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Christmas Wishlist HAVE FUN THIS SUMMER SEA SCOOTER MKII REMOTE CONTROL The new and improved scooter that's been designed specifically for family fun in the pool, lake or protected beaches. The powerful 130 watt motor can reach a maximum speed of 5km/h and is powered by a rechargeable battery which gives around 40 - 50 mins running time. It's lightweight and includes sports carry bag - perfect for the kids to take on your next riverside picnic. It's easy to manoeuvre and control with finger-tip controls on the handlebars $ and can even be used for shallow snorkelling. • Powered by 12V 12Ah battery (battery included) • Up to 1 hour use time or 40min continuous • Thrust: 5kgf • Speed: 5kmh NEW & D E IMPROV INFRARED DIGITAL PEN & NOTETAKER Clip this handy bit to any A4 piece of paper, start writing or drawing and everything you enter will be captured electronically and stored in your computer. As portable handwriting capture device, it has two modes of operation: Mobile mode allows you to take and store notes while away from your computer in meetings, lectures or conferences. In Online mode, you use it like a tablet PC connected to your USB port. Includes Notes Manager software so you can edit, e-mail and organise your notes, drawings and Sketches. Ideal for students or in the office. • Full mouse functionality when working online • Standard off-the-shelf ink refills $ 165 Cat: XC-0355 REMOTE CONTROL OFF-ROAD VEHICLES ATTENTION RC HOBBYISTS... Don't be fooled by the price tag, these are serious 1/10th scale electric off-road remote control racing cars! Each is constructed around a lightweight hardened plastic chassis, and features front and rear fully adjustable independent suspension with oildampened shock absorbers, full-time shaft-driven 4WD with front and rear geared differentials, lightweight aluminium top plate for extra chassis strength, hi-speed steering servo, electronic speed controller (ESC) and hi-torque RC540 brushed motor. Recommended for ages 12 yrs + 1/10th Electric Racing Buggy GT-3670 $219 1/10th Electric Monster Truck GT-3672 $239 GT-3672 249 DOGFIGHTING CHOPPERS Create your own dogfight with this pair of battling helicopter gunships. Each is equipped with a 280-round IR 'gun' to blow your opponent away. When you register a hit, your enemy's chopper falls out of the sky until revived. 20 minutes charge gives about 8 minutes flight time. Safe for indoor use. Each is approx. 170mm long • Suitable for ages 8yrs+ • Requires 6 x AA batteries • Sold as a pair $ 69 95 Cat: GT-3216 Cat: GG-2350 REMOTE CONTROL UFO HELICOPTER All I Want for Christmas is at This slightly weird machine generates a very stable and high flight with its wide rotors. It is made of durable foam which will handle a few knocks from those unexperienced landings and armchair pilots. 20 minute charge via the remote unit provides about 8 minutes of flying time. • Requires 6 x AA batteries $ 95 • Wingspan: 310mm Cat: GT-3276 • Suitable for ages 8yrs+ 44 USB OPTICAL MOUSE WITH NUMBER KEYPAD ACTIVE SPEAKERS YOUR FOR IPOD® Dock your iPod® and be free of wires. Perfect while travelling, at your desk or even in the kitchen while doing the dishes. The 4 speakers produce a high quality sound that won't disappoint. You can connect it to CD players, computers or any audio emitting device with a 3.5mm socket. • Lead length 700mm • Measures: 67(W) x 110(L) x 20(H)mm Note: iPod® not included $ Notebook computers are great when you are ving about or space is at a premium. However, the lack of a proper numeric keypad and mouse can be a real nuisance. This problem is easily fixed with this new combination USB keypad and mouse. It simply plugs into the computer's USB port and gives you a full function numeric keypad and mouse. 74 95 $ Cat: XC-5179 32 95 Cat: XC-5138 REMOTE COMMAND-A-MAN Is your man a fat slob who sits on his bum all day watching the footy and sinking tinnies? Wait no more ladies! Use your remote to take control of the slob. All the functions you need are right at your fingertips - Talk About Shopping, Shoes, Need Flowers/Chocolate/Massage etc. It also has a function for putting the toilet seat down, but we're fairly sure it doesn't work technology can only do so much. REMOTE COMMAND-A-WOMAN Finally someone has decided to put technology to a worthwhile use. Just point the remote at the subject and select one of nine functions: Cook, Clean, Remove Clothes, Say Yes, Leave etc. It also has a Dial-up Breast Enhancer/reducer and a Hurry Up function for when you want her to get a move on so you can get to the footy. • 3 stop functions: Snoring, Farting, Belching • No batteries required powered by mind control $ 9 95 Cat: GT-3170 GT-3670 • Three stop functions - nagging, whingeing, moaning • No batteries required powered by chauvinism. • Requires an IQ of at least 10 to operate. $ 9 95 Cat: GT-3172 Prices valid to 31st December 2008 Free Call: 1800 022 888 for orders! www.jaycar.com.au Contents Vol.21, No.12; December 2008 www.siliconchip.com.au SILICON CHIP Features 12 The Chevrolet Volt Electric Car The star of this year’s Sydney Motor Show, the Chevrolet Volt is a true electric vehicle. Here’s a look at the technology behind the vehicle – by Ross Tester 18 Digital Cinema: Digitising The Movies There’s a revolution in the movie industry, with the industry slowly moving away from film to digital. There are advantages for production, distribution and even copyright protection – by Barrie Smith 68 Review: Owon Digital Hand-Held Oscilloscope We look at Owon’s affordable dual-channel digital oscilloscope that can also double as a digital multimeter. Its portability makes it ideal for field work – by Mauro Grassi Chevrolet Volt Electric Car – Page 12. 78 The 2008 AEVA Electric Vehicle Field Day An interesting display of DIY electric vehicle conversions – by Leo Simpson Pro jects To Build 28 Versatile Car Scrolling Display, Pt.1 Use it to monitor, display and log up to six sensors on a scrolling or static LED display. You program it via the USB port & it can also control two relay outputs in response to measured signals – by Mauro Grassi 36 Test The Salt Content Of Your Swimming Pool Don’t shell out big bucks for a salt-water tester for your pool. Our low-tech solution is easy to set up and costs almost nothing – by Leo Simpson Versatile Car Scrolling Display & Data Logger – Page 28. 60 Build A Brownout Protector Low mains voltages (brownouts) are a fatal hazard to induction motors. This Brownout Protector is rated at 2300W and is easy to build – by John Clarke 72 Simple Voltage Switch For Car Sensors Use it to monitor a car sensor and turn things on and off . . . boost solenoids, fans, water injection, intercooler sprays, etc – design by John Clarke Special Columns 40 Serviceman’s Log Intermittents: No Money For Old Rope – by the TV Serviceman 53 Circuit Notebook (1) Fuzz Box For Guitars; (2) Monitor For Pet Bed Heater; (3) One-Button Camera Timer; (4) VHF Aircraft Receiver With Squelch; (5) Toy Poker Machine Is No Risk To Wallet; (6) Battery Monitor Has Low Current Drain Build A Brownout Protector – Page 60. 82 Vintage Radio The Leak TL/12 Plus Valve Amplifier – by Rodney Champness Departments 2   4 17 39 Publisher’s Letter Mailbag Book Review Product Showcase siliconchip.com.au 77 87 90 94 Order Form Ask Silicon Chip Notes & Errata Market Centre Simple Voltage Switch For Car Sensors – Page 72. December December 2008  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 John Clarke, B.E.(Elec.) Technical Staff Ross Tester Jim Rowe, B.A., B.Sc, VK2ZLO Mauro Grassi, B.Sc. (Hons), Ph.D Photography Ross Tester Reader Services Ann Morris Advertising Enquiries Glyn Smith Phone (02) 9939 3295 Mobile 0431 792 293 glyn<at>siliconchip.com.au Regular Contributors Brendan Akhurst Rodney Champness, VK3UG 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: $89.50 per year in Australia. For overseas rates, see the order form in this issue. Editorial office: Unit 1, 234 Harbord Rd, Brookvale, NSW 2100. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 9939 3295. Fax (02) 9939 2648. E-mail: silicon<at>siliconchip.com.au ISSN 1030-2662 * Recommended and maximum price only. 2  Silicon Chip Publisher’s Letter Electric vehicles might be a technological dead-end This month we have two reports on electric vehicles. The first, on the General Motors’ Chevy Volt, is about a state-of-the-art electric vehicle which is slated to go into production in two years’ time. The second, our report on the AEVA field day at Rouse Hill in Sydney during October, shows developments at the do-it-yourself end of the electric vehicle scene. Neither report really gives many clues as to what sorts of cars we will be driving in 10 years’ time or further into the future. For a start, the majority of the cars we are driving right now will probably still be on the road in 10 years’ time. Second, it is by no means certain that the prototype electric cars presently being touted by the major car manufacturers will go into production in their present form. In fact, it is by no means certain that General Motors in the USA will even survive their current financial woes without substantial government assistance and restructuring. In any case, if it does ahead, it appears as though the motor and batteries finally employed in the Chevy Volt could be quite different to the concept car seen at the Sydney Motor show. We have also stated in a past issue that we thought the Chevy Volt was a “pretend electric car” in that it has fairly limited battery capacity and a small internal combustion engine to provide long range trip capacity. Given that GM has prior experience in producing the ill-fated EV-1, you would think they would take a better approach. Or is it because car dealers can see that electric cars will require little after-sales service and there won’t be much money to be made from a pure electric vehicle? What does seem certain is that more hybrid electric cars will be available in years to come. Toyota’s Prius and the Lexus hybrid range of cars have already been a big sales success and you can expect more of the same from Toyota, Honda and the other Japanese manufacturers. There is even a Commodore hybrid planned for release in a year or so. However, it must be said that none of the existing hybrids from Toyota or Honda really push the envelope in getting the really high fuel economy which is potentially available. Already, the Toyota Prius has been modified by DIY enthusiasts to get claimed economy down below 2.5l/100km. How much better could it be if Toyota pushed the technology as far as it could? The good news is that diesel hybrids being developed by some of the European car manufacturers (eg, the VW TwinDrive) are planned to do much better and will have an electric only range of 50km or more, comparable with the Chevy Volt. But just because hybrid electric vehicles may seem more practical at the moment, this does not mean that particular technology will necessarily dominate in the long term. Other hybrid vehicles could take the spot-light. What do I mean by that? At present there is quite a lot of research into diesel hybrid vehicles with hydrostatic transmissions – no electric motors would be involved. If that seems outlandish, consider that the vast majority of earth-moving vehicles, from the humble Bobcat right up to huge mining machines, use hydrostatic transmissions. They run at very high hydraulic pressures (typically 21,000kPa or 3000 psi) and they use a hydraulic accumulator which is driven by a relatively small diesel engine working at more or less constant load. Furthermore, a vehicle with a hydrostatic transmission can provide very effective regenerative braking – much more effective than electric motor regeneration. Another big advantage of a diesel hydrostatic vehicle is that it does not have a large investment in batteries which have long-term consequences for the environment. In reality, such vehicles would not represent a drastic change from technology available right now. So what sort of vehicle are you likely to be driving in 10 or 15 years’ time? It might be a diesel hydrostatic. Leo Simpson siliconchip.com.au Whether you need a robot for research, an educational robot or just a robot to have some fun with then we have a robot to suit your needs. Tribotix’s custom designed Robots and electronics …. Tribotix are now developing our own robots and associated processing systems. HyKim, a 21DOF robot bear, is one of the worlds most advanced commercially available robots. HyKim 21 DOF Robot Bear HyInt is the powerful processing system used within HyKim. HyInt is based around a 500MHz AMD Geode processor that can communicate at 1Mbps with Robotis’s range of Dynamixel modules. This allows HyInt to be used as the main processing system in any Dynamixel based robot. Robotis CycloidII with HyInt fitted. Featured product …. RoboBuilder wCK modules & Robot Kits RoboBuilder have created a fantastic robot kit based are around their highly configurable wCK range of serially controlled servo modules. RoboBuilder’s Creator Kits are now compatible with Microsoft Robotic Studio (MSRS). The wCK modules are unique, not only can the PID characteristics of each module be adjusted, but each wCK module has 2 Analog outputs and 1 Digital Input. 5710K Creator Kit (18wCK modules) The wCK modules can also be programmed to perform simple sequences, without the need for a host mcu. The wCK modules are well worth considering for your next project. Other products we supply .... CoroWare POB Technologies Robotis KumoTek Kondo Mention this add and receive free shipping within Australia for all orders placed before 25/12/08. Tribotix Pty Ltd • ABN 23 108 604 226 p:+61 2 49578255 • f:+61 2 49578244 e:info<at>tribotix.com • w:www.tribotix.com MAILBAG Letters and emails should contain complete name, address and daytime phone number. Letters to the Editor are submitted on the condition that Silicon Chip Publications Pty Ltd may edit and has the right to reproduce in electronic form and communicate these letters. This also applies to submissions to “Ask SILICON CHIP” and “Circuit Notebook”. HDTV is a sick joke I could not agree more that HD Tele­ vision is being wasted in this country (Publisher’s Letter, September 2008). I am sure that I am not the only one who is fed up with the unprofessionalism of our so-called “free-to-air” networks. I note that there is still no HD programming in any newspaper guides. The people who print the guides probably have good reason though, when you consider that the networks consistently change programs at the last minute, making guides useless anyway. The networks can’t even get their own EPGs right half the time, so what chance do we have? The Government does not appear to give a toss about this appalling situation. It will continue unless people get off their butts and demand change. If not, HDTV will go nowhere as the networks will only put in the minimum money and time that they need to. The Government is going to cop a Smart power meters do not jack up your electricity bill I read with interest your Publisher’s Letter on smart power meters (October 2008) and would like to provide you with some “real world” figures as your assumption of usage patterns did not reflect my actual case. The EnergyAustralia bill now shows the three usage periods as a percentage. I have recorded and graphed my usage on an Excel spreadsheet since having a smart power meter installed in June 2007. I have diligently recorded the power bill details for the past four quarters. The spreadsheet also compares the costs had I not installed the smart meter (equivalent flat rate costs). All four periods have shown a saving by going to smart metering. I also live in a relatively mild part of Sydney (Wahroonga) but do have a 4  Silicon Chip beating if they don’t wake up. When they switch the analog system off we will be left with a substandard service and they are the ones that will pay the price of voter anger. Tony Joyce, Macquarie Fields, NSW. Return shot on fuel consumption conversion As one who has supposedly “shot himself in the foot” (Mailbag, September 2008, page 4), I would like to make a further comment. While I concur that Allan Hornsby has performed the maths correctly, 81 litres is the absolute minimum quantity of fuel required. To make the maths simple, I rounded the figure up to 100 litres; the additional 19 litres is my reserve. Perhaps I should have been more explicit in my previous letter on the subject. It is highly unlikely that either a journey would be exactly 900km or that the fuel consumption be exactly reverse-cycle air conditioner which is generally just used for heating. We have an electric oven and cooktop, LCD television, three computers that are permanently powered (web hosting, email and network storage), two fish tanks, dishwasher, washing machine and drier as well as a large swimming pool. There are four adults living in the house. Hot water is provided by instantaneous gas. We have a mix of halogen, incandescent and compact fluorescent lights. We generally try to use the power hungry appliances (drier, dishwasher, pool pump) outside the peak period and use “old sol” for drying clothes. The pool pump timer is set to run from 8.00am to 1:45pm on weekdays and from 9.00am to 3.00pm on the weekend. Steve Wright, Wahroonga, NSW. 9L/100km! The aim was to show how simple it was to use the “fuel consumption” figure. If either mpg or km/L values are used then the more difficult division process is required (900 divided by 11 [approx.]). If Allan fills up with exactly 81 litres for his journey, then I foresee him walking with “can in hand” to the nearest fuel outlet. Ray Smith, Hoppers Crossing, Vic. Ceramic filters can be obtained from a junked TV In response to the question about ceramic filters for the Jupiter receiver (SILICON CHIP, August 2008) on page 100 of the October issue, F. A. is mistaken in that they are not described as “ceramic resonators”. A ceramic resonator can be a two or 3-legged device which is commonly found in the clock generator on many microprocessorbased circuits. A ceramic filter differs in the fact that it can be either a narrowband filter which will trap all frequencies and pass only the wanted frequency or a notch filter which will do just the opposite. I am not sure in which country F. A. is based but a ready source of these filters is from the sound IF section in a defunct VCR or TV which will be either 5.5MHz (Aus/NZ) or 6.0MHz (South Africa/UK). Another supplier is Trade Tech New Zealand which has them: http://www.tradetech.co.nz/ results.html?search_type=1&new_ search=1&q=cer5m5 Chris Jowsey, Hamilton, NZ. Power use can be greatly reduced You make a good case for the “Smart Power” charges increasing power bills by up to 45% (Publisher’s Letter, October 2008). In Victoria, no such proposal has been made (as yet) but I will be on the lookout when it does change. siliconchip.com.au EnergyAustralia comments on Smart Power Meters I write in response to your editorial on smart meters “Smart Meters Will Jack Up Your Electricity Bill” (October 2008). Smart meters are a new way of measuring electricity that give customers more control over their electricity costs. They allow electricity to be measured in 30-minute periods. This means that different rates can be charged for different time periods. This is known as time-based pricing. Under time-based pricing, we separate the day into three periods: shoulder, peak and off-peak. You get charged a lot less for the electricity you use during the off-peak, a little bit less for the shoulder and more during the peak. EnergyAustralia has been rolling out smart meters since 2003 and there are now more than 160,000 customers being billed on time-based rates. Recent analysis by EnergyAustralia of 32,000 household electricity accounts already using time-based billing found that families were saving on average $64 a year compared to traditional rates. About 70% of those customers were better off under time-based pricing and 71% of customers surveyed said it was a fairer pricing system. For those customers that paid more, 62% were Looking at your bill, I was surprised that with all your power conservation measures, you still used 1674kWh in 90 days. That’s 18.6kWh/day or equivalent to 775 watts continuously. Where is it all going? As a comparison, during a 3-month period from March to May in Melbourne we used 11.2kWh/day for two people. That is equivalent to 467W continuously. We do have a 50-inch plasma TV that drags 350W when on and 30W when off! It runs for about five hours per day which is 2.3kWh per day or 20% of our power usage! For the remaining 9kWh/day, I can only account for about 6 kWh/day, so I need to investigate the other 3kWh/day. I suspect it is coming from the “phantom power” from plugpacks, set-top boxes, siliconchip.com.au paying less than $20 a year more. We also found that on average, families were using 78% of power outside peak times. There is no peak time on weekends or public holidays so overall electricity costs are cheaper for 82% of the time. Under our time-based pricing structure, the vast majority of customers are saving money – that is a fact. If you are paying more, you have the chance to make a few small changes to save money. Here are some examples: (1) Switch your pool pump from peak to off-peak times and save over $250 a year; (2) Use your dishwasher after 10pm, rather than 7pm and save over $50 a year; (3) Use your clothes dryer after 8pm rather than 6pm and save over $40 a year. Note: off-peak hot water circuits do not change with smart meters. We are installing these meters to make our electricity network more efficient, give customers greater choice and help make people more aware of their energy use. Any customer having difficulties adjusting to these new rates can contact us on 13 15 35 to get more advice on how to save with their smart meter. Paul Topfer, Executive Manager Advanced Metering, EnergyAustralia, Sydney, NSW. amplifier, etc. I am in the process of checking this out. Measures I have taken to reduce power usage include: (1) Banned electric heating in favour of gas; (2) Replaced all tungsten lights with CFL or strip fluorescent tubes; (3) Replaced the ballast in the mostused kitchen strip fluorescent with an electronic one as choke ballasts are notoriously inefficient, using 10-20W; (4) Avoid re-heating food in the oven in favour of a microwave. For items like pies that get soggy in the microwave we have a small “pie oven” which heats up quickly; (5) Turn off all computers when not in use. I use “hibernate” on shut-down as it is faster to turn off and restart; (6) Cooling in summer is by evapora- 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 outputs, 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 December 2008  5 Mailbag: continued Choosing qood-quality automotive fuses The Serviceman had an interesting article about AG3 fuses earlier this year and hereby unfolds a little known fact about automotive fuses. Top of the line automotive electricians stock fuses which have the fuse material soldered to the end caps which are made of chrome plated brass. These are not cheap! Everybody else wants to sell you fuses which are made of chromeplated steel which are quite cheap and which quite often have the fuse material crimped between the end cap and the glass tube. If you happen to live in a warm climate with low humidity these will not give much of a problem. However, I live in a climate where the ambient tive air-conditioner rather than via a reverse-cycle air conditioner. This works well in Melbourne which has a dry heat but may not work in Sydney or Brisbane. This uses only about 20% of the power of an R/C air-conditioner. Unfortunately, it uses about 100L/hr of water, so I have installed 15,000 litres of water storage to offset water usage. (7) Solar power – in June, I installed 1kW of grid-connected solar power which cost $13,000 less the $8000 federal rebate. In winter it generated 1.8kWh/day on average. In September it generated 4kWh/day and I expect it to generate over 5kWh/day in summer. This measure alone has reduced my mains consumption in September to less than 8kWh/day. Between June and September the system generated 924kWh and fed 91kWh back to the grid. From January 2009, the Victorian state government has mandated that the supply utility has to pay me $0.60 per kWh fed back to the grid. (8) Wind power – I installed a small 500W wind turbine but unfortunately due to wind shading from a large tree, this project has been a flop, so I have 6  Silicon Chip temperature drops below 0°C quite frequently in winter. What happens when the frost starts to thaw is that a thin film of water is deposited on the outside of the fuse (and anything else which exhibits thermal inertia) due to dew point temperature change and over time this breaks through the chrome coating on the end caps and produces rust. This eventually gives an intermittent contact and finally fails, as it becomes open circuit. So next time you venture forth to buy automotive AG3 fuses take a small magnet with you. If the fuses fail to stick to it you have the good quality ones which will last a very long time unless you overstress them. Steer clear of the others. John Hardisty, Burnie, Tas. to move it. The local council has now asked me to get a planning permit, which is now in progress. If I can get clear air I may be able to connect the generator to the grid as well. Peter Kay, Dromana, Vic. Comment: a good deal of the high power consumption quoted in the Publisher’s Letter would be due to electric heating during August when it was quite cold in Sydney. The other main use would be the 2-door frost-free refrigerator. Standard definition TV gives a good picture I am wondering why your Publisher’s Letter in the March 2008 issue, on digital TV, was almost scathing of Standard Definition. SD produces a very acceptable picture which is capable of being as good as DVD video quality. The editorial tends to suggest that SD will not be the way of the future. HDTV takes up much more bandwidth (approximately four times SD) and as our broadcast TV bandwidth is a finite resource, I am sure that the regulators/broadcasters will continue to favour the current mix of one HD “channel” and several SD “channels” derived from a standard 7MHz of RF bandwidth allocation. Many viewers will not notice the improved quality of HD over SD and will not want to upgrade their display devices to get it so will be very happy to stay with SD. I do agree, however, that anybody contemplating the purchase of a STB should now only consider an HD version to ensure reception of all available programs but with PVRs there is still quite a price difference between SD and HD models. I live in a hilly area which gives TV reception problems but in every case, STBs have given a dramatic improvement without ever having to replace the original antenna. The April 2008 article on “digital” antennas gives very good guidance for an optimum installation but I would encourage readers to try an STB on their existing antenna system before just automatically replacing it. In June 2008, you ran a query on recording subtitles. Despite the response that says that VCRs cannot record teletext, I do have a VHS recorder (JVC model HR–S5990AM) that does capture the teletext and allows the captions (or even the full weather/ news suite being transmitted at the time of the recording if it is on the 7 network) to be optionally selected on the TV during tape playback. This function is extremely rare in a VCR and I do recall an outcry in the hearing-impaired community a few years back when the “only” machine on the market (a Northern European model) was withdrawn. The response also included the explanation that teletext needs a greater bandwidth than a VCR normally handles and as mine is a Super VHS machine, its extra video bandwidth must make the difference. It even manages it with standard tapes which it “over-drives”. Interestingly the manufacturer did not list this ability to support teletext/ subtitles as a feature. Without access to such a VCR, the next easiest/cheapest option is to select the teletext page 801 on an STB and then record its AV output via the AV input of a VCR but this does mean that the subtitles are permanently part of the video signal and cannot be optionally (de)selected during playback. siliconchip.com.au Timer recording is also a bit complicated with this option. The best solution is with a PVR but you need to be aware that some of the more basic models (DigiCrystal/SuperNet/Wintel) do not allow the menu selection of teletext during playback, but it is usually in the (analog) video stream sent to the TV and can be selected in the normal way on the TV. Graham Goeby, Greensborough, Vic. HOPERF 12V connector polarity is not standardised D. J. (Mailbag, October 2008) suggests that there are no suitable connectors for low-voltage amateur radio and similar equipment. However, the polarised 2-pin connectors originally used for 32V equipment are still available from Dick Smith Electronics. These connectors are rated at 32V 15A (or 45A at 12V) and are similar in size to the 240V 3-pin plugs and sockets, hence they are just as rugged. As for the polarity, there are two schools of thought. I remember the equivalent of the 3-pin earth pin being negative with the single pin at the top of the “T” being the positive pin when used for 32V. More recently, WICEN in Victoria and perhaps other states chose the horizontal pin at the top of the “T” to be negative – because it looked like a minus sign if the plug was held with it at the top. However, if the plug was rotated through 90°, the other pin then looked like the minus sign. Searching the Internet does not find a winner, one way or the other. Either way, the polarity should be marked clearly. Ken Jobling, Carlton, Vic. Very low speed motor from microwave oven Regarding B. I.’s need for a slowturning motor to allow epoxy to dry evenly on fishing rods (Ask SILICON CHIP, November 2008), my suggestion, being a tightwad from way back, would be to scrounge the turntable motor from a discarded microwave. A piece of plastic tube over the drive becomes the start of a “chuck” that can support one end of the rod. These motors are invariably NOT double-insulated so siliconchip.com.au Digital Sensors RF IC & Modules Semiconductor Devices SAW Devices Distributed in Australia by Microzed Computers Pty. Limited Phone: 1300 735 420 Fax: 1300 735 421 www.microzed.com.au earthing needs to be incorporated into the mounting system. I have two motors doing different jobs. One turns at about 6 RPM and the other claims 17 RPM. Both have good torque. Brian Wilson, Curtin, ACT. LM317 regulator circuit has a potential trap A few years ago, while building an electronic device from a design in “Practical Electronics” magazine, I spotted a potential trap in the power supply circuit. This was a typical dual- rail circuit using LM317/337 regulators and in this case, used trimpots between the adjustment pins and the 0V rail to set the output voltages. It occurred to me that if a trimpot went open circuit (rare but it happens), this would put excessive voltage on the supply rail, killing some hard-to-get chips. My solution at the time was to put the trimpots between the supply rails and the common rail, with fixed resistors in the original trimpot locations. So when I read the letter from Peter van Schaik in Mailbag, (August 2008), I dug out my May 2008 issue of SILICON December 2008  7 Mailbag: continued Helping to put you in Control Control Devices New Mini DC Motor Speed Controller Control the speed of a DC motor rated up to 35V and 8A. Uses a microcontroller to accurately pulsewidth modulate a high current power MOSFET, IRFZ44. Features adjustable acceleration time, potentiometer, 05V or 4-20mA input signal control. Comes in easy mounting diecast box. Prices $69.00+GST. Ultrasonic Range Finder MaxSonar-LV-EZ0 is a low powered sonar range finder. Detects objects from 0.15 to 6.45 meters with 2.5 cm accuracy. Volts or Serial o/p $45.00+GST Flow Totaliser . Accepting a 4-20mA flow signal the KFMTA panel meter will display a 10 digit Total and 5 digit flow. Fully programmable using front keys $450+GST Photo-Contact Tachometer One instrument has both a photo and contact tachometer. Wide operating range 0.5 to 100,000RPM. Accuracy of 0.05% From $251+GST Serial LCD Module Control an LCD with serial commands. SerLCD supports 16 and 20 character wide screens with 2 or 4 lines of display. Adjustable baud rates. A variety of coloured LCD’s available. From $26.95+GST Temperature and Humidity Meter Easily measure the temperature and humidity using this handheld unit. Measuring range: 5-95% RH; -10 to 50°C $125+GST Contact Ocean Controls Ph: 03 9782 5882 www.oceancontrols.com.au 8  Silicon Chip History of the AD8307 I was very glad to see Jim Rowe’s RF Power Meter article in the October 2008 issue. My reason for writing relates to the Analog Devices AD8307 chip used. A little history of that device series may be of interest. About 20 years ago, I was working with a team of engineers developing medical ultrasound systems here in Sydney and we were using a TI TL441 log amp. Ultrasound signal levels tend to be of wide dynamic range and you need a log amp to help with improving dynamic range for visual display. The TL441 had been around for ages and used in military radar systems – again a wide-range signal application – and eventually the chip went fully hermetic and then custom sealed for military only applications and we simply couldn’t afford to buy them, nor get them in the quantities we needed. CHIP to look at the circuit in question. My reaction was “Why are people still making these circuits this way?” So tell us, why didn’t you put the jumpers and associated resistors where the 120-ohm resistor is? Or is there some aspect of the LM317 circuitry I’m unaware of that makes this a bad idea? On a different subject, I have been following the PIC and PICAXE articles in SILICON CHIP for many years but never got around to programming any of my own because I had no other use for a Windows-bound PC. With the arrival of the Intel-based Macintosh I intended to try running XT in Boot Camp purely to try PICs but I never got that far because a few weeks ago I discovered something called “Arduino”. This uses open-source software, with kits something like the Basic Stamp but using Atmel microcontrollers available at very reasonable prices. You can still roll your own if you want, as with PICs, and there is software to run them in OSX, Windows or even Linux. Since then I have ordered, We started developing our own log amp and enquired of Analog Devices as to their range. They had them but not fast enough for medical ultrasound which runs to 10MHz real time. We designed and built a very good prototype using the full wave detector cells with differential current amplifiers (in the block diagram of the AD8307) and more discussions with AD led to a collaborative effort with our very talented analog designer which eventuated in a medical-grade log-amp based on our work. The series you are now using is based on that original design, although I don’t know if anyone at AD would know the history. I’m still designing and still see Australian engineering as being equal to the best in the world even though our budgets are often a fraction of our competitors. And I’m still reading SILICON CHIP, so keep up the good work. Braham Bloom, Russell Lea, NSW. received and built a couple of highquality development board kits from the USA for less than $A60 the pair, including shipping. All I needed to do then was download and install the programming application (as with the PICs), plug my USB cable into the Arduino board, which came with a USB B socket and an FD232 SMD chip already on the PC board, and try some sample programs (called “sketches”) that came with the download. All was fine except in the case of one sketch but by reading through the program listing I realised I had made an error in the hardware – easily fixed, especially since I had deliberately ordered kits with through-hole boards. SMD seems to be the norm with commercial kits but all kinds of different set-ups are available. I have not seen Arduino mentioned in SILICON CHIP but for electronics enthusiasts such as me who use Windows only under duress, the answer is at hand. Just Google that unique Italian name. I haven’t seen any direct siliconchip.com.au comparisons with PIC or PICAXE but cost-wise Arduino leaves the Basic Stamp in the dust! Rod Liddle, Hackham West, SA. Comment: one of the problems with the LM317 is that for it to perform as stated, it must have a 120Ω resistor (minimum) between the ADJ and OUT terminals. If your scheme could be implemented while complying with this need and also not resulting in excess current in that ADJ resistor, there is probably no reason why it could not be done. You would also need to ensure that the trimpot power ratings were not exceeded. Thanks for your information about Arduino. Most TV programming is trivial I fully agree with the Publisher’s Letter in the September issue. However, it is not just HD television that is being wasted, it is television per se. If ever a technology was looking for a home, high-definition television is but we haven’t yet learnt how to get the best from the “low definition” television technology we already have. It is a resource that is being squandered as huge quantities of trivia struggle to fill 24-hour broadcasting. The obsession with ratings means that we get endless sport, cooking programs, unfunny sitcoms, unlikely crime series and shows designed to bring out our avarice. Technology and science are almost exclusively ignored. Is it because they are too hard, too expensive or are the stations just too lazy to try to make sense of the world that surrounds us with electronics, communications, space, biology and chemistry? Television is a natural for “showing how”. So why are there few programs that do just that? Where are the programs that could enhance our leisure time with interests extending from stamp collecting, model railway building, pottery, carpentry and metal work? How about explaining the workings of hybrid cars, nuclear power stations, etc? So let’s tear ourselves away from the pap. Which network will be the first to use television for what it can be so siliconchip.com.au good at? Then we might have a real reason for adopting high definition. Mike Smyth, Cherrybrook, NSW. Microwave oven project should not have been published From time to time I have read your editorials pontificating about allowing virtually untrained people to undertake electrical wiring tasks in their own homes. I have also read the indignant responses from such people who claim they are quite capable of carrying out these (supposed) menial tasks normally performed by (I assume perceived) “money hungry” electricians – and doing a better job as well! Then you go and publish, with a front page headline, that project about converting an old microwave into a “PC Board Cooker”. Did you look at the submitted pictures before you committed them to print? Oh, yes you did, because you put warnings in the captions about the “green/gold wire”. And you STILL went ahead and published the pics! The use of “earth” wire as anything but a wire at (or close to) ground potential is a complete anathema to those of us who build equipment professionally and are practitioners of the electrical or electronics trade. I notice further on in the article the wire used came from a disassembled “lead” and this obviously resulted in an excess of the green and yellow “earth” wire which Mr Rixon used instead of using the “correct” blue or brown wire. To have an excess and use it in this way is no excuse for committing the cardinal electrical “sin” of using the green and yellow wire as a live conductor! The mounting of the UV tubes, although “innovative” at first read, relies on rubber grommets to isolate them from the metal surrounds. These grommets are going to deteriorate quite rapidly under the effects of the UV radiation from the tubes and end up brittle and useless for their purpose. The holding of the artwork against the circuit board using just the weight of a piece of glass – the artwork should be in intimate contact with the circuit board to prevent the “umbra” or “shadow” effect delineating the edges FRONT PANELS & ENCLOSURES Customized front panels can be easily designed with our free software Front Panel Designer • Cost-effective prototypes and production runs • Wide range of materials or customization of provided material • Automatic price calculation • Fabrication in 1, 3 or 7 days Sample price: USD 43.78 plus S&H www.frontpanelexpress.com December 2008  9 Mailbag: continued Frost-free fridges are power hungry With respect to David Robson’s request (Mailbag, October 2008) for the schematic for the Whirlpool Refrigerator Model WR127S electronic controls, such a document is very hard to obtain. The details are considered secret by the manufacturer. But this begs the question, why use a refrigerator with a frost-free defrost system anyway? Such a refrigerator is inherently energy hungry; you use power to refrigerate and you use power again to defrost. The defrost element is a glassenclosed wirewound element drawing something like 125 watts. This is running when you think the refrigerator is supposed to be off or at least, when the compressor is not running. The compressor runs and then the defrost heater runs – a double whammy on power consumption. Also the electronics tend to be susceptible to power supply problems – we get a lot of service calls to fix electronic controls in refrigerators. I would not personally run such a refrigerator on a solar power/ inverter/generator system. For my two bob’s worth – don’t use frostfree refrigerators on solar /inverter/ of the tracks. Intimate contact needs pressure, much more pressure than the weight of a piece of glass can supply. The rotating of the artwork while exposing – the ideal light source for this type of exposure is a point source, to alleviate this “umbra” effect even more. To use distributed source tubes is a compromise which most of us live with but then to rotate the artwork while exposing just