7 $139 Phone: 02 4389 8444 Dealer FreeFax: 1800 625 777 inquiries ask<at>mgram.com.au welcome siliconchip.com.au www.mgram.com.au August All prices subject to change without notice. For current pricing visit our website. Pictures are indicative only. 2005  3 SHORE AD/MGRM0805 Laser Barcode Scanner MAILBAG Mixed equalisation preamps have delicious sound I read with interest the comments in the June 2005 issue of SILICON CHIP, about the phono preamp described back in July 2002, utilising passive equalisation. Having built that preamp circuit shortly after its publication, I can confirm the sort of sound, typical of full passive equalisation designs. Subjectively anyway, its overall distortion seemed quite acceptable and not excessive. The equalisation may not have been absolutely accurate, however this is not necessarily a major condemnation, as many “high end” phono preamps are “biased”, apparently deliberately, to give a specific sound, something regarded highly in some audio quarters! I was somewhat bemused by SILICON CHIP advocating a conventional feedback circuit design approach. As a self-confessed audiophile and vinyl-phile, and having looked at phono preamp design in considerable detail and also having built quite a few different designs, my firm opinion is that conventional feedback designs, tend to sound dull and lifeless with poor transient response, although that approach admittedly, can produce potentially very low distortion and accurate equalisation. My preferred approach is a combination of “active” low frequency and “passive” high frequency equalisation. Increasingly, on the internet and elsewhere, this sort of approach appears to be gaining popularity for its sonic and other merits. In recent times, I have built several phono preamps of different circuit design but using this general circuit approach of split active/passive equalisation and as a general rule, I find them not only superb “specs-wise” but sonically, they are delicious sounding. The best of both worlds? Yes, I think so. Felix Scerri, VK4FUQ, Ingham, Qld. Comment: your comments about transient response are curious, given 4  Silicon Chip that, regardless of whether passive or active equalisation is used, an RIAA preamplifier is effectively a big lowpass filter or integrator (with a more or less constant -6dB/octave slope). In other words, the transient response is largely set by the RC time-constants and not by the circuit configuration. If a phono preamp sounds dull and lifeless (or alternatively, bright and lively), that suggests that it has incorrect equalisation or maybe the input loading is not optimum for the particular magnetic cartridge. We do not feel qualified to comment on preamps with “delicious sound”. Colour TV nostalgia enjoyable I would just like to say how much I enjoyed reading the two-part article on the “Start of Colour TV in Australia” in the March and April 2005 issues of SILICON CHIP. This brought back lots of memories, especially the sections on the Philips and Kriesler sets. At the time of startup of colour in Australia, I was working in the North Queensland distribution warehouse for Kriesler TV and Audio products which included the first colour chassis, the 59-1. We would receive regular semitrailer loads from the factory in Sydney and then they would be pre-sale tested before being despatched to retailers around North Queensland. We kept a large range of spares for these sets and regularly had to supply service shops around the district with parts that had failed under warranty, especially the BU126 transistor in the power supply and the BU108 line output, along with the triplers. I recall that many parts for the first Kriesler and Philips sets were common and interchangeable. Thanks again for a great read. Warren Ray, Townsville, Qld. DVD region codes I saw your reference to DVD region coding in the article on laptop PCs in the June issue. You can get rid of this annoyance by using a small program called DVD Region Free which is available from http://www.dvdidle.com/download. htm Its costs are not that much in the overall scheme of things and if you want to play other zone disks, it is one way to do so permanently. This software allows you to play DVDs on your PC with no change to the drive’s region setting, bypassing the setting as it is set in the drive properties. It also allows you to burn disks “region free”. As far as stand-alone DVD players are concerned, regional encoding is a thing of the past on many models. I will not buy a player unless it will play my disks which I legitimately purchased in or from the USA. Many of the music videos I have are simply not available here and hence a Zone 4 disk does not exist. The player must be also capable of playing a “slab of burnt toast” if I put one in. By this I mean as far as DVD, DVD-R, DVD+R, CD, Audio DVD, MP3, Kodak CD, etc, it must play all formats. Also, my price limit for a player is no more than $100. If it lasts two or three years and then dies, so be it. I’ll go and get another one. Having had problems with players before, I now take a disk that I’ve burnt, which I KNOW should play, to the store when I get a new player. I test it in the player to make sure it’ll play my burnt disks and then buy THAT player – even if it’s the display model! Hey – if it says on the box that it’ll play DVD-R, then it should do so without any sticking, stalling, etc. And a note on burning: burning siliconchip.com.au DVDs at maximum speed is one way to get drink coasters on many standalone players. It’s similar to burning audio CDs over about 12 or 16 times. Over this speed, they play on your PC but on your portable they can skip and stick like there’s no tomorrow. Slow the burn speed down and they play OK on just about everything. The same goes for DVDs. 2x is the maximum at which I’ll burn a DVD. Check out the region-free software – it works like a treat! Brad Sheargold, Collaroy, NSW. DVD region-free In his review of laptops in the June 2005 edition, Ross Tester complains (rightly) about regional coding on DVDs and DVD drives. There are software packages available that get rid of this nonsense. I use one called “DVD Region+CSS Free”. Once it is running, my PC will play a DVD from any region. Very useful as I import – through Amazon (USA and UK) – DVDs that are just not available in Australia. You can get details of this software from www.dvdidle.com. There is a 30-day trial version available and the paid version costs $39.95 US. Nick Booth, Epping, NSW. Coolmaster cannot maintain a constant temperature I think that there is a major problem with the Wine Cooler application of your Coolmaster project, featured in the June 2005 issue. As I understand it, the actual temperature that wine is stored at is not crucial but it is important that this temperature is constant. So how will the Coolmaster maintain, say, a temperature of 15°C when the outside ambient temperature is 10°C? It will not, as in its present form the Coolmaster is only suitable for maintaining a constant temperature when the ambient temperature is above the fridge temperature. The answer would be to add a fan and a heater inside the fridge. This heater could be left on continuously or be switched on when the compressor is not running. We have a product that would fit this application as it can control siliconchip.com.au cooling and heating. See ZC0606 at: http://www.oatleyelectronics.com/ bcorner.html. We also have a mechanical controller that would be suitable for the refrigerator application as its minimum setting is 4°C. Branko Justic, Oatley Electronics Pty Ltd, Oatley, NSW. Comment: it is true that the Coolmaster will not maintain a fridge’s internal temperature at 15°C or indeed, at any temperature above the room temperature. We assume that the same comment would apply to most commercial wine fridges. However, we do not think that is generally a problem with storing wine in most houses and a drop in room temperature to 10°C or lower is not likely to cause a degradation in the wine. Photocopiers going to waste I’d like to add to the comments from Todd Noyce in the June Mailbag concerning photocopiers. Earlier this year, I was at a computing and AV auction here in Brisbane. Among the lots on offer were a number of photocopiers, including one model that I had used through work when they were new about six years ago. When they came up, there were no bids and a number of them were passed in, not even attracting interest at $5 (it was quipped that there was probably this value of paper still in them). These machines had been “state of the art” and truly capable, and cost as much as a small Japanese motorcar when new. Apart from the bulk of these machines, I seem to recall that one of the models offered had a gross weight, including collator and recirculating automatic document feeder, of about 70kg. But as our previous correspondent mentioned, they are a treasure trove of electronic and mechanical bits and pieces. Any one with an interest in tinkering would be in heaven with one of these to recycle. Of course, the machines were offered in running order so any purchaser would’ve soon got their money’s worth from them from their original function. It was a pity that I had neither the room at home for one, nor the room in my car to bring one home. Atmel’s AVR, from JED in Australia JED has designed a range of single board computers and modules as a way of using the AVR without SMT board design The AVR570 module (above) is a way of using an ATmega128 CPU on a user base board without having to lay out the intricate, surface-mounted surrounds of the CPU, and then having to manufacture your board on an SMT robot line. Instead you simply layout a square for four 0.1” spaced socket strips and plug in our pre-tested module. The module has the crystal, resetter, AVR-ISP programming header (and an optional JTAG ICE pad), as well as programming signal switching. For a little extra, we load a DS1305 RTC, crystal and Li battery underneath, which uses SPI and port G. See JED’s www site for a datasheet. AVR573 Single Board Computer This board uses the AVR570 module and adds 20 An./Dig. inputs, 12 FET outs, LCD/ Kbd, 2xRS232, 1xRS485, 1-Wire, power reg. etc. See www.jedmicro.com.au/avr.htm $330 PC-PROM Programmer This programmer plugs into a PC printer port and reads, writes and edits any 28 or 32-pin PROM. Comes with plug-pack, cable and software. Also available is a multi-PROM UV eraser with timer, and a 32/32 PLCC converter. JED Microprocessors Pty Ltd 173 Boronia Rd, Boronia, Victoria, 3155 Ph. 03 9762 3588, Fax 03 9762 5499 www.jedmicro.com.au August 2005  5 Mailbag: continued One prize that I came away with, and I hope that maybe a reader may be able to tell me more about it, is a Philips LBB 1149/00 8-channel audio mixer. It appears to be a professional level mixer but I have been unable to identify it specifically. I have tried some web searches and spoken directly with both Philips and Thompson, with no answers to date. I believe that the unit is less than 15 years old and is in, apparently, good condition. Perhaps one of your readers may know something of the history and true performance of this mixer? Campbell Sharp, Yeronga, Qld. Possible cure for STB electrical interference Following Robert Parnell’s letter the July 2005 issue about impulse noise affecting set-top boxes, you might be interested in how I solved my electrical interference problems for my Digital STB. The glitching on my reception was quite intolerable (every few seconds), so rather than go back to analog I sought a solution. I put a 1.8m earth stake in the ground and connected it to the antenna system signal ground, just before the distribution amplifier. It made a huge improvement and I have no quad-shield coax! One possible explanation is that cleaning out the LF garbage in the coax braid has removed spikes that were sufficient in amplitude to drive the tuner front-end into non-linear overload. Firstly, if there is any part of the VHF spectrum that you can filter, then do this. I fitted a -50dB VHF filter (Kingray DPO-UV diplexer) and this made a difference but I am lucky because all my stations are UHF only. The best general alternative is a triplexer that can be used to filter out all non-TV frequencies and any unused TV bands. Electrical trade wholesalers such as Lawrence and Hanson, Middendorps, Active, etc sell 1.8m copper-plated earth stakes for about $20. I located mine in the wettest part of the garden, taking note of underground gas pipes, etc. The location was a shade-clothed 6  Silicon Chip fernery with a built-in mist-spray watering system and it also happened to be close to where the TV distribution amplifier is located. I also purchase 6m of some very heavy mains (greenyellow) insulated copper wire. I soldered the wire and clamp that comes with the stake and soldered the other end to the shield/braid at a splitter just before the distribution amplifier. (Leave out the soldering bit if that is too hard but it does help reduce the earth path impedance). This arrangement almost completely eliminated audio/video drop-outs, pixellation and “no signal” on my digital tuner. I would not recommend to anyone to try using the mains earth for the antenna as this is “very dirty” and could make matters worse. Those people with STBs that run extremely hot might also benefit from my clean earth idea as the problem is eliminated if you don’t have isolated TV outlets. Before I earthed my antenna it “measured” 2000V! This is fairly common but not usually dangerous and is caused by leaky TV sets. But it does cause tuner modules to run very hot. Neil Hecker, Morwell, Vic. Comment: the earth stake sounds like it is worth a try. As a bonus, it would also give some lightning protection to the set-top box and TV. Big energy shortages looming I wish to raise a few points about the infrastructure debate that currently has the politicians bubbling. There are a few simple points that there is data to support: (1) Our population has increased by millions since we last built an AC mains generating station in Australia. (2) In some states, 50Hz is regularly not maintained to “support capacity problems”. (3) The number of mains-powered devices that are available has proliferated in the last 20 years. Witness the number of powerboards (6, 8 even 10-outlet that are sold. Try and rewire an old Victorian double brick house. Each room has only one power point and except for large rooms, only one light. Home-theatre systems, computers and home air-conditioning did not exist in the 1920s. Every year in Victoria, we have power shortages at peak times; eg, mid-winter and mid-summer. There is much finger-pointing but NO doing (that is visible). This goes for the water supply and other infrastructure. I have done some of the research and the data is unsettling at best. We do not have the generating capacity of a modern developed country and nor do we have fresh water or conservation of water programs adequate to support industrial growth nor the projected population growth of the Federal Government. Jason Walters, Melbourne, Vic. RFID sensor makes a great cat door Thank you for designing the RFID module featured in the June 2004 issue. I adapted its design to make a pet door which has now been in service for about nine months now. No longer do I have to put up with the smell of cat spray around the house and as a bonus, bandicoots can no longer get in the house and spread the cats’ food around the laundry. I did modify it slightly with a bigger ID20 module to increase its range to 15cm and I adapted a commercially made electric cat door which relied on reed switches and a rather large magnet, attached to the cat. I mounted the sensor module in the plastic housing of the door and have the electronics in a wall box nearby. It fires the solenoid in the cat door to open it. Lloyd Jury, via email. Photocopying cost to SILICON CHIP With regard to the editorial in the June 2005 issue on the topic of photocopying, I would say that you are spot on with regard to the amount of photocopying of articles of various journals that goes on and I do sympathise. There appears to be little understanding of the rules in this area and that includes myself. I hear different siliconchip.com.au accounts from my colleagues regarding acceptable use such as “it’s OK to photocopy just one article” or “one chapter of a book is legally allowed”. I have heard “10% of a book is legally allowed”. Maybe in your next editorial you could briefly describe your understanding of the limits to which training organisations can legally copy materials and when such use would be a copyright infringement. I’m sure in many cases the reason is simply ignorance or old information. I have really enjoyed the Picaxe articles you have published recently. I find this a remarkable device and I’m planning to get a few experimenter kits as soon as Microzed gets itself back on its feet. Richard Bailey, Regency Institute of TAFE, Regency Park, SA. VU meter makes good ammeter Because VU meters are very sensitive, it is easy to use them to measure siliconchip.com.au current up to, say 5 amps. All you need is a suitable shunt. Take a length of twisted pair from some Cat-5 cable, solder them together at one end and to the meter terminals at the other. To “fine tune” the shunt, use a suitable power supply, a variable load and a digital multimeter to do the calibration, then use a utility knife blade to “short” across the twisted pair by cutting through the insulation at various points until you get the required FSD and current reading on the multimeter. Finally, trim and resolder the two ends back together. I was able to make a 5A meter using a 17cm length. How cheap is that? Robert Paterson, via email. Open-wound jug elements not usable on DC With reference to your shunt-regulating battery charger article in the June 2005 issue, mention was made of using the jug elements, as described, for heating water. Doing this is likely to result in short element life due to electrolysis and possibly even accelerated corrosion of the water tank. Heating elements of open construction as used in electric jugs are only suitable for AC operation. This is why in areas where DC mains have been common (eg, the UK until the 1960s), sealed elements have been used. In fact, I recall a story where an electric jug of the open element type was used in Sydney’s CBD during the 1940s, when DC mains were used by some consumers. The result was that the boiled water had an unpleasant taste due to the “electroplating” taking place. Note also that 12V coffee makers/ immersion heaters use a sealed element for this reason. If a water heater dummy load is going to be used for this project, it would be better to use a parallel combination of the cheap 12V immersion heaters as sold by auto accessory and $2 shops. For a 24V system, series parallel combinations would be used. John Hunter, St Leonards, NSW. August 2005  7 On August 8th 1945, the world woke to the startling news that two days earlier, much of the Japanese city of Hiroshima had been destroyed by a single bomb dropped from a US aircraft. A few days later came the news that the city of Nagasaki had suffered a similar fate. Shortly after, the Japanese surrendered. 60 YEARS of the ATOMIC BOMB 8  Silicon ilicon Chip hip by Keith Walters siliconchip.com.au M uch has been written about the first atomic bomb to be used in warfare – and it is interesting to compare the newspaper reports of the time with more recent historical descriptions of the same event. Recent accounts reports tend to dwell on the terrible death toll . But that wasn’t really what the citizens of the time were so shocked about. After all, at that point in the war there were almost nightly raids on Japanese cities by huge fleets of B29 bombers, which inflicted similar amounts of damage with similar casualty figures. The after-effects of radiation and fallout are often mentioned these days but these weren’t really understood at the time. An awful realization No, the real shock was that here at last was an explanation for one of the greatest puzzles of WWII: What was the purpose of the V2 rocket? Toward the end of WWII the Nazis launched approximately 5,000 V2 rockets, mostly aimed at Antwerp and London. At first sight, the V2 sounds like a formidable weapon: carrying a one-tonne payload, it could climb to a height of about 100km and then fall back to Earth at supersonic speed, seemingly appearing out of nowhere before destroying one or at most, two buildings. As a military weapon, the V2 was ludicrously inefficient. They cost more to build than a conventional bomber, which could deliver much more explosive punch, far more accurately, and with a more than half-decent chance of coming back for another load! Terrifying though the V2 may have sounded, the vast majority of them simply failed to hit anything important. But after August 6th 1945, the whole world realised what the US and British military had known for some years: theV2 was merely one part of a radical new weapons system, the other part being the atomic bomb. Armed with a nuclear warhead, the V2’s targeting accuracy would cease to be an issue! Heinrich Himmler (in charge of Hitler’s dreaded SS) had actually made occasional references to such so-called “miracle weapons” which could “destroy London or New York with a single stroke.” Fortunately, as it turned out, building a workable nuclear weapon, particularly one that a V2 could carry, was far beyond the capabilities of the Nazi Military Industrial complex. But nobody had any way of knowing that at the start of the war. Manhattan Project As it was, the amount of industrial and scientific muscle that was applied in the USA to the top-secret “Manhattan Project” is simply unbelievable. Over half a million people worked on the project at one time or another, the vast majority having absolutely no idea what they were working on! The true cost will probably never be known, as several large corporations donated large amounts of time and resources at cost or for free, and the thousands of engineers and scientists were rarely paid overtime. An oftenquoted guesstimate is about $US30 billion (about $A42 billion) in today’s currency. Another little-appreciated fact is that the two bombs that were dropped used two completely different technologies. The Hiroshima device used relatively simple “gun-type” bomb construction but required a staggering amount of equipment and time to produce the highly enriched uranium it needed. This photograph of the damage to Hiroshima is also historically significant because it is signed by Col. Paul Tibbets, Pilot of the “Enola Gay” which dropped the first Atomic Bomb on Japan on August 6th, 1945. siliconchip.com.au August 2005  9 The Nagasaki device used plutonium, which costs far less to manufacture but the sophistication of the necessary implosion detonator device is, even to this day, far beyond the technological capabilities of most countries. Virtually all of this happened within a space of about three years, with most of the critical work done in the final 12 months! Why? Much has been written over the last 60 years about the actual reasons the atomic bombs were used on Japan, a large part of it being speculation presented as fact. One fact often overlooked is that the people making those decisions were all born in the much tougher world of the 19th century. They had already lived through one world war and the worst economic recession in recorded history. The world was a very different place then. At the time, most Americans knew virtually nothing about Japan or its people, apart from the single fact that the Japanese air force had launched an unprovoked attack on Pearl Harbour. The Allied Powers were also coming to terms with a massive humanitarian crisis in Europe, most of it the result of a drawn-out and futile war that the recently defeated Axis powers had effectively lost years before. So one of the factors would have been the growing realization that without an order of unconditional surrender from the Japanese Top Brass, there seemed little possibility of any quick end to hostilities in the Pacific. There was already a massive aerial bombing campaign under way that was expected to have destroyed all of Japan’s military manufacturing capability by early 1946, carried out by huge fleets of B-29 bombers. Although there was little question that the Japanese military would soon cease to be a major threat, there was no telling how it long it would be before the Pacific would again be safe for shipping. The Japanese soldiers’ (or probably more correctly, their officers’) “fight-to-the death” Bushido code was already resulting in unacceptably high Allied casualties just trying to secure some small Pacific islands; the death toll from an invasion of the Japanese 10  Silicon Chip mainland would be immeasurably higher. Hiroshima: August 6 1945 The only thing that seemed likely to change the situation was direct intervention by the Emperor, and the only thing that might prod him into such an unheard-of breach of protocol would be a massive display of overwhelming force. Originally a “demonstration” explosion in Tokyo harbour had been proposed but perhaps surprisingly this was rejected on the basis that it The blast from a nuclear bomb normally extends far probably would not look beyond the fire zone. But Hiroshima suffered from a all that impressive. It huge number of fires fed by gas leaks, exacerbated by the light construction of the majority of buildings. might sink a few boats and cause a mini-tidal wave, but overall the damage inflicted would plicity of the design, and the shortage probably be relatively slight. of further U235 supplies, they decided A list of potential military targets that testing of the Little Boy design was drawn up, the list gradually dwin- might be an unnecessary luxury. dling as city after city was destroyed The final “combat ready” Little by conventional bombing raids! Boy assembly was 3.2 metres long, By August 1945 there were only two 71cm in diameter and weighed about working atomic bombs actually avail- 4 tonnes, most of this being made able, one of each type, and although up by the steel tamper backplate. By there was some talk of reshaping mid-July the major bomb components Little Boy’s U235 core to make four had been shipped out to Tinian Island more implosion bombs, the War Office in several sections on the USS Indievidently decided it didn’t want any anapolis, under intense secrecy. The further delays. Due to the relative sim- uranium-containing sections were A few moments ago, there was a city under there. About 30 seconds after the explosion (8.15.15am local time on August 6, 1945), the Enola Gay circled Hiroshima at 30,000 feet – and the mushroom cloud was already above them. The city itself was already completely obscured by the thick black smoke seen at the bottom of the picture. siliconchip.com.au photographs was simply due to conventional fires caused by burning gas jets when large numbers of wooden factory buildings collapsed. More substantial brick and stone structures even directly under the blast were still left standing, although no one inside them would have survived. Actually the initial death toll wasn’t all that different from what had already been experienced in dozens of conventional bombing missions, although admittedly those didn’t have the added later complication of radiation exposure. Visitors to both sites reported that weeds and grass had started to sprout again within a few days, so the effect was more like that of a savage forest fire. Nagasaki: August 9 1945 Backup-plane view of the mushroom cloud over Nagasaki, August 9, 1945, Nagasaki was in fact the backup target, the primary target of Kokura being obscured by clouds. So too was Nagasaki – but it “earned” its place in history. flown out separately on three C-54 transport planes. The projected date of the first bombing mission was August 1 1945, with a second mission ten days later on August 11. However, bad weather delayed the first mission until August 6. Although their primitive on-board radar systems could establish the general location of a city, if there was substantial cloud cover, there was simply no way of finding your actual target! The B-29 “super fortress” finally selected was piloted by 30-year-old Colonel Paul Tibbets and christened “Enola Gay” after his mother. Tibbets is still alive incidentally; you can read a recent interview with him at www.guardian.co.uk/g2/ story/0,3605,769634,00.html You can also visit his website www. theenolagay.com The co-pilot was Captain Robert Lewis, and the weapons specialist supervising the bombing was US Navy Captain William “Deke” Parsons. The 12-man crew also included an assistant weaponeer, a bombardier, a navigator, two radar specialists, two flight engineers, a radio operator and a tail gunner. The bomb was assembled on Tinian Island and checked out on August 5th ready for a 2:45 AM takeoff the next day. It was supposed to be left in fullyoperational form but Parsons removed siliconchip.com.au the explosive charge from the gun for re-fitting immediately after takeoff, in case of a crash. The mission went off without a hitch, unlike the trouble-plagued Nagasaki mission a few days later. At 7:30AM Hiroshima was in plain sight and so the bomb’s electronic systems were activated. (Because of the enormous power drain of the valve-based electronics, the bomb could not be armed for much more than two hours before its intended use). At about 8AM local time the “aim point”, the Aioi Bridge, was lined up by Parsons. About 15 minutes later, Little Boy was released and when the Enola Gay was safely clear, a 1.3GHz arming signal was transmitted, switching on the bomb’s main control electronics. When the bomb fell below 7,000 feet, the onboard radar altimeters were enabled by the barometric safety switch and when they detected a height of 1,900 feet above ground, the cordite explosive charge was detonated. The U235 “bullet” then slammed into the tamper/target in less than six milliseconds, producing the nuclear explosion only about 150 metres short of the aim point. Most accounts of the event report that the city was completely destroyed by the initial explosion but this is something of an exaggeration. Most of the devastation seen on later The actual Fat Man bomb assembly was fitted into a relatively conventional bomb casing with the necessary remote control electronics and its batteries. The whole assembly was 3.25 metres long, 1.5 metres in diameter and weighed about 4.5 tonnes, more than half of this being the TNT explosive lens system. The B-29 selected for the mission was had already been named “Bocks Car” after Frederick C. Bock, the man who usually piloted it. It was piloted for the Nagasaki mission by Major Charles Sweeney. The intended target was the massive arsenal complex at the city of Kokura, where the bulk of Japan’s weapons R&D and manufacture was carried out. Things started to go wrong right from the start. (Ironically, the only thing that worked flawlessly was the bomb itself, despite the necessity of skipping many of its final checkout procedures due to the revised timetable)! Soon after takeoff they discovered that the fuel pump attached to the auxiliary tank was not working, and although this did not necessarily mean they had to abandon the mission, it severely limited the amount of time they could spend searching for their target. When they reached Kokura, the city was hidden in clouds so thick that they lost sight of the other two escort/decoy B29s. After three fruitless passes over Kokura, Sweeney decided to try for Nagasaki, the only other target in range. There was only enough fuel available for a single pass over Nagasaki, and since they would have to jettison Continued on P14 August 2005  11 ANATOMY OF THE ATOMIC BOMBS The basic theory of an atomic fission bomb is well known to most scientifically literate people these days, and was certainly understood by nuclear physicists by the late 1930s. Essentially, if a sizeable quantity of a suitably radioactive material could be suddenly crushed together into a small volume, the probability of any particular neutron colliding with another nucleus and releasing two or more further neutrons would be greatly increased. With a suitable “fissile” material the classic runaway chain reaction would take place resulting in almost instantaneous splitting of a large proportion of the nuclei and an enormous burst of heat and radiation. “Little Boy” At first, the only material that seemed workable for a bomb was the scarce uranium isotope U235, which has a nucleus consisting of 92 protons and 143 neutrons. Calculations showed it would need to be refined (that is separated from the other uranium isotopes) to at least 90% purity, otherwise the more radioactive U238 atoms would cause the critical mass to “jump the gun”, destroying the bomb after only a very small percentage of atoms had fissioned. It was quickly realised that the greater the amount of compression that could be applied to the fissile mass, the smaller the minimum amount that would be required to produce a true nuclear explosion. However the amount of compression that could be practically applied was heavily dependent on the physical properties of the strongest available materials at the time. The only workable approach envisioned in the early 1940s was a “gun” design where the fissile material is made in two separate pieces which are 12  Silicon Chip slammed together by an explosive charge. The limitations of tungsten carbide, the strongest workable material at the time, meant that a practical weapon would also need about 65kg of the 90% pure U235 – there was simply no conceivable method of applying sufficient compression to any smaller amount. As it turned out, only one such “gun type” uranium weapon was ever built, codenamed “Little Boy”, the design becoming obsolete before the weapon was ever tested. Bomb mechanism The actual bomb mechanism was made from a modified anti-aircraft gun. The 65kg fissile mass was made into two distinct sections: a 100mm diameter “plug” that would be fired down the barrel of the gun and a series of 100mm diameter rings (constructed like ferrite speaker magnets) that the plug would “collect” on the way. The 75mm barrel was machined out to 100mm and a conventional explosive charge would fire the U235 plug toward the “tamper”. The tamper consisted of a tungsten carbide plate mounted in a 2.5 tonne steel block. This steel block and the gun barrel had matching threads cut into them so they could simply be screwed together. When the explosive charge was fired the U235 plug and the collected uranium rings would smash into the tamper, producing a modestly compressed critical mass of uranium vapour, hopefully compact enough to start a runaway chain reaction. The “production” bomb’s control mechanism was amazingly sophisticated for something built 60 years ago. The bomb received its final arming signal (after it had been released from the aircraft), via a then state-of-the-art 1.3GHz radio control system. The bomb also contained a newly developed radar altimeter and a “fail-safe” atmospheric pressure switch, which prevented the bomb from detonating above 7,000 feet. Only one operational bomb of this type was ever produced, since by the time it was ready for combat use, the much more technically demanding but inherently more efficient plutonium implosion system had been successfully tested. Five complete “Little Boy” bomb mechanisms were actually built by August 1945 but there was only enough U235 for one of them. As far as operational safety was concerned, Little Boy was a ludicrously unsafe weapon! Anything that could have accidentally ignited the cordite charge (a plane crash or similar vehicle accident) could have set off a full-yield nuclear explosion. Although it was always transported with the explosive charge removed, it was only later realised that the design had no provision for waterproofing. Any water entering the device (in a shipwreck for example) could have acted as a crude moderator for the highly enriched uranium. While this could not produce a true nuclear explosion, it still would cause massive damage to the surrounding area as well as delivering a lethal dose of gamma rays and Here’s something you can never see again, because it disappeared in less than the blink of an eye. This is a photo of the actual “Little Boy” atomic bomb, ready for loading aboard the Enola Gay on Tinian Island, August 5, 1945. An interesting aside – one which would undoubtedly have changed history: would you believe that just four days after unloading its topsecret cargo on Tinian, the US aircraft carrier “Indianapolis” was sunk by a Japanese submarine? siliconchip.com.au neutrons to any crew members nearby. Created under the pressure of wartime emergency, the Little Boy bomb was a very inefficient design, in that less than 2% of the 65kg of U235 actually underwent useful fission. The superior compression system used on Fat Man allowed a similar explosive yield (18 - 21kt) using only about 6kg of plutonium. Another piece of history: “Fat Man” being transported to the B29 bomber “Bocks Car” for its oneway journey to Nagasaki, August 9, 1945 “Fat man” So the uranium bomb that was dropped on Hiroshima (Little Boy) was really something of an “orphan”. It was originally undertaken as the atomic fission device “most likely to work”, on the basis of what was known in the early 1940s. To the best of anyone’s knowledge at the time, the only material in existence that was suitable for building a fission bomb was uranium 235. However, as the initial research got underway, it was realized that a then-theoretical element with 94 protons and 145 neutrons might also be suitable. This was verified after a minute sample of the element was eventually created by bombarding U238 with a high-speed neutron beam from an early model cyclotron. Ultimately, this element was named “plutonium”. But while the scientists soon realized that it might still be possible to base a bomb design on plutonium, it would require the development of a vastly more sophisticated explosive trigger mechanism. No tamper made from any known substance would be anywhere near strong enough to withstand the force of the collision that would be necessary to initiate successful plutonium fission. The only solution was to shape the plutonium into a hollow sphere and completely surround it with a spherical layer of high explosive. To produce a precisely spherical shock wave, thousands of experiments were carried out with “explosive lenses” made from fast and slow-burning TNT mixtures. The individual explosions had to be synchronised to within nanoseconds, and so conventional hot wire electrical fuses could not be used. Instead, special “exploding wire” detonators were developed. These were combined with sophisticated spark-gap triggers driven from a newly developed portable regulated 8,000V DC power supply made by Raytheon. The spark gaps were all fed from a network of precision RC networks with exactly the same time-constant. 32 large high voltage capacitors were needed, and the capacitor/spark gap assembly alone weighed siliconchip.com.au over 200 kilograms! Apart from all this, the scientists and engineers had only a few months to learn the entire metallurgy of the brand-new element, plutonium. Initially they had problems with the plutonium sphere halves warping after casting and machining, until they discovered that an alloy of 3% gallium and 97% plutonium was dimensionally stable. Although, like uranium, plutonium 239 is only weakly radioactive in the “unmoderated” state, chemically it is an extremely toxic substance and spontaneously bursts into flame when exposed to air. All the machining had to be carried out in an atmosphere of nickel carbonyl gas, which plated any newly exposed surfaces with a protective layer of nickel. The final wartime implosion-type bomb used about 2.5 tons of TNT-based shaped charges precision-fitted around a series of nested shells of various materials. (See diagram). The entire assembly was housed in a spherical aluminium alloy shell about 100mm thick and 1,500 mm diameter. There were 32 separate explosive lens assemblies, 20 hexagonal and 12 pentagonal, in the same pattern as a soccer ball. Each assembly consisted of two precision castings of fast-burning and one casting of slow-burning explosive. The slow-burning segment fitted into a conical cavity in the larger of the fast-burning pieces, and a further piece of fast-burning explosive was fitted under this. The actual plutonium “pit” was machined into two precision hemispheres that formed a hollow sphere 90mm in diameter (about the size of a cricket ball). The 20mm polonium/beryllium neutron initiator fitted precisely inside the hollow centre. Surrounding the pit was a 70mm thick “tamper/reflector” made from natural uranium. Its purpose was mostly to keep the pit from rebounding before the full fis- sion reaction could be completed, but it also served as a neutron reflector to enhance the chain reaction. Also a small part of the “yield” of the bomb (about 20%) would come from fast fission of the tamper. Surrounding the tamper was a 115mm “Pusher/Neutron absorber” shell made from a boron/aluminium alloy. This was actually part of the mechanism that “tuned” the implosive shock wave, although what the neutron absorption function of the boron actually accomplishes has never been made entirely clear. The shock waves would move more slowly through the lightweight aluminium than they would through the uranium, and the timing was such that any reflected energy would be returned to the core just as the actual chain reaction began, something after the fashion of a Yagi antenna. For safety, a 20mm hole was cut through the plutonium pit and the pusher and tamper shells to allow the neutron initiator to be fitted just prior to combat use. For transport, a dummy sphere of cadmium removed any possibility of a chain reaction. Removable precisionmachined aluminium and uranium plugs allowed this to be withdrawn and the initiator fitted in its place. Each of the 32 exploding-wire detonators was connected to an SO239 “UHF” socket, the same type that is still found today on AM CB radios. (In those days, “UHF” meant pretty much anything above about 50MHz!) Since the detonators had to be fired within +/-10 nanoseconds of each other, 32 precisely matched lengths of coaxial cable were required. (Ironically, the necessary polythene dielectric co-ax was yet another technology that just “happened along” at the right time!) August 2005  13 Perhaps more by (bad?) luck than management, the Mitsubishi arms plant in Nagasaki became ground zero. Here’s what was left of it. the bomb anyway if they were going to make it back, the bombardier decided that if necessary they would attempt to aim the bomb using the onboard radar system. Nagasaki turned out to be covered in even thicker clouds than Kokura but just as they were about to release the bomb for a “pot luck” strike, a small opening appeared above a large industrial complex that turned out to be the Mitsubishi arms manufacturing plant. Although the bomb itself was of a completely different design from Little Boy, the arming sequence was exactly the same. The bomb was released, and when the plane was far enough away, the 1.3GHz arming signal was transmitted, activating the firing electronics. At about 7,000 feet, the barometric safety switch kicked in, allowing the radar altimeter/trigger to function. At 1,650 feet, the radar altimeter closed a contactor inside the 8,000V power supply, feeding this voltage to the RC spark gap array. A couple of milliseconds later, all 32 spark gaps arced over within 10 nanoseconds of each other, sending 32 identical high voltage pulses to the array of exploding wire fuses. An instant later 32 identical convex flame fronts were shaped and merged into a single spherical imploding shock wave. The various metal layers were vaporised as the wave travelled through them, the surface area of the spherical shock wave decreasing by a factor of about 16 times, thus increasing the pressure by a similar amount. The plutonium pit 14  Silicon Chip Nagasaki suffered less damage than Hiroshima, due largely to the city’s topography. was compressed by a factor of about 2.5 times, a remarkable figure for a virtually solid ball of metal! When the shock wave reached the centre, the neutron initiator assembly was instantly converted to a series of high pressure jets of beryllium/polonium vapour which mixed with the vaporised plutonium to “kick-start” the chain reaction. Once the chain reaction was under way a massive burst of high-speed neutrons struck the surrounding cloud of uranium vapour, fissioning some of the U238 atoms and adding about 20% to the explosive yield. The yield of the explosion was estimated at about 21,000 tonnes, completely destroying the largely corrugated iron structures of Mitsubishi plant, with an initial death toll estimated at about 70,000. As was the case with Hiroshima, the death toll would have been a lot lower if people had retreated to the simple but effective bomb shelters dug into the hillsides. Because of the small number of aircraft involved, they probably assumed it was a reconnaissance mission. It may seem incredible now, to think that it took the Japanese over a week to surrender after the massive devastation of the initial Hiroshima blast, but the sad fact was that communications were so poor at the time that most of the populace (military included) simply had no idea that the attacks had taken place! All that they knew at the nearby army bases was that all communication (radio, telephone or tele- graph) from the bombed cities abruptly ceased, all at the same moment. Petrol was only available for military use, and civilian transport between cities was virtually non-existent. There are numerous accounts from Japanese Air Force pilots who were sent to investigate and who simply had no idea what had happened, since there was no sign of the cratering seen on conventional bombardments. The immediate post-war period When the war ended on August 15 1945 obviously there was an abrupt change of priorities. Now that the plants were up and running, operating costs fell dramatically and so production of weapons-grade uranium and plutonium continued, but few actual working bombs were constructed. By October 1945 there were 60 Fat Man assemblies (without plutonium pits) available but by July 1946 there were still only seven fully operational Fat Man type weapons in the US arsenal. Presumably the US government had more pressing things to spend its money on at the time and so the nuclear weapons program was put on the back burner. However in 1949 the detection of traces of radioactive fallout drifting across from Siberia indicated that the Soviet Union had successfully tested a nuclear weapon of its own. As it turned out, this was basically a direct copy of Fat Man, constructed using information supplied by spies operating inside Los Alamos. From that point the Arms Race began in earnest. SC siliconchip.com.au 10 SECONDS IN THE LIFE OF AN ATOMIC BOMB This amazing series of photographs is of the world’s first atomic bomb blast – at Alamagordo, New Mexico, USA on July 16, 1945. (Photos in this feature courtesy atomicarchive.com) 6: The mushroom cloud starts to form – two seconds after detonation. 