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SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au Contents Vol.20, No.6; June 2007 SILICON CHIP www.siliconchip.com.au Features 10 VAF’s New Soundwall Is it a wall or is it a loudspeaker? – by Ross Tester 12 Turntables – Give ’em A Spin; Pt.2 We look at the software you’ll need to clean up those old vinyl recordings and save them to CD – by Barrie Smith 78 The Latest PICAXE Developments PICAXE designers Revolution Education Ltd have been hard at work. Here’s a look at the latest developments in the PICAXE world – by Clive Seager Building Mirror Image Class-A Amplifier Modules – Page 20. 86 A Flying Visit To CeBIT Australia 2007 There were lots of interesting products at this year’s show – by Ross Tester Pro jects To Build 20 20W Class-A Amplifier Module; Pt.2 Building mirror-image left and right channel modules, plus power supply circuit and assembly details – by Leo Simpson 42 A Knock Detector For The Programmable Ignition Use it to help program ignition timing and/or to automatically retard the ignition timing in response to engine knock levels – by John Clarke 58 Versatile 4-Input Mixer With Tone Controls Knock Detector For The Programmable Ignition – Page 42. New design features tone controls, a headphone amplifier and four low-noise inputs that can be configured to suit your signal sources – by Jim Rowe 75 Fun With The New PICAXE 14-M Here’s a close-up look at the new kid on the block – by Stan Swan 82 Frequency-Activated Switch For Cars A cheap, adjustable design that lets you switch devices on and off according to speed – by John Clarke & Julian Edgar 89 Simple Panel Meters Revisted Woops!! Several readers have had problems but not of their own making – by Ross Tester Special Columns 38 Circuit Notebook (1) Simple Battery Isolator; (2) Using The PICAXE In SPI Mode; (3) LED Stroboscope Uses A Frequency Counter To Measure RPM; (4) Egg Timer 4-Channel Mixer – Page 58. 70 Serviceman’s Log The need to eat and pay bills – by the TV Serviceman 90 Vintage Radio DC-To-AC Inverters From The Valve Era – by Rodney Champness Departments   4   6 57 81 Publisher’s Letter Mailbag Product Showcase Order Form siliconchip.com.au 96 Ask Silicon Chip 99 Notes & Errata 102 Market Centre Frequency Switch For Cars – Page 82. June 2007  1 Great Savings On… SOLDERING WTCPTD Soldering Station STORAGE & ENCLOSURES Multipurpose – ‘Adapatable’ (PCB Guides) Enclosure • Soldering station, 42W • Power, output:60W • Voltage, supply AC:24V $160.00 ORDER CODE 317-6940-04 Tip Cleaner • Suitable for use with lead-free and conventional solders • 599B is coated with flux and no water is required to clean tips • When using lead-free solder, tip oxidize easily because of higher temperatures being used $14.00 ORDER CODE • Attractive matt finish • Vertical PCB guides and bosses molded in lid and base of box Colour Black Black Black White White H 178 178 178 178 65 W 122 122 122 122 240 D 36 55 74 36 190 ORDER CODE $2.50 723-3188-04 Multi Compartment Boxes 8 No of 9 Compartment 12 24 • Length / Height, external: 85mm • Width, external: 56mm • Depth, external: 39mm • Material: Polystyrene • Colour: Black • IP rating: IP54 W 56 50 62 $35.00 • See through lid • Lock tight latch keeps lid tightly closed Box, Styrene 85x56x39 Black L 85 100 112 Height: 254mm Length: 330mm Weight: 1.6kg Width, external: 178mm ORDER CODE Ordercode Price 938-853-04 $8.00 938-865-04 $8.50 938-877-04 $9.00 938-889-04 $9.00 536-8716-04 $18.00 466-3329-04 988-7091-04 • • • • • Lid screws can be inserted from either side and can be hidden by matching covers Lead Free Solder • 2 meter length of lead-free solder wire • Mildly activated no-clean flux formulation • Increased flux content (3% by weight Hard bottom Tool Case H 35 40 40 55 W 230 180 180 340 D 170 130 130 230 Order Code Price 386-1855-04 $4.00 386-1880-04 $4.00 386-1909-04 $4.00 386-1820-04 $18.00 Seal Tight Organiser • Up to 25 compartments • Moveable dividers allow customisation • See through lid • Seal tight compartment latch keeps heavy components in place D Order code Price 39 353-6488-04 $4.50 25 353-6490-04 $5.40 31 353-6506-04 $6.00 $15.00 ORDER CODE 335-5469-04 TOOLS Inspection Mirror Multi Test Screw Driver • INSP’ MIRROR 55MM DIA X 370MM • Diameter, external:55mm • Length:370mm $15.00 ORDER CODE 109-166-04 Telescopic