compounds this compromise even further. If you have to use tubes for your exposure, hold the artwork under pressure and hold it still – please don’t rotate it! The semi-transparent glass on the front of the microwave and the perforated grid are there to protect you from microwaves – not light in the ultraviolet spectrum. You do make 10  Silicon Chip generator systems and don’t use the manufacturer’s electronic control systems! Best to run is the “Moist Cold” type with a simple mechanical thermostat. Better again, is to modify the refrigeration system to install a “bypass” solenoid valve across the compressor from suction to discharge and set to close after, say, five seconds (you will need a refrigeration mechanic to do this). The normally-open solenoid valve allows the compressor to start with a surprisingly low starting current, allows time for the compressor to run up to speed and then, on closing, allows the compressor to come under load. The solenoid valve wiring (you will need a licensed electrician to do this) and associated timer is connected into the start relay circuit, so that any possible start scenario will include the time delay. Such a system will start a very large refrigerator on a small generator or inverter, with inrush currents reduced to the minimum for maximum refrigeration capacity. In short, the inherent high starting current of the refrigeration compressor is completely eliminated. Bill Spedding, Wellington, NSW. a point in the article about not looking (“staring”) at the tubes while in operation but you will notice that all commercial exposure boxes make sure that there is absolutely no light escape while the tubes are alight. Using the door interlock switch was a “nice touch” but doesn’t quite achieve the “no light escape” standard. There remains only one more question. Why publish such an article in the first place? Otherwise, congratulations on the quality of your presentation and on your longevity as the only surviving Australian magazine serving our electronics hobby industry. Keep up the good work but please be a little more selective with what you publish. You do have a responsibility to mould those young minds out there, who use your magazine as part of their education, into the correct and safe practice of (hopefully) their chosen pursuit. Jeff Thomas, Falls Creek, NSW. Comment: we take your point about wiring but we did highlight the problem in the article. In fact, we feel it is often more effective to highlight what is wrong rather than just not publish. Another example of this is our highlighting the hazard of a reader’s suggestion that 240VAC plugs and sockets be used for low-voltage DC, in the October 2008 issue (page 8). The rubber grommets are normally intended for the rigours of under-bonnet use so they should last for a very long time with occasional exposure to the low UV output of actinic tubes. The same comment applies to your fears about users being exposed to UV. The UV output is low and is normally filtered by two layers of glass in the oven door. It should not be a problem. If people are worried, merely placing a layer of paper over the door would fix it. Finally, we don’t accept your objection to using a turntable. All light boxes have distributed light sources – the turntable will even that out. And if better clamping is required, it will immediately be obvious from the sharpness of the exposure. The reason why we published the project is that it cleverly combines the microwave oven timer with a cabinet to safely house the tubes – a very cheap solution! Furthermore, it recycles electronic equipment which would otherwise be dumped. Congratulations on reaching 21 years Firstly, I would like to offer congratulations to SILICON CHIP magazine for turning 21 years old. I have been reading and enjoying SILICON CHIP magazine for most of those years. Technicians, engineers, electronics enthusiasts and ham radio operators alike are lucky to have such a quality publication to enjoy each month. I have a few questions. My first question is regarding the “Little Jim” AM transmitter as described in January 2006. Why didn’t any of the normal retailers (Jaycar, DSE or Altronics) make “Little Jim” into a kit? siliconchip.com.au I waited about six months until it became obvious that there wasn’t going to be a kit and ordered the PC board from RCS Radio and the parts from Jaycar and built it that way. The transmitter worked as described and I was suitably impressed but I was still left confused as to why it wasn’t released as a kit. I received my training as a TV repairman on CRT TVs. Now the TV repair landscape has changed. I assume “The Serviceman” was also trained in the days of CRT TVs. How did he learn how to repair LCD and plasma TVs? Is there a book available? Has there ever been a SILICON CHIP article for an “on-air” sign for ham radio operators? If not could you develop one? The circuit would be based on a 555 timer and a Mosfet in the output. This sign would be fixed outside the radio room and would flash when turned on, thus indicating that you are on the radio. My suggested “on-air” sign would be made out of red LEDs and would be about 25cm wide by 10cm high. The only added expense that I can see is the home-made box to house the sign. Ross Fraser, Narromine, NSW. Comments: most TV serviceman would have done what is called “on the job training”. However, some large companies do have quite good training courses as each new family of products is released. We don’t know of any suitable books on the subject of servicing plasma and LCD TVs. The decision whether to make each of our projects available as a kit is up to the retailers. We would love them to have every project available as a kit but that would be utopia. We have not done an on-air light project but if you want a suitable circuit, have a look at the 12V Speed Control project which was published siliconchip.com.au Don’t take short cuts on batteries I wish to comment on Stan Swan’s well-intentioned but dangerous statement on page 21 of the article on 10W solar panels (November 2008). He states: “The 10W CIS panel and regulator looks capable of being linked further to a larger capacity battery . . . as further SLAs (or even a car battery) could be paralleled for greater energy storage”. It is just this kind of abuse of installation procedures that leads to solar getting a bad name for ineffective delivery of power and worse still, creating the scenario where wiring is burnt out, fires started and even batteries exploding. One of the major problems I faced when installing solar systems was to get people to recognise the need to correctly size a battery bank. When batteries (or cells) are new, they have reasonably consistent internal impedance. Over time, with repeated cycling, plate gaps alter and cell impedance changes. The bulk of charging current will go to the paralleled battery with the lowest impedance, resulting in that battery losing more water by hydrolysis. Actual capacin the November 2008 issue. It is based on a 555 timer and a Mosfet and you would just need to reduce the operating frequency to a very low value to get it to flash the sign. Electric braking for a caravan Regarding N. W.’s desire for an indicator of the amount of braking effort being applied through his Brake Controller (Ask SILICON CHIP, November 2008), a simple 12V Bezel Lamp connected to the blue lead from the ity is not increased as much as one would be lead to believe. The other major problem may be inconvenient when using low capacity batteries but when ampere-hour capacities are in the hundreds or thousands, the energy stored is capable of producing horrifying results. Should one cell in a paralleled battery internally short or suddenly get a very low internal impedance, the current flow from the other battery discharging through the faulty cell can reach hundreds of amps, either burning out wiring or heating the faulty cell to explosion point. Good practice in solar installations is to correctly size the battery to maximum planned expansion at the time of installation, then increase generation sources and utilisation later. Never compromise on batteries, thinking that a defunct battery from a car will be OK. It cannot be anything else but defunct in a solar installation too. More could be said about the need to use deep-cycle versus high CCA type batteries, loss of efficiency as batteries age, etc but I think the message is clear. Don Pearce, Gledhow, WA. controller and earth will provide all the indication he needs. The lamp needs to be a filament type to integrate the PWM power signal supplied and the brightness is roughly proportional to braking effort. Anything over 75% braking effort will mean that he is too busy to look at an ammeter or other display! Position the lamp well down on the dashboard where it is not a distraction in everyday driving. Brian Wilson, SC Curtin, ACT. December 2008  11 An “electric” concept car due here in 2012: the Chevrolet T he Sydney International Motor Show has come and gone, under a blaze of spotlights and almost continual buffing fingerprints off paintwork and glass. Of course, the Ferraris and Lamborghinis earned lots of “oohs” and “aahs” from the admiring crowds (and probably thoughts of “when I win Lotto . . .”). But it was the more everyday, perhaps even prosaic vehicles which attracted the most attention. Maybe it was the economic climate There was plenty for the rev-heads but this year the theme seemed to be a definite shade of light about 550nm in wavelength (OK, green for the uninitiated). 12  Silicon Chip Many manufacturers featured small, efficient diesels (remember not too long ago when “Diesel” was a dirty word?). Hybrids also seemed to be the order of the day, with several manufacturers offering their particular variants. The Toyota stand had them stacked up the wall and sitting at 45°angles, as well as rotating in front of you. Toyota’s Hybrid Synergy Drive (Oh What a Feeling!) was everywhere, even in the flashing LED and LCD signs (printed signs, such as featured on the Ford display next door, are so passé). But there was little to differentiate the new Camry’s propulsion system from the new Prius propulsion system. It’s a hybrid. Honda had their Insight, which was no different to last year’s Honda Insight (or the year before’s, if you believed the salesman). “But there’s a new one coming soon,” he said. How soon? “Ummm – next year?” Even Lexus had their up-market hybrids alongside their new LF-Xh concept car (which has a V6 engine plus an electric motor driving all four wheels). While Toyota’s Prius has claimed the prized top-of-mind position when it comes to hybrids, Lexus has sold more than 2000 of their up-market hybrids in the past two-and-a-bit years. siliconchip.com.au Star of the Sydney International Motor Show? Volt Mazda had their striking “Taiki” concept car on display with its completely-enclosed rear wheels. Like most concept cars, this one is very unlikely to see the light of a showroom but Mazda (like all concept car producers) maintain that many of the design elements in the Taiki will emerge in the next generation of street models. When saving energy is right at the top of a designer’s wish list, the Taiki’s 0.25 drag coefficient cannot be ignored. But then again, neither can its shape. Nissan again featured their Mixim electric vehicle but this was not particularly newsworthy – it’s been seen before. siliconchip.com.au Something that has not been seen before (at least in Australia) was taking pride of place on the GM-H stand: the Holden (or perhaps I should say Chevy) Volt. Will it be a Holden when it eventually reaches our shores? Now here was something different, something worth a lot closer look. The Chevy Volt This is a vehicle based on a whole new design philosophy, one that has attracted a lot of comment in the media and on the web. It is an EREV – an Extended Range Electric Vehicle – which marries several different genres. by Ross Tester First and foremost, the Volt is a true electric vehicle – the wheels are driven solely by an electric motor, powered by a bank of on-board batteries which are in turn charged overnight from the mains supply. But it also contains a small, efficient, internal combustion engine (ICE), so does that make it a hybrid? No, because in a hybrid the ICE can also power the wheels. In the Volt, it cannot: the ICE is solely responsible for charging the battery when it reaches its limit of about 60km. The ICE is where the EREV part comes in – the motor extends the range up to 400km. December 2008  13 The small tank on the left is the fuel tank for the on-board generator. It sits on top of the rail containing the top of the battery bank. You’ve probably picked up on that 60km basic electric range. GM’s research suggests that 75% of commuters (at least in the US) travel less than 40 miles (64km ) each day, so they designed what amounts to a “town car” to precisely target this market. In this use, most of the time the ICE will never cut in but it takes away the so-called “range anxiety” which drivers of electric-only cars face: “what do I do when the battery runs out and I Engine Generator Electric Drive Unit am stranded miles away from home/a power outlet/etc?”. Another concept car In truth, the Volt is also a concept car – a car that never was, nor will ever (probably) be. The plan is to release a Chevrolet Volt in the USA in late (November) 2010 and then in Australia sometime in 2012 but the odds are a million-to-one on that it won’t be this exact vehicle. For a start, according to GM’s own press releases, they have yet to determine which battery manufacturer will get the nod. At the moment there are three manufacturers vying for what will be a very lucrative contract. But more on the battery shortly. There’s also the engine: some reports suggest that the engine in the display model Chevy Volt is no more than an electric golf cart motor capable of moving it around “a bit”. In conjunction with some major players and many minor ones, GM are still developing much of the “important” bits – like motors and batteries! However, GM have said that the Volt chassis, look and running gear is probably very close to what will appear on US (and then world) roads. The engine We cannot tell you much about the electric engine because the final design hasn’t been chosen yet. However, GM are looking toward a motor with the equivalent of 150hp/110kW, 370Nm of instant torque (you gotta love electric acceleration!) and a top speed of – wait for it – 160km/h. This seems to be a bit of an enigma: if you’re designing a town car with limited range for commuters, why give it freeway top speeds? Because they can? Lithium-Ion Battery Charge Port Here’s a chassis-only view of the Chevy Volt. Note the T-shaped battery (shown here in blue). Our first reaction when seeing this diagram was “why not add more batteries for longer range?” 14  Silicon Chip siliconchip.com.au A couple of snaps of the display model Volt at the Motor Show. Above, a cutaway showing part of the battery pack (ignore the black thing above it – that’s a large Plasma screen to extoll the Volt’s virtues!). At right is what will be the motor and control units (at the moment, the motor is from a golf cart!). However, if other electric cars are any yardstick, with a top speed of 160km/h, idling along in city traffic should dramatically increase range but GM have made no comment on this. The ICE generator is highly efficient, having just one task – turn a generator. Therefore its power band and operating parameters can be maximised, unlike a normal petrol (or even diesel) engine which must be able to power a vehicle from rest to top speed under various loads and therefore is a compromise. The motor appears to have already been chosen, with a model capable of running on either straight petrol or anything up to 85% ethanol blend. The fuel tank in the concept vehicle is tiny, appearing to be not much more than about 25 litres in capacity. The battery and charging Obviously, the battery is the most important part of any electric (or even hybrid) vehicle. In the Volt, we know that (at least currently) the battery will be a T-shaped, 16kWh Lithium-Ion type, consisting of more than 220 cells. GM are very close-lipped about the actual make-up of the battery but reports we have seen suggest that they are working on a design with a 3-phase 320V AC motor, so that gives some indication of battery voltage. The batteries run along the centreline of the body and out towards the back wheels. The batteries are not allowed to discharge below 30% – that’s when the ICE generator cuts in, or you start to charge it from the AC mains via its on-board, intelligent charger. GM claim that it will be possible to charge the battery in less than three siliconchip.com.au hours “from a standard 110 or 230V household outlet”. That’s a rather hefty charging current – about 16A or so by our calculation (16kWh x 70% /3 hours = 3.73kW per hour; 3730/230 = 16.2A). Add in the inefficiencies in both the charger and the actual charging (say 85% each) and that adds up to more than 22A. We’re thinking that the vast majority of users will want to charge the Volt from cheaper off-peak power (or whatever it’s called in a few years) so they will need to have a special outlet installed anyway. And yes, we’ve checked: you are allowed to use off-peak power to charge a battery, even one in an electric vehicle! Cost to charge At current Sydney off-peak rates (5.83c/kwh) it’s going to cost the best part of a dollar to charge the Volt (16kWh x 5.83c). Worst-case scenario (with PowerSmart Peak <at> 30.25c/kWh) that would jump to around $4.80. Remember, this gives you about 60km of “all electric” driving. GM’s costing is around $2.00 for a night-time charge and on their figures, that 75% “average 60km commute” would result in cost savings of about $4400 annually (Australian dollars). Obviously, without tests, this figure can neither be confirmed nor denied and just as obviously, doesn’t take into account any battery replacement costs. Otherwise, you would expect operating costs of the Volt to be lower than a conventional petrol-powered car as service costs should be lower for a petrol engine that works only a small percentage of the time. Incidentally, GM claim that the Volt will cost around 4c per kilometre to run electrically versus about 24c/ km for an equivalent-sized petrolpowered vehicle. The vehicle The Volt is a front-wheel drive, fourpassenger model that from the outside, simply looks like a modern car. However, significant attention has been made to getting the body shape just right to achieve the lowest coefficient of drag – wind resistance – thus maximising range. This is a feature of most modern passenger car design, certainly not limited to the Volt. It also uses specially-developed, lowprofile, low-rolling resistance tyres on 17-inch rims, again to minimise drag and therefore range. Many of the design cues from the concept vehicle will endure in the production Volt, including the closed front grille, athletic stance, rear design graphics, outside rearview mirrors and more. The Volt’s rounded and flush front fascia, tapered corners and grille are functional, enabling air to move easily around the car. At the rear, sharp edges and a carefully designed spoiler allow the air to flow off and away quickly. An aggressive rake on the windshield and rear screen help reduce turbulence and drag. Inside, the Volt will offer the space, comfort, convenience and safety features that customers expect in a fourpassenger sedan and it will deliver them in a variety of interior color, lighting and trim options unlike any offered before on a Chevrolet sedan. Modern controls and attractive materials, two informational displays and a touch-sensitive “infotainment” centre with integrated shifter will distinguish the Volt’s interior from other vehicles on the market. Some of Volt’s interior technological December 2008  15 Preliminary Specifications General Vehicle Type: Category: E-REV Competitors: Chassis: Seating Capacity: Performance Top Speed: EV Range, City (km): 5-door, front-wheel-drive sedan. Extended-Range Electric Vehicle (E-REV). None. Independent MacPherson struts front, compound crank twist axle rear, four-wheel disc brakes, full regenerative brakes to maximise energy capture, electric power-assist steering. Four. 160km/h 64km Dimensions Wheelbase: Length: Width: Height: Cargo Volume: 2685mm 4404mm 1798mm 1430mm 301L Battery System Type: Energy (kWh): Lithium-ion. 16 Electric Drive Unit Power (kW / hp): Torque (Nm / lb-ft ): 111 / 150 370 / 273 Exterior Tyre and Wheel Size: Specially developed low rolling-resistance tyres on 17-inch aluminium wheels. features will include: • Driver-configurable, liquid crystal instrument display. • Standard seven-inch touch screen vehicle information display. • Touch screen-style climate and “infotainment” controls. • Optional navigation system with onboard hard drive for maps and music storage • Standard Bluetooth for cellular phone and USB/Bluetooth for music streaming Driving the Volt will take some getting used to – there will be virtually no noise from the electric motor and even when the ICE generator fires up, its noise level will be way below conventional vehicles. Acceleration may also catch some drivers by surprise! Green power? A lot of argument about the “greenness” of the Chevy Volt has centred on its power source. The argument goes that by taking power from the grid to charge an electric car, one is simply transferring pollution from the exhaust pipe of the car to the exhaust stack of the power station. GM is quick to point out that a lot 16  Silicon Chip of electricity generation in the USA (27% by some reports) is from noncoal-fired sources and even then, modern coal-fired power stations are much better in the pollution department than previously. By taking large numbers of petrolpowered vehicles off the road and making them electric, they maintain there will be more incentive to make electric power generation cleaner and the atmosphere will also be cleaner from less vehicle pollution. A good argument? Only time will tell! Translate that to Australian dollars (which may be up, down or sideways by 2012) and you are paying a very high premium for an electric vehicle. If it was me, I’d be with many of the web commenters: “I’d love one, but SC not at that price. . .” How much? The Chevy Volt initially had a target price of $US30,000. By GM’s own admission, even now (two years before its release) that price has blown out to $US48,000 (almost $AU70,000 at time of writing but who knows!). Whether this cuts out a significant portion of the market for GM is already causing a lot of discussion on the web, with many people raising serious concerns about the price increase (and remember, like-for-like US new car prices are on the whole significantly cheaper than ours). Oh, what a feeling: Toyota’s stand had their Camry hybrids stacked like Matchbox toys! siliconchip.com.au BOOK REVIEW By Leo Simpson TV Across Australia – One For The Grey Nomads TV Across Australia, 4th edition, published 2007 by Vision Logistics, Hume ACT. 191 pages, 212 x 297, paperback. ISBN 978 0 9775798 2 2 $49.95. W E OFTEN RECEIVE requests from people wanting to know the details of TV transmitters: channel number, polarisation, location of transmitter and so on. This is vital information if you are setting up a new antenna but it is even more important if you are one of the growing band of “grey nomads” out touring Australia. Each time they come to a stop they into AUDIO? There’s something to suit every audio afficionado in the SILICON CHIP reference bookshop Self on Audio – 2nd Edition by Douglas Self A collection of 35 classic magazine articles from the world-renowned audio guru. So good we use it as a reference here at SILICON $ 83 CHIP! A must to own. Audio Power Amp Design Handbook – 4th Ed. by Douglas Self Huge 465 page manual covering just about everything in audio power amplifiers $ 87 Audio Electronics – by John Linsley Hood Covers everything in audio from tape recorders, tuners, receivers, preamps, voltage amps, power amps and much more. $ 101 You’ll find many more technical titles in the SILICON CHIP reference bookshop – on pages 92 & 93 of this issue siliconchip.com.au need the details of the local TV transmitter so they can point their antenna in the right direction. This information is available for every radio and TV transmitter in the country on the ACMA website. However that site is labyrinthine and the transmitter info is difficult to find. The link is http://www.acma.gov.au/WEB/ STANDARD/pc=PC_9150 There you will find a series of pdf files available for download, including three for TV stations. The most useful one that lists transmitters by locality is: http://www.acma.gov.au/webwr/_assets/main/lib100059/tv_8.pdf However, it runs to 132 pages and it would not be much use to someone in a remote caravan park somewhere in woop woop, especially if they did not have a laptop computer and an internet connection. That is why this book is a much more convenient solution. It is divided into four sections, the first of which is the location guide. It lists more than 1000 transmitter locations throughout Australia and in each case there is a reference to one of the 28 maps in section 2. The maps are very useful because not only do they show the transmitter location you are looking for in particular, you can also see others in that location. So say you are in the Kalgoorlie area in Western Australia. Map 20 will show that there is a transmitter at Kalgoorlie as well as others relatively close by at Coolgardie, Kambalda, Broads Dam and Ora Banda. In a pinch, one of those other locations might give you useful reception. Having identified the potential transmitter locations, you can refer to the alphabetical listing which gives the details for each transmitter, over 4000 of them: town or area, network (eg, SBS, ABC etc), channel number etc. In each case, you can see whether the transmitter is digital or analog, the VHF or UHF band, the polarity (Vert­ical or Horizontal), transmitter power, transmitting pattern (omnidirectional or directional) and the latitude and longitude. The transmitting pattern is most important because if it is directional, most of the transmitter power will be aimed at the main population areas. This can be a problem if you are not in those areas. You will also need to know if the transmission is digital or analog and we would assume that anyone touring Australia would also have a set-top box, if they don’t have a digital TV set onboard. If you are about to install an antenna, there is also a suggested Clipsal antenna for every location. By the way, the publication is sponsored by Clipsal. Finally, the fourth section is a comprehensive appendix of information about antennas, radio frequencies, signal propagation etc. There is also a catalog of Clipsal antennas, antenna installation methods, splitters and modulators. Also listed is a range of equipment by Kingray. All in all, for anyone interested in doing an antenna installation or planning an extended tour around Australia, this is a most useful book. It is available from the SILICON CHIP bookshop at $49.95 plus $7 packing SC and postage. (L.D.S) December 2008  17 DIGITAL CINEMA There is upheaval in the movie industry. More feature films are being shot with digital cameras and successfully transferred to 35mm film release prints with advanced technology. Surprisingly, film is still hanging in as a capture medium, due mainly to the pressure from cinematographers who claim that everyone wants that ‘film look’, while few set out to achieve that ‘video look’ in the cinema. Coming up fast on the inside is the ‘digital look’, as increasing numbers of cinemas around the world begin to install digital projection into their bio-boxes. Barrie Smith takes a look into the popcorn and choc-top world of the digital cinema revolution. 18  Silicon Chip siliconchip.com.au D epending on who you ask, the cinema industry, as distinct from the production side, is under challenge – from metre-plus LCD and Plasma 16:9 home screens — or it’s not under challenge, thanks to a flood of successful block-busters. These are pulling millions of dollars from patrons happy to travel to a multiplex, sit in the dark with a crowd and enjoy the movie experience after paying $16 plus for each ticket. The Australian figures are revealing: In its 10 week run Batman’s Dark Knight pulled $45 million while Mamma Mia! did $30 million in a similar period. Movies make money. Buckets of it. The two thousand cinemas that constitute the Australian exhibition industry all have film projectors, mostly 35mm models that have served operators well for decades. The principle of 35mm projection has remained basically unchanged since 1895, when the brothers Lumiere held their first public movie screening, at Paris’s Salon Indien du Grand Café. Wise minds would say “Don’t mess with it. It works.” That makes you wonder why there is a push to digital cinema. To find out, why I spoke to some industry players busy trundling digital projection gear into cinemas across the nation. Savings A man who could easily be described as the head of the push (to digital cinema) is Kodak’s Asia Pacific Digital Cinema manager David Sanderson. I asked him why we needed digital cinema. Sanderson responded by saying it could be compared to most new technologies in that it “offers potentially big savings in certain parts of the industry.” He tempered that by saying that in other parts “it probably doesn’t offer savings but the main drivers who are probably the studios and distributors out of the US would love to see it happen.” He sees that there is definite pressure to get the US market converted quickly but adds there is less pressure in other parts of the world. Europe, he feels, is probably a secondary area and probably the furthest away in US minds as far as conversion goes. As of now it is estimated that 1200 cinemas, or about 1% of cinemas siliconchip.com.au 35mm film projection has remained basically unchanged since 1895. As anyone who has been to a cinema knows, a lot can (and does) go wrong! worldwide, are equipped with digital projectors. Australia is also well back in the field with possibly 24 or 25 cinemas equipped with 2K standard digital projectors (see Info Box), virtually all in capital cities. For example, The Greater Union chain is currently trialling digital projection in some of its major cinemas, including the “Gold Class” cinemas where there’s the added attraction of dinner and drinks served to your seat (such as shown in our photo opposite). The situation here is that most film projectors that are still running side- by-side with digital are dedicated to 3D projection when it is scheduled. That situation would change dramatically when a serious roll-out of digital happened, Sanderson stressed. What are the benefits for the audience? The Kodak man explained that the benefits are very straightforward for an audience. For a start, you avoid today’s issues that we have today with film prints, where the film prints get scratched and dirty as they get cycled around the country. With digital it’s very different. First of all, you get projection of a pristine image from day one to the last day. The Barco DP3000 projector using a 3 cm DLP chip is a 4K machine with 6.5 kW lamps and ability to cover a 30mwide screen. AIST is currently testing this model and Barco’s DP2000 at the Greater Union George Street Sydney cinemas. December 2008  19 Atlab Image and Sound Technology are pushing ahead with their own approach to digital cinema and see little demand for 4K projection. other benefit for the audience is going to be that more cinemas will be able to show a new movie on day one, thanks to the lower cost per title. Country cinemas can then enjoy simultaneous release with the capitals. And for the cinema operator? Automation is the key to the cinema’s main benefits. When a cinema multiplex is fully digitised, a Theatre Management System (TMS) is installed — virtually, a computer that runs the show. The movie on a hard drive is loaded into a server and then the TMS works with the ticketing system that the cinemas use today to program what shows run on what screens. At that point, the TMS takes over and sends the movie data to the appropriate projector/screen and starts the movie at the right time. In fact, it runs the whole show — dims the lights, opens the curtains etc. The Key The movie can be delivered in any of three different methods to cinemas: via remote management on a Virtual Private Network (VPN), by satellite transmission or by physical media (a hard disk drive). Also sent to the cinemas is the Key Delivery Message (KDM), most likely in the form of a USB flash drive or sent via a phone line and a modem. This is provided by a film’s distributor or its laboratory. The KDM is the more than an antipiracy device. It’s the content key that unlocks the encryption on the movie and therefore unlocks the movies for the correct dates on which the cinema is allowed to play it and what day it has to finish. If a theatre wants to screen a movie outside of the parameters the KDM allows, they would need to obtain a new KDM from the distributor. There’s even more to this locking process, as explained in the Info Box ‘Anti Piracy’. Out of Focus Today’s metro multiplexes are operated by minimal staff. You’ve probably found that the standard of film projection at your local multiplex confirms this, with delayed projection, the movie often out of focus or out of rack for five minutes or more, with sound frequently at painful levels until the projectionist corrects matters. Digital projection can only improve this situation and allow a multiplex with ten or more screens to be operated A portable hard drive, costing less than $100, compares to around $2000 for a 35mm movie film print. And the film print is easily damaged and is very heavy (some theatres have a fork lift to raise the spool to the projector!). 20  Silicon Chip siliconchip.com.au Main Players Christie CP2000-ZX (Above): A line-up of Christie DLP projectors with the lens inset at left. correctly with just a few operators. A handful of projectionists could move between screens and keep an eye on where things are from one screen to another. But, Sanderson stresses, “you know you need to have someone there in case something does happen, and that will still apply with digital.” Digital also means the whole show — say a movie plus ads plus trailers for coming movies, can all be run as a single program. Sanderson: “It’s all moving in that direction very quickly. At the moment you’ll tend to get the ads possibly run from a separate digital system to the main movie and the trailers could be today running on 35 mm film. Christie projector lens and LCD panel setup … the latter is used to create projected 3D. siliconchip.com.au There are five main suppliers of digital projectors to the cinema industry: Barco, Christie, NEC, Panasonic and Sony. Four of these, Barco, Christie, NEC and Panasonic, use the Texas Instruments DLP cinema chip, which is in essence the world’s most sophisticated light switch, using a rectangular array of up to two million hinge-mounted microscopic mirrors; each of these micromirrors measures less than one-fifth the width of a human hair. A DLP chip’s micromirrors are mounted on tiny hinges that enable them to tilt either toward the light source (ON) or away from it (OFF), creating a light or dark pixel on the screen. The white light generated by the projector’s lamp projection system passes through a colour wheel as it travels to the surface of the DLP chip. The colour wheel filters the light into red, green, and blue, from which a single-chip system can create at least 35 trillion colours in a 3-chip system. Sony, in its CineAlta SRX R220 projector uses a Silicon X-tal Reflective Display (SXRD) imaging device based on a variant of LCD technology. Sony CineAlta SRX R220 December 2008  21 If a cinema wants to run 3D movies then it may need to install a high gain screen for some processes. Some cinemas currently run 3D movies with an on screen illumination of only 8 foot-lamberts One process, the RealD 3D system needs a metallised screen because it’s a polarised light system. There is also a Dolby 3D system which needs a high gain white screen, because of the filtering system used in the process. See Info Box ‘Three Dee’. VPF Christie DLP projector and associated server. “In the future it will all run through the one digital projector.” Is there a difference? I asked Sanderson would an audience know the difference with digital. He answered that generally the audience doesn’t, unless they are attuned to looking for scratches or dirt on the print. He added that the quality of film and digital are very similar. So, in fact if the audience doesn’t notice the difference, it’s a success. With a new digital installation it may not be necessary to upgrade the audio set up. If the cinema already has a high quality system the existing set up will work well. Unless the cinema plans to run 3D movies there is no need to change the screen itself. The standard screen illumination is 14 to 16 foot-lamberts and digital installs are designed to run at this level How will the cinema operators pay for digital? Sanderson: “At the moment, if they are running 3D, they’re having to do it out of their own pockets. This is countered by a premium price for 3D admission tickets.” Then there is the Virtual Print Fee (VPF) scheme requiring co-operation from the US film studios and a company like Kodak, who can support a roll out of digital cinema. Once agreements are struck with a finance company then you can start to roll digital installs. A VPF pays off the equipment and does not go to the cinema. The cinema basically has to put up a small portion of the total cost to join in the scheme and as soon as they sign up then the equipment goes into their cinema and from day one they just show movies in digital. Roll-outs The matter of cost per installation opens up another can of worms. According to Sanderson this figure can probably reach $100,000 “by the time you get the equipment and the screen and everything set up. “For every screen you have to have a projector. Then you’ve got to have what’s called a content player, a computer box that actually stores the movie on it that’s going to play to that screen. “And then you need automation interfaces — the devices that turn lights on and off, open the curtains and all that sort of thing. Added to this and constituting the master control is the TMS. You need one of these for the multiplex; it talks to each of the individual content players and projectors in each of the cinema halls.” 22  Silicon Chip Operator using Barco DP100 projector. Relying on DLP chip it delivers 2K projection and can illuminate a 25m-wide screen and use Xenon lamps from 1.5k to 7k in output. siliconchip.com.au VPF is similar to a surcharge on the rental cost per movie, with the distributor or the US studio financing the roll-out. This would be a massive saving when the latter can distribute digital files to the cinemas when compared to the cost of distributing rolls of film today. This is happening in the US and Europe at the moment but has been stalled for the last 12 months, mainly because of the lack of finance. Release Will digital cinema help the smaller film producer with a title on limited release? Sanderson: “I think the answer is yes, because they can go through the post production phase which is probably lower in cost in digital, particularly if they want to get it out to a lot of cinemas, then making digital copies is a lower cost. A block-buster, such as a Batman or Bond movie, can face a simultaneous release to possibly 2000 or so screens Australia-wide. With a 35mm print cost likely to be around $2000 per copy, you don’t need a PhD in maths to see that a digital release of a movie on portable hard drives at less than $100 a pop would have the movie people salivating at the thought. The only counter to this is that, for a while to come, film distributors will need to have dual inventories of film and digital release media. In the long term though (probably within five to ten years), the benefits would be substantial. Satellite distribution would seem to ignite another fire in the movie industry’s eyes and remove all media costs. David Sanderson feels this is some way ahead and, to illustrate the situation, recalls talking to a very large company in India, who own a fibre optic network that encircles the country. He explains that, while the Indian company can distribute the movies via that system it still takes them something like twelve hours to push a movie out through the network. A two hour movie, even in compressed form, can reach 250GB. Opportunities Digital presentation also delivers many opportunities to the canny cinema operator in the form of television presentations. Both globally and in Australia, live presentations of sport and opera are already in train. The only attraction that film may still maintain is the culture of film. “Talk to any major cinematographer and you will hear they still want to shoot with film because of the creative benefits it affords them (real or perceived).” Although video camera technology is striding ahead, particularly in 2K or 4K? Digital High Definition TV has a vertical resolution of 1080 pixels, with a horizontal resolution of 1920 pixels. It’s generally understood that no detail whose width is tinier than 1/1920 the screen’s width — a single pixel — can be seen. Digital movies are created by digitally scanning the original 35mm film and packaging the data into a DCP (Digital Cinema Package) for distribution. Most commonly, the digital movie is distributed on a portable hard drive. 