1: The early fireball, taken just sixteen milliseconds after detonation. 7: And grows – three seconds after detonation. 2: Another nine milliseconds later, (at 0.025s) not much appears to have changed. 8: Again at four seconds after detonation. 3: Here’s the fireball at 53 milliseconds. 9: The head starts to take on the familiar mushroom form – seven seconds after detonation. 4: And at 62 milliseconds it’s growing . . . 10: The mushroom head fully formed ten seconds after detonation. 5: Less than one tenth of a second after detonation. 5: And again at 90 milliseconds. siliconchip.com.au siliconchip.com.au August ugust 2005  15 2005  15 A SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: dicksmith.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: dicksmith.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: dicksmith.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: dicksmith.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: dicksmith.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: dicksmith.com.au The Alfa Romeo 156 JTS (“Jet Thrust Stoichiometric”) engine uses Bosch direct injection. This gives the performance of a 2.3-litre unit, yet consumes 10% less fuel. The 2-litre engine has the same capacity as the Twin Spark engine it replaces, yet power is up from 114kW to 121kW and torque rises from 187Nm to 206Nm. [Alfa Romeo] By Julian Edgar Direct Petrol Injection Complex electronic control and direct fuel injection can provide fuel savings of up to 40%. The injectors work at much higher fuel pressures and must inject the fuel in extremely short times, within each cylinder’s intake or compression stroke. C ONVENTIONAL ELECTRONIC fuel-injected engines use injectors to squirt fuel into the intake ports. In a sequentially injected engine, each injector opens a short time before its associated intake valves, while in simultaneous-injected engines the injectors all open at the same time. In either case, the cloud of small fuel droplets is drawn into the engine only 22  Silicon Chip when the intake valves open. But a new breed of fuel-injected engines is now appearing. As the name suggests, Direct Petrol Injection uses injectors that add fuel directly to the combustion chamber. Like diesel engines, the air/fuel mixing occurs inside the combustion chamber, rather than in the inlet ports. Taking this approach gives far greater control over the combustion process, allowing for a variety of combustion operating modes, including those having ultra-lean air/fuel ratios. However, the degree of electronic control required to make smooth transitions from one combustion operating mode to another is complex and engine operating processes need to be monitored far more closely than is the case with conventional port fuel injection. Manufacturers are deciding that the added complexity is worth it – Mitsubishi has produced more than 700,000 direct-injected petrol engines (although none has been sold outside Japan) and BMW and Alfa Romeo are now selling cars with direct injected engines in Australia. Direct injected engines have even won major motor sports events, with siliconchip.com.au HIGH PRESSURE PUMP CARBON CANISTER FUEL RAIL CANISTER PURGE VALVE AIR-MASS METER WITH TEMPERATURE SENSOR ACCELERATOR PEDAL MODULE INJECTOR THROTTLE DEVICE (EGAS) IGNITION COIL PRESSURE CONTROL VALVE INTAKE MANIFOLD SENSOR PHASE SENSOR OXYGEN SENSOR (LSU) FUEL PRESSURE SENSOR KNOCK SENSOR PRE-CATALYST EGR VALVE EXHAUST GAS TEMP. SENSOR ELECTRONIC CONTROL UNIT NOX CATALYST DIAGNOSIS INTERFACE MALFUNCTION INDICATOR LAMP DELIVERY MODULE, INCLUDING LOW PRESSURE PUMP IMMOBILISER BOSCH COMPONENTS SPECIFICALLY FOR DE CAN BOSCH COMPONENTS OXYGEN SENSOR (LSF) Fig.1: the Bosch MED Motronic engine management system, which uses direct fuel injection, looks similar to conventional engine management. However, it uses a new Electronic Control Unit with many different functions, a second high pressure fuel pump, new design injectors, a fuel rail pressure sensor, and a second NOx catalyst. Some of the sensors are also used in unconventional ways. [Bosch] Audi’s direct-injected 455kW twin turbo 3.6-litre V8 triumphing at Le Mans. FUEL INJECTOR CROSS-SECTION 1 System mechanicals Fig.1 shows the layout of the Bosch direct injection system. Its mechanical elements differ from conventional port injection in several ways. First, the fuel supply system uses two fuel pumps – a conventional electrical fuel pressure pump (in the past dubbed a high-pressure pump but now referred to in this system as a low-pressure pump) and a mechanically driven high-pressure pump. The low-pressure pump works at pressures of 0.3-0.5MPa while the high-pressure pump boosts this very substantially to 5-12MPa. The high-pressure fuel is stored in the fuel rail that feeds the injectors. The fuel rail is made sufficiently large that pressure fluctuations within it are minimised as each injector opens. The pressure of the fuel in the injector supply rail is controlled by an siliconchip.com.au 2 3 The fuel injectors used for direct injection are subjected to enormous pressures. Minimum injector opening time is just 5ms and droplets are on average smaller than 20µm – just one-fifth the size of traditional injectors and one-third the diameter of a human hair. [Bosch] Fig.2 (right): cross-section of a direct petrol injection injector. (1) fuel inlet with strainer, (2) electrical connections, (3) spring, (4) solenoid, (5) injector housing, (6) nozzle needle with solenoid armature, (7) valve seat, (8) injector outlet passage. [Bosch] 4 5 6 7 8 August 2005  23 TORQUE (M) THROTTLE-VALVE POSITION/ EXCESS AIR FACTOR (l) Stratified Mode STRATIFIED MODE HOMOGENEOUS MODE Fig.3: although at least six different modes of combustion can occur in a direct injection engine, this diagram shows the two main modes. In Stratified Mode, the injector adds the fuel during the compression stroke, just before the spark plug fires. In the period between the injection finishing and the spark plug firing, the airflow movement within the combustion chamber transports the air/fuel mixture towards the spark plug. This results in a portion of relatively rich air/fuel mixture surrounding the spark plug electrode while the rest of the combustion chamber is relatively lean. In Homogenous Mode, injection starts on the intake stroke, so there is sufficient time for the air/fuel mixture to be distributed throughout the combustion chamber. Stratified Mode can result in air/fuel ratios as lean as an incredible 55:1. [Bosch] electronically-controlled bypass valve that can divert fuel from the highpressure pump outlet back to its inlet. The fuel bypass valve is varied in flow by being pulse-width modulated by the Electronic Control Unit (ECU). A fuel pressure sensor is used to monitor fuel rail pressure. a 1 0 Ivm b Ih tvm c 0 ton INJECTED FUEL QUANTITY NEEDLE LIFT CURRENT Imax 0 toff d INJECTION DURATION Fig.4: direct injection injectors use a peak/hold system of operating; (a) is the triggering signal from the ECU, (b) is the actual injector current, (c) injector needle lift, (d) injected fuel quantity. A booster capacitor is used to provide the high opening current. [Bosch] 24  Silicon Chip Second, compared with a conventional port fuel injection system, the fuel injectors must be capable of working with huge fuel pressures and also injecting large amounts of fuel in very short periods. Fig.2 shows a cross-sectional view of an injector. The reason for the much reduced time in which the injection can be completed is due to the fact that all the injection must at times occur within a portion of the induction stroke. Port fuel injectors have two complete rotations of the crankshaft in which to inject the fuel charge – at an engine speed of 6000 RPM, this corresponds to 20ms. However, in some modes, direct fuel injectors have only 5ms in which to inject the full-load fuel. The fuel requirements at idle can drop the opening time to just 0.4ms. Direct injection fuel droplets are on average smaller than 20µm – one-fifth the droplet size of traditional injectors and one-third the diameter of a human hair. Finally, the very lean air/fuel ratios at which direct injection systems can operate result in the production of large quantities of oxides of nitrogen (NOx). As a result, direct-injected cars require a primary catalytic converter fitted close to the engine and also a main catalytic converter – incorpo- Homogeneous Mode a b l=1 0 ACCELERATOR PEDAL POSITION Fig.5: during Stratified Charge Mode, the throttle is held wideopen, irrespective of the driver’s accelerator pedal input. In this mode, the air/fuel ratio (Bosch refer to an increased ‘excess air ratio’) is very lean when the torque request is low, with the air/fuel ratio gradually becoming richer as more torque is required. At a certain point, the engine changes to Homogenous Mode. With the change in modes, the throttle valve opening becomes related to the driver’s torque request and the air/fuel ratio holds a constant stoichiometric ratio (ie, 14.7:1 or Lambda = 1) across the rest of the engine load range. [Bosch] rating an NOx accumulator – fitted further downstream. Combustion modes The really radical nature of direct siliconchip.com.au OPERATING MODE COORDINATION Priority OPERATING MODE SWITCHING Function 1  Monitoring concept 2  Component protection 3  Limp-home functions 4   Adjustability of torque      and oxygen content limits 5   Catalytic converter heating 6  NOx accumulator      regeneration 7  SOx accumulator      regeneration 8  Starting/warming up 9   Diagnostic system manager 10   Operating mode map Required operating mode Changeover Function Control Functions • • • • Exhaust recirculation Fuel tank venting Swirl flap EGAS Fig.6: the direct injection system incorporates an operating-mode co-ordinator which uses a 10-stage priority system. Before the selected combustion mode starts to occur, control functions for exhaust-gas recirculation, fuel tank ventilation, charge-movement flap and electronic throttle settings are initiated as required. The system waits for acknowledgement that these actions have been carried out before altering fuel injection and ignition timing to provide the appropriate combustion mode. [Bosch] fuel injection can be seen when the different combustion modes are examined. There are at least six different ways in which combustion can take place. • Stratified Charge Mode: at low torque output up to about 3000 RPM, the engine is operated in Stratified Charge Mode. Here, the injector adds the fuel during the compression stroke, just before the spark plug fires. In the period between the injection finishing and the spark plug firing, the air-flow movement within the combustion chamber transports the air/fuel mixture into the vicinity of the spark plug. This results in a portion of relatively rich air/fuel mixture surrounding the spark plug electrode, while the rest of the combustion chamber is relatively lean. The gas filling the rest of the chamber Current operating mode For example: • Homogeneous mixture • Homogeneous lean mixture • Stratified mixture • Double injection often comprises recirculated exhaust gases, resulting in a reduced combustion temperature and decreased NOx emissions. In Bosch direct injection systems, the air/fuel ratio within the whole combustion chamber can be as lean as 22:1 - 44:1. Mitsubishi states that total combustion chamber air/fuel ratios of 35:1 - 55:1 can be used. Compare this with a conventional port fuel injected engine that seldom uses an air/fuel ratio leaner than 14.7:1. • Homogenous Mode: Homogenous Mode is used at high torque outputs and at high engine speeds. Injection Left & above: Audi has won Le Mans using direct-injected engines. The twinturbo 3.6-litre V8s developed 455kW, despite having to breathe through two 32.4mm restrictors and having the boost of the twin turbos limited to just under 10 psi. The adoption of direct petrol injection allowed the compression ratio to be lifted a point and gave a fuel reduction of 8-10%, a torque increase of 9% over a wide RPM range and quicker starting and better driveability. [Audi] siliconchip.com.au August 2005  25 CONTROL UNIT HIGH PRESSURE PUMP PRESSURE CONTROL VALVE PRESSURE SENSOR FUEL DISTRIBUTOR INJECTORS Fig.7: the high-pressure pump is driven directly from the engine and develops fuel pressures as high as 12MPa. This high pressure is regulated by a fuel pump bypass valve which is pulse width modulated by the Electronic Control Unit. The injectors are opened with a burst of high current from a capacitor that delivers up to 90V. A dedicated sensor monitors fuel rail pressure. [Bosch] The BMW 760 uses a direct injection 6-litre V12 developing 327kW and 600Nm. It complies with the EU4 emission standard in Europe and the LEV (Low Emission Vehicle) standard in the USA. Fuel consumption in the EU test cycle is 13.4 litres/100 km. The car accelerates from 0-100km/h in 5.5 seconds and continues on to 200km/h in 17 seconds. [BMW] 26  Silicon Chip starts on the intake stroke so there is sufficient time for the air/fuel mixture to be distributed throughout the combustion chamber. In this mode, Bosch systems use an air/fuel ratio of 14.7:1 (the same as with port fuel injection at light loads), while Mitsubishi use air/ fuel ratios from 13:1 – 24:1. • Homogenous Lean-Burn Mode: during the transition between Stratified and Homogenous Modes, the engine can be run with a homogeneously lean air/fuel ratio. • Homogenous Stratified Charge Mode: initially, this mode appears nonsensical – how can the combustion process be both homogenous and stratified? However, what occurs is not one but two injection cycles. The initial injection occurs during the intake stroke, giving plenty of time for the fuel to mix with the air throughout the combustion chamber. Then, during the compression stroke, a second amount of fuel is injected. This leads to the creation of a rich zone around the spark plug. The rich zone easily ignites, which in turn ignites the leaner air/fuel ratio within the remainder of the combustion chamber. Of the total fuel addition, approxisiliconchip.com.au mately 75% occurs during the first injection and 25% during the second. The Homogenous Stratified Charge Mode is used during the transition from Stratified Charge to Homogenous Modes. In addition there are at least two more modes: Homogenous Anti-Knock and Stratified Charge Cat-Heating. The first is used at full throttle and the second to rapidly heat the catalytic converter to operating temperature. A final mode – mentioned in only some of the literature – is Rich Homogenous Mode, which is used to regenerate the NOx accumulator in the main catalytic converter. (The NOx accumulator deposits oxides of nitrogen in the form of NHO3 nitrates. When the accumulator is regenerated, the nitrates – together with carbon monoxide – are reduced in the exhaust to nitrogen and oxygen.) Fig.3 shows the two primary combustion modes. Electronic control systems As indicated earlier, the injectors must be opened against very high fuel pressures. This is done using a peak/ hold technique, whereby the opening current is very high and the “hold” current much reduced. A dedicated triggering module is used to control the injectors, with a booster capacitor providing 50-90V to initially open the injector. Fig.4 shows this process. The sensing of the mass of cylinder charge is more complex on a directinjected engine than a conventional port-injected engine. This is because at times recirculated exhaust gas forms a major component of the total cylinder charge. As a result, two cylinder charge sensors are used. These comprise a conventional hot-film mass air-flow sensor (similar to a hot-wire air-flow meter) and a manifold pressure sensor (MAP sensor). The flow through the air-flow meter is used as an input into the calculation of the pressure within the intake manifold and this is then compared with the actual intake manifold pressure measured by the MAP sensor. The difference between the two indicates the mass flow of the recirculated exhaust gas. As with many conventional engine management systems, direct injection requires the use of an electronically controlled throttle. In conventional systems, the actual throttle opening siliconchip.com.au Fig.8: fuel is introduced directly into the combustion chamber by the highpressure injectors. Depending on the operating mode, the fuel can be added during the intake stroke, the compression stroke or during both the intake and compression strokes. [Bosch] Fig.9: there are two main approaches to aiming the fuel spray. In Wall Guided (left), the air movement within the combustion chamber guides the area of rich mixture in the direction of the spark plug. In Spray Guided (right), the fuel is injected directly into the vicinity of the spark plug. The latter approach gives improved emissions and fuel economy but thermally stresses the spark plug. [Bosch] more or less follows the driver’s accelerator pedal torque request. By contrast, in direct injected engines, the throttle is fully open for much of the time and varying the fuel delivery regulates engine torque output. Fig.5 shows how this occurs. During Stratified Charge Mode, the throttle is held wide-open, irrespective of the driver’s accelerator pedal input. When the torque request is low, the air/fuel ratio is very lean (Bosch refer to this as an increased ‘excess air ratio’), with the air/fuel ratio gradually becoming richer as more torque is required. At a certain point, which corresponds on an engine-specific basis to engine speed and the amount of torque required, the engine changes to Homogenous Mode. (For simplicity, the transitional Homogenous LeanBurn Mode is ignored in this diagram.) With the change in modes, the throttle valve opening becomes related to the driver’s torque request and the air/ fuel ratio holds a constant stoichioAugust 2005  27 losses – the engine is no longer trying to breathe through the restriction of the nearly-closed throttle. However, the downside of this is that the partial vacuum that’s normally available for the brake booster will be lacking. To overcome this problem, a vacuum switch or pressure sensor monitors brake booster vacuum and if it is necessary, the combustion mode is altered so that vacuum again becomes available. Increased efficiencies This photo shows the BMW V12 injectors and fuel rail. Fuel rail pressure varies from 30-100 Bar. The injection pumps are fitted above the outlet camshafts and are driven by an additional cam. [BMW] metric air/fuel ratio (that is, 14.7:1 or Lambda = 1) across the rest of the engine load range. The system incorporates an operating-mode co-ordinator which maps operating mode against engine speed and torque request. Fig.6 shows a schematic diagram of the functioning of this controller. As can be seen, a 10-stage priority allocation is used when determining the required operating mode. Before the selected combustion mode starts INJECTION to occur, control functions for exhaustgas recirculation, fuel tank ventilation, charge-movement flap (ie, port tumble valves or variable length intake manifold) and electronic throttle settings are initiated as required. The system waits for acknowledgement that these actions have been carried out before altering the fuel injection and ignition timing. The advantage of having the electronic throttle valve fully open at low loads is a huge reduction in pumping IGNITION COMBUSTION & ENGINE START As well as the huge reduction in pumping losses at low loads (due to the throttle being wide open), thermodynamic efficiencies are also increased during Stratified Charge Mode. This is because the rich cloud of combustible air/fuel mixture around the spark plug is thermally insulated by the layer of air and recirculated exhaust gas that surrounds it. Together with the much leaner air/fuel ratios than can be used in a conventional port injected engine, the result is a fuel efficiency improvement that can be up to 40% at idle. Mitsubishi state that at 35km/h, their direct injected engines use 35% less fuel than a comparably-sized conventional engine and that in the Japanese 10-15 Urban Driving Cycle (albeit a slow speed cycle), the direct-injected engine uses less fuel than even a comparable diesel engine. During homogenous mode operation, both the use of an air/fuel ratio that is never richer than 14.7:1 and the higher compression ratios normally associated with direct injection engines result in a fuel saving of about 5%. Conclusion Fig.10: another advantage of direct injection is that it is possible to start a hot engine without using the starter motor. This approach reduces startup hydrocarbon emissions, making it more attractive to use engines that automatically switch off if the car has been stationary for a period. [Bosch] 28  Silicon Chip Mitsubishi has been building direct injection petrol engines since 1996 but they have not been able to achieve worldwide success with their designs due, it is said, to the engines’ reliance on high-quality fuel. Now Bosch has developed technology which is allowing direct injected engines to be sold around the world. Combine direct injection technology with the hybrid cars being widely developed – plus perhaps downsized and turbocharged engines – and we’re certainly in for some interesting times ahead. But without the sophisticated electronics working behind the scenes, none of these engines would be posSC sible. siliconchip.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 MUDL ARK A 205 a u d i o s y s t e m s A 20-watt/channel class A2 triode amplifier Over the years, we have had lots of requests to design and publish a valve stereo amplifier. We have always resisted, partly because of the huge expense of a valve amplifier and the comparatively poor performance relative to well-designed solid-state amplifiers. But now we present a modern valve amplifier, designed by David Whitby. It uses quite a few novel techniques to keep the cost down while obtaining good performance. We’ll let David tell the story . . . Pt.1: By DAVID WHITBY V ALVE AMPLIFIERS are undergoing a resurgence today and those who would like to own one are often confused by all the technical and marketing jargon (eg, which type, brand, model, circuit, valve types, etc are best?). Many people are understandably put off by the fact that they may have to sell the family car to get the best model and the special speakers and super cables, etc that they are told you may need to make it all work properly. Take heart – the Mudlark A205 is a modern stylish design which works well with medium-efficiency speakers and comes as an affordably-priced kit or as a fully built-up amplifier. The Mudlark A205 comes in two parts, the main amplifier and the separate power supply box. The main chassis has four large output valves and two smaller driver valves. These are placed either side of a central rectangular housing which accommo30  Silicon Chip dates the filter and plate load chokes and output transformers. The chassis itself is a rugged aluminium extrusion while the front panel is made of polished black Bakelite with the labelling screen-printed in white for good legibility. The two vertical Perspex panels at the top of the amplifier are edge-lit with blue LEDs. Combined with the soft reddish glow from the filaments of the valves, this really adds to the appearance of the amplifier. The front panel is quite simple, with just a toggle switch for the power and two push-on/push-off switches for program selection and negative feedback on/off. Typical program sources which can be used include CD, tuner or tape deck. The overall styling is a combination of retro and modern which should have a very high PAF (partner acceptance factor). Why Mudlark? The Mudlark A205 is really the big brother of the Australianbuilt Mudlark A2-1 (pictured in this article), which was chosen as one of the highlights and also the “cutest thing” at the 2003 HiFi and AV Show in London. It has now been sold in Europe, the UK and the USA. The A2-1 is a small 2-channel valve circuit teamed with a solid-state subwoofer amplifier, while the A205 is a bigger full-range valve system. The A2 designation stands for class A2 operation. This refers to class-A which involves positive drive to the grids of the output valves on positive signal peaks for increased efficiency and higher power (sometimes called “extended” class-A in valve literature). Valve sound Simply put, a valve amplifier will have a particular tonal quality, desiliconchip.com.au The front panel controls are simple and include a power switch, a volume control, a negative feedback (in/out) switch and a source selector switch. pendent on the circuit configuration and valve types and even the brand of valve. This will be due to factors such as the relative levels of remnant second harmonic versus third harmonic components. Even very minute levels and differences can alter the perceived richness, sharpness, smoothness, etc. The generally lower damping factor of a valve amplifier (compared to the very high damping factor of solid-state amplifiers) also shifts the tonal spectrum, producing the “warmer” sound often attributed to valve amplifiers. All of this is hard to measure and quantify and is quite subjective but the bottom line is that valve enthusiasts find the sound attractive and enjoy experimenting with the circuits and loudspeaker combinations. The measured performance of valve amplifiers usually looks worse than for a solid-state amplifier but siliconchip.com.au The rear panel has RCA sockets for the source inputs plus the left & right channel speaker outputs. August 2005  31 Fig.1 (left): the Mudlark is a 3-stage single-ended amplifier operating in class-A2. Its two output valves are connected in parallel to give increased current drive, doubling the power available from a single valve. The circuit is unconventional because of the emitter follower used to drive the grids of the output valves and in the use of a choke as the plate load instead of a conventional output transformer. don’t let this put you off as the type of distortion and not just the total (THD) has a real influence on the final sound character. A valve stereo amplifier need not cost the earth, as you will see with this amplifier. The aim with the A205 was to get the looks and sound of a good valve amplifier with enough power to drive medium to high-sensitivity speakers. Design features Rather than going for a push-pull design, the chosen mode for the A205 is single ended triode. This early mode of valve amplifier operation is becoming quite common with audiophile designs today and although it is harder to get high power and low distortion than with a push-pull design, its particular sound character has found many followers. The residual distortion components of single-ended designs are mainly second harmonic (harmonious!) and a smaller amount of third harmonic, allowing operation with low or zero negative feedback. Most single-ended circuits of the 1940s to 1960s used pentode valves (eg, radios or “radiograms”), which had their own “tone” and often boomy bass – liked by many but hardly hifi. Very few people have experienced single-ended triode circuits with good transformers and high quality modern signal sources. I prefer triode operation for the output valves but have used a pentode in the output valve driver circuit in a configuration which has very low distortion. Modern rugged Russian valves from the 6L6 family have been chosen for the A205.These are beam power valves and are used as power triodes by connecting the screen grid to the plate (anode) in the circuit. Of all the reasonably priced power valves available 32  Silicon Chip siliconchip.com.au that I have tried, I find the modern 6L6 family of valves to be a good choice for sound, reliability and availability. Big power triodes like the 300B are good but they can be really expensive and I think most people will be happy with the 6L6 triode sound, their long life and low replacement cost. The actual types supplied with the kit are Russian-made Sovtek 6L6WXT or Electro-Harmonix 6L6GC/EH or the 5881. The latter is a ruggedised version of the 6L6 and it has a slightly different sound than the other valves. All these valves are made in the millions every year for famous name guitar and audio amplifiers around the world. The pre/driver valve is the 6GW8/ ECL86 or 14GW8/PCL86 triodepentode which combines one half of a 12AX7 type triode with a 9-watt power pentode. Both valve types are identical except for heater voltage and this is catered for by a link on the main PC board. The 6GW8 was used in huge numbers of sound systems in the 1960s, while the 14GW8/PCL86 was used as the sound section in millions of black and white TV sets in Europe, the UK and the USA. The 14GW8/PCL86 is available in large quantities and this is the one supplied in the kit. The 6GW8 is available as NOS (new old stock) and is more expensive. These valves were designed when miniature valve design was well advanced and are excellent as a combined pre/driver and output valve for small amplifiers and for driving larger power valves in higher-powered systems. In the A205, these valves are operated at far below their maximum ratings, resulting in good linearity and long life. Transformer solutions The power transformer in a typical valve amplifier is usually big and costly, with multiple windings for HT (high tension), heaters, bias, etc. By contrast, the Mudlark uses two standard toroidal transformers interconnected in a unique way to provide all the necessary voltages. This results in big cost savings without loss of performance. Just as expensive as the power transformer in a typical high performance valve amplifier is the output transformer, especially so for a single-ended design. The high plate current in the primary winding of single-ended siliconchip.com.au Fig.2: this set of plate current curves for the 6L6 family of valves shows the additional characteristic for positive grid voltage (red curve). transformers means a 20-watt unit can weigh several kilograms and cost $200+ each. To overcome this, we have used an output configuration that has become known as “parafeed”. This uses a relatively low-cost high impedance choke as the load for the plates of the output valves and a capacitor couples the audio signal to the primary of the output transformer. As a result, there is zero DC in the primary winding, so the output transformer can be much smaller and lower in cost without sacrificing quality. Circuit description Let’s have a look at the amplifier section first – see Fig.1. The audio signals are switched by a 2-way push-on/push-off switch and fed directly to a 50kW dual-ganged (log) potentiometer. From there, the signal is fed via a 22kW 1W resistor to the grid of the triode section of valve V1 (14GW8, etc). The output signal The Mudlark A205 is the big brother of the Mudlark A2-1, a small 2-channel valve amplifier teamed with a solidstate sub-woofer amplifier. The “A2” designation stands for class-A2 operation, which involves positive drive to the grids of the output valves on positive signal peaks for increased efficiency and higher power. August 2005  33 The power supply box houses two large toroid transformers, which are connected back to back. Their outputs are fed to an octal socket and connected to the amplifier board via a 1.5-metre cable. from the plate of this valve is coupled via a 22nF 400V polyester capacitor and an attenuator consisting of 470kW and 220kW resistors to the grid of the pentode section. The pentode section is supplied with a screened grid voltage of 120V. This is below the lowest voltage swing of the anode and under these conditions, the driver stage contributes very little distortion to the amplifier. The output impedance of the pentode driver is 13.5kW, as set by the two 27kW 3W paralleled plate resistors. Fig.3: want to bypass that dreadful transistor? Here’s how to do it. The result will be a small reduction in maximum power output. 34  Silicon Chip This is suitable to drive the grids of the 6L6 valves directly (class-A) but improved performance (class-A2) is provided by the use of a BF469 transistor as an emitter follower. This is important because, depending on the signal amplitude, the grid is driven positive and does draw grid current but only on the highest positive peaks. Incidentally, this is a no-no for some valves but the 6L6 is characterised for positive grid current, as can be seen in Fig.2. In practice, with average listening levels and reasonably efficient speakers, class A2 is seldom reached but is available if needed. It allows higher peak power for more headroom, which also translates into higher RMS power if measured with a sinewave input signal. Two valves are used in the output stage. They are connected in parallel and have a common 56W cathode resistor, bypassed by a 220mF capacitor. The plate current for the two valves passes through a 9H (nine Henry) choke – essentially three standard compact fluorescent ballasts connected in series – and this provides a high AC impedance but low DC resistance to supply the HT to the plates. The output signal is then coupled to the primary of the output transformer via a 10mF 400V polypropylene capacitor. As result, since there is no DC in the primary of the output transformer, it can be a small and relatively lowcost hifi 100V line transformer. This is my version of the “parafeed” mode referred to earlier and it gives substantial cost reductions while giving good performance. The bias on the output valves is a mixture of negative grid bias, provided via the emitter follower, and cathode bias provided by the common 56W cathode resistor. The latter provides a degree of automatic adjustment of the plate current to compensate for changes in plate voltage and valve aging. For those not familiar with valve operation, they can be likened to Nchannel FETs, in which the operating current is set by the negative gatesource voltage. In a valve, the plate current is set by the grid-cathode voltage, called the “bias”. By the way, for those people who don’t like the idea of a transistor being used in a valve amplifier, it is possible to keep the circuit “pure” siliconchip.com.au siliconchip.com.au August 2005  35 Fig.4: this is the circuit for the power supply. It incorporates a delay circuit to prevent HT being applied to the output valve plates until their cathodes are at the correct operating temperature. Here’s a sneak preview of the PC board inside the amplifier case. We’ll show you how to build it next month. and bypass the transistor, as shown in Fig.3. This does cause a reduction in maximum power of less than 3dB. This is noticeable only at very high output but otherwise the character of the amplifier is not changed. While we’re on the subject of bias, the pentode section of the first stage operates with cathode bias, provided by the 220W 1W resistor. This is not bypassed by a capacitor, so we have cathode current feedback, otherwise known as “cathode degeneration”. This serves to lower the stage gain and slightly improve linearity. The triode section of the first stage also employs cathode bias. However, in this case, the 680W resistor is bypassed by the 220mF and 470nF capacitors, so the full gain of the triode is obtained, although to set the required gain and reduce noise, some of it is lost in the following resistive attenuator. Note that the 680W resistor also carries the cathode current from the triode section in the other channel (V4). 36  Silicon Chip The triode grid also has a small degree of negative feedback applied from the secondary of the output transformer, via a 220kW resistor to the junction of the 100kW and 10kW grid resistors. Switch S2, on the front panel, allows the negative feedback to be cancelled, which gives a gain increase of about +6dB and a corresponding increase in harmonic distortion. The switch is included for those people who may prefer to use the amplifier without any overall feedback. The overall gain of the driver is set at 20 and the drive voltage capability is in excess of 120V peak-peak. Two output valves were used in parallel to get the required power. With both channels operating, power output is 17-20 watts per channel (3440 watts in total) over a 220-245VAC mains voltage range. Power supply Most of the power supply is housed in or above the main chassis while the two toroidal transformers are mounted in a separate box. The power supply circuit is shown in Fig.4. The power supply looks fairly complicated but that is mainly as a result of the delay circuit which stops the high voltage (HT) being applied to the valves before their cathodes have been heated by the filament current. Without this delay, the HT could initially rise to quite high values, which could damage some of the filter capacitors. It could also cause what is known as “cathode stripping” when higher than normal HT voltages are applied to the plate before the correct cathode temperature is reached and material is stripped from the cathode, thereby reducing valve life. The extra complication is well worth it for extended valve and component life. In essence, the two 160VA toroidal transformers, T1 & T2, are connected back-to-back. Transformer T1 runs conventionally, supplying 25VAC to the 30VAC centre-tapped secondsiliconchip.com.au ary winding of transformer T2. With 25VAC applied in this way and coupling losses due to reverse operation, T2 produces 150VAC at full load on what would normally be its primary winding. This feeds a voltage doubler rectifier circuit consisting of diodes D1 & D2 and four 270mF capacitors. The DC from the voltage doubler is further smoothed by the LC filters consisting of 3H (three Henry) chokes and 100mF 400V capacitors. The resulting output is about 400V DC. Incidentally, the 3H choke used here is the same compact ballast choke as used for the valve plate chokes. These chokes are of extremely high quality and low noise. Better still, they are Australian-made and are a bargain when compared to hard-to-get and costly EI lamination chokes. If you have looked closely at the valve circuit of Fig.1, you will have noted that the supply voltages to the plate chokes for the output valves are + 480V (nominal). How so? The extra 100V comes from a diode pump involving diodes D4, D5, D6 & D7 and two 1000mF 63V capacitors. The 100V DC is stored in four 1000mF 63V capacitors which are connected as two series-connected pairs, to obtain sufficient voltage rating. This diode pump circuit also supplies +60V, from the junction of diodes D5 & D6 and the associated 1000mF capacitor. The +60V is the positive supply rail for the emitter follower Q1 (and Q2 in the other channel). Another diode pump circuit, involving diodes D8-D11, provides the -27V and -120V rails for the emitter followers (Q1 & Q2). HT delay & protection circuit As noted previously, the circuit provides a delay so that HT is not applied to the plates of the output valves until their cathodes have been warmed up. This delay is provided by a 555 timer IC, connected as a conventional monostable to drive relay 1. This switches one of the 150VAC secondary feed wires from transformer T2 and thus stops the abovementioned voltage doubler rectifier from working. Transistor Q3 monitors the AC current drawn by the filaments (heaters) of the four output valves, which are connected in series across the 25VAC siliconchip.com.au Although not visible here, the two Perspex panels at the front are edge-lit with blue LEDs for a really fancy appearance. supply from the secondary winding of transformer T1. If one of the valves is removed from its socket, no filament current can flow and so Q3 turns off. This removes the negative supply to the 555 and the relay, which then switches off the HT rail. Note that there is a link provision in the circuit so that the filaments (heaters) of the driver stages can be 25VAC for two 14GW8 filaments in series or 12.5VAC if two 6GW8s are used. Normally, 14GW8 valves will be supplied in the kits. All of the DC and output chokes and the output transformers are mounted under the long central cover on top of the chassis. They are connected to the main PC board by a short cable and octal plug which makes dismantling and removing the board relatively easy. Next month’s article will provide the full assembly details and the perSC formance measurements. Where To Buy A Kit The price for the full kit (including finished metalwork, panels and all components) is $870.00 (including GST) or with a fully assembled and tested PC board $970.00 (including GST). All metalwork and panels in the kit are fully finished and no drilling, cutting or punching is required. Kits will be available from September 2005 and we strongly recommend that you order before mid-August to receive your kit in the September shipment. The A205 will also be available fully built and tested. Please contact Gless Audio for prices. Valves and other components will also be available. Kits and fully built amplifiers will be available from: Gless Audio, 26 Park St, Seaford, Vic 3198. Phone (03) 9776 8703; email sales<at>glessaudio.com August 2005  37 Flexitimer An Easy-To-Program Digital Timer This new multi-purpose timer is much more flexible than previous designs. You can program it for a single time period ranging from one second to 99 minutes and 59 seconds, or a sequence of two such (independently programmed) time periods, or up to 99 cycles of one or two time periods. It’s also easy to program – just like a microwave oven. By JIM ROWE E LECTRONIC TIMERS have always been popular. In fact, there are so many applications for this kind of project that it’s only scratching the surface to mention the following: parking meter reminders, EPROM erasure timing, darkroom printer/ enlarger timing, PC board etch timing, battery charge timing, industrial process timing, chess and other board game timing, debate timing and even kitchen timing. 