Magnetic Pickup Tool • • • • • • • Continuity measuring ranges:0 - 50000000 ohms Microwave Leakage Detection:>5mW/cm² Polarity Test Range:1.2- 36 V dc Safety Barrier:16M ohm resistor Time, battery life:5h Voltage, test contact/contact:250V Voltage, test direct contact:70 - 250V ac. Up to 250V dc $16.00 ORDER CODE 500-823-04 Mini Pliers Set –6PCS • Magnetic tip on an extendable chrome-plated blade • Extendable blade length = 170mm to 540mm ORDER CODE • Jaw type:Round nose, Long nose, Flat Nose, Bent nose, Diagonal cutter • Handle type:PVC Dipped $8.00 312-5671-04 $17.00 Screwdriver Set ORDER CODE • SCREWDRIVER SET, 6 PC • Kit contents:Slot 1.4 x 20mm, 1.8 x 20mm, 2.4 x 20mm,Phillips No.00 20mm, No.0 20mm, No.1 20mm Digital Callipers $15.00 ORDER CODE 2  Silicon Chip 115-6000-04 312-5555-04 • Graduation:0.01mm • Range, measuring max:150mm Resolution:0.01mm $29.00 ORDER CODE 470-4400-04 ORDER NOW at www.farnell.com.au or Call 1300siliconchip.com.au 361 005 A Premier Farnell Company Great Savings On… MEMORY POWER PROTECTION Credit Card Flash Drive • • • • • Single Power & Telecom Protector USB Credit card Flash Drive Connector type: USB Length / Height, external: 84mm 15 Years RTB warranty Gift boxed FREE Company Logo Customizing Service Call us for details 134-3948-04 $39.00 134-3949-04 $59.00 134-3950-04 $85.00 134-3951-04 $150.00 USB Flash Drive $10.00 340-7329-04 ORDER CODE • Current, surge: 18000A • Ideal for glove box, cupboard and suitcase • Hardwearing canvas red case • Dimensions (WxHxD): 200 x 130 x 65 mm $39.00 ORDER CODE 122-2348-04 $22.50 Power Centre • Connector type A: 3 Pin Aus Mains Plug • Connector type B: 2 x 3 Way Aus Mains Sockets • Length, lead: 1.8m • Cable type: 1.8m Heavy Duty • Voltage rating, AC: 240V • Approval Bodies: AS/NZS 3012 • IP rating: IP33 • Power, load: 2400W ORDER CODE $25.00 ORDER CODE 350-9369-04 2 Way Car Alarm • Covering a 2-Way range of over 3000-ft • The transmitter unit will send out warning beeps every 20 seconds when your car has been compromised and visually show on the LCD panel what has been violated • Remotely set off panic mode to scare off potential intruders and shut off engine every 3hrs to keep engine warm in cold weather • Must be installed by a .00 professional auto electrician 122-2753-04 $170 ORDER CODE LCD Virtual Glasses • Advance ergonomic design • 7 styles, 2 character sizes, fixed length, multiple copies • Uses 6xAAA batteries (Not supplied) $100.00 $70.00 902-7432-04 BATTERIES Electronic stapler 12mm sheet capacity Auto front loading Uses 4AA batteries (not included) Alkaline Batteries Bulk Packs ORDER CODE V 1.5 1.5 1.5 1.5 9 Digital Multimeter • • • • Continuity buzzer Data hold Full icon display Included standard test leads, plus separate short leads for accurate capacitance check • Meets 1000V CATII standards Order code 381-5225-04 381-5213-04 381-5237-04 381-5249-04 381-5250-04 Battery, Ni Oxy Hydroxide Type QTY Order code Price AA 2 117-8541-04 $5.50 AA 4 1178540-04 $9.50 AAA 2 117-8542-04 $5.50 Price $16.00 $19.00 $19.00 $26.00 $29.00 $35.00 ORDER CODE ORDER CODE • USB interface for set-up and data download • 16,000 readings, with –25 to +80°C measurement range • 2 User-programmable alarm thresholds $89.00 ORDER CODE A Premier Farnell Company 491-3437-04 Voltage with Light Tester Type QTY Order code Price AA 2 117-8537-04 $11.90 AA 4 117-8538-04 $19.90 125-0228-04 ORDER NOW at www.farnell.com.au or Call 1300 361 005 siliconchip.com.au 743-0574-04 USB Datalogger Battery Nimh AA 2650 MAH Rechargeable $249.00 132-5443-04 TEST & MEASUREMENT • The most powerful Duracell alkaline battery ever made • Lasts up to 50% longer than standard Duracell in high drain devices • Long shelf life • Powercheck – a unique built-in power gauge that allows you to see how much battery power you have left Type QTY AAA Ultra 24 AA Ultra 24 C Ultra 12 D Ultra 12 9V Ultra 12 436-2123-04 LabelPoint 150 ORDER CODE GADGETS 410-8747-01 First Aid Kit, Handy 3 Call us for details • Speedy: Up to 22.5MB/sec. read rate and 17MB/sec write rate • Secure: Built-in write-protect switch prevents accidental data loss • Simple - as easy as plug-and-play 1GB 119-3365-04 $45.00 2GB 119-3364-04 $75.00 4GB 119-3362-04 $120.00 • Clear 36inch (800x225) resolution picture accompanied by Hi-Fi stereo sound • Input signal: NTSC/PAL colour video signal • Comes with glasses, eye patch, AC adaptor and RCA leads 100x100mm Natural ties (up to 8kg strength) 100x100mm Coloured ties (up to 8kg strength) 50x200mm Natural ties (up to 8kg strength) 50x200mm Coloured ties (up to 18kg strength) 50x280mm Coloured ties (up to 22kg strength) PS-100 Company Logo Customizing Service High Speed SD Cards 150x • • • • Includes the following lengths: $30.00 ORDER CODE FREE • 15 Years RTB warranty 1GB 912-6937-04 $39.00 2GB 965-2507-04 $59.00 4GB 121-0888-04 $85.00 8GB 119-3355-04 $150.00 Staple Wizard Cable Tie Assortment 350 Pieces • Connector type A: 3 Pin Plug • Connector type B: RJ45 or RJ12 • Width, external: 53mm Pack Quantity: 1, Width, external: 53mm, Depth, external: 4mm, Operating system software: Windows 98/98SE/ME/2000/XP 1GB 2GB 4GB 8GB ACCESSORIES • • • • • • Battery size code: AAA Depth, external: 233mm Length / Height, external: 245mm Temp, op. max: 50°C Temp, op. min: 0°C Voltage measuring ranges, AC: 40V to 300V a.c $45.00 ORDER CODE 800-2207-04 June 2007  3 SILICON CHIP www.siliconchip.com.au Publisher & Editor-in-Chief Leo Simpson, B.Bus., FAICD Production Manager Greg Swain, B.Sc.(Hons.) Technical Staff John Clarke, B.E.(Elec.) Ross Tester Jim Rowe, B.A., B.Sc, VK2ZLO 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 Kevin Poulter 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 subscription page 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. 4  Silicon Chip Publisher’s Letter Business energy use can be greatly reduced There has been much derision of the emissions reduction target recently set by the Leader of the Opposition, Kevin Rudd. The target of a 60% reduction by the year 2050 may seem steep, particularly as the Australian economy and population will undoubtedly grow considerably over the next four decades. But is a target of a 60% cut really so silly? The typical domestic consumer may well be able to reduce energy usage by that amount over a decade or so but will business be able to do the same? That is a huge topic and the first question that must be asked is: will the business still be able to grow and increase employment? If employment is to increase, it normally means that energy use must also increase. But say we decree that a business must cut its energy use per employee by 60%? Would that be feasible? The answer is: probably. However, a prerequisite for any energy cuts is that they must not reduce staff safety, comfort and productivity. I have been thinking about whether we at Silicon Chip Publications could reduce our own energy use markedly. The answer has to be that we can make major reductions, without even investing in new technology. Our building certainly has not been designed with energy conservation in mind. While the steel roof is insulated and does have a large passive extractor to vent excessive heat from the warehouse, it still needs a big airconditioner to keep the office area comfortable, particularly in summer. Hence, our main energy users are the airconditioner, office & warehouse lighting, hot water system and computers. Since moving in about 10 months ago, we have already made changes which have resulted in major energy reductions compared with the previous occupants, while not prejudicing comfort or safety in any way. For example, I had an electrician do a lot of work in fixing and updating exit lights, emergency lighting, re-tubing the lights in a separate factory warehouse and so on. While he was doing that work, I had him set back the hot water system thermostats to 60°C, which is now a Worksafe requirement. This reduces the risk of scalding, reduces power consumption and as bonus, the tanks will probably last quite a bit longer. I also had the warehouse light switching changed so that a bank of fluorescent lights did not have to be left on all day – they were normally kept on so that the kitchen and mailing areas were always lit. That amounts to a major saving in energy over a year. As well, automatic door closers were fitted to two doors so that hot or cold air from the warehouse did not blow into the airconditioned office. The warehouse roller shutter and office entrance doors (also now fitted with an automatic closer) are also kept closed all the time. Overall, such modest changes have probably cut energy use by at least 50% and we haven’t been really trying. Without