There is compatibility between current 2K and 4K systems. Movie files created at 2K can be exhibited on 4K systems — 2K images are automatically up-converted to 4K data; a 2K projector can replay a 4K movie but limited to 2K quality onscreen. The interchangeability between 2K and 4K means that studios need only distribute one movie file, whether it is 2K or 4K, and it can be played by any compliant projection system. In a 2K scan from film to digital, the number of pixels across the width of the scanned film frame is, at most, 2048 pixels. In a 4K scan, that upper limit is doubled, to 4096 pixels. What is the difference between 4K and 2K projection? In digital cinema, a 4K image with a 2.39:1 (“scope”) aspect ratio has 4096x1716 pixels. A 4K image with a 1.85:1 aspect ratio has 3996x2160 pixels. By comparison, a 2K image with a 2.39:1 aspect ratio has 2048x858 pixels. A 2K image with a 1.85:1 (“flat”) aspect ratio has 1998x1080 pixels. Kodak’s David Sanderson made the point that future movie resolution might be 8k on the screen — and not 2K or 4k — but the audience would not see any difference at all. 4K Digital Cinema 2K Digital Cinema 1080 High Definition 720 High Def SD TV RealD 3-D system uses a single projector that alternately projects the right eye and left eye frames and circularly polarises these frames, using an LCD screen in front of the projector lens. siliconchip.com.au This diagram, courtesy of Red Digital Cinema Cameras, shows the relativity between a standard definition TV (grey), a 720pixel high definition screen, a 1080 pixel high definition screen, 2K cinema screen and 4K cinema screen. December 2008  23 Three Dee The RealD 3-D system is based on the traditional method of 3D imaging, using linearly polarised glasses. The traditional method works by projecting two linearly polarised images onto the same screen, polarised at +45° and -45° from the horizontal, which are then filtered by linearly polarised glasses worn by the audience. This type of 3D imaging requires two projectors, and often suffers from visible double-imaging if the head is tilted to the side, thereby cancelling the polarised effect. RealD however uses a single projector that alternately projects the right eye and left eye frames, and circularly polarises these frames, clockwise for the right-eye and counter-clockwise for the left eye, using an LCD screen in front of the projector lens. Circularly polarised glasses make sure each eye sees only its own picture, even if the head is tilted. A high frame rate of 72 fps per eye is used — each frame projected three times to reduce flicker, as the source vision is usually 24 fps. Some of the films in RealD: Chicken Little (2005), Monster House and Beowulf (2007). Globally, 1000 screens ran the latter title in 3D. Dolby 3D is based on INFITEC (Interference Filter Technology) technology, originating from a research project of DaimlerChrysler. INFITEC uses an extremely fine-tuned colour/filter wheel. Light waves entering the eye are separated into three different spectral ranges by three types of receptors, related to the primary colours. Dolby 3D uses six very narrow bandwidth colour bands — three for each eye. This allows the use of one light source in a single-lens projector. There are processes in the works to 3D-ise moves that were not originally shot in 3D. Dominic Case has the wry comment that while “there are some very clever people who are purporting to take an old 2D image and 3D-ise it, I’m waiting to see Casablanca in 3D — and slit my wrists when that happens!” 24  Silicon Chip the form of the RED camera, it does not change the technique of making movies: the cinematography, the lighting, production design etc. It’s the technique and the culture, not the technology. As David Sanderson stresses “It’s about the creative requirements of the guys that produce the movies and the creative people who have very, very high ideals of what they want. It’s not just a matter of saying here is the new thing, let’s go with it. To change the way you actually make a movie is a very different set of criteria.” Another matter is that Kodak does make the odd roll of motion picture negative and print film, sold to film companies and laboratories by the millions of metres. Film will be around for a while, even if Kodak pushes the digital barrow as strongly as they intend. Another Approach To get a totally different view of the technology I spoke to Dominic Case, Communications Director of Atlab Image & Sound Technology (AIST) in Sydney, a major player in the Australian industry who previously, as Atlab, had been the country’s major processor of motion picture negative and prints. AIST’s digital cinema ‘product’ is ‘ec2’. This approach arose because the company viewed the approach by the Hollywood majors as one based on a financial model that did not make sense, at least in the Australian environment. The company began with ec2 some years ago as a method that provided quite low end digital projectors for cinemas to run pre-show advertising in the form of TV commercials transferred to film, or as slides and PowerPoint-like presentations. Case: “We started out doing that and supplying the equipment through our cinema equipment division called Atlab Image and Sound Technology (AIST). We have now upgraded that to a level where the image quality is suitable for showing features in all but the largest of cinemas. It’s a slightly lower resolution than the 2K that Hollywood demands — it’s 1.3 or 1.4K — and we manufacture our own server that handles the files for that. This rolls out to the cinema operator for little more than $20,000.” Case claims that, for a suburban multi-screen cinema with a smaller screen, the quality is close to that previously experienced with film projection. He adds that there a “couple of hundred cinemas” are currently showing presentations in a process that has come to be called eCinema. “The point about eCinema is that the Hollywood studios won’t allow their product to be shown in it but independent distributors can tap into live screen presentations of ballet and opera, organised by the Australian Film Commission and screened live in a handful of rural cinemas.” It also means that the independently-owned smaller chains as well as regional cinemas can now get art house and Australian-made films, supplied on portable hard drives that they couldn’t get before because there weren’t enough prints available. In a typical ec2 install the cinema is supplied with a server and a digital projector. AIST fits its own logic boards and operational software to supply the Panasonic LCD projectors. At this pricing level it also means a private home could install cinemaquality theatre to run top movies. The only flaw in this idea is that a private individual would probably not obtain access to first-run films. Case sees the whole approach as an exercise in diminishing returns and it means you can get 90% of the on screen quality for a quarter of the price. In practical terms, Case is a realist and believes that watching audiences probably cannot differentiate between film and digital projection … “essentially most audiences we find haven’t a clue of what they are watching, qualitywise. Very few people can actually say digital is better or worse.” More likely is a negative response when “some cowboy shows a DVD on a data projector and calls it digital cinema. We hear of a few of those and people come out of that saying: ‘If this is digital cinema, I don’t want to go again.’” The cinema operators see it quite differently, Case explains that one of the attractions is that they can rent movies (in digital form) that they wouldn’t get otherwise: “They can enjoy quite flexible programming. They’re not changing from film to digital. They’re putting a digital projector in alongside a film projector.” “This means they can still be showsiliconchip.com.au ing their mainstream films, their blockbusters in the evenings of high attendance days like Thursday, Friday and weekends. Then, earlier in the weeks, or afternoons, they can run art house movies and attract a whole new audience.” There is also reduced pressure on film prints wanted by the distributor who may need to ship it out to Orange or Oodnadatta. Copyright AIST itself handles the dubbing to hard drive, so it becomes a subsidiary and complementary form of release. To illustrate this, Case recalls a typical film — The Queen — in 2007. This went out on about twelve 35mm film copies, which went into metropolitan centres, added to which were about forty digital copies. These were encoded into an MPEG format, compatible with ec2. If a film is supplied as a film master, AIST can make digital copies or transfer to film. What do you do about copyright protection? Case: “When digital release started people were more concerned with getting their film out there than they were with copyright protection. Hollywood is, as you know, fairly neurotic about the level of copyright protection because there is significant money to be made — and because if it’s a Hollywood product — it’s all about the first week’s returns. “With the sort of typical art house product, it tends to be a different audience. The audience is not disappointed if it doesn’t get to see it on Day One and the distributors are just anxious to get the thing out there. You know AIST copyright would not incur a big haemorrhage of revenue. But now we’ve got ec2 established, we’re looking to some form of encryption.” The company has dealt with “a couple of hundred cinemas around the country, more so in the provincial centres. Most of these are independentlyowned, although the Reading and the Dendy cinemas along with the Palace chain have a few digital installs. So cinemas have retained their 35mm projectors and will for some time. In Case’s view “The issue as far as the mainstream cinema is concerned is the enormous cost — we are talking up to $200,000. It’s coming down but it’s not coming down that quickly.” siliconchip.com.au The financial challenge for cinemas, especially independents, is that it’s not a matter of ‘either/or’, it’s a matter of ‘plus’. Cinemas already have 35mm projectors installed. Case: “They are usually paid for, amortised and they are churning on. If you’re putting in a new cinema you can’t afford just to put a digital projector in, you’ll be putting film in as well, so it’s an additional cost. The exhibitor gets nothing extra.” VPF Again Case sees the Virtual Print Fee as an anchor around forward-looking operators. He recalls that in the US it would take about eight years to amortise the cost of digital projection and ancillary equipment. Eight years is a long time to amortise the cost of digital equipment of any sort, especially with the high rate of changes in technology and rapidly falling costs. AIST is also pursuing 2K and 4K business. Case explains that they are just starting: “We’ve got the equipment for the encoding and the encryption.” Holdout About the only sector in the cinema game that would seem to be safe from a digital version would be the IMAX process. The 70mm film format has seen off many rivals in its 40 year lifespan and purpose-built cinemas around the world still show the enormous picture. What stands in the way of a digital IMAX format would appear to be the sheer size of the film frame: 69.6x48.5 mm. Transferred to digital, each frame would run to 70 million pixels. Twenty-four frames in each second would see the need to process 168 megapixels of image data. In view of this, it’s interesting to note that Hoyts cinemas plan to install IMAX theatres within three existing capital city venues. And these will use digital projection — but not with the same resolution or screen size as the film version. Surely, an admission that a full IMAX frame would defeat digitisation? But the surprising news is that, starting in mid-2008, all new IMAX projectors will include digital DLP technology and eliminate the need for elaborate film-based projector setups currently found in IMAX theatres. Anti-Piracy It is no secret that Hollywood has been concerned about movie piracy for a long time. On the morning following the world premiere of Phil Noyce’s “The Ugly American” in Hanoi pirate DVD copies were on sale throughout the city, captured by an audience member and his/her camcorder. One trade association claims a camcorder copy of a movie can be the source of more than 90 percent of all illegal copies during initial release. David Sanderson explains that every movie is 128-bit encrypted on the medium delivered to the cinema. If you intercepted an encrypted hard drive containing a movie and tried to play it, it won’t play: “Even if you set up a full digital cinema, you couldn’t play it. You need to have the KDM that is supplied with it. That KDM will only allow the movie to be played at a particular site, as in a multiplex, one particular multiplex between certain dates — and you try to do it any other time, it doesn’t work, so that makes the distribution side very, very secure. “If you are going to take your video camera and set it up in the back row of the cinema and record the movie off the screen, then it’s very high risk, because both the image and the audio track now have watermarking on them. If needed, the movie’s distributor can go back and find out exactly which cinema it was actually shown in.” Even when the movie is burnt to a DVD, the forensic watermark can still be detected and the cinema that showed the movie can be pinpointed as well as the date and time of projection. More info on watermarking: www. techweb.com/wire/192201447 Acknowledgement: Barrie Smith would like to thank David Sanderson and David Hill of Kodak and Dominic Case and Ben Wilson of AIST for their considerable help and assistance in preparing this SC story. December 2008  25 SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: dicksmith.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: dicksmith.com.au Monitor, display and log up to six sensors and display up to 10 readings! Pt.1: By MAURO GRASSI Multi-Purpose Car Scrolling Display This project started out as a digital dashboard display but has grown and can be used in any measurement or data logging application where you have 9-12V DC available. It can monitor up to six signals and display up to 10 computed values in a scrolling or static readout on a 7 x 15 dot matrix LED display. S O WHAT’S A SCROLLING DISPLAY? You really need a short video to show what this project does. The readout continually “scrolls” from left to right, displaying one, two and up to 10 computed values from up to six different signals. Each value is pre28  Silicon Chip ceded by its description, such as battery voltage, temperature, duty cycle and so on. If you want to focus on one reading, pressing the sole pushbutton will make the display static. Anyway, let’s just give a sample of what this project can do: • Measure Engine Temperature – have a relay switch on above a preset temp­ erature. • Measure Fuel Injector Duty – have a relay switch if the duty cycle is too high or too low. • Measure Engine RPM – have a relay siliconchip.com.au BATTERY SENSE Pin 1 of CON1 7 x 15 DOT MATRIX DISPLAY LDR SENSE Pin 13 of CON6 VIA CON6 SIX ADC INPUTS FOUR ANALOG/ RESISTANCE INPUTS CON3 TWO FREQUENCY/ DUTY CYCLE INPUTS CON2 S1 Pin 7 of CON6 (PUSHBUTTON) PIC 18F4550 MICRO CONTROLLER TWO CCP INPUTS USB PORT TWO RELAYS/ BUZZERS CON4 TWO DIGITAL OUTPUTS Fig.1: block diagram of the Car Scrolling Display. A PIC 18F4550 microcontroller is at the heart of the project. It processes various inputs, drives the dot matrix display, manages the USB connection and drives the two outputs. switch on at a preset RPM (perhaps to indicate when to change gear). • Measure Throttle Position and Delta Throttle Position – if the accelerator pedal is pressed too abruptly, a relay can be made to switch on this condition. • Measure Speed – have a relay switch if the speed is too high or too low. • Measure Fuel Tank Level as a percentage of full tank – have a relay switch on or off if the level is too high or too low. • Measure Battery Voltage – have a relay switch on if the voltage is too high or too low. • Measure Air/Fuel Ratio – have a relay switch on if the mixture is too rich or too lean. • Measure Cabin Temperature – switch on a fan via a relay if it is too high. • Measure almost any signal coming from the ECU. So pick any six of the above possibilities and that is what this project could do in your car. But that is just for applications involving cars. In reality, this project can be used anywhere where a DC supply from 9-12V is available or you have a computer with a USB port. It accepts voltage, resistance, frequency or duty cycle inputs and has two digital outputs for switching on limit conditions. We will siliconchip.com.au bet that you can think up lots more potential applications. The project itself uses two PC boards stacked with red Perspex on top. The top (display) board has a group of three 7 x 5 dot matrix displays, a USB port and a single pushbutton. The main (lower) PC board has the microcontroller and all the supporting circuitry for the connections and the optional output connections to relays or buzzers. To build and set it up, you will need a laptop or desktop computer with a spare USB port. You will use Windows-based software (downloadable from www.siliconchip.com.au) to set the measurement functions, calibrate the sensors and do data logging. The LED display can be dimmed (either automatically by sensing the ambient light level or manually) and you can select the scrolling speed of the display, as well as the names of the measurements and their units. In static mode, the LED readout can display up to four digits. It can also be turned off using the front panel pushbutton. The two output channels can drive external 12V relays directly and can be programmed to respond to maximum and minimum settings for any of the measured variables. Alternatively, the outputs could drive buzzers to give an audible indication that signals have exceeded their programmed limits. You can choose different sounding buzzers to indicate maximum or minimum conditions, when using two different buzzers. Or you can use only one buzzer and the maximum and minimum limits are indicated by different sequences of beeps. When you only need a visible indication of a limit condition, there are visible cues (a flashing display for a minimum condition and an inverted display for a maximum condition) on the LED display when in static mode. So there are many uses for this display and it’s really up to you as to how you set it up. User operation User operation of the Car Scrolling Display has been kept deliberately simple. There is just one pushbutton on the front panel (S1), a momentary SPST switch. The firmware recognises a short press and a long press. A short press is anything less than about a second, while a long press is anything more than that. There are three display modes. You switch to the next display mode by holding S1 pressed for more than a second, ie, by making a long press. The first is the Scrolling Mode where only the selected reading is continuously displayed as a scrolling string. In this mode, pressing S1 for less than a second (ie, a short press) will take you to the next reading, and that will then scroll continuously. After you have scrolled to the last December 2008  29 The unit is built on two PC boards – a main board and a display board. These are stacked together, along with a red Perspex panel for the dot matrix displays (assembly details next month). Note that the boards shown are prototypes and the final versions are slightly different. reading, making a short press will turn the display off. The sequence can then be repeated. The second display mode is the Static Mode. In this mode, the selected reading is displayed without scrolling. You can make a short press to go to the next reading. Again, making a short press after the last reading turns the display off. The sequence then repeats again. The third and last display mode is the All Scrolling Mode. In this mode, all readings are displayed as a scrolling string. The string then repeats continuously. Pressing S1 while in this mode takes you to the first display mode again and the whole sequence repeats from there. In both scrolling modes, the name of the variable, the value and the unit are displayed as a scrolling string. In Static Mode, up to four digits are displayed at once. In Static Mode, a maximum condition is indicated by the display flashing every second or so between normal and reverse modes, ie, all the normally lit dots become unlit, and vice versa – Fig.5. This is a very dramatic mode to indicate a problem condition. A minimum condition, on the other hand, 30  Silicon Chip is indicated by a flashing reading. As indicated, these visual cues are only available in Static Mode. Note that the Battery Voltage is always displayed first. For each of the displayed variables, you select the variable number and the value index to display. You also set the order in which they are displayed. Remember that you can change all settings and perform the required calibration using a laptop and a USB cable. Electrical signals in cars To get a good understanding of the signals used in cars, you will need to refer to the SILICON CHIP publication “Performance Electronics for Cars”. This has a range of useful electronic projects for cars and also explains how to intercept the signals from your car’s ECU. All modern cars have an ECU (Electronic Control Unit) that manages the ignition timing and fuel injection. Almost all electrical sensors in your car produce a voltage or vary their DC resistance, depending on the quantity being measured, or produce a digital signal (varying the frequency or duty cycle) to indicate the reading. Different sensors have different voltage ranges. For example, a narrowband air/fuel sensor may have an output in the 0-1V range, whereas a tachometer sensor output may be a square wave at 5V with the frequency of the signal proportional to the engine’s RPM. By contrast, a fuel injector signal is digital (12V amplitude), with the positive period (ie, the time the signal is at a high level) normally proportional to the time the injectors are firing. Alternatively, it may be inverted, with the negative period indicating the firing of the injectors. Since all calibration is done in software, either negative or positive duty cycles can be monitored. This project will accept all of these types of signals and with software calibration via the USB port, it is easy to adapt to a wide range of different sensors. How it works The block diagram of Fig.1 shows the main features of the circuit. As you can see, a microcontroller is the heart of the project and it drives the dot matrix displays, manages the USB connection and drives the two outputs. siliconchip.com.au Fig.3 shows the circuit of the main board while Fig.4 shows the circuitry of the display board. In Fig.3, IC1 is the PIC18F4550 microcontroller and there are four multi-way terminal blocks. CON1 (4-way) provides the connections to the battery or DC supply. The 12V input from the car’s battery is passed through a 10Ω 1W resistor and a reverse polarity protection diode (D1). The 10Ω resistor will normally drop around 2V since the circuit typically draws around 200mA, depending on the display brightness and the number of lit pixels. A 16V zener diode (ZD1) clamps the input voltage in case of transients. This is necessary to protect both the input supply bypass capacitor (470μF, 25V) and the 3-terminal low-dropout regulator REG1 (a LM2940-5). The entire circuit runs from the +5V rail output by REG1. This supply rail is bypassed by a 47μF 16V capacitor and the 100nF monolithic capacitors near the microcontroller and the other logic ICs. CON2 (4-way) accepts the two identical frequency/duty cycle inputs. Considering pin 2 of CON2, for example, the signal is applied to the base of NPN BC337 transistor Q19 through a 33kΩ resistor. The 10kΩ resistor to ground sets the switching threshold to around +2.6V. That is, the transistor switches on when the signal input is above +2.6V and switches off for voltages below that. Diode D5 clips any negative voltage excursions of the signal to the base of the transistor to around -0.6V. The collector output of the transistor is pulled up by a 10kΩ resistor and is fed to the CCP1 (Capture/Compare) input (pin 17) of IC1 via a low-pass filter composed of a 1kΩ resistor and a 10nF capacitor. This low-pass filter removes potentially noisy signal transitions. The frequency and duty cycle of the input signal is measured by capturing the value of an internal timer run from the microcontroller’s system clock (12MHz). It counts how many system clock ticks occur when the signal is low and when the signal is high. TYPICAL DISPLAY READOUTS siliconchip.com.au The counter is 24 bits wide. For example, when applying a 40% duty cycle rectangular wave at 100Hz, we will obtain the following counter values: CHigh = 48,000 and CLow = 72,000 In other words, the internal timer running from 12MHz counts up to 48,000 in the time that the signal is high and up to 72,000 in the time the signal is low. From these two values, the firmware calculates the frequency and duty cycle as follows: Freq = 12,000,000/(CHigh+CLow); and Positive Duty Cycle = 100CHigh/(CHigh+CLow) Voltage/resistance inputs The four voltage/resistance inputs are connected to the 6-way connector CON3. Each analog input passes through a voltage divider consisting of 22kΩ and 10kΩ resistors and bypassed by a 100nF capacitor. Each resulting voltage is then digitised by the microcontroller using the onboard ADC (analog-to-digital converter) which has 10 bits of resolution and whose full range is from 0-5V. The division factor from the 22kΩ and 10kΩ resistors is 3.2 which means that the analog inputs have a full range of 0-16V, suitable for most applications in a car or any vehicle with a 12V battery. Any voltages above 16V will not be correctly read (ie, readings will plateau), because the input protection diodes on the ADC inputs of IC1 will begin to conduct. The high series input impedance will ensure that the input Fig.2: these diagrams illustrate some of the readouts that can be scrolled across the three 7 x 5 dot matrix displays. The battery and ambient light functions are built in, while all other functions are set-up by the user via a PC program. December 2008  31 +5V 100nF 100nF 11 32 Vdd Vdd AN5 10k 1k CON2 FQ1 FQ2 GND 33k 2 C B K 3 10k 1 E D5 Q19 BC337 17 47 µF 16V 1k CCP1 RE2 RE1 100nF 8 10k 10 9 10nF D7 MCLR/Vpp K 1 A A +5V PGD/RB7 PGC/RB6 10k 1k 33k B K 10k C E D6 Q18 BC337 16 IC1 PIC18F4550 10nF RA4 RB5 RB4 RB3 RB2 RB1 CON3 AN3 AN2 AN1 AN0 GND 1 2 RB0 4 x 22k 5 3 4 4 3 5 2 6 RD7 AN3 RD6 AN2 RD5 AN1 RD4 AN0 RC7 RC6 10k 100nF 10k 100nF 10k 100nF 10k 100nF RD2 RD0 D+ D– RC0 13 X1 20MHz 22pF RD1 OSC1 AN4 RD3 14 22pF OSC2 VUSB Vss 12 SC 2008 CAR SCROLLING DISPLAY 39 CCP2 A +5V 40 Vss 31 6 38 37 36 35 34 33 30 29 28 27 26 25 21 19 24 23 15 20 7 22 18 1 µF 16V 1 µF 16V 10k MAIN BOARD Fig.3: the main board circuitry. PIC microcontroller IC1 accepts the various analog and frequency input signals, processes these signals and then drives the separate display board via connector CON6. itself is not damaged. The downside of having a large dividing factor of 3.2 (16V = 5V x 3.2) is that you lose resolution in the ADC conversion. Since the ADC is 10 bits 32  Silicon Chip or 1024 levels, we obtain a value of 16V/1024 or about 16mV sensitivity. While this is plenty for most applications, you can increase the sensitivity of the input if you know in advance that your sensor has a nominal output much lower than 16V. This involves changing the 22kΩ resistor on the corresponding analog input. The following equation is used siliconchip.com.au D1 REG1 LM2940-5 OUT K IN GND A 10 Ω 1W +12V 100nF A 56k ZD1 16V 1W 2 1 (BATTERY SENSE) CON4 A 1k C B 2 A Vpp GND 6 1k C B AUX 4 PGD 5 PGC RLY1 1 D3 Vdd 3 RLY2 3 2 K K (ICSP) 1 4 D2 Q16 BC337 E +5V 4 3 K 470 µF 25V CON1 E Q17 BC337 220 µF 50V TO CON7 ON DISPLAY BOARD CON5 CON6 +5V 6 24 23 1 2 3 4 5 7 22 8 9 10 11 12 14 21 26 20 16 25 27 13 17 K D4 A 1.5k A 18 19 GND K D1-D3: 1N4004 BC337 A B E A to get an approximate value for the resistor: R = 2000V - 10,000 where V is the maximum voltage range required (>5V) and R will be the new siliconchip.com.au GND K ZD1 C LM2940-5 IN K GND Oxygen sensor loading Although the ADC inputs of IC1 have a high input impedance, the load on the analog inputs will be the sum of the 22kΩ (or your replaced value) resistor and the 10kΩ resistor, ie, 32kΩ (or 10,000 + R). While this loading is high enough to result in very small current draw from most sensors in your car, you should be aware that typical narrowband oxygen sensors do not tolerate more than about 10μA current load. Since the ECU will have its own current load, we should aim to draw no more than about 1μA extra from such a sensor. This means that if you wish to connect an oxygen sensor to this project, you should omit or remove the 10kΩ resistor to ground on the corresponding analog input. The result will be that the loading will then be the series impedance of the 22kΩ resistor and the high input impedance of IC1’s ADC input. The resulting extra current should be less than 1μA since the ADC inputs have a typical leakage current of just 500nA. Note that there will also be negligible transient loading due the 100nF capacitor. Additional input channels 15 D4-D6: 1N5819 D7: 1N4148 sensitivity will be about 6mV and the resistor value will be 2kΩ. Since all calibration is done in soft­ ware, you only need to replace the 22kΩ resistor corresponding to your analog channel to improve the accuracy for that channel. The software does not need to be changed, as the values will be correct for your new divider when you perform the next calibration. OUT resistor value (ie, to replace the existing 22kΩ resistor). The resulting sensitivity will be approximately the value of V in mV (millivolts); eg, if V = 6, then the There are two additional analog channels used. One is used to measure the battery voltage at pin 1 of CON1. It has its own 56kΩ and 10kΩ voltage divider and 100nF bypass capacitor. The other analog channel is used to monitor a voltage divider on the display board consisting of a light dependent resistor (LDR1) and an 82kΩ resistor. The analog signal is at pin 13 of CON6 and is used to measure the ambient light level, to vary the brightness of the LED display. CON4 is used to connect the relays and/or buzzers used for the limit conditions. Each digital output from the microcontroller is applied to the base of an December 2008  33 CON7 3.3 +5V Q1 6 470F 16V B 15 x 680 1 Q2 E Q7 E B C +5V E B C Q8 Q15 E B C B C E C 2 3 4 21 5 22 23 9 24 10 25 26 8 27 C1-C15 1 17 16 20 19 12 1k 12 11 13 Sin 16 1 16 Vdd Q0 Q1 Q2 Q3 MR 14 CK C15 9 100nF 10 14 C7 +5V G 11 SER C8 4 C2 C1 USB TYPE B SOCKET 1 2 3 3 IC2 Q4 4 74HC595 5 4 Q5 6 Q6 7 Q7 9 So LCK SRCK OE 15 2 15 12 LED ARRAY 3 B +5V E C Q1 – Q15: BC327 11 6 Vss 10 7 LDR 13 LED ARRAY 2 13 5 8 LED ARRAY 1 14  LDR1 S1 IC3: ULN2003 8 S1 7 82k 1k GND 15,18 SC 2008 CAR SCROLLING DISPLAY DISPLAY BOARD Fig.4: the Display Board circuit. It uses a 74HC595 shift register (IC2) to drive the rows of the three dot-matrix LED arrays via a ULN2003 Darlington array (IC3). Transistors Q1-Q15 switch the display columns. NPN BC337 transistor (Q16 or Q17) via a 1kΩ resistor. Each transistor is configured as a switch, to drive the coil of the relay or a 12V buzzer. Diodes D2 & D3 clip any back-EMF spikes generated when the relays switch off, while the 220μF 50V capacitor is used for bypassing. The microcontroller (IC1) runs from a 20MHz crystal and the two 22pF ceramic capacitors provide the correct loading. The 1kΩ resistor from the 5V 34  Silicon Chip rail is used to pull up the MCLR-bar input (pin 1) of the microcontroller (this is the active low reset input). The microcontroller is reset by internal POR (power on reset) circuitry. CON5 is optional unless you fancy doing your own programming using the PicKit2 programmer from Microchip. We used this during development of this project. You will not normally need to use this connector. There is one further sub-circuit on the main board, consisting of a Schottky diode D4 and two resistors (10kΩ and 1.5kΩ). Pin 17 of the 27-pin connector CON7 is the VUSB rail (ie, positive power from the USB port on the display board). This will be around +5V when a USB cable is connected and 0V otherwise. This input passes through the voltage divider consisting of 1.5kΩ and 10kΩ resistors. The division factor is thus 1.15 meaning that pin 22 of IC1 siliconchip.com.au will be at around 4.3V when a USB cable is connected and at 0V otherwise. This pin is configured as a digital input (bit 3 of PORT D) which allows the firmware to detect when a USB cable is connected or disconnected. Schottky diode D4 allows the circuit to be powered directly from the USB port and connects directly to the +5V rail. In the worst case, the VUSB line will be at +4.75V (5V ±5% is what the USB standard specifies) and so the +5V rail can be as low as +4.5V when powered directly from the USB port. D4 also protects against reverse polarity and prevents current flow into the USB port when the circuit is powered from a 12V battery or power supply. Because the +5V rail can be substantially lower than +5V when powered from the USB port, you MUST perform any calibration with the full 12V input from the car battery. The actual voltage of the +5V rail will affect the ADC readings from the analog channels because it is the positive reference for the ADC conversion. This will be explained in the calibration instructions, next month. Display circuit Microcontroller IC1 controls the display via 27-pin connector CON6, which plugs into CON7 on the display board – see Fig.4. Fifteen of these lines control BC327 PNP transistors to drive the columns of the LED display. The display board consists of three dot matrix LED modules, a 74HC595 shift register (IC2) and a ULN2003 Darlington driver (IC3). The display is multiplexed, meaning that only one column is lit at any one time. The brightness of the display is varied by changing the duty cycle of the column driving signals. The display refresh frequency is around 150Hz. IC2 is an 8-bit shift register and the seven least significant bits (Q0-Q6) are used to drive the seven rows of the display. The microcontroller uses three lines – SER (data input), G-bar (output enable) and CK (clock) – to load each row value into IC2. The G-bar (enable) line forces all outputs of the shift register to go tri-state. This effectively blanks the display. This is done by the microcontroller when the display is being refreshed or when the shift register is being loaded. The time that the display is disabled is so short it is impercepsiliconchip.com.au Main Features & Specifications • • • • • • • • • • • • • • • • • • • • • Can be powered from 9-12V DC or from a USB port (5V). Two Frequency/Duty Cycle Inputs with frequency up to 10kHz. Positive Duty Cycle Range: 0-100%. Four Voltage/Resistance Inputs Plus Battery Voltage (the latter has its own channel). Voltage Range: 0-16V (greater or smaller ranges possible by changing one resistor). Sensitivity with 16V scale: approx. 16mV. Best Sensitivity: approx. 5mV (requires changing one resistor and recalibrating using the supplied PC software). Two output channels to drive external relays or buzzers. Up to 10 displayed variables. Averaging or direct acquisition mode for each variable. Screen dimming on ambient light with adjustable sensitivity and selectable minimum brightness. 7 x 15 dot matrix LED display (scrolling or static display). Static display of up to 4 digits (floating point) Selectable scrolling speed. On screen limit warnings for each variable in the static display mode. Software calibration using polynomial interpolation. Persistent settings stored in non-volatile memory. Easily load and store previous settings to file on your computer. Easily load and store different calibration point files on your computer. All settings changeable using the USB port and PC host program. Data logging via the USB port; selectable variable update frequency from 0.1-8Hz; can collect 1000s of samples to a PC’s hard drive. tible. The SER (data) line feeds the data into the shift register and is also controlled by a simple digital output of the microcontroller. The seven bits from the shift register are used as inputs to the ULN2003 Darlington array (IC3). The ULN2003 can sink up to 500mA in total between its seven outputs. Note that there are no current limiting resistors to the displays. Instead, we rely on the beta limiting of the transistors via the 680Ω base drive resistors. We found that even smallvalue limiting resistors markedly decreased the perceived brightness of the LED display. However, we have included a 3.3Ω current-limiting resistor on the supply rail to the entire display board. Because the display can draw substantial currents (up to around 300mA peak), thereby affecting the +5V rail used for the positive reference to the ADC system, the firmware also turns off the display when digitising the analog Fig.5: in-range measurements appear as shown at left, while out-of-range measurements alternate between normal and reversed mode (top right) when above maximum or flash on and off when below minimum. inputs. This happens too quickly to be perceptible. An additional digital input on IC1 is used for pushbutton switch S1. It will be high when S1 is pressed and low otherwise. The signal is fed via CON6 at pin 7 and the switch is de-bounced by the software. The USB type B socket is on the display board and the four connections are fed to the main board via CON6. That completes the circuit description. Next month we give the full constructional details and set-up proSC cedure, as well as the parts list. December 2008  35 Test the SALT CONTENT Do you have a swimming pool with a salt-water chlorinator? Then you will know that you have to periodically add salt to the water to make sure that the chlorination process works properly. So how do you measure salt content in your swimming pool? By LEO SIMPSON T hese days, many in-ground swimming pools use a salt-water chlorinator to keep the water clean and safe from nasty microbes. The chlorinator electrolyses the salt content of the water to produce sodium hypochlorite which then acts like normal “pool chlorine” to sanitise the water. Not having large amounts of chlorine in the water makes it much more pleasant and you don’t come out of the water smelling of chlorine. Nor will your eyes sting or your swimming togs become bleached. However, for a salt-water chlorinator, there must be a minimum concentration of salt in the water for it to work correctly. Just how much is needed depends on the brand and model of chlorinator but typically it is around 3000 to 4000 ppm (parts per million). If the salt concentration goes below the specified level, you must add some salt to the pool. On the other hand, you should not The Pool Salt Meter at our local pool shop. Obviously, it does more than check dissolved salt levels – it also checks total dissolved solids. But it also costs more than $300 and, according to our friendly pool shop owner, “ . . . costs a fortune to repair, too.” We wonder why! 36  Silicon Chip add too much as that is simply wasteful and it might lead to accelerated corrosion of some of the pool hardware. So how do you measure salt water concentration? Most people don’t even bother. They just take a sample of their pool water to the pool shop and ask them to test it (at the same time getting several other important pool chemistry factors checked). If it is below the specified level, this is the perfect opportunity for the pool shop to sell some bags of salt. A couple of shots of the measuring cup to show not only its size but also its construction. The two black circles (next to the green circles) are the carbon electrodes which make contact with the pool water, to give a reading in parts per million on the meter at left. siliconchip.com.au of your swimming pool Here’s our lo-tech – but almost as good – version, total cost 87c (we had to buy the salt!). The rest of the “bits” were from the junk box or test bench. This shot is with tap water, for reference – the multimeter reads 4.42kΩ. The pencil “level” mark inside the tube ensures consistency of measurement. You may note the little puddle of water at the base of the tube: it’d be a good idea to give both the end cap and screw heads (outside the tube!) a smear of silicone sealant to stop this happening! So why not make your own salt meter? Such a device is not likely to be very complex, is it? That’s what we thought too. So we visited a local pool shop and asked the friendly manager if we could have a look at his salt meter. And we took some photos to show It’s not really that hard, is it? We don’t think so! (This is the warning label on the meter at left). siliconchip.com.au what it looked like. It was an analog meter with scale calibrations in ppm and TDS (total dissolved solids). But notwithstanding those obscure labels, our impression was that it was simply an ohmmeter connected to a measuring cup. Measuring cup The measuring cup was interesting. As the pictures show, it was a small cylindrical container with two holes at a certain level up the sides. In the base of the cup were two carbon electrodes which evidently make connection to the solution. In use, the cup is first flushed with fresh water and then, holding your fingers over the holes in the sides of the cup, you fill it up with your pool water. You then unblock the holes and the water flows out so that it is at a precise level in the cup. You then take the reading by pressing the button on the meter. That’s all there is to it. Hmm. So is this really necessary? Since virtually every reader of SILICON CHIP magazine has a multimeter or two or three, whether a digital (DMM) or good old-fashioned analog type and since they all have “Ohms” scales, no other equipment is necessary. In other words, if you want to measure salt content of your pool, you don’t need a $300 salt solution meter or whatever else it might be called. Standard salt solution. What you do need is a salt solution of known concentration. To be more December 2008  37 precise, how do you make up a solution with 3000 ppm salt? In fact, making up such a solution is dead easy. All you need is a measuring jug which will hold one litre of water and a set of measuring spoons. Then you need to measure out 3 grams of salt. Pool salt or table salt will do – they are both pretty much the same thing, no matter how they are labelled. Half a teaspoon of salt is 3 grams. Add that to the water and stir