38  Silicon Chip If you want to make a timer with the widest range of applications, it needs to have at least two independently adjustable or “programmable” timing periods. Ideally, it also needs to be flexible in terms of the number of time periods and/or time period sequences (or cycles) that can be programmed. Some applications need just a single time period, timed in “single shot” fashion, while others need a single sequence of one time period followed by a second (and probably different) time period. Still other applications may need a sequence of two time periods repeated many times, say for a total of 20 cycles. Previous timer designs published in SILICON CHIP and other magazines have provided most of these features but at the cost of operating and programming complexity. This made them a bit daunting to use and limited their popularity as a result. By contrast, this new timer is programmed in exactly the same intuitive fashion as a microwave oven. First, it has tens and units buttons to allow you to key in the exact number of minutes and seconds for the time period(s) you want and also the number of timing cycles you want. There are also buttons to start and stop the timer manually and to save its settings for the next time it’s used and so on. We’ve dubbed this new unit the “Programmable Flexitimer”, because it’s designed to provide the same order of flexibility as the Flexitimer siliconchip.com.au siliconchip.com.au August 2005  39 Fig.1: the circuit is based on a programmed PIC16F84A-04 microcontroller and this drives an LCD module, two relay driver circuits (one for Time A and one for Time B) and a piezo buzzer circuit. It’s programmed using 10 pushbutton switches. Resistor RBL sets the current through the backlighting LEDs on the Altronics and DSE modules (see text). Par t s Lis t 1 Jiffy box, 158 x 95 x 58mm 4 6mm-long untapped spacers 5 12mm-long untapped spacers 1 M3 x 6mm machine screw 4 M3 x 12mm machine screws, csk head 5 M3 x 20mm machine screws, csk head 11 M3 nuts and star lockwashers 1 75mm length of 16-way IDC ribbon cable 2 16-way IDC ribbon connectors Main Board 1 PC board, code 04108051, 141 x 83mm 1 12V piezo buzzer (PB1) 1 4MHz quartz crystal (X1) 2 12V SPDT relays to suit 1 PC-mount 2.5mm DC input connector (CON1) 2 PC-mount 3-way terminal blocks (CON2, CON3) 1 PC-mount 16-way DIL pin header (CON4) 1 18-pin DIL IC socket 1 TO-220 heatsink, 6021 type, 30 x 25 x 13mm Semiconductors 1 PIC16F84A (IC1) programmed with PICTIME2.HEX firmware 1 7805 5V regulator (REG1) 2 2N7000 MOSFETs (Q1,Q2) 1 PN100 NPN transistor (Q3) 3 1N4004 1A diode (D1,D2,D3) Capacitors 1 2200mF 25V RB electrolytic projects described by Rob Evans in “Electronics Australia” back in the early 1990s. However, this new design is based around a programmed PIC microcontroller chip and, as a result, is much easier to “drive” than those earlier timers. Main features Here’s a quick summary of its capabilities. First, it provides either one or two programmable time periods (Time A and Time B), each of which can be set independently to any time between one second and 99 minutes 59 seconds – with a resolution of one second. Second, you can set it for just a single Time A period, or a single 40  Silicon Chip 1 100mF 16V RB electrolytic 3 100nF multilayer monolithic 2 33pF disc ceramic Resistors (0.25W 1%) 1 100kW 1 4.7kW 4 22kW 2 10W 2 10kW Display Board 1 PC board, code 04108052/3/4 to suit DSE, Jaycar or Altronics LCD, 132 x 84mm – see text 1 LCD module, 2 lines x 16 chars (see text) 1 14-way or 16-way length of SIL or DIL pin header strip, to suit LCD module used 10 PC-mount SPST pushbutton switches (S1-S10) 1 90° PC-mount 16-way DIL header (CON5) 4 M2.5 x 10mm machine screws, round head 4 M2.5 hex nuts and lockwashers 8 M2.5 flat washers 4 M3 hex nuts (used as spacers) Capacitors 1 10mF 16V RB electrolytic Resistors (0.25W, 1%) 1 68kW 1 12W to suit DSE Z-4172 LCD module (RBL) – see text 1 18W to suit Altronics Z-7011 LCD module (RBL) – see text 1 10kW mini horizontal trimpot (VR1) (Time A + Time B) sequence, or for multiple Time A or (Time A + Time B) cycles. In fact, there can be anything from 2-99 such cycles. Third, the timer has two internal relays, one of which is activated during the Time A period and the other during Time B. Both relays have a set of mains-rated single pole, double throw (SPDT) contacts, so they can be used either separately or together to switch a wide variety of loads. Finally, the unit operates from 12V DC, which can come from either a battery or a plugpack power supply. Programming As mentioned earlier, the time periods and cycles are programmed very easily using four pushbuttons: one each for tens of minutes, units of minutes, tens of seconds and units of seconds. The “10-minute” and “1-minute” buttons are also used to program the desired number of cycles, when you want more than a single cycle (the default). Three further buttons allow you to set the current input as either Time A or Time B, or to set the number of cycles. Another button (Enter) is then used to save all of the current time and cycle settings in the PIC’s non-volatile memory, so that it “remembers” them when it’s powered up next time. Finally, the Start and Stop buttons do exactly as their names suggest – ie, either start the timer operating or manually stop it if the need arises. All of the timer settings and operations are displayed on a small 2-line x 16-character LCD module. This makes it really easy to operate. How it works Fig.1 shows the circuit details of the Programmable Flexitimer. All of the real work is done by microcontroller IC1, a PIC16F84A which is programmed with a dedicated firmware program called PICTIMER.HEX. In operation, the microcontroller runs from a 4MHz crystal clock and does all of the timing by counting clock cycles – using a combination of both hardware and software counting. This gives a timing accuracy of better than ±0.02%. The 10 buttons used to program the various settings and commands into the PIC microcontroller are connected in a 3 x 4 matrix configuration. As shown, the three rows are connected to the three most significant bits of IC1’s Port B (RB7, RB6 & RB5), while the four columns go to the four least significant bits of this port (RB3, RB2, RB1 & RB0). This allows the microcontroller to scan all the keys very efficiently and respond quickly when they are pressed. The LCD module is directly driven by the microcontroller. It’s connected to the four most significant bit Port B lines (RB7-RB4) and to the two most significant bit Port A lines (RA4 and RA3). The two Port A lines are used to enable the LCD controller input for writing (EN) and to select either its siliconchip.com.au Fig.2: install the parts on the main PC board as shown here. Take care to ensure all polarised parts are correctly orientated and note that connector CON4 goes in with its keyway slot to the left. A small heatsink is fitted to REG1, so that it can handle the current requirements of backlit LCDs. data or address/instruction registers (RS). By contrast, the four Port B lines are used as a data bus to feed display character codes and position addresses to the LCD controller, along with various other function commands. Trimpot VR1 is used to adjust the display contrast. It does this by varying the DC voltage applied to pin 3 of the LCD module. The two least significant bit Port siliconchip.com.au A lines (RA0 & RA1) function as outputs and are used to drive Mosfets Q1 & Q2, which then control the two relays. When the unit is running, the microcontroller turns on Relay 1 (via Q1) during Time A and Relay 2 (via Q2) during Time B. The remaining Port A output line (RA2) is used to control Q3, which in turn controls piezo buzzer PB1. In operation, output RA2 briefly goes high and turns on Q3 to produce a short “beep” at the end of the programmed time period(s) or cycles. Power supply Power for the unit comes from a 12V DC plugpack (or battery), with diode D1 providing reverse polarity protection. This then feeds regulator REG1 which provides a +5V rail to power IC1 and the LCD module. The relays and August 2005  41 Fig.3: the display board layout for the Altronics LCD modules. Install resistor RBL (18W) only if you are using a backlit display (Cat. Z-7001) & don’t forget the backlight connections. Fig.4: follow this display board layout if you are using a DSE LCD module. Again, resistor RBL (12W) is installed only for the backlit display (Cat. Z-4172). the buzzer (PB1) are powered directly from the +12V rail after D1. Construction Construction of the Programmable Flexitimer is easy, with all parts mounted on two PC boards – a main board coded 04108051 (141 x 83mm) and a separate display board (132 x 84mm). The latter carries the LCD and the pushbutton switches, plus a few 42  Silicon Chip other minor parts. These boards fit inside a standard UB1 Jiffy box (158 x 95 x 58mm) and are interconnected by a short 16-way ribbon cable fitted with 16-way IDC connectors at each end. The connections to the timer relay contacts are made via screw terminal blocks located at one end of the main board. Note that there are actually three different versions of the display board, to suit the three different LCD modules currently available on the Australian market. One version (code 04108052) suits the Z-4170/2 module from Dick Smith Electronics; a second version (code 04108053) suits the QP-5515/6 module from Jaycar Electronics; and the third version (code 04108054) suits the Z-7000A/Z-7011 module available from Altronics Distributors. Fig.2 shows the assembly details for siliconchip.com.au Fig.5: the Jaycar LCD modules have only 14 pins and don’t require an external resistor to set the current through the backlight LEDs. This completed display board uses the DSE Z-4170 LCD module – ie, no backlighting, so RBL is left out. Take care to ensure that the flat side of each switch goes to the left. the main board. Start by fitting the DC input connector CON1 (may need to elongate the PC board holes slightly with a needle file before the connector lugs will pass through), then fit the two screw terminal blocks (CON2 & CON3). Note that the latter must be fitted with their wire entry sides facing the edge of the board. Next, fit the 16-way DIL pin header CON4, making sure its locating spigot siliconchip.com.au slot goes towards the lefthand end of the board. That done, fit the two wire links, followed by the resistors and the three diodes (D1-D3). Make sure that the diodes are correctly oriented. The 4MHz crystal (X1), regulator REG1 and transistors Q1, Q2 & Q3 are next in line. Take care with the orientation of REG1 and the transistors and be sure to use the correct transistor type at each location. Regulator REG1 is installed by first bending its pins downwards through 90° about 6mm from its body. It’s then fitted to the PC board along with its heatsink and secured using an M3 x 6mm machine screw and nut, before soldering its leads. Smear its metal tab with heatsink compound before mounting it, to ensure good heat transfer. The next step is to fit an 18-pin sockAugust 2005  43 Fig.6: here are the drilling an cutting details for the base of the case and for the lid. They are reproduced actual size, so that you can use photocopies as drilling templates. 44  Silicon Chip siliconchip.com.au et for IC1 – it goes in with the “notch” end facing the adjacent edge of the board (see Fig.2). Follow this with the two relays and the piezo buzzer (PB1). There are two buzzer types commonly available and the PC board caters for both. It’s just a matter of fastening the supplied unit in position using two M3 x 12mm machine screws and nuts and soldering its leads to the board (red to “+”, black to “-”). In either case, the buzzer’s connection wires can be cut fairly short before soldering, to keep the assembly neat and tidy. The small non-polarised capacitors can now be fitted, followed by the two larger polarised electrolytics. Be sure to install the electrolytics with the positive leads oriented as shown. The main board assembly can now be completed by plugging the programmed PIC16F84A chip into its socket. It must be installed with its notched end towards the bottom edge of the board, as shown in Fig.2 By the way, if you’re building the timer from a kit, the PIC will be supplied pre-programmed. However if you’re building the timer from scratch, you’ll need to program the chip yourself (or have someone do it for you) before it’s plugged into the socket. The PICTIMER.HEX program file will be available as a free download from the SILICON CHIP website at www.siliconchip.com.au Display board assembly Before installing any parts on this board, make sure it suits the particular LCD module you’re using. Of course, if you’ve bought a kit, then you won’t have any worries on this score. Figs.3, 4 & 5 shows the parts layouts for the Altronics, Dick Smith Electronics and Jaycar versions respectively. Begin by installing the wire links and the 68kW resistor, then fit the 16- Fig.7: here are the drilling details for the end of the case, again reproduced actual size. way 90° DIL pin header. Follow these with trimpot VR1 and the 10 pushbutton switches. Note that the latter are all mounted with their “flat” side facing towards the left. The 10mF electrolytic capacitor is next on the list. As shown in one of the photos, it should be mounted “leaning over” to the left by a small amount, to reduce its effective height to below 10mm (to ensure it later clears the back of front panel). Take care with its orientation. The next step is to fit the header strip for the LCD module. This is a 16-way SIL strip for the DSE module, a 7 x 2-way DIL strip for the Jaycar module or a 14-way SIL strip for the Altronics module. In each case, push the shorter ends of the pins through the board from above and solder them carefully to the pads underneath. Basically, there are six different LCD modules that can be used with this unit – three with backlighting and three without. The three modules with backlighting are the Altronics Z-7011, DSE Z-4172 and the Jaycar QP-5516. The corresponding versions without backlighting are Altronics Z-7000A, the DSE Z-4170 and the Jaycar QP5515. Note that the Jaycar modules have 14 pins, while both the Altronics and DSE modules have 16 pins. Installing the LCD module is easy – it slips down over the header pins and is secured using four M2.5 x 10mm screws, lockwashers and nuts. In addition, an M3 nut and two M2.5 flat washers are used to form a 3mm3.5mm spacer between the module and the board at each mounting screw point. Alternatively, you can use two M3 “half nuts” to make the spacer at each point. Once the module is in position, it’s simply a matter of soldering its connection pads to the header pins. The display board will now be complete, except for resistor RBL which sets the current for the backlighting LEDs. This is fitted only if you’re using an LCD module with backlighting but is not required for the Jaycar LCD, since the resistor is part of the module. Table 1: Resistor Colour Codes o o o o o o o o o siliconchip.com.au No.   1   1   4   2   1   1   1   2 Value 100kW 68kW 22kW 10kW 4.7kW 18W 12W 10W 4-Band Code (1%) brown black yellow brown blue grey orange brown red red orange brown brown black orange brown yellow violet red brown brown grey black brown brown red black brown brown black black brown 5-Band Code (1%) brown black black orange brown blue grey black red brown red red black red brown brown black black red brown yellow violet black brown brown brown grey black gold brown brown red black gold brown brown black black gold brown August 2005  45 The main board in this prototype unit used a 78L05 regulator. It was later modified to accept a 7805 regulator (with heatsink), so that backlit LCDs could be used. Note that for the Altronics module, you’ll also need to make the “A” and “K” connections for the backlighting power (at right). Once the assembly is completed, adjust contrast trimpot VR1 with a small screwdriver to about 10° back from fully clockwise. This will ensure you get some kind of display when the timer and module are first powered up. The control can be “fine tuned” for best contrast later, via the small hole in the front panel. The next step is to make the short ribbon cable that’s used to link the two boards. This is formed from a 75mm-length of 16-way IDC ribbon, with a matching IDC connector at each end – see Fig.8. The connectors fit the opposite way around at each end, so that the cable can link the two boards without having to be twisted. Preparing the box If you’re building the timer from a kit, the box will probably be supplied with a silk screened front panel and with all holes pre-drilled and cut. However if you’re building from scratch, you’ll need to drill the box yourself. Figs.6 & 7 show the drilling and cut- ting diagrams for both the box and its lid. These are reproduced actual size, so you can directly use photocopies as drilling templates. Make sure you countersink the 3.5mm holes in the bottom of the box and also those in the lid. This can be done with a 7mm or larger twist drill if you don’t have a countersink bit. Also, make sure that you cut the access holes for the timer’s DC input connector and terminal blocks at the right-hand end of the box – see Fig.7. Next, the front panel artwork can be attached to the lid. That done, you can cut the various holes in the label using a sharp hobby knife. Final assembly The main board mounts on the bottom of the box on four 6mm-long untapped spacers and is secured using four M3 x 12mm countersink-head screws and nuts (it only fits one way, due to the asymmetrical mounting screw positions). By contrast, the display board is mounted on the box lid and is secured on 12mm-long untapped spacers using five M3 x 20mm countersink-head machine screws, star lockwashers and nuts. With some LCD modules, Fig.8: follow this diagram to fit the headers to the short ribbon cable that links the two PC boards together. 46  Silicon Chip you may also need M3 flat washers to augment each of the spacers, to make sure there is enough clearance. Your timer can now be completed by fitting the ribbon cable between the two boards and securing the case lid. Using the timer When you first connect the timer to 12V DC power, it initially displays “Silicon Chip FlexiTimer3” on the LCD panel. This message then disappears after a few seconds and is replaced with a “screen” giving you the timer’s current settings – plus “Stop” at lower right to show that it’s not running. When the timer is powered up for the very first time, its initial settings are these defaults: Time A programmed to 10 seconds, Time B not programmed at all (and not even displayed), and the Cycles set to 1 (for a single timing sequence). But if you program it with other settings and save them, these settings will appear when the timer is next powered up. Changing the settings for Time A or Time B is done using the four uppermost buttons on the left – marked “10 MIN”, “1 MIN”, “10 SEC” and “1 SEC”. Pressing any of these buttons causes the timer to change into “Input” mode, to allow you to key in any desired time setting from 00 minutes and 1 second up to 99 minutes and 59 seconds. If you press any button too many times, just keep pressing it until the digit concerned reaches the maximum and then returns to 0, after which you can program the value you wanted. When you have entered the time value you want, the timer can be siliconchip.com.au Fig.9: this artwork can be photocopied onto an A4 label sheet, which can then be affixed to the lid after peeling off its backing. Clear “Contact” adhesive film can then be fitted over the top, to protect it from dirt and damage. directed to make this the setting for either Time A or Time B, simply by pressing either the “Time A” or “Time B” button. It’s as easy as that. Changing the Cycles setting is just as easy. In this case, you use only the “10 MIN” and “1 MIN” buttons to enter the number of cycles (from 1-99), and then press the “SET CYCLES” button. Once the settings for Time A, Time B (optionally) and Cycles have been entered, the timer can be started simply by pressing (you guessed it) the “START” button. You’ll then see it counting down on the LCD panel, where its status is also shown continuously – ie, whether it’s in Time A or Time B and the current cycle. When it reaches the end, it will give a short beep from the piezo buzzer and display “Stop” again on the LCD panel (at lower right). This will also happen if you press the “STOP” button, to stop the unit before the end of the programmed time settings. To save the current settings in memory for use next time it’s powered up, just press the “ENTER (SAVE)” button when the timer is stopped. As soon as the settings have been saved, the message “Settings Saved” will be displayed for a few seconds, to confirm that it has been done. To program Time B as well as Time siliconchip.com.au A, all you need do is enter its time setting and then press the “TIME B” button. Time B will then be enabled and its setting displayed after Time A. On the other hand, if you have Time B already programmed and you want to disable it again, simply enter a zero time value (ie, 00:00) and again press the “TIME B” button. The timer will recognise the zero time setting and Time B will be disabled and disappear from the display. You can use the timer’s relay contact terminals to allow it to control all manner of things. All you need to know is that when the timer is running the contacts of Relay 1 are activated during Time A, while those of Relay 2 are activated during Time B. So by connecting to these terminals, you can arrange for the timer to turn things on or off during Time A and/or Time B. Finally, note that this project should be used to control low voltage equipment only (up to about 50V). Do not use it to directly switch mains voltages. If you do want to switch mains voltages, we suggest that you use this unit to trigger an external relay which then does the switching. Make sure that this external relay and any mains wiring that’s run to it is properly anchored and isolated. However, don’t attempt this unless Specifications • • • • Two independent timing periods: Time A and Time B Time A and Time B periods can be set from 00min-01sec to 99min-59sec 1-99 timing cycles or continuous cycling – see below Relay outputs for switching external devices Continuous Cycling A late software modification to this unit involved adding a continuous cycling mode. This mode is set simply by entering zero (00) as the setting for “Cycles”. The second line of the display shows “Cont” when the timer is in this mode. It can be returned to finite multiple cycle mode simply by setting the number of “Cycles” to any allowed non-zero value – ie, 1-99. you know what you are doing and are completely familiar with mains wiring SC practices and techniques. August 2005  47 SERVICEMAN'S LOG Tracking down a really rotten fault Most TV servicing is fairly routine but every so often you come across a really rotten fault. Still, I guess I’d get rather bored if it was all too easy. Mrs Roseberry wanted a technician to call out and fix her 2000 Panasonic TC-68PS10 (MX8A chassis) because it had a white line across the screen and no picture. Obviously, the vertical timebase had failed and I was hoping it was just R519, the 1W feed resistor for the 28V rail that supplies IC451 (LA78045) and which is sometimes dry-jointed. Well, I was right about this and it was quickly fixed, even though access to the board is rather difficult. Unfortunately, this revealed a second problem – the screen was now fully scanned but the bottom had foldover and the top was stretched. I did manage to check all the voltages on the seven IC pins (with difficulty because of the annoying plastic support bar that crosses this IC underneath) but they were all within Items Covered This Month • • • • • • • • Panasonic TC-68PS10 TV set (MX8A chassis) Sony FD Series Trinitron KV32FX65E TV set (AE-5 chassis SCC-Q14K-A) Panasonic TC-21PM50A TV set (GP3 chassis) JVC AV-28STEKGR TV set (JK chassis) Grundig Xentia 72 Flat MF 72-490/8 Dolby (CUC1832 chassis) Grundig Elegance 82 Flat MFW-82-3110 MV/Dolby (CUC 1935 chassis) Sony KV-ES29M31/SAU3 TV set (AG3 chassis SCC-P92A-A) Naim CD3 compact disc player 48  Silicon Chip tolerance of the voltages specified in the MX8 service manual. In the end, there was nothing I could do but transport this heavy flat-screen set back to the workshop. Once there, I removed the plastic support and began checking everything out, first with an ohmmeter and then with the CRO. The only waveform that looked slightly out was the output from pin 5 of IC451 where the ramp ended abruptly and flattened out. All the other waveforms looked OK. I replaced the IC and all the electrolytic capacitors around it one by one but nothing was making any difference. Next, I connected the chassis to another set’s yoke (and vice versa) and this showed that the deflection yoke was OK. I then checked the 50/60Hz switching transistor (Q465) which was also OK and even swapped EEPROM IC1102 in case the software geometry controls were scrambled. Again, I drew a blank. Grasping at straws, I next did the modification for resistor R404 (it was 9.53kW and is now 13kW to fix top lefthand line tearing). That done, I checked all the resistors on the top of the board and the surface-mounted ones underneath. I then tried heating and freezing the board, as well as vibration and twisting, but nothing was giving up any clues. Basically, what I had was a vertical output IC with all the correct voltages and the correct waveforms going into it but with one distorted waveform coming out. I checked and tried disconnecting the feedback loops but this one really it had me stumped. And on top of that, Mrs Roseberry was hassling me for a quote and ETA. It was time for some lateral thinking. Even though I had a perfect waveform going into pin 1 of IC451, I next turned my attention to IC401 (AN54415-E1), which is a 28-pin surface-mounted timebase control IC. I checked the 5V and 12V rails to pins 4, 15 & 25 and checked to ensure there was no significant ripple on these rails. I even replaced this IC (the electrolytics had already been changed) but it still made no difference. So what else could I possibly do? The check service menus provided no clue and all worked as they were supposed to. It really was time to think outside the square and perform some unorthodox tests. After first making sure there were no high-voltage rails nearby, I ran my fingers all over the vertical timebase circuitry with the set on to see if there was any effect. Well, the leakage due to my fingers gave a variety of distortion effects but nothing really significant until I got near pins 22-28 of IC401. By wetting my fingers slightly and rubbing them across these pins, I could almost correct the fault. However, because the IC was so small (and my fingers are relatively large), I couldn’t initially identify which pins were the ones I was affecting. A glance at the circuit showed that pins 27 & 28 are ground, while pin 25 is the +12V supply. Pins 26, 24 & 23 are marked “V SAW”, “V AGC” and “V RAMP”, respectively. I checked the voltage on pin 26 and it was correct at 4.85V. Pin 23 was also correct at +1.22V but when I checked pin 24, it read +5.5V instead of +7.16V – a difference of 1.66V! Obviously, when I placed my finger on these pins, pin 25 (+12V) was able to pull pin 24 high enough to substantially correct the distortion. The only component on pin 24 was C409, a 1mF 50V polyester capacitor (Part No: ECQV1H105JM3), so I removed it and checked it on my meter. There was no leakage and the value was remarkably accurate. Despite this, I replaced it anyway siliconchip.com.au 1 3 2 TRANSLATION 1: Does the donkey have a passport? 2: I need a stiff drink you idiot 3: Where’s the nosebag and, as they say in the movies, that was that. The picture was now perfect, I was happy and, eventually, so was Mrs Roseberry. But what a rotten fault – little wonder I needed a stiff drink afterwards! Transported from Spain Mr Julio Sanchez had brought his 2000 Sony FD Series Trinitron KV32FX65E TV set (AE-5 chassis SCCQ14K-A) all the way from Spain. It was a multi-system TV, so he had no problem installing it here in Australia. However, it must have been fairly expensive to import, this being an 82cm widescreen set weighing 64kg. Everything had been fine for Julio, except that he lived near the beaches and wasn’t aware of the risks involved for his beloved telly. When his set died, he really wanted us to call but I told him that the AE-5 chassis was not a common Australian model and that it would be better if he brought it into my workshop (the closest Australian model is a KV-EH36M31 using an AE5A SCC-U61A-A chassis). Reluctantly, he finally arranged for it to be delivered and when I switched it on, the only thing I got was the front red LED flashing four times. This norsiliconchip.com.au mally denotes a vertical protection fault, which could be due to R6835 or R6834 (0.47W) which supply the ±15V rails respectively, or perhaps IC6700 (STV9379) on the D Board going short circuit. However, I considered these possibilities unlikely in this case, as I couldn’t see any sign of the EHT starting (which is where these voltages are derived). I started making measurements and found that there was +135V from D6617 but none on the collector of horizontal output transistor Q6804 (2SC5480-01). This was because R6895 and R6896 (0.47W) were open circuit, while Q6815 was short circuit. When replacing Q6804, I also found that C6815, a tuning capacitor, was invisibly dry jointed – ie, it looked soldered but the pigtail had not been properly inserted into its hole and was just resting on the entrance (incidentally, Q6804 can also be a 2SC5696). This restored everything and the set was then soak tested to make sure there wasn’t anything nasty lurking about (such as the flyback transformer intermittently arcing). The warranty job We had a rather involved repair on a 2004 Panasonic TC-21PM50A TV set employing a GP3 chassis. It arrived in the workshop with the fault label saying it was “dead” but no-one had thought to ask how (or when) the problem had occurred – eg, was it the result of a thunderstorm? The set was still under warranty, so I decided to tackle it the same day. When I opened it up, I immediately saw that resistor R801 (2.2W) which acts as a surge limiter to the bridge rectifier had blown open. In addition, the chopper (IC801) had been destroyed, along with 82V zener diode D820. But that wasn’t the end of it and I soon discovered that optocoupler D860 and the IC802 (SE140) had also been damaged. And as I progressed through the set, more and more major damage was discovered, particularly along the 12V rail which had received a full 140V when Q850 (and R850) went short circuit. This not only took out several electrolytic capacitors (including C862, C880 and C2380) but also IC851 (a switching IC regulator supplying 5V and 8V) and also almost every other semiconductor along this rail. At this stage, after consulting a Panasonic Technical Officer, it was decided August 2005  49 Serviceman’s Log – continued East-West correction circuits fitted and when the correct circuit diagram was examined, a link plug and socket (TPA23, 24 & 25) which switches in various capacitors in the horizontal deflection circuit was discovered. This link was missing on the new chassis and fitting a link from the old one over the appropriate test point reduced the width to an acceptable level. The widescreen JVC that the chassis was a write-off – it would be just too expensive and time consuming to fix. And so a new one was ordered and fitted to the set. However, I wasn’t out of the woods yet. The width was now too large (ie, it was overscanning) and there was no sound or picture – only a raster! Fortunately, this no-sound, no-picture problem was easily solved. One of the ceramic filter’s legs was shorting to ground because the solder pigtails hadn’t been cut short and had subsequently bent. An attempt to fix the overscanning problem was initially made by entering the Service Menu Self Check Mode 3 – ie, by setting the off-timer to 30 and simultaneously pressing RECALL on the Remote and Channel Up on the TV front panel, then selecting CHK3 by pressing 2 on the remote. When EWWIDTH was subsequently selected by button 4, the OSD (on-screen display) showed that was changed using the Volume “+” and “–“ controls. In this case, however, the picture scan width didn’t change. Comparing the two chasses, we could see differences in the flyback transformer, so I swapped them just in case. It made no difference! Finally, the penny began to drop. This chassis model didn’t have any 50  Silicon Chip Frank Small was a round jovial character and I liked him even more when he brought his set in himself, rather than demand a service call. This was no mean feat, as the set was one of those heavy flat widescreen jobs – in this case, a 2001 JVC AV-28STEKGR using a JK chassis. Its problem was that it would try to come on but it just couldn’t make it. The only sign of life was the rush of the EHT static just before it cut out. Obviously, the protection circuits were closing the set down but was it a faulty protection circuit or a real fault that was triggering them? The service manual showed that pin 28 of microprocessor IC701 was the protect control pin and that in the normal state, it should be held high at +4.8V via R767. However, in Frank’s set, this pin was at zero volts. Desoldering it allowed the set to fire up and give a normal picture and sound, so what was causing the problem? The protect line branches out all over the set and is in turn connected to the four power supply outputs via zener diodes, to the flyback transformer protection transistor (Q592) and to the x-ray protection transistor Q593. Each of these lines had to be investigated in turn. I made a lucky guess by starting with the x-ray protection transistor. When I shorted its base to its emitter, the collector voltage immediately rose rise to 4.8V so I was on the right track. This transistor was being biased on by voltage from D593, R595 and D594, which in turn is fed by R524 from pin 8(AFC) of the flyback transformer T551. I dusted down the oscilloscope and checked the waveforms of the line pulses on six pins of the flyback transformer and compared them with the service manual. Interestingly, all the waveforms were 10V higher than published (ie, 70V peak-to-peak instead of 60V). I then measured the main HT rail (B1) as +145V, which was spot on. The size of the line pulses is determined by the values of the capacitors in parallel with the line output transistor (Q521, 2SD2553-LB), so these were the next to be checked. I started with C521 (2.8nF, 1.5kV), which I removed and measured with a capacitance meter. It read just 0.2nF or 200pF which meant it was almost completely open circuit! Replacing it restored the correct waveform sizes and switched off the protection circuit. Frank was a happy man – even after paying my rather modest bill. A couple of Grundigs It seems that now Grundig is no longer a German company, I am called on to repair more of them – even though Grundig Australia is still apparently flourishing and supporting their products with excellent aftersales service and technical support. I had a couple of examples turn up recently, the first being a 1999 Grundig Xentia 72 Flat MF 72-490/8 Dolby set (CUC1832 chassis). Due to their complexity, these sets do not lend themselves to being fixed in the home and I was grateful that its owner delivered it to the workshop. The complaint was that the picture was “half and half” – it was intermittently breaking up, was fuzzy, couldn’t hold its tuning and there was a “colour chromatic bullseye” effect. Well, with these descriptive faults, I couldn’t wait to see the effects for myself. However, when I switched the set on, it was intermittently unstable, particularly in the horizontal axis, and the picture locked in with the sync bar down the centre. But what was more alarming was a burning smell and the noise of something arcing. I switched the set off immediately and took a look at the main PC board. I soon identified the culprit as C53012, a 142pF 2kV capacitor on the collector of the line output transistor (T53001). This capacitor feeds 100V line pulses to the L1 line and these become the AFC reference pulses that are fed to siliconchip.com.au the Feature Box Module (pin 28) and onto pin 26 of CIC 1410 SDA9362 S-DDC. I replaced this capacitor and fixed the burnt hole in the PC board the original dry joint had created. This fixed the fault before I had a chance to see all the interesting symptoms described by the set’s owner but at least it prevented further possible damage to other parts. The second Grundig set was a 2000 Elegance 82 Flat MFW-82-3110 MV/Dolby unit (CUC 1935 chassis). Unfortunately for me, its owner, Mr Trump, requested a service call – a not unreasonable request in view of the fact that this is 76cm widescreen set was located on the second floor of a block of units. The set was “dead”, although the multi-coloured LED did manage to change from red to amber when I attempted to fire it up with remote control (Tele Pilot 110C). I couldn’t see anything obvious initially and because access was so poor in the confined space, I eventually decided it would be better to remove the chassis and take it back to my to workshop. Once on the bench, I soon found that the line output transistor (T53501, 2SC5331) had gone short circuit. In addition, R55514 (a 4.7W 2W fusible resistor) had gone open circuit, while pin 5 of IC55510 (TDA8145), the east-west correction amplifier, had gone short circuit to ground (pin 4). Replacing these parts was somewhat difficult due to their location in the chassis and because of this, I fitted an IC socket – just in case. However, the job was eventually done with just a little fiddling. Now the trouble with running a chassis on the bench without the deflection yoke is that there can be some unexpected consequences, due to the tuned circuit no longer being tuned and the tolerances of the components involved. To start with, I had to short out pins J3 and J4 of the deflection yoke plug in order to apply +A (142V) to the line output stage. I then shorted the base and emitter of T53501 together with a crocodile clip lead and hung a 60W globe off the collector to ground. Overwhelmed by inactivity When I switched it on, I was overwhelmed by inactivity. Nothing happened and I was getting no voltages out of any of the 13 secondary voltage rails. The only activity I had was the LED which still didn’t go beyond amber. I had already checked the eight fuses fitted to the chassis and had confirmed there were no shorts on any of these rails. And so, having no prior experience with this model, I decided to ask Grundig Technical Support for a bit of a hand. When I got through, I was obligingly told that I had to override the protection circuits (since the chassis was out of the set). To do that, you have to desolder pin 2 of the centre optocoupler (OK60546) or disconnect the base of CT61585 by desoldering link BR199. I asked about running the chassis without the deflection yoke but the Grundig technician didn’t know that I had linked pins J3 and J4 and therefore said it would be OK (my mistake for not telling him). Well, the voltages did come up but the line output transistor blew again and the same resistor and IC also failed, plus a 315mA fuse (SI52501) to the line driver stage, for good measure. However, with no 142V being siliconchip.com.au August 2005  51 Serviceman’s Log – continued have caused the initial problem. In the end, I cleaned the picture tube glass and the cabinet, as well as the transformer and anywhere else I thought might be a problem, until the visible arc from the static rush disappeared. That done, I accessed the service mode (by using code 8500) but could find no error codes. I left it at that – there was no point pursuing software options as I had the set working satisfactorily. In short, it was best to let sleeping dogs lie. After soak testing, the set was returned to Mr Trump with a warning to keep it dry and to cover it when he wasn’t watching it, to keep the saltladen air off the circuit boards. Ailing Naim CD player What’s this? Answer – it’s the control board for an LG vacuum cleaner. As you can see, it carries some fancy-looking electronics and it’s cheaper to replace the board than fix it! applied to the line output stage, all the voltages came up correctly. I went to a lot of trouble to try and find out what “U COPY MODE” meant or was supposed to do and how it was tied up with “U STANDBY” and the “CIC21660 74LV00 quad AND gate”. However, in the end, I only succeeded in confusing myself. Next, I removed and checked all 11 tuning capacitors in the line output stage. I also removed the flyback transformer and tested it with an HR Diemen simulator but could find nothing wrong with any of these parts. Finally, I decided the only option 52  Silicon Chip I had left was to bring the rest of the TV back to the workshop, despite all the logistics that involved. Ironically, after connecting the chassis back to the picture tube and yoke, the set fired up perfectly. There were no signs of stress anywhere, the voltages were all correct and the LED turned green. Lots of static The only niggly thing I noticed was that there was an awful lot of static between the picture tube and the plastic cabinet every time you switched the set on or off. I phoned Grundig Technical Support once again and this time was put right as to what I had previously done wrong. And the technician confirmed that there is only one earth lead from the CRT aquadag to the chassis, via the picture tube socket. We both agreed that it could be salt deposits from onshore sea breezes that were causing the static problem and I was advised to either clean or replace the flyback transformer, which might We had a Naim CD3 compact disc player in for repair recently. This is basically an upmarket version of the popular Philips/Marantz CD56 series. These can occasionally suffer from intermittent distorted sound and this is normally due to IC6305 – the DAC (digital-to-analog converter) – becoming temperature sensitive (too hot or too cold). Alternately freezing and heating this component will soon reveal whether or not that’s the problem, as it seemed to be in this case. A new one was fitted (well, actually we fitted the Philips TDA1541P which costs just $15) but it didn’t fix the fault. This DAC is supplied by +5V, -5V and -15V rails, all of which were correct. However, the CRO revealed that there was substantial ripple on the -5V rail (VDD2 on pin 26), caused by the failure of capacitor C2344 (47mF). When freezing the IC, the capacitor must have been hit too, causing a change in the symptoms. Anyway, we replaced capacitors C2344 and C2325 and reinstalled the original (more expensive) DAC chip. A soak test of the unit then showed that all was now OK. Vacuum cleaner Finally, I enclose a photograph of a common household appliance. As you can see, it looks pretty sophisticated with all those ICs. But what is it for? Answer: believe it or not it is the control board out of an ordinary LG vacuum cleaner! Furthermore, it is cheaper to replace the board than fix it. SC Where will it all end? siliconchip.com.au [ August 2005 ] GORE HILL HAS EXTENDED ITS WEEKDAY TRADING HOURS! 