drastic changes, we can probably make a further significant reduction in power consumption from the office lighting while improving overall illumination. And it should not be hard to reduce energy consumption of the computers in the future – laptops already use much less power than desktop machines. With significant cuts in energy use from lighting and computers, the summer airconditioning load will also be reduced. In winter time, there may not be much benefit but you can see that reducing energy use in the typical office is not rocket science. Have a think about your own work-place and see if it would not be equally easy to make reductions in energy use. You will probably be surprised at the possibilities. Leo Simpson siliconchip.com.au Work on an engine so big, it fills an entire room. APPRENTICESHIP SPECIFICATIONS Once you get onboard the ship you continuously build up your skills with all the on the job training. NATIONAL QUALIFICATIONS Jacki Irwin Navy Marine Technician GREAT PAY GUARANTEED JOB NO PRIOR EXPERIENCE For your free Trade Careers CD ROM simply call 13 19 01, or visit www.defencejobs.gov.au Whilst you’ll be busy doing your apprenticeship, there’s always plenty of time for play. Onboard the ship you’ll have access to a range of gym facilities. You may even find yourself exercising on the ship’s flight deck. Two General Electric LM2500 gas turbines on the Navy’s fleet of FFG Frigates drive a single controllable pitch propeller. NAVY TRADES Electronics Technician Marine Technician GPY&R MDFN0873/SC (Mechanical or Electrical) Aviation Technician - Aircraft Aviation Technician - Avionics siliconchip.com.au If you’re good with your hands, the Navy opens up an exciting world of apprenticeship training unlike anything you’ll find anywhere else. As a Marine Technician, you’ll be responsible for maintaining the ships’ propulsion systems, gas turbines, electrical power generators and auxiliary systems. For more information on other Electronic and Mechanical trade careers, and to order your free CD ROM, call 13 19 01 or visit www.defencejobs.gov.au You’ll be paid a great wage while you train. You’ll start on $25,400p.a. and after 2 years you can earn from $46,600p.a. Plus you’ll receive a $9,300p.a. seagoing allowance. You’ll enjoy all sorts of benefits like free medical and dental, plus subsidised meals and accommodation. June 2007  5 Call 13 19 01 or visit www.defencejobs.gov.au 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”. Cure for ECG software problem I write in response to two letters in the “Ask SILICON CHIP” pages of the March 2007 issue. The first concerns ATX power supply plugs. While I do not know of a potential source of the 20-pin Molex PSU plug, I must say that if the original plug has overheated due to poor contact, then the PSU plug and motherboard socket should be replaced as a pair, otherwise the problem could recur. Secondly, it appears that constructors continue to have software issues with your ECG project. I drew attention to this problem more than a year ago and provided an explanation and a solution. There was also a recent thread at the aus.electronics newsgroup initiated by another constructor with the same problem – see http://groups. google.com/group/aus.electronics/ msg/f82bad9e524f56c0?dmode=sour ce&hl=en “The software misbehaves until Casting a pall on fluorescent lighting I read your article in the April 2007 edition of SILICON CHIP with interest but one point that you didn’t raise is that of the quality of the light produced by “fluoro” lighting. Fluorescent lighting has long been known to be more efficient than incandescent and has been available for many years. In fact, lighting systems that operate via gas discharge principles are many and varied. Sodium vapour, mercury vapour and metal halides all operate on the principle of exciting electrons into higher energy orbits which then emit photons (light) when they collapse down to lower energy orbits; the reverse of Einstein’s photoelectric effect. The problem is that the light that they produce is usually narrow in 6  Silicon Chip such time as an ECGSAMPL.cfg file is created, after which it works flawlessly. If this file is subsequently deleted (or renamed), the software plays up again. In my case, the reason this file was not being created was because I was closing the application