thoroughly until all the salt is dissolved. Voila! You now have one litre of salt solution which is exactly 3000 ppm. Hardly a high-tech exercise, is it? Want a 4000 ppm salt solution? Add 4 grams to your one litre of water instead of 3. But believe it or not, we have seen internet retail outlets which sell such a standard 3000 ppm salt solution for $10.95 for a 230ml bottle! So now that we have a standard salt solution, how do we measure salt content in a swimming pool? It is just a matter of comparing the resistivity of the standard salt solution with the resistivity of the pool water. The more salt in the water, the lower will be its resistance. So the next step is to make a container with a couple of electrodes connected to both sides. You could use almost any cylindrical plastic container but we chose to use a 200mm length of 90mm plastic stormwater pipe fitted with a standard end cap. We drilled 2.5mm holes in opposite sides of the resulting container about 140mm from the bottom. We then attached a solder lug to each of the holes, using a screw, nut and lockwasher. The solder lugs were connected to a length of figure-8 cable with a pair of 3mm banana plugs at the other ends. The banana plugs were connected to a digital multimeter and it was switched to measure “Ohms”. A dollop of silicone sealant should be applied to the screw heads (on the outside only!) to make them watertight. While you’re about it, you might like to put a smear of silicone on the inside bottom of the 90mm tube as you slide the cap on – again, to make it watertight. We didn’t and the results are obvious in our photograph. So that is the test set-up. Checking it out To check it out, first fill the container with fresh water to a mark at, say, 20mm from the top. Note the ohms measurement. Typically our reading was 5000 ohms or thereabouts. It will vary depending on how much chlorine is in your tap water. Tip out the fresh water and note that the resistance reading now becomes very high, typically 40 megohms or more. Then fill the test container with the 3000 ppm salt solution and note the resistance reading. Typically, we measured around 1800 ohms or 1.8kΩ. This will vary depending on the temperature of the solution but we can assume for the purpose of this exercise that the solution water temperature is fairly close to that of the pool. Then fill the test container with water from your pool. If the salt con- centration is more than 3000 ppm, the resistance reading will be lower than 1.8kΩ (or whatever your previous measurement was. Conversely, if the salt concentration is less than 3000 ppm, the resistance will be higher than 1.8kΩ. You can then decide whether or not you need to add salt to your pool. Incidentally, you should not need to add salt to your pool more than once or twice a year. Evaporation from your pool will not reduce the salt concentration; it will increase it. There are only three ways in which salt can be lost from your pool. The first is when swimmers splash water out of the pool and you subsequently have to top it up with fresh water. Second is when back-washing the pool filter, although our experience is that this doesn’t make a huge amount of difference. The third way – fortunately rare because it usually throws virtually all your pool chemistry out of whack – is when you get a lot of rain and a lot of water is lost out of the overflow. Of course, if your pool leaks more than average (most do leak a little!) and you often have to add water to top up the level, your salt level will also drop. So there it is. While we have not described how to make a salt concentration meter reading in ppm (because we don’t believe it’s necessary to actually know the figure), we have described a method of comparing the resistivity of pool water to a standard salt solution. SC www.rmsparts.com.au SMART PROCUREMENT SOLUTIONS o Resistors o Relays o Capacitors o Buzzers o Potentiometers o Switches o Crystals Tel: 07 3219 4735 Fax: 3219 4716 o Connectors o Semiconductors o Hardware o Optoelectronics o Chemicals & Fluxes sales<at>rmsparts.com.au  38  Silicon Chip WHOLESALERS  DISTRIBUTORS  KITTING SOLUTIONS  siliconchip.com.au PRODUCT SHOWCASE In-dash car computer has it all – even WinXP! The GIZMOSIS INFILL G4 in-dash car computer has recently been beefed up to now include a sizable 120GB hard drive and 1GB RAM. As well, the reversing camera (previously an option) is now included as standard. It runs a full version of Windows XP so it can accommodate any software that you can run on your laptop.The 6.5-inch wide touch screen allows easy access to all features or alternatively the unit can be voice operated. With a mobile broadband USB modem plugged in, you can be connected to the world! Emails arrive and can be read on screen or aloud in a human voice. Replies can even be sent by dictating back, without ever taking your eyes off the road. A GPS receiver is built into the unit to provide easy navigation. View in 2D or 3D mode and choose from hundreds of points of interest. Using Bluetooth to connect to your mobile phone, you can easily make and receive calls via the G4. Signal strength and battery level are displayed on screen. And being a fully integrated unit, the volume of the radio is automatically lowered to allow for voice calls or navigation instructions to be clearly heard. The system also supports WiFi, so you can connect to a hotspot or transfer files into the car from your network. An option is also available to connect the GIZMOSIS INFILL G4 to your vehicle’s internal computer and receive real time engine diagnostics. Free Mini Cooper at RS! Just in time for Christmas, RS Components have a present for their customers. Spend $400 before the end of January 09 at the trade counter at RS and they’ll give you a remote control Mini Cooper. Or spend $250 and get a multi-function pocket knife. Contact: Contact: PO Box 404, Elsternwick, Vic 3185 Tel: 1300 449 667 Fax: 1300 880 104 Website: www.gizmosis.com.au 25 Pavesi St, Smithfield NSW 2164 Tel: (02) 9681 8558 Fax: (02) 9681 8614 Website: www.rsaustralia.com Gizmosis RS Components ANTRIM Gecko Soundbase for iPod also a smart AM/FM Clock Radio The Gecko Soundbase Stereo Sound System and Radio for iPod features two full-range speakers, two tweeters and two internal bass ports to deliver crisp, room filling quality sound. And the fun doesn’t stop with your iPod or iPhone. The Soundbase is also an AM / FM clock radio with eight programmable memory settings. It features a retractable iPod dock tray that can be opened and closed with one simple push. And it is the first Australian iPod Sound System Ozitronics Tel: (03) 8677 1411 Fax: (03) 9011 6220 Email: sales2008<at>ozitronics.com New voice recorder kits using ISD1700 series ICs The sampling frequency can be set from 4kHz to 12kHz with external resistor, giving greater flexibility in duration versus recording quality. Non-volatile storage. Standalone or microcontroller (SPI) operating mode. All inputs & outputs via standard connectors. Onboard microphone. K188 (40 sec)....$46.20 See docs for details K189 (120 sec).. $49.50 More kits and all documentation available on website: www.ozitronics.com siliconchip.com.au TRANSFORMERS manufactured in Australia by Harbuch Electronics Pty Ltd harbuch<at>optusnet.com.au Toroidal – Conventional Transformers Power – Audio – Valve – ‘Specials’ Medical – Isolated – Stepup/down Encased Power Supplies to include an infra-red remote that can control the menus on your iPod and iPhone. The remote control lets you navigate through your iPod or iPhone’s menu system giving you complete control over your playlists, songs, artists and albums, all from the comfort of your chair. The Gecko Soundbase is now available for $179 RRP. Contact: Powermove Distribution 14 Centofanti Pl, Thomastown, Vic 3074. Tel: (03) 9464 4999 Fax: (03) 9464 7799 Website: www.powermove.com.au Toroidal General Construction OUTER INSULATION OUTER WINDING WINDING INSULATION INNER WINDING CORE CORE INSULATION Comprehensive data available: www.harbuch.com.au Harbuch Electronics Pty Ltd 9/40 Leighton Pl, HORNSBY 2077 Ph (02) 9476 5854 Fax (02) 9476 3231 December 2008  39 SERVICEMAN'S LOG Intermittents: No Money For Old Rope The increasing popularity of home-theatre systems has had one good effect from my point of view: a steady flow of home-theatre amplifiers to fix. Now that VCRs are all but gone, I need all the extra work I can get. We have had a number of audio repairs come into the workshop recently, all of which have been irritatingly difficult. The first was an Onkyo surround sound home-theatre system, model TXSR502, which was intermittently switching off. Unfortunately, the word “intermittent” often has different meanings for the customer and the repairer. To the former, it means that there obviously can’t be much wrong and therefore it will be cheap to repair an item that is actually working most of the time. To the repairer, however, it means quite the opposite. For starters, it is often difficult to get the fault to occur to order so that the symptoms can be observed. An intermittent fault can also make it difficult to judge whether or not the fault has been really fixed, so that the set doesn’t come back under warranty. Finally, tracking down an intermittent fault can be a time-consuming task and that adds to the expense. In addition, the unit has to be soak-tested for longer. Unfortunately, the difference between these two positions usually has to be resolved into an estimate before you can start the job. And if guesswork is to be eliminated, you literally have to repair the set first, otherwise you could be hopelessly out. Of course, you can always reduce an estimate but rarely are you able to increase it. Fortunately, experience has shown that, after many years, the Onkyo TXSR502 can develop dry joints, especially in the pre-power amplifier driver stages. In fact, I had quickly 40  Silicon Chip concluded that the fault was probably due to the protection circuits switching the relays off, so this fitted in well with the known pattern of faults with this model. As it happened, the board had quite a few dry joints so I was fairly confident that reworking the solder across the PC board would fix the fault. Eventually, after I had finally completed the work, I reassembled the set and put it aside to soak test. Initially, all seemed well but my coffee fix had only just kicked in when, some 15 minutes later, I noticed that the same fault had started again. The speaker relays were clicking on and off and the set was locked onto the “Video 1” input and wouldn’t change. This meant that it just had to be one of the two microprocessors the set uses. The main one, Q7502 on the display board, feeds the DSP (digital signal processor) which then feeds the protection circuits. I could measure the voltage changing on the output ports and could also see the data lines varying between the processors. Being an Onkyo agent has its privileges and I was able to borrow another TXSR502 from another service agent. I then swapped the front display panels and found that the fault transferred from one set to the other. OK, so the fault was on the display board, even though there was hardly anything on it apart from its microprocessor. This microprocessor (Q7502, µPD780232GE-030) is an 80-pin high-density square surface-mounted IC. It’s terrible to replace but cheap as chips so I ordered a new one, plus the duo-crystal X7501. They arrived fairly promptly and took a long time Items Covered This Month • • • • • Onkyo Surround Sound Home Theatre TXSR502 Cambridge Power Amplifier Yamaha RXV363 Home Theatre Amplifier Panasonic TC-60P22A (MX8 chassis) Trio Model CS-2110 QuadBeam Oscilloscope to install but I was relieved to think that this would almost certainly fix the fault. Well, it didn’t! So what was there left that could cause this problem? I turned my attention to the 26 tactile switches but they all looked perfect, as did the three operation switches on board U03 which plugged into 3-pin socket JL7501. The keys form a matrix which feeds the microprocessor on four lines: K0K3 (pins 19-22). There should be +5V on these lines but in fact there was only 2V, so 3V was disappearing down the gurgler somewhere. I checked the impedance of the switch lines and noticed that K0 (pin 19) was slightly lower than the other. As a result, I disconnected it and the unit immediately worked properly but it stopped again when this pin was reconnected. Next, I unplugged the Operation Switch Board (U03) but that made no difference. I then resoldered the socket and scrubbed it with PC board cleaner and a toothbrush. That finally fixed the problem and it worked for week before it was returned to the client who no doubt thought he was paying an inflated price for what he considered a straightforward job. I can’t honestly put my hand on my heart and say that I know exactly what caused the problem. However, I surmise it to be either a solder dag or just dirt that produced a high resistsiliconchip.com.au ance between pin 2 (K0) and pins 1 & 3 (GND) of socket JL7501. In the end, I was happy enough to warrant this particular repair but despite my efforts, the customer’s attitude clearly insinuated that the job was money for old rope. Cambridge amplifier The second job was a Cambridge Power Amplifier which came in under warranty, the customer complaining of a loud “buzzing” noise in the loudspeakers. Well, obviously it wasn’t the loudspeakers that were at fault. Instead, it was either “buzz” from one of the three power supplies used in this unit or some sort of earth loop that was causing the problem. There are four modules in this unit, two of which are separate ±50V power supplies, one feeding each amplifier. Then there is a third power supply called “SNAPS” that feeds the preamps and drivers. Each module has its own separate earth and the problem only occurred when the XLR plugs were connected to the output amplifier. I began by using a CRO to check for hum or ripple on the various supply rails but these were all OK. Once again, being a dealer allowed us to use another set to swap modules over but that made no difference! It wasn’t until we spoke to technical support that a solution was found. In fact, a technical information bulletin had been released about the problem. This amplifier uses a toroidal mains siliconchip.com.au transformer with four 50V windings. These go to separate bridge rectifiers which in turn feed the power supply module for regulation, switching and protection. I did some checks and it all appeared to be working correctly, as all the voltages were spot on and there were no signs of ripple. The pairs of cables from the transformer were colour coded 2 x red, 2 x red and black, 2 x green and 2 x green and black. However, for some unknown reason, one of the red leads had been swapped over with a red and black lead in the factory. This meant that two of the bridge rectifiers were in fact sharing windings. The supply was only giving this weird instability symptom when it was plugged into the power amplifier. Why it wasn’t picked up during the final test in the factory I have no idea. Perhaps it was made on a Friday! Yamaha RXV363 amplifier The final amplifier that came in was a new Yamaha RXV363 hometheatre unit. It was apparently (but not quite) dead, so I went straight into a diagnostic mode by pressing “Audio Select”, “Straight Effect” and “Standby” altogether. When I did this, the unit initially reported “DC protect” on the LCD but it wouldn’t stay in this diagnostic mode. I then checked the voltages on the speaker output terminals with respect to ground and all five channels read -1.2V. Obviously, I was hoping for 0V, so this was puzzling. What’s more, if any of the amplifier output stages had gone short circuit, I would have expected its output voltage to be close to either +50V or -50V, ie, at one of the two power supply rails. The output IC amplifiers have -50V applied to pins 1 & 2 and +50V to pin 8. Sure enough, the voltages on pin 2 & 8 were correct, indicating that the ±50V rails were OK at these points but the -50V rail to pin 1 of each amplifier was missing. On checking the -50V power supply, I found the correct voltage coming out of the bridge rectifier but no -50V coming out of one of the regulators. Eventually, I found a 10Ω fusible resistor open circuit in the -50V rail. Replacing it fixed the problem. The mystery owner Some television repairs can cause havoc. I was having an uncharacteristically busy week and the workshop was absolutely full of jobs – up to the gunwhales. In fact, it was so full, I was working on some jobs just outside the warehouse door but despite the full workload I was steaming through it all and it was all falling into place. And then, about 1 o’clock, this bloke drops in a TV set belonging to a friend of his. He didn’t know her full name, address or telephone number but insisted she would phone shortly and give me all the information I needed. He then quickly disappeared. The set turned out to be a Panasonic TC-60P22A using an MX8 chassis and when I fired it up it gave a terrific picture on all channels. Three hours later the set was still going strong, noone had phoned and there was still no room inside the workshop! December 2008  41 Serviceman’s Log – continued Anyway, I removed the chassis and then released the PC boards from their frames. That done, I carefully examined the copper side of each board under a magnifying lamp but the soldering could not be faulted. I then checked the component side for any obvious faults but again everything looked OK. Next, I used my ohmmeter to check for continuity from the mains plug pins to the power supply in case of invisible hairline fractures. And it was here that I had my first clue. I was tracing the line between the neutral pin to the bridge rectifier and it soon became apparent that it was intermittently going open circuit. Step by step I eliminated it until I got to the power switch. The power switch is a double-pole double-throw (DPDT) type and when I removed and checked it, I could see that it was intermittent on one side only. Having found the problem, I put it back in the set, shorted the bad side and left it on test while I waited for the owner to get in contact. Unfortunately, I still hadn’t heard from her a fortnight later, so I’m not sure how long I now have to wait. One good turn . . . I tried the name, address and tele­phone number the mystery man had given me but none was correct. I then checked the telephone book and whitepages.com.au but again no luck. Great – someone had dumped a set on me with no fault given and no contact information. Well, at least I didn’t have to wait too long for the answer to one of my questions because about one hour later, the set suddenly died. However, the day was over so I just jammed the set inside the door and left. The next day was a hot one and the set conked out after a much shorter time period than the previous day. This indicated that the fault was heat-sensitive, so I hit various 3-pin IC regulators and other devices with 42  Silicon Chip freezer to see if it would start up again. It didn’t but when I tapped the chassis with the butt-end of a screwdriver, I could hear it trying to start. That was all though. When the set was dead, there was no red power LED which meant that there was no standby voltage. Despite the fact that there were lots of other jobs in the workshop, I decided to give this set some priority. By tracking down this intermittent fault, I could at least quote for it when (and if) its owner phoned and get it out of the way. By now, I’d concluded that the fault wasn’t heat related. Instead, it was more likely due to a bad connection or a dry solder joint somewhere near the power input stage of the power supply. I guess that you could call this story “One Good Turn Deserves Another”. It involves a guy in South Africa who discovered that his neighbour had fallen on hard times. Apparently, the neighbour’s electricity had been cut off and that meant, among other things, that the wife had to do all the washing (including nappies) by hand – this for a whole menagerie of kids. Being the kind-hearted type, he agreed to let his neighbour use an extension lead to connect their houses together so she could use the washing machine. That was fine for awhile and then our hero went out to do the week’s shopping. When he returned, he was surprised to hear this propeller-like whirr coming from his fusebox. On examining it, he found the electricity meter spinning so fast that the gauge was about to take off. Of course, he went straight around to his neighbour to find out whether they had anything to do with it. He didn’t have to ask because as he was going around the back, there were at least another half dozen extension leads leading from his house to all the other neighbouring ones. Talk about siliconchip.com.au doing a good turn! As you can imagine, that was one arrangement that came to a quick end. You also have to wonder about the ratings of the fuses in the fusebox. Trio CS-2110 oscilloscope The oscilloscope in my workshop is a Trio (Kenwood) Model CS-2110, a quad-beam instrument with a bandwidth of 100MHz on its two main vertical channels. It also features dual timebases which allow delayed triggering, with one timebase brightening the other at an appropriate time during the sweep. For its time (ie, late 70s early 80s), it was a high-end instrument and it is still capable of a great deal of useful work. In fact, I had used my scope for many years without problems but then it slowly developed an annoying focus fault. This fault was obviously temperature related because the scope needed to be left running for progressively longer periods after a cold switch-on before the focus control worked properly. When the scope was working properly, it was capable of a nice sharp trace but as time went by, it became increasingly difficult to achieve correct focus. Eventually, the time came to do something about it. Fortunately, I had a copy of the service manual and this included the circuit diagrams, waveforms, a troubleshooting chart and a component list. I began by undoing the four screws at the back of the case and sliding the chassis out. That done, I quickly identified the main switchmode power supply and after reference to the manual, I also identified the Power Blanking Unit (X68-1400-00). This latter board contains no fewer than six voltage sub-regulators plus the necessary circuitry to generate the high negative voltages for the tube cathode, grid and focus anode. It also generates the positive EHT for the main accelerating anode. I checked some voltages on this board and it soon became clear that the focus voltage was low at around -700V at cold switch-on before gradually increasing towards the specified -1200V as it warmed up. However, before I could get any further with my investigation, the main power supply failed completely. All the voltages dropped to zero and I have to admit that it may have been as a result of my putting a multimeter probe somewhere where it shouldn’t have been. The Switching Power Supply Unit (W02-0413-05) is a self-contained offline switcher of about 40W rating and fortunately the manual shows the circuit. A quick check showed that the in-line fuse was intact but despite this, there were no signs of life Most of the control and switching circuitry in the power supply is contained in a sealed module branded Sanken STK7308. I wondered if the module had protected the fuse by blowing first so I ordered a new one, along with replacements for all the electrolytic capacitors in the power supply. This power supply clearly runs quite hot as indicated by discolouration on the PC board in various places, so it was possible that one or more electros had been adversely affected by heat. The module duly arrived but substituting it for the original made no difference. Next, I worked out the approximate values of load resistance to fit to each of the six output voltage rails and made a jury-rigged “dummy load” for the unit. I judged this to be necessary, because I wasn’t confident about running the supply unloaded. Having done that, I then decided to replace all the electrolytic capacitors in the power supply, not because I had any real suspicions about any one of them but because electrolytics are frequently responsible for faults. There are 16 of them on the board and one in particular proved to be troublesome. This was the main filter capacitor for the 340V rail which is derived by rectifying the mains. The original capacitors were all rated at 85°C but I made sure that all the replacements were 105°C types in view of how hot the unit normally runs. In addition, I decided to cool things down a bit by mounting a tiny fan in the power supply box and connecting it to the +12V rail. I figured that even a small airflow through the case would be better than virtually none at all. Having replaced the electros, I reapplied power and the power supply Australia’s Lowest Priced DSO! Now you’ve got no excuse ... update your old analogue scopes! Whether you’re a hobbyist, TAFE college or university workshop, the GW GDS-1022 has the price and performance for you. GW GDS-1022 25MHz 25MHz Bandwidth, 2 Ch 250MS/s Real Time Sampling 4k Memory Per Channel TFT Colour Display 19 Auto Measurements Built-in USB & SD Card Slot GW Brand - 28 years in Australia Sydney Melbourne Tel 02 9519 3933 Tel 03 9889 0427 Fax 02 9550 1378 Fax 03 9889 0715 email testinst<at>emona.com.au siliconchip.com.au Brisbane Tel 07 3275 2183 Fax 07 3275 2196 Adelaide Tel 08 8363 5733 Fax 08 83635799 Perth ONLY $ Tel 08 9361 4200 Fax 08 9361 4300 web www.emona.com.au 549 inc GST EMONA December 2008  43 Serviceman’s Log – continued came to life. All the rails were at their correct values much to my relief and I also now had a spare control module in case of future problems. Fairly obviously, one of the original electros was faulty. Power blanking unit Now that the switchmode supply was working again, I turned my attention to the Power Blanking Unit (PBU) to try to solve the focus problem. In order to work on this, the board had to be swung out from its position. In addition, in order to make scope measurements, I made up an extender cable to connect the PBU to the power supply. I could now make some more measurements on the focus voltage circuitry. Having probed around for a bit, I noticed that one of the high-voltage ceramic filter capacitors (C54) had a crack in its coating. This capacitor is a 1000pF 2kV device and it normally has about 1200V across it. When I poked the cracked coating, a large chunk of it fell away. This revealed some corrosion of the soldered connection to the metal coating on the ceramic disc. The capacitor was replaced with a 1000pF 3kV device and the focus voltage then came up to 44  Silicon Chip the full 1200V immediately on switch on, again much to my relief. To check the CRO out thoroughly, I next attached a probe and connected it to the calibration signal terminal on the lower front panel. With the timebase switched to Auto mode, the trace appeared but is was not being triggered so that the square wave calibration signal was not visible on the screen. Normally, you would adjust the trigger level to make the waveform stationary. However, when I did this, the trace disappeared altogether. Clearly another fault had developed. It looked as though the trace was being blanked as soon as it was being triggered. In order to test this theory, I borrowed another CRO and looked at the A-blanking signal which is generated on the Trig Sweep Unit (X74-1350-00), exiting the board on P28, pin 4. This showed that the trace was indeed being blanked. To confirm this, I looked at the +Sweep signal at P35, pin 4. This is the timebase ramp waveform which sweeps the spot across the screen at a uniform rate. However, the timebase waveform just wasn’t there. In other words, rather than the trace being blanked, it wasn’t being triggered at all, even though the trigger adjustment was correct. To backtrack a little, the Trig Sweep Unit is on a PC board measuring about 250 x 100mm. This includes the triggering and sweep circuitry for both the A and B timebases. There are 12 high-speed ECL logic ICs on the board, plus dozens of transistors and scores of minor components. The fault just had to be on this board somewhere. I counted 33 electrolytic capacitors and after my success with a bulk replacement of these in the power supply, I decided to do the same on the Trig Sweep Unit. Anyway, I replaced all 33 capacitors and then reconnected the multitude of plugs (20 or thereabouts) to the board. I then powered it up and found that the fault was still there which was frustrating but not really surprising. Still, I had eliminated one potential source of problems. Triggering for the A timebase comes from the A Trig Switch Unit and enters the timebase board via P46. Unfor- tunately, the pulses on P46 were too narrow to be visible on the borrowed CRO which had a bandwidth of just 20MHz. However, following IC1a and IC1b which constitute a Schmitt trigger, the widened pulses were visible as long as the trigger level was adjusted. IC2a is a bistable flipflop which has two modes of operation. The first is the Reset-Set (R-S) mode and the second the JK or clocked mode. The important thing I noticed here was that when the trigger pulses were present, the flipflop wasn’t clocking and so the sweep wouldn’t start. So it seemed that the IC was faulty. Fortunately, the circuits for this part of the two timebase circuits are identical and I could compare them, rather like the two channels of a stereo audio amplifier. There was another MC10H131 on the PC board, so I swapped it over. When I did that, the A timebase then worked, producing a nicely triggered waveform. A replacement IC then got the B timebase working again. Flickering trace There was just one final fault to fix. When the scope was switched on from cold, an out-of-focus trace resulted which flickered for a time before settling down. To fix this, I initially replaced two more high-voltage ceramic capacitors (C38 & C39) on the Power Blanking Unit board and this appeared to do the trick but the problem was back the next day. It was then that I noticed a tiny spark on the PC board which was generated in time with the trace flicker. This spark was caused by tracking of the -1200V across the surface where a rubber support for two neon lamps had perished. In fact, there were two of these pairs of neons and both supports had perished. I removed the neons, scraped away the remains of the supports and cleaned up the board as best I could. A coat of clear varnish over the damaged area gave some assurance that it wouldn’t happen again. At the next switch-on, the trace came up in focus and there was no flicker. So the old CRO was restored to full working order, although I have to admit that the diagnosis and repair of the various faults was spread out over about a year. I guess servicemen in business don’t SC have that luxury. siliconchip.com.au Christmas Wishlist DON’T FORGET YOUR HOLIDAYS WITH THIS HANDY DIGITAL VIDEO CAMCORDER SOLAR POWERED DIGITAL MULTIMETER If you want to shoot a few “You Tube” videos or clips of the kids, this one will do the job. It has a quality CMOS sensor, 16MB internal memory or just add an SD memory card to the provided slot and save directly to it. You can also use it as a 5.0MP still camera. An environmentally friendly DMM with rechargeable batteries that can be charged from the built-in solar panel, 12-36VDC or from mains power. 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Practical for gamers, students etc. Besides the practical aspect, it looks cool. • Red or Blue user selectable illumination • USB powered • Adjustable brightness • Palm rest • Plug & play • Media hot key • Size: 473(W) x 195(H) x 11(D) mm 54 95 Cat: XC-5149 Spare Receiver also available for AR-1839 $54.95 Cat: BM-2442 $ All I Want for Christmas is at ESD SAFE LEAD-FREE SOLDERING STATION $ 165 Cat: TS-1390 Designed for both lead-free and ordinary leaded solder, the iron has a wide temperature range which is microprocessor controlled and maintained to within a few degrees of the selected setting. The soldering pencil is fitted with a soft insulated rubber grip and has a silicon rubber sheathed power cable. The control unit houses the temperature controls and simultaneously displays the set operating temperature and actual tip temperature, as well as system status on its digital LCD panel. • High powered 80W heater • Easy temperature setting • 1°C temperature increments • Fahrenheit or Celsius temperature display • Variable tip temperature 160°C to 480°C • Mains powered • Low voltage (24V) iron • Control unit 125(W) x 180(H) x 240(D)mm Spare conical tips available separately. Look for our NEW ESD SAFE LEAD-FREE Due mid December '08 DESOLDER STATION on page 4 City Store 221 Morphett St Adelaide 5000 Ph: (08) 8231 7355 We have moved! New location with off street parking for ADELAIDE, SA DVR CAMERA SURVEILLANCE KIT This is an excellent DVR that is ideally suited to smaller surveillance installations around the home or office. It uses MJPEG video compression and can store over 150 hours of video on its 250GB hard drive. Recording setup is simple and various trigger modes can be set across the day including timer recording, motion detection & manual operation. Supplied with 4 x weatherproof colour night vision cameras, connecting leads and wireless remote. • 1 x composite video output • Frame rate 25fps (Quad mode) • For full specifications log on to our website * Note: Monitor not included. $ 649 SCREEN SHOTS Cat: QV-3063 PH: (08) 8231 7355 Free Call: 1800 022 888 for orders! 1 Party Time 2.4GHz AV Sender/Receiver Send your audio and video all over the house wirelessly on the 2.4GHz band. Use your cable TV, CD, DVD remote to change channels, volume and settings from the receiver end of this 2.4GHz system. Send stereo audio and video pictures around your home, shop or office, allowing you to watch video $ 95 or listen to hi-fi quality stereo sound anywhere. Send surveillance camera images Cat: AR-1836 to another part of the building. All without the need to run cables. Features a phase-locked loop (PLL) electronic circuit that constantly adjusts, locking onto any input signal and avoiding any reception drift. Spare Receiver also available AR-1837 $44.95 Simple but effective! Coloured lights switch in time with the music. Supplied with a red, yellow, green, and blue globe ES 240V reflector globes. 76 $ • 435mm wide • Spare globes available - ask in-store 76 95 Cat: SL-2942 Disco Party Set Avoid the congestion and interference on the crowded 2.4GHz band & enjoy reliability and assured picture quality with this 5.8GHz AV sender. $ 155 Cat: CS-2516 2 x 100 WRMS Stereo Amplifier with Remote Control $ 76 95 Cat: SL-2978 $51 Green Laser Light Show This is a good looking, no-nonsense stereo amplifier that is rated at a generous 100 watts RMS per channel and will form the heart of an impressive stereo system. This truly is a portable take anywhere laser light show that will liven up any party. $ Extra 5.8GHz receivers sold separately AR-1841 $99 148 Cat: AR-1840 • Operates the FOXTEL and Austar Digital Set Top Boxes • 2 x AA batteries included $ Cat: AR-1735 Can’t decide what to get for that “hard-to-buy-for” friend? What about a Jaycar Gift Voucher? With over 6,500 products to choose from they’ll be sure to find something useful! 89 95 Cat: AF-1214 Plasma/LCD TV Wall Bracket - 45kg Heavy Duty Plasma/LCD Wall Brackets Capable of taking up to 80kg, these heavy-duty LCD or plasma TV brackets will save valuable floor space and keep your investment out of reach of mischievous fingers. Two types are available: $ 95 • CW-2822 has a 30° range of tilt movement only Cat: CW-2822 • CW-2824 is able to tilt 30° & swivel left & right through 80° and extend up to 30cm away from the wall. $ This is the baby model, designed for LCD TVs from 23-37" in size and weighing up to 45kg. Despite the low price, it's still solidly made and features a security locking bar. It can be mounted flat or at a fixed tilt angle of 5°, whilst the TV is only spaced 38mm from the wall. • VESA standard compliant • Solid steel construction • Mounting hardware and instructions included $ $ 219 Cat: AA-0470 18 Watt RMS Stereo PA Amplifier Cat: SL-2937 • 70 cubic metres/min fog output • 800ml fog juice capacity • Measures: 330(L) x 160(W) x 140(H)mm • Spare Fog Juice 1 litre AF-1212 $12.95 21 95 Note: Actual stock may vary from photo shown 189 Produces clouds of white fog on demand. Fantastic for use with laser light shows, mirror balls & other party lighting. Mains powered. Designed specifically to operate your Pay TV Digital Set Top Box and give you direct access to the special features available on the name brand remote. Approx 180mm long. ® $ Rave Fog Machine Pay TV Set-Top-Box Remote Control $ • Inputs for Mic, Tape, Tuner, AV1, AV2, CD, Phono • Approx 420mm wide • 100 pre-set geometric patterns • Auto, music, manual and speed control settings • Mounting bracket included • 240VAC adaptor included • Approx 200mm long NOW WORKS WITH DIGITAL PAY TV REMOTES 64 95 Cat: CW-2826 165 This simple, low cost 18W per channel transistor amp is surprisingly loud! It is protected from accidental speaker wiring shorts and, if abused will simply shut down and reset after it has cooled off. It has a front panel microphone input, bass and treble controls as well as a master volume control. $ • See our website or catalogue for full specifications. 43 95 Cat: AA-0472 AV HDMI Lead Type A plug to Type C or 'Mini' HDMI socket cable. For connection to portable HDMI devices. • 3 metres length. • Gold plated internal shield • 24K gold contacts • Internal dual strain relief • Triple shielded • Nitrogen gas injected dielectric • RoHS compliant • HDMI v1.3 compliant $ 54 95 Cat: WQ-7412 Right Angle HDMI Adaptors Cat: CW-2824 Adapts HDMI plug to socket at right angles. Perfect for wall mounted TV applications. Gold plated connections. Two types available: 99 2 Rated at 300 watts RMS this wide range speaker is ideally suited for use as a foldback speaker on stage or as reinforcement in an existing system. The box features an eightohm, 12" sub-woofer for rumbling bass and a horn tweeter to give crisp, clear mid range and high frequencies. • Frequency Response: 40Hz to 18kHz • Box Size: 650(W) x 330(H) x 440(D)mm Liven up your next party with this professional lighting set. The kit includes a 20cm (8') mirror ball with a 240VAC motor, 240V pin spot light and stand, PAR 36 bulb and 4 coloured filters in red, amber, green and blue. 5.8GHz AV Sender • Range of up to 50 metres (line of sight) • Built-in IR remote functionality • No messy wires Was $199 12” Full Range Speaker 4 Colour Light Chaser Sound Modulated Note: TV not included Right Angle Down Cat. PA-3646 Right Angle Up Cat. PA-3648 $ 10 95 Cat: PA-3646 $ 10 95 Cat: PA-3648 Free Call: 1800 022 888 for orders! www.jaycar.com.au At Jaycar UPGRADE YOUR CAR AUDIO THIS SUMMER! Rack Mount Dual MP3 Controller The convenience of MP3 with the flexibility of full pitch, cue and track controls will add seamless flexibility to your DJ or home studio setup. It accepts two SD cards up to 4GB capacity and gives a huge array of control over every track on each card. The backlit LCDs indicate all functions as they happen. • Supports ID3 Tag • 19’’ 2U standard size • Power source: 6VDC 1.5A • Output: 2V ±0.5dB • Frequency response: 17Hz - 16kHz • Dimensions: 483(W) x 88(H) x 78(D)mm Car Speakers $ 438 Cat: AA-0492 Portable Combo 30W PA Amp with USB This busker's amp has a USB port as well as the normal mic/audio inputs, so you can plug in a memory stick and play backing or rhythm tracks in your performance. In addition, you can connect an MP3 player or CD player to the line level inputs via the RCA sockets. It has a built-in rechargeable battery that gives you 3-5 hours of use or it can be mains powered. 5" 2 Way • Power handling 70WRMS • Freq resp 80Hz -20kHz Cat. CS-2386 $44.95 pr 200 WRMS 12" Party Speaker This speaker can handle a massive 200 WRMS and is an excellent addition to any entertainment equipment range. It provides good performance in difficult locations such as backyards, tents, party rooms or halls etc. 6" 3 Way • Power handling 85WRMS • Freq resp 65Hz - 20kHz Cat. CS-2387 $54.95 pr 6 x 9" 4 Way • Power handling 100WRMS • Freq resp 45Hz -20kHz Cat. CS-2388 $64.95 pr • Size approx 650(H) x 370(W) x 450(D)mm. • Separate volume control on USB channel • Mic input • Battery or mains powered • 3 channel mixer • Dimensions: 245(W) x 280(H) x 245(D) $ 275 Cat: CS-2519 $ Low Profile Subwoofer Their huge power handling and cone excursion make these the ideal subs for people who really want massive SPL in a compact package. Two models available. Nominal impedance 4 ohms 10" 250WRMS Cat. CS-2356 $89.95 ea 229 Cat: CS-2514 i-Mix Club USB DJ MIDI Controller Mix, play and scratch your own MP3 tracks directly from your PC. The i-Mix gives you the control you lose when going from a traditional mixer to a laptop. It sends MIDI data from the controller to your DJ software without the inconvenience of mouse control. Complete with LE versions of Deckadance and Traktor 3 software. This is the ultimate tool for the performing DJ. • 2-deck controller • Mix 2 files in 1 controller • USB powered, no extra power needed • Totally portable, smaller and lighter than a laptop • 2 pro jog wheels • Pitch, search and scratch • 3 faders: 1 cross fade, 1 volume per deck • 6 EQ filters with 6 kills Home Theatre Powerboard • Mains adaptor included. • Supports up to 1080p resolution • 12VDC 500mA power supply • Dimensions: 190(W) x 90(H) x 23(D)mm 3 Way Audio Selector $ 109 Cat: AC-1648 Many audio amplifiers don't provide enough inputs for all your components. Takes up to three stereo RCA inputs and provides a single stereo RCA output. • 3 pairs of RCA inputs • Dimensions: 133(W) x 42(H) x 85(D)mm $ Surge protection and filtering is provided to all your home theatre equipment connected to this powerboard as well as current protection via the inbuilt circuit breaker. • Provides protection to telephone, data via a network connection, satellite/cable TV and TV aerials 15 95 Cat: AC-1655 From $ 89 95 This excellent Great Audio unit will play Deals In-store! DVDs, VCDs, MP3s, CDs, and AM/FM radio. The built-in 3" TFT screen doubles as a control panel when listening to MP3s etc. It also has an auxiliary audio input for external MP3 or tape player etc. The player fits a standard DIN slot and has a detachable face and can be operated by the included remote. 