7.8" Roof Mount Widescreen TFT LCD Monitor Includes horizontal swivel mount! It folds up out of the way, or down to entertain your passengers. It has integrated dome lights in the console, so you can replace your factory interior light with this unit. It accepts standard composite video signals, is powered straight from 12VDC, and has a remote control too. Supplied with connecting / mounting hardware Cat. QM-3758 and an IR remote $ .00 control. 329 9 / 18Hr Digital Voice Recorder with USB A must for people on the go! Wether you are a student or a busy executive, a voice recorder will help you take notes, record important information, and a whole lot more. The simple push recording function allows quick start up so you don’t miss a thing. Audio can be downloaded via USB, and there are too many features to list here. Check out our website Cat. XC-0283 $ .00 for full details and specs. 169 Proximity Security Beeper Never lose valuables again! The Proximeter transmitter attaches to your valuables, and you keep the receiver in your pocket. If you walk away from the transmitter, it will beep, reminding you to grab your possessions. Cat. GG-2375 $ .95 29 10W Megaphone Make yourself heard! Made from high-impact ABS plastic, it is as durable as it is functional. Ideal for schools, crowds, and more. It weighs less than 2kg, so it is not too tiring on the arms. Cat. AM-4058 Includes shoulder strap. $ .95 119 Eye Mask with Massage/ Air Pressure/Heater Stress relief! Alleviate eye fatigue caused by extensive use of computers, long periods of driving, studying and reading. It can provide a massage, gentle air pressure, and warm compression. See website for full details. Our Gore Hill store is now open from 7.30am till 6.30pm Monday to Friday (and 7.30am – 8.30pm Thurdays), so you can drop in before or after work! BARGAIN BAGS ARE BACK! Stock won’t last! You know you love ‘em. We have a limited quantity of 2kg bargain bags filled with all sorts of goodies. Stock simply won’t last, so get yours today! 13.8V 20A Switchmode Bench Power Supply Huge current! Ideal for testing and running high drain low voltage equipment such as car audio, marine accessories, and automotive gear. It is a must for serious Cat. MP-3078 $ .95 lab work. See website for details. 99 19 KIT OF THE MONTH "Clock Watchers" LED Clock Kit This clock is hypnotic! Ref: SC June 2005. It consists of an AVR driven clock circuit, and also produces a dazzling display with the 60 LEDs around the perimeter. It looks amazing, but can’t properly be explained here. We have filmed it in action so you can see for yourself on our website, so check it out! Kit supplied with double sided silkscreened plated through hole PCB, and all board components as well as the special Cat. KC-5404 EXCLUSIVE clock housing. $ .00 TO JAYCAR This kit enables you to make a full-sized electronic scoreboard, in particular for Basketball but also adaptable for netball and other games. Ref: Silicon Chip March/April/May 2005. It can be built for a fraction of the cost of commercial equivalents and has a completely wireless scoring console that can control one or multiple scoreboards. You can mount the scoreboards high up in a court and all you need is a convenient 240V power point. You can then control them from a table courtside with no messy wiring. It features Home/Away team scores 0 to 199, Game period, and Countdown time. The scoreboard measures 900 x 600mm. •The Jaycar kit comes complete with all pre-cut scoreboard woodwork, screen printed face, display filters, mounting plates, pre-programmed microcontroller, printed circuit boards, 2.4GHz transmitters and receivers, pre-punched control console with special piezo end-of-game/quarter sounder, and all electronic components to make one scoreboard. 129 Inductance / Capacitance / Frequency DMM Very versatile! One of our latest additions to our range, this DMM is packed with features to make it an amazing meter on the go, or in a lab. Features include: •10A current. •Temperature. Cat. QM-1324 •High accuracy. $ .95 •Holster included. Superb quality! With such an amazing array of features, you would normally expect a price tag of much more. Just check out the features! •Duty cycle. •Relative measurement. •RS-232 data logging. •Double moulded. •Auto ranging. •Frequency. Cat. QM-1537 $ .95 FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 Cat. XB-9000 $ .95 True RMS Auto Ranging RS-232 DMM 99 We have held the release of this scoreboard kit for a very good reason. We have revised the design to add in a few trick new features including provisions for fouls. Now this may not seem like much, but it is now on the scoreboard and the control panel, which we think is an invaluable feature. Check out the website for all the details on this great kit that is now even better. EXCLUSIVE TO JAYCAR! Wireless Basketball Scoreboard Kit 49 Cat. GG-2262 $ .95 Where have all the scoreboards gone? INTERNET> www.jaycar.com.au Cat. KC-5408 $ .00 799 Additional Scoreboard Expand the possibilities! The control console can operate more than one scoreboard, so you can have one on each end of the court. Additional scoreboards contain Cat. KC-5409 everything included in the original kit, $ .00 without parts for the control console. 649 4 Channel USB Datalogger No more serial! Record DC and slow-moving signals over very long periods. It connects to a PC via the USB port to display real time information, as well as record it. No additional power is required. There are four DC-coupled input channels, monitored at up to 100 samples/second (globally). It has a host of great features, just check out our website. Cat. QD-5000 $ .95 139 99 1 19 Key USB Numeric Keypad Central ADSL Line Filter Great for laptops! One key feature that doesn’t come with a notebook computer is the numeric keypad. Sure it is overlayed on other keys, but it just isn’t the same. This unit is compact and Plug n Play, so it is very easy to use. Cat. XC-5155 $ .95 29 Relax at your computer! The USB powered device contains lavender scented wax that fills your workspace with a calming fragrance that is said to soothe the mind and heal the body. Works with your own fragrances too! Cat. GH-1044 $ .95 iPod USB Data Cable Attention PC users! A replacement cable for a lost or broken iPod data cable. Works with all iPods that use the 30 pin Apple connector. WC-7692 Commonly used on Windows Cat. $ .95 computers. 14 iPod Firewire Data Cable Cat. WC-7690 $ .95 iPod Car Charger 14 Charge on the go! Connects to your car’s cigarette lighter socket to charge your iPod via the Apple 30 pin Cat. MB-3650 connector. $ .95 Great for travellers. 19 iPod Data / Charging Cradle and Cables Very useful! Charge and update your iPod easily with this cradle. It will charge the battery and you can connect the USB or Firewire cable to update your playlists etc. Cat. XC-4930 iPod not $ .95 included 300k Pixel SurfCam USB Web Camera Video conferencing and more! It uses a 300k pixel colour CMOS sensor with auto exposure and white balance for optimum performance. Software included for creating greeting cards and photo albums. Cat. QC-3223 $ .00 35 USB Powered Battery Charger Cat. XC-4950 $ .95 19 2 5 Button Scroll Mouse 69 Massive portable storage! Instantly add gigabytes of storage to your PC or notebook. You can use any 2.5" IDE HDD, and then plug it into your USB 2.0 port for super fast backup, transfer, and storage. Includes carry pouch, cable, and drivers (only required for Win98). No flat batteries, no sore muscles! Charge your mobile phone from your USB port, or ease away the stress of the day. It suits Nokia, Siemens, Samsung, and Sony Ericsson phones. Cat. XC-4678 $ .95 49 Cat. GG-2268 $ .95 12 7 Port USB 2.0 Powered Hub No more plugging and unplugging cables! This high speed hub features powerand indiviual port LED indication. It is self powered, with a 5V mains plugpack included. Was Cat. XC-4823 SAVE $69.95 $ .95 59 $10 Notebook Docking Station No more cable tangles! Leave your peripherals connected to the dock, and just plug/unplug a single cable! Includes 4 port USB 2.0 hub, Ethernet, serial, and 2 x PS/2 connections. Cat. XC-4860 $ .00 139 USB Radio and Remote Control Radio on your PC! Receive, play, and record FM radio stations through an ultra-stable phase-lockedloop (PLL) tuning system for superior reception. Cat. XC-4880 Includes an IR remote control which $ .95 can also be used with software such as MS PowerPoint. 79 USB Wireless PC Security Lock Simple PC security! Keep the small transmitter with you, and when you are out of range (around 2m), it puts your PC into "lock mode". When you return, it resumes normal operation. Transmitter, receiver, Cat. XC-4842 software and drivers $ .95 supplied. Was $69.95 Ideal for voice recognition! It can sit on your desktop, or be attached to your monitor. It produces low noise and has a wide frequency response for more natural sound. 3m lead Cat. AM-4087 to 3.5mm plug. $ .95 12 USB Phone Charger / Mini Massager 49 Very handy! Not only is this a handy USB 2.0 flash disk, it also houses a card reader than can read Memory Stick, Secure Digital, and Multimedia cards. Fully compliant with USB 2.0 specification for ultra fast data Cat. XC-4750 $ .95 transfer. Desktop Multimedia Microphone 2.5" IDE - USB 2.0 Hard Disk Drive Case Great New iPod Accessories! Recharge your batteries while you download your photos! Why use another mains outlet when you can utilise the USB power at hand. Charge up to 4 x AA or AAA, Ni-MH or Ni-Cd batteries. 28 19 19 29 Cat. YT-6096 $ .95 Replace that tired old mouse! This optical PS/2 mouse doesn’t suffer from "dirty ball" problems thanks to its optical design, with fast resolution for Cat. XM-5119 $ .95 ease of use. USB Aromatherapy Diffuser Attention Mac users! A replacement cable for a lost or broken iPod data cable. Works with all iPods that use the 30 pin Apple connector. Commonly used on Macintosh computers. 128MB USB 2.0 Flash Disk with Memory Card Reader Simple brilliance! This central line filter allows multiple phone connections to eliminate huge numbers of individual filters sometimes required when using ADSL services. Surge and overload current protection. TV/Video Capture Systems HIGH DEFINITION Digital Terrestrial TV Card for PCs HDTV on your computer! Watch either high or standard definition TV on your PC! It supports wide-screen (16:9) and standard (4:3) aspect Cat. XC-4819 $ .00 ratios. 179 USB 2.0 HIGH DEFINITION Terrestrial TV Tuner for PCs Top quality reception! No need for physical hardware installation, just plug it into your USB 2.0 port for HDTV. It operates in enhanced 16:9 format with software supplied for DVD making and Cat. XC-4814 manipulation. See our website for $ .95 system requirements. 249 XPERT DVD Maker SAVE Convert all your old VHS tapes and $20 camcorder cassettes to DVD! XPERT DVD Maker converts on the fly, so there is no need for excessive amounts of free disk space. All you need is a DVD Cat. XC-4811 $ .00 burner and you can store your memories forever!Was $149 129 USB 2.0 DVD Maker No more fading memories! Transfer all of your VHS, Betamax, and camcorder tapes to DVD using your computer’s DVD burner. With editing software to add colour and transitional effects, as well as sound tracks. Supports composite Cat. XC-4809 SAVE & S-Video inputs & PAL or $ .00 $20 NTSC sources. Was $149 129 USB 2.0 Video Capture Box SAVE $20 Streaming full resolution video on your PC! Preview, record and playback video, or burn to CD or DVD. This is a great way of making DVDs if you own an analogue video camera. Includes capture Cat. QV-3090 and editing software, supports MPEG1 $ .00 and MPEG2. 99 FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 INTERNET> www.jaycar.com.au Great New HDMI Leads and Accessories The latest technology! The High Definition Multimedia Interface (HDMI) provides high quality signals for the best reproduction quality. HDMI Connecting Cables Male to male connection Cat. WQ-7400 1.5m Cat. WQ-7402 3.0m Cat. WQ-7404 5.0m $39.95 $49.95 $64.95 HDMI to DVI Cable Cat. WQ-7406 3.0m $39.95 HDMI Adaptors Cat. PA-3640 HDMI Socket to Socket Cat. PA-3642 HDMI Plug to DVI-D Socket Cat. PA-3644 HDMI Plug to DVI-D Plug $14.95 $14.95 $14.95 1 Farad 20V Capacitor with Voltage Display Car audio enthusiasts please note! This massive capacitor will help stabilise the voltage levels in a high power stereo installation. A voltage display keeps you informed of voltage levels, and mounting hardware is included. Cat. RU-6750 $ .95 Analogue to Digital Audio / Composite to S-Video Converter Video conversion works both ways! This processor converts analogue to digital audio, as well as composite video to S-video and vice versa. It offers optical and coaxial digital audio outputs, which supports the sync record function. 9VDC power supply included. Cat. AC-1612 $ .95 89 Frequency Selectable RF Modulator Excellent versatility! Traditionally RF modulators could only be used on channels 0 or 1. This is fine for many applications, but if you already have a VCR or other device tuned on those channels, it is a problem. This unit allows you to select which channel to Cat. LM-3878 $ .95 tune into. Mains plugpack included. 49 Car Super Tweeter Bargain 99 Carbon Fibre Subwoofers New range! Featuring high quality Carbon Fibre cones and dual voice coils, these new subwoofers offer great performance and durability. •See website for full details. 10" Subwoofer •250WRMS power handling. •Dual 4-ohm voice coils. CS-2278 •87.1dB sensitivity. $ 179.95 Fantastic value! They have a frequency response of 6 to 20kHz and 40WRMS power handling. Cat. CS-2218 Limited Qty $ .00 ea Was $5 SAVE $1 ea 4 UHF Wireless Stereo Headphones No more limitations! Walk freely around your home listening to your favourite tunes. Up to 100m range. Use internal rechargeable Cat. AA-2000 SAVE batteries. $ .95 $30.05 Was $109 78 4 Way Optical Switch Box 12" Subwoofer •300WRMS power handling. •Dual 4-ohm voice coils. CS-2279 •88.2dB sensitivity. 219.00 $ LCD Virtual Goggles Take the cinema screen with you! Enjoy private viewing of your TV/DVD/VCR or games console with these lightweight goggles. So portable they can be used in a car to enjoy DVD player entertainment, or connect it to a video games console such as PLAYSTATION, XBOX, etc. Supplied with Cat. QM-3790 cables and power adaptor. 800 x 225 $ .00 (180,000) pixel resolution. SAVE Was $399 $50 349 MPEG4 Media Player Great for the car or home! Here is a great way to enjoy movies, music, and picture slide shows on your TV or PC monitor. It accepts many common memory cards so all you need to do is load the files on the card, pop it in and you're away! The IR remote control operates all functions, including great features such as image zoom, image rotate, slide shows, and various other great functions. It supports MPEG4 encoded files in MPG, DAT, and AVI format, and Cat. XC-4865 $ .00 can also play music and image files. See our website for full details. Measures 125(W) x 22(H) x 83(D)mm. 199 Simple solution! Optical signals cannot be electronically switched, but this switch box provides a solution. Four inputs (1 x 3.5mm, 3 x Toslink), 1 Toslink output. 19 2.4GHz Wireless Audio Video Sender Watch cable TV all over the house! Send a signal from a DVD player, set-top box etc., to another room, without the use of any cables! You can use as many receivers as you like, without degrading signal quality. Each unit comes supplied with stereo audio and video transmitter and receiver, mains plugpacks & RCA cables. Transmission range is up to 100m, but depends on the type of construction materials used. Was $99 Cat. AR-1832 SAVE $ .95 $29.05 69 Extra receiver to suit Cat. AR-1833 Was $69 Cat. AR-1833 $ .95 49 SAVE $19.05 2.4 GHz Wireless A/V Sender with Remote Control Extender With the addition of an IR remote control repeater you can change the channel of the source device etc from Cat. AR-1830 the other room. $ .95 Was $139 Extra receiver to suit Cat. AR-1831 Cat. AR-1831 $ .95 Was $89 FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 Cat. AC-1675 $ .95 INTERNET> www.jaycar.com.au 89 SAVE $49.05 69 SAVE $19.05 Don’t Miss Out! RIBBON TWEETERS Affordable at last! Spectacular U.S. Stock Purchase All Audiophiles know that ribbon tweeters are the ultimate speaker for smooth high (and very high) frequency performance. Unfortunately, a good ribbon tweeter can cost between $100 and $500 - to thousands for some custom German ones. Even high-end enclosure manufacturers all opt for dome tweeters simply because "ribbons" add too much to system cost. Jaycar have made a massive stock purchase from a major US organ manufacturer who makes both pipe and electronic organs. They are an 80+ year old company and we cannot tell you who they are! They are restructuring their production of their high-end organs and their stock of ribbon tweeters has been sold to us far, far below the 10,000+ factory gate price! Their massive loss is your gain. The product. The tweeter is made in Japan by the venerable manufacturer, Foster. The device itself has multiple ribbon "diaphragm" components in same-phase configuration. There are two basic types of ribbon tweeters, static or dynamic type. This product is the dynamic type which has conventional impedance 8Ω and is more efficient. Each speaker is supplied with a datasheet and securely packed. Even if you do not have any specific need for a ribbon tweeter at the moment, we strongly urge you to consider purchasing it for future use. At the price we are offering, we expect OEM (manufacturer) interest. As it is a distress stock buy, quantities are limited. On many occasions in the past we have warned customers of this and the slow ones miss out. Finally, we think that technically, two tweeters per enclosure would be the way to go. They should not be overdriven. Note also the fairly high crossover frequency. In keeping with this suggestion, we have a special price for a set of 4 pieces. Type: Regular-phase 100mm ribbon tweeter Power: 20 Watts RMS (cont), 50W max. SPL: 92dB/Watt. Freq Resp: 6K-40KHz +/-2dB (SUBLIME!). Impedance: 8Ω. Crossover Frequency: 6,400Hz (12dB / Octave). Normally a speaker of this quality would sell for over $100. Because the factory’s loss is your gain we are offering this product for only $39.95 each, or a set of 4 for only $136 – only $34 each! You will KILL yourself if you miss out and you will if you delay. Cat. CT-2023 $ .95EA 39 or buy as a set of 4 for $136.00 That”s only $34 each! 3 Piece Surround Sound Add-On Enjoy the surround sound experience. The centre speaker contains a screened 4" mid/woofer, and 2" tweeter with a 6 ohm impedance. The two rear speakers contain a 4" full range with a 4 ohm impedance. 2004 Cat Price $99.95 Cat. CS-2465 SAVE $ .95 $45 54 3 5 in 1 Dynamo Power Bank with Radio and Lamp Very versatile! Not only does this dynamo powered device have an AM/FM radio and incandescent lamp, there is a host of other functions. There is a 3, 6, 9, and 12VDC output socket to provide emergency power, and a plugpack can also be used to charge the internal battery. It also has two-way charging; wind the handle to charge your car battery, or let you car battery charge it! Cat. ST-3370 59.95 $ Novelty Pocket Lie Detector The truth is out there! Tell a lie and you get a low score, tell the truth and get a high one. There is no way out! Powered by 2 x AA batteries, and measures just 150(L) x 110(W) x 40(D)mm. Cat. GT-3060 29.95 $ Go Ballistic! - Novelty Target Game Just like in games parlours! This is a mini game where you launch a small ball from a miniature catapult and try to get it through the high scoring holes. There are two modes of play, and are hours of fun. See website for details. Cat. GT-3062 39 $ .95 Luminiferous Message Board A message pad with a difference! Switch it on and watch your message light up. Great for shopping lists or birthday wishes, and a whole lot more. Can be set to off, on, or flashing. Measures 280(L) x 232(H) x 15(D)mm. Cat. XC-0199 29.95 $ Remote Sound Effects Boxes! Scream Machine with 6 Sounds A great gag! Scare the daylights out of someone when you activate the scream box. It will shriek one of six sounds out loud, and they won’t know it is Cat. GH-1083 $ .95 you pressing the button! 19 Giggle Machine with 6 Sounds Do you tell a good joke? Even if you don’t you will get a laugh out of this box. Just press the remote control for one of six amusing giggles to get everyone Cat. GH-1085 laughing. $ .95 19 Fart Machine with 6 Sounds Our best fart machine yet! With twice as many realistic sounds as our regular model, this new fart box is sure to shock everyone at a party Cat. GH-1087 with disgusting $ .95 realism! 19 4 STOP PRESS STOP PRESS STOP PRESS STOP PRESS STOP PRESS 1GB Portable MP4 / MP3 Player with Voice Recorder / FM Radio and Picture Viewer Check this out! This blows conventional MP3 players and solid state flash disks out of the water! At first glance, you might think that it is just an MP3 player with an LCD screen, but that is just the tip of the iceberg. This unit is feature packed, just check out the line-up! •MP3 player of course, the most obvious feature, the 1GB capacity allows storage of a few hundred songs! •JPEG picture viewer - you can run slideshows for you and your friends - great in this digital age. •Built-in FM radio - so you can catch up on the news, or listen to the latest chart-topping hits. •Voice recorder - so you can take voice notes or record conversations (with permission of course). •MPEG-4 player - so you can watch full length movies on the go! It measures just 75 x 37 x 14mm, and weighs less than 40g! Cat. GE-4006 NOW AVAILABLE The 1.3" high resolution TFT LCD screen provides crystal clear $ .00 pictures, and is the perfect way to keep yourself entertained. See website for full details. 399 STOP PRESS STOP PRESS STOP PRESS STOP PRESS STOP PRESS Mini Digital Video Camera Recessed Colour LED Lights Fantastic price! A This easy to use camera digital video fits in the palm of your camera for hand! under $200! The recorded video can be transferred to a computer for editing, or simply viewed directly on any TV with AV inputs. Supplied with camera bag, cables and software. •3.1 mega pixel software resolution for stills. •1.5" colour LCD screen. •5 layer glass lens. •32MB internal memory SAVE •SD/MMC expansion slot $50 •4x digital zoom Cat. QC-3230 •Internal microphone $ .00 Was $249 and lots more! 199 Pedometer with 128MB MP3 Player Time flies when you're exercising! This pedometer has a built-in MP3 player which stores up to two hours of music. More than enough for most fitness programs! Pedometer functions include calorie counting, distance monitor, as well as a clock. Supplied with USB Cat. GE-4012 cables and earphones. $ .95 •68(L) x 39(W) x 22.5(H)mm 119 Pedometer with FM Radio and Calorie Counter Keep track of your calories! You can input the food you have eaten, and it will count down how far to go until you have walked it off. Many other functions, see our website. Cat. XC-0267 19.95 $ “Norbert” Robotic Vacuum Cleaner Sit back and relax while your IMPROVED robot cleans the house! MODEL It automatically moves around obstacles, and an intelligent optical sensor assists in avoiding walls & obstructions. Works best to supplement your Cat. GH-1395 SAVE $ .00 manual cleaner, not $50 replace it. Was $249 Spare Dust Filters Pk 2 Cat. GH-1396 $29.95 Mop Papers Pk 100 Cat. GH-1397 $24.95 199 Illuminate in style! They are great for illuminating paths, driveways, and even floors because they mount completely flush. Mains powered, the lights measure 27(H) x 30(Dia)mm. Can be expanded to 10 additional lights. ST-3887 4 pcs white pack ST-3885 White Cat. ST-3887 Cat. ST-3885/6 $ .95 $ .95 ST-3886 Blue 89 19 Alcohol Breath Tester with LCD Readout Stay safe and under the limit on the roads! This unit is very compact & features an integrated LCD to give you an actual readout of your blood alcohol content. While providing a good indication of BAC, it should not be relied on for precise results, and you should never drink and drive. Cat. QM-7294 69.95 $ The Amazing Flygun! Keep the kids entertained! The Amazing Flygun is a safe, fun, and effective method of killing flies and mosquitoes. Launch the spring powered swatter at your target! It is safe, fun and really does work! Cat. YS-5545 SAFE $ .95 FOR AGES 8 AND UP 7 Rechargeable 40 Channel UHF Transceiver Great range, great features! Since the outstanding success of our popular DC-1010 transceiver, it only SAVE seemed logical to $30 refine the design, adding a few enhancements along the way. It is a lot more compact, measuring just 53(W) x 95(H) x 32(D)mm. It uses a small rechargeable battery pack, and is supplied with a dual charging cradle. You can still of course use AAA batteries as a backup. Four step scrambling is also provided for private communications, making this transceiver just plain fantastic! Supplied with one Buy a transceiver and a charging DC-1025 with cradle. Was $89.95 an extra transceiver (DC-1028) for just Cat. DC-1025 $99.90! Save $60! $ .95 59 FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 INTERNET> www.jaycar.com.au SAVE ON RECHARGEABLE BATTERIES! Under Cabinet Alarm Clock Great in the workshop! This alarm clock can bolt under an overhead cabinet, or simply sit on a desk. It includes an AM/FM radio so you can wake up to the morning news or a simple buzzer. Mains powered. SPEND $25 and SAVE $25! Spend $25 or more on any combination of Ni-MH rechargeable batteries – singles or packs - and you will save $25 on this NiMH battery charger! What a great deal! Cat. XC-0248 24.95 $ Colour Changing Digital Alarm Clock Looks great! Get rid of your boring alarm clock and grab one of these! The colour changes every hour and it has a large LCD for easy viewing. Displays time, alarm time, as well as calendar information. Mains Cat. XC-0254 $ .95 plugpack supplied. SAVE $5 $3.59ea $12.95pk $15.95pk $5.95ea $19.95pk $12.95ea $24.90ea $12.95ea SAVE $10 $ SAVE $3 Small, sleek, and stylish. A unique rubber stand moulds to any shape to suit all surfaces. Clock face size is Cat. XC-0216 $ .95 81(H) x 55(W)mm. Was $17.95 14 14.95 $ BOTH TYPES 19.95 $ Create your own dance party atmosphere! Get your party started the right way with some creative lighting to help set the mood. Just add music and you’re set! All mains powered. Kit contains: •20cm mirror ball. •1RPM mirror ball motor. •PAR36 spotlight. •PAR36 globe. •4 x coloured gels for PAR36. 39.95 Digital Map Distance Calculator Cat. GT-3006 29.95 $ Cat. SL-2978 69.95 $ Lighting Clamp Sturdy mounting! Lighting clamps are used for securing pinspot lights and accessories to lighting stands. Measures 78(L) x 45(D)mm. Cat. SL-2969 PAR36 Spotlight with Colour Wheel and Motor 4.95 $ Set the mood! The advanced screw-cap globe holder design, which is much better than the older spring-clip style which were clumsy. The 245mm fivecolour wheel and motor is easily mounted for simple installation. •Globe not included. Use SL-2964 $9.95 Cat. SL-2963 44.95 $ 19 49 Super bright! Strobe lights are at home in the clubs and on the dance floor, and have been very popular for many years. This unit features a super bright 75W flash tube and can be timed with music or independently. Cat. SL-2999 See website for full details. Designed $ .95 for domestic use only. 79 Mini Electric Toy Safe More compact! This mini version of our regular toy safes has keypad entry and great sound effects. It measures 132(L) x 105(H) x 122(D)mm, and A great way has a coin slot to save pocket in the top. money! Cat. GH-1312 19.95 $ Electronic Toy Safes 4 Way Light Chaser with Sound Modulator Simple but effective! When music is playing, it switches in time with it. There are no modulation controls, but it works quite well indeed. It uses 240V 60W ES reflector lamps, supplied with a red, yellow, green, Cat. SL-2942 and blue globe. Check out our $ .95 website for replacements. INTERNET> www.jaycar.com.au 19 A touch of luxury! Wash away the cares of the day - no matter how far from civilisation you are! The camping shower allows you to take a shower wherever you are. Cat. YS-2800 Powered by your $ .95 vehicle’s 12V battery. Heaps of power! Great for theatrical and effects lighting, it includes an adjustable mounting bracket, quick change gel holder, and an 800mm mains lead. Cat. SL-2974 •Globe not included. $ .95 Use SL-2977 $34.95 FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 How far is the next turn off? Automatically convert a map’s scale distance to real distance by rolling the small wheel along the desired route. It works with any map scale Cat. XC-0375 $ .95 and displays in kilometres or miles. 12V Camping Shower PAR56 300W Spotlight 75W Strobe Light Hands full? No worries! Just wave your hand, foot, or whatever you can, in front of the intelligent rubbish bin and the lid will open automatically! It will also close back up again, so you never need to touch it. 23L capacity. Cat. GG-2315 $ G R E AT N E W PA R T Y LI G H T I N G R A N G E ! Disco Party Light Set Very handy! If you carry alot of batteries, or just like things to be organised, then get these. Each case holds 4 x AA batteries, and there are two cases supplied. One red and one blue. Intelligent Automatic Rubbish Bin Great fun for the whole family! The missiles launch spectacularly into the air with the use of the hand pump. They launch over 30m into the air! Cat. XC-0160 59 3.95 Air Powered Rocket Launcher and Pump Disco Alarm Clock Just $34.95 with a $25 battery purchase Save $25 $ SAVE $10 Were $29.95 Great versatility! Run it off 12V in the car, or mains when you’re at home. It has loads of cell protection and features to make it as safe as possible, with automatic trickle charging. Cat. MB-3507 See website $ .95 for full details. Cat. HB-6359 Radio Controlled Submarines Great underwater fun! They have full manoeuvrability with forward, reverse, left and right, and a power dive function. Two types available: 27MHz Yellow GT-3044 40MHz Blue GT-3045 12VDC / 240VAC Intelligent Fast Charger / Discharger for Ni-MH / Ni-Cd Batteries 4 x AA Battery Case - Pack of 2 19.95 Was $29.95 9 An alarm with a difference! Wake up to upbeat disco tunes instead of the usual screeching that we all know and love. Measures 155 x 130 x 125mm. Limited qty SAVE Was $29.95 $15 SB-1723 SB-1739 SB-1737 SB-1727 SB-1735 SB-2429 SB-2460 SB-2467 Swims underwater! It has full manoeuverability with forward, reverse, left and right and a power dive function. Cat. GT-3225 For every basketball fan! Throw it at the wall to turn the alarm off! You can’t play ball with it, but it is fun to wake up to. Cat. XC-0159 100mm diameter $ .95 Was $14.95 Desk Clock with Alarm and Calendar AAA 900mAh Ni-MH Batteries AAA 900mAh Ni-MH 4 Pack AA 2000mAh Ni-MH 4 Pack AA 2400mAh Ni-MH Batteries AA 2400mAh Ni-MH 4 Pack C 4500mAh Ni-MH Batteries D 9000mAh Ni-MH Batteries 9V 200mAh Ni-MH Batteries Radio Controlled Clown Fish 24 Basketball Action Clock Buy $25 worth of these.... ....and get $25 off this! 69 Ideal protection against… siblings! Features an illuminated keypad and programmable combination, with voice or sound effects. Pink Cat. GH-1310. Blue Cat. GH-1311 •185(H) x 135(W) x 125(D)mm. BOTH TYPES 19.95EA $ 5 8 Port Digital Surveillance Capture Card 4 Input IP Sensor Modules 50 fps capture! Using the power of two separate cards, it can deliver high quality streaming video through your PC, and you can view it from a local or remote location. It records up to a global rate of 50 frames per second so you won’t miss any of the action from slow recording rates. It also has an audio input and requires Cat. QV-3059 two PCI slots in your PC. $ .00 See website for details. Security over the Internet! This 4 input sensor can be given an IP address so you can monitor the state of the inputs from anywhere in the world with an internet browser. It can be used for PIRs, alarm sensors, lights, and more. Password protection, polarity protection, and Cat. LA-9040 more included. $ .00 See Cat page 327 for full details. 399 Professional Metal Detector Lightweight and easy to use, it has a visual and audible indication for detection, and optional momentary operation. It is a Cat. QP-2273 $ .95 must in this security conscious age. Measures 410(L) x 85(W) x 20(D)mm. 99 Hand Held Tally Counter Remote Control - Power Door Locking SAVE $10 A touch of luxury! Take the hassle out of locking and unlocking doors when parking, or to keep your kids safer in the back seat. These kits are durable, and easy to install. Two and four door lock kits available: Two Door Kit Four Door Kit Includes 1 master, 3 slaves, control relay, hardware, wiring. Cat. LR-8812 Was $39.95 SAVE $10 16 Expand the system! Buy an extra colour Cat. QC-3606 $ .00 receiver QC-3607 with your video doorphone for just $199. Save $150! 399 Cat. LR-8810 $ .95 24 Cat. LR-8812 $ .95 29 Ideal for tenants! The system is supplied with a control panel equipped with keypad, and a built-in siren. It also comes with a wireless PIR, reed switch, and panic Cat. LA-5125 button which operate $ .00 within a 50m range. There are also provisions for hard-wired expansion if desired. See our catalogue page 326 for details. 199 Shed / Garage / Boat Alarm Very affordable! The garage or shed can often be neglected when it comes to security, but often there is valuable machinery and tools inside. This unit consists of a reed switch for the main door, and a PIR for general protection. Keyfob arm / disarm. Includes mains plugpack, 10m cable, and a battery backup option. 199 USB Pan / Tilt PC Camera with Remote Access This is one of the most useful PC based cameras we have seen! It has full functionality as a pan/tilt camera, with motion controlled via the serial port! You can log onto a preset IP address, and actually take control of the pan/tilt functions. Software and drivers are supplied on CD-ROM, and it is compatible with Windows 98,SE,ME,2000, and XP. •640 x 480 pixels resolution. •Colour CMOS sensor. •111(L) x 97(W) x 86(H)mm approx. Cat. QC-3395 Was $399 SAVE $ .00 $100 4 Channel Multiplexing DVR with 120GB HDD and Ethernet The new age is here! Now you can have a regular DVR in use for surveillance around the home or office, while having the ability to view streaming video from anywhere in the world via an internet connection. You can get peace of mind on holidays or check up on your kids. •Digital recording with wavelet compression. •10/100 Base-T Ethernet connection. Cat. QV-3072 $ .00 •Full control from remote location •720 x 576 pixels (PAL) •Video loss detection •See website for specs. 999 Realistic Dummy Dome Cameras Extremely realistic! Both models can have standard board cameras fitted to make them real working cameras. Cat. LA-5312 Corner Mounting $ .95 Dummy Camera 29 Metal mounting for stability. Cat. LA-5400 $ .95 P R OT E C T Y O U R H O M E O R O F F I C E ! A Quality and Comprehensive Security System No contact required! Control entry to a doorway, or an entire building. The unit can be used in a network of locks administered by a central location, or just to control access through a front door. It is 12V powered, so you can use it in remote locations, and the reader unit is splash proof. 5 RFID cards included. •N.O. and Cat. LA-5120 N.C. relay $ .00 contacts. 299 3 Zone Wireless Home Alarm Kit Power Door Locking Kits for Cars $5 Cat. LA-5018 $ .95 Top quality! The colour camera, and LCD screen give you excellent clarity to the picture. Supplied with all mounting hardware and wiring. 9 Includes 1 master, 1 slave, control relay, hardware, wiring. SAVE Cat. LR-8810 Was $29.95 Select your style! Choose from one of 32 different melodies with the touch of a button. The weatherproof wireless transmitter is easily mounted, and the receiver is powered by 3 x AA batteries, so no wiring is required. Colour Video Doorphone Simple operation! Easily count crowds through a gate or nightclub door to make sure you don’t pass legal operating capacity. Simple to use, it counts up to 9999. Cat. TC-2500 $ .95 The base can be removed for pocket use. 69 129 Wireless Doorbell with 32 Melodies Great for nightclubs! Keyless entry! Enjoy the luxury of keyless entry no matter how flash your car is. Simply wire this unit up to your central door locking (factory or one of our kits), and you can wirelessly activate Cat. LR-8831 the actuators. $ .95 Ltd qty. Was $79.95 RFID Access Control System Cover all bases! The Melcom 8 sector alarm system offers all the features of higher priced units, without the extravagant price. It has an Austel approved dialler built in, so you can be remotely alerted to the alarm being triggered, without the wildly over-priced monitoring fees that some security companies charge. The panel offers 8 separate zones, with handy programmable features such as exit / entry delay, zone naming, and more. The user panel features a display to assist with intrusion zone detection and programming, and a whole lot more. While you can purchase just the panel and keypad, the best way to get setup is to buy one of our package kits. The LA-5428 consists of all the parts to get you started. Here is exactly what you get: •1 x Melcom 8 sector alarm panel with dialler and keypad. •3 x Proton quad PIRs. •1 x 7Ah backup battery. •1 x Strobe light. •1 x Siren cover. Cat. LA-5428 •1 x Outdoor speaker siren. •1 x Indoor siren. •2 x Reed / magnet assemblies. $ .00 •1 x 100m 6 core approved alarm cable. •1 x 30m roll of 2 core cable. •4 x Deterrent stickers. 49 Dome Dummy Camera with Right Angled Bracket Highly noticeable for Cat. LA-5311 $ .95 maximum deterrent. 19 SPECIAL DEAL FOR AUGUST ONLY! Not only do you get the Melcom 8 Sector alarm deal at the fantastic price of $749, but you also receive 20% OFF any additional reed switches, PIRs, or alarm cable that you purchase at the same time. GREAT VALUE! 749 6 FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 INTERNET> www.jaycar.com.au NEW HARDCORE ELECTRONICS! Genuine Panasonic Brand 3V Lithium CR-2032 Cell - 10 Pack A great price, but there's a catch! We have made a great surplus buy of fresh, genuine Panasonic brand Japanese lithium Limited cells. These cells, Quantity however, have PCB mount pins attached via very light spot welds. You can mount the battery on a circuit board with the pins - or you can easily remove the pin terminals by grinding the spot welds off with an engraver. Why bother? To save big money, that's why! Panasonic CR2032 batteries normally cost $6 to $7 each.. This month buy a pack of 10 x CR-2032 for only $20! That's only $2 per battery! Even if you don't use them immediately the long shelf life will keep them fresh for up to 10 years. Cat. SB-1764 $ PKT 10 20 IEC320 to Mains Socket – UPS Lead Here at last! After countless requests we have a lead to plug mains Cat. PS-4100 devices into a UPS $ .95 which has IEC320 sockets. 150mm long. 9 Coax Seal Tape No more water ingress! Seal your outdoor coaxial connections to prevent moisture entering the connectors which hampers signal quality and causes corrosion. Simply wrap it around the connector and cable, and it will turn into a removable water Cat. NM-2828 resistant seal that lasts for years. $ .95 •12mm wide As used by NASA and the US military •1.5m length. 9 2 x Digit LCD Display – BARGAIN Genuine AAVID/Thermalloy TO-220 Heatsink Clips Very versatile! These are a TO-220 heatsink clip on with a dissipation of 18.8°C per watt. •Push-on type. Cat. HH-8505 •Pack of 10. $ PKT 10 •Limited quantity. 8 Powertech Switchmode Power Supplies Affordable quality! Priced well below our current range with the same features and durability. See website for individual specifications. MP-3160 MP-3162 MP-3165 MP-3167 MP-3170 MP-3172 MP-3174 MP-3175 MP-3179 MP-3180 MP-3185 MP-3187 MP-3189 MP-3250 $44.95 $44.95 $54.95 $54.95 $59.95 $59.95 $64.95 $69.95 $69.95 $99.95 $94.95 $94.95 $94.95 $169.95 Simple tester for a simple problem. Don’t get caught with a faulty spark plug. Bright neon Cat. QP-2264 illumination indicates $ .95 spark presence. 5 90 - 300VAC / DC Voltage Tester Cat. KJ-6696 $ .95 49 HKZ-101 Hall Effect vane Jaycar has it back! Previously obsolete, the HKZ-101 has been commonly requested, but difficult to find since Siemens deleted it in 1998. This copy is almost identical, and works very well. See our website for data. A quick go / no go indication. Great for simply testing to see if a wire is live. High quality Cat. QP-2240 insulated probes, $ .95 neon indication. 3 GPO Mains and Earth Leakage Tester Cat. ZD-1900 $ .95 19 Make GPO installation and checking a breeze! Identifies problems with wiring, and checks earth leakage circuit breakers using Cat. QP-2000 selectable trip $ .95 current. 19 1000V 7 Piece Screwdriver Set IDEAL Non - Contact 60 to 400VAC Tester Great for every tradesman’s pocket! Gives an audible and visual indication on energised circuits. It has an Cat. QP-2274 unlimited lifetime $ .95 warranty, and is rated at CAT III 600V. 29 GS and VDE tested and approved. Soft rubber grip handles, with insulation right to the tip. CHECK THIS GREAT PRICE! FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 4 4 25W 12VDC 25W 24VDC 40W 12VDC 40W 24VDC 60W 12VDC 60W 24VDC 60W 5/12VDC 100W 12VDC 100W 24VDC Open Frame 120V 5/24VDC 150W 12VDC 150W 15VDC 150W 24VDC 240W 12VDC INTERNET> www.jaycar.com.au Cat. TD-2022 $ .95 19 1 Farad 5.5V Super Capacitor Massive capacity! These are high capacity 1 Farad capacitors made by ELNA in Japan. Very useful for 5V memory retention in volatile chips. PCB mount. Cat. RU-6705 $ .95 Special introductory price! Awesome value! Classic 7 segment x 2 LCD with 0.1" PCB pin connection. Includes datasheet. Limited quantities Cat. QP-5514 available. $ .00 Neon Spark Plug Tester Wind Powered Generator Experimenters Kit A great learning tool! This small scale project enables you to build a real working wind generator, and then use it for experimenting. It can supply up to 10VDC <at> 100mA (depending on wind speed), and features an on-board 0.3F capacitor so you can store the energy for later use. Kit includes all parts to make the generator, fan assembly, and pedestal. Stands 250mm high. This section is dedicated to what’s new for the Hardcore Enthusiast. VELLEMAN Pic Programmer / Checker Versatile! Supporting 8p, 14p, 18p, and 24p PIC microcontrollers, this board is quite versatile. It includes test buttons and LED indicators for on-board experimenting and testing, as well as programming software. Includes a PIC16F627. Cat. XC-4402 $ .00 119 HK-828 45 Second Voice Recorder IC Great for projects! The HK-828 voice recorder IC is a great low-cost record/playback device for use in many projects. There are loads of great applications and data sheets are on our website. This IC is used in a voice recorder project, Cat. ZZ-8200 described in Silicon Chip $ .95 Magazine, May 2005. 19 See page 8 for the kit. Encapsulated Toroidals •Low magnetic stray field emissions. •Low standby current. •Low profile. •Magnetic shielded. •Fully encapsulated. •See website for details. 