by clicking on the “X” in the top righthand corner of the program window instead of selecting File -> Exit. I suggest that you configure your settings, then select File->Exit to save your ECGSAMPL.cfg file. Then relaunch your program and all should be well”. Franc Zabkar, Barrack Heights, NSW. Another solution to speedo error After reading the letter from Jack Chomley regarding odometer readings (February 2007), I would like to share an idea for error correction of a car speedo on an otherwise unmodified car which has worked for me. I frequency and therefore quite unpleasant. It’s usually green, blue or orange-tinged and very unflattering. This effect is even more noticeable in photography, where photographs taken under gas discharge and fluorescent lighting have very strange and unacceptable colour casts. Incandescent lighting is quite low in colour temperature (around 3800 Kelvin) which has a pleasant “warm” quality which works very well with interior decorating and is flattering to the human skin. Further, 12V halogen lighting has the advantage of producing light that is higher in colour temperature (closer to daylight) because the filament burns at a higher temperature. However, the light is still within the pleasant “warm” range, with no unpleasant red-green shift. The other advantage of 12V halo­ built and installed the Speed Alert kit (SILICON CHIP, November & December 1999). Then, using a handheld GPS, I calibrated the Speed Alert kit to the GPS reading. When the Speed Alert kit is in speedometer mode, it displays the correct vehicle speed and the original speedo remains unmodified and legal. The LED displays can be mounted on a small satellite PC board to make the unit less obtrusive. All of the above assumes that the car is unmodified. If you’ve changed your differential or gearbox, you could still use the Speedo Corrector to calibrate the odometer against a GPS. Then use the Speed Alert kit as mentioned above for correct speed readings. Geoff Coppa, Kalgoorlie, WA. gen lighting is its suitability for focusing, highlighting, and creating a modelling effect by washing part of a wall or by picking out a particular object. By comparison, fluoro lighting is flat, featureless and ugly. This is because, in order for fluoro lighting to obtain sufficient output, the surface area of the fluorescing material needs to be quite large; it is impossible to produce a point source. A home lit with fluorescent lighting looks very cold and uninviting and while environmentally sustainable living is a worthy goal, life is also about aesthetics. Call me selfish but I am not warming to the idea of living in a home that has the atmospherics of a public toilet, a morgue or an interstate truck stop. Justin Wearne, Chatswood, NSW. siliconchip.com.au Atmel’s AVR, from JED in Australia CFL ban might have unforeseen effects I thought you might like to have this picture of my husband who is a regular reader and fan of your magazine. He is a US Navy-trained Electronic Technician, Water Service Electrician and member of IICA (Institute of Instrumentation Control and Automation). I bought this lamp home to use for sewing and study and I thought it ironic that he happened to be reading your April edition with the headline “Govt to Ban Incandescent Lamps?” Incandescent Madness perhaps? Jan Cowan, Westfield, WA. Comment: we know the government is mad. We hope it is not affecting any of our readers. Disable the XP firewall! I have built three USB ECG kits and all work very well on all versions of XP. However, you must disable the XP firewall then load your software, or it will not work! Peter O’Brien, Toowoomba, Qld. Comment: be sure to close down your Internet connection before disabling the firewall. Artificial barriers to electricians I am writing this letter in response to the comments in Mailbag (March 2007) with regard to electrical licensing and the related bureaucratic mess. Electrical licensing and its related bureaucratic management employ many people right across Australia. Electrical contractors and electricians contribute fees each year to sustain this level of administration. Through the use of electrical safety as a vehicle, they have created what appears to be an anti-competitive closed shop environment. Safety is an important issue in all facets of life, however it is itself more