399 This AV distribution amp allows you to take advantage of HDTV on digital pay-TV and free-to-air. 12" 350WRMS Cat. CS-2358 $109 ea In-Dash Multimedia Player $ System requirements: Windows XP SP2 or Vista Cat: AM-4250 Pentium III or Athlon 1GHz 512MB RAM Dimensions: 360(W) x 202(H) x 45(D)mm 4 Way AV Component Distribution Amplifier This new improved range of full range car speakers feature injection moulded woofer cones and silk dome tweeters for smooth high-end response. The 3-way models have piezo mid-range drivers and all have grilles and crossovers included at a price that won't break the bank. See in-store or website for speaker measurements and specifications. 4" 2 Way • Power handling 55WRMS • Freq resp 100Hz - 20kHz Cat. CS-2385 $34.95 pr $ 64 95 Cat: MS-4024 Curly Musical Instrument Lead $ 9 95 Cat: WA-7026 6.5 - 6.5mm mono plug to plug curly cord instrument lead. Suitable for all musical instrument applications. Extends to 6 metres. • Mounting hardware included. • Resolution 500TV lines • 2 x video inputs / 1 x camera input • 45W RMS per channel • Frequency response: 20Hz - 20kHz $ 385 Cat: QM-3787 HID Spotlight Conversion Kit This is a simple single version of a High Intensity Discharge (HID) headlamp that you are now seeing on up market cars. It is one lamp set only. Could be used to convert some spotlights to a much more powerful and effective spotlight. The kit includes a $ 95 35W Xenon HID lamp, 6000°K, with H4 base, ballast unit and wiring harness. Cat: SL-3368 It is a very simple installation. 99 • Light output approximately 3000 lumens at 12V. Free Call: 1800 022 888 for orders! www.jaycar.com.au 3 GREEN POWER - ALTERNATIVE ENERGY PRODUCTS ABS IP65 Instrument Cases These are excellent cases and you will be hard pressed to find a better product anywhere near the price. Ideal to protect photographic gear, test/measurement equipment, scientific/medical equipment etc. from transit damage, dust and water ingress. Powertech Monocrystalline Solar Panels These monocrystalline panels are more efficient than polycrystalline panels and are as strong and tough as the better known brands, but at a more attractive price. Sizes range from 5 watts to a massive 175 watts. • Each has a soft pluck foam insert with pre-cut squares that can be removed to snugly fit the item you want to protect. • The lids are also lined with egg shell foam, and are secured with strong snap closed fasteners with a gasket seal that is waterproof and dustproof to IP65. Three new sizes all with 2 year warranty: Note: camera equipment not included • Internal: 310(W) x 190(H) x 112(D)mm • External: 330(W) x 210(H) x 120(D)mm Cat. HB-6382 $ $ Wind Generators 5W 10W 20W 65W 80W 120W 175W Cat. ZM-9091 Cat. ZM-9093 Cat. ZM-9094 Cat. ZM-9096 Cat. ZM-9097 Cat. ZM-9098 Cat. ZM-9099 $115 $175 $279 $639 $875 $1,280 $1,750 89 95 Cat: HB-6382 129 Cat: HB-6384 • Internal: 359(W) x 239(H) x 152(D)mm • External: 380(W) x 260(H) x 160(D)mm Cat. HB-6384 $ • Internal: 399(W) x 279(H) x 110(D)mm • External: 420(W) x 300(H) x 120(D)mm Cat. HB-6386 Note: Stock will be black. Note: Pictures may vary from models shown 145 Cat: HB-6386 This excellent desolder station has been built to accommodate the wide temperature range required for lead-fee solder and is ideal as a general purpose, or specialised lead-free desoldering applications. Protect your valuable solar installation and maximise battery service life with our photovoltaic (PV) charge controller. Microprocessor controlled with LCD, this charger efficiently charges a vast selection of batteries from a wide range of solar panels. It even features an equalisation mode for wet type lead-acid batteries, and automatically cycles once a month for 2 hours. 679 679 Cat: MG-4532 Cat: MG-4530 • Set of 3 Spare Blades (Cat. MG-4534) $76.95 New to the SLA Battery Range $ 155 Cat: MP-3129 Used for connecting the output of two solar panels in parallel or connecting multiple panels in an array. Waterproof and UV resistant. Generally used on the negative pole of the panel. 2 Sockets to 1 Plug Here are three new additions to the already extensive Jaycar range of sealed lead-acid batteries. All are 12V, 6Ah is used for back up power for alarms systems while the 9 & 12Ah units are commonly used for high drain applications such UPS and electric vehicle, wheelchairs, small motor bikes etc. $ 95 12V 6Ah SB-2485 Cat: SB-2487 12V 9Ah SB-2487 12V 12Ah SB-2489 39 1 Plug to 2 Sockets $ $ 27 95 Cat: PS-5110 • 80 watt ceramic element • 130W heater boost mode • Vacuum pressure 600mm Hg • Fahrenheit or Celsius temperature display • Microprocessor controlled $ • Temperature range 160°C to 480°C • Set and actual temperature display • Spare tip available • Due mid December '08 219 Cat: TS-1386 50W 240V Temperature Controlled Soldering Iron $ 27 95 Cat: PS-5112 27 95 Cat: TS-1540 Cat: SB-2485 $ 54 95 Cat: SB-2489 Ultra-Low Distortion 135WRMS Amplifier Module Kit This excellent keyless entry system features two independent door strike outputs and will recognise up to 16 separate key fobs. Supplied with solder masked and silk screen printed PCB, two programmed micros, battery and all electronic components. The receiver requires a 12VDC .5A power supply. $ Some SMD soldering is required. This ultra low distortion amplifier module uses the new ThermalTrak power transistors and is largely based on the high-performance Class-A amplifier. Kit supplied with PCB and all electronic components. Heat sink and power supply not included. Refer Silicon Chip Magazine Oct. 2007 49 95 Low Cost Programmable Interval Timer Kit $ 27 95 Rolling Code Infrared Keyless Entry System Kit Cat: KC-5458 If your budget doesn't extend to a soldering station, you can still have temperature control. This iron is adjustable with a dial on the handle. It has a temperature range of 200 - 450°C, high enough for silver soldering if needed. Plated long-life tip. 4 $ • Pin dimension 4mm • 300mm • Tin plated copper contacts Look for our NEW ESD SAFE LEAD-FREE SOLDERING STATION on page 1 • Spare tip available • Due mid December '08 300W 24VDC $ 300W 12VDC 20A Solar Charge Controller Solar Panel 'Y' Leads ESD Safe Lead-Free Desolder Station The new super-compact 300W units are a technological step up from our other two models.They feature moulded, compact, efficient blade design, are lightweight, have neodymium magnets, and the charge controller is built into the generator head. They also feature slip rings to avoid cable breakage. These 300W units will start spinning at just 2.5m/s wind speed, and will produce their rated power at 12m/s (max *No mounting power 500W at 15m/s). hardware, Available in 12V and 24V poles or guide outputs, all parts fit into one wires included. box weighing just 17kg making it convenient to UP to transport. 500W Peak • Rated Power: 300W • Max Power: 500W • No of Blades: 3 • Blade Material: ABS • Included: generator, blades, tail, hub, nose cone Ref: Silicon Chip Magazine June 2008 $ 29 95 Cat: KC-5464 Here's a new and completely updated version of the very popular low cost 12VDC electronic timer. It is link programmed for either a single ON, or continuous ON/OFF cycling for up to 48 on/off time periods. Kit includes PCB and all specified electronic components. Ref Silicon Chip Aug. 2008 • Output Power: 135WRMS into 8ohms and 200WRMS into 4ohms • Frequency Response at 1W: 4Hz to 50kHz • Harmonic Distortion: <.008% from 20Hz to 20kHz $ 89 95 Cat: KC-5470 Power Supply Kit for Ultra-LD Mk2 200W Amplifier Kit Ref Silicon Chip Sept. 2008 This power supply kit is specifically designed to provide a balanced +/55VDC supply to power this fantastic amp kit. $ 95 • Kit includes PCB & all electronic components. Cat: KC-5471 54 Free Call: 1800 022 888 for orders! www.jaycar.com.au GREAT GIFT IDEAS FOR THE OUTDOORS 1000 Lumens Luxeon® Torch The Amazing Flygun Powered by 7 Luxeon® Rebel LEDs, this powerful torch is the new benchmark for the industry, rivalling the brightness of HID. 1000 lumen output is around the equivalent of a 60 watt light bulb, so is ideal for security and rescue personnel. It's housed in an extremely durable O-ring sealed, machined aluminium body finished in gun-metal grey. • Focusing beam: 1x - 4x • Burn time: Low - 9.5 hrs, High - 4 hrs • Weight: 1690g with batteries • Dimensions: 435(L) x 40(Dia)mm $ Get rid of flies and other insect pests and have some fun at the same time. The kids will love it and so will you. • Suitable for 8yrs+ $ 189 A combined multiplexer and digital video recorder with Ethernet port, which allows control via a web browser. Features MPEG-4 compression, advanced motion recording, covert recording, video loss detection, remote network record and back-up support. Supplied with a 250GB HD and can be expanded up to 400GB. See website for specifications. 7 95 Rechargeable 35W HID Spotlight If you need serious light power, HID is the only way to go. Compared with quartz-halogen, HID has far longer bulb life, uses less energy and is much brighter. With a pounding 3300 lumens, this spotlight is ideally suited to search and rescue, boating, professional shooters, security or other highpower applications. It's housed in a tough weather-resistant ABS housing and has a handy shoulder strap for extended use. The built-in rechargeable battery gives about 50 minutes of continuous use and it recharges either from the mains plugpack or a car cigarette lighter socket provided. $ 165 • 1/4" Sony CCD • 330 TV Lines • 120mm long • Submersible to 1 metre Modified Sine Wave Inverters Power Voltage Price 12VDC to 230VAC 12VDC to 230VAC 12VDC to 230VAC 12VDC to 230VAC $54.95 $84.95 $155.00 $249.00 A fantastic communicator for the discerning user. Built-in scrambling prevents eaves dropping and 500mW power gives up to 5km range. Great for family picnic and road trips etc. Includes recharging base that charger two transceivers simultaneously • Crystal Clear FM system • Includes one handset & dual charging cradle • Repeater function • No licence required • Spare transceiver available $ 95 separately DC-1028 59 Cat: DC-1025 1.5W 38 Channel UHF CB Radio A versatile transceiver with a maximum output of 1.5W and a 500mW power saving mode. All 38 legal channels are utilised as well as CTCSS sub channel calling, automatic squelch, and four level scrambling for private communications. Other features include dual-watch, VOX, and a built-in stop watch. $ DC-1028 Extra handset Was $49.95 Now $39.95 Save $10 These two mains surge protectors alleviate the majority of problems caused by these increases in voltage, which damage delicate and expensive appliances connected to your power outlets. Each model has three-way protection across active-neutral, active-earth and neutral-earth and is fully approved for electrical safety. Two models available: Double Power Outlet Protection Cat. MS-4015 Single Power Outlet Protection and Phone Protection Cat. MS-4017 $ 10 95 Cat: MS-4015 $ 16 95 Cat: MS-4017 219 Cat: QC-3492 This tiny camera is excellent value for money and has specifications comparable to some higher priced dome cameras. 38 Channel UHF Pocket CB Radio Mains Surge Protectors $ Low Cost Colour Mini Dome Camera - Sharp Sensor Take your creature comforts with you when you go bush or on any road trip as these inverters will produce mains power from your vehicle's battery. A 150W inverter will run some laptops, lights, small TVs and recharge batteries. Inverters 300W and above will also run power tools, fluorescents & larger style TVs. 150W 300W 400W 600W Cat: QV-3079 This camera is rated to IP57 making it suitable for exposed outdoor locations. It features infrared LEDs for night vision and an integrated sun/rain shield. Mains Power On The Go! MI-5102 MI-5104 MI-5106 MI-5108 599 IP67 Day/Night Colour Pro CCD Camera Cat: ST-3369 Cat. $ • 340mm wide • MPEG-4 compression • 250GB HDD included Cat: YS-5545 Cat: ST-3371 • Battery: 12V 7AH rechargeable lead acid • Mains adaptor: 15VDC 500mA • Dimensions: 300(L) x 210(Dia)mm Economy 4 Channel Multiplexing DVR 99 95 Cat: DC-1045 Retractable Car Charger for iPod® • Sensor: 1/4" • Sharp CCD • Sensor resolution: 350 • Horizontal TV lines • Min illumination: 1 lux • Lens: 3.6mm (92°) • 72(dia) x 52(H)mm $ 74 95 Cat: QC-3291 Microphone/Amp for CCTV Cameras Easy add-on mini microphone with built-in amp for cameras that require an audio function. Simple to install and ideal for all surveillance applications. • High sensitivity microphone (-65dB) • 12VDC operation • Length: Approx 50cm $ 21 95 Cat: QC-3434 This sleek, attractive car charger is suitable for all versions of iPhone®, including the latest iPhone® 3G, and will also charge all the different iPod® versions. Fitted with a curly cord, it will easily fit in your glove box without making a tangled mess of wires. Finished in gloss black. Clip-On CCD Reversing Camera Specifications: Input: 12-24VDC Output: 5VDC, 500mA • 3M double-sided tape included • 7 metre cable included • Sensor: 1/4-inch colour CCD • Resolution: 380 TV lines • Supply voltage: DC 5 to 15V, 75mA • Viewing angle (diagonal): 150° • Camera size: 25 x 25mm $ 19 95 Cat: MB-3654 Compact reversing camera with a variety of mounting options: number plate holder, flush or surface mounted, with screws or with double-sided tape (included). It also includes a bracket for mounting to roof racks on commercial vehicles. Free Call: 1800 022 888 for orders! www.jaycar.com.au $ 275 Cat: QC-3729 5 Great Christmas DON’T FORGET BATTERIES FOR CHRISTMAS Alkaline batteries for every occasion. Cat RRP Pack Size 24 AAA SB-2331 $14.30 24 AA SB-2330 $14.30 40 AA SB-2332 $21.95 4 C SB-2320 $7.70 4 D SB-2321 $9.00 6 9V SB-2417 $15.25 From $ 7.70 4-in-1 Retro Music Centre with USB/SD Record to SD card or via USB with this retro all-in-one music centre. It does everything: AM/FM radio, turntable, cassette player and CD player. You can save tracks to an SD card or to a PC as WAV or MP3 files. • LED display • CD/CD-R/CD-RW discs compatible • 33, 45, 78 RPM automatic turntable • Power consumption:13W • Dimensions: 465(W) x 225(H) x 345(D)mm Due 10th Dec 08 $ 299 Cat: GE-4058 World Band AM/FM/SW PLL Radio Receiver This is a great radio and its list of features will amaze you. It uses a phase-locked loop (PLL) for rock solid frequency stability and has an AM band, FM band (stereo), and three short-wave bands covering 1711kHz to 29999kHz. See website for full details. Fast 30 Minute Charger Recharge one, two, three, or four AA or AAA Ni-MH batteries with this handy charger. It uses Delta V voltage detection for optimum charging and long battery life. Includes mains plugpack and car adaptor. $ • Charge time depends on battery capacity 54 95 Cat: MB-3547 • Size: 290(W) x 185(H) x 70(D)mm • Requires 4 x D batteries $ 109 Cat: AR-1747 Battery Charger with LCD Recharge up to 4pcs of AA or AAA Ni-Cd or Ni-MH batteries with this handy charger. With Delta V voltage detection, the batteries are charged to their optimal level. Charge state can be monitored on the integrated LCD which is backlit. Includes 240V plug pack and car charging cable. Computer Connect Weather Station with Wireless Sensors $ 54 95 Cat: MB-3543 Powertech Rechargeable Batteries • Packs of 4 Ni-MH rechargeable batteries. SB-1739 900mAh AAA $15.90 SB-1737 2000mAh AA $14.95 From SB-1738 2500mAh AA $21.50 $ The outdoor sensors will transmit up to 60 metres to the receiver, which has full clock and calendar functions and shows wind direction, chill factor and speed. Also shows barometric pressure with 24 hour trend, rainfall, indoor and outdoor temperatures and other weather data. Connects to your computer for data storage and analysis. Easy to install - no fuss, no wires. The indoor receiver has a large LCD which shows full clock & calendar functions, humidity, temperature readings, barometric changes as well as an audio and visual annunciation when the doorbell is pressed. It can also be either desk (stand supplied) or wall mounted. • Indoor display 225(W) x 260(H) x 27(D)mm • Requires 2 X AAA & 2 x CR2032 batteries Was $99.95 $ $30 69 95 Cat: XC-0336 Infrared Wireless Stereo Headphones A great pair of headphones at a fantastic price! Setup is quick and easy and the sound clarity is excellent. The ultra-light design allows them to comfortably sit on your head and you’ll hardly know they're there. • Mast length 500mm. • Operation distance: up to 15m • Requires 2 x AA batteries 15 90 $ Wireless Weather Station with Doorbell $ 199 54 95 Cat: AA-2049 Cat: XC-0330 UNINTERRUPTABLE POWER SUPPLIES FOUR PACK SAVINGS Pre-Charged Rechargeable Batteries These fantastic batteries feature ultra-low self-discharge technology and have an 85% charge retention after 1 year. They are supplied in a charged state and can be used immediately after purchase. A handy storage case is included. 6 Protect your valuable computer system and critical data from black-outs, brown-outs, and power surges. Battery back time is 10 minutes which lets you power-down without loss of data! The UPS is supplied with back up batteries, USB interface cable, and software. See our website for full specifications. Two models available: 650VA $129 Cat. MP-5200 • AA & AAA styles are available SB-1752 AAA 800mAh - Pk 4 SB-1750 AA 2000mAh - Pk 4 Stand-by UPS Systems $16.50 $27.50 1000VA $219 Cat. MP-5202 $ 129 Cat: MP-5200 Line Interactive UPS Guard your computer and peripherals from the shortfalls of mains power. These Line Interactive UPS units protect against low/over voltage, surges, short circuits and power overloads. The battery power, load, input/output voltage is display on an easy to read orange backlit LCD. • 3 mains sockets • Microprocessor control for high reliability • With AVR • RJ45 protection • 10-30 minute back up time Two models available: 650VA $165 Cat. MP-5204 1000VA $349 Cat. MP-5206 $ 165 Cat: MP-5204 Free Call: 1800 022 888 for orders! www.jaycar.com.au Gift Ideas Hands-Free Bluetooth FM Transmitter Plug in your iPod® or iPhone® and listen to music through your car's FM radio. If you get a call, you use the phone handsfree without losing the music. Kid Safe Keep your valuables secure in your own electronic safe. Includes coin slot and effects. • Each requires 3 x AA batteries $ 95 • 185(H) x 135(W) x 125(D)mm Advanced Digital Distance Calculator 16 $ • USB port • 3.5mm input jack for audio auxiliary input • Gooseneck: 200mm long • Size: 140(H) x 75(W)mm Converts map scale to real distance! The device works in miles, kilometres, and nautical miles! Includes a small torch for use in the dark. Cat: GH-1310 16 95 Cat: GH-1311 Note: iPod® not included • Requires 2 x AAA batteries $ • Invigorating ice cool • Relieving Hot Stone • Oscillating vibro-therapy • 370mm long $ • Charger included Enabling the addition of up to six extra displays, this adaptor allows you to add high-resolution graphics without having to add a graphics card - just connect it to any USB 2.0 port. Two Speed Desk Fan Keep yourself cool this summer. This tilt adjustable fan has two operating speeds and is ideal for use at work or home. • Totally portable • Battery powered • Measures 130(W) x 160(D) x 75(H)mm 59 95 Cat: AR-1868 USB to DVI Adaptor *ATM model also available The Revibe cordless massager provides 3 unique spa therapy programs in one incredible handheld machine. 109 29 95 Cat: XC-0377 Rechargeable 3 in 1 Massager $ $ 10 95 Cat: GH-1074 Cat: GH-1758 • Video output with DVI connecter • Supports VGA/HDMI video output via DVI-VGA/DVI-HDMI adaptor • Resolution: up to 1,600 x 1,200 pixels at 32-bit colours • No external power supply needed $ • Supports Vista Aero 165 Cat: XC-4879 Analogue Projection Clock With a classic Roman numeral display and a fully animated sweep second hand, your LED Projection Clock will really stand out. The clock movement is powered by an AA battery and the projector runs from the mains adaptor (included). Perfect for the kids' room, entrances, lobbies, reception rooms or waiting rooms. Table or ceiling mount. • 40,000 hours LED life • Requires 1 x AA battery • Mains adaptor included • Low power consumption • Measures: 230(L) x 135(Dia)mm $ USB RJ45 Extension Adaptor 74 95 Cat: XC-0217 Radio Controlled Mini Monster Trucks These little beasts have enormous wheels for getting over obstacles and working rear suspension for maximum traction. You can wheelstand them or just put the hammer down and run over things. The truck charges from the remote control to give about 10 minutes of rootin' tootin' redneck truckin' fun. Two models to choose from so you can race them against each other: Green - 27MHz Red - 40MHz $ GT-3254 GT-3256 29 95 Connect any USB device to your computer from up to 50 metres away via a standard Cat 5 network cable. Now you can have your printer, webcam, keyboard, mouse or any other USB device exactly where you want it without having to move your computer around. • PC and Mac compatible • Uses standard Cat 5 cables • Supports USB 1.1 • Supplied with transmitter & receiver 64 95 $ Cat: XC-4884 Cat: GT-3256 USB DVD Maker • Remote Control included • Requires 4 x AA batteries (Use SB-2425) • Measures: 98(L) x 65(H)mm • Recommended for ages 8+ $ 95 • Sold separately 29 Cat: GT-3254 Retractable USB to Mini USB Lead 5 Port 100/1000 N-Way Gigabit Switch A high performance switch that offers a costeffective means of increasing network performance and reducing congestion. This is achieved by managing the transmission of data packets on the network and enables simultaneous connections to be made between several machines without interfering with data being exchanged on the other connections. 9 VAC power pack included. • Standards compliance: IEEE 802.3, IEEE 802.3u, & IEEE 802.3ab • Size: 130(W) x 103(D) x 27(H)mm 89 95 $ Cat: YN-8089 Retractable USB to Mini USB Lead. Keeps your work area neat and tidy. Suitable for cameras, GPS units etc and ideal for travellers or students. • USB 2.0 compliant • Extends to 800mm $ 10 95 Cat: WC-7712 Retractable Cat 5 Cable Suitable for LAN, Ethernet or modem connection. Retracts to store away easily and reduce clutter in your workspace. Particularly handy for business travellers. $ • Extends to 1.5m. Turn your VHS video tapes into exciting video productions or record live video straight to your DVD or CD burner. Editing software lets you add effects as well as sound tracks and titles to your work. $20 $ • Requires PC with suitable burner. Was $99 79 Cat: XC-4809 Adaptor for Nokia® Mobile Phones If you have a later model Nokia ® phone, you can use this adaptor to convert your charger outlet from the older Nokia® connector to the new smaller type. 5 95 $ 5 95 Cat: PA-3710 Cat: YN-8209 Free Call: 1800 022 888 for orders! www.jaycar.com.au 7 A nifty device to quickly indicate the condition of your 12V battery, charger or alternator. Uses three LEDs to indicate battery condition. Wireless Weather Station Features a large LCD with clock and calendar functions, dual in/out temp. readings, humidity, barometric pressure & weather trend. Includes one external transmitter. Was $49.95 • Measures 160(L) x 39(W)mm • Pink & White GH-1894 • Silver & White GH-1895 $ 16 95 $ EACH 39 95 Cat: XC-0335 $ Low Cost DMM 10 95 This full featured digital multimeter is perfect for the home handyman or young experimenter and will give years of reliable service. It features a huge 10A DC current range as well as diode and transistor testing functions. Also measures AC & DC volts and resistance. At this price you should buy two! $ $10 $ 39 95 Cat: AR-3114 This is our smallest ready-to-fly infrared remote control Mini Helicopter. It is made of durable plastic and is ideal for indoor use. • 20 minutes charge time for 8 minute flying time • Requires 6 x AA batteries • Helicopter 135mm long • Suitable for 8yrs+ 8 95 Cat: QM-1500 $ S 0 FT 10 GI R $ E OV This Christmas dust off those old LPs. This player includes a turntable, AM/FM stereo radio, cassette deck and a programmable CD player all encased in a cherry wood finish cabinet with two front stereo speakers. See our website for specifications. • 12" LPs & 7" EPs with 3 speeds 33/45/78 • Measures 390(L) x 360(D) x 260(H)mm • Ask how to back up your LPs to CD digital format. The turntable plays singles, EPs, albums and even your old 78s. $ $ 99 95 $ Twin rotors with buckets of power, 3 channel radio control unit with throttle, rudder and trim controls. Finished in matt olive livery with twin rocket pods. • Around 20 minutes flying time per charge • Requires 8 x AA batteries • Suitable for ages 10+ 8 6021 9699 9709 9678 9369 9905 4620 4365 9439 9476 9821 4965 4721 8832 9267 6788 4699 2822 9669 3899 4130 7155 3433 4799 6221 3100 3799 8337 3121 1614 Taren Point Tweed Heads Wollongong VICTORIA Coburg Frankston Geelong Melbourne Ringwood Springvale Sunshine Thomastown QUEENSLAND Aspley Cairns Ipswich Maroochydore Mermaid Beach Wireless Weather Station Anyone with an interest in the weather will love this station. It has an unbeatable range of features, it is great value, and best of all has no need for messy wiring. The system measures and displays inside and outside temperature, air pressure, rainfall, humidity, wind speed, direction, and chill factor. $ 159 Cat: XC-0293 MORE W EAT STATION HER S IN STOR E • Requires 7 x AA batteries (Use SB-2333) • Indoor display unit 140(W) x 170(H) x 40(D)mm OTHE CHOPP R AVAILABERS IN STOR LE E YOUR LOCAL JAYCAR STORE NEW SOUTH WALES Albury Ph (02) Alexandria Ph (02) Bankstown Ph (02) Blacktown Ph (02) Bondi Junction Ph (02) Brookvale Ph (02) Campbelltown Ph (02) Erina Ph (02) Gore Hill Ph (02) Hornsby Ph (02) Liverpool Ph (02) Newcastle Ph (02) Penrith Ph (02) Rydalmere Ph (02) Sydney City Ph (02) 99 95 Cat: GT-3264 Australia Freecall Orders: Ph 1800 022 888 199 Cat: GE-4063 Cat: GE-4059 Radio Control Apache Attack Chopper 29 95 Cat: GT-3260 Retro Music Centre S 100 USB T Turntable F This handy turntable is GI ER $ perfect for the occasional D bout of nostalgia and allows you N those old vinyl records or U maketo play back-up copies in a convenient • 33/45/78 rpm • 240 volt powered • Magnetic cartridge • NAB centre adaptor • Analogue or digital audio output Note: Laptop not included Powered from your car's cigarette lighter socket, this nifty gizmo enables you to play MP3 files from your USB flash drive or SD card on your car's FM radio. The LCD displays the track playing and transmission frequency. It also has a patch lead so you can connect it to your MP3 player, CD player or other audio device. RC Mini M*A*S*H Helicopter Cat: QP-2258 • 19 range • 3.5 digit • Ideal first meter • Compact size Wireless MP3 Modulator For In-Car Use S 0 FT $5 GI ER D UN Battery, Charger and Alternator Tester Desktop TS $20 ThisBling stapler takes F and will GI ER finishsizeoff56anystaples desk with D style. Two models pink and white or silver and white UN rhinestones. Ph (02) 9531 7033 Ph (07) 5524 6566 Ph (02) 4226 7089 Ph Ph Ph Ph Ph Ph Ph Ph (03) (03) (03) (03) (03) (03) (03) (03) 9384 9781 5221 9663 9870 9547 9310 9465 1811 4100 5800 2030 9053 1022 8066 3333 Ph Ph Ph Ph Ph (07) (07) (07) (07) (07) 3863 4041 3282 5479 5526 0099 6747 5800 3511 6722 Townsville Ph (07) 4772 5022 Underwood Ph (07) 3841 4888 Woolloongabba Ph (07) 3393 0777 AUSTRALIAN CAPITAL TERRITORY Belconnen Ph (02) 6253 5700 Fyshwick Ph (02) 6239 1801 TASMANIA Hobart Ph (03) 6272 9955 SOUTH AUSTRALIA Adelaide Ph (08) 8231 7355 Clovelly Park Ph (08) 8276 6901 Gepps Cross Ph (08) 8262 3200 WESTERN AUSTRALIA Maddington Ph (08) 9493 4300 Midland Ph (08) 9250 8200 Northbridge Ph (08) 9328 8252 Rockingham Ph (08) 9592 8000 NORTHERN TERRITORY Darwin Ph (08) 8948 4043 NEW ZEALAND Christchurch Ph Dunedin Ph Glenfield Ph Hamilton Ph Hastings Ph Manukau Ph Newmarket Ph Palmerston Nth Ph Wellington Ph Freecall Orders Ph (03) 379 1662 (03) 471 7934 (09) 444 4628 (07) 846 0177 (06) 876 0239 (09) 263 6241 (09) 377 6421 (06) 353 8246 (04) 801 9005 0800 452 922 Prices valid to 31st December 2008 Free Call: 1800 022 888 for orders! www.jaycar.com.au 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. 10 Fuzz box for guitars This fuzz box uses low-cost discrete components rather than op amps. It’s designed for use only with amplified guitar signals. While it may appear to be a conventional differential op amp amplifier configuration with Q5 as the long tail for the two input transistors (Q1 & Q2), it actually uses positive rather than negative feedback. It clips symmetrically and the loading of the following amplifier or mixer has no effect on its clipping symmetry. Q4 is connected as a grounded base stage with base bias provided by three diodes: D2, D3 & D4. Q3 drives the emitter of Q4 and the positive feedback signal to the base of Q2 comes via the 4.7kΩ resistor from the collector of Q4. The three diodes also set the bias for Q5 which sets the operating current for the 10k SYMMETRY INPUT 1.5k B Q1 B C C E E Q2 220nF 36k 1.8k C B 100 Q4 C 91 B 1k B Q5 A E 1k A D1 D2 A K K 33nF D3 1k 33nF VR2 2.5k K A 91 DC BALANCE D4 K input pair. Trimpots VR1 & VR2 are used to set symmetry and to zero the DC output voltage. Craig Kendrick Sellen, Philadelphia, USA. ($45) 10 –15V 220nF Q1,Q2,Q4,Q5: BC546 Q3: BC557 D1–D4: 1N4148 B E A C INLINE SWITCH 240V OUTPUT E C 10k E 4.7k 220nF Monitor for pet bed heater This monitor for a pet bed heater was developed because a dog kept rolling over on the bed and causing the heater to become unplugged. When the normally closed (NC) pushbutton is not pressed, current flows through it to the heater element so that it works normally. Conversely, when the button is pressed, the circuit functions as a heater continuity tester, with current passing through diode D1, LED1, the 1kΩ limiting resistor and the heater resistance. As a consequence, LED1 Q3 1.5k VR1 10k +15V K S2 NC PUSHBUTTON D1 12V AC A K 1k A LED1  K HEATER ELEMENT (APPROX 26 ) 1N4004 12VAC PLUGPACK LEDS (LV SOCKET) D1 A is lit to show that the heater is connected to the 12V AC supply. Geoff Coppa, Elanora, Qld. ($30) Editor’s note: a permanent LED K K A monitor could have been arranged by omitting the pushbutton and simply wiring the D1/LED1 circuit in parallel with the heater element, if that could be conveniently done. Issues Getting Dog-Eared? Keep your copies safe with these handy binders. REAL VALUE AT $13.95 PLUS P & P Available Aust, only. Price: $A13.95 plus $7 p&p per order (includes GST). Just fill in and mail the handy order form in this issue; or fax (02) 9939 2648; or call (02) 9939 3295 and quote your credit card number. siliconchip.com.au December 2008  53 Andrew Ar is this m mstrong on winner th’s Peak At of a las Instrum Test ent Circuit Notebook – Continued Circuit Notebook – Continued 1 2.2k Vdd GP1 3x 1.5V CELLS 4 GP3/ MCLR 100nF GP5 IC1 PIC12F675 GP2 GP4 S1 GP0 6 MODE 2 SHUTTER 5 TONE 3 BEEPER 150 150 A 7 8.2k Vss 8 56k 8.2k 56k 22nF Q2 BC548 C E  LED2 8.2k 22nF B K 150 C B  LED1 K Q1 BC548 TO CAMERA REMOTE CONTROL E PIEZO PZ1 A G D Q3 2N7000 S B One-button camera timer This project is a one-button time-lapse camera timer initially developed for a Canon 400D digital SLR camera but it should work with other cameras. You can buy a remote switch for the Canon 400D but that costs at least $35 – a lot of money for what is just a switch on the end of a cable. This circuit adds a nifty timer to the cable in the form of a PIC12F675 microcontroller for about the same price or less if you build it from recycled parts. Once programmed, it can be used to take photographs at intervals from one to 65,535 seconds (ie, 18 hours 12 minutes). It features a single button to control all functions, audible feedback via a piezo transducer and visual feedback via a bi-colour LED. The output from pin 2 of IC1 switches a 2N7000 FET (Q3) which connects the tip of a 2.5mm audio plug to ground in order to activate the camera’s remote shutter function. The sleeve would normally activate the camera’s shutter halfpress function but that is not used by this project. An astable multivibrator comprising transistors Q1 & Q2 and associated components drives the piezo transducer. Since the piezo takes its signal from the collectors 54  Silicon Chip E C 2N7000 LEDS BC548 K A D of Q1 & Q2 it gives a healthy output in spite of the low supply voltage of only 3V. The PIC microcontroller supplies power to the multivibrator via pin 3 to turn it on and off and also sets the tone (high or low) by using pin 5 to switch an 8.2kΩ resistor into the RC network controlling the pitch. Visual indication is provided by LED1 & LED2 which can be single LEDs or a 3-lead bi-colour LED package. The unit powers up in “set” mode which is indicated by red LED1. You then select the time-lapse interval (in seconds) by pressing the button. The first press emits a low beep, indicating zero, then subsequent presses emit high beeps which you count until you reach the next digit you want. Digits are entered as you would write them on paper, so 120 seconds would be entered as 1, then 2, then 0. To enter each digit, all you have to do is wait for one second or more. You will then hear a high/low beep. If you overshoot the digit, you just keep pressing until you hear the low beep indicating zero and start over. Once the time-lapse interval has been entered, you switch into “shoot” mode by holding the button down for one second or more until G 10k S you hear a high beep. LED1 will extinguish and LED2 will briefly flash every time a shot is taken. Shooting begins as soon as you release the button. This has a useful side-effect in that if you want to start your shooting at a particular time, you just keep holding the button down while looking at your watch. It will give you “timing” beeps at one-second intervals so you can release the button to start shooting at a particular instant. The last time-lapse interval set is remembered. To use the previously set interval, just press and hold the button after power up and “shoot” mode will be started using that interval. To temporarily suspend shooting, tap the button for less than one second. You can resume shooting using the existing interval by holding the button down for more than one second. The software will be available for download from www.siliconchip. com.au To program the PIC12F675 you will new to purchase a programmer such as the Microchip PICKit 2 and obtain a C compiler such as the free version of MikroC. Andrew Armstrong, Dural, NSW. siliconchip.com.au siliconchip.com.au 3 SPEAKER 2 4 100nF 7 5 8 1 IC2 LM386N 10 F 6 100nF VOLUME VR3 50k BC547 100nF D3 K A B D1,D2: 1N34, ETC 3.9k C Q3 BC547 10k 15k 1nF 1k * 1x FM SECTION OF POLYCON RFC2 E VC1* TUNING ANTENNA 10nF E 10nF 15k L1 DETAILS: 4 TURNS OF 0.9mm ECW, 3mm INTERNAL DIAMETER AND SPACED 10mm APART (TUNES 100 – 140MHz) 15k 1nF 10nF 1k VR1 B C 6.8pF C B Q1 BC547 E 3.3nF 3.3nF 1M 4 IC1 TL081 2 3 7 6 A 10nF K A K A D1 D2 K 1 F 10k B B E C BF494 5k SQUELCH E C VR2 Q4 BC547 E B 100 F C 22k K 22k 22k 100nF Q2 BF494 100nF L1 RFC1 4.7pF 27k Inductor L1 is wound on a 3mm former with four turns of 1mm enamelled copper wire. RFC1 & RFC2 are standard 10μH moulded chokes while VC1 is the FM section of a standard plastic dielectric tuning capacitor. This gives enough range to tune from 100MHz to 140MHz. All the capacitors in the RF section should be disk ceramics. Potentiometer VR1 adjusts the bias on the detector (Q2) and maximum sensitivity is at the point where the hiss is stable at the earthy end of the adjustment. At this point, about 1.5-2V will appear across the 1μF capacitor with the squelch control set fully open. This setting will remain fairly constant over the complete tuning range. When adjusted correctly, the squelch will “spit” on background noise. Dayle Edwards, Taylorville, NZ. ($60) 150 Winding inductor L1 A D3 1N4148 Bandpass filter The recovered audio modulation from inductor RFC2 is fed via emitter-follower stage Q3 to op amp stage IC1 which acts as a narrow bandpass filter. It rejects the high quench content of the input signal and any voice modulation. Its output is rectified by diodes D1 & D2 and filtered by a 1μF capacitor. This becomes the squelch control voltage for Q4 which turns on to reverse-bias diode D3. This prevents signal from the emitter of Q3 from being coupled through D3 to the input of the audio stage, IC2. Hence, when signal is present, the receiver “quiets” on receipt of a carrier and squelch voltage to Q4 falls, turning it off. Thus the collector voltage of Q4 rises and forward biases D3 to allow the audio signal through to the volume control, VR3. Potentiometer VR2 acts as the squelch control. 