3.2VA 12V MT-2030 3.2VA 18V MT-2032 7.0VA 12V MT-2036 7.0VA 18V MT-2038 3.2VA 7.0VA 7.0VA 24V MT-2040 $ .95 $ .95 19 22 STOP PRESS STOP PRESS STOP Attn: All You “Tim The Toolmen” (The Wealthy Ones Anyway) We now stock the USDesigned Grabit damaged screw removal tool, but BOY it’s expensive!! What it does. If you have a typically, (but not necessarily) countersunk screw that is slotted, Phillips, Posidrive, Torx, TriWing, tamper resistant, etc that is totally stripped out, this product will get it out even if the head is totally hollow! All of us “Tims” have experienced this! The extraction bit consists of a burnishing bit that basically preps a tapered hole in the screw head. You turn the bit around with the extractor bit out, reverse the cordless drill direction and the extractor bit bites into the prepped hole with tremendous force. Works equally well on brass, steel, stainless screws etc. If your time is money, this product is worth it. If you are just a “weekend warrior” like most of us you will have to think hard about the price. It will remove a screw that is breaking your heart but, boy you will pay. The TD-2059 consists of two 1/4” hex drive bits that cover screws from #6 to #14 gauge. They come in a small plastic case with instructions. In days when a 12V cordless drill can retail for $25 this product may seem Cat. TD-2059 expensive. What it can do for you, over $ .95 and over again is priceless. 49 STOP PRESS STOP PRESS STOP 7 VELLEMAN USB Controlled Interface Kit The New Flexitimer Kit More accurate and versatile! Ref: Silicon Chip August 2005. We have seen many timer kits over the years (just look else where on this page!), but nothing as exciting as this. The new kit is PIC microprocessor controlled and features a friendly user interface making it much simpler to use than previous designs. This also gives it excellent accuracy and added flexibility. You can program times up to 99mins 59secs, and even two times with a selection to alternate up to 99 times (so you could set periodical on/off periods for many applications. Check out our website for the full details. Kit includes PCB, silk screened and Cat. KC-5415 machined case, LCD, & all electronic $ .95 components. As easy to program as a microwave oven timer! No parallel, no problems! This interface kit offers 5 digital and 2 analogue inputs, as well as 8 digital and 2 analogue outputs! That is plenty for experimenting and interfacing with your home or devices in many ways. It is powered straight from the USB port, and even has on-board test functions. The kit is supplied with all components, silk screened PCB, assembly manual, and software. Cat. KV-3600 $ .95 You will not be disappointed. MIDI Theremin Synthesiser Kit 69 Voice Recorder Kit Recording flexibility! Ref: SC May 2004. Record and playback up to 60 seconds of audio, all under the control of a PC or microcontroller. Variable Cat. KC-5412 sampling rate allows quality selection, $ .95 and more. Kit supplied with PCB, voice recorder IC, and all electronic components. 39 Lead-Acid Battery Zapper Kit Extend the working life of your lead-acid battery! Ref: SC July 2005. This simple circuit is designed to produce bursts of high-energy pulses to help reverse the damaging effects of sulphation in "wet" lead-acid batteries. This is particularly useful when battery has been sitting for a period of time without use. Its effects are dependant on the battery’s condition and type, but the results can be quite good indeed. Kit supplied with case, silk Cat. KC-5414 screened lid, leads, inductors $ .95 and all electronic components. Exclusive to Jaycar! Ref: Silicon Chip April / May 05. Instead of generating a Theremin like tone, it relies on a MIDI accessible synthesiser or a Bass Extender Kit computer with a An extra octave of bass response! sound card. Ref: Silicon Chip April 2005. This When set up SMS Controller Kit project boosts the level of bass (usually with a Control appliances from anywhere! to counteract the frequency computer), it Ref: Silicon Chip Nov 2004. roll-off of your loudspeaker will play up to 120 different The SMS controller kit works enclosures, effectively giving instrument selections in 15 types, by 8 with Nokia 3210, 3310, 5110, you an extra octave of bass response. variations. There are loads of features and functions, and 6110 models to control Kit includes PCB and all too many to list here, so check out our website or the Cat. KC-5400 electronic outputs, and gives you a Cat. KC-5411 electronic components. Silicon Chip articles for full details. Kit supplied with $ .50 $ .95 host of control options. The possible YOUR LOCAL JAYCAR STORE PCB, case, LCD, and all electronic components. uses are almost endless! Kit includes Cat. KC-5410 NEW SOUTH WALES PCB, pre-programmed micro, and all electronic $ .00 AC/DC Current Clamp Meter Albury Ph (02) 6021 6788 components. Requires Nokia data cable. Alexandria Ph (02) 9699 4699 Kit for DMMs Bankstown Ph (02) 9709 2822 The SHORT CIRCUITS LEARNING SYSTEM A cheap alternative! Bondi Junction Ph (02) 9369 3899 The Short Circuits learning system is a great way to learn Ref: SC Sept ’03. It Brookvale Ph (02) 9905 4130 electronics. It is fun, informative, and you build great works with your Campbelltown Ph (02) 4620 7155 Erina Ph (02) 4365 3433 projects along the way. Here is just one from Short Circuits 3… DMM just like a Hornsby Ph (02) 9476 6221 professional clamp meter. Guitar Practice Amplifier Kit Cat. KC-5368 Newcastle Ph (02) 4965 3799 Kit includes PCB, case, Don’t annoy the neighbours! $ .95 Parramatta Ph (02) 9683 3377 hall effect sensor, pre-cut Penrith Ph (02) 4721 8337 It has a guitar type input socket, small speaker, and volume control. It Cat. KJ-8092 core, and electronic components. Silverwater Ph (02) 9741 8557 $ .50 sounds great! Kit supplied with PCB, speaker, socket, and all electronic St. Leonards Ph (02) 9439 4799 components. Instructions are in the Short Circuits 3 book. Sydney City Ph (02) 9267 1614 Fuel Mixture Display Kit Taren Point Ph (02) 9531 7033 Theremin Synthesiser Kit Is your car The "Flexitimer" Kit Wollongong Ph (02) 4226 7089 Far cheaper than commercial units! running right? VICTORIA A must have! Ref: SC Aug ’00. The Theremin Synthesiser Coburg Ph (03) 9384 1811 Ref: SC Nov ’95. It Ref: EA March Frankston Ph (03) 9781 4100 produces those familiar science fiction movie ’91. 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KC-5382 electronic $ .95 components. $ .95 components. 89 39 49 19 159 34 14 14 18 59 29 7 24 8 PRICES VALID TO END AUGUST 2005 49 FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 INTERNET> www.jaycar.com.au Featurescontrol of external/recirculate air • Automatic le) here applicab vent in car (w aler t: n O concentratio • Two-level C D LE l flashes Warning leve and triggers lly lights LED fu l ve Alarm le tput DPDT relay ou y operation or toggle rela ry ta en om M • justments and alarm ad ng ni ar w e at steresis • Separ alarm level hy d an ng ni ar w • Adjustable justment calibration ad ut tp ou or ns • CO se anual reset • Optional m ion • 12V operat mode • Circuit test Carbon Monoxide ALERT By John Clarke Carbon monoxide is an insidious poison which can – and does – kill. It’s colourless, odourless and sneaks up on you! The first time victims become aware of carbon monoxide poisoning could be too late. C arbon monoxide (CO) is a pretty simple gas, consisting of one carbon and one oxygen atom. It will eventually mate with a spare oxygen atom and reform into the more natural – and relatively harmless – carbon dioxide, or CO2. But it remains as CO more than long enough to cause real harm to us mere mortals! Moreover, carbon monoxide poisoning can be very difficult to treat. While carbon dioxide (CO2) is not poisonous as such (in fact the air we breathe naturally contains around 0.03% carbon dioxide), in sufficient quantity it can displace oxygen in the air and therefore cause suffocation. However, carbon monoxide (CO) in any significant quantity is poisonous because it affects the carrying of oxygen in our blood. One of the main problems is that CO has 200 times greater affinity with the haemoglobin in your blood siliconchip.com.au than does oxygen. It literally stops the blood supply from carrying oxygen around the body and, most importantly, to the brain. When the brain suffers from oxygen starvation, permanent damage and even death can result in an amazingly short time – just a few minutes. Therefore, even if there is a relatively good supply of fresh air, a relatively small concentration of CO in that air places you in significant danger. Where vehicles are concerned, CO is almost always accompanied by exhaust fumes which do have an odour, so preventative/remedial action can hopefully be taken. But if you’re a smoker (with already elevated CO levels in your blood) or suffering from an allergy such as hay fever, there is a real chance that your sense of smell might be compromised enough not to notice. August 2005  61 So you really need to avoid breathing in CO. The effects of this dangerous gas. You don’t have to spend $$$$$$ on also tend to be cumulative – the body can get rid of it over a luxury car – just a few $ on this ingenious kit. time but prolonged exposure can be deadly – literally. Our Carbon Monoxide Alert monitors the level of CO You may have seen those signs in tunnels and deep, gas and warns if it reaches danger levels. It has an earlylong cuttings asking you to turn off your car engine during warning flashing LED for low CO concentrations and an delays. There’s a good reason for that – unfortunately, the alarm output that is set for a higher CO concentration level. signs are ignored by many. A continuously lit LED indicates the alarm and a relay is If you have ever been caught in heavy traffic, you may switched on. have noticed that you are becoming tired and developing a The relay contacts can be used to power a siren or it can headache. While the frustration of sitting in traffic may be be used to switch the vehicle’s cabin air vent switch from affecting you, this is probably not the reason for your indispoexternal to recirculate so that outside air does not enter sition. In fact, these are classic symptoms of exposure to CO. the cabin of the car. In this last application, the CO sensor The table above shows needs to be mounted the effects of exposure outside the cabin so to CO gas against the Effects of CO gas poisoning and symptoms that it monitors outconcentrations in the side air rather than 50ppm Exposure for a few hours normally does not result in any air. It is likely that the cabin air. symptoms CO concentration will When used to con100ppm Exposure for a few hours results in a slight headache (usually rise to greater than trol the air vent, the in the forehead) 100ppm in heavy trafCO Alert can operate 500ppm Exposure for one hour results in a headache with increasing fic and perhaps even one of two types of severity over time more if the number of external/recircula1000ppm Exposure for 20-30 minutes results in a headache, dizziness cars ahead of you do tion controls found and nausea, with possible death within 2 hours not to have a catalytic in cars. These are the 4000ppm Exposure results in possible death within 30 minutes converter in their exelectrically-activated haust system. types that typically Modern cars with catalytic converters will produce concontrol a solenoid, allowing pneumatic actuators to open siderably less CO gas than their older counterparts and this or close the vent. The CO Alert is not suitable for controlis because one of the functions of the catalytic converter ling manually operated sliders that physically move the is to convert the CO gas into CO2. The conversion is done vent to open or closed positions. using a platinum catalyst that aids in converting the exhaust There are two types of electrically activated vent conproducts of hydrocarbons and CO into CO2 and water. trols. One is a push-on/push-off switch and the other is While overall CO levels may be on the decrease, there the momentary switch that toggles between external and are still relatively high levels in the air along main roads; in recirculation for each pressing of the switch. This last type fact anywhere there is a concentration of vehicles with their is the typical switch used with climate control systems. engines running. Areas where the exhaust gases are not well For use with a push-on/push-off switch, the CO Alert will ventilated can also be a problem – such as underground and switch on its relay whenever there is an alarm condition. high-rise car parks, tunnels, garages and sheds. External/recirculation control is then possible by wiring There are two ways CO can build up inside your car. The first is where the car PURGE PURGE PURGE exhaust system has holes or leaks that al5V low the exhaust gases to leak into the car CO cabin via poorly fitting seals around the SENSOR door or via open windows. To prevent this, HEATER 60s 90s 60s 90s 60s 90s VOLTAGE it is recommended the exhaust system be periodically checked for leaks. 1.4V The second way is from other vehicles’ exhausts. Think about it: you are sitting in TIME a line of traffic (whether stopped or moving) LOW and the exhaust pipe of the vehicle ahead of you is directing the flow of exhaust gases (including CO) away from that vehicle – CO straight towards yours. SENSOR OUTPUT If your air intake is set to “fresh” you aren’t RESISTANCE taking in fresh air at all: you’re sucking in the fumes of the cars in front! In slow or stopped traffic, the only safe option is to switch your HIGH air intake to “recirculate” or to turn the fan/ TIME air conditioner off completely. FRESH AIR (0ppm CO) (100ppm CO) In some of today’s luxury cars, a sensor Fig.1: the CO sensor goes through a 150-second cycle, purging itself automatically detects carbon monoxide levfor one minute then looking for carbon monoxide during the next 90 els and switches the air input from outside seconds. When CO is detected, its output resistance drops significantly. to recirculate, thereby avoiding a build-up 62  Silicon Chip siliconchip.com.au It’s larger than life but this photo shows the completed PC board, ready for installation inside a case or mounting under the dash, as explained in the text. The carbon monoxide sensor is the cylindrical silver device, top right of picture. the relay contacts to this switch. Note that the car’s external recirculation switch should be kept set for the external position so the relay can take over when recirculated air is required. For use with the momentary switch, the CO Alert relay momentarily switches the relay both when the alarm switches on and also when it switches off. This will therefore duplicate the momentary switch action to select recirculate when the alarm is on and external air when the alarm goes off. The action should remain correctly in synchronisation, selecting recirculation for the alarm condition unless the car’s external/recirculation switch is pressed to change the settings. Synchronisation is also ensured because we have in- OPTIONS 12V IN RESET LK1 LK2 REG1 S1 5V WARNING/ALARM λ PURGE CONTROL (Q1) LED1 60/90 SECONDS TIMER (IC1) RB5 SENSITIVITY CO SENSOR COMPARISONS (IC1) AN2 RELAY DRIVER (Q2, RLY1, LED2) VR1 AN4 VR2 AN3 VR3 SET HYSTERESIS ALARM AN0 VR4 siliconchip.com.au AN1 VR5 SET HYSTERESIS WARNING LEVEL CONTROLS RELAY CONTACTS Fig.2: operation of the CO Alert is easiest to understand by referring to each of the functions in this block diagram. Most of these occur via microcontroller IC1. August 2005  63 REG1 7805 +5V OUT 10Ω IN 10 µF 16V 100nF 4 14 Vdd 75Ω E C 10Ω 1k B 11 AN4 MQ-7 CO SENSOR B H VR1 50k AN0 AN2 IC1 PIC16F88 100nF 4.7k 1k RESET S1 2005 RB7 17 LEDS K VR4 WARNING 10k SET RELAY1 K D2 1N4004 RELAY CONTACTS 1 NC COM NO A 2.2k TP5 AN1 RA6 18 RELAY CONTACTS 2 NC COM NO VR5 WARNING 10k HYSTERESIS 1k 15 A B C Q2 BC337 BC327, BC337 E 7 MOMENTARY OR ON/OFF LK1 SC  13 0V K λ LED2 TP4 1 – 100 µF A 16V VR3 ALARM 10k HYST. 2 TP1 1k +12V ZD1 16V 1W +12V TP3 AN3 A VR2 ALARM 10k SET 3 Q1 BC327 H A TP2 MCLR RB5 100 µF 16V K 1W + GND 100 µF 16V D1 1N4004 6 RB1 RB3 9 TEST LK2 E B C 470Ω RB0 Vss 5 A λ LED1 K CARBON MONOXIDE ALERT/ALARM 7805 MQ-7 CO SENSOR H B B A A H ZENER – + 1N4004 A K IN OUT GND Fig.3: for a complex circuit, it’s pretty simple! The PIC microcontroller takes care of most functions. cluded an alarm memory. This remembers the current alarm status so that if the engine is switched off while there is an alarm condition, the alert will momentarily switch the relay on when the car is restarted. This will switch the vent back to external air. This memory is then cleared, so if the engine is switched off and on again, the relay will not momentarily switch again. There are some cars that automatically select external air when the car is started. For this case, we have provided an option that disables the alarm memory feature. So regardless whether or not there was an alarm condition when the car is switched off, the external/recirculation settings will not be altered when the car is started. In any event, you can press the external/recirculation switch on the car at any time to change the setting if it somehow gets out of synchronisation. A reset switch on the CO Alert can be used to switch off the alarm and return the air vent selection to external. Other (non-vehicle) CO alarms We have concentrated on automotive uses for this project because that’s the primary “market”. But there is nothing to stop you using this alarm to warn of dangerous CO buildups, anywhere they are likely to be generated – in fact, it’s entirely practical! 64  Silicon Chip One application which springs to mind would be in caravans and mobile homes: every year there are reports of people being poisoned through the use of unflued heaters (or even gas stoves). Other suggestions would be around stationary engines such as power generators (especially as these are likely to be in confined spaces). Here the relay output could be used to turn on an exhaust fan. The CO sensor Detection of the CO gas in the air is possible by using a sensor that is specifically designed to be sensitive to this gas. The CO sensor is made up of an aluminium oxide ceramic tube that is coated with tin dioxide to detect the CO gas. Two electrodes are attached to the tin oxide layer to provide for measurement of the change in resistance with CO concentration. Tthe ceramic tube is heated with a coil to bring the sensitive layer up to the required temperature for CO sensing. In addition, the temperature is periodically raised beyond the normal measurement value in order to burn off impurities that may affect the readings. This purging is performed over a 60-second period, followed by a 90- second measurement period. The actual CO concentration measurement is made at the end of the 90-second measurement period. Fig.1 shows the cycle of events when making a CO gas siliconchip.com.au Fig.4: the component overlay (above) with a matching samesize photo (right). Between the two of these, you shouldn’t have any problems with construction. Watch polarity on the electrolytic capacitors and semiconductors. measurement. Initially the sensor has the full 5V applied to its heating coil for 60 seconds. This performs the purge. The resistance across the measurement terminals falls to a relatively low value during the purge. After purging, the heater coil is reduced in temperature by reducing the voltage applied to the coil to 1.4V. The measurement resistance becomes high at the end of 90 seconds when exposed to fresh air. If the sensor is exposed to air containing concentrations of CO gas, the measurement resistance will be lower than the fresh air concentration reading after the 90-second measurement period. Block diagram The block diagram for the CO Alert is shown in Fig.2. The sequence for sensor purging and measurement plus warning and alarm point detection is under control of a microcontroller, IC1. IC1’s RB5 output drives the purge control block to adjust power to the heater coil so that the CO sensor is supplied with the full 5V to the heater during the 60-second purge and with 1.4V during the 90-second measurement period. The sensor output is monitored at IC1’s AN2 input, while sensitivity to the CO concentration is adjusted using VR1. In operation, the sensor voltage at the AN2 input is compared with the settings at the warning AN0 input and the alarm AN4 input. If the sensor voltage goes above the warning setting but below the alarm setting, then the RB3 output will flash the warning/alarm LED on and off. Should the sensor voltage go above the alarm setting, the LED will stay lit. siliconchip.com.au When the alarm LED becomes lit, the alarm relay will also switch on if the option at RB1 input is set to on/off. If the RB1 option is set to momentary, then the relay will switch on for about one second before switching off again. When the sensor voltage goes below the alarm threshold, the relay will switch off for the on/off setting and momentarily switch on and off for the momentary setting option. Note that hysteresis has been included for both the warning and alarm settings. Hysteresis prevents the alarm switching on and off repeatedly or “hunting” when the sensor voltage equals the alarm setting. The levels on the AN1 and AN3 inputs respectively set this. Hysteresis alters the switching point for the warning and alarm settings so that the CO concentration must fall more than “just below” the warning and alarm settings before switching off these conditions. For example, with the alarm setting, the alarm condition will be set when the sensor voltage reaches the value set by the alarm input but will not be switched off until the voltage drops below the “alarm hysteresis” setting. Finally, input RB0 provides a test function. This cycles the purge/measurement cycle much faster than the normal 60s and 90s rate, enabling the circuit to be tested without having to wait for more than two minutes to see the effects of changing the settings. The circuit The circuit is made relatively simple because of the use of a microcontroller instead of discrete ICs. Without the microcontroller, we would have required at least three ICs August 2005  65 Parts List – Carbon Monoxide Alert 1 PC board coded 05108051, 120 x 60mm 1 plastic utility box 130 x 68 x 43mm 1 MQ-7 CO gas sensor (Jaycar RS-5615) 1 panel-mount momentary pushbutton switch (NO contacts) (S1) 5 2-way PC-mount screw terminals, 2.54mm pitch 1 12V DPDT 10A relay (RLY1) 1 cigarette lighter plug 1 18-pin DIL IC socket 1 mini heatsink, 19 x 19 x 10mm 1 M3 x 10mm screw and nut 12 PC stakes 2 2-way pin headers, 2.54mm pitch 2 jumper shorting plugs 1 300mm length of 10A dual figure-8 wire with polarity stripe 1 200mm length of hookup wire Semiconductors 1 PIC16F88 micro controller programmed with cosensor.hex (IC1) 1 7805 5V regulator (REG1) 1 BC327 PNP transistor (Q1) 1 BC337 NPN transistor (Q2) 1 16V 1W zener diode (ZD1) 2 1N4004 1A diodes (D1,D2) 2 5mm red LEDs (LED1, LED2) Capacitors 3 100mF 16V PC electrolytic 1 10mF 16V PC electrolytic 2 100nF MKT polyester (0.1mF – code 104 or 100n) Resistors (0.25W, 1%) 1 47kW* 1 4.7kW 1 2.2kW 1 470W 1 75W 1 10W 1 50kW horizontal trimpot (VR1) 4 10kW horizontal trimpot (VR2-VR5) (* – for testing/setup only) 4 1kW 1 10W 1W For external sensor mounting, add 2m 4-core cable For remote reset switch and LED add 1m 4-core cable plus 1 momentary push button switch with LED indicator plus considerably more resistors, capacitors, diodes and transistors. The extra features such at the momentary or on/off action of the relay, the alarm memory function and the test option would all have added more complexity to the circuit. Fortunately the microcontroller has allowed us to incorporate the complexity without adding to the circuit. Also the microcontroller can use an internal oscillator, further reducing the parts count when the extra accuracy of a crystal is not required. Output RB5 is used to control the purge/measurement cycle for the sensor. It does this by going low (to 0V), switching on transistor Q1 due to the base current now flowing through the 1kW resistor. The transistor allows the full 5V to be applied to the heater inside the CO sensor. 66  Silicon Chip This purge cycle lasts 60 seconds. After RB5 goes high (to +5V), so Q1 switches off. The heater is now driven from 5V via a series resistance of 85W. In conjunction with the 33W resistance of the CO sensor’s heating element, this sets the heater current to the recommended 42.4mA, with 1.4V across the sensor. The sensor’s measurement terminal A connects to the 5V supply, while the B terminal connects to ground via a 50kW trimpot and 4.7kW resistor. This resistance forms a voltage divider with the sensor terminal resistance and a voltage appears at terminal B that is proportional to the measured CO concentration. The 1kW resistor and 100nF capacitor filter any noise which may develop on this high impedance circuit, particularly if the sensor is mounted remotely. The alarm, warning and hysteresis settings are provided by trimpots VR2-VR5 respectively. These are each connected across the 5V supply so each can be adjusted from 0-5V. Typically, the settings trimpots would be set to around 1.5V and 3V respectively, while the hysteresis settings would be no more then 0.5V. Test points provide measurement connection points for a digital multimeter. The warning/alarm LED is driven via the 470W resistor and microcontroller output RB3. This LED flashes at a nominally 1-second rate during the warning phase. The LED stays lit during the alarm condition. RA6 drives the relay via Q2. When RA6 is at 5V, transistor Q2 switches on and powers the relay, which closes the common and normally-open contacts. LED2 lights to show whenever the relay is on. Diode D2 quenches the reverse voltage spike when the relay switches off after RA6 goes low. The reset switch ties input RB7 to ground when pressed. It is normally held high via an internal pull-up resistor when the switch is left open. LK1 and LK2 tie the RB1 and RB0 inputs low when these links are installed. If a link is left out, its associationed input is pulled high via an internal pull-up resistor. Power is 12V, supplied from the car battery – normally via a cigarette lighter plug. Diode D1 protects against reverse polarity connection and zener diode ZD1 limits transient voltages to 16V. The 10W series resistor prevents excessive current flow during the clamping action. REG1 provides a regulated 5V output for the circuit. The 100mF and 10mF capacitors decouple the supply. As mentioned, the CO Alert can be built either as simply a monitor that gives visual indication of the warning and alarm CO concentration levels. This version has the unit built into a box with the sensor, reset switch and indicating LEDs mounted in the box. Alternatively, it can be built to actively control the cabin air vents in a car where such control is possible. In this case, the sensor is mounted external to the car’s cabin and the warning/alarm indicating LED and reset switch are mounted on the car’s dashboard. The LED and switch can be separate items or you can use a combined reset switch and LED assembly for a neater job. The unit would be most easily powered by connecting to an ignitionswitched terminal in the fusebox. Construction Begin construction by checking the PC board. If you are installing it in a box, the corners will need to be shaped so it will clear the internal pillars in the box. siliconchip.com.au Install the resistors, making sure the correct value is placed in the shown position. You can use the accompanying resistor colour code table to check values or use a multimeter to measure the value. When installing the regulator and IC socket, make sure they are oriented correctly. You will note that we haven’t yet placed the microcontroller IC in its socket. Similarly, the electrolytic capacitors must be oriented with the polarity as shown on the overlay diagram. One trimpot, VR1, is a different value to the rest – check that it is correctly placed. Use PC stakes for the test points and for the sensor connection points. These stakes support the sensor above the PC board when used in the box and for connecting the wires in the remotely located sensor version. When installing Q1 and Q2, make sure that the correct type is placed in each position. The LED (LED1) can mount directly on the PC board (actually 23mm above the PC board) when used in the box. If used on the dashboard, either separately or within an indicator switch, use PC stakes to make wiring easier. Position and solder the terminals and Here’s one mounting option for the CO sensor – inside a case with the relay. LK1 and LK2 are made from 2-way warning LEDs clearly visible through the lid. Alternatively, you could header strip and jumper shunts. Attach the mount the PC board under the dash with the alarm outputs switching the heatsink to the regulator using a screw and air intake. nut. The heatsink is oriented with the fins as shown. be on and indicated by LED2. When mounting in the box, drill holes in the box lid for Wind VR1 back so TP1 reads 2.8V and the alarm LED the sensor, the reset switch and two LEDs. Also drill holes will go from always lit to flashing and the relay will in the side of the box suitable for the wiring entry to the switch off. screw connectors. Retest the operation in momentary mode with the Before moving on to the testing stage, give your finished jumper plug inserted at LK1. The relay should switch project a thorough check for soldering, component placeon for a second or as the alarm goes on and also as the ment and where appropriate, component polarity. alarm goes off. You can also test the hysteresis operation by setting voltTesting. age at TP3 and TP5 to a small voltage using trimpots VR5 Initially, solder a 47kW resistor across the A and B sensor and VR3 respectively. If you set the hysteresis too large, PC stakes. Apply power and check for 5V between pins 5 & 14 on the IC socket. If this is OK, disconnect power and Fig.5: here’s how to wire insert IC1. Set VR1, VR3 and VR5 fully anti-clockwise; VR2 the relay to to about three quarters of its travel (in a clockwise direcNC the vehicle’s tion) and VR4 at mid setting. Jumper plug LK2 is inserted COM air intake for the test mode and the LK1 is left open. NO switch, with Check voltages at the test points by connecting your both NO and multimeter common lead to TP GND and the positive NC types NORMALLY OPEN EXTERNAL/RECIRCULATION SWITCH lead to each of the other test points in turn. There should (CLOSE TO RECIRCULATE) covered. be about 3V at TP2, 2.5V at TP4, 0V at TP3 and TP5 and 0.5V at TP1. Check the trimpots settings if the values are not similar to these. Rotate VR1 until the voltage at TP1 is higher than the NC 2.5V set at TP4. LED 1 should now flash after a second or COM so. Wind VR1 back so that TP1 reads 2V and the LED will NO stop flashing. Note that there may be a one or two second delay in the switching. NORMALLY CLOSED EXTERNAL/RECIRCULATION SWITCH Rotate VR1 until the voltage at TP1 is higher than the 3V (OPEN TO RECIRCULATE) set at TP2. Now LED1 should stay lit and the relay should siliconchip.com.au August 2005  67 NC CARBON MONOXIDE ALARM NO C chamber is usually a good position for the sensor, as this is the “gathering point” for the air which enters +12V the vehicle. You will require four wires to make the A and B connections and NO GND the two heater connections on the C sensor. Insulate the terminals with heatshrink tubing to prevent any of NC the wires shorting to the chassis. The PC board can either be placed TP GND in a box or attached under the RESET dashboard as a free PC board and protected against shorting to the 05108051 chassis by wrapping it up in some bubble wrap or heatshrink tubing. Fig.6: same-size PC board pattern, as seen from the copper side, for etching your However, you will initially need own or checking commercial boards. access to adjust the trimpots. The diagrams show how to wire the alarm or warning may never switch off. This will be up to the air vent switch. For the push-on push-off switch, the case if the hysteresis is set to a larger value than the you need to find out whether the switch is open or closed warning or alarm trip points of VR4 and VR2. Typically, when the air vent is set for external air (some vents close hysteresis needs only be 0.5V or less. to act as a bypass to external air, others open to allow exYou can test the alarm memory by switching off power ternal air in). You can do this by setting external air and when the alarm is on. When the power is reapplied, the then switching off the ignition. Check for a closed or open relay should switch on for a second. If you do not want this switch using your multimeter set to Ohms. A low reading feature, then switch off power and press and hold down of less than one ohm will indicate that the switch is closed. the reset switch. Now turn on power while still pressing If the switch is open for external air, then connect the the reset switch. Release the switch after a second and common and normally open relay contacts across this the feature should be disabled. Check this by switching switch. The switch is kept in the open position. If the off power when the alarm is on. The relay should not switch is closed for external air, then the common and operate when power is reapplied. Note that pressing the normally-closed relay terminals connect across the switch reset switch during power up as before can reactivate the and the switch is pressed so that it is in its normally open memory feature. position for recirculate. Remove the 47kW resistor across the CO sensor stakes and For the momentary switch operation, external and rein their place, connect the CO sensor itself. Now connect circulation air control is invariably made with a normally your multimeter (set to measure low DC volts) between TP open switch. The common and normally open relay conGND and the top heater terminal. Check that this voltage tacts should be connected across the switch. goes from 5V to 1.4V to 5V etc every second or so. The test Calibration link (LK2) can now be removed. The manufacturer recommends that the sensor be purged There is no easy way to calibrate the sensor to specific for 48 hours. This is required to ensure accuracy of readings. CO concentrations. In general, you can set trimpot VR1 However, for our purposes, the CO Alert should be able to to mid setting and set VR4 to 1V and VR2 to 2V. Set the be used immediately, noting that readings may change after hysteresis trimpots (VR3 and VR5) to 0.25V each. Check several hours use, once the sensor has purged of impurities that the warning LED flashes when cruising in relatively introduced during manufacture or during storage. busy traffic and that the alarm LED stays lit in heavy stopstart traffic. Installation You can increase sensitivity to CO emissions by turnAs mentioned before, if the CO Alert is used to coning VR1 higher (ie, more clockwise). If the sensing is too trol the air vents, the unit needs to be installed with the sensitive, set the warning and alarm trimpots (VR4 and sensor mounted externally to the cabin. The plenum VR2) more clockwise. SC Resistor Colour Codes 1 1 1 1 1 1 1 No. 1 1 1 4 1 1 1+1 68  Silicon Chip Value 47kW 4.7kW 2.2kW 1kW 470W 75W 10W 4-band code (1%) yellow violet orange brown yellow violet red brown red red red brown brown black red gold yellow violet brown brown violet green black brown brown black black brown 5-band code (1%) yellow violet black red brown yellow violet black brown brown red red black brown brown brown black black brown brown yellow violet black black brown violet green black gold brown brown black black gold brown siliconchip.com.au Custom-made Lithium Ion, NiCd and NiMH battery packs Smart Chargers www.batterybook.com (08) 9240 5000 High-capacity 280mAh rechargeable 9V 2400mAh NiMH AA cells siliconchip.com.au High-quality single cell chargers with independent channels. Charge any combination of NiCd & NiMH AA and AAA cells High-capacity 9Ah rechargeable D August 2005  69 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. Vertical sync for the Component Video to RGB Converter Some video projectors with RGB component video inputs have separate inputs for vertical and horizontal sync, so these signals need to be separated before feeding them into the projector. This means that in order to drive these projectors from the Component Video to RGB Converter (SILICON CHIP, May 2004), a small amount of circuitry must be added to the converter to provide a separated vertical sync output. Note that the existing composite sync output can be used to drive the horizontal sync input of the projector. The additional circuitry is very straightforward, as you can see from the circuit diagram. It consists of an LM358 dual op amp, plus a 75W resistor and two 100nF monolithic ceramic capacitors. These can all be mounted on a small piece of Veroboard or similar and wired directly to an RCA socket (CON9) mounted on the converter’s back-panel. The extra socket can be positioned between the existing composite sync and red video output sockets. As shown, only one half of the LED noughts & crosses Here’s a twist to the age-old game of noughts and crosses. Instead of pen and paper, it uses nine 10mm tri-colour LEDs arranged in a 3 x 3 grid. One player has nine red buttons while the other player has nine green, set out in identical grids. The aim, of course, is to make three LEDs in a row glow the same colour – red or green! Pushing a red button causes the LED in the equivalent position on the grid to glow 70  Silicon Chip Right: the vertical sync signal is derived from pin 3 of IC5 via buffer stage IC6a. The output is wired to an extra RCA socket mounted on the rear panel. LM358 is used. It is connected as a unity gain buffer with its noninverting input connected to pin 3 of the LM1881 sync separator (IC5) on the converter board. This pin provides the vertical sync output signal. The only other connections between the additional circuitry and the converter board are for the ±5V supply and earth rails. SILICON CHIP. red in colour. Likewise, pushing a green button lights the equivalent green LED. If a player pushes a button for a LED that is already glowing red or green, then that LED changes to yellow, exposing the false move! All the LEDs are then turned off, ready for the next game, by pressing the “Clear” button. For simplicity, the circuit shows only one tri-colour LED and a pair of opposing buttons. This circuit fragment must be repeated another eight times to create a complete 3 x 3 grid. A brief press on a button fires the associated SCR and turns on the LED. The common (cathode) lead of all LEDs is connected to the 0V rail via the normally-closed contacts of the “Clear” pushbutton (S3). The SCRs are available from RS Components (stock no. 183-7695), on the web at www.rsaustralia.com or phone 1300 656 636. PC-mount tactile switches from Jaycar (Cat. SP-0720 & SP-0724) were used on the prototype. A. J. Lowe, Bardon, Qld. ($35) siliconchip.com.au Audio level threshold control This circuit was originally designed for use in detecting discharges from individual neurons, where the infrequent discharges are difficult to separate from dominant background noise. It may also prove useful in other applications that need to detect infrequent lowlevel audio signals against a noisy background. The audio input signal is buffered by op amp IC1 before being applied to the opposing inputs of compara- tors IC4 & IC5. Positive and negative offset voltages are generated by VR1 and IC2 and fed to the other two inputs of the comparators. Essentially, the comparators act to produce a negative voltage at their commoned outputs (C) whenever the audio signal exceeds either the positive or negative offset voltage. The signal at “C” is inverted by transistor Q1 to produce “D”. These two signals are used to control a pair of CMOS switches (S1 & S2), which either pass the audio signal to the output or short it to ground. The signal from the CMOS switches is buffered by IC3, which in conjunction with the 10kW resistor and 10nF capacitor filters out the switching artefacts. In practice, the offset voltage is adjusted until there is little or no breakthrough of the noise background at the output. Thereafter, only audio signals exceeding the threshold are passed. Inevitably, this produces some crossover distortion but this is of little consequence compared with the benefit of the quiet background. Graham Jackman, via email. ($40) The circuit at left (duplicated nine times) uses a couple of SCRs to drive each tricolour LED. These LEDs & the pushbutton switches are mounted on the front panel as shown in the diagram above. siliconchip.com.au August 2005  71 Circuit Notebook – Continued Cheap pump controller This simple but effective circuit can be used to control water level in a container. The prototype is used to pump water out of a bucket that collects condensation from a home air-conditioning system. The design is based around a 555 timer (IC1). Although the timer in configured as a monostable, it lacks the usual timing capacitor from pin 6 to ground. Instead, a metal probe inserted in the water provides a current path to a second, grounded probe. When the water level in the container reaches a third (“high”) probe, the trigger input (pin 3) is pulled low, switching the 555 output high and energising the relay via transistor Q1. Once the water level drops below the “low” probe, the threshold input (pin 6) swings high, switching the output (pin 3) low and the relay and pump off. The two 100kW pull-up resistors can be replaced with larger values if more sensitivity is required (eg, if the 555 doesn’t trigger). A switch (S1) can be included to bypass the relay for manual emptying. The “low” probe should be positioned so that the pump doesn’t run dry. The high level probe is placed at the level that you want the pump to start. Since the water is held at ground potential, you must use stainless steel or copper wire to slow corrosion. With water fountain pumps available for less than $10, this circuit offers a cheap alternative for those who have an air-conditioner on an internal wall and don’t want to be continually emptying the bucket on humid days. Adrian Hudson, Calamvale, Qld. ($35) The Latest From SILICON CHIP Completely NEW projects – the result of two years research & development • • • • 160 PAGES 23 CHAPTE RS From the publishers of Learn how engine management systems work Build projects to control nitrous, fuel injection and turbo boost systems Switch devices on and off on the basis of signal frequency, temperature and voltage Build test instruments to check fuel injector duty cycle, fuel mixture and brake and coolant temperatures Mail order prices: Aust. $A22.50 (incl. GST & P&P); Overseas $A26.00 via airmail. 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. 