often a victim of exploitation through regulation, fees and profits. Unions are also important to us all, however some industries are over protected, while other workers in other areas are left siliconchip.com.au JED has designed a range of single board computers and modules as a way of using the AVR without SMT board design out in the cold. I would love to be a member of the ETU, however breaking into the electrical club is like getting into Fort Knox. Quality of work is the key, not tradespeople hiding behind a ticket. However, I don’t see anything changing while certain government agencies and organisations benefit from the license fees, permits, memberships and training. Many countries, including countries with 240VAC 50Hz, allow homeowners to take part in wiring their own homes. However because some Australians insist on special jobs for mates, tight regulation insures these regulatory desk jobs continue. The skills shortage is a myth. People do want to enter the trades but the artificial barriers work too well. The requirements of new electrical apprentices with relation to mathematics is a blatant attempt to stifle the-would be sparkie. While not denying that mathematics skills are important in electrical work, they are exaggerated in the Systems Electricians Certificate III Course. I would be very surprised if even 20% of practising contractors could pass the maths exam that is expected of apprentices now. Rob Taylor, New Town, Tas. Comment: we hope to have more to say on this topic next month. 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 June 2007  7 Mailbag: continued Car roof fan cools the interior I want to propose a project for cooling a car when it is parked in the hot sun. I have already installed a fan on my car but I invite you to improve on the idea, maybe with thermal and optical night-time switching. Most new cars are designed without regard for our hot climate. The industry’s argument seems to be that since most cars are air-conditioned, and since there is always the option to wind down the windows, then there is no longer any need for permanent (flow-through) ventilation. The result is that few cars can be seen with (secure) fresh-air vents such as were common in the 1970s and parked cars are now frequently steel coffins for abandoned children. I used a circle cutter to make a 75mm diameter hole in the roof of the car to fit a standard rally car passive flow-through creating ventilator. I also fitted a standard 12V 83mm 1.4W (120mA) computer fan directly under the metal car roof. The fan has a master switch but unless the fan is excessively noisy (in the quiet of night), it can be simply left running for days. This is because I also run the +12V power-in from the cigarette lighter (under the floor carpet) through to a “Projecta” brand Comparing hydrogen and helium In your March edition Mailbag, Bear Stanley made some incorrect statements regarding helium versus hydrogen in balloons: Hydrogen is one thirteenth the density of air (hydrogen is 0.09kg/m3 and air is 1.2kg/m3). Helium is one-seventh the density of air at 0.18kg/mm3. Just because helium has double the density of hydrogen does not mean it has half the lifting force. The actual lift is: Density of air - Density of lifting gas. For hydrogen the lifting force is 1.2 - 0.09 = 1.11kg/m3. For helium the lifting force is 1.2 - 0.18 = 1.02kg/m3. So hydrogen only has 9% more lift. Hydrogen gas is definitely not safe; 8  Silicon Chip battery discharge protector to make sure that the car will always have enough battery charge to start. My only regret is that the “Projecta” device seems to use as much power as the fan itself! (There is also the option to power the fan with solar cells). The car was a 1975 VW Passat Wagon fitted with just one vent in the roof and the windshield was shaded with a folding internal aluminium reflective sunshield; all other windows were shaded with “magnetic” see-through sun screens. Simply fitting the roof ventilator without the computer fan gives a thermal improvement equivalent to leaving a window slightly wound down – but without the security problems (and risk of a fine in Queensland). About two weeks ago on successive similar very hot days at around 1:30-2:30 pm, the car was parked in the same exposed place for one hour. If the computer fan was running, then the