10 220 F 9V BATTERY 100 F 16V 4.7k This VHF receiver offers very good performance with few components and covers the whole commercial air band from just above 100MHz to 140MHz with sensitivity of just a few microvolts. It has a noise squelch circuit, for pleasant noise-free listening a very pleasurable experience. The antenna is coupled via a 10nF capacitor to the base of transistor Q1, a grounded base buffer stage. It isolates the antenna from the following stage involving Q2 which acts as a super-regenerative detector. The detector is self-quenched at around 20kHz via the combination of the 15kΩ resistor and 1nF capacitor associated with inductor RFC2. S1 VHF aircraft receiver with squelch December 2008  55 Circuit Notebook – Continued STOP1 5 ON/OFF +9V 16 Vdd IC1b 4 3 1 2 14 IC1a 5.6M 470k O0 3 22nF CP1 IC2 4017B CP0 O1 2 A A  O2 4 A O3 7 D  K A Vss O4 O5 1 10 G MR O6 5 J A  K K 9 10 5.6M 7 6 560k 14 15 D E F 1k K +9V O0 3 22nF CP1 IC3 4017B CP0 O1 2 A B  O2 4 A O3 7 E  K A Vss O5 1 10 MR O6 5 K N O4 H A  K A  K 13 8 14 15 11 12 14 CP0 5.6M 680k 22nF O0 3 O1 2 O2 4 O3 7 I J K L M N O D1 3 6 A 4 IC5a 5 D2 11 10 A 12 IC5c 13 7 D3 C  K A  K F A Vss O4 O5 1 10  K A  K PIEZO BUZZER K +9V D4 K D5 3 6 A 4 IC6a 5 7,11, 12,13 4.7k K B C Q1 BC547 E +9V CP1 I K 1 14 9 A 2 IC6b 8 MR 13 47k IC1: 4049B IC5,IC6: 4073B 8 15 BC547 O6 5 L A K A C O D1–D5: 1N4148  K LEDS B E A K 1k K IC4 4017B 8 H 1 14 9 A 2 IC5b 8  K 16 Vdd IC1e 47k G 15 STOP3 IC1f A B C 8  K 16 Vdd IC1c 47k M A  13 STOP2 IC1d 9V 1k A K 0V Toy poker machine is no risk to wallet This poker machine circuit can be built to help the young (and not so young) understand the folly of the real thing. It demonstrates the very high odds of not winning, regardless of the “win” conditions. Six inverters in IC1, a 4049, are paired to provide three independent clock oscillators which run at 56  Silicon Chip different speeds. These clocks drive three 4017 decade counters, IC2, IC3 & IC4. Each decade counter uses six of its outputs and they are set back to zero each time they reach a count of 6. Five of the outputs drive five LEDs – red, green, yellow, blue and white – and they flash at different rates, depending on the clock oscillators. Each counter is provided with a stop switch so that the counts can be stopped at will, randomly. The aim is to get a winning set: three greens, three reds, etc. By adding five 3-input AND gates (IC5 & IC6), a piezo buzzer can be made to sound if a winning combination occurs. The outputs of the five AND gates are ORed by the five diodes to drive transistor Q1 and the buzzer. The folly of the poker machine becomes apparent when the odds siliconchip.com.au Battery monitor has low current drain This circuit makes use of an ultrabright red LED to produce a low battery-warning indicator which pulls very little current. As shown, it suits a 9V battery and the LED only lights if the supply voltage drops below about 7.6V. At that point, the battery is on its last legs so the operating current of the LED will have little effect on its remaining life. When the voltage is above about +7.6V, the 7.5V zener diode (ZD1) of winning are considered. There are 216 possible combinations of the three counter outputs and five of these, matching colour sets, are winners. Since the pin 3 output of each counter can occur but has no LED connected, this is a no score condition. So the chances of winning are 5 in 216 or 43:1 against. Not good. If you nominate, say, three blues as a special prize, it will come up once in every 216 games, on average. In a real poker machine, the odds are a great deal worse, since it has many symbols in each row and “N” rows rather than three. To the logical mind, pokies have no appeal at all. A. J. Lowe, Bardon, Qld. ($60) will conduct to turn on transistor Q1. This in turn shunts current away from the LED. Conversely, when the voltage drops below 7.6V, the zener diode and the transistor will stop conducting and the LED will light. Total current drain from a fresh 9V battery will be of the order of 0.1mA, dropping very slightly as the LED comes on. Steven Graham, Christchurch, NZ. ($30) + K 9V BATTERY ZD1 7.5V 82k A 100k B C E A Q1 BC547 K LED1  (ULTRA BRIGHT) – A BC547 LED ZD1 K B K A E C Editor’s note: this circuit would normally be wired in after the equipment’s power switch. From the publishers of SILICON CHIP PERFORMANCE ELECTRONICS FOR CARS NOT A REPRINT: More than 160 pages of new and exciting projects never published before – all designed to get top performance from your car. FASCINATING ARTICLES: 7 chapters explaining your car – engine management, car electronics systems, etc ADVANCED PROJECTS: You’ll build controllers for turbo boost, nitrous, fuel injection and much more! We explain the why as well as the how to! Available direct from the Publisher ($22.50 inc postage): Silicon Chip Publications, PO Box 139, Collaroy NSW 2097. Ph (02) 9939 3295; Fax (02) 9939 2648; email silchip<at>siliconchip.com.au or via our website: www.siliconchip.com.au Contribute And Choose Your Prize As you can see, we pay good money for each of the “Circuit Notebook” items published in SILICON CHIP. But now there are four more reasons to send in your circuit idea. Each month, the best contribution published will entitle the author to choose the prize: an LCR40 LCR meter, a DCA55 Semiconductor Component Analyser, an ESR60 Equivalent Series Resistance Analyser or an SCR100 siliconchip.com.au Thyristor & Triac Analyser, with the compliments of Peak Electronic Design Ltd www.peakelec.co.uk So now you have even more reasons to send that brilliant circuit in. Send it to SILICON CHIP and you could be a winner. You can either email your idea to silicon<at>siliconchip.com.au or post it to PO Box 139, Collaroy, NSW 2097. December 2008  57 CHRISTMAS SHOWCASE Santa’s Sack mgrm299:Layout 1 NIXIE CLOCK 2:48 PM Page 1 of MicroGram Goodies • Car PC Kit – 12v PC and 8” LCD Touchscreen Cat 1168-7 $1999 • CD/DVD Carousel – Find movies, music, games, data quickly Cat 6303-7 $259 • Voice Activated Universal Remote Control Cat 9526-7 $389 • Cordless Media Centre Keyboard with Trackball Cat 1008316-7 $139 • Cordless Presenter “Pen Mouse” Cat 9287-7 $129 • Cordless Skype & Landline IP Phone Cat 10245-7 $119 • USB Headset – Great for music, gaming and VOIP Cat 3549-7 $55 • 100 Spindle Ritek ‘A Grade’ DVD-R 16x • USB to VGA Adapter – Add more screens to your PC Cat 15179-7 $197 • USB Microscope – Easy to install & operate Cat 3626-7 $239 Cat 1168 Cat 6303 Cat 9526 Cat 9287 Cat 10245 Cat 7038-7 $42.50 Cat 15179 Cat 3626 MicroGram Computers Unique IT Solutions 1800 625 777 ask<at>mgram.com.au www.mgram.com.au All prices subject to change without notice. For current pricing visit our website. Pictures are indicative only. SHORE AD/MGRM299 Kit 10/11/2008 QUICK860D ESD – HOT AIR SMD Rework Station ‘Christmas ‘September Special’ Special’ A$248.00 pleasequote quote this this ad A$248.00 please This will blow you away… Your No. 1 choice in high performance & low cost of ownership Features: − Extremely low flow rate designed for small component soldering − Precise and stable temperature are not influenced by air volume − Light handle, sleep mode and easy to operate − Cooling air function to prolong the life of heater − 6 different Nozzles included Specifications: − − − − − Power consumption: 120W Temperature Range: 100°C - 450°C Air Volume: 0.3 – 6.8 ltr/min, stepless Heating mode: ceramic heater Noise: <60dB For more information please contact us: 2 Salisbury Street Botany NSW 2019 Tel: (02) 9695 1030 Fax: (02) 9695 1944 E Mail: info<at>onboardsolutions.com Website: www.onboardsolutions.com CHRISTMAS SHOWCASE 58  Silicon Chip siliconchip.com.au CHRISTMAS SHOWCASE POCKET-SIZED HF RECEIVER SPECIALS FROM AV-COMM Degen 1103 $159 Cat # Q3050 Economical yet fully featured, the Degen 1103 receiver offers AM and SSB reception and direct frequency entry anywhere from 100 to 29999kHz as well as standard AM and FM stereo modes. Over 200 memory positions ensure you'll be able to store all your listening requirements. Supplied with rechargeable batteries, charger, carry case, earphone and 10m longwire antenna, this receiver caters for all your holiday listening needs. Tecsun PL 600 The Tecsun PL 600 is the big brother to the Degen 1103, and offers the same modes and frequency coverage, as well as expanded storage capability to 600 memory positions. Slightly easier to use than the Degen, this receiver has a larger LCD frequency and signal strength display, and larger BFO control to make tuning SSB signals easier. Supplied with the same accessories as the Degen, the PL 600 performance is identical, offering sensitivity of less than 1uV for SSB reception on all HF frequencies. Cat # Q3049 $179 Av-Comm Pty Ltd www.avcomm.com.au Tel: 02 9939 4377, Fax: 02 9939 4376 P.O. Box 225 Brookvale NSW 2100 Australia Unit 24, 9 Powells Road, Brookvale, NSW Only Hills can offer you a total HIGH DEFINITION TV package! For the ultimate in TV reception, have a Hills Platinum High Definition antenna coupled with a Hills HD08 HD Set Top Box installed in time to catch all your favourite sporting events in 1080i pictures. The antenna is HD & SD digital compatible and it is engineered for Australian digital channels. Designed with strong aluminum boom & elements for superior corrosion resistance. Features: • Suitable for channels 6-12 & 28-36 • Capital City Digital Channels • Reduce Impulse Noise • Ultrasonically Sealed PCB F type housing • Clamshell insulators to provide positive element locking • Compact and lightweight • Quick and easy site installation • Designed and made in Australia for Australian conditions. The Hills HD08 High Definition Set Top Box allows you to enjoy all your favourite HD programs currently broadcasted as well as all your standard definition channels. The unit offers superior resolution at the highest level (1920 x 1080) together with high quality sound, more channel selection with wide screen 6 x 9 picture format. Features: • HDMI output • Simultaneous HD/SD output • 7 days Electronic Program Guide (EPG) • Video output selection: HDMI, RGB (D-Sub), Component , S-Video, Composite (YPbPr) • AC-3 Audio Output • Supports 1080i, 720p, 576p, 576i Video Format • Favourite Channel List & Editing • Dolby R Digital 5.1 Channel Surround Sound. Contact your Hills local branch for more details Riverwood Ph: (02) 9717 5290 Acacia Ridge Ph: (07) 3344 3855 Keysborough Ph: (03) 9238 2533 Edwardstown Ph: (08) 8371 0277 Castle Hill Ph: (02) 9894 9444 Arundel Ph: (07) 5500 7222 Derwent Park Ph: (03) 6273 9973 Malaga Ph: (08) 9209 7000 CHRISTMAS SHOWCASE siliconchip.com.au December 2008  59 Brownout Protector By JOHN CLARKE Protects AC motors against low AC mains voltage What is a “brownout”? This rather graphically describes what happens to your lights when the AC mains voltage drops dramatically – they get very dim. But apart from dim lights, brownouts are a fatal hazard to induction motors, as used in air conditioners, pumps, dishwashers and a lot of other appliances. Y EARS AGO, BROWNOUTS were quite rare and generally confined to rural districts where the power lines had very long runs. A falling tree or an electrocuted possum might cause the mains voltage to drop to a low level and lights would go dim. This has always been a hazard for the induction motors used in pumps and refrigerators. Nowadays though, because the electricity grid is running much closer to total capacity, brownouts can be experienced much more commonly in the cities and suburbs. Our own offices in the Sydney suburb of Brookvale have had brownouts on a number of occasions in the last year or so. On each Main Features • Adjustable threshold voltage • Switches up to 2300W • Power indication • Brownout indication • Rugged sealed enclosure 60  Silicon Chip occasion, we have made sure that the air conditioner, fridges, compressors and other machinery in the building were turned off until full AC mains supply was restored. Had we not done so, all the motors in that equipment were liable to burnout. So how many motors in your home are at risk right now if a brownout was to occur? The list can be quite long: fridge, freezer, washing machine, dishwasher, air conditioner, pool pump, spa pump and perhaps one or two garage door openers; typical of many homes. All this equipment could attempt to turn on during a brownout and the motor(s) would probably burn out. Specifications Standby power consumption: <5W with relay on Maximum Control Power: 2300W Brownout threshold voltage: typically set to 200V Switch on delay: 5 seconds Maybe your insurance policy covers motor burnouts but you would need to read the fine print. The insurance company might also look askance at your claim if there was more than one motor burnout or if the appliances were more than a few years old. Why do motors burn out? When induction motors are starting up they draw very heavy current for a second or two and when they are up to speed, the current drops back to reasonable levels. However, if the AC mains voltage is low, the induction motor may not develop enough torque to come up to full speed. In all of the appliances listed above, the motor starts with a heavy load so it is at particular risk if those starting currents do not reduce quickly. Those motors with a starting winding (switched out by a centrifugal switch) are at particular risk because those windings are only intended for very intermittent use. By the way, some motors do have thermal cut-outs but these cannot be regarded as a panacea – they are more correctly regarded as fire preventive siliconchip.com.au rather than protecting the motor from any damage. So there you have the reasoning behind our Brownout Protector. If you have a couple brownouts every year, you need protection for your appliances. You cannot rely on the possibility that you will be at home or awake when a brownout occurs and that you will be able to turn off all of the at-risk appliances before they are damaged. And unless the appliances are all in a single location (unlikely!), you need one Brownout Protector for each appliance you wish to protect. Above: the Brownout Protector is housed in a rugged ABS plastic case with a clear lid. It can be used with induction motors rated up to 2300W and you will probably need one for each appliance you wish to protect. Features The SILICON CHIP Brownout Protector provides constant protection for any single-phase induction motor, disconnecting power when the AC mains voltage drops below a preset level and then reconnecting it when the voltage returns to normal. The cost of this protection is far less than the likely cost of repair and replacement of a typical small induction motor. It may be used with induction motors rated up to 2.3kW (10A). siliconchip.com.au Power is applied to the unit via a switched IEC connector attached to one end of the case. Note that this connector and its internal mounting plate must be secured using Nylon screws to ensure safety. December 2008  61 GPO F1 10A A SLOW BLOW S1 12.6V K 0V T1 12.6V/7VA E K D5 A K A K K A A 10 F 16V A A  LED1  LED2 K K 100k 10 F 16V 560 VR1 50k 2 TP1 8 3 1 IC1a IC1: LM358 10k ZD1 3.9V 100k A IC1b 6 E 100nF 7 2.2k C B E Q1 BC337 470 SC  2008 B K A E D1–D6: 1N4004 A BROWNOUT PROTECTOR A K A 7812 C GND K D7: 1N4148 ZD1 BC337 LEDS A SET VR1 SO DC VOLTS AT TP1 = (Vmains/100) E.G., 230V/100 = 2.3V SET VR2 SO DC VOLTS AT TP2 = (Brownout Volts/100) E.G., 200V/100 = 2.0V Q2 BC337 K 4 VR2 50k B D7 5 TP2 K C 10k +12V C2 100 F 16V 2.2k POWER TP GND A 100 F 16V D6 2.2k C1 470 F 25V E K GND A N A 30A AC CONTACTS +12V OUT IN D1–D4 6.3V 240V N RLY1 REG1 7812 K IN GND OUT Fig.1: the circuit monitors the rectified DC voltage at the output of bridge rectifier D1-D4. This voltage is fed via VR1 to voltage follower IC1a which in turn drives comparator stage IC1b. IC1b then drives transistor Q1 to control RLY1. Note that since the year 2000, the electricity suppliers are obliged to follow Australian Standard AS60038 where mains voltage should be 230VAC with a tolerance of +10% and -6%. That means that the voltage could drop to 216V at the lower tolerance limit. Our circuit sets the switching threshold to 200VAC to avoid nuisance tripping during normal supply conditions. A heavy-duty relay does the switching. While ever the mains voltage is normal, the relay contacts are closed and power is available to the load (motor). If the mains voltage drops below 200VAC for more than five seconds, the relay contacts open to protect the motor. The relay contacts are rated for inrush currents of up to 65A – ideal for switching power to a motor which is pulling heavy starting currents. Circuit details The full circuit is shown in Fig.1. It comprises just a few low-cost components. These include a dual op amp (IC1), a couple of transistors, a 12V 62  Silicon Chip regulator and the heavy-duty relay. Power for the circuit is derived from the mains via a 12.6VAC stepdown transformer, T1. This drives a full-wave rectifier using diodes D1-D4 and a further diode, D5, before filtering with a 470μF capacitor (C1). The resultant nominal 17V DC is applied to the 12V 7812 3-terminal regulator (REG1). REG1 provides the 12V supply for IC1 and the 12V relay. Brownout detection To detect a brownout condition, the circuit needs to monitor the AC voltage from the transformer secondary winding. In practice, we don’t do this directly but instead monitor the rectified DC waveform at the anode of diode D5. This is filtered using a 100kΩ resistor and by a 100μF capacitor (C2) which is shunted by 50kΩ trimpot VR1. The resulting DC voltage across C2 is about 3.6V. Note that this voltage does not necessarily track the 16V or so that appears across capacitor C1. This is because C1 charges to the peak of the rectified 12.6V waveform whereas the 100kΩ resistor, trimpot VR1 and 100μF capacitor (C2) form an averaging filter to give a lower voltage (Vp x 0.636 x 150kΩ/50kΩ ~3.6V). OK, so why go to all this trouble rather than just monitoring the DC voltage across capacitor C1? After all, if the mains voltage varies, the voltage across C1 will vary in proportion, will it not? The reason for using the averaging filter method is twofold. First, the actual AC waveform of the mains supply is usually “flat-topped” due to the loading effects of gas discharge lighting (eg, fluorescents) and the capacitor-input power supplies used in all computers and most electronic equipment. Using the peak of the waveform to represent the actual mains voltage is not sufficiently accurate because the degree of “flat-topping” varies during the day, depending on whether it is peak or off-peak period. Second, when the relay switches on and off, it causes a considerable variation in the voltage across C1. For example, across C1 we measured siliconchip.com.au 15.8V with the relay energised (on) and 17.45VDC with the relay off, a variation of more than +10%. By contrast, the variation in the “averaged” voltage across C2 was 3.6V with the relay on and 3.75V with the relay off, a variation of just over 4%. This is important because in the worst case, the brownout detector needs to respond to an actual variation in mains voltage from 216V (the normal minimum mains voltage) to 200V (the switching threshold). This is a variation of only 7.5% and we don’t want the circuit being confused by variations in the supply waveform. Trimpot VR1 is included so that the sample voltage fed to op amp IC1a is exactly 1/100th of the mains AC voltage value. To give an example, if the mains voltage is 230VAC, trimpot VR1 is adjusted so the DC voltage at the output of IC1a, at TP1, is exactly 2.3V. This is part of the calibration procedure and just why we do this will become clear in a little while. The voltage at TP1 is fed to the noninverting input (pin 5) of op amp IC1b which is connected as a comparator. A nominal 3.9V reference is provided by zener diode (ZD1) which is fed via a 560Ω resistor from the +12V supply. Trimpot VR2 sets the switching threshold for IC1b and its wiper is connected to IC1b’s pin 6 inverting input. Pin 6 is set to about 2.00V (representing a brownout threshold detection point of 200VAC). So with a normal mains voltage, pin 5 will be at 2.3V (representing a 230VAC mains voltage). This voltage is higher than the 2V at pin 6 and so the output of IC1b will be high (close to 12V). This switches on transistor Q1 which powers the relay (RLY1). The relay’s contacts supply power to the appliance connected to the GPO. When IC1b’s output is high, diode D7 will be reverse biased and so the 100kΩ resistor at pin 5 does not affect circuit operation. However, should the mains voltage drop to just below 200VAC, the voltage at pin 5 will go below the 2V threshold set at pin 6 and so pin 7 of IC1b will go low. This will switch off transistor Q1 and the relay, to disconnect power from the load. Diode D6 quenches the back-EMF from the relay when its magnetic field collapses, protecting Q1 from damage. Simultaneously, transistor Q2 switches on to light the brownout siliconchip.com.au Parts List 1 PC board, code 10112081, 152 x 108mm 1 IP65 ABS enclosure with clear lid, 171 x 121 x 55mm (Jaycar HB-6248 or equivalent) 1 2853 12.6V 7VA mains transformer (T1) 1 12V coil relay with 30A 220VAC contacts (Jaycar SY-4040 or equivalent) 1 IEC snap-fit chassis fused male connector with switch 1 10A M205 slow-blow fuse (F1) 1 10A IEC mains cord 1 10A mains panel socket with side wire entry 1 20°C per watt heatsink (19 x 19 x 10mm) 2 2-way PC-mount screw terminal blocks, 5.08mm spacing 1 72 x 27mm sheet of 1mm aluminium or steel 5 6.4mm insulated spade connectors for 1mm2 wire 1 6.4mm piggyback spade connector for 1mm2 wire 4 4.8mm spade connectors for 1mm2 wire 1 5.3mm ID eyelet terminal for 1mm2 wire 2 M4 x 10mm screws 4 M3 x 6mm screws 3 M3 x 10mm screws 4 M3 x 15mm Nylon countersunk screws 2 M4 nuts 7 M3 nuts 3 3mm ID star washers indicator, LED2, via a series 2.2kΩ current-limiting resistor. Hysteresis When IC1b’s output is low, D7 conducts and pulls pin 5 even lower than 2V due to the voltage divider action of the 100kΩ and 10kΩ resistors. For example, if the voltage at TP1 is at slightly less than 2V, the output of IC1b will very close to 0V. The anode of D1 will be about 0.5V and so the divider action caused by the 10kΩ resistor connecting to 2V and the 100kΩ resistor connecting to 0.5V will give a voltage at pin 5 of (2.00 - 0.5V) x 100/110 + 0.5V, or 1.86V. This is a drop in voltage of 140mV. So instead of pin 5 now being at 2V, 2 4mm ID star washers 2 4mm ID flat washers 9 100mm cable ties 1 100mm length of 10A blue mains wire 1 150mm length of 10A brown mains wire 1 150mm length of 10A green/ yellow mains wire 1 100mm length of medium duty hookup wire 1 100mm length of 10mm heatshrink tubing 3 PC stakes 2 50kΩ horizontal trimpots (code 503) (VR1,VR2) Semiconductors 1 LM358 dual op amp (IC1) 1 7812 12V regulator (REG1) 2 BC337 NPN transistors (Q1,Q2) 1 3mm green LED (LED1) 1 3mm RED LED (LED2) 1 3.9V 1W zener diode (ZD1) 6 1N4004 1A diodes (D1-D6) 1 1N4148 switching diode (D7) Capacitors 1 470μF 25V PC electrolytic 2 100μF 16V PC electrolytic 2 10μF 16V PC electrolytic 1 100nF MKT polyester (code 104 or 100n) Resistors (1/4W, 1%) 2 100kΩ 1 560Ω 1 10kΩ 1 470Ω 3 2.2kΩ the action of the 100kΩ resistor, diode D7 and the 10kΩ resistor reduces the voltage by about 140mV, ie, to 1.86V. Before IC1b’s output can go high again, the mains voltage would have to rise by the extra amount to make up this 140mV difference. This requires an increase in mains voltage of 14VAC. In practice though, because the average voltage at TP1 is higher when the relay is off compared to when it is on, the extra voltage required from the mains for the relay to switch back on again is about 10V. This voltage difference effect is called “hysteresis” and is included to prevent the relay from rapidly switching on and off at the brownout threshold. December 2008  63 4004 4004 2.2k 100k 470 F H CTI WS TU O N W OR B TP GND TP1 100 F 100nF 1 560 ZD1 TP2 2.2k 1 2 2 RLY1 2 IEC MAINS CONNECTOR WITH SWITCH AND FUSE (REAR VIEW) MAINS WIRING CONNECTORS: 1: 6.4mm INSULATED SPADE CONNECTORS 2: 4.8mm INSULATED SPADE CONNECTORS 3: 6.4mm PIGGYBACK SPADE CONNECTOR 100 F 10k LED2 BROWN OUT CON2 4004 2 D7 470 VR2 50k 3V9 3 4148 IC1 LM358 M3 x 10mm SCREW WITH LOCK WASHER & NUT 1 10 F 10k VR1 50k 1 K LED1 POWER 10 F 2.2k 2853 N A CON1 T1 100k 4004 4004 REG1 7812 PRIMARY A SEE DETAIL DIAGRAM SECONDARY GPO (REAR VIEW) E D1 D2 D3 D4 D5 4004 18021101 A K D6 1 Q1 Q2 M4 x 10mm SCREWS WITH FLAT & LOCK WASHERS, NUTS NOTE: ALL WIRING TO THE IEC CONNECTOR, THE GPO, AND THE OUTPUT CONTACTS ON THE RELAY (1) MUST BE RUN USING 240VAC CABLE Fig.2: follow this diagram to assemble the PC board and complete the wiring. Mains-rated cable is used for all wiring to the GPO, IEC connector and relay output contacts and this wiring must be secured using cable ties. Provided that the mains voltage remains below the brownout threshold, the relay will remain off. In fact, the relay remains off at any voltage below the threshold, including voltages down to 0VAC. A power-on delay is included so that the relay only switches on about five seconds after power is applied. This delay is due to the values of the 100kΩ and 100μF filter components that monitor the average voltage from the rectifier. These are sufficiently large so that it takes time for the 100μF capacitor to charge up to above the voltage provided at TP2. This delay is also important to allow for the inevitable momentary drop in mains voltage which is caused by the high surge currents every time an induction motor starts up. Normally, these high currents only last a second or two, depending on the appliance, and we want to be sure that they do 64  Silicon Chip not cause the Brownout Protector to erroneously switch off the power. CRIMP EYELET STAR WASHERS TRANSFORMER MOUNTING FOOT Construction The Brownout Protector is housed in a weatherproof ABS enclosure (171 x 121 x 55mm) with a transparent lid and neoprene lid-sealing gasket. The box is designed to meet the IP65 dust and moisture ingress standard, although this standard is compromised somewhat by the addition of the GPO and IEC socket. All of the parts, except the GPO and IEC connector, are assembled onto a PC board coded 10112081 and measuring 152 x 108mm. This board has corner cut-outs at one end to allow it to sit on the base of the box. The IEC mains input socket with on/ off switch and integral fuse is mounted in one end of the case and a 3-pin AC socket is mounted on the transparent lid. The two LEDs on the PC board can M3 NUT PC BOARD M3 x 10mm SCREW Fig.3: an M3 x 10mm screw & nut, two M3 star washers and a crimp eyelet are used to secure the earth wire to the transfomer frame. be clearly seen through the transparent lid so the overall assembly is very straightforward. The complete wiring diagram is shown in Fig.2. Begin construction by checking the PC board for any defects such as shorted or broken tracks. That done, check that the hole sizes are correct. The holes for the four corner mounting screws, for REG1 and for the transformer mounting points need to be 3mm in diameter, while the holes for siliconchip.com.au the relay mounting screws should be 4mm in diameter. Check also that the main PC board is cut and shaped to size so that it fits into the box. Insert the resistors first, taking care to place each in its correct position. Use the resistor colour code table when selecting each value. You can also use your digital multimeter to check each resistor before installing it. Next, install PC stakes for test points TP1, TP2 & TP GND. That done, install the 1N4004 diodes (D1-D6), the 1N4148 diode (D7) and zener diode ZD1, taking care with their orientation. IC1 can be mounted next (watch its orientation), followed by the capacitors. Note that the electrolytic types must be oriented as shown. The 3-terminal regulator (REG1) is mounted on the PC board with a small finned heatsink. It leads need to be bent to fit into the holes provided and then it is secured on the heatsink with an M3 x 10mm screw and nut and its leads soldered. Next, install trimpots VR1 & VR2, transistors Q1 & Q2, LEDs 1 & 2 and the two 2-way screw terminals CON1 & CON2. The transistors and LEDs sit a few millimetres above the PC board. The relay is secured using M4 screws and nuts while the transformer is attached using M3 screws and nuts. The transformer must be earthed and this is achieved using a short green/ yellow earth wire with crimped eyelet. This is attached to one of the transformer mounting feet with two star washers, above and below the eyelet – see Fig.3. Note that the enamel must be scraped from the transformer foot to ensure good contact. The IEC fused male socket and switch is a snap-in type intended for use with a mounting plate thickness of about 1mm. Unfortunately, the specified IP65 box has a wall thickness of 3mm so the socket cannot be mounted directly to it. Instead, the IEC socket is first mounted on a 1mm thick metal plate and this plate is then secured to This is the view inside the completed unit. Take care to ensure that the GPO is wired correctly and that the mains earth leads are properly terminated. the inside of the box using four Nylon screws and metal nuts. As a result, the flange of the IEC socket is mounted flush with the surface of the box, giving a neat finish. Diagrams for the metal plate, the box cut-out and the socket cutout in the box lid are shown in Figs.4-6. Note that the end of the box for the IEC cut-out is best located at the same end as the Table 1: Resistor Colour Codes o o o o o o siliconchip.com.au No.   2   1   3   1   1 Value 100kΩ 10kΩ 2.2kΩ 560Ω 470Ω 4-Band Code (1%) brown black yellow brown brown black orange brown red red red brown green blue brown brown yellow violet brown brown 5-Band Code (1%) brown black black orange brown brown black black red brown red red black brown brown green blue black black brown yellow violet black black brown December 2008  65 The PC board is secured to the bottom of the case using self-tapping screws that go into integral standoffs. The IEC socket is attached by first clipping it to an aluminium mounting plate (see Fig.5), then fitting it inside the case and securing the plate using four Nylon screws and metal nuts (see photos). two sets of mounting bushes located on the base of the box (see photo). Note also that the cutout in the box should be just enough to provide clearance for the flange of the IEC socket. Once the IEC connector has been secured in place, you can install the PC board. To do this, you will need to first slide the edge of the PC board under the IEC connector. The PC board is secured using for M3 x 6mm screws into the integral threaded mounting bushes on the base of the box. Wiring All wiring must use 250VAC 10A rated wire except for the relay coil wires to CON2. Brown wires are used for the Active and the blue for the Neutral. The green/yellow-striped wire is for the Earth wiring and must not be used for any other wiring. Note that the mains wires termi66  Silicon Chip nated at the IEC socket and on the relay will need to use insulated crimp connectors. You must use a ratchetdriven crimp connector to fit these. Do not use a cheap automotive-style crimp tool, as this will not give reliable connections. Note that the crimp connections to the relay will need to be bent over slightly so that the lid can fit without fouling. All wiring must also be secured with cable ties to prevent a loose wire moving and making contact with the low-voltage components on the PC board. We did this with nine cable ties, as can be seen in the photographs. The two Neutral wires are also tied to the 3-pin socket using the holes on its moulding. Initial checks Before doing anything else, use your multimeter (set to a low ohms range) to check between the earth pin of the IEC connector and the earth outlet of the GPO. You should get a reading of zero ohms here (this checks the integrity of the earth connection). Similarly, you should get a reading of zero ohms between the earth pin of the IEC connector and the transformer frame. Having verified the earth connection, fit the 10A fuse to the fuseholder in the IEC socket. Note that this fuse should be a slow-blow type. Testing When you are testing and making adjustments, the Brownout Protector will need to be operated with the lid open. You must take care not to touch any of the connections in the 250VAC section when it is plugged into a wall socket, even though they are insulated by the crimp connectors (it is wise to be careful). This includes the wiring to the GPO, IEC connector, transformer primary and relay contacts. First, set your multimeter to read up to 250VAC and insert its insulated siliconchip.com.au Points To Check 4.5mm DIAM. 26 33.5 14 10.9 16.75 40 (BOX LID) (1) Be sure to use the specified ABS plastic case & note that Nylon screws must be used to secure the IEC connector plate. (2) Use mains-rated cable for all connections to the IEC socket, the GPO and the relay contacts. Secure this wiring using cable ties – see photos. (3) Use insulated spade connectors to terminate the leads to the IEC connector and to the relay contacts. A ratchetdriven crimping tool is necessary to fit the spade connectors. (4) Do not touch any part of the 250VAC wiring while this device is plugged into the mains. Also, DO NOT attempt to build this device unless you know what you are doing and are familiar with high-voltage wiring. 5 10 A A (END OF BOX) A 72 47 13.5 siliconchip.com.au 10 A A Further testing can be done if you have access to a Variac. This can be used to reduce the mains voltage to check that the brownout detection operates at the required voltage. If you do not have access to a Variac, then you can adjust VR1 so that the TP1 voltage drops just below the TP2 voltage. When it does, check that the relay switches off and that the brownout LED lights. Return VR1 to its correct position after this test and secure the lid with the four screws. That completes the setting up. The Brownout Protector can now be used 6 probes into the Active and Neutral terminals of a mains outlet. Measure the mains voltage, then remove the probes from the mains outlet and switch on the Brownout Protector. Wait for the relay to switch on, then measure the DC voltage between TP1 and TP GND (or the mounting screw of the 3-terminal regulator). Next, adjust trimpot VR1 for a reading of the mains voltage divided by 100. As previously suggested, if the mains voltage is 230VAC, set test point TP1 to 2.3V. Finally, adjust trimpot VR2 to set test point TP2 to 2.00V. 18 Fig.5: the cutout and drilling diagram for the IEC connector at the end of the box. IEC CONNECTOR MOUNTING PLATE: MATERIAL 1mm SHEET ALUMINIUM OR STEEL A 50 5.5 5 A 27 30 CUTOUT FOR IEC CONNECTOR 6 18 HOLES A: 3.0mm DIAMETER CORNER RADIUS 2.5 A 18 CL 25 5.5 4.0 38 Fig.4: the cutout and drilling diagram for the GPO socket in the case lid. The large cutout can be made by drilling a series of small holes around the inside perimeter, then knocking out the centre piece and carefully filing the job to a smooth finish. Fig.6: follow this diagram to make the mounting plate for the IEC connector. as is or you can mount it on a wall adjacent to the appliance. The case can be secured to the wall using four screws which are accessed via internal channels adjacent to the lid mounting SC screws. December 2008  67 OWOn HDS1022M-N Dual Channel Hand-held Oscilloscope Review by Mauro Grassi T he Owon HDS1022M-N is a portable, dual-channel digital oscilloscope that can double as a digital multimeter. It comes in a rugged orange and grey multimeter style case and has two BNC sockets for the connection of oscilloscope probes. It can run from its internal batteries for about four hours or from an external plugpack supply. This is not the only compact portable digital oscilloscope available but it is probably one of the most compact and attractive packages ever offered, considering its range of features and performance. The DMM is a practical add-on, allowing you to carry one less instrument in the field, as the Owon HDS1022M-N is primarily an oscilloscope. As a portable oscilloscope, it is well suited to most applications in the field, keeping in mind that its bandwidth is 20MHz when using a x10 probe (with a x1 probe, the bandwidth drops to 4MHz). 20MHz is enough bandwidth to di68  Silicon Chip agnose faulty composite video signals, for example. External connections On the front panel, the Owon scope has four 4mm banana sockets for connecting the multimeter leads: COM (ground), V/Ω/C (to measure voltage, resistance or capacitance) and two other sockets, one for DC and AC currents up to 400mA and the other for up to 10A. Above the DMM sockets is an array of pushbuttons which control the oscilloscope functions. It can be toggled between scope and DMM functions by the DMM/OSC button. The display simulates that of a centre-zero analog meter but also includes digital readout. You can use the automatic scaling mode or manually adjust the scale. You can also use a relative mode where you can set the ground reference to an arbitrary value. The oscilloscope inputs are on the side and are standard BNC types but without probe sensing. You can select the probe type (x1, x10, x100 & x1000) with the front panel buttons and the vertical sensitivity is adjusted accordingly. The unit is supplied with two x10 probes. Note that the multimeter and oscilloscope inputs are isolated from each other, meaning that you can have two different GND references. This helps to avoid unintended and possibly dangerous shorts, especially when switching back and forth between DMM and oscilloscope modes. The display The Owon HDS1022M-N has a 96mm (3.8-inch) colour LCD with QVGA (320x200) resolution. The screen can be used with or without backlighting and can be read in direct sunlight. The display can show 4096 colours and is a good size. You can see a typical screen grab in Fig.1. Persistence settings for the waveforms can be set from one second to five seconds and to infinite mode, a practical way to see quickly changing detail. You can also change the display siliconchip.com.au mode to use XY where channel 1 will correspond to the X (horizontal) coordinate while channel 2 will correspond to the Y (vertical) coordinate. The result will be a Lissajous figure. Quick setup As with most oscilloscopes, this one has an “AUTOSET” feature. When you press the AUTOSET button, the oscilloscope will display the waveforms, choosing the settings for the time base and vertical scale (among others) that give the optimal display. This makes it easy to get a signal on the screen. From there, you can manually adjust these settings as needed. Incorrect settings for the trigger level and trigger offset can give a poor, unstable display. With this oscilloscope you can always zero both of these (zero corresponds to the centre of the display) by pressing the V and R keys (normally used in DMM mode to select Voltage and Resistance measurements). Portable use car adaptor for use with 12V systems. Acquisition modes Specifications at a gla This oscilloscope supports up to three different acquisition modes. In standard mode, samples are acquired at equally spaced time intervals. This is a good general-purpose mode but you may miss fast glitches in the signal, which can be important if you are trying to diagnose faults. Alternatively, to better capture fast glitches in the signal, you can use the peak detect mode, whereby the oscilloscope will take only the maximum and minimum points in each time interval and display those. If the signal contains a high proportion of random noise, you can select the averaging mode. In this mode the oscilloscope averages out up to 128 sweeps of the waveform, effectively cancelling out the noise component. The internal 3500mAh 7.4V lithium ion battery will provide enough power for around four hours’ use when fully charged. Turning off the screen backlighting will improve the battery endurance substantially. However, you can use the plugpack to power the oscilloscope and charge the battery, when you have access to mains power. It takes about the same time again to fully charge the battery. It would also be useful to have an in- Triggering Fig.1: a sinusoidal waveform (red trace) at around 150Hz and amplitude 15V peak to peak. The second channel (blue trace) shows a pulse train at around the same frequency. The timebase is set for 2.5ms per division while the vertical scale stands at 5V/div for the red trace and 2V/div for the blue trace. The small coloured triangles to the left indicate the GND reference for each channel, while those to the right indicate the trigger level. Fig.2: two signals, one a sinusoidal waveform and the other a digital signal are shown on the same display, showing the use of the ALT (alternate) triggering mode. The frequency of the sinusoidal waveform is much greater than that of the digital waveform (as much as a hundred times). With the alternating trigger mode, we are still able to capture the edge of the low frequency signal. Without the alternating trigger, it would be impossible to make sense of the blue trace. siliconchip.com.au nce Input channels: ............ 2 Analog bandwidth: ..... .. DC to 20MHz (x10 pro be) Sampling rate: .............. 100MS/s Vertical sensitivity: ....... 5mV/div Vertical resolution: ....... 8 bits LCD panel: .................. . 94mm QVGA (320x20 0) Size (including case):.. .. 185h x 122w x 43d (m m) Net weight: .................. . 645g For triggering, the oscilloscope has AC or DC coupling and LF and HF rejection. It also has an unusual feature allowing you to change the so-called SENSITIVITY. This is a multiplicative factor between 0.2 and 1.0 applied to the trigger. It refers to the proportion of the current vertical division setting under which the trigger will be ignored and makes the oscilloscope more or less sensitive to triggering. This is useful for adding another layer of filtering and reducing the effects of unwanted noise. Edge and video triggering are available. In edge mode, triggering occurs when the signal contains a rising or falling edge passing through the trigger threshold, which is selectable. With video mode, both PAL and NTSC/SECAM are supported. A third triggering option is ALTERNATING. In this mode, you can select edge or video triggering for each channel. Triggering will then alternate between the chosen triggering options for channels 1 and 2. This is useful if you are viewing two substantially different signals simultaneously, such as two signals with markedly different frequencies, for example. The use of this mode is shown in Fig.2. Menu system The Menu System is composed of a vertical on-screen column of options (appearing and disappearing on the Fig.3: the measurements corresponding to the cycle RMS and frequency of the red trace can be seen in the top left corner of the screen. The measurement is applied to the sinusoidal wave shown as the red trace. Note that the background colour of the measurement window corresponds to the colour of the trace on the screen. In this case, they are both red as they correspond to the red trace. You can choose two on-screen measurements from either channel (red or blue). December 2008  69 Fig.4: the red trace is a sinusoidal waveform at around 150Hz while the blue trace is a pulse train at similar frequency. The green waveform is the result of the MATHs function that subtracts the value of the blue trace from the red trace in real time. The timebase stands at 5ms/div. Note that the vertical scales for the two input channels differ and are shown in the bottom left corner of the screen to be 10V/div for the red trace and 5V/div for the blue trace. Fig.5: this is the supplied PC software running on Windows XP. A sinusoidal wave is shown as well as the various menus. The PC software allows you to capture waveforms from the oscilloscope as well as to print them. The data is transferred either through a USB port or a serial port. You can also view the data table and export it to an Excel spreadsheet. Keep in mind that the PC software does not allow you to export bitmaps. To do that you can use a USB flash disk. right of the screen) comprising the main menu, as well as a horizontal row of options (appearing and disappearing from the bottom of the screen) showing the sub-menu options. The settings are changed using the five buttons immediately below the screen. There are two sets of three buttons for changing the vertical sensitivity of each channel, as well as a set of four arrow buttons having different functions depending on the context. The most common use for the horizontal pair of these is to change the timebase setting, while the vertical pair change the trigger level. The menu defaults and button functions are well chosen. As with any menu-defined keyboard it can be easy to lose your way when the definitions change. This oscilloscope shows the current definitions for the multiplexed buttons on the screen, which is helpful. Overall, the user interface is intuitive and should be easy to learn. Fig.6: the result of using the windowing feature is shown in this screen grab. This feature allows you to effectively zoom in on the two signals. The two signals are the same as those shown in Fig.1. You select the desired windowing by using the horizontal cursors, shown on the screen as dashed purple lines (not shown here). Once you select the windowing option, the time scale is modified so that the previously selected window now encompasses the entire display. measurements is limited, though, to just the following five: cycle RMS, mean, peak-peak, frequency and period. Because you can choose the channel for each measurement, you can have two of these measurements applied to the same channel. Keep in mind that two of the five measurements are really essentially the same; frequency is the reciprocal of period. You can, however, use the two cursors to measure other vital statistics of the signal. For example, you could use the cursors on a rising level of a waveform to measure its rise time (say between the 10% and 90% points). The supported MATHs functions include the four arithmetic operations. You can see the effect of adding, subtracting, multiplying and dividing the two signals as a third trace on the screen, in real time. Fig.4 shows the MATHs function in action. Quick measurements This oscilloscope allows you to show up to two measurements, superimposed on the display in the top left corner, as shown in Fig.3. You can choose the channel for each of the two measurements, as well as choosing what you A centre-zero multimeter in both analog and digital format? That’s just one of the modes/displays want to measure. The choice of possible with the Owon! 70  Silicon Chip Saving and transferring waveforms The oscilloscope allows you to save up to four waveforms to its internal nonvolatile memory. You can also use the small USB cable adaptor to connect a USB flash disk and save to that. This is an essential feature for any portable oscilsiliconchip.com.au The two scope inputs are on the lower right side of the meter, adjacent to the multimeter inputs. The remaining connectors lie along the top edge, above the screen. On the left is the DC power/charger input, with the COM, USB and HOST sockets alongside (left to right). loscope since you will be using it in the field and will likely find it convenient to save some of your work. Using the supplied PC software, you can then view the images on your PC. It lets you connect to the oscilloscope in real time, as well as viewing previously stored waveforms. As far as we can see, however, it does not let you export bitmap or GIF files (the version we tested was 6.8.01), although you can get around that by printing to files. The PC software does allow you to export the waveform data to a spreadsheet such as Excel. A screen grab from Windows XP is shown in Fig.5. Zooming