72  Silicon Chip Intelligent turbo timer I SBN 095852294 - 4 9 780958 522946 $19.80 (inc GST) NZ $22.00 (inc GST) TURBO BOOST & nitrous fuel controllers How engine management works siliconchip.com.au DC-DC converter powers USB Older laptop computers without built-in USB ports can be retrofitted with card-based (PCMCIA) USB ports, where needed. These cards generally require a separate 5V supply for the USB and this can be conveniently supplied using four “AA” NiCd or NiMH cells. The nominal 4.8V output is a little shy of the specified 5V but in most cases, this should not be a problem. However, the use of rechargeables does mean having to carry an extra charger in your kit. To allow the use of alkaline cells and therefore eliminate the need for the charger, the “3V to 9V DC-DC Converter” project (SILICON CHIP, March 2004) can be pressed into service. With a little trimming, the converter PC board will fit neatly into the space of two “AA” cells in a 4-cell battery holder. The accompanying diagram gives the trimming details for each end of the board, as well as the modified component overlay. The modifications involve deleting two diodes (D1 & D2), the 270W resistor (R4) and a 100mF capacitor, and relocating three capacitors. The 100nF output filter capacitor must be moved down below the trim line, and the 220mF and 470mF capacitors removed and replaced with smaller 10V units. Use lowESR capacitors for the replacements (eg, Jaycar RE-6300 & RE-6302) and mount them horizontally rather than vertically. Note that several new holes will need to be drilled, including two for the 5V output leads. The battery holder is modified by removing the cell separator furthest from the switch and the unneeded battery contacts. The single battery contact with the red wire is then relocated to provide the positive contact for the batteries. A couple of plastic nuts can be glued siliconchip.com.au Barry H is this m ubble o winner nth’s o Peak At f the las LCR Meter This diagram shows how to modify the existing DC-DC Converter board, so that it will fit in the battery holder. underneath the board to act as stand-offs. The board can be held in place with a small piece of foam sandwiched between the board and the lid. Alternatively, use a couple of blobs of hot-melt glue. The major parts required are the DC-DC Converter kit (stocked by most kit suppliers), a switched battery holder (Jaycar PH-9282) and a DC plug for the USB card. The above idea would also prove useful in PICAXE and similar lowpower microcontroller applications where a portable, regulated +5V supply is needed. Barry Hubble, Moulden, NT. CONTRIBUTE AND WIN! As you can see, we pay good money for each of the “Circuit Notebook” contributions published in SILICON CHIP. But now there’s an even better reason to send in your circuit idea: each month, the best contribution published will win a superb Peak Atlas LCR Meter valued at $195.00. So don’t keep that brilliant circuit secret any more: send it to SILICON CHIP and you could be a winner! Silicon Chip Binders REAL VALUE AT $12.95 PLUS P & P H SILICON CHIP logo printed in gold-coloured lettering on spine & cover H Buy five and get them postage free! Price: $A12.95 plus $A7.00 p&p per oder. Available only in Australia. Just fill in the handy order form in this issue; or fax (02) 9979 6503; or ring (02) 9979 5644 & quote your credit card number. August 2005  73 SERIAL LCD DRIVER for PCs, PICs, PICAXEs, Stamps . . . We detest the oft-used buzz words “human interface” but that is just what this project is: an interface between a 2400 baud serial line (inverted or non-inverted) from a PC, PICAXE or other processor and common character-type LCD displays which use the HD44780 interface. Design by Graeme Matthewson . . . Article by Ross Tester W hile there is nothing particularly new or innovative about this design, it has two huge advantages over anything similar that is currently available: (a) it is very simple; and (b) it is very cheap. In fact, it is much cheaper than anything that does the same or similar job and provides a very low cost way to turn serial data into words. You can use a variety of LCD displays, with provision on the PC board for the most common types. Features include variable backlight intensity (software controlled), two auxiliary digital outputs and a “beep” output to drive a piezo speaker. The photo above shows the interface 74  Silicon Chip (highlighted, centre) driving a typical LCD display (in this case a DL-6 from Oatley Electronics) from a lashed-together battery voltage monitor driven by a PICAXE 08M. It’s nothing special but gives just one of many practical uses for this project. TTL interface The serial interface is at TTL levels – that is, the idle state, is at TTL logic one, or near +5VDC. Therefore you can interface directly with any project offering TTL level outputs. You can also interface with PICAXE projects, using the “SEROUT” com- mand with the T2400 (ie, 2400 baud) specifier. Backlight control The backlight current is controlled by an on-board transistor. You have the choice of two resistors to set the maximum current – 4.7W for 5V operation or 39W for 12V. Display contrast is set by two fixed value resistors, 4.7kW and 330W, which provide a nominal 0.3V DC for contrast. However, you may wish to change these values to achieve different contrast levels. The serial LCD interface has a 64-byte receive buffer and the ability to interface with a variety of LCD geometries, siliconchip.com.au EEPROM storage of the LCD geometry setup, eight user-defined characters, tab size and cursor style plus a rich plain language instruction set. A supply of 5V DC with a minimum 10mA is required for this circuit. If the backlight is used, the supply current needs to be increased accordingly. The Oatley Electronics kit includes a PC board, a programmed PIC16F628 or similar PIC IC, onboard components and input/output connectors. Note that the kit does not include an LCD because of the wide variety available and the individual uses to which this project will be put. Oatley themselves have a variety of LCDs available – more information is available from their website (www. oatleye.com). Finally, a warning: the PIC processor is code-protected and the source code is not provided. Any attempt to read the chip’s code will erase the program in the chip and render it unusable! Assembly The project is very simple to construct with just one IC, a crystal, two transistors and a sprinkling of other small components. +5V REGULATED We’ve published this picture significantly larger-than-life to show how the board can be snapped off between the two sockets, if required. Start with those small components – resistors, a capacitor, diode and the transistors. The only components where you need to worry about polarity are the diode and transistors. +5V 100nF 14 Vdd 4.7k 4 RESET 2 MCLR RB6 12 4 4.7k Vdd RS LCD MODULE 8 TEST 10 AUX OUT 4 11 AUX OUT 5 SPEAKER 330Ω 6 RB7 RA3 RB4 IC1 SERIAL DATA IN 4.7k B K D1 1N4148 RA1 RA0 RB0 RB3 R/W 5 2 R1 4.7Ω 1 BACKLIGHT SUPPLY 18 Q2 C8050 17 330Ω 9 B C OSC2 Rx E OSC1 Vss 5 15 16 RES1 4MHz R1 = 4.7 Ω FOR 5V. 39 Ω FOR 12V C8050 1N4148 2005 330Ω KBL ABL 16 15 A SC  3 E 7 C RA2 RB5 LCD108 CONTRAST EN D7 D6 D5 D4 D3 D2 D1 D0 GND 1 14 13 12 11 10 9 8 7 4.7k Q1 C8050 6 13 RB2 +5V INVERTED SERIAL DATA IN Note that all resistors and the diode are mounted vertically on the PC board, as shown in both the diagram and photos. Mount the components right down on the PC board to mini- SERIAL LCD DRIVER A B K C E The IC does all the translation from serial data to display it on a variety of LCD readouts. Both inverted and noninverted data can be inputted, making it a very versatile device indeed! siliconchip.com.au August 2005  75 . 1 4.7k 4.7k 330Ω 4.7k 4.7Ω RES1 D1 4.7k 100nF IC1 LCD108 Q2 C8050 330Ω 1 . 330Ω SNAP OFF HERE IF NOT USED 2 1 16 15 16 Q1 C8050 . . mise the chances of shorting to the back of the LCD board (assuming that’s where it will be mounted). In fact, it would be a good idea to place a sheet of insulating material between the serial interface PC board and your LCD to avoid mishaps. There are two wire links on the PC board, both clearly marked on the screen-printed overlay. You should be able to make both of these from cut-off resistor leads Now you can solder in the IC socket – its notch is oriented the same way as the symbol on the PC board – but don’t insert the IC yet. Leave that until last. Solder in the input socket – be very careful as the spacing doesn’t leave much scope for poor soldering. The input socket is a right-angle mounting type, meaning the input lead will depart from the board in the same plane. Similarly, solder in the LCD connector sockets – both are included in the kit (to suit 14 or 16-pin LCDs) and even if you never use one, having BACKLIGHT SUPPLY IN REGULATED +5V IN RESET SPEAKER INV SERIAL DATA IN GROUND SERIAL DATA IN AUX OUTPUT 4 AUX OUTPUT 5 TEST Here’s the component overlay with a samesize photo alongside for comparison. As you can see, provision is made to snap the board off at the long socket if you don’t plan on using the double-row socket. both on the board makes the project that much more versatile for those who might want to swap LCD types at a later stage. However, if you will definitely only use the 16-pin (in-line) socket and would like to make the board a tad smaller, you can ignore the 14-pin (dual row) socket and snap the board off where marked, adjacent to the inline socket. Note that no provision for mounting holes is made on the PC board – it is envisaged that the board would be more-or-less used “in line”, or mounted on the back of the 40 x 2 display, as shown overleaf. If you need mounting holes and do not need the 14-pin socket, we suggest you drill a couple of holes in the corner of the PC board above and below where that socket would go, taking care to remove any copper around the edges of the holes. This is easily done by hand-twisting a (say) 5mm drill bit in the hole on the copper side of the board. Its edges act like a blade, removing any copper from around the hole sides. PC board connections “B” Backlight power supply connection. Can be linked to the +5V connection or powered from an external supply (eg, 9V or 12V DC etc). The kit is supplied with a 4.7W resistor for 5V use. For 12Vdc use a 39W. “+5” The 5V DC input. This needs to be a clean regulated supply at around 10mA; more if you power the backlight from the 5V DC (the current required will depend on your backlight). “R” The RESET connection. It has a 4.7kW pullup resistor to 5V. When the input is pulled to GND momentarily it will reset the chip and display. Parts List – Serial LCD Driver 1 PC board, code K221, 45 x 40mm 1 10-way IDC connector, right-angle PC-mount 1 16-way (or 4 x 4-way) PC-mount header socket strip 1 16-way (2 x 8-way) PC-mount female socket strip 1 18-pin DIL IC socket 1 LCD module to suit (see text) Semiconductors 1 pre-programmed PIC microcontroller (labelled LCD108) (IC1) 2 C8050 general purpose NPN transistors (Q1,Q2) 1 1N4148 diode (D1) 1 4MHz ceramic resonator Here are just two of the range of liquid crystal displays (LCDs) which can be used with this driver. Both are from Oatley Electronics – at top is the 16 x 2 DL6 which sells for $12.00, while the lower one is a DL13, a 40 x 2 display which sells for $25.00. 76  Silicon Chip Capacitors 1 100nF MKT polyester Resistors (0.25W 1%) 4 4.7kW 3 330W 1 4.7W siliconchip.com.au Connecting an Oatley DL6 display 1 Some LCDs use pins 15 and 16 to connect to their backlights. The PC board provides these connections. Other LCDs use two connections at one end of the display and will need to be connected to the PC board with some additional wire. The wiring shown in (a) is the minimum required to operate the Oatley Electronics DL6 display. The backlight of the DL6 is directly connected to +5V and GND and is on permanently. The DL6 also has some additional features; eg, a pushbutton microswitch, a bicolour LED and a piezo speaker. The extra connections shown in (b) as dark wires allow the use of the additional features of the DL6 display. With this configuration, the display will momentarily go into test mode when the switch is pressed. If digital output #4 is addressed, the LED will glow red. If digital output #5 is addressed, the LED will glow green. The piezo speaker will also beep when addressed. For details on addressing inputs and outputs, see the programming section of these notes. “SP” The speaker output. The chip outputs a short burst (“BEEP”) which can be connected to a peizo speaker “D” An input designed to take inverted serial data from an RS232 port (eg, a PC etc). “–” The GND or 0V connection. “D” An input designed to take noninverted, logic-level serial data from a micro such as a PICAXE, PIC or BASIC STAMP etc. “#4” and “#5” Digital outputs which can be used to switch other devices or an indicator LED, etc. “T” The TEST input. Holding this to GND while rebooting the processor will show the test siliconchip.com.au (a) 1 1 (b) display on your LCD. No pullup resistor is required. Configuration commands. Warning: Do not include configuration commands in software loops. Although the EEPROM can be written many hundreds of thousands of times, in a software loop the life of the EEPROM could be used up very quickly. It is best to not use configuration commands in your final software. Note: Commands are case sensitive. A number of parameters are stored in the processor, including the geometry of the LCD, the type of cursor, the number of spaces in a tab and the eight user-defined characters. The settings of all of these are displayed briefly on the LCD when the processor boots. The default is a 20 x 4 LCD, a tab size of 4, a full blinking cursor (3) and 1 the eight special user-defined characters. All of these parameters may be modified. Note that when the modifications are made, the new values are written to the processor’s EEPROM. Thus, the userdefined characters and the geometry of the LCD need only be modified once. Set LCD geometry Setting the geometry (size) defines the configuration of the interfacing LCD. ?Gyxx “?G216” will set the LCD to 2X16 configuration. Valid entries – some include ?G216 (2X16),?G220 (2X20),?G224 (2X24),?G240 (2X40), ?G416 (4X16) and ?G420 (4X20). The configuration is important for the processor to properly position the cursor after each text character is (Continued on P80) August 2005  77 78  Silicon Chip siliconchip.com.au ‘ Be sure Tx Pin is idle for some time ‘ wait for PICAXE LCD to boot ‘ configure LCD as 4 X 20 ‘ clear the LCD and home the cursor SerOut 0, T2400, (“?G420”) SerOut 0, T2400, (“?f”) ‘ Variables used in PWMDemo ‘These variables are used in Sub SerOutByteHex ‘These variables are used in Sub BarDemo High 0 Pause 5000 Symbol Duty = B9 Symbol NN = B8 Symbol LeftOver = B9 Symbol Num_5 = B10 Symbol J = B11 Symbol X = B8 Symbol N = B2 Symbol OWord = W0 Symbol OByte = B3 ‘ ‘ Configures the interfacing LCD for 4X20 geometry. ‘ This need only be done one time as this is saved in the K221 EEPROM ‘ ‘ Clears the LCD using the “?f” command. ‘ Writes some text. Note the new line function “?n” ‘ Displays the user defined characters using commands ?0, ?1, etc ‘ Moves cursor to line 1, col 00 using commands “?y1” and “?x00” ‘ Clears lines 1, 2 and 3 using “?l” command. ‘ Note “?j” is used for down cursor. ‘ ‘ Positions cursor at line 1 and displays the values of N and Word in ‘ decimal and in Hexadecimal. ‘ ‘ Defines new user defined characters consisting of no vertical lines, ‘ 1 vertical line, etc through 5 vertical lines. ‘ ‘ A bar scaled to 0 through 25 is displayed on line 3. ‘ This might be used to graphically display a quantity. ‘ ‘ The PWM duty cycle is then set to 25 steps over the range of ‘ 00 to 250 using the ?B command. ‘ The duty cycle is also displayed on the LCD. ‘ ‘ The program then continually sets the two general purpose outs to ‘ 10 and 01 using the ?H and ?L commands. ‘ ‘ Written by.... Peter H Anderson, Baltimore, MD, Feb, ‘04 LeftOver = LeftOver + 48 SerOut 0, T2400, (“?”, LeftOver) For N = 0 to 25 SerOut 0, T2400, (“?y3?x00?l”) NN = 4 * N NN = 100 - NN Num_5 = NN / 5 LeftOver = NN % 5 For J = 1 to Num_5 SerOut 0, T2400, (“?5”) Next For N = 0 to 25 SerOut 0, T2400, (“?y3?x00”) NN = 4 * N Num_5 = NN / 5 LeftOver = NN % 5 For J = 1 to Num_5 SerOut 0, T2400, (“?5”) Next LeftOver = LeftOver + 48 SerOut 0, T2400, (“?”, LeftOver) Next BarDemo: AGAIN: SerOut 0, T2400, (“?H5?L4”) SerOut 0, T2400, (“.”) Pause 500 SerOut 0, T2400, (“?L5?H4”) SerOut 0, T2400, (“!”) Pause 500 GoTo AGAIN Pause 200 GoSub PWMDemo Pause 200 ‘ convert to a character ‘ decreasing bar ‘ convert to a character ‘ increasing bar ‘ continually bring outputs 5 & 4 hi and lo ‘ cursor to beginning of line 3 and clear line SerOut 0, T2400, (“?y3?x00?l”) GoSub BarDemo ‘no cursor SerOut 0, T2400, (“?c0”) Pause 200 SER_LCD.Bas – Illustrates many capabilities of the Serial LCD Interface (written for the PICAXE 18X) siliconchip.com.au August 2005  79 PICAXE LCD?n”) ‘ position cursor at beginning of row 1 ‘ clear lines 1, 2 and 3 and start at line 1 ‘ note the use of down cursor command SerOut 0, T2400, (“?y1?x00”) SerOut 0, T2400, (“?l?j?l?j?l?y1”) OWord = 12345 ‘ display a word in decimal ‘ and in hex SerOut 0, T2400, (#OWord, “?t”) GoSub SerOutWordHex SerOut 0, T2400, (“?n”) ‘ define special characters ‘ delay to allow EEPROM to program SerOut 0, T2400, (“?D00000000000000000”) Pause 200 SerOut 0, T2400, (“?D51f1f1f1f1f1f1f1f”) SerOut 0, T2400, (“?D41e1e1e1e1e1e1e1e”) Pause 200 SerOut 0, T2400, (“?D31c1c1c1c1c1c1c1c”) Pause 200 SerOut 0, T2400, (“?D21818181818181818”) Pause 200 SerOut 0, T2400, (“?D11010101010101010”) Pause 200 ‘ beep SerOut 0, T2400, (“?g”) Pause 1000 Next OWord = OWord + 1 ‘ display in hex ‘ display in decimal OByte = N GoSub SerOutByteHex SerOut 0, T2400, (“?t”) SerOut 0, T2400, (#N) SerOut 0, T2400, (“?t”) ‘ locate cursor to beginning of line 1 ‘ pause to admire Pause 2000 For N = 0 to 25 SerOut 0, T2400, (“?x00?y1”) ‘ display special characters ‘ note new line SerOut 0, T2400, (“?0?1?2?3?4?5?6?7?n”) SerOut 0, T2400, (“www.phanderson.com?n”) Pause 100 SerOut 0, T2400, ( “ Return OByte = OWord / 256 GoSub SerOutByteHex OByte = OWord % 256 GoSub SerOutByteHex SerOutWordHex: Return SerOutByteHex_2: SerOut 0, T2400, (X) If X <= 57 Then SerOutByteHex_2 X=X+7 X = Obyte % 16 X = X + 48 SerOutByteHex_1: SerOut 0, T2400, (X) If X <= 57 Then SerOutByteHex_1 X=X+7 SerOutByteHex: X = OByte / 16 X = X + 48 Return SerOut 0, T2400, (“?f”) SerOut 0, T2400, (“?B00”) SerOut 0, T2400, (“?B”) GoSub SeroutByteHex Pause 200 Next ‘ it is alphabetic; A, B, C, D, E, F ‘ low nibble ‘ add the character ‘0’ ‘ it is alphabetic; A, B, C, D, E, F ‘ high nibble ‘ add the character ‘0’ ‘ clear the LCD ‘ set PWM to 0 ‘ backlight control PWMDemo: SerOut 0, T2400, (“?f”) ‘ clear the LCD SerOut 0, T2400, (“ PWM Duty Demo?n”) For N = 0 to 25 Duty = 10 * N SerOut 0, T2400, (“?l”) OByte = Duty GoSub SerOutByteHex ‘ display the PWM in hex Return Next Connecting an Oatley DL13 display 11 The biggest advantage of this display (apart from the extra characters, of course) is that it can plug directly onto the driver board via the outer (double row) socket. Therefore it doesn’t need any cabling – all you have to do is make sure you get it the right way around. The photo at right shows the correct position. Some LCDs have a dual row of seven or eight pins at one end while others have a single row of 14 or 16 pins along one edge. The driver described here will plug Single row type connection directly on to either type of display, as shown below. 11 1 Single row type connection Dual row type connection displayed and in executing such commands as backspace, up cursor, down cursor, new line, etc. Cursor style settings The style of the cursor may be set using the ?c command. “?c3” where the number is in the range of 0-3. Valid entries; 0, 2, 3. 0 configures as no cursor. 2 configures the cursor as nonblinking. 3 configures the cursor as blinking. As with the set geometry and set tab, the style of the cursor is saved to the EEPROM. Setting tabs The tab size may be adjusted; “?sx” – Valid entries; 1 - 8. “?s5” will set the tab size to 5 characters wide. When this command is received by the processor, the new tab size is written to EEPROM and this value is used thereafter when executing the ?t command. With the ?t command, the cursor is advanced, and characters in its path are overwritten with a space. ?h – Backspace ?i – Forward cursor ?j – Up cursor ?k – Down cursor ?l – Clear current line and leave cursor at the beginning of the line Backlight intensity ?m – Position the cursor at the beginThe intensity of a LED backlight on Dualning current line. row of typethe connection the associated LCD may be adjusted; ?n – Advance to the beginning of the “?B80” Valid entries; 00 - ff next line and clear current line. Note that the digits following the ?t – Advance the cursor one tab. “B” are 2-digit hexadecimal (00= off, ?? – Display the character ‘?’. ff= full on). The cursor may be set to any poThe output is used to switch the sition using the x and y commands duty cycle of a transistor which con- below; trols the average backlight current. ?y0 ?x15 LCD commands. Note that the line number follows A partial list of various commands the ‘y’ command and the column numfollows. Note that all commands are ber, consisting of two digits, follows prefaced with a “?” and the commands the ‘x’ command. are case sensitive. Thus, outputting the string ?a – Set cursor to home position. “?y1?x10Hello?n” positions the cursor ?b – Destructive backspace (removes at column 10 of line 1 and then prints character) “Hello”, followed by a new line which ?f – Clear LCD and leave cursor in the also clears the next line. home position Note that the line and column ?g – Beep, outputs a 50ms burst of numbers begins with 0. Thus, for a 4 around 500Hz on the “B” connection x 20 LCD, valid lines are 0 - 3 & valid on the driver board. columns are 00 - 19. For example, if the cursor is in column 3 and the tab size is 5, the cursor will advance to column 5. Anything in columns 3 and 4 will be replaced with spaces. 1 Resistor Colour Codes 1 1 1 No. 1 1 1 Value 4.7kW 330W 4.7W 80  Silicon Chip 4-Band Code (1%) yellow violet red brown orange orange brown brown yellow violet gold brown 5-Band Code (1%) yellow violet black brown brown orange orange black black brown yellow violet black silver brown User-defined characters User-defined characters may be entered using the ?D command: “?D300000000001f1f1f” The first number after the ‘D’ is the location where your user-defined character is stored in the EEPROM, In this siliconchip.com.au case user-defined character 3. This is then followed by the eight data bytes expressed in two-digit hexadecimal. Note that the hexadecimal letters must be lower case. In this example, lines 0, 1, 2, 3 and 4 consist of no pixels and lines 5, 6 and 7 consist of all five pixels. Thus, when user-defined character 3 is displayed using the command ?3, a character consisting of the lower three lines will be displayed. D3 00 00 00 00 1f 1f 1f location OOOOO OOOOO OOOOO OOOOO ###### ###### ###### Any of eight user defined characters may be displayed using the digits 0 - 7. Thus, “?5?2” causes user-defined character 5 followed by user character 2 to be displayed on the LCD. Each user-defined character is saved in EEPROM. This kit provides a 64-byte serial receive buffer. However, be careful. If you are defining all eight user defined characters, this involves sending 19 * 8 or 152 characters. Writing each of the eight bytes to EEPROM requires 15ms or more and thus, one can easily over run the buffer. Rather, provide a 1-second delay after defining each character. Direct control of the LCD. Commands may be directly passed to the LCD using the ?! command; “?!01” sends the 01command directly to the LCD which clears the LCD. Caution With all other commands the pro- gram keeps track of the current cursor position. This is not done with commands sent directly to the LCD using the ?! command. Thus, if the user configures the LCD such that the cursor is located at some point, subsequent line feeds and similar will not work correctly as the program does not know the current cursor location. Clearly, if the ?! command is used to place the LCD in a mode such that the cursor is decremented with each character or the display itself is scrolled, the subsequent operation of the LCD which assumes an incrementing cursor and a fixed display will give unpredictable results. GP auxillary outputs The K221 kit provides two general purpose TTL outputs. Either of these outputs, 4 and 5, may be brought high or low using the ‘H’ and ‘L’ commands. “?H4?L5” brings output 4 high and output 5 low. Valid entries, 4 or 5. On power up, all outputs are at a high impedance (configured as inputs). As each output is addressed, it is taken out of the high impedance state. The initial high impedance state permits the user to use either pull-up or pull-down resistors to avoid “bounce” when the processor is powered. The current (source or sink) by any output should be limited to a maximum of 15mA. One important point: normally, when idle the serial terminal is at a logic one. When a character is sent, the lead is brought low for 1/2400 secs (start bit) followed by the data bits. However, when the PICAXE is booted, the output is initially at a high impedance and is then brought to an output logic zero. Thus, prior to executing the first SerOut instruction, it is important to bring the output to a logic one and pause briefly. SC Where from, how much? This project was designed by Oatley Electronics who hold the copyright on the circuit and PC board design. A complete kit of parts, (Cat K221) which includes the PC board and all on-board components (but NOT an LCD) is available from Oatley for $20.00. As a special offer to SILICON CHIP readers, Oatley will include a DL6 backlit LCD (16x2), normally selling for $12.00, for $10.00 extra. Contact Oatley Electronics on (02) 9584 3563 or via their website: www.oatleye.com siliconchip.com.au Select your microcontroller kit and get started... From $295* RCM3400 Fax a copy of this ad and receive a 5% discount on your order! Feature rich, compiler, editor & debugger with royalty free TCP/IP stack • Prices exclude GST and delivery charges. Tel: + 61 2 9906 6988 Fax: + 61 2 9906 7145 www.dominion.net.au 4007 Ozitronics www.ozitronics.com Tel: (03) 9434 3806 Fax: (03) 9011 6220 Email: sales2005<at>ozitronics.com Rolling Code 2-channel UHF Remote Momentary or latching relays with indicator LEDs. Range up to 25m. Up to 15 Tx's can be learnt by one Rx. 12VDC. K157 - $71.50 Also available assembled K157A...... $88.00 4-Channel version (kit) K180 ...............$82.50 10-Channel version (kit) K181 .............$99.00 2-button remote for K157 .................$23.10 4-button remote for K180/1 ..............$25.85 Prices include GST – shipping extra. Full documentation available from website. Silicon Chip Binders REAL VALUE AT $12.95 PLUS P & P H SILICON CHIP logo printed in gold-coloured lettering on spine & cover H Buy five and get them postage free! Price: $A12.95 plus $A7.00 p&p per oder. Available only in Australia. Just fill in the handy order form in this issue; or fax (02) 9979 6503; or ring (02) 9979 5644 & quote your credit card number. August 2005  81 Enhanced Sports Scoreboard Here’s an upgraded version of the Professional Sports Scoreboard described earlier this year. In particular, it now provides a 2-digit “Fouls” display for each team, as well as the original displays for the Home and Away scores, Time Remaining and Current Period. 82  Silicon Chip By JIM ROWE I F YOU READ the articles in our March-May 2005 issues on the Jaycar Sports Scoreboard project, you’ll know that even before we finished describing it, we were prompted to add netball scoring to its original basketball code capabilities. That was done simply by upgrading the controller firmware, so it would set the board up siliconchip.com.au siliconchip.com.au August 2005  83 Fig.1: this is the revised scoreboard controller circuit. The main change involves the added 16-way ribbon cable connector (CON4) for the Fouls displays. This connects to four previously spare outputs on digit decoders IC2 and IC3, to provide the drive signals for the four extra digits. Fig.2: the Scoreboard Display 2 (Home/Away Fouls) board is driven via CON4 on the controller board and uses 56 10mm yellow LEDs to form two complete 7-segment digits. for netball in response to an extra setup code from the console (ie, no changes were required to the hardware of either the scoreboard or the console). Subsequently, as soon as the third article had been published, we started to get requests for even more features. 84  Silicon Chip The most common of these requests was for the addition of basketball “Fouls” displays – one for each of the two teams (and preferably each display having two digits for a count of 0-99). In the end, it became clear that we were going to have to upgrade the design to add this feature at the very least. While we were at it, we decided to make a few other changes as well. In particular, the display brightness has been improved, while the firmware has been upgraded to provide improved timing accuracy. The wireless Consiliconchip.com.au trol Console is virtually unchanged, though – only the front panel art has been changed, to re-label keys that have changed in function. This means that if you have an existing control console, it can be used as is. Adding the fouls displays Unfortunately, the two extra fouls displays couldn’t be added to the original design by simply making a few changes to the firmware. There were some unused outputs available from the digit decoder ICs but no spare conductors in the original ribbon cable linking the display boards to the controller board, to drive any additional displays. The only real option was to modify the controller board and add a connector for a second ribbon cable, to drive the two additional display boards. It was quite a challenge to fit this extra cable connector (a 16-way DIL socket) plus its segment drive resistors and other circuitry but, in the end, this was done without changing the overall size of the board. Of course, it was also necessary to come up with an additional display board design, for the new Fouls displays. This was adapted from the original team score board design, with the same system of allowing it to be made in two versions (Home Fouls and Away Fouls) simply by fitting the digit drive input resistors in two different positions. The new Fouls display boards provide two 130mm-high digits (like the other displays), each formed using 28 10mm-diameter yellow LEDs. This was done so that they could be added to the original Scoreboard with as little complication as possible. The new displays mount behind additional cutouts at the lower corners of the board, below the team score displays. Note that this can be done even with existing boards, as the “end of period” siren is moved over to a position midway between the Game Period and Away Fouls displays. While the controller board was being modified to drive the additional display boards, we also took the opportunity to make a few other modifications which enhance performance. For example, the power supply circuitry has been changed so that the Scoreboard can now be powered from a regulated 15V plugpack, for even siliconchip.com.au Par t s Lis t – Sports Scoreboard Additional Cables & Sockets 3 16-way IDC line sockets (Jaycar PS-0985) 1 900mm length of 16-way IDC ribbon cable Revised Controller Board 1 PC board, code BSBCONTE, 127 x 190mm 1 2.4GHz AV Receiver module, AWM608RX (Jaycar QC3592) 1 31mm length of 1mm-dia brass wire 1 TO-220 heatsink, 6021 type 1 4-way DIP switch (S1) 1 10MHz crystal (X1) 1 PC-mount 26-way DIL socket (CON1) 1 PC-mount 16-way DIL socket (CON4) 1 PC-mount 2.5mm concentric DC socket (CON2) 1 2-way PC-mount terminal block (CON3) 1 18-pin DIL IC socket, machine pins 13 M3 x 6mm machine screws, round head 4 M3 x 25mm tapped metal spacers 4 M3 x 15mm machine screws, csk head 9 M3 nuts and star lockwashers 1 15V DC 1.5A regulated plugpack supply (Jaycar MP-3423) 1 length of 0.5mm tinned copper wire for links Semiconductors 1 PIC16F84A-20P microcontroller programmed with SCORDISP2.HEX (IC1) 2 4028B CMOS decoders (IC2, IC3) 1 74HC08 quad NAND gate (IC4) 1 74HC74 dual D-type flipflop (IC5) 4 PN100 NPN transistors (Q1,Q9, Q10,Q12) higher display brightness. In addition, the board earthing has been modified to reduce the risk of interference to the PIC controller (IC1) and the digit decoders (IC2, IC3), due to the high current pulses through display segment driver transistors Q2-Q8. 8 MTP3055 power MOSFETs (Q2-Q8,Q13) 1 PN200 PNP transistor (Q11) 1 7805 +5V regulator (REG1) 1 5mm red LED (LED1) 6 1N4004 1A diodes (D1-D6) 4 1N4148 signal diodes (D7-D10) Capacitors 1 2200mF 16V RB electrolytic 1 100mF 16V RB electrolytic 2 10mF 16V tantalum 3 4.7mF 16V tantalum 5 100nF multilayer monolithic 1 100nF MKT metallised polyester 2 33pF NPO disc ceramic Resistors (0.25W 1%) 1 100kW 1 4.7kW 2 47kW 1 470W 1 22kW 8 47W 6 10kW 14 10W Fouls Display Board (x 2) 1 PC board, code BSB-D2, 180 x 190mm 1 PC-mount 16-way DIL socket (CON1) 8 6mm x M3 machine screw, round head 6 25mm x M3 tapped metal spacer 6 15mm x M3 machine screw, csk head 2 M3 nuts and star lockwashers 1 length of 0.5mm tinned copper wire for links Semiconductors 2 PN100 NPN transistors (Q1,Q2) 2 BD136 PNP transistors (Q3,Q4) 56 yellow 10mm LEDs, high brightness or standard Capacitors 1 1000mF 16V RB electrolytic Resistors (0.25W 1%) 4 4.7kW 2 120W Naturally, the scoreboard controller firmware also had to be extensively revised in order to drive the additional Fouls displays and to allow them to be updated (incremented or decremented) from the Control Console. Finally, we also took the opportunity August 2005  85 Console. This was achieved by simply re-allocating the original “+3” and “+2” score buttons for each team, so that they now perform the “Fouls +1” and “Fouls -1” functions. In practice, they still send the original control codes to the scoreboard controller but the latter now interprets them to carry out the new functions. As a result, the only modification that has been made to the Control Console is a change in the front panel artwork, to show the new button functions. This change in the console button functions does mean that in order to add two or three points to the score of either team, you now have to press their ‘Score +1’ button two or three times in succession rather than simply pressing the original ‘+2’ or ‘+3’ buttons once. However we believe users won’t mind having to make a few more button presses, in order to have the added Fouls facility with a minimum of cost and complexity. Circuit details Fig.3: this is the parts layout for the revised controller board. Make sure that all polarised parts go in the right way around. to improve the controller’s timing accuracy by making the timing function independent of the number of console commands that have to be processed. This now gives the scoreboard a timing accuracy of better than 0.04% and also provides a spin off benefit: there is now virtually no display blinking when the 86  Silicon Chip controller is processing commands from the console. Control console As mentioned above, all these enhancements have been made without making any changes to the circuitry or firmware in the wireless Control Fig.1 shows the revised scoreboard controller circuit. As shown, the additional 16-way ribbon cable connector for the Fouls displays is CON4 and this is located just to the right of the original 26-way display connector (CON1). It connects to four previously spare outputs on digit decoders IC2 and IC3, to provide the drive signals for the four extra digits. These are digits D13 and D14 on the Home Fouls board and D15 and D16 on the Away Fouls board. The new display boards also need the 7-segment drive lines and these are derived from segment driver transistors Q2-Q8 via a second set of 10W current limiting resistors. The only other connections needed are for 14.4V power and ground. These both use multiple ribbon conductors to improve current carrying capacity and to also provide a measure of shielding. The only other change to the controller circuit is the addition of three 1A power diodes (D4-D6) in series with the input to +5V regulator REG1. These drop a further 2V or so, allowing the controller to be powered from a 15V DC regulated plugpack (for improved display brightness), while preventing REG1 from overheating due to excessive voltage drop. Fig.2 shows the circuit for the new Fouls display board. It’s basically just a simplified version of the original siliconchip.com.au Team Score board circuit. However, in this case, there are only two digit drivers, using transistor pairs Q1-Q3 and Q2-Q4 respectively. When the board is used as the Home Fouls display, the two 4.7kW driver input resistors are connected to pins 9 and 7 of the 16-way DIL connector CON1, so that the digits become D13 and D14. Conversely, when the board is used as the Away Fouls display, the resistors are connected to pins 3 and 1 of the connector instead, so the digits become D15 and D16. As mentioned earlier, the digits themselves are formed using 28 x 10mm-diameter yellow LEDs, with four LEDs per display segment. Construction details Fig.3 shows the parts layout for the new controller board. All of the original components are used and most are located in either exactly the same position or moved just a short distance to make space for the added components. This board is wired in exactly the same way as the original, apart from having an additional 16-way DIL connector, a few more wire links and some extra resistors and diodes to fit. Fig.4 shows how to wire up the two new Fouls display boards. This mainly involves fitting 56 large yellow LEDs to each board. Note that these all fit with their longer anode lead towards the top of the board, so the job is easily done once you get into the swing of it. That done, you can fit the six wire links, connector (CON1), the four transistors and the resistors and capacitors. Note that the locations of the two 4.7kW resistors adjacent to CON1 vary, depending on whether you’re building the Home Fouls display or the Away Fouls display. Finally, follow Fig.5 to connect Your completed controller board should look like this. It’s now powered from a 15V DC plugpack, for even greater brightness from the LED displays. the two Fouls display boards to the controller board. This is done using a 900mm-long 16-way ribbon cable fitted with three IDC line sockets. as the original version. For example, the Scoreboard should have power applied first and then power applied to the console after about 10-20 seconds. This is necessary because when the console is powered up, it sends a code to set up the Scoreboard for the game Revised operation In most respects, the upgraded Scoreboard operates the same way Table 1: Resistor Colour Codes o o o o o o o o o o siliconchip.com.au No. 1 2 1 6 5 1 2 8 14 Value 100kW 47kW 22kW 10kW 4.7kW 470W 120W 47W 10W 4-Band Code (1%) brown black yellow brown yellow violet orange brown red red orange brown brown black orange brown yellow violet red brown yellow violet brown brown brown red brown brown yellow violet black brown brown black black brown 5-Band Code (1%) brown black black orange brown yellow violet black red brown red red black red brown brown black black red brown yellow violet black brown brown yellow violet black black brown brown red black black brown yellow violet black gold brown brown black black gold brown August 2005  87 Table 1: here’s how to set the console DIP switches for the various games. Fig.4: here’s how to build the Fouls display board. Note that two slightly different versions must be built – one with the two 4.7kW resistors at top left in the “Home Fouls” position and one with the resistors in the “Away Fouls” position. Note: PC overlay shown 64% of actual size. 88  Silicon Chip you want to play (as set by the console’s internal DIP switches). The short delay is needed to make sure that the Scoreboard controller and its 2.4GHz receiver are fully operational before the console sends the game code. The accompanying table (Table 1) shows how to set the console DIP switches for the various games. To reset the Scoreboard ready for a new game, you press the two red Reset buttons on the console simultaneously and then press them both again. This “press them both together twice” procedure is designed to prevent you from accidentally resetting the board in the middle of a game. To start a new game period, you press the green “Start Next Game Period” button. This starts the countdown clock and as the time passes, the time remaining in that period is continuously displayed at the top of the scoreboard. The Game Period display shows the current period: “1”, “2”, “3” and so on. If you subsequently press the “Start Next Game Period” button after the last normal period has ended, the Game Period display will show “E” (for extra time) and the clock will count down from 5:00 minutes (the standard extra time period duration). During any game period, if a “time out” is called, you can stop the Scoreboard’s clock by pressing the white “Stop Clock” button. Then, when play resumes, you press the Blue “Restart Clock” button to set it going again. During play, you can increment the score of either team by pressing the relevant grey “Score +1” button. To increase the score by two or three, you simply press that button two or three times (not too rapidly, or the extra points won’t be registered). If a mistake is made and the score needs to be reduced, you just press the black siliconchip.com.au Fig.5: the fouls display boards are connected to the controller board using a 16-way ribbon cable fitted with three IDC line sockets. Be sure to position the red cable edge stripe as shown. “Score -1” button for that team. Fouls are registered in exactly in the same way, except that you use the yellow “Fouls +1” or white “Fouls -1” buttons. Note that while the team scores are maintained through all of the game periods, the fouls are cleared at the start of each new game period. The only exception to this is at the start of an “Extra Time” period, where the fouls registered for the last normal game period are maintained. As before the Scoreboard’s countdown clock displays minutes and seconds during most of each game period but automatically switches over to seconds and tenths of a second during the final minute of play. Finally, at the end of this period, the siren sounds for two seconds to signal SC the end of play. siliconchip.com.au The Control Console has a new front panel label to re-assign some of the switch functions. Apart from that, it’s unchanged. August 2005  89 Salvage It! BY JULIAN EDGAR Washing machine pressure switches Want to control the water level in a tank, or detect a vehicle passing over a smalldiameter hose? You can do both these jobs and much more, using pressure switches salvaged from old washing machines. A LL OLDER WASHING machines and dishwashers use mechanical pressure switches to detect the water level inside the tub. A hose is connected from the base of the tub to the pressure switch, which measures the air pressure being applied by the column of water. The pressure at the base of a column of water 27.69 inches high is 1psi, or to put it another way, 10.2cm of water exerts a pressure of 1kPa (kilopascals). So, as you can imagine, a switch that’s designed to detect when the water level in a washing machine has reached (say) a depth of 15 inches must be capable of accurately measuring pressures of just 0.5 psi (~3.5 kPa)! In other words, the pressure switches in washing machines are amongst the most sensitive that you can buy. Well, you don’t really have to buy them – these switches can be scrounged for literally nothing wherever washing machines are being discarded. Washing machine pressure switches have three main characteristics: (1) Very high sensitivity; (2) A “snap” action, to ensure sharp, decisive switching – they’re either on or off; and (3) Excellent power handling. How they work Typically, washing machine pressure switches have a large sensing diaphragm that’s about 60mm or so in diameter and three quick-connect male terminals. One connection is common, while the others are for normally open (NO) and normally closed (NC) connections. A setpoint adjustment mechanism is built in (it’s directly controlled by the “water level” knob) and the switch opens and closes with audible clicks. (Note that if the washing machine has digital controls, rather than a mechanical switch, it almost certainly uses an electronic variable pressure sensor to detect the water level. These three-wire sensors are easy to interface with but we’ll leave them for another time). Washing machine pressure switches directly control the hot and cold water inlet solenoids and so are rated for quite high currents – 15A at 240V AC is typical. So for low-voltage DC applications, the switches can certainly cope with (say) 5A. This means that, for most loads, a relay won’t be needed. Dishwashers use pressure switches that are similar to those used in washing machines. However, instead of having one switching point, they have multiple levels. A 2-position switch may switch at 10cm and 15cm of water, for example, while a 3-position switch may trip at 15cm, 25cm and 35cm of water. These switches also look a lot like washing machine pressure switches, except they have multiple electrical terminals (six or even nine) and don’t have external level adjustment. However, some have screwdriver adjustment for both the trip levels and the hysteresis. Salvaging pressure switches Washing machine and dishwasher pressure switches can be easily scrounged for nothing – you’ll find a pressure switch inside nearly every one of these appliances when they’re discarded. They are extremely sensitive and their trip points are externally adjustable. 