car’s internal temperature with a small leak and a spark it will burn just like the Hindenburg. Helium is much safer. Both hydrogen and helium have very small molecules so will escape very easily at about the same rate. Peter Kay, via email. The spark that changed the world I refer to Kevin Poulter’s article titled “The Spark That Changed The World”. I would like to bring to your attention an historical error on page 59 in the March 2007 edition. Radio station 2MT, better known as “two emma tock”, was situated in Writtle, near Chelmsford, Essex, close generally reached 40-42°C but on similar days when I neglected to turn on the fan, the interior temperature invariably exceeded 48°C. Since heavier cold air falls, then a roof ventilator should not cause problems for air conditioners. Since a parked car will be cooler, then air-conditioning heat loads (and fuel consumption) will be reduced. In previous winters, I found no (warmth) advantage in blocking off the roof ventilator. In fact, having (active) ventilation seemed to reduce the amount of window fogging. Michael Katalinic, Albury, NSW. Comment: we think that few people would want to cut a hole in their car’s roof to fit such a ventilator and fan. We also think that the fan’s current drain could be a serious problem. However, since all cars have airconditioning or a heater at least, it occurs to us that a neater approach would be to switch on the car’s interior aircon fan whenever the interior exceeds (say) 35°C. The fan could be controlled by a temperature switch and run at its lowest speed to minimise current drain. Ideally, it would be run from a separate battery to avoid the risk of over-discharging the main battery. A solar panel to charge it could complete the concept. The main difficulty with this approach would be to gain access to the fan’s wiring. to the home of Marconi’s wireless factory. Writtle is about 50km north-east of London and provided a dreadful signal east of the Thames. 2MT was the first regular broadcaster in the UK and was operated, designed and owned by the Marconi Wireless Telegraphy Company, under the leadership of Captain Peter Eckersly. The first regular broadcasts began in February 1922. The British Broadcasting Company, long since the British Broadcasting Corporation, did indeed begin regular broadcasting on November 14th, 1922 not from London but from station 2LO situated in Marconi House, Marconi’s head office building. It might have been appropriate to have mentioned the pioneering work siliconchip.com.au and discovery of Heinrich Hertz, who first observed and demonstrated the existence of electromagnetic radiation (radio waves) with a transmitter and receiver during the latter 1880s. Victor G. Barker, Gorokan, NSW. Dimmable CFLs are now available I read your April 2007 article about the government’s proposal to ban incandescent lamps with great interest. The article noted that dimmable compact fluorescent globes are not available in Australia! This is not true as I have two operating in my house to test how well they function. There is an outlet in Melbourne called “The Environment Shop” that sells energy-efficient household electrical goods. The two globes I have work quite well, the only drawback being that they don’t dim down as far as an incandescent would. A lower wattage globe would remedy this problem, as they are quite bright when they have warmed up. The banning of incandescents would also force industry to come up with solutions to the many different shapes and types of globes and fittings. Hopefully, LED globes will be mature enough at this point to be installed in smaller fittings. Alternatively, cold cathode fluoros that can be dimmed, and with a coiled tube design, could be installed in the tighter spaces. In the end, I’ll admit that it is unlikely that all incandescents can be totally replaced, particularly when it comes to environmental extremes such as inside an oven or that that this will make a significant impact on the greenhouse problem. However, if there is no outside force pushing change, how can anyone expect progress? Stefan Lacombe. Melbourne, Vic. Comment: we understand that dimmable CFLs are now available from Bunnings stores. Assisting hearing aid users with TV listening I have read with interest some of the comments about assisting those with hearing problems to