functions The Owon HDS1022M-N oscilloscope has zooming functions. You set the width of the desired window by moving the cursors outwards from the centre of the screen. Then pressing the “Windowing” button adjusts the display to fit the selected area onto the entire display, as shown in Fig.6. We must stress though that these functions don’t enable you to see very fine detail, mainly because the resolution of the display as well as the memory depth (6Kpts) are somewhat limited. Conclusion The Owon HDS1022M-N is an affordable portable oscilloscope that is best suited for diagnosing video problems in the field, as well as for debugging most lower frequency circuits (up to 20MHz). It should be suitable for most audio work as well. The user interface is easy to learn and logical, with onscreen cues helping you at key moments. It is also nice that the cues disappear after a few seconds of inactivity, making the display less cluttered. The display is big but of relatively low resolution and it is easy to read, even without backlighting. The fact that it incorporates a DMM is a welcome addition. Both the scope and DMM inputs are rated at CAT II 400V maximum. The unit is supplied with two x10 oscilloscope probes and two DMM leads, as well as an aluminium carry case. The charger and PC software as well as a small cable to connect a USB device are also included in the price. The Owon HDS1022M-N retails for $1149.00 (inc. GST). For more details contact Owon Australia, Phone: 1300 792 976. Website: www.owon.com.au SC siliconchip.com.au December 2008  71 Any sensor that outputs a varying voltage can be used by the Simple Voltage Switch to turn things on and off . . . intercooler sprays, boost control solenoids, warning lights, fans, water injection – you name it! Design by JOHN CLARKE Simple Voltage Switch For Car Sensors This Simple Voltage Switch can be used anywhere you want a relay to switch when a voltage reaches a preset level. It has lots of applications in cars but can be used in any application where you have 12V DC available. Having switched the relay on, it will then switch if off as the voltage being monitored drops below the preset level. I N CAR APPLICATIONS, many engine sensors have variable voltage outputs and these can be used for relay switching. For example, if your car has an air-flow meter with a voltage output (most cars have), then you Main Features • Adjustable switching level between 0V and 16V at input • DPDT 5A relay • Configurable to switch on rising or falling voltage • Adjustable hysteresis • High input impedance – won’t load down sensors 72  Silicon Chip can use that as an engine load signal to switch things on and off. For example, do you want a warning when fuel usage is going through the roof, as it will be when the air-flow is high? If you use this project, it can turn on a light and/or sound a buzzer so you can ease off on the accelerator or change down a gear, or both. Or you could use the throttle position sensor directly, to do the same thing. Or going back to the air-flow sensor, in a turbocharged engine, you could use the Simple Voltage Switch to run a solenoid to close off the turbo waste from the boost pressure source whenever engine loads are low. Or maybe you could use the unit to control a water spray onto the intercooler. We are sure that you will be able to think of plenty of nifty ideas. This project was first presented in our “Performance Electronics for Cars” book published a few years ago and we are re-presenting it this issue to give it a wider exposure. It is quite simple in presentation; just a PC board with a relay and a handful of other components. You should be able to assemble it in less than one hour. Circuit description Fig.1 shows the circuit of the Simple Voltage Switch. It relies on comparator IC1a, which compares the input voltage to a preset reference level. The input voltage (VIN) is divided via two 1MΩ resistors in series which effectively apply one half of the voltsiliconchip.com.au Fig.3: the circuit is based on comparators IC1a & IC1b. IC1a compares the input voltage (VIN) to a reference voltage set by trimpot VR1 and switches its output (pin 1) high or low accordingly. IC1b acts as an inverter, while link LK1 allows the circuit to be set to trigger on either a rising voltage or a falling voltage. The selected comparator output drives transistor Q1 & the relay. age to the inverting input, pin 2, of IC1a. Zener diode ZD2 and the 100nF capacitor are there to protect against transient voltages on the input signal. IC1a’s non-inverting input (pin 3) is connected to reference trimpot VR1, via a 10kΩ resistor. When pin 2 is above pin 3, IC1a’s pin 1 output is low, ie, close to 0V. When pin 2 is below pin 3, pin 1 is high, at around +10V. Hysteresis (positive feedback from pin 1 to pin 3) has been added to prevent the output from oscillating at the trigger voltage. This is provided via trimpot VR2 and diode D3. This feedback causes the output to “pull” the voltage at pin 3 either higher or lower, depending on whether the output at pin 1 is high or low and also on the orientation of diode D3. If D3 is installed as shown (ie, anode to pin 3), the voltage on pin 3 will be pulled lower than the reference voltage set by VR1 when IC1a’s output (pin 1) goes low. However, if pin 1 is high, D3 will be reverse biased and the reference voltage is unaffected. siliconchip.com.au Conversely, if D3 is installed the other way around (cathode to pin 3), pin 3 will be pulled higher than the reference voltage if IC1a’s output goes high. In practice, this means that diode D3 is inserted with its anode towards pin 3 if you want the Simple Voltage Switch to trigger on a low to high (L\H) transition and with its cathode towards pin 3 if you want it to trigger on a high to low (H\L) transition. Basically, the hysteresis is the difference between the switch-on and switch-off voltages and this is set using VR2. We need hysteresis in the circuit otherwise the relay would tend to switch on and off very rapidly when Suggested Uses For the Voltage Switch • Intercooler water spray control (from air-flow meter, throttle position sensor or oxygen sensor signals) • Anti-lag turbo wastegate control (operating a wastegate disconnect solenoid triggered from the air-flow meter signal) • • • • Nitrous oxide switching (from throttle position sensor signal) Intercooler fan control (from air-flow meter signal) Dashboard monitoring LED (eg, oxygen sensor output signal) Switching in and out engine management and auto transmission control modifications (from air-flow meter, throttle position sensor or oxygen sensor signals) • Low battery voltage warning and/or disconnect December 2008  73 Parts List 1 PC board, code 05112081 or 05car061, 106 x 61mm 5 PC-mount 2-way screw terminals, 5mm pin spacing 1 12V PC-mount DPDT 5A relay (Relay1) 1 3-way header, 2.54mm spacing 1 jumper shunt, 2.54mm spacing 1 1kΩ multi-turn top adjust trimpot (VR1) 1 1MΩ horizontal trimpot (VR2) Semiconductors 1 LM358 dual op amp (IC1) 1 7808 3-terminal regulator (REG1) 1 BC337 NPN transistor (Q1) 1 5mm red LED (LED1) 2 16V 1W zener diodes (ZD1,ZD2) 2 1N4004 1A diodes (D1,D2) 1 1N4148 small signal diode (D3) Capacitors 2 100μF 16V PC electrolytic 2 10μF 16V PC electrolytic 1 100nF MKT polyester (code 104 or 100n) Resistors (0.25W, 1%) 2 1MΩ 1 1.8kΩ 1 22kΩ 1 1kΩ 4 10kΩ 1 10Ω the input voltage is close the to preset threshold. IC1b is an inverter and it provides a signal which is the opposite polarity to IC1a’s output. It compares IC1a’s output with the +5.5V set on its noninverting input. When IC1a’s output goes high, IC1b’s output goes low. And when IC1a’s output goes low, IC2a’s output goes high. Link LK1 provides the option of driving the relay with a falling (H/L) input voltage or a rising (L/H) input voltage, respectively. The output The Simple Voltage Switch could be used to monitor the oxygen sensor signal, allowing devices to be turned on or off when the mixture is too rich or too lean. The unit won’t load down the signal, so it can still be used by the ECU. selected (either from IC1a or IC1b) drives transistor Q1 which in turn drives the relay. The diode across the relay coil (D2) is there to quench the reverse voltage that is generated by the collapsing magnetic field of the relay coil when it is switched off. Without the diode, the relay could generate very high positive voltages which could blow the transistor. Power for the circuit is obtained from the switched +12V ignition supply. Diode D1 gives reverse connection protection, while the 10Ω resistor, 100µF capacitor and zener diode ZD1 provide transient protection at the input of regulator REG1. The reference circuitry is powered from the output of REG1 (+8V), while the remainder of the circuit is powered from the +11.4V rails which are derived before the regulator. Construction While the unit is simple to build, Resistor Colour Codes Value 4-Band Code (1%) 5-Band Code (1%) 1MΩ 22kΩ 10kΩ 1.8kΩ 1kΩ 10Ω brown black green brown red red orange brown brown black orange brown brown grey red brown brown black red brown brown black black brown brown black black yellow brown red red black red brown brown black black red brown brown grey black brown brown brown black black brown brown brown black black gold brown 74  Silicon Chip you need to know one thing about its eventual application. Will you be using it to detect a voltage that will be increasing (L/H) to the preset trip point or falling (H/L) to the preset trip point? The unit can be made to work either way but if you know this before you assemble it, there will be no need to make changes when it is ultimately installed. The low to high (L/H) voltage condition will be the most common, as in our example of switching an intercooler spray when the air-flow signal rises above a particular point, say 4V. Below 4V, the spray is off and above 4V, the spray comes on. So ideally, you need to know which configuration you want before starting assembly. That way, you will know how to set the position of the link on the board and the orientation of diode D3. On the other hand, if you do build and later decide to change the application, it is a simple matter of changing the link setting and the orientation of D3. So for a rising voltage detection, the moveable link LK1 is placed in the “L/H” position, as shown in the component overlay diagram of Fig.2. Then diode D3 is orientated so that its cathode band is closest to the top of the board. For the opposite condition, detection of a falling voltage, the link is moved to its “H/L” position and the diode’s orientation is reversed. When assembling the PC board we siliconchip.com.au D1 1N4004 + 100 µF 10 µF 1k + L/H LK1H/L L/ H Q1 + CN NC } } RELAY CONTACTS 1 6 0ra c 5 0 1 CN 22k C COM A The placement of the link and the orientation of diode D3 (both circled here) will depend on whether you want to activate the switch on a rising voltage or a falling voltage. As shown here, the unit is configured to trigger on a rising voltage, which is the most common requirement. To trigger on a falling voltage, reverse the orientation of diode D3 and move the link to the H/L position. ON NO 100 µF H/L K 10k 1M 100nF ZD2 niV Vin COM NC 1 10 µF 1M K 1M NO RELAY CONTACTS 2 A LED1 IC1 LM358 + 1N 4148 ZD1 A K 10k K 10k GND D3* MAX 10k REG1 7808 VR2 1.8k MIN K D2 1N4004 10Ω +12V A VR1 1k C ON H CTI WS E GATL OV K 1N4148 A RELAY 1 A BC337 * REVERSE D3 IF LK1 IS IN 'H/L' POSITION Fig.1: install the parts on the PC board as shown on this layout diagram. Don’t forget to reverse D3 if LK1 is placed in the H/L position, ie, if you want the unit to trigger on a falling voltage instead of a rising voltage. suggest that you start with the resistors and diodes and then progress to the larger components. Carefully check each component value before you install it and make sure that you insert the polarised components (diodes, IC, LED, transistor, voltage regulator and electrolytic capacitors) with the correct polarity. Testing it Test the kit at your workbench (or kitchen table) to make sure that it is working, as it should. Do not be tempted to install it straight into your car or other application before you know that it is definitely working properly. You will need a 12V battery or DC power supply and a variable voltage, to simulate the sensor output that the unit will be monitoring. The easiest way to do this is as is shown in the photo on page 76 – it’s just a matter of connecting a pot (eg, 10kΩ or more) across the supply, to give a 0-12V variable voltage at the wiper terminal. Connect the DC supply and a potentiometer, as shown in the photo. Now rotate the potentiometer back to forth over its full range. At some point as you are rotating the potentiometer, the relay should click and LED1 should turn on or off. Rotating the potentiometer back the other way should again make the relay click and switch LED1 back off. siliconchip.com.au Fig.2: here is a typical set-up. The Simple Voltage Switch is connected to an ignition-switched +12V supply rail and to chassis, while the signal input is wired to the air-flow meter’s output signal. One of the relay’s normally open (NO) connections is also connected to the ignitionswitched +12V rail, while the adjacent common terminal is connected to an intercooler water spray pump. The other side of the pump is earthed. When the engine load exceeds a preset level, the water spray will be triggered into action. This view shows the fully-assembled PC board. Make sure that you install the polarised components the correct way around. December 2008  75 An easy way to bench test the Simple Voltage Switch is to temporarily wire a 10kΩ (or higher) pot across the power supply to provide a variable signal voltage. An adjustable 0-12V will be available on the centre terminal of the pot. Here, the blue wire connects this variable voltage to the signal input of the Simple Voltage Switch. Connect the +12V and earth terminals to the red and black wires respectively and you can easily test the operation of the device. Using a multimeter, measure the voltage at the signal input (ie, connect the positive probe of the multimeter to the signal wire and the negative probe to earth) and measure the voltage at which the unit is activating the relay. For example, with the unit arranged to read rising voltages, as you gradually raise the input voltage the unit might turn on at 6.00V. Now very slowly reduce the voltage to see at what point the relay turns off. You might find that the latter voltage is 5.7V, meaning that the hysteresis (the difference between the switchon and switch-off voltages) is 0.3V. Rotate VR2, the hysteresis pot, to make sure that the hysteresis changes. For example, with a switch-on voltage of 5.00V the switch-off voltage might now be only 4.96V; but a hysteresis of just 0.04V is making it too critical! As you rotate VR2 clockwise, the hysteresis will increase. Note that changing the hysteresis will not change the trip point, allowing the two to be set individually. Next, you can test VR1, which sets the trip point. As you turn VR1 clockwise, the trip voltage will increase. VR1 is a multi-turn trimpot, so that the trip point can be set very precisely. Note that you can keep on turning this type of trimpot endlessly and never reach a clear “stop”. Installation Fitting the unit to a car is straightforward. You will need to provide an ignition-switched +12V supply, earth (chassis) and the connection to the 76  Silicon Chip sensor signal you want to monitor. For example, if you are triggering the unit from the air-flow meter, you’ll need to use the workshop manual and a multimeter to find this wire. You will need to confirm that it has a voltage on it that rises with engine load and you will need to drive the car to do this. The device to be switched by the relay will be connected to the Normally Open and Common relay contacts. Fig.2 shows these connections. Note that because a double-pole, double-throw (DPDT) relay has been used, another independent circuit can be switched simultaneously. This other circuit can even turn off the second device as the first is switched on. If you want to simply monitor a voltage such as that from the oxygen sensor, you can delete the relay and mount the LED on the dashboard. In this way, the LED will come on when the fuel mixture is rich, flash when the mixture is oscillating in closed loop mode, and turn off when the mixture is lean. Setting it up There are two ways of setting up the Simple Voltage Switch: (1) Measure the sensor voltage and then set up the unit on the bench to operate at this voltage. This will probably avoid any need for fine-tuning in the car. (2) Do the complete set-up on the car itself. If you are using an oxygen sensor to trip the unit, then the first way is better. For example, if you want the unit to trip when the sensor signal rises above 0.6V, then set it up on the bench to do this. When you subsequently install the unit in the car, you will only need to make a small adjustment to VR1. However, if you want to turn on a device when monitoring the air-flow meter, it’s best to do it on the car, because the air-flow meter signal varies over a much wider range. When setting up, set the hysteresis pot to its minimum setting (ie, fully anticlockwise) and then adjust the trip point until the unit triggers when you want it to. If the relay tends to chatter around the trip point, rotate VR2 clockwise to increase the hysteresis. When it is tripping at the correct voltage, check how long the device continues to operate as the voltage again drops (assuming the unit is set to trip on a rising voltage). For example, if you are using the unit to trip an intercooler water spray on the basis of air-flow output, does the spray go off fairly quickly as the load again drops? In some applications, the hysteresis setting will be critical while in other applications it won’t matter much at all. In most cases, once the unit has been set up, it won’t need to be altered. The PC board fits into a standard 130 x 68 x 42mm jiffy box, so when the system is working correctly the board can be fitted into the box and installed under the dash or wherever SC it is convenient. Footnote: a kit for this project is available from Jaycar Electronics, Cat. 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PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. ALL PRICES INCLUDE GST OR PHONE – (9-5, Mon-Fri) This form to PO Box 139 Collaroy NSW 2097 Call (02) 9939 3295 with your credit card details December 2008  77 12/08 The 2008 AEVA Electric Vehicle Field Day by Leo Simpson T his year’s field day for the Australian Electrical Vehicle Association, held at Annagrove in western Sydney during late October, had a range of interesting electric and hybrid electric vehicles on show. Some were fully converted cars that are driven on a regular basis while others were “works in progress” which may be up to a year or more away from completion. There was also a Toyota Prius which had been modified with extra battery capacity and an on-board charger. At the outset it must be said that anyone who decides to convert any conventional vehicle to electric drive is taking on an ambitious project. Typically, the way they go about it has never been done before: to convert exactly that vehicle type or model, using that combination of motor, batteries, controller etc. So the AEVA annual field day is very much a display of DIY electric 78  Silicon Chip The AEVA field day at Annangrove was pretty basic in format – just a big open shed with lots of electric car enthusiasts poring over the cars. There was even an electric go-kart – with neck-snapping acceleration! siliconchip.com.au (Opposite): star of the show, Carmel Morris with her Mitsubishi Starion conversion, also shown above. It uses an array of lithium iron phosphate batteries in the boot and bonnet compartments. The DC motor is run by a Curtis controller. The sheet of Lexan over the engine compartment is to prevent any of the viewers touching the battery array – it could be quite lethal! vehicle conversions rather than an expo of the latest up-tothe-minute technology. And no doubt, all the owners would go about such a conversion quite differently if they were going to repeat the process – such is the value of on-the-job experience. As far as we could tell, all the electric conversions on display used DC motors with wound fields and they ranged in power up to about 70kW. Such a power rating may not sound numerically impressive compared with typical petrol motors which can be up to 200kW or more. But whereas the 200kW rating for a petrol motor is an absolute maximum rating which is rarely, if ever, likely to be delivered (or even available at the wheels), a 70kW motor is quite likely to be able to deliver three times the continuous power for short periods. As well, electric motors deliver close to their maximum torque at very low revs, so an apparently modestly-powered motor can give quite sparkling acceleration. Most, if not all the electric conversions on display used one or another model of motor controller made by the US company Curtis. These essentially have a bank of power Mosfets operated in PWM (pulse width modulation) mode This 2002 Holden XC Combo van had the usual DC motor and Curtis controller and was powered with 16kWh’s worth of Trojan wet cells. They occupy a fair amount of the cargo space, as shown in the photo below. It is used for daily commuting of about 35km each way and takes about 4.5 hours to recharge after each trip. There was even a VW Beetle EV conversion. There are more batteries inside the (front) boot, as well as those on view in this photo. While the batteries take up a lot of space in the Combo van, the all-up weight is not excessive at 1540kg. Best feature according to the owner is the electric power steering. siliconchip.com.au December 2008  79 Extra batteries added to this Toyota Prius give it an estimated electric-only drive range of 40km. The 256V battery pack is in the same voltage range as the existing battery and is disconnected by a big contactor (visible at one side of the boot) for charging via the 240VAC socket on the rear bumper bar. We liked the solid mounting for the batteries – you would not want them coming adrift in accident. Maximum measured fuel consumption for the Prius above in mixed petrol/electric mode is 2.3l/100km. That’s 122 MPG! Oops, did we mention MPG again? Silly us! under the control of a microcontroller. In every case, the cars had a throttle control potentiometer for speed control. None appeared to make use of regeneration under braking and all used some variant of lead-acid or lithium-iron phosphate batteries. Some motors were wired in series mode (ie, with armature and field windings in series) while others were wired in shunt mode with the field windings run at constant voltage while the armature voltage was varied (using pulse-width modulation). All on-road conversions need to pass inspection by the transport authority in the relevant state and these have comprehensive specifications which must be met before the vehicle can be passed. Electrical safety is most important, both from the aspect of avoiding electric shock as well as potential fire hazards if, for example, high voltage battery banks are shorted in an accident. Each of the cars on display had varying approaches to safely securing the batteries and they all had heavy-duty contactors to disconnect batteries when not in use. Providing heating is a problem when there is no waste heat from an internal combustion motor available. The common approach seems to be to use a hair-dryer running from the main battery bank. In a similar vein, power brakes must still be available and This Datsun 1200 EV conversion had a large array of batteries underneath the fibreglass canopy. Note the extra lead-acid battery in the engine compartment; necessary to run headlights and all the accessories. All EV conversions need a separate 12V battery or a step-down DC-DC converter, for this reason. 80  Silicon Chip siliconchip.com.au This Mitsubishi Triton EV conversion was perhaps the most impressive on display with a whopping DC motor. However, the rear ute section was chock-a-block with batteries, leaving little capacity to carry extra load. Again note the 12V battery in the engine compartment for lighting and accessories. a 12V vacuum pump connected to the original accumulator is the common approach. Some conversions are now using electric power steering, adapted from cars like the Honda Jazz. We did not see any cars with LEDs for stop/tail or traffic indicators – a little surprising perhaps. Our overall reaction? We salute those people who take on such a project. In each case it must be a very good learning experience with a great sense of accomplishment when it is finished. For more information, go to www.aeva.asn.au A video of AEVA field day is presently available at www.electriccarsforeveryone.com/blog/ SC This mini was an intriguing conversion with not a lot of installed batteries. The east-west DC motor is well hidden from view. Making a return appearance from previous years was this 1987 Toyota Camry station wagon. As the data sheet above shows, the Camry employs the standard 5-speed gearbox but no clutch is required. The large battery load means that it can only carry two people. siliconchip.com.au December 2008  81 Vintage Radio By RODNEY CHAMPNESS, VK3UG The Leak TL/12 Plus Valve Amplifier British manufacturers built some superb high-end audio amplifiers during the 1950s and 1960s and the Leak TL/12 was one of these. It’s a 5-valve mono amplifier with some interesting design features and is reasonably easy to service. This view shows the fully restored audio amplifier. Note the new capacitor can at the back, between the two transformers. 82  Silicon Chip I F WE LOOK AT the circuits of early 1920s receivers we see that triodes were used to amplify the audio signals, with 1:3 to 1:5 audio step-up transformers between each stage. The triode output stage was then coupled to an output transformer which in turn fed the loudspeaker. In cheaper receivers, the limited output from the triode output stage often fed a high-efficiency, high-impedance horn speaker. These speakers looked beautiful but the audio quality left a lot to be desired. Certainly until well into the 1930s, the audio reproduction that was obtained could hardly be called “high fidelity” (or hifi). Even in 1935, “Modern Radio Servicing” by Alfred Ghirardi quoted high fidelity as the reproduction of the frequency range from 50 to 7500 cycles at 5% distortion. That’s truly dreadful by today’s standards. A typical “high-fidelity” amplifier of the 1930s still used triodes in all amplifying stages plus an output transformer. The output transformer matched the high impedance of the triode push-pull output stage to a level suitable for the speaker(s). In addition, some amplifiers also included a pushpull audio driver transformer to act as a phase splitter and driver to the triode output stages. Even when tetrode and pentode output valves became common, the highest quality audio was still obtained from triodes. Negative feedback also became common during the 1930s. This involved taking a proportion of the output from the secondary of the audio output transformer and feeding it back in anti-phase to an earlier stage in the amplifier. This negative feedback reduced the gain of the amplifier at all frequencies but more so at the frequencies that had the greatest amplification. This smoothed out the gain across the audio band and reduced distortion. It did, however, mean that such amplifiers siliconchip.com.au Fig.1: the Leak TL/12 Plus is a 5-valve mono amplifier. V1 functions as an input/preamp stage, while V2 is wired as a phase splitter. The latter drives V3 & V4 which, together with transformer T1, operate as a push-pull output stage. usually required an extra stage to make up for the lost gain due to negative feedback. Even so, the advantages of negative feedback made it well worth having. As time went by, manufacturers became increasingly keen to use tetrodes and pentodes in the output stages of audio amplifiers, as they had higher gain than triodes and were more efficient. However, the audio quality of early amplifiers using these valves was not as good as those using triodes. Subsequently, in the 1950s and 1960s, a modified audio output stage was developed that had high gain and efficiency but also relatively low distortion levels. This amplifier circuit configuration was called “ultra-linear” and it used tetrodes or pentodes in a semi-triode type circuit. In the ultra-linear circuit, the valve screens were connected to taps part way along the audio output transformer. This became a very popular method siliconchip.com.au of obtaining good-quality audio output while relying on the added efficiency of tetrode and pentode valves. In fact, the Leak amplifier featured here uses an ultra-linear output stage. disagree with me and tell me that valve amplifiers have qualities that make them better than solid-state equivalents. That of course is a personal view but not one with which I concur. The weak link The Leak TL/12 Plus amplifier The audio output transformers were (and still are) the weak link in valve amplifiers, particularly when it comes to producing high-quality audio over an extended frequency range. In fact, good-quality transformers are specially wound to ensure a good frequency response and to reduce spurious resonances. By the 1960s, valve hifi amplifiers had come a long way and the Leak described in this article was one of the best. After that, transistor and FET audio amplifiers quickly outstripped valve amplifiers in audio quality, total audio output, distortion figures and total efficiency. Of course, some audiophiles will The Leak amplifier featured here was given to me some time ago. Unfortunately, though, it didn’t come with its preamplifier or the perforated metal cover which fits over the top of the chassis. This particular unit had been pulled out of the PA system in a local church after many years of faithful service. It is not a particularly powerful amplifier but is typical of the high-end 10-12W amplifiers that were developed in the early 1960s. When I first got the amplifier, it was immediately obvious that a few rather odd alterations had been done to it. It was certainly not the standard of work you would expect on a high-quality December 2008  83 This is the Leak amplifier before restoration. The original capacitor can had been removed and replacement capacitors fitted under the chassis. piece of equipment. For example, the main supply electrolytic capacitors had been replaced but instead of being fitted into a can above the chassis, had been attached to the underside of the chassis with silicone sealant. However, since the repair, they had subsequently parted company with the chassis, so that they were just floating on their leads. They looked terrible and would have still looked terrible even if the silicone had held fast. Other electrolytic capacitors looked as though they had just been “thrown in” too, in various other parts of the amplifier. In fact, it looked like all the electrolytic and paper capacitors had been replaced. My first step was to replace all the high-voltage electrolytic capacitors with more suitable values and voltage ratings. At the same time, I made sure that these were installed in a much more professional fashion. It’s worth noting that the ones I removed didn’t suit the amplifier, although they were still working OK. For example, C13 and C14 (the main supply filter capacitors) were both 100μF capacitors instead of 32μF, as specified on the circuit. In particular, C14 should not have been increased to 100μF as the peak charging current through rectifier valve V5 would have exceeded its rating and shortened the life of the valve. In addition, someone had modified the input circuit, probably to cater for a transistor preamplifier. The additional The replacement capacitors had been secured with silicone sealant but this had since parted company with the chassis. 84  Silicon Chip parts were removed and the audio input stage restored to its standard configuration. Next, I decided to improvise a chassis-mount can to house the fresh 32μF capacitors (C13 & C14). A small can of mushrooms was just the right size for this job. Having consumed the mushrooms and cleaned the tin, I soldered two solder lugs to it at the open end, so that I could later bolt it down to the chassis. The can was then sprayed with matt black spray paint to match the rest of the amplifier. While the paint was drying, I check­ ed all the resistors in the amplifier. A number of these were considerably out of tolerance and so were replaced. These components are all mounted on a large tag strip and are quite easy to get at. However, for some strange reason, many of the components are not grouped close to the valve stage that they attach to. Next, I cut a small section of perforated board to mount underneath the chassis, directly below where the capacitor can would sit. The new electrolytic capacitors were then installed inside the can and held in place with contact adhesive, foam plastic sheet and electrical insulation tape. That done, I mounted the new can, complete with the capacitors, onto the chassis and wired the components into circuit via the perforated board (see photo). The top of the chassis now looks almost the same is it did when the amplifier was new. Circuit details Fig.1 shows the circuit details of the Leak TL/12 Plus. It’s quite conventional and so most faults would be easy to find. The first stage is an EF86 (V1), which is a low-noise audio pentode. It receives its signal via the “preamp” socket which is located on top of the chassis. R2 is included prevent RF signals from causing problems in the stage. The cathode circuit and the plate circuit both deserve some comment. As shown in Fig.1, the feedback signal from the output transformer is applied to the cathode circuit by connecting it across a 100Ω resistor and a 1nF capacitor. The latter tailors the feedback signal to correct any phase problems. siliconchip.com.au Capacitor C15 and resistor R23 in the plate circuit are included to give a small amount of top cut into the supersonic region. V1’s output is applied via capacitor C4 to the grid of the first triode in V2. This valve is a twin triode 12AT7 and it functions here as a phase splitter. Because there is no bypass capacitor across resistor R10, the cathode of the first triode tends to follow the voltage fluctuations on the grid due to the input signal. In addition, because the two triodes in V2 have their cathodes commoned, the cathode of the second section is forced to follow the cathode voltage of the first section. However, the grid of the second triode is effectively earthed as far as the signal is concerned by capacitor C9. This means that if the first triode has a positive-going signal applied to its grid, it will draw more plate current as the cathode tries to follow it in a positive direction. As a result, the plate voltage will drop because of the increased voltage across R9 (due to the increased plate current). This in turn means that a negativegoing signal is fed via C8 & R21 to the grid V3 (EL84). At the same time, the cathode in the second section of V2 also swings in a positive direction. However, the grid voltage is maintained at its original level, so more negative bias is applied to this section. In this situation, this valve section moves towards cut-off and so the voltage on its plate rises. As a result, a positive-going signal is applied to the grid of V4 (via C10 & R18). This means that a push-pull signal is effectively applied to the two output stage grids. Push-pull output stage V3 and V4 (EL84s or 6BQ5s) are connected into the circuit as push-pull amplifiers in the ultra-linear mode. Conventional PA amplifiers would have the screens of these valves wired to pin 7 of the output transformer whereas in the ultra-linear mode, they are wired to pins 4 & 5 respectively. Note that the output transformer has tappings on its secondary for 4, 8 and 16-ohm loudspeaker systems. The negative feedback line is taken from the 16-ohm terminal of the output transformer and applied via R12 and C7 to the cathode circuit of V1, as mentioned previously. siliconchip.com.au This under-chassis view shows the amplifier before restoration. Note how the replacement electrolytic capacitors at the bottom had come adrift, giving an untidy appearance. The parts on the tag board are easy to replace. The EL84s (or 6BQ5s) operate most of the time as push-pull class A amplifier stages but operate in class AB1 at high volume. One point to note is that, throughout the amplifier, the plate to grid coupling capacitors have larger values than those found in valve radios. This is so that audio frequencies down to about 20Hz can be reproduced. In domestic radios, the audio response rarely extends below around 150Hz. Basically, there was no point in extending the response lower than this because the modest speakers fitted to mantel receivers have very little baffling and do not work well below that frequency. In fact, this was rather convenient as it meant that the designers and manufacturers could restrict the frequency The things people do – cutting the earth lead to a mains plug is never a good idea! response of the amplifier and eliminate any hum problems that might otherwise be present. This also kept the manufacturing costs down. Power supply The power supply is conventional and uses a 5V4G indirectly heated rectifier valve (V5). This produces the high-tension (HT) supply for the valve plates and screens. The advantage of using an indirectly heated rectifier is that it begins operating at about the same time as the other valves. This means that the peak output voltage on the filter capacitors is almost the same as the working voltage and so lower rated capacitors can be used. Filtering and decoupling on the HT line is extensive, with R7, R15 & R22 doing the decoupling and C5, C6, C13 & C14 doing the filtering. The 6.3V AC heater output from the mains transformer is centre-tapped, with the centre tap going to earth. This helps cancel out any induced hum from the heaters into other valve elements. Several years ago, I had cause to service a Geloso amplifier with similar output power to the Leak. It was a PA amplifier but had some interesting features in the power supply. There was a winding on the power supply that gave a voltage rail of 25V when rectified. December 2008  85 An under-chassis view of the restored amplifier. A small piece of perforated board was used to terminate the leads from the new electrolytic capacitors fitted into the replacement can. This supply had its positive side earthed and it provided bias for the 6BQ5 valves via a potentiometer. This DC voltage also fed the heaters of two 12AX7 valves in the early stages and it very effectively overcame any problems of hum leakage in the lowlevel sections of the amplifier. It was a nifty idea that wasn’t copied by many manufacturers. Testing Before going for the smoke test, I carefully checked all the wiring, terminals and components and all looked to be in order – with one critical exception. When I checked the wiring to the power plug, I found that there was no continuity between its earth pin and the chassis. A quick check at the amplifier end showed that the earth lead was securely attached to the chassis so I removed the cover from the 3-pin mains plug. And that revealed the problem – as shown in one of the photos, the earth lead had been cut off. Of course, it couldn’t be left like that, since that would leave the chassis without an earth which would be dangerous. Cutting the end off the mains cable and re-attaching the plug quickly solved that problem. So why had the earth lead been cut 86  Silicon Chip off? This was not uncommon in the 1950s and 1960s when “earth loops” or “hum loops” were encountered in audio amplifier installations. Typically, there would be a turntable, a reelto-reel (or cassette) tape recorder and an AM radio tuner all attached to the amplifier. These items would all have separate earths and circulating earth currents could find their way into the sensitive input stages via the shielded connecting cables. As a result, these mains frequency signals would then be amplified and would appear as a loud hum. One of the methods used to overcome this problem was to remove the mains earth connection on one or more pieces of equipment – a quite illegal and potentially dangerous practice. A far better method was to use 1:1 audio transformers. These isolated the signal earth of each piece of equipment and hence interrupted the earth or hum loop. Getting back to the Leak amplifier, with the valves installed and the power turned on the voltages rose to about what would be expected. I then checked the power consumption and it was 58W which again is about what was expected. The amplifier was also completely quiet with no hum or buzzing noises but when a finger was placed on the input a healthy “blurt” of hum was heard from the loudspeaker. The amplifier was working. I don’t normally do any tests on the audio amplifiers in domestic radios unless the sound quality is unpleasant. In this case, however, I decided to do some tests to see how well this amplifier performed and to see if I could spot any performance problems. I began by connecting my audio oscillator to the input, then connected a good-quality 8-ohm loudspeaker and an oscilloscope across the output terminals. That done, I varied the oscillator frequency from 20Hz to 24kHz and found that the response was substantially flat from around 20Hz to 12kHz. It dropped off after 12kHz but there was still substantial output at 24kHz, as observed on the oscilloscope. There were no signs of supersonic oscillation on the oscilloscope pattern, which indicated that the amplifier was stable. In addition, as the input signal was increased, the amplifier clipped symmetrically on the negative and positive excursions of the waveform. Next, I connected an 8-ohm load resistor and checked the output level just before distortion became observable. This gave a power output of 10W RMS, which again is about what I expected. New output valves may give slightly more output