90  Silicon Chip When extracting the pressure switch from a washing machine, be careful that you don’t also inadvertently remove the adjustment mechanism siliconchip.com.au Silicon Chip Binders REAL VALUE AT $14.95 PLUS P & P This Goyen Controls Model SRM40 washing machine pressure switch is typical and has single-pole normally open (NO) and normally closed (NC) contacts. When set to minimum pressure, it closes at about 13cm of water and opens at 4cm of water. Conversely, when set to maximum pressure, it closes at about 20cm of water and opens at 14cm of water. Its current rating is 15A at 240V AC. – it’s often part of the bracket holding the switch in place! As for identifying the pressure switch, that’s easy. Nine times out of 10, it’s directly behind the “water level” adjustment knob in the top control panel of the machine. If the machine’s upside down or partly destroyed, follow the sensing tube from the base of the wash tub. And while you’re at it, it’s also usually worth scrounging the tube, which is often a high-quality plastic hose! You never know when it might come in handy for something! By contrast, dishwasher pressure switches are normally buried beneath the stainless steel drum. Because they’re not externally adjustable, they don’t need to be located close to the control panel. Modifying pressure switches Depending on your application, you might want your salvaged pressure switch to operate at pressures that are different to its standard range. That’s not hard to do if you have a washing machine pressure switch, as they are quite easy to modify. In standard form, turning the ad- Rat It Before You Chuck It! Whenever you throw away an old TV (or VCR or washing machine or dishwasher or printer) do you always think that surely there must be some good salvageable components inside? Well, this column is for you! (And it’s also for people without a lot of dough.) Each month we’ll use bits and pieces sourced from discards, sometimes in mini-projects and other times as an ideas smorgasbord. And you can contribute as well. If you have a use for specific parts which can siliconchip.com.au easily be salvaged from goods commonly being thrown away, we’d love to hear from you. Perhaps you use the pressure switch from a washing machine to control a pump. Or maybe you have a use for the highquality bearings from VCR heads. Or perhaps you’ve found how the guts of a cassette player can be easily turned into a metal detector. (Well, we made the last one up but you get the idea . . .) If you have some practical ideas, write in and tell us! These binders will protect your copies of S ILICON CHIP. They feature heavy-board covers & are made from a dis­ tinctive 2-tone green vinyl. They hold 12 issues & will look great on your bookshelf. H 80mm internal width H SILICON CHIP logo printed in gold-coloured lettering on spine & cover H Buy five and get them postage free! Price: $A14.95 plus $A10.00 p&p per order. Available only in Aust. Silicon Chip Publications PO Box 139 Collaroy Beach 2097 Or call (02) 9939 3295; or fax (02) 9939 2648 & quote your credit card number. Use this handy form Enclosed is my cheque/money order for $________ or please debit my  Visa    Mastercard Card No: _________________________________ Card Expiry Date ____/____ Signature ________________________ Name ____________________________ Address__________________________ __________________ P/code_______ August 2005  91 Dishwasher switches have multiple contacts that switch at different pressure levels. This Eaton 78376-002 Dishwasher Level Switch has three single-pole, normally closed (NC) contacts. Level 1 closes at 18cm and opens at 8cm of water; level 2 closes at 20cm and opens at 18cm of water; and level 3 closes at 34.5cm and opens at 30.5cm of water. Its total current rating is 18A at 250V AC. justment control typically allows the trip pressure to be set to detect water depths anywhere from 9-20cm. But if you remove the adjustment bracket, you can access the internal spring which sets the sensitivity. For example, by using a very light spring (ie, one that provides just enough force to return the diaphragm to its un-triggered position when the pressure is removed), it’s possible to get a switch to trigger at just 5cm of water (~0.5kPa or 0.08psi). The external adjustment would then typically give a range of about 5-7.5cm of water but, of course, this will vary depending on the unit and the spring used. Put in a stiffer spring and the adjustment range becomes larger. And while we haven’t tried it, you could probably stop the switch from closing until you had 15-20kPa of pressure. Note, however, that the rubber diaphragm isn’t designed to withstand these pressure levels, so there may be some long-term reliability problems. Using pressure switches So what uses can be made of these switches? That depends on your Brand New From SILICON CHIP imagination but here are some suggestions: (1). Controlling an electric water pump – eg, to keep a container full of water. Just as in a washing machine, the depth of the water can be sensed from a hose connected to the base of the container. The advantage over a float switch is that the level is easily adjustable. (2). Providing a low water level warning – eg, the switch could be used to activate a buzzer or light if the liquid level in a tank drops below an adjustable point. (3). Providing water level indication – eg, by using a dishwasher pressure switch to activate LEDs or lights to indicate water level in a tank. By using two dishwasher switches and adjusting their individual setpoints appropriately, it’s easy to have six levels indicated. However, you’ll need a lot of wires to connect the switches to your display. (4). Detecting vehicle movement using a washing machine pressure switch. The switch would be triggered by air pressure when the vehicle crosses a hose. Just remember to plug the end of the hose that’s not connected to the switch! So there are four applications but there are lots more. It’s certainly worth salvaging these very sensitive SC switches! 160 PAGES 23 CHAPTE RS Mail order prices: Aust: $A22.50 (incl. GST & P&P) Overseas: $A26.00 via airmail From the publishers of Completely NEW projects – the result of two years research & development • Learn how engine management systems work • Build projects to control nitrous, fuel injection and turbo boost systems • Switch devices on and off on the basis of signal frequency, temperature and voltage • Build test instruments to check fuel injector duty cycle, fuel mixture and brake and coolant temperatures We explain the why as well as the how to! Intelligent turbo timer I SBN 095852294 - 4 9 780958 522946 $19.80 (inc GST) NZ $22.00 (inc GST) TURBO BOOST & nitrous fuel controllers How engine management works Available direct from Silicon Chip Publications, PO Box 139, Collaroy, NSW 2097. Phone (02) 9979 5644; Fax (02) 9979 6503. Email silchip<at>siliconchip.com.au or visit our website: www.siliconchip.com.au 92  Silicon Chip siliconchip.com.au ***NEW KITS*** NEW AND IMPROVED CNC (COMPUTER NUMERIC CONTROL) KITS We have re-vamped our CNC kits, K142B and K142C kits and added a new K142A kit. You can build your own CNC machine or retro-fit an existing lathe or mill. Check out our website for more details and pictures of a CNC machine built by one of our staff from surplus parts. The K142A simply plugs in to your PC or a cable to your PC, Stepper motor drives K142B and limit switches etc. can be connected to the clearly marked screw terminals. K142A also has two auxillary relays that can be turned on and off via your software to start spindle motors or dust extractors etc. K142B has a new higher speed Step and Direction input. K142C now has adjustable current limiting via a single potentiometer. All of the LM3 BRIGHT 5mW 635nm VISIBLE LASER PCBs have been designed to stack on top of each other to make the system much more compact. DIODE MODULE: This module emits an K142C This kit inc. PCB, K142A orange/red beam which is more visible and heatsink with fan& all onKit includes. board parts. brighter than some 650-670nm modules. $11 PCB, DB25 K1b2K K142C K142B K142B LM4 780nm / 5mW LASER DIODE MODULE $15 PC plug, & all Kit includes on-board 5mW, adjustable focus. Danger IR, hardley PCB, & all parts as visible. Ideal for medical applications. o n b o a r d shown LM5 635nm / 10mW LASER DIODE MODULE parts. $4010mW, adjustable focus. NEW LASER MODULES $27 $25 $29 LM6 650nm / 10mW LASER DIODE MODULE $16 10mW, adjustable focus. The above lasers consist of a laser diode, diode housing, APC (automatic power control circuit) driver, and collimation lens all factory assembled in one small module. 4.5V to operate & draws approx. 50mA & are around 13mm long. K224 3 CHANNEL TO 7 CHANEL INFRA-RED REMOTE CONTROL KIT Up to three kits can be used together to make a 21 Ch. system to operate from one remote control. The basic kit includes the PCB & all onboard components to build a 3 Ch. IR remote control including relays and screw terminals. The additional components required to expand to 7 Ch. are available in the K224E kit. If not used the remaining 4Ch. section of the PCB can be snapped off to reduce the overall size of the kit. 3 channel kit $25 (K224R) LS1 (NEW) 40mW+ GREEN LASER HEADS: With a 90-240VAC / 50-60Hz power 4 channel expansion kit $11(K224E) supply, laser 34 x 34 x 80mm; 240vAC power Remote control (pre-built)$6 (K224T) Complete package 7 channel supply 95 x 52mm. $270 kit with remote control $39 (K224P) LS2 (NEW) 40mW+635nm RED LASER HEADS Supplied with a small 100-240VAC / 50-60Hz. 9Ch UHF REMOTE CONTROL RECEIVER KIT. Output 5VDC / 500mA, 21mm x 56mm $200 This Kit uses our K226T kit to control 9 relays LS3 (NEW)BLUE laser diode 20mW: $1300 that can be set in any combination to momentary or latching at the flick of a switch. It can be USB WEB/PC CAMERA used to switch just about anything on or off, This great little colour camera will stand lights, motors etc. The pre-built UHF module on it's own base or clip on to your used in this kit has security encoding and laptop screen. Features include requires no tuning or alignment. Kit inc. white LEDs that turn on autoall onboard components, PCB and prematically when dark, built in built UHF module. $55 K226R base and clip, swivel head and USB cable. Software drivers are available for download from our 9Ch UHF REMOTE CONTROL TRANSMITTER KIT. website. USBC1 $35 The pre-built UHF module used in this kit requires no tuning or alignment. This kit includes PCB, all onboard components, 24 SECOND VOICE ? SOUND pre-built UHF module, 9V batter clip, suitable case and RECORDER MODULE membrain type keypad/label. Requires a 9V PP3 battery (not This small pre-built module will supplied). K226T $27... This kit can also be used with our TX7 record up to 24 seconds of sound at the push of a button, then play it back at the push of a second button. Requires 6VDC to operate. Measures 34mm X 22mm Comes with a 29mm speaker VRM1$10 CAM9 (NEW) MINI CMOS COLOUR CAMERA W/ AUDIO: Horizontal resolution: 380 lines, 1/3" CMOS Image Sensor, Minimum illumination: 3 Lux. Standard PAL Video Output. RCA Connections. Built-in microphone. Includes swivel mount. No Infrared LED's. Operates from 7 to 12V DC and draws 30mA. Dimensions 25 x 35 x 14mm. CAM9 $39 OUR 250W WIND GENERATOR IS NOW ON SALE FOR ONLY $449 These are serious 3ph 250W wind generators with blades spanning 2.2M. 12V or 24V. Included is a three phase rectifier unit with voltage and amperage metering and a regulator kit K220. 1 X 45kg box (720 x 440 x 230mm), & 1 X 27.5kg box (1540 x 220 x 110mm). For more information and instructions see our web site. HIGH POWER SHUNT REGULATOR KIT: Ideal for use with wind generators & solar systems. This kit prevents overcharging of 12V or 24V batteries & can even assist with hot water heating. Based on a voltage regulator IC (L4949) The kit uses the voltagesensing comparator section of the IC as its main switching device with hysteresis. Suitable for 250W+ operation. Kit inc. PCB & all on-board components. 4-CHANNEL UHF RECEIVER KIT WITH See Silicon Chip Magazine June 2005. (K220) $26 LIMIT/RESET INPUTS: This kit is an updated & cheaper version of the original K180 kit. It is still a 4channel UHF remote control with individual limit / reset This kit provides an interface input for each channel but without the "code hopping". between a 2400 baud serial line and Uses a pre-built and pre-aligned 433MHz UHF common character type LCDs that receiver module (RX7) (sold separately $11). use a HD44780 interface. It can use Combined with our Series V Transmitter (TX7), this kit inverted or non-inverted data from a can control 4 output relays in either momentary or PC, PICAXE, or other processor. latching operation. Features include software Features include high controlled variable backlight s e c u r i t y, r a n g e o f intensity, two auxiliary digital outputs & a "beep" output to ~100m, on-board high drive a peizo speaker. The layout of this kit allows easy current relays with connection to 14 and 16 pin single row & double row type LCD indicator LEDs, and connections. The serial inter-face is TTL. That is, the ideal screw terminals for easy state is a TTL logic one, or near +5 VDC. More details on web connection. Receiver kit site. The kit includes a PCB, programmed PIC16F628 or includes PCB and all onsimilar PIC IC and onboard components. $20... $30 when board components. purchased with a DL6 LCD. (K180B) $33 NEW KIT...K221 SERIAL LCD INTERFACE www.oatleyelectronics.com Suppliers of kits and surplus electronics to hobbyists, experimenters, industry & professionals. Orders: Ph ( 02 ) 9584 3563, Fax 9584 3561, sales<at>oatleyelectronics.com, PO Box 89 Oatley NSW 2223 OR www.oatleye.com major credit cards accepted, Post & Pack typically $7 Prices subject to change without notice ACN 068 740 081 ABN18068 740 081 SC_AUG_05 Vintage Radio By RODNEY CHAMPNESS, VK3UG The impressive AWA Radiola B32 transistor portable Australian manufacturers produced several high-performance transistor radio receivers during the 1960s – an era that was to herald the end of local domestic radio manufacturing. One such set was the AWA Radiola B32 transistor portable. Tennant Creek and Katherine. They transmit at night on 2310kHz, 2325kHz and 2485kHz and during the day on 4835kHz, 4910kHz and 5025kHz. The daytime transmissions are not usually heard in populous areas but some of the night-time transmissions can be heard quite clearly in these areas. Although broadcast-band sets dominated, some of the transistor receivers produced by Australian manufacturers during the 1960s were multiband sets, which meant that the ABC’s shortwave inland services could be heard almost anywhere in Australia. Of course, those original One interesting high-performance receiver from the era is the AWA Radiola B32 transistor portable. Produced around 1965, it has a large 195 x 12mm loopstick antenna, followed by a sensitive low-noise radio frequency (RF) stage which feeds an autodyne converter. A 2-stage 455kHz intermediate frequency (IF) amplifier then feeds a diode detector and three stages of audio amplification. The transformer-coupled output stage is wired in push-pull configuration and drives an oval loudspeaker measuring 150 x 100mm. The case is quite substantial for a transistor receiver and measures 320 x 200 (not including the handle) x 110mm (including the knobs). The main part of the case is made of leather, while the front of the set is metal and this is attached to a plastic inner frame. As can be seen in the photographs, there is quite a bit of room in the back of the set (to the left). This is used for the extra features included in the 4-band version of this set, the B33. Overall, the cabinet is of somewhat higher quality than some of the downmarket AWA transistor receivers. Due to its size, the set is quite heavy, weighing in at 3.3kg without the battery and around 4kg with the battery in place. It uses the now unobtainable 2761 battery but two D-cell battery inland services, located at Lyndhurst (Melbourne) and also near other capital cities, have long since closed down. In fact, the old Lyndhurst site is now a housing estate! However, there are now three stations that have taken over this role and they are located near Alice Springs, The AWA B32 transistor portable was a relatively large unit with a leather case and a metal front panel. This view shows the set after restoration. 94  Silicon Chip The B32 receiver siliconchip.com.au This is the view inside the back of the set, with the modified battery packs in the foreground. The modified battery packs are necessary because the original 2761 type battery is no longer available. holders – one for four cells and the other for two cells – will fit into the space that the 2761 occupied. In my case, I removed the battery plug and wired the battery leads to the two holders in series to obtain the required 9V. This arrangement works well and is the only “non-standard” work I needed to do in order to get the set working. The performance of the receiver can be enhanced by connecting an antenna and earth to the bayonet socket at one end of the receiver. In addition, there is a socket for an external 9V power pack and this can be used to extend the already long battery life of this set. However, there’s one important thing to note here: like most transistor receivers using PNP transistors, this set has a positive chassis. This means that the sleeve of the socket is also positive. Restoring the B32 For some time now, I have been keen to obtain the 4-band B33 version of this set and I still am. Even so, I jumped siliconchip.com.au at the chance when a B32 model was offered to me. The set had quite bad distortion but I thought that this would be easy to fix. Well, the fault was easy to find – a bit of careful probing with the signal tracer revealed that the audio was fine up to the loudspeaker. A quick check with a multimeter then revealed that one half of the speaker voice-coil was open circuit. But where do you get 80-ohm centretapped voice coil speakers? Answer – you can’t. I needed to get a close look at the speaker, which meant that the “works” had to come out of the cabinet. This initially involves removing three knobs and the six screws holding the chassis plate in position. That done, the small escutcheon around the external power inlet and the antenna/earth socket are removed, after which the chassis can be withdrawn from the cabinet. Finally, the four nuts holding the speaker were undone and the speaker removed. But could I repair it? I could see the break in one of the voice-coil leads, so I decided to attempt a repair using a small soldering iron, some thin solder and a short length of fine wire. I was in luck – the repair was successful. With the speaker now working again, the next step was to check the IF alignment. It needed only a minor tweak to get it right on the button. I then checked the front-end alignment but started getting some strange results. The oscillator was tracking with the dial calibrations so no work was needed there. However, I found that the loopstick antenna needed some extra turns to peak its performance at August 2005  95 This view shows the unit with the chassis out of the cabinet, as far as the loudspeaker leads will permit. The loudspeaker is a large oval-shaped unit, which contributed to the good sound. (TR2 & C5) adjustments. However, I couldn’t find anything wrong in the circuit and all the adjustments had been done correctly. Not long after, I had another reputable brand transistor set to restore. It too had an RF stage and it had exactly the same problem, only worse. Why? I have come to the conclusion that the MSP (Manufacturers Special Products) 3-gang padderless tuning capacitors have not been cut accurately and so the circuits do not track correctly. Assuming that the oscillator gang plates are cut correctly, then it appears that the RF and antenna capacitors have insufficient capacitance when the plates are fully in mesh. By contrast, the Kriesler 11-99 receiver uses a padderless twin tuning gang and the cut on these is near enough to be perfect. Its tuned circuits track very accurately and the set is extremely sensitive. It’s also worth noting that the B33 doesn’t suffer from this problem, as the three gang sections are identical. That said, the B32 is still a good performer. It’s just that it could have been even better. Cabinet restoration Fortunately, the cabinet was in very good condition and only required wiping over with a soapy cloth. In addition, a stiff brush was used to get dust out of the crevices in the front panel, while the knobs were scrubbed in soapy water with a nail brush. The cabinet is in such good order that it’s apparent that the set hasn’t been used much. Perhaps the fault in the speaker occurred quite early in its life, after which the set was safely stowed away on a shelf or in a wardrobe. Circuit details A full circuit diagram is pasted onto the inside back cover of the receiver, along with a diagram showing the dial stringing arrangement and a third diagram showing the locations of the major components (IF transformers & transistors). the low-frequency end of the dial. The antenna coil is wound almost right along the full length of the loopstick, so it’s not practical to move it to peak the performance. After adding the extra turns, the set worked very well at the low-frequency end of the dial but I couldn’t reduce the trimmer capacitor 96  Silicon Chip far enough to peak the performance at the high-frequency end. So was the distributed capacitance across the coil too high? I doubted this would be the case and decided to probe further. The components involved were TR1 and C6. The same problem occurred with the RF circuit Fig.1 shows the circuit details of the B32. It uses eight transistors, all PNP germanium types, so all voltages are negative with respect to the chassis (ie, positive chassis). The RF stage uses a 2N1637 transistor (VT1) which has automatic gain control (AGC) applied to it. A milliamp meter in the collector circuit displays the signal strength. VT2 (2N1639) and TR3 function as an autodyne mixer. Its output signal is at the intermediate frequency (IF, 455kHz) and this is fed to a top-cousiliconchip.com.au Fig.1: the circuit uses eight PNP germanium transistors in a conventional superhet configuration. Transistor VT1 functions as an RF stage, while the push-pull output stage (VT7 & VT8) drives an 80-ohm centre-tapped loudspeaker. siliconchip.com.au August 2005  97 Photo Gallery: AWA Radiola 46E to a pair of 2N217S output transistors operating in push-pull configuration. The operating bias on the 2N217S output transistors is stabilised by an AS2 compensation diode (MR4). This is necessary because the hotter the environment, the more current the output transistors will draw. At the same time, the compensation diode also conducts more and the voltage across it decreases. As a result, the forward bias on the output transistors is reduced and so they are automatically “throttled” back. This means that the standing current drawn by the output transistors is maintained at about the same level, regardless of temperature. So MR4 is there to prevent what is known as “thermal runaway”. There is no conventional output transformer. Instead, as mentioned previously, the output transistors directly-drive an 80-ohm centre-tapped loudspeaker. It’s just as well the loudspeaker was repairable. They’re virtually unobtainable these days and it would have been quite a lot of work to modify the audio amplifier stage to suit a different speaker. Servicing Manufactured by AWA in 1932, the Radiola 46E TRF console was a 5-valve “little brother” to the larger 55E console featured last month. In fact, its external appearance was almost identical to the 55E but it featured one less RF stage (and one less knob). The valve line-up was two 235 RF amplifiers, a 224A detector, a 247 audio output stage and a 280 rectifier. Photo: Historical Radio Society of Australia, Inc. pled bandpass pair of tuned circuits (TR4 and TR5). The first and second IF amplifiers both use 2N1638 transistors (VT3 and VT4), which are neutralised C22 and C24 (after all, these are solid state equivalents of triodes)! The IF stage then drives diode MR3 which functions as the detector. The detector output is fed to volume control RV1 and then to the base of the first audio stage (VT5, 2N408). 98  Silicon Chip This stage also acts as an AGC amplifier. The greater the signal, the higher the current through VT5 for a given setting of the volume control (ie, the transistor turns on harder). This in turn pulls VT1’s emitter more negative and reduces its gain. The audio output from VT5 appears at its collector and is fed to VT6 (another 2N408) via a 4mF capacitor (C39). It’s output is then transformer-coupled Unfortunately, this set can be rather awkward to service. The controls, tuning gang and ferrite rod are all easily accessed but the PC board can only be removed by using a large soldering iron to unsolder it at four points on the metal mounting plate. In addition, the RF and oscillator trimmers can only be adjusted after removing the chassis from the case. This is rather a poor idea, considering that it would not have been hard to use trimmers that are independent of the gang and positioned with their adjustment slots easily accessible from the back. By the way, once the PC board has been freed, it’s important to make sure that it cannot touch the (positive rail) chassis. Placing paper or a soft cloth between the board and the metal chassis plate is a worthwhile precaution against possible damage. Summary In summary, there was very little wrong with the set, the faulty speaker being the main problem. All in all, it is a very good set that’s somewhat SC spoiled by its tuning gang. siliconchip.com.au PRODUCT SHOWCASE New 4-channel USB ’Scope from Pico The four-channel PicoScope 3424 PC Oscilloscope from Pico Technology has 12bit resolution, 20MS/s sampling rate and a large 512K memory buffer. A USB 2.0 connection eliminates the need for an external power supply and makes connection and installation easy. It offers 1% voltage accuracy and 100ppm timebase accuracy. Timebases from 500ns/div to 50s/div and voltage ranges from ±20mV to ±20V make it suitable for a wide range of applications, including general analog, audio and digital design and repair. It produces high-quality waveforms that can be vertically zoomed to reveal even higher levels of detail. This resolution gives the instrument a 72dB dynamic range in spectrum analyser mode, which enables it to detect low-level harmonics for applications such as noise and vibration analysis. The PicoScope 3424 is supplied with the PicoScope and PicoLog software applications, a 32-bit Windows driver and support for numerous third-party applications. PicoScope provides oscilloscope, spectrum ana- lyser and multimeter functions, with the ability to measure, save and print waveforms. PicoLog turns the PC into a powerful Data Logger that can export data to a spreadsheet or display it as a graph, in real time or using recorded data. These programs are easy for the novice to operate but also contain a full range of advanced features for expert users. Software updates are available free of charge from the Pico Technology website. Contact: Emona Instruments Pty Ltd PO Box 15, Camperdown NSW 1450 Tel: (02) 9519 3933 Fax: (02) 9559 1378 Website: www.emona.com.au Jaycar’s new Scoreboard kit is already upgraded! Even before its release, the Jaycar Electronics Sports Scoreboard (SILICON CHIP, March-May & this month) has already had an upgrade. While the kit overwhelmingly follows the design in the magazine, in response to requests fromreaders, the Jaycar kit has now been modified to include fouls and include other minor improvements. Jaycar submitted one of their completed kits for evaluation and it looks very good! The complete kit, including the desk controller (not shown here), is now available from Jaycar Electronics stores, for $799.00 siliconchip.com.au Altronics’ Sydney store DMM GIVEAWAY Altronics maintain their Auburn electronic enthusiast staff are the best in the business as indeed is their electronics showroom which caters for the trade and serious hobbyist alike. This month they released their latest 324 page electronics catalog and invite customers to visit the Auburn store and see for themselves both the showroom and exciting new products. As an enticement they are offering you a rather excellent digital multimeter absolutely free with any purchase (even a 50 cent purchase!). Simply ask for the free multimeter mentioned in SILICON CHIP magazine, August issue. Strictly limited to one per person during August 2005. This fantastic little 3.5 digit multimeter (Cat. No. Q 1053A) features 19 ranges including an in-built transistor and diode test function. This meter provides a surprising number of features and facilities and would be perfect for the budding enthusiast or a spare meter for the toolbox or glovebox. ONLY at Altronics (Sydney store) 15 Short Street, Auburn NSW 2144 AUDIO MODULES broadcast quality Contact: Jaycar Electronics PO Box 6424, Silverwater NSW 1811. Tel: (02) 9741 8555 Fax: (02) 9741 8500 Website: www.jaycar.com.au Manufactured in Australia Harbuch Electronics Pty Ltd 9/40 Leighton Pl. HORNSBY 2077 Ph (02) 9476-5854 Fx (02) 9476-3231 August 2005  99 Spider: a remote monitoring, control and alarm system Halytech Spider SMS LC is an integrated remote monitoring, control and alarm system designed and manufactured in Australia. You can connect virtually any type of sensor to the Spider and receive alarms by e-mail or SMS when readings go outside your pre-defined range. Or you can send SMS commands to the Spider to remotely control a device. Every computer can communicate with a Spider. No special software is required. Simply start your web browser and surf the Spider’s web pages! Each Spider SMS LC incorporates a high capacity data logger. Data is downloaded in a standard format readable by all popular spreadsheet and database programs. Or you can automatically receive data reports as email attachments. Spider SMS LC includes all software, hardware and a GSM or CDMA mobile phone module. It is housed in a compact, economical plastic enclosure making it ideal for use by system integrators and OEM applications. World’s first VOIP & landline phone in one Typical applications include: • Environmental monitoring • Process control • Pump control • Water treatment • Waste management • Irrigation • Rural applications • Air conditioning Contact: Halytech Pty Ltd Box 6983, Baulkham Hills BC, NSW 2153  Tel: (02) 9862 9955 Fax: (02) 9642 1928 Website: www.halytech.com.au Unwired getting ready for WiMAX: mobile, go-anywhere wireless broadband Unwired Australia will receive WiMAX compatible equipment from Navini Networks from late 2005 – paving the way for a seamless and cost-effective transition to WiMAX. WiMAX will deliver truly mobile highspeed broadband access to users to almost anywhere in Australia and ultimately roaming access around the globe. Navini will start shipping Ripwave dualmode (modems) by the end of 2005. The Ripwave dual-mode modem is software upgradeable to Navini’s WiMAX 802.16e system (mobile-capable WiMAX) and can switch easily between Unwired’s current technology and WiMAX 802.16e. Unwired is the only carrier in Australia that can easily transition to WiMAX when the mobility standard is introduced. Unwired owns most of the 3.5GHz spectrum in Australia which is the preferred WiMAX band. Unwired Australia say that WiMAX in Australia will revolutionise mobile data in the same way the GSM standard transformed voice technology in the 90s. The WiMAX momentum is continuing with 100  Silicon Chip major carriers rolling out WiMAX networks and manufacturers such as Intel and Fujitsu now producing WiMAX chips for modems and eventually other portable devices such as laptops. The mobile version (802.16e) of this standard is expected to be ratified at the end of this year. Navini will also deliver “Ripwave” base stations, targeted for early 2006, that will be software-upgradeable to 802.16e and will continue to support the Smart Antenna technology available from Navini today. Unwired plans to start receiving these base stations in the first half of 2006. This, in conjunction with the Ripwave Element Management System that will support both the Navini pre-WIMAX and WiMAX network, will facilitate a smooth transition to 802.16e. We have mentioned Microgram’s VOIP phones before in this column, suitable for Skype or other “free” internet-based systems. But now Microgram have announced what is claimed to be the world’s first phone which can operate as a VOIP phone or a conventional DECT (cordless) landline phone. The Cordless DUALphone is a cordless telephone that can be connected to a normal telephone socket and a USB port on a PC. What is more, the display shows whether your friends who also use Skype are online. If they are, you simply have to press the appropriate green button and talk to them for free – no matter where they are in the world. So you get the best of both worlds: a cordless phone which can be used for conventional calls or a Skype phone for free local, long distance and international calls to other Skype users (requires internet connection, preferably broadband). In fact, with the new Skypeout service, the phone can be used to access very low international rates for non-Skype contacts. The Cordless Skype Phone 2-in1 (Cat No. 10172-13) is priced at $220.00. Extra handsets (Cat No. 10173-13) are $110.00. Contact: Contact: PO Box Q74, QVB, Sydney NSW 1350 Tel: (02) 9231 6055 Website: www.unwired.com.au 1/14 Bon Mace Cl, Berkeley Vale 2261 Tel: (02) 4389 8444 Fax: (02) 4389 8388 Website: www.microgram.com.au Unwired Australia Microgram Computers siliconchip.com.au MATLAB software: sounds good to DEQX Australian digital audio technology company, DEQX, has spent seven years developing the sound quality of audio speakers. Its technology is now used in the famous Abbey Road recording studios in London. The evolution of affordable floating-point Digital Signal Processing (DSP), has enabled DEQX to develop a family of unique measurement, calibration and playback algorithms that allow speaker designers and users to correct many of the problems common in speakers for decades. The result is an audio correction process that improves sound clarity by correcting both design flaws in the loudspeakers themselves and natural flaws caused by the speaker’s interaction with the listening room’s acoustics. The “DEQX Calibrated” technology allows detailed speaker and room measurements and provides tools that can enhance room acoustics while improving speaker accuracy, imaging and soundstage, even in low-cost speaker systems. Key to the continual development of DEQX Calibrated technology is hours of trialling and testing algorithms for the software, hours that could easily have turned into weeks if not for the use of MATLAB mathematical software from The MathWorks. The MathWorks (distributed in Australia by Ceanet) is the world’s leading developer and supplier of technical computing software for engineers and scientists in industry, government, and education. With more than 65 products based on MATLAB and Simulink, The MathWorks provides high-productivity tools and consulting services to solve challenging problems in automotive, aerospace, telecommunications, process industries, electronics, biotechnology and pharmaceuticals, finance, and earth and planetary sciences. www.mathworks. com. In particular, DEQX uses MATLAB to test DSP algorithms for speaker and room correction. MATLAB is a powerful mathematical computing, visualisation, modelling and simulation tool that helps developers analyse enormous amounts of data and simulate possible situations to help predict outcomes. Software Engineering Manager at DEQX, Brett George, said MATLAB provided the best platform for their complicated signal processing requirements. MATLAB has been used extensively to develop DEQX’s custom speaker and room correction software, which are amongst a range of products based on the calibrated correction process. The products are now allowing speaker designers to provide levels of accuracy and clarity in speakers which near the quality of the other components in their system. Contact: Ceanet Pty Ltd Level 5, 15-19 Bent St, Sydney NSW 2000 Tel: (02) 9232 3699 Fax: (02) 9232 3332 Website: www.ceanet.com.au The DEQX Calibrated PDC-2.6P Digital Loudspeaker/Room Correction Preamp and Crossover Processor. 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The company has passed stringent tests and assessments set out by SAI Global to meet world-wide standards in ESD handling. Testing includes the areas of transport, unpacking, handling, packaging and distribution of ESD. Farnell InOne’s standards in ESD handling involve the use of protective packaging materials, custom ESD workstations, equipment including siliconchip.com.au grounding straps, and special handling procedures. Each employee who has access to ESD areas is fully trained in procedures and is equipped to handle items in order to prevent ESD problems. Problems with ESD can cost companies thousands of dollars in equipment failures, damage and product recalls. Contact: Farnell InOne PMB 6, Chester Hill NSW 2162 Tel: 1300 361 005 (NZ 0800 90 80 80) Website: www.farnellinone.com WebLINK: jedmicro.com.au JAYCAR JAYCAR ELECTRONICS ELECTRONICS WebLINK: WebLINK: www.jaycar.com.au www.jaycar.com.au A J 2005 83 2005  101 hellschreiber - revisited Regular readers will recall Stan Swan’s enthusiastic “Hellschreiber” feature back in the May 2005 issue of SILICON CHIP. It attracted a lot of interest and correspondence – not all of it 100% positive! First of all, a brief recap for those who might have missed it. Stan talked about the “rediscovery” of this WWII-vintage communication system, actually used to great effect by the German army with their portable “Feld-Hell” electromechanical units. In some ways, Hellschreiber may be thought of as a forerunner to modern-day facsimile machines, since it writes an image to paper. However, it was/is limited to transmission and reception of letters/numbers. Stan talked about the free Hellschreiber software available on the ’net and then went on to describe how it could be used on the “data only” channels 22 and 23 of the Australian UHF CB radio system, along with a suitable computer and sound card. Whoops! What Stan didn’t realize at the time was that the “data only” channels are restricted to absolutely miniscule amounts of data – three seconds maximum in each hour. This is much less than Hellschreiber requires. We only twigged to this ourselves when several readers (presumably users of the data-only channels!) wrote in to tell us of the transgression. Item Channel 6 22 23 Carrier Frequency (Megahertz) 476.950 476.975 It’s not mentioned at all on the Australian Communications Authority (ACA) website Class Licencing page (http://internet.aca.gov.au/ACA INTER.65650:STANDARD:pc= PC_1265). In fact, you have to go right back to the ACA’s “Radio Communication (Citizen Band Radio Stations) Class Licence 2002” page (http://internet.aca.gov.au/acainterwr/aca_ home/legislation/radcomm/class_licences/cbrs.rtf), then wend your way right through to Schedule 1 (CB station operational requirements) and finally work your way down to Section 6(g), before you find the specific reference to Channels 22 and 23 having a time limit. Phew! No wonder people don’t know about it! Moreover, those regulations, reproduced below (with the relevant clause in italics), don’t even mention the limitation to “telemetry and telecommand” – something Hellschreiber definitely is not. (Telemetry and Tele-command are digital signals, transmitted from one UHF CB to another, designed to either do something or read something – such as open or close an electronic gate lock or measure the water level in a dam on the opposite side of the property). To find those limitations, you need to go back to the Class Licencing Page mentioned above and . . . oh yes, there it is – Telemetry and Telecommand. Therefore, we must warn UHF CB users that, despite their being no licence requirements for their operation, there are most certainly regulations which have to be obeyed and the authorities could take a very dim view of people tying up the data channels with such things as Hellschreiber or even SSTV. (Stan had also been toying with the idea of using UHF 22/23 for SSTV but following our advice has shelved that idea, too!) There was one other small oversight in the Hellschreiber article. Stan supplied a photograph of a Hellschreiber transceiver (which we published on page 42 of that issue), which he had obtained from an obscure site on the ’net (good old Google!) and he‑ could not determine who, if anyone, owned the copyright. However, it seems that the photo in question may have itself been copied from the website of another NZ ham, Murray Greenman, ZL1BPU, who was not happy that he was not acknowledged as the rightful owner. To be honest, had we known about an original version of this contentious photo (http://www.qsl.net/zl1bpu/ FUZZY/History/fh44.jpg) we would have asked for permission to use it instead because it is of significantly better quality than the one Stan gave us and we actually printed! In any case, we apologise to Murray Greenman for the apparent inadvertent use of his photograph. SC Restriction A transmitter employed in a CB station: (a) must operate with a transmitter power not exceeding 5 watts; and (b) must not exceed an EIRP of 8.3 watts; and (c) must operate with an occupied bandwidth not exceeding 16 kHz; and (d) must not exceed a carrier frequency error of ±3 kHz; and (e) must not exceed an adjacent channel power of –22 dBm; and (f) must not exceed a conducted spurious emission of –30 dBm; and (g) must operate on a duty cycle of not more than 3 seconds in any period of 60 minutes; and (h) must be fitted with a device that shuts the transmitter down after 3 minutes of continuous operation. A receiver employed in a CB station must operate with a conducted spurious emission not exceeding –57 dBm. Note: The use of single frequency store and forward repeaters is permitted. 102  Silicon Chip siliconchip.com.au There’s no point making the best speakers in the world if they’re not affordable said of VAF “They are the best speakers I have ever heard.” said “We have yet to hear another system that sounds as good as this one.” * said “The ultimate in high fidelity performance with the best bass in the world”. It’s nice that these people are impressed by VAF speakers. We want you to be too. For the enthusiast, most models are also available as ‘ready-to-assemble’ kits. ... Interested? FreeCall 1800 818 882 Eleven of the best loudspeakers available, and they’re all affordable siliconchip.com.au * Three years on powered speakers/subwoofers August 2005  103 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; or send an email to silchip<at>siliconchip.com.au PICAXE control for 1W Luxeon driver I want to make a PICAXE control the dimming of a Luxeon Star 1W LED. How can I modify your 1W Star Experimenter’s Power Supply circuit (featured the December 2003 issue) to enable the PICAXE to dim the Luxeon using its PWM function? Is it as simple as connecting the PICAXE to the out of the 555? (E. P, via email). • Although we haven’t tried it, we can’t see why you couldn’t feed the PWM output from a PICAXE into the base of Q1 (via the 3.3kW resistor), replacing the 555 and associated circuitry. Nail detector wanted I know you have done a number of metal detector projects, however they have been sizeable devices designed to detect objects deep below most surfaces. How about a handheld device? I re-use a lot of old building material and nails are sometimes difficult to find until you hit them with a power saw! The device I have in mind would be about the same size as the ones used at airports, hopefully a lot cheaper and be able to detect nails and/or staples up to about 25mm below the surface of timber. Hope you can help. (I. B. Monash, ACT). • None of our metal locator projects would be suitable. You would be better off using a stud locator, available from hardware stores for about $30. Some of these are quite good at locating nails or screws in walls, so they would probably work for your application. PIC programmer question I was wondering if the Parallel Port PIC Programmer and Checkerboard, described in March 2001, can program a PIC16C71 chip? Do I also need a MAX232 to transmit data to a PC from the PIC16C71? (D. V., via email). • The hardware can be used to program the PIC16C71, although the software described in the article is not suitable. You’ll probably need to update to one of these packages: (1). IC-Prog from www.ic-prog.com; or (2) Lip-Sync Problem With Plasma Screen With plasma screens increasingly more common, lip sync where the audio is in advance of the video is a common problem. This appears to be caused by video processor delays relative to the audio and can be quite variable, depending on the mode of viewing. High-end audio amplifiers provide variable audio delay but for many readers, a low-cost digitally selectable delay in the order of 20160ms would be an ideal project to correct an unexpected problem. Have you any projects that already fit the bill or would this be a new adventure? (P. D., via email). • There is no easy answer to this 104  Silicon Chip problem. As we understand it, depending on the particular mode of display and the particular plasma screen, the video picture can be delayed by almost half a second. The delay is caused by the considerable amount of processing required to turn the video signal into a huge pixel display. So even 160ms will not be enough. Nor would it be a simple project concept. Our advice for anyone purchasing a plasma screen for use in a home theatre system is to thoroughly research this problem before you buy. If possible, try the screen with the proposed audio equipment it will be used with. PICALLW from www.picallw.com. The details on using this software were published in the “Updating the PIC Programmer & Checkerboard” article on page 79 of the July 2003 issue of SILICON CHIP. Note that if you’re developing a new project, we would recommend selecting one of the more recent “F” (FLASH memory) series microcontrollers, which can be erased and reprogrammed in circuit. As far as a PC serial port connection is concerned, you’ll need some kind of RS232 interface and the MAX232 is one of the easiest ways of building one. The PIC16C71 does not include a UART, so you’ll need to implement this yourself in firmware. An application note (AN555) is available from Microchip (see www.microchip.com) describing how this can be achieved. Powered subwoofer has thump problem I have just recently purchased a Surround Sound home entertainment centre comprising a Yamaha RX-V650 receiver with the following speaker configuration: B&W DM601 (Mains), B&W DM600 (Rears), B&W LCR600 (Centre) and B&W ASW300 (Subwoofer). It is a very impressive system with one small problem. I am getting irregular “thumps” over the Subwoofer when the system is powered on. It would appear the thumps are being transmitted via the amplifier, as they disappear as soon as I disconnect the subwoofer to amplifier speaker cable. I have tried all number of remedies, including a surge protection power board, disabling sleep mode on the subwoofer, isolation of mains circuits, relocation of the subwoofer, etc, but have made no impact. I am reasonably confident most of the interference is being initiated by my fridge when it powers up/down but am unsure what to do next. Can siliconchip.com.au you offer any suggestions as to what I might try to fix the problem. The sound is not detectable on any speaker other than the subwoofer. I am running Monster Cable 16 gauge to all speakers (fronts all bi-wired), with a special interconnect cable from the subwoofer to the amplifier. At present, I am being forced to leave the subwoofer powered off, as the thumps are very annoying. (C. D., via email). • Our guess (and it is only a guess) is that the interference from your fridge is being picked up by the input signal lead to your powered ASW300 subwoofer. Keep this lead as far away from mains cables as you can (including cabling buried in the walls). If the input cable must go close to a mains cable, try to route it at right-angles, to minimise pickup. Electronic blood pressure monitor I received an electronic blood pressure monitor as a gift. The device is fully automatic and battery-powered only. I have connected it to a 6V DC lab power supply and it worked perfectly except for the valve which controls the air outlet. When the device is turned on, the valve opens and stays open while the pump is pushing air in to the armband. As soon as the batteries are replaced, the monitor functions perfectly again. Can you solve the mystery and help? (B. K., via email). • Our guess is the that the bench power supply cannot deliver the peak current required for correct valve operation. Try connecting a 2200mF electrolytic capacitor across the output of the supply. This will reduce the output impedance of the supply and it should then be able to supply a higher peak current. TV aid for hearing impaired I am hard of hearing and use a set of IR phones while watching TV. This is fine at home but not so good when I visit friends or stay at a motel. The IR transmitter needs to be plugged into an audio output on the TV and of course, not all TVs have this. And even if they do, it will be tucked away right at the back of the set. Would it be possible to create some kind of acoustic coupling between the siliconchip.com.au Audio Interference To Video Signals I wondered if you had a project that could help with the following problem. Recently, our church installed a data projector set up and then the computer was moved to the rear of the building to make operation less distracting. The video cable length increased from three metres to 25 metres. The system works well but we are now getting an interaction between the hearing aid induction loop and the video, where I presume the longer cable is acting as an inductor. The interference appears as dark horizontal bands which are in time with the audio and increase in width and visibility as the audio gets louder. My impression is that low frequencies are the main contributor as it is most noticeable when there is a lot of bass but then that also usually means more volume! The problem disappears if I turn off the hearing aid loop or pull down the mixer feed to the hearing aid loop during loud audio. When we ran only a short cable to the projector there was no problem but now we have a long cable the issue has arisen. I have tried two different high-quality video cables, transmitter and the TV set? It doesn’t have to be hifi – I only want to hear the program dialog. Years ago, when phoning England was a once-a-year event, I used to record the phone conversation onto a cassette recorder using a little gadget with a rubber sucker. This was stuck onto the phone and did the job beautifully. So could it be done? (J. G., via email). • The easy solution may be to use a radio microphone, along the lines of that described in the November 1998 issue. Just place the microphone in front of the TV speakers. If you use a lapel microphone, you might be able to clip it to the front of the TV set. You could then pick up the signal in a small FM radio with earphones. This will not be a hifi solution because there will be a tendency for the microphone circuit to pick up frame with no difference between them. The loop runs around the entire sanctuary at floor level or just above, so all cables are actually within the loop area and have to physically cross the loop cable at one point to reach the projector. I know the loop field is strong, as using inductance headphones, it is possible to hear some distance (up to 10 metres or so) outside the building. The simplest solution would be to install some form of automatic limiting device at the audio mixer feed to the loop amplifier to replicate what we do manually, pull back the fader, like an AGC in reverse. Have you ever had such a project? I do not know if filtering the video would work but if so, we would need a filter at each proposed output point, as the final configuration has video distribution amplifiers. (G. C., via email). • We don’t think there is any easy way to keep the low-frequency audio signal out of the (unbalanced) video cable since you have such a long run. The only practical solution we can think of is to send the video signal via optical fibre if that is possible or send it via a 2.4GHz link. buzz from the TV’s CRT deflection circuitry. Alternatively, if you can feed the signal from a lapel microphone into your IR headphone transmitter, you could achieve the same result. Master volume control for PortaPal The PortaPal project in the February and March 2003 issues is a great PA amplifier although it does not include a master volume control. Would it be feasible to place a potentiometer in the feedback of IC5a in place of the 15kW resistor to achieve this? (M. M., via email). • A volume control of 10kW would need to be placed at the output of op amp IC5a, with the wiper connecting to point “A” on the circuit, before the 1mF coupling capacitor and tone August 2005  105 Question On Charging Battery Packs Many battery packs for drills and cameras have three terminals. Can you explain what the third terminal does? I have pulled the battery pack for my Black & Decker drill apart and found that the third terminal is a tap half way up the battery chain. I can only assume that some part of the charger circuit is looking for less than the full voltage rail (ie, presumably the fastidious control circuitry needs less volts than the power control circuits) but it does seem like an appalling practice to deliberately run some of the cells down to a lower state of charge than control stage IC6a. You will need a 1mF coupling capacitor at the output of IC5a. Dimming the PicToc clock Your July 2001 PicToc clock can be used in a car but is there an easy way to dim the display at night? I can only think of switching in resistors to RA0, RA1, RA2 & RA3 separately on the PIC chip, when the parking lights are on. I also want to turn off the display when the ignition is off. In this case, I would have to use relays to disconnect the RA outputs completely. Is there an easier way. (H. G., Port Augusta, SA). • There is no easy way to dim the display except, as you say, to switch in different resistors for the segments. You could use reed relays to switch resistors in parallel with higher value resistors, so when the relays are closed, the LEDs will be brighter. Doing all that requires no less than eight reed relays. Messy! VK Powermate modifications I want to build the VK Powermate 25 (EA, February 1990) but want to modify it and need advice as to whether this is possible. The plan is to have three stepped output voltages: 6V, 12V and 24V, using a 3-position rotary switch and 106  Silicon Chip their mates. (P. M., via email). • The tapping is probably there so that the batteries can be charged as two series strings. This is better than charging the whole set of cells in series and closer to the ideal of charging each cell individually. Alternatively, on some battery packs, the third terminal is actually a thermistor output. The thermistor is buried in the battery pack and acts as a temperature sensor. It effectively shuts down the charging circuit when the battery pack temperature rises at the end of the charging cycle to prevent overcharging and increase battery pack life. presets in place of RV1. I suspect a pull down/up resistor on pin 4 of the LM723 would be a good idea as well, to stop the output going sky-high during movement of the rotary switch. The crowbar circuitry will also have to be changed and I think the easiest way is to make it trip at anything higher than say 27-28V (for simplicity). I’m just not sure what has to be changed to do this. The transformer I have is rated at 28V AC <at> 20A. (S. W., Auckland, NZ). • We would not recommend you upgrade this supply with your 28V transformer and then provide adjustable output. It would need massively larger heatsinks to cope with the greatly increased power dissipation at the two lower voltage settings Conversion of AM car radio to FM reception Can you please help with a kit or information on how to convert an old AM car radio to an FM unit internally (electronically) so as to keep the outside appearance. (K. M., via email). • What a question. We don’t have any information on how to do such a conversion and we would have to say that it would be practically impossible to do. What sort of old car radio are you considering? A vibrator-powered valve unit, a push-button unit with permeability or maybe an early germanium transistor unit with transformer cou- pling between the audio stages? In each case, the only practical approach would be to scrap the entire internal circuitry and just end up with the metalwork and then try and adapt a modern circuit to the existing tuning dial. If you have an old car fitted with an original radio, our advice would be to get it restored. It will be far more authentic that way. Cable for PIC-powered rain gauge I am interested in building the PICPowered Rain Gauge described in the June 2000 issue and have the following questions in relation to some aspects of the design. I saw a commercial unit on the internet and this unit also used a 10m cable to connect the detector with the electronics. Is there a specific reason why the cable is 10m in length? If the situation required it, could the cable be longer or shorter, without affecting the operation of the rain gauge? Does the cable have to be passed through a grommet and be soldered directly to the PC board or can it be terminated with a stereo 3.5mm phono plug with a suitable socket fitted to the box and terminated on the PC board, or perhaps even use an RJ12 plug and socket. (P. M., Karabar, NSW). • The wire length can be more than 10m and you can use a jack plug and socket. Bridge mode for Mosfet amplifier modules In August 2001, you described a 200W Mosfet amplifier module put out by Altronics. I built a pair of them into an old AT case as a disco amplifier for my son. He is upgrading his gear and wants to know if they can be run in bridge mode? Can you help with any information on this and what sort of power into what load we may expect? Have you described a circuit or kit to enable the bridging? (T. C., via email). • The modules can be run in bridge mode but only into an 8-ohm load whereby they will deliver a total of around 400W. We have not designed a bridge adaptor but you can refer to the design featured in the June 1985 issue of “Electronics Australia”. We can supsiliconchip.com.au ply a photocopy for $8.80 including postage within Australia. Notes & Errata Moving coil preamp for the LP Doctor Shunt Regulator, June 2005: transistors Q3 & Q4 are shown incorrectly oriented on the overlay diagram and photos and must be rotated 180°. The source and drain markings for the SDP55N03L Mosfet shown at the foot of the circuit diagram are reversed and the 47kW resistor in the collector circuit of Q3 connects to 5V rather than V+ as shown. Depending on circuit tolerances, it may not be possible to adjust the trip voltage to 15V as described in the text. To improve the adjustment range, some changes to the resistive divider connected to pin 2 of the L4949 are required. For use with 12V systems, replace the 120kW resistor with a 100kW value, the 12kW with a 9.1kW and the 1kW resistor with a wire link. All resistors must be 1% tolerance types. Assuming a nominal reference of 1.23V, this will give an adjustment range of about 13.1V to 15.9V. For 24V systems, replace the 120kW resistor (connected to VR1) with a 24kW value, the 12kW with a 4.7kW value and the 1kW with a wire link. The120kW resistor connected to V+ must be replaced with a 15V, 0.5W zener diode. The effect of the zener is to reduce the hysteresis voltage so that it remains about the same as for the 12V system. Assum- Have you ever published an RIAA preamp for moving coil cartridges. Alternatively, what modification do I need to make to the LP Doctor to match an MC cartridge to it? (P. S., via email). • The preamp in the LP Doctor cannot itself be modified to provide more gain but the inclusion of the following stage involving IC2 probably means that enough overall gain is available, provided the gain control (VR1) is well advanced. If more gain is required, change the 10kW feedback resistors between pins 1 & 2 and 6 & 7 of IC2 to 22kW. Powerful horn project wanted for car Having recently encountered a Bdouble petrol tanker trying to move into my lane while I was still in it, I found myself wondering if the driver could hear the puny horn of my car in his cab so far away, over the clatter of his own truck. Car horns today are about 60mm in diameter and are wimpish tooters! This got me thinking on the possibility of making a tone generator and using a horn speaker to make a car horn that sounds like a car horn! This could be a fun and unusual project for those of us who want a better warning device. The tone could simply emulate the sound of real horns like cars used to have when cars themselves were real. Is it worth considering as a magazine project? (P. C., via airmail). • It really is not worth doing as a magazine project. One of our staff member’s wives has a Toyota Avalon. It is a great car but comes with a single wimpy horn. That was easily fixed. ing nominal reference and zener voltages, the adjustment range after these changes will be about 25.9V to 30.5V. SMS Controller, October & November 2004: the supplier mentioned in the article (mobileextras.com. au) no longer stocks the data cable needed to connect the phone to the controller board. The project requires a Nokia DAU-9P or compatible data cable with an RS232 serial (not USB) connector. Cellink market a suitable cable, part number MDC887. You may be able to obtain one of these through your local mobile phone accessory store, or you can order one from Wagner Electronics Services, phone (02) 9798 9233 or on the net at www.wagner.net.au. Meter Probe Extensions, May 2005 (Circuit Notebook): the PC board pin sockets supplied by Jaycar (Cat. HP-1260) may vary from those described in the text. If the original items prove to be too small for your probe tips, then an alternative is to use standard female bullet connectors. These will need to be gently squeezed with pliers to close the contacts slightly for a snug fit over the probe tips. He had the Toyota dealer fit a pair of two tone horns purchased from a car accessory outlet. The cost was less than $100 and now the horns are loud SC enough to wake the dead! 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. 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Free software DaqFactory Express, Labview driver and ActiveX component. Signal Conditioners non isolated and isolated – convert thermocouples, RTDs to 4-20mA or 0-10V. Fully programmable. Pixel Programmable Controller with 4 analog inputs, 8 digital inputs and 8 relay outputs. Uses a Picaxe 28X. Programmed in BASIC. Temperature and humidity sensors N1500 universal process indicator. Budget-priced displays thermocouple, RTD, 4-20mA and 0-5V readings. Fully programmable. Box of Connectors – choose BNC, UHF, N Type or RS232 gender changers and converters together. Serial and Parallel port relay controller cards. Pump and Trip Alarm Controller card. Duty-Standby operation. MicroProgrammers for Atmel and PIC chips. 2, 4 & 8 Relay Cards suitable for TTL and Open Collector Outputs DC, Stepper and Servo Motor controller kits. Switch-Mode, Battery Chargers and DC-DC converters. Full details and credit card ordering available at www.oceancontrols.com.au. Helping to put you in control. USB KITS: GPIB Interface, Thermostat Tester, LCD Module Interface, Stepper Motor Controller, PIO Interface, DTMF Transceiver, Thermometer, DDS HF Generator, Compass, 4 Channel Voltmeter, I/O Relay Card, USB via LabVIEW. Also available: Digital Oscilloscope, Temperature Loggers, VHF Receivers and USB ActiveX (and USAugust 2005  109 Silicon Chip Binders New New New Mark22-SM Slimline Mini FM R/C Receiver REAL VALUE AT $12.95 PLUS P & P TAIG MACHINERY These binders will protect your copies of S ILICON CHIP. They feature heavy-board covers & are made from a dis­ tinctive 2-tone green vinyl. They hold up to 14 issues & will look great on your bookshelf. • • • • • 6 Channels 10kHz frequency separation Size: 55 x 23 x 20mm Weight: 25gm Modular Construction Price: $A129.50 with crystal Electronics PO Box 580, Riverwood, NSW 2210. Ph/Fax (02) 9533 3517 email: youngbob<at>silvertone.com.au Website: www.silvertone.com.au Micro Mini Lathes and Mills From $489.00 Stepper motors: 200 oz in $89.00, 330 oz in $110.00 Digital verniers: 150mm $55.00, 200mm $65.00 59 Gilmore Crescent (02) 6281 5660 Garran ACT 2605 0412269707 H 80mm internal width H SILICON CHIP logo printed in gold-coloured lettering on spine & cover H Buy five and get them postage free! Price: $A12.95 plus $A7 p&p per order. Available only in Aust. Silicon Chip Publications PO Box 139 Collaroy Beach 2097 Or fax (02) 9979 6503; or ring (02) 9979 5644 & quote your credit card number. Foam surrounds,voice coils,cones and more Original parts for Dynaudio,Tannoy and others Expert speaker repairs – 20 years experience Australian agents for products Trade welcome – email for your user ID Phone (03) 9647 7000 speakerbits.com.au   Use this handy form Enclosed is my cheque/money order for $________ or please debit my  Bankcard   Visa    Mastercard Card No: _________________________________ Card Expiry Date ____/____ Signature ________________________ Name ____________________________ Address__________________________ __________________ P/code_______ 110  Silicon Chip       BDOS.exe file) to control our kits from your own application. www.ar.com. au/~softmark 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 Select your microcontroller kit and get started... Fax a copy of From $295* RCM3400 this ad and receive a 5% discount on your order! Feature rich, compiler, editor & debugger with royalty free TCP/IP stack • Prices exclude GST and delivery charges. Tel: + 61 2 9906 6988 Fax: + 61 2 9906 7145 www.dominion.net.au 4007 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 catalog and price list. Eco Watch phone: (03) 9761 7040; fax: (03) 9761 7050; Unit 5, 17 Southfork Drive, Kilsyth, Vic. 3137. ABN 63 006 399 480. SUPERBRIGHT LEDS from just 8 cents each, including new wide angle range! 12 volt LED lightbars, great for solar/ camping. Nixie tubes and nixie kits. Lots of other stuff, and always more items being added. www.ledsales.com.au RCS RADIO/DESIGN is at 41 Arlewis St, Chester Hill 2162, NSW Australia siliconchip.com.au Do You Eat, Breathe and Sleep TECHNOLOGY? Opportunities for full-time and part-time positions all over Australia & New Zealand Jaycar Electronics is a rapidly growing, Australian owned, international retailer with more than 39 stores in Australia and New Zealand. Our aggressive expansion programme has resulted in the need for dedicated individuals to join our team to assist us in achieving our goals. We pride ourselves on the technical knowledge of our staff. Do you think that the following statements describe you? Please put a tick in the boxes that do: Knowledge of electronics, particularly at component level. Assemble projects or kits yourself for car, computer, audio, etc. Have empathy with others who have the same interest as you. May have worked in some retail already (not obligatory). Have energy, enthusiasm and a personality that enjoys helping people. Appreciates an opportunity for future advancement. Have an eye for detail. Why not do something you love and get paid for it? Please write or email us with your details, along with your C.V. and any qualifications you may have. We pay a competitive salary, sales commissions and have great benefits like a liberal staff purchase policy. Advertising Index 555 Electronics.............................51 Amateur Scientist CD ..............OBC Send to: Retail Operations Manager - Jaycar Electronics Pty Ltd P.O. Box 6424 Silverwater NSW 1811 Email: jobs<at>jaycar.com.au Altronics.......................................29 Jaycar Electronics is an equal opportunity employer and actively promotes staff from within the organisation. Dick Smith Electronics........... 16-21 Av-Comm...................................111 Dominion Electronics............81,110 Eco Watch..................................110 Elexol...........................................51 Satellite TV Reception ELNEC IC PROGRAMMERS Furzy Electronics........................110 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°. Universal and specialised models High quality Realistic prices Large range of adaptors Free regular software updates Windows 95/98/Me/NT/2k/XP Grantronics.................................111 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 GRANTRONICS PTY LTD PO Box 275, Wentworthville. 2145. Ph: 02 9896 7150 and has all the published PC boards from SC, EA, ETI, HE, AEM & others. Ph (02) 9738 0330. sales<at>rcsradio. com.au, www.rcsradio.com.au Full details on web-site. Credit cards accepted. GRANTRONICS PTY LTD, PO Box 275, Wentworthville 2145. (02) 9896 7150 or http://www.grantronics.com.au S-Video . . . Video . . . Audio . . . VGA distribution amps, splitters, standards converters, tbc’s, switchers, cables, etc, & price list: www.questronix.com.au ImageCraft C Compilers: 32-bit Windows IDE and compiler. For AVR, 68HC­08, 68HC11, 68HC12, 68HC16. from $330.00 Atmel Flash CPU Programmer: Handles the 89Cx051, 89C5x, 89Sxx in both DIP and PLCC44 and some AVR’s, most 8-pin EEPROMS. Includes socket for serial ISP cable. $220, $11 p&p. SOIC adaptors: 20 pin $132.00, 14 pin $126.50, 8 pin $121.00. www.grantronics.com.au PCBs MADE, ONE OR MANY. Any format, hobbyists welcome. Sesame Electronics Phone (02) 9593 1025. sesame<at>sesame.com.au www.sesame.com.au KIT ASSEMBLY NEVILLE WALKER KIT ASSEMBLY & REPAIR: • Australia wide service • Small production runs • Specialist “one-off” applications Phone Neville Walker (07) 3857 2752 Email: flashdog<at>optusnet.com.au Circuit & Design Ideas Wanted Do you have a good circuit idea? If so, sketch it out, write a brief description of its operation & send it to us. Provided your idea is workable & original, we’ll publish it in Circuit Notebook & you’ll make some money. We pay up to $60 for a good circuit so send your idea to: Silicon Chip Publications, PO Box 139, Collaroy, NSW 2097. siliconchip.com.au Harbuch Electronics...................100 Instant PCBs..............................110 Jaycar ...............IFC, 53-60,101,111 JED Microprocessors..............5,101 Microgram Computers....................3 Oatley Electronics........................93 Ocean Controls..........................109 Ozitronics.....................................81 Prime Electronics...........................7 Quest Electronics.........101,110,111 RCS Radio.................................110 RF Probes....................................95 SC Perf Elect. For Cars................72 Silicon Chip Binders..............73,110 Silicon Chip Bookshop........112,IFC Silicon Chip Subscriptions.........108 Silvertone Electronics................110 Siomar Batteries..........................69 Speakerbits................................110 Taig Machinery...........................110 Telelink.......................................101 VAF............................................103 ____________________________ PC Boards Printed circuit boards for SILICON CHIP projects are made by: RCS Radio Pty Ltd. Phone (02) 9738 0330. Fax (02) 9738 0334. August 2005  111 ALL S ILICON C HIP SUBSCRIBERS – PRINT, OR BOTH – AUTOMATICALLY QUALIFY FOR A REFERENCE $ave 10%ONLINE DISCOUNT ON ALL BOOK OR PARTSHOP PURCHASES. CHIP BOOKSHOP 10% (Does not apply to subscriptions) SILICON For the latest titles and information, please refer to our website books page: www.siliconchip.com.au/Shop/Books PIC MICROCONTROLLERS: know it all SELF ON AUDIO Multiple authors $85.00 The best of subjects Newnes authors have written over the past few years, combined in a one-stop maxi reference. Covers introduction to PICs and their programming in Assembly, PICBASIC, MBASIC & C. 900+ pages. PROGRAMMING and CUSTOMIZING THE PICAXE By David Lincoln (2nd Ed, 2011) $65.00* A great aid when wrestling with applications for the PICAXE See series of microcontrollers, at beginner, intermediate and Review April advanced levels. Every electronics class, school and library should have a copy, along with anyone who works with PICAXEs. 300 pages in paperback. 2011 PIC IN PRACTICE by D W Smith. 2nd Edition - published 2006 $60.00* Based on popular short courses on the PIC, for professionals, students and teachers. Can be used at a variety of levels. An ideal introduction to the world of microcontrollers. 255 pages in paperback. PIC MICROCONTROLLER – your personal introductory course By John Morton 3rd edition 2005. $60.00* A unique and practical guide to getting up and running with the PIC. It assumes no knowledge of microcontrollers – ideal introduction for students, teachers, technicians and electronics enthusiasts. Revised 3rd edition focuses entirely on re-programmable flash PICs such as 16F54, 16F84 12F508 and 12F675. 226 pages in paperback. by Douglas Self 2nd Edition 2006 $69.00* A collection of 35 classic magazine articles offering a dependable methodology for designing audio power amplifiers to improve performance at every point without significantly increasing cost. Includes compressors/limiters, hybrid bipolar/FET amps, electronic switching and more. 467 pages in paperback. SMALL SIGNAL AUDIO DESIGN By Douglas Self – First Edition 2010 $95.00* The latest from the Guru of audio. Explains audio concepts in easy-to-understand language with plenty of examples and reasoning. Inspiration for audio designers, superb background for audio enthusiasts and especially where it comes to component peculiarities and limitations. Expensive? Yes. Value for money? YES! Highly recommended. 558 pages in paperback. AUDIO POWER AMPLIFIER DESIGN HANDBOOK by Douglas Self – 5th Edition 2009 $85.00* "The Bible" on audio power amplifiers. Many revisions and updates to the previous edition and now has an extra three chapters covering Class XD, Power Amp Input Systems and Input Processing and Auxiliarly Subsystems. Not cheap and not a book for the beginner but if you want the best reference on Audio Power Amps, you want this one! 463 pages in paperback. DVD PLAYERS AND DRIVES by K.F. Ibrahim. Published 2003. $71.00* OP AMPS FOR EVERYONE By Bruce Carter – 4th Edition 2013 $83.00* This is the bible for anyone designing op amp circuits and you don't have to be an engineer to get the most out of it. It is written in simple language but gives lots of in-depth info, bridging the gap between the theoretical and the practical. 281 pages, A guide to DVD technology and applications, with particular focus on design issues and pitfalls, maintenance and repair. Ideal for engineers, technicians, students of consumer electronics and sales and installation staff. 319 pages in paperback. by Sanjaya Maniktala, Published April 2012. $83.00 Thoroughly revised! The most comprehensive study available of theoretical and practical aspects of controlling and measuring EMI in switching power supplies. Subtitled Exploring the PIC32, a Microchip insider tells all on this powerful PIC! Focuses on examples and exercises that show how to solve common, real-world design problems quickly. Includes handy checklists. FREE CD-ROM includes source code in C, the Microchip C30 compiler, and MPLAB SIM. 400 pages paperback. By Garry Cratt – Latest (7th) Edition 2008 $49.00 Written in Australia, for Australian conditions by one of Australia's foremost satellite TV experts. If there is anything you wanted to know about setting up a satellite TV system, (including what you can't do!) it's sure to be covered in this 176-page paperback book. See Review Feb 2004 SWITCHING POWER SUPPLIES A-Z PROGRAMMING 32-bit MICROCONTROLLERS IN C By Luci di Jasio (2008) $79.00* PRACTICAL GUIDE TO SATELLITE TV See Review March 2010 ELECTRIC MOTORS AND DRIVES By Austin Hughes & Bill Drury - 4th edition 2013 $59.00* This is a very easy to read book with very little mathematics or formulas. It covers the basics of all the main motor types, DC permanent magnet and wound field, AC induction and steppers and gives a very good description of how speed control circuits work with these motors. Soft covers, 444 pages. NEWNES GUIDE TO TV & VIDEO TECHNOLOGY By KF Ibrahim 4th Edition (Published 2007) $49.00 It's back! Provides a full and comprehensive coverage of video and television technology including HDTV and DVD. Starts with fundamentals so is ideal for students but covers in-depth technologies such as Blu-ray, DLP, Digital TV, etc so is also perfect for engineers. 600+ pages in paperback. RF CIRCUIT DESIGN by Chris Bowick, Second Edition, 2008. $63.00* The classic RF circuit design book. RF circuit design is now more important that ever in the wireless world. In most of the wireless devices that we use there is an RF component – this book tells how to design and integrate in a very practical fashion. 244 pages in paperback. PRACTICAL RF HANDBOOK AC MACHINES By Jim Lowe Published 2006 $66.00* Applicable to Australian trades-level courses including NE10 AC Machines, NE12 Synchronous Machines and the AC part of NE30 Electric Motor Control and Protection. Covering polyphase induction motors, singlephase motors, synchronous machines and polyphase motor starting. 160 pages in paperback. PRACTICAL VARIABLE SPEED DRIVES & POWER ELECTRONICS Se e by Malcolm Barnes. 1st Ed, Feb 2003. $73.00* Review An essential reference for engineers and anyone who wishes to design or use variable speed drives for induction motors. 286 pages in soft cover. Feb 2003 BUILD YOUR OWN ELECTRIC MOTORCYCLE by Carl Vogel. Published 2009. $40.00* by Ian Hickman. 4th edition 2007 $61.00* Alternative fuel expert Carl Vogel gives you a hands-on guide with A guide to RF design for engineers, technicians, students and enthusiasts. the latest technical information and easy-to-follow instructions Covers key topics in RF: analog design principles, transmission lines, for building a two-wheeled electric vehicle – from a streamlined couplers, transformers, amplifiers, oscillators, modulation, transmitters and scooter to a full-sized motorcycle. 384 pages in soft cover. receivers, propagation and antennas. 279 pages in paperback. *NOTE: ALL PRICES ARE PLUS P&P – AUSTRALIA ONLY: $10.00 per order; NZ – $AU12.00 PER BOOK; REST OF WORLD $AU18.00 PER BOOK To Place Your Order: INTERNET (24/7) PAYPAL (24/7) eMAIL (24/7) www.siliconchip. com.au/Shop/Books Use your PayPal account silicon<at>siliconchip.com.au silicon<at>siliconchip.com.au with order & credit card details FAX (24/7) MAIL (24/7) Your order and card details to Your order to PO Box 139 Collaroy NSW 2097 (02) 9939 2648 with all details PHONE – (9-5, Mon-Fri) Call (02) 9939 3295 with with order & credit card details You can also order and pay for books by cheque/money order (Mail Only). Make cheques payable to Silicon Chip Publications. ALL TITLES SUBJECT TO AVAILABILITY. PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. ALL PRICES INCLUDE GST ALL S ILICON C HIP SUBSCRIBERS – PRINT, OR BOTH – AUTOMATICALLY QUALIFY FOR A REFERENCE $ave 10%ONLINE DISCOUNT ON ALL BOOK OR PARTSHOP PURCHASES. CHIP BOOKSHOP 10% (Does not apply to subscriptions) SILICON For the latest titles and information, please refer to our website books page: www.siliconchip.com.au/Shop/Books PIC MICROCONTROLLERS: know it all SELF ON AUDIO Multiple authors $85.00 The best of subjects Newnes authors have written over the past few years, combined in a one-stop maxi reference. Covers introduction to PICs and their programming in Assembly, PICBASIC, MBASIC & C. 900+ pages. PROGRAMMING and CUSTOMIZING THE PICAXE By David Lincoln (2nd Ed, 2011) $65.00* A great aid when wrestling with applications for the PICAXE See series of microcontrollers, at beginner, intermediate and Review April advanced levels. Every electronics class, school and library should have a copy, along with anyone who works with PICAXEs. 300 pages in paperback. 2011 PIC IN PRACTICE by D W Smith. 2nd Edition - published 2006 $60.00* Based on popular short courses on the PIC, for professionals, students and teachers. Can be used at a variety of levels. An ideal introduction to the world of microcontrollers. 255 pages in paperback. PIC MICROCONTROLLER – your personal introductory course By John Morton 3rd edition 2005. $60.00* A unique and practical guide to getting up and running with the PIC. It assumes no knowledge of microcontrollers – ideal introduction for students, teachers, technicians and electronics enthusiasts. Revised 3rd edition focuses entirely on re-programmable flash PICs such as 16F54, 16F84 12F508 and 12F675. 226 pages in paperback. by Douglas Self 2nd Edition 2006 $69.00* A collection of 35 classic magazine articles offering a dependable methodology for designing audio power amplifiers to improve performance at every point without significantly increasing cost. Includes compressors/limiters, hybrid bipolar/FET amps, electronic switching and more. 467 pages in paperback. SMALL SIGNAL AUDIO DESIGN By Douglas Self – First Edition 2010 $95.00* The latest from the Guru of audio. Explains audio concepts in easy-to-understand language with plenty of examples and reasoning. Inspiration for audio designers, superb background for audio enthusiasts and especially where it comes to component peculiarities and limitations. Expensive? Yes. Value for money? YES! Highly recommended. 558 pages in paperback. AUDIO POWER AMPLIFIER DESIGN HANDBOOK by Douglas Self – 5th Edition 2009 $85.00* "The Bible" on audio power amplifiers. Many revisions and updates to the previous edition and now has an extra three chapters covering Class XD, Power Amp Input Systems and Input Processing and Auxiliarly Subsystems. Not cheap and not a book for the beginner but if you want the best reference on Audio Power Amps, you want this one! 463 pages in paperback. DVD PLAYERS AND DRIVES by K.F. Ibrahim. Published 2003. $71.00* OP AMPS FOR EVERYONE By Bruce Carter – 4th Edition 2013 $83.00* This is the bible for anyone designing op amp circuits and you don't have to be an engineer to get the most out of it. It is written in simple language but gives lots of in-depth info, bridging the gap between the theoretical and the practical. 281 pages, A guide to DVD technology and applications, with particular focus on design issues and pitfalls, maintenance and repair. Ideal for engineers, technicians, students of consumer electronics and sales and installation staff. 319 pages in paperback. by Sanjaya Maniktala, Published April 2012. $83.00 Thoroughly revised! The most comprehensive study available of theoretical and practical aspects of controlling and measuring EMI in switching power supplies. Subtitled Exploring the PIC32, a Microchip insider tells all on this powerful PIC! Focuses on examples and exercises that show how to solve common, real-world design problems quickly. Includes handy checklists. FREE CD-ROM includes source code in C, the Microchip C30 compiler, and MPLAB SIM. 400 pages paperback. By Garry Cratt – Latest (7th) Edition 2008 $49.00 Written in Australia, for Australian conditions by one of Australia's foremost satellite TV experts. If there is anything you wanted to know about setting up a satellite TV system, (including what you can't do!) it's sure to be covered in this 176-page paperback book. See Review Feb 2004 SWITCHING POWER SUPPLIES A-Z PROGRAMMING 32-bit MICROCONTROLLERS IN C By Luci di Jasio (2008) $79.00* PRACTICAL GUIDE TO SATELLITE TV See Review March 2010 ELECTRIC MOTORS AND DRIVES By Austin Hughes & Bill Drury - 4th edition 2013 $59.00* This is a very easy to read book with very little mathematics or formulas. It covers the basics of all the main motor types, DC permanent magnet and wound field, AC induction and steppers and gives a very good description of how speed control circuits work with these motors. Soft covers, 444 pages. NEWNES GUIDE TO TV & VIDEO TECHNOLOGY By KF Ibrahim 4th Edition (Published 2007) $49.00 It's back! Provides a full and comprehensive coverage of video and television technology including HDTV and DVD. Starts with fundamentals so is ideal for students but covers in-depth technologies such as Blu-ray, DLP, Digital TV, etc so is also perfect for engineers. 600+ pages in paperback. RF CIRCUIT DESIGN by Chris Bowick, Second Edition, 2008. $63.00* The classic RF circuit design book. RF circuit design is now more important that ever in the wireless world. In most of the wireless devices that we use there is an RF component – this book tells how to design and integrate in a very practical fashion. 244 pages in paperback. PRACTICAL RF HANDBOOK AC MACHINES By Jim Lowe Published 2006 $66.00* Applicable to Australian trades-level courses including NE10 AC Machines, NE12 Synchronous Machines and the AC part of NE30 Electric Motor Control and Protection. Covering polyphase induction motors, singlephase motors, synchronous machines and polyphase motor starting. 160 pages in paperback. PRACTICAL VARIABLE SPEED DRIVES & POWER ELECTRONICS Se e by Malcolm Barnes. 1st Ed, Feb 2003. $73.00* Review An essential reference for engineers and anyone who wishes to design or use variable speed drives for induction motors. 286 pages in soft cover. Feb 2003 BUILD YOUR OWN ELECTRIC MOTORCYCLE by Carl Vogel. Published 2009. $40.00* by Ian Hickman. 4th edition 2007 $61.00* Alternative fuel expert Carl Vogel gives you a hands-on guide with A guide to RF design for engineers, technicians, students and enthusiasts. the latest technical information and easy-to-follow instructions Covers key topics in RF: analog design principles, transmission lines, for building a two-wheeled electric vehicle – from a streamlined couplers, transformers, amplifiers, oscillators, modulation, transmitters and scooter to a full-sized motorcycle. 384 pages in soft cover. receivers, propagation and antennas. 279 pages in paperback. *NOTE: ALL PRICES ARE PLUS P&P – AUSTRALIA ONLY: $10.00 per order; NZ – $AU12.00 PER BOOK; REST OF WORLD $AU18.00 PER BOOK To Place Your Order: INTERNET (24/7) PAYPAL (24/7) eMAIL (24/7) www.siliconchip. com.au/Shop/Books Use your PayPal account silicon<at>siliconchip.com.au silicon<at>siliconchip.com.au with order & credit card details FAX (24/7) MAIL (24/7) Your order and card details to Your order to PO Box 139 Collaroy NSW 2097 (02) 9939 2648 with all details PHONE – (9-5, Mon-Fri) Call (02) 9939 3295 with with order & credit card details You can also order and pay for books by cheque/money order (Mail Only). Make cheques payable to Silicon Chip Publications. ALL TITLES SUBJECT TO AVAILABILITY. PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. ALL PRICES INCLUDE GST