but there are probably many more hours of life left in the existing valves, so there was little point in replacing them. So, despite its age, the Leak TL/12 was still giving good performance. Summary This Leak amplifier is a good performer and is reasonably easy to service. However, some of the components on the tag board are a bit remote from their associated valve stage, which means that identifying a particular part can sometimes require a bit of circuit tracing. Fortunately, the parts are easy to get at and the component board is not mounted over the top of the valve sockets, as was done in the “Pee Wee” receiver described in the September 2008 issue. In summary, it is a great little amplifier and well worthwhile having in a collection. It’s just a pity that it didn’t come complete with the preamplifier SC and its chassis cover. siliconchip.com.au 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 silicon<at>siliconchip.com.au Adding FM reception to an AM radio I have an old AM valve radio. Is there an FM radio kit that could be used to add FM reception to the amplifier stage with a separate tuner? (G. K., via email). • It is a problem isn’t it? Old valve radios look great but they don’t get FM. At present the only remedy is to modify a small AM/FM radio and feed the FM output to the amplifier stage in your radio. There is no kit to do the job. If you want listen to CDs, etc on your radio, why not consider building the Little Jim AM Radio Transmitter described in the January 2006 issue. Mosfets for TENS unit I’m trying to build the Pocket TENS Unit featured in the January 2006 issue. I am having trouble locating the STP6N60E N-channel Mosfets or similar devices, rated at 200V 1A minimum (Q1, Q2). Could you perhaps suggest a different part number? (M. C., via email). • You can substitute the low-cost STP4NK50ZD or STF4NK50ZD Mosfets. These are rated at 500V and 3A. You can obtain them from Farnell – see www.farnellinone.com.au or phone 1300 361 005. Their catalog numbers are 129-1984 and 129-1974 respectively. HDTV sound level is louder than SD I recently purchased an LCD HDTV and when I change from a standard definition broadcast to a high definition broadcast I notice that there is an increase in sound volume. I believe this is because of the different audio system used in HD broadcasting. I have the audio output of the TV going into my stereo system and I find that I am constantly reaching for the stereo system remote control to adjust the sound down to a comfortable level again. This gets a bit annoying after awhile. My question is has SILICON CHIP ever thought of publishing a project for a circuit that could be plugged in between the audio output of the TV and the input of the stereo system that would keep the audio at a preset level? This device could also be useful for those commercials that seem to be very loud also. (B. A., Hobart, Tas). • Normally, there should not be any change in sound levels when switching from SD to HDTV broadcasts and we would be inclined to check the settings on your TV. Be that as it may, you could use a compressor to solve the problem but it does seem like a lot of trouble given that a press of a button on the remote fixes it. We published a stereo compressor in the June 2000 issue and while it is no longer available as a kit, all the components should still be available. The key SSM2018P chip (two required) can be obtained from Farnell Electronic Components – www.farnellinone.com.au Interval timer questions I recently bought one of the new PICbased Mk4 Flexitimers (SILICON CHIP, August 2008). I want the timer to run a water to air intercooler pump and fan for a couple of minutes after being triggered by an RPM switch output from an aftermarket engine computer. However, from my interpretation of the article, the Flexitimer microcontroller needs to be manually reset after each timing cycle. FM Micromitter Does Not Have Volume Compression I have purchased the Jaycar version of your Stereo FM Micromitter, featured in the December 2002 issue. Whilst I had no troubles with the construction and set-up, I have a question regarding the audio level on my stereo system, when compared to commercial FM stations. I am driving the Micromitter with the audio line from my PC and with the audio line level set to maximum and VR1 & VR2 set fully clockwise. However, there is still a significant difference in the audio level when I then switch the stereo system to a commercial FM station. siliconchip.com.au Is this just a feature of the Micromitter that one just has to get used to or does it indicate a fault? TP1 is at 2.2V and VR3 was set to 1/8 of total adjustment after the stereo indicator came on. I am also powering it from a plugpack and the +5V rail is spot on. Otherwise I am very pleased with the performance. (L. C., Moggill, Vic). • Most commercial FM stations apply considerable signal processing to compress the audio so that there is limited dynamic range. This makes the signal effectively much louder – which is what the commercial stations want. However, this compression also helps when listening in a car as quiet passages are boosted in level. You should be able to verify this by tuning to the ABC FM stations when they are playing classical music. You will clearly hear the difference since these transmissions are not compressed – in other words, the quiet passages are quiet and the loud passages are loud. The FM Micromitter does not compress the signal and this is why it appears to be lower in volume than commercial FM stations. December 2008  87 Inverter-Driven Induction Motors I refer to page 5 of the July 2008 issue, where you wrote: “In fact, using transistors for such simple commutation [induction motors] is never done, as far as we know”. I believe there is a most important application for inverters driving induction motors. My belief is based on logical reasoning drawing on non-technical information. I would indeed be most grateful if any reader can confirm or deny my assumption. I believe inverter-driven induction motors are used extensively as traction motors in railway locomotives, as an alternative to the DC traction motor which has been with us in various forms for over a century and is still preferred by many railways. My reasoning is based on the observation that a locomotive wheel set need not and should not be driven at a precise constant speed, as it would be if a synchronous motor were used. Since wheels wear, no two wheels in a locomotive will end up the same size after some use. Often, they won’t even be round (thump, thump). Even the wheels on a given wheel set will try to turn at different speeds, especially on curves. Suppose the maximum frequency of the inverter is 50Hz then, I surmise, the inverter frequency drops to a low value, say 5Hz, for starting, with the inverter at all times limiting the current. I also suspect that some of these things are proprietary infor- It seems counter intuitive that this is the case but the one-shot mode also kind of sounds like the timer is only good for one timing cycle between resets. Can you tell me if the timer kit will be suitable for what I want to do? (M. L., via email). • From your description of your intended application, it sounds as if the Flexitimer Mk4 should be suitable. You’d use it in one-shot mode and trigger it via a normally-open contact set from the engine computer – connected to the circuit instead of S1 (or just in parallel with it). Each time it is triggered, it will switch on its own relay for the programmed time period and 88  Silicon Chip mation, especially the algorithms designed to reduce wheel slip. Therefore, it is necessary to cut the motor some slack and this is provided by the induction motor slip. Any comments please? Am I right or wrong? (J. W., via email). • All modern electric locomotives use induction motors driven with a variable-frequency variable-voltage inverter providing 3-phase drive, very similar in principle to that used in the Vectrix motorbike featured in the May 2008 issue. Of course, the inverter does not use simple transistors but large banks of IGBTs (insulated gate bipolar transistors) to provide the high voltages and currents. Individual wheel slip is not a major problem in a 2-axle or 3-axle bogie as the induction motors tend to be locked together in synchronism with the drive voltage, although there will be the normal slip factor of induction motors. Wheel slip of the entire bogie is often controlled by a radar feedback system which ensures that axle speed cannot exceed an appropriate value relative to the track speed. We have had articles on this subject in the past. In fact, these days, all large AC motor drives are based on induction motors with variable-frequency variable-voltage inverters. The SILICON CHIP bookshop sells a number of books on electric motors and drives. then turn off again until it’s triggered on next time. Setting up the Fuel Mixture Display I purchased a kit for the Fuel Mixture Display (SILICON CHIP, September & October 2000). I have had a lot of experience in electronics and have checked and rechecked the board for faults but I cannot get the readout to zero via the offset pot VR3, as per your instructions. It seems that the divider network to pin 3 of IC2a should be a 10kΩ resistor and not a 100kΩ resistor from pin 3 of IC1a to VR3, because the readout does not go lower than 1.42V when VR3 is set to full short. It seems that the SPAN VR2 network may be at fault. Any ideas? (R. L., via email). • The span set-up does work provided that you get -2.49V at the anode of REF1 and that all the component values for the resistors are correct. Note that VR1, VR2 and VR3 all have different values and each must be installed in its correct position. In particular, VR3 must be the 20kΩ (code 203) unit. Also, you should ensure that Q6 is a BC337 and that diodes D1 and D2 are orientated correctly. Questions on the multimessage recorder I am working on a HSC Design and Technology project which incorporates the Multi-Message Voice Recorder. I was wondering about the size and type of amplified speaker. Will the device carry six different tracks of 30 seconds each? I would also like to have a button for each track and am unsure on how to do this. (M. W., via email). • The size of speaker used is quite flexible and it’s a matter of “the larger the better” because larger speakers tend to be more efficient. But please note that if you are talking about the recent design as published in the December 2007 issue, you’ll also need a small amplifier to drive the speaker. The total message length able to be stored in the HK828 device is about 45 seconds, depending on the clock speed chosen. If you want to store six different messages or “tracks”, they can only be about seven seconds long each. For details on how to connect a button for each track, please refer to the diagram on page 70 of the December 2007 issue. Higher current rating for Charging Controller I am very interested in building the “Charging Controller for 12V LeadAcid Batteries”, as described in the August 2008 issue. The circuit looks ideal but the text does not give a current rating. If the limit is about 5A, can Q1 be upgraded or can another IRF9540 be wired in parallel for 10A or more? I have a 15A charger and I wish to add an appropriate controller to protect the battery being charged. At the mosiliconchip.com.au ment I am using a timer which limits the charge to two hours or less. (D. C., via email). • The IRF9540 MOSFET is rated to carry up to 19A continuously at 25°C, so it should be able to cope with your application. However you would need to put it on a fairly large and efficient heatsink, to help it cope with the dissipation (at 15A it will dissipate a little over 3W). Use an extruded aluminium heatsink, with a thermal resistance of 2.5°C/W or less. Musical Instrument Tuning Aid Thank you for the article in the July 2008 on the Musical Instrument Tuning Aid. I plan to build one and use it for tuning the wooden bars (notes) on a home made Marimba. I have used a commercially available tuner (Korg) for this purpose and found it to be very good. However, as a way of getting back into electronics after a “layoff” of many years, I thought I’d have a go at one of your projects. For the input I would need to use a suitable small “professional” microphone which won’t be exorbitantly expensive. Could you suggest a couple of suitable brands and models available through say Jaycar or Altronics? (J. S., via email). • Either the Jaycar AM-4090 dynamic microphone ($14.95) or the Altronics C-0383 ($45.00) microphone would be quite suitable for use with the Musical Instrument Tuning Aid. 15V DC power supply queries I have a 30V centre-tapped 500mA transformer that I would like to use with the ±15V DC Power Supply (SILICON CHIP, August 1988) for a future project. I know that the recommended transformer is a 150mA unit which is what I have used previously with other kits. Could the 500mA transformer be used instead of the 150mA unit and if so, would any changes be necessary to the on-board components? Would the extra current cause any increase in heat build-up in the 15V voltage regulators, as the instruction detail talks about the possible need for heatsinks on the regulators for higher voltages? (D. W., via email). • A 500mA transformer can be used siliconchip.com.au Blowing Up The CDI Inverter I built the inverter from the Multispark Capacitor Discharge Ignition system to provide a 375V supply to power a conventional CDI system. Needless to say, I blew it up! In a normal CDI, the SCR switches on and then stays on until the main capacitor is fully discharged. When using the Multi-Spark inverter, the voltage supply holds the SCR on indefinitely and burns out the inverters. How can I sense when the SCR is on in order to temporarily switch off the inverters until the capacitor is discharged and the SCR switches off and then use that to switch off the inverters the same way that the voltage is regulated via the 375V zener diodes? (J. B., Jarrow, UK). • The inverter section of the MultiSpark CDI was not designed to be if it has the same 30V centre tapping. Using the higher current rated transformer does not necessarily mean you need heatsinking. It is the current through the regulators (and the voltage between the regulator input and output) that causes the dissipation to rise. If you intend drawing more than 75mA from the ±15V rails, then heatsinking would be needed for the regulators. Flexitimer timing problem I have built the Flexitimer Mk.4 and found that when using the x10 feature, it only seems to work from 0-6. However, once you select 7-9 in the ON period, this will work fine but your OFF period goes way out. I have only tested it on the seconds selection but I am assuming it will be the same in minutes and hours. What do you think is likely to be the problem? (S. B., via email). • It’s not easy to suggest the cause of your Flexitimer’s strange misbehaviour. There should be no way that programming the ON period should change the OFF period, because they are quite independent of each other as far as the PIC’s internal program is concerned. It’s possible that there is a fault used in this way. As you have found, it does not switch off as it is continuously either charging or discharging the capacitor. The design allowed for very high spark-repetition rates of up to 1kHz. To stop this inverter would require extra circuitry and would depend on your CDI unit and how it triggers the SCR. Maybe the way to stop the inverter is to monitor the SCR current in your CDI and switch off the inverter while ever there is current flow. You would need a low-value sense resistor in the cathode to ground connection for the SCR. This would need to be amplified using an op amp (eg, an LM358). The op amp can then drive a transistor similarly to the voltage regulation transistor (Q3) to switch off the inverter. in your timer’s PC board or perhaps you may have accidentally fitted one of the diodes D1-D5 with the wrong polarity. Failing this, your PIC may not have been correctly programmed, in which case you should be able to send it back to Jaycar for them to program it again. How does a quartz watch work? I have been reading SILICON CHIP for seven years and find it very interesting and I have built some projects with good results. Quartz watches have been with us nearly 40 years now and a lot of people still don’t know how they work with that accuracy. So can you please publish an article on this subject? I am sure it will be very useful to many people. (T. P., Quakers Hill, NSW). • We described how crystal clocks work in the March 2008 issue, in an article entitled 1 PPS Driver for Quartz Clocks. Quartz watches work in exactly the same way. Mixer for multiple radios A lot of amateurs and others are installing multiple radios in cars these days. One bugbear is having a speaker for each radio. December 2008  89 Ignition System For A Stutz Bearcat I have a veteran motor car that has a magneto. The magneto is a bit unusual as the car has two spark plugs per cylinder, with one set of spark plugs over the inlet valves and the other set over the exhaust valves on the other side of the head (it is a “T” head configuration). The magneto is constructed so that the full secondary voltage (in theory, at least) can be directed to the “inlet” plugs for starting, after which the motor runs on both sets of plugs. The car is a 1916 Stutz Bearcat, with a 4-cylinder 6.3-litre engine which is difficult to crank so the magneto has a difficult time! The magneto is the major suspect for increasingly difficult starting and a misfire while idling. The magneto will be tested by a qualified person but the prognosis is not good. If the coils or condenser are suspect, then they must be repaired and rewound, respectively. The problem is that In my own case, I will be installing a UHF CB and UHF/VHF and HF sets in my new tourer. Many people doing outback touring (grey nomads) would have a CB and HF set. A kit that would combine multiple radio speaker outputs into one speaker would be ideal. You could use a mixer but there aren’t many around with, say, four inputs and then you have to have an amplifier and speaker; not very convenient. A simple unit that mixes and has a small amplifier would be popular. I do know of one commercial unit available magneto rewinders are a dying trade and there are very few people in this country that are qualified to do the work. Those who are have so much work that there is something like a 6-month wait to have the armature rewound. I have successfully constructed the Universal High-Energy Ignition System Mk.2 kit. The preamble to the assembly instructions for the ignition kit mentioned the use of magneto interrupter/points as a sort of reluctor. I am interested to know if there has been a simpler kit design that could be adapted to use the magneto points as the interrupter and the magneto distributor in the normal way, with the high-tension provided by perhaps two coils and two circuits driven by the one interrupter? The use of an electronic (as against the electric) spark generator would obviate the need to switch to the from overseas but it costs around $400 dollars. (L. W., via email). • Presumably when these multiple radios are in use, only one is actively receiving signals of interest at any one time. Therefore it would be a simple matter to have one speaker switched to the relevant radio using a relay and a priority switching circuit. In effect, it would be similar to a VOX circuit. If you just want a 12V mixer, have a look at our 4-input mixer in the June 2007 issue. It could be combined with a small 12V power inlet-only plugs for starting. It is important that the magneto remains on the engine, as the engine should still look to be original. Also, if I can arrange a rebuild, I will eventually go back to the magneto-only operation. (H. G., via email). • Using the magneto as a trigger and the points as a trigger are two separate things. You can use the magneto signal for triggering by building the reluctor version of the Universal High-Energy Ignition. Alternatively, you can use the points as the trigger by building the points version. The trigger can be used to drive two high-energy ignition systems that can then drive separate coils and the spark plugs. Alternatively, if the ignition coils do not draw any more than about 3A when saturated, it may be possible to connect two ignition coils in parallel and use the one Universal High-Energy Ignition to drive both. amplifier such as the Champ from the February 1994 issue. LED light with photocell I have constructed an anchor light for my boat using the strip of 27 LEDs from a 12V trouble-light that plugs into a cigarette lighter socket. Now I want to add a photocell to switch it on at dusk and off at dawn. When I wire in the cadmium sulphide photocell, it gives the opposite result and the light WARNING! SILICON CHIP magazine regularly describes projects which employ a mains power supply or produce high voltage. All such projects should be considered dangerous or even lethal if not used safely. Readers are warned that high voltage wiring should be carried out according to the instructions in the articles. When working on these projects use extreme care to ensure that you do not accidentally come into contact with mains AC voltages or high voltage DC. If you are not confident about working with projects employing mains voltages or other high voltages, you are advised not to attempt work on them. Silicon Chip Publications Pty Ltd disclaims any liability for damages should anyone be killed or injured while working on a project or circuit described in any issue of SILICON CHIP magazine. Devices or circuits described in SILICON CHIP may be covered by patents. SILICON CHIP disclaims any liability for the infringement of such patents by the manufacturing or selling of any such equipment. SILICON CHIP also disclaims any liability for projects which are used in such a way as to infringe relevant government regulations and by-laws. Advertisers are warned that they are responsible for the content of all advertisements and that they must conform to the Trade Practices Act 1974 or as subsequently amended and to any governmental regulations which are applicable. 90  Silicon Chip siliconchip.com.au only works during the day. What do I have to do to make this work correctly? Except for the basics, I am electronically challenged, so please keep it simple. (A. B., via email). • You have evidently placed the LDR (photocell) in series with the supply to the LEDs. The LDR has low resistance at high light levels and so the LEDs light. You need to reverse this operation for night-time lighting. We published a Sunset Switch (June 2003) that could be operated from 12V instead of the 240VAC mains. This drives a relay that can power the LED lights during darkness. Line input for voice recorder module I have built the Enhanced Voice Recorder Module (Dec­ember 2007) and plan to use it as a custom doorbell. Is it possible to modify the circuit to take a line-in input (eg, from computer or MP3 player) in lieu of the condenser microphone? (S. F., via email). • It’s quite easy to modify the Voice Recorder module to accept an audio line-level input instead of the electret mic. All that is needed is to remove the 100nF capacitor linking pins 20 and 21 of the HK828 chip, and then couple in the line-level audio to pin 20, via another (or the same) 100nF coupling capacitor. It would also be a good idea to use a 50kΩ trimpot ahead of the coupling capacitor, to allow you to adjust the level of the incoming audio and prevent overloading the HK828. Just connect the trimpot as a volume control, with its wiper connected to pin 20 of the IC via the 100nF capacitor. Waterproof connectors needed for charger I’m looking for some type of connector, to be mounted on the outside of an enclosure, that is somewhat waterproof or has a dustcover of some sort. I was thinking of some sort of banana plug but I it might corrode. Would you know of any 2-way plug that can either be panel mounted or has a dust cover or similar? The plug has the purpose of allowing the user to connect a charger into the unit which has an internal battery. Thanks for any suggestions. (B. W., via email). • There are a few that can be used: siliconchip.com.au How To Zap 8V Batteries Before I start assembly of my Jaycar Lead Acid Battery Zapper/Tester kit (SILICON CHIP, May 2006), I am curious if this device (with minor modifications) can also be used with 8V lead acid batteries? To explain, I have a 1939 ChrisCraft speedboat that I converted to 8V to make it easier to start. I also have an electric boat that is 24V but I can zap it as two independent 12V batteries. So there appear to be two options: modify the 6V setting on the Zapper or modify the 24V circuit and dedicate it to 8V. Since I also have 6V batteries for my 1925 Studebaker and my 1931 Model A Ford, modifying the 24V circuit would be preferable. (S. U., Saratoga Springs, NY, USA). • The zapper section of the Battery Zapper/Tester should be able to work satisfactorily with an 8V battery, without any changes. However, (1) The Jaycar PS-0789 and PS-0787 IP67-rated connector; (2) A BNC or an F connector could be used (panel-mount BNC or F socket and line plug); (3) Banana sockets such as the insulated PS-0420 from Jaycar. This has the disadvantage that the polarity could be incorrect when plugging in the plugs, (ie, not polarised); (4) A 2-pin DIN panel socket and line plug (Jaycar PS-0430 and PP-0300). The back of the socket can be sealed using neutral-cure silicone sealant after the wires have been soldered on; (5) IP67-rated multi-pole connectors, eg, Jaycar PP-1006 and PS-1007; (6) Farnell (www.farnellinone.com.au) you would need to make a few minor changes to the condition tester section, in order to check 8V batteries. As you suggest, this could be done by taking over the 24V positions of S2a and S2b. We suggest that you try connecting a 22kΩ resistor in series with the 24V position of S2a, and connect the 24V position of S2b to the junction between the two upper 220Ω resistors in the voltage divider associated with S2b, rather than the existing connection between the two lower 220Ω resistors. This should effectively convert the 24V range into an 8V range, although you may need to change the value of the uppermost 220Ω resistor to 110Ω and the one below it to 330Ω. By the way, as a general rule, if your batteries are behaving normally and hold a good charge, there should be no need to zap them. would have more options for IP67rated connectors. Power pack for Tempmaster Could you please advise the specifications (output, etc) for a suitable powerpack for the Tempmaster (SILICON CHIP, June 2005)? The article does not make any mention of this. (L. P., via email). • The current drain of the low voltage circuitry in the Tempmaster is very low indeed at less than 15mA. This means that you can use a low-power plugpack, with a rating of 100mA or SC less. Notes & Errata AirNav RadarBox, November 2008: the contact email address given on page 16 should be jparncut<at>bigpond.net.au Subwoofer Controller, August 2007: a short copper track is missing on the final version of the PC board file. The missing track should be running directly under the centre of diode D5, connecting pin 1 of IC4 to the wide earth track running transversely just behind D5. To fix this problem in existing boards, solder a short length of tinned copper wire in place of the missing track. A corrected version of the PC board file will be sent to board manufacturers. December 2008  91 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* 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. 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. 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. 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 PRACTICAL RF HANDBOOK by Carl Vogel. Published 2009. $40.00* by Ian Hickman. 4th edition 2007 $61.00* A guide to RF design for engineers, technicians, students and enthusiasts. Covers key topics in RF: analog design principles, transmission lines, couplers, transformers, amplifiers, oscillators, modulation, transmitters and receivers, propagation and antennas. 279 pages in paperback. Alternative fuel expert Carl Vogel gives you a hands-on guide with the latest technical information and easy-to-follow instructions for building a two-wheeled electric vehicle – from a streamlined scooter to a full-sized motorcycle. 384 pages in soft cover. *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. 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, PROGRAMMING 32-bit MICROCONTROLLERS IN C By Luci di Jasio (2008) $79.00* 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. PRACTICAL GUIDE TO SATELLITE TV 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. 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. 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. See Review March 2010 See Review Feb 2004 SWITCHING POWER SUPPLIES A-Z 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. 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. 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 PRACTICAL RF HANDBOOK by Ian Hickman. 4th edition 2007 $61.00* by Douglas Self 2nd Edition 2006 $69.00* by Carl Vogel. Published 2009. $40.00* A guide to RF design for engineers, technicians, students and enthusiasts. Covers key topics in RF: analog design principles, transmission lines, couplers, transformers, amplifiers, oscillators, modulation, transmitters and receivers, propagation and antennas. 279 pages in paperback. Alternative fuel expert Carl Vogel gives you a hands-on guide with the latest technical information and easy-to-follow instructions for building a two-wheeled electric vehicle – from a streamlined scooter to a full-sized motorcycle. 384 pages in soft cover. *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 PAYPAL (24/7) INTERNET (24/7) MAIL (24/7) PHONE – (9-5, Mon-Fri) eMAIL (24/7) FAX (24/7) To siliconchip.com.au December Use your PayPal account www.siliconchip. Call (02) 2008  93 9939 3295 with silicon<at>siliconchip.com.au Your order and card details to Your order to PO Box 139 Place com.au/Shop/Books silicon<at>siliconchip.com.au Collaroy NSW 2097 with order & credit card details with order & credit card details (02) 9939 2648 with all details Your You can also order and pay for books by cheque/money order (Mail Only). Make cheques payable to Silicon Chip Publications. Order: ALL TITLES SUBJECT TO AVAILABILITY. PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. ALL PRICES INCLUDE GST MARKET CENTRE Cash in your surplus gear. Advertise it here in SILICON CHIP FOR SALE RCS RADIO/DESIGN is at 41 Arlewis St, Chester Hill 2162, NSW Australia 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 Battery Packs & Chargers Siomar Battery Engineering www.batterybook.com Phone (08) 9302 5444 CUSTOMERS: Truscotts Electronic World – large range of semiconductors and passive components for industry, hobbyist and amateur projects including Drew Diamond. 27 The Mall, South Croydon, Melbourne. (03) 9723 3860. electronicworld<at>optusnet.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 TECH REPAIRS SERVICE MANUALS www.techrepairs.org Thousands of downloadable service manuals for all brands, makes and models including PDP, LCD, VCR, DVD, CTV, Vintage Radio, Laptops, Monitors, Sewing Machines, Washing Machines, Dryers, Fridges and many more. An absolute must have website for any Tech! LEDs! NICHIA SUPERBRIGHT LEDs, Cree XR-E and 5mm LEDs, Avago (HP) LEDs, many other standard and superbright brand name LEDs. Plus, see our new range of nixie clocks! www. ledsales.com.au KIT ASSEMBLY From the publi shers of Intelligent Looking for real performance? turbo timer I SBN 095852 294 - 4 TURBO BOOS T & nitrous fuel con trollers 9 780958 522946 $19.80 (inc GST) NZ $22.00 (inc GST) How engine management wor ks • Learn about engine management systems • Projects to control nitrous, fuel injection and turbo boost systems • Switch devices according to signal frequency, temp­erature & voltage • Build test instruments to check fuel injector duty cycle, fuel mixtures and brake & temperature Mail order prices: Aust. $A22.50 (incl. GST & P&P); Overseas $A26.00 via airmail. See www.siliconchip.com.au for ordering details. DOWNLOAD OUR CATALOG at KEITH RIPPON KIT ASSEMBLY & REPAIR: * Australia & New Zealand; * Small production runs. Phone Keith 0409 662 794. keith.rippon<at>gmail.com www.iinet.net.au/~worcom WORLDWIDE ELECTRONIC COMPONENTS PO Box 631, Hillarys, WA 6923 Ph: (08) 9307 7305 Fax: (08) 9307 7309 Email: worcom<at>iinet.net.au PRINTED • • • • • • • Prompt Response Reliable Service On-Time Delivery Tested Products Outstanding Quality Satisfaction Guaranteed 1/2/3/5/7 Day Deliveries Also Nameplates, Engraving Builders Plates Screenprints Membranes 96 Malcolm Rd, Braeside Vic 3195 Tel: 03 9588 2828 Fax: 03 9588 2818 Email: sales<at>pcbeze.com 94  Silicon Chip siliconchip.com.au AT LAST! VIDEO - AUDIO - PC distribution amps - splitters digital standards converters - tbc's switchers - cables - adaptors genlockers - scan converters bulk vga cable - wallplates Quality batteries for power tools at prices you CAN AFFORD! CALL: PREMIER BATTERIESPTY LTD MD12 Media Distribution Amplifier QUEST ® (02) 9755 1845 VGA Splitter VGS2 email: malcolmw<at>premierbatteries.com.au web: www.premierbatteries.com.au HQ VGA Cables IMAGECRAFT C COMPILERS ANSI C compilers, Windows IDE AVR, TMS430, ARM7/ARM9 68HC08, 68HC11, 68HC12 GRANTRONICS PTY LTD ® 20 years experience! Quest Electronics® Pty Limited abn 83 003 501 282 t/a Questronix Products, Specials & Pricelist at www.questronix.com.au fax (02) 4341 2795 phone (02) 4343 1970 email: questav<at>questronix.com.au HI-FISPEAKER REPAIRS YOUR EXPERT SPEAKER REPAIR SPECIALISTS Tough times Specialising in UK, US and Danish brands. Speakerbits are your vintage, rare and collectable speaker repair experts. Foam surrounds, voice coils, complete recone kits and more. Original OEM parts for Scan-Speak, Dynaudio, Tannoy, JBL, ElectroVoice and others! demand innovative solutions! SPK360 C O N T R O L S 2 x 100MSa/s 10bit inputs + trigger 100MHz bandwidth 8 x digital inputs 4M samples/input Sig-gen + spectrum analyser Windows 98/Me/NT/2k/XP SPK360 3/5/06 1:10 PM Page 1 www.grantronics.com.au AWP1 A-V Wallplate Come to the specialists... High quality Realistic prices Free software updates Large range of adaptors Windows 95/98/Me/NT/2k/XP CLEVERSCOPE USB OSCILLOSCOPES DVS5c & DVS5s High Performance Video / S-Video and Audio Splitters Quest AV® ELNEC IC PROGRAMMERS tel: 03 9647 7000 www.speakerbits.com Surplus Electronic Components ABN: 38 445 311 223 www.excesselectronics.com.au Made in Australia, used by OEMs world-wide splat-sc.com Excess Electronic Components SMD Led (Pk-100) PO Box 2417 AB687 Rowville Vic 3178 Tel: 041 567 7761 $ 3.00 Fax: 03 9755 8280 On-line Shopping FREE MONTHLY MAILER Range Of Excess Please Enquire Electronic Parts sales<at> excesselectronics.com.au 30mcd Dark Blue FREE FREIGHT FOR ORDER OVER $100 Silicon Chip Binders H Each binder holds up to 12 issues H SILICON CHIP logo printed on spine & cover Price: $A13.95 plus $A7.00 p&p per order. Available in Australia only. Buy five and get them postage free. Just fill in & mail the handy order form in this issue; or fax (02) 9979 6503; or ring (02) 9979 5644 & quote your credit card number. siliconchip.com.au 42 REAL VALUE AT $13.95 PLUS P & P Silicon Chip Circuit 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 $100 for a good circuit idea or you could win some test gear, including an LCR Meter, a Semiconductor Component Analyser, an ESR Analyser or a Thyristor & Triac Analyser. Silicon Chip Publications, PO Box 139, Collaroy, NSW 2097. Silicon Chip December 2008  95 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 50 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. Send to: Retail Operations Manager - Jaycar Electronics Pty Ltd PO Box 107, Rydalmere, NSW 2116 Email: jobs<at>jaycar.com.au Jaycar Electronics is an equal opportunity employer and actively promotes staff from within the organisation. CLASSIFIED ADVERTISING RATES Advertising rates for these pages: Classified ads: $29.50 (incl. GST) for up to 20 words plus 85 cents for each additional word. Display ads: $54.50 (incl. GST) per column centimetre (max. 10cm). Closing date: 5 weeks prior to month of sale. To book your classified ad, email the text to silicon<at>siliconchip.com.au and include your name, address & credit card details, or fax (02) 9939 2648, or post to Silicon Chip Classifieds, PO Box 139, Collaroy, NSW, Australia 2097. _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ Enclosed is my cheque/money order for $­__________ or please debit my o Visa Card   o Master Card Card No. Signature­­­­___­­­­­­­­__________________________ Card expiry date______/______ Name _________________________________________________________ Street _________________________________________________________ Suburb/town ______________________________ Postcode______________ Phone:______________ Fax:______________ Email:___________________ 96  Silicon Chip Advertising Index AJ Distributors................................. 58 Altronics............................ loose insert Amateur Scientist CDs.................. IBC Av-Comm........................................ 59 Computronics.................................. 95 Dick Smith Electronics............... 26-27 Ecowatch........................................ 94 Emona Instruments......................... 43 Excess Electronics.......................... 95 Front Panel Express.......................... 9 Gless Audio..................................... 58 Grantronics..................................... 95 Harbuch Electronics........................ 39 Hare & Forbes..............................OBC Hills Industries................................ 59 Instant PCBs................................... 95 Jaycar..............................IFC,45-52,96 JED Microprocessors........................ 5 Keith Rippon................................... 94 LED Sales....................................... 94 Microgram Computers.................... 58 MicroZed Computers........................ 7 Ocean Controls................................. 8 Onboard Solutions.......................... 58 Ozitronics........................................ 39 PCBEZE.......................................... 94 Premier Batteries............................ 95 Quest Electronics............................ 95 RCS Radio...................................... 94 RF Modules................................ 59,96 RMS Parts....................................... 38 Sesame Electronics........................ 94 Silicon Chip Binders........................ 95 Silicon Chip Bookshop............... 92-93 SC Perf. Electronics For Cars.... 57,94 Silicon Chip Order Form................. 77 Siomar Battery Industries............... 94 Soundlabs Group............................ 11 Speakerbits..................................... 95 Splat Controls................................. 95 Tech Repairs................................... 94 Tekmark Australia........................ 9,59 Tenrod............................................. 71 Tribotix .............................................. 3 Truscotts Electronic World............... 94 Wagner Electronics......................... 41 Worldwide Elect. Components........ 94 PC Boards Printed circuit boards for SILICON CHIP designs can be obtained from RCS Radio Pty Ltd. Phone (02) 9738 0330. Fax (02) 9738 0334. siliconchip.com.au STIC FANTAIDEA GIFT UDENTS FOR SFT ALL O S! AGE THEAMATEUR SCIENTIST An incredible CD with over 1000 classic projects from the pages of Scientific American, covering every field of science... THE LATEST VERSION 4 – WITH EVEN MORE FEATURES! Arguably THE most IMPORTANT collection of scientific projects ever put together! This is version 4, Super Science Fair Edition from the pages of Scientific American. As well as specific project material, the CDs contain hints and tips by experienced amateur scientists, details on building science apparatus, a large database of chemicals and so much more. ONLY 62 $ 00 PLUS $10 Pack and Post within Australia NZ P&P: $AU12.00, Elsewhere: $AU18.00 “A must for every science student, science teacher, science lab . . . or simply for those with an enquiring mind . . .” Just a tiny selection of the incredible range of projects: ! Build a seismograph to study earthquakes ! Make soap bubbles that last for months ! Monitor the health of local streams ! Preserve biological specimens ! Build a carbon dioxide laser ! Grow bacteria cultures safely at home ! Build a ripple tank to study wave phenomena ! Discover how plants grow in low gravity ! Do strange experiments with sound ! Use a hot wire to study the crystal structure of steel ! Extract and purify DNA in your kitchen !Create a laser hologram ! Study variable stars like a pro ! Investigate vortexes in water ! Cultivate slime moulds ! Study the flight efficiency of soaring birds ! How to make an Electret ! Construct fluid lenses ! Raise butterflies as experimental animals ! Study the physics of spinning tops ! Build an apparatus for studying chaotic systems ! Detect metals in air, liquids, or solids ! Photograph an ant's brain and nervous system ! Use magnets to make fluids into solids ! Measure the metabolism of an insect . . . ! and many, many more (a thousand more, in fact!) See the V2 review in SILICON CHIP, October 2004. . . or read on line at siliconchip.com.au This is the ALL-NEW Version 4 . . . it’s even BETTER! HERE’S HOW TO ORDER YOUR COPY: BY PHONE:* (02) 9939 3295 9-5 Mon-Fri BY FAX:# <at> (02) 9939 2648 24 Hours 7 Days BY EMAIL:# silicon<at>siliconchip.com.au 24 Hours 7 Days BY MAIL:# BY PAYPAL:# PO Box 139, Collaroy NSW 2097 silicon<at>siliconchip.com.au 24 Hours 7 Days * Please have your credit card handy! # Don’t forget to include your name, address, phone no and credit card details. BY INTERNET:^ siliconchip.com.au 24 Hours 7 Days ^ You will be prompted for required information There’s also a handy order form inside this issue. Exclusive in SILICON Australia to: CHIP siliconchip.com.au siliconchip.com.au December 2008  97