enjoy listening to TV. Many hearing aids have a “T” switch which connects an induction siliconchip.com.au loop in place of the microphone so that they can “hear” a telephone conversation via the coil placed in most telephone receivers. This capability is used in many places where an inductive loop is installed around a room, such as in a meeting hall, and driven from a PA system so that hearing aid users can hear clearly via the loop. I have installed a small loop around the base of the lounge where my father, who uses a hearing aid, usually sits to watch TV. This is a single loop of 4-core telephone cable (non-twisted) with the four wires connected to form a 4-turn inductor. This is driven by a small amplifier module obtained from WES Components and which is mounted in a diecast box for heatsinking purposes. I drive this from the line level output of the TV. Results are excellent and all watching TV can have the volume at a level comfortable for themselves. One point to watch is that some TVs do not always put out a signal from the line level output with some input selections. Roger Woodward, Blakehurst, NSW. Modification to PIR sensor lights Concerning the problem of movement-sensor lights staying on due to intermittent power glitches (Ask SILICON CHIP, May 2007, page 97), the best answer is to install a standard On-Delay timer with 240VAC operating voltage, set to about five seconds delay. The timer will drop out on any power glitch and not come on again until the power has been steady for the delay period. These units are available at any of the electrical trade supply places. The in-built relay in the timer will handle the rating of the light. Mount it in a waterproof Clipsal plastic box, along with a light switch either on the box or in a convenient spot connected to the light side of the timer circuit to switch the light on permanently when required. Please note that this will almost certainly constitute “permanent wiring” and should be done by a licensed tradesman. Rod Cripps, Parkdale, Vic. At last, an alternative... ...designed especially for electronics professionals. Introducing the new U1252A DMM from Agilent Technologies, the world leader in Test & Measurement. The U1252A comes with... - Dual simultaneous measurements - 4.5 digit resolution on both displays - 0.025% Basic DCV accuracy; True RMS AC measurements - Dual temperature; Capacitance 10nF to 100mF - 20MHz Frequency Counter; Maths Functions - Programmable square-wave generator - Rechargeable battery, backlit LCD display - Free PC connectivity software for data-logging (optional cable required) - Built tough and reliable - Calibration certificate included - 3 year Australian warranty ...and at a very affordable price! Model U1251A Model U1252A $586 + GST $641 + GST Download product brochures, view online demos, and purchase online at www.measurement.net.au. Agilent’s new handhelds are distributed Australia-wide by Measurement Innovation. Tel: 1300 726 550 www.measurement.net.au info<at>measurement.net.au June 2007  9 VAF’s new Soundwall: by Ross Tester The speaker is history Spot the speakers in the above home theatre photo. Can’t see them? Think they’re Gone With the Wind? You’re right: they are! S cheduled to begin shipping in the USA very soon (and available here in Australia shortly after) is a revolutionary new product from Adelaide-based VAF Research. It’s difficult to describe it as a speaker, because that instantly evokes images of the ubiquitous box in the corner of the room or on the bookshelf. And those images would be plain wrong! But a speaker it most certainly is – it’s just not a “conventional” speaker. We’re talking about VAF’s new Soundwall. It combines art, interior design and architecture – along, of course, with some pretty advanced technology. For a start, there’s the size – each Soundwall module is 600mm square and just 120mm thick. It doesn’t sit on the floor or shelf; instead it (or more likely they) mounts direct to a wall, eliminating clutter and more than likely creating a visual statement in its/their own right. Second, each Soundwall module is powered by a digital 10  Silicon Chip amplifier rated at better than 150W RMS. Therefore in a simple, two-panel (stereo) installation there is more than 300W available; in a 7-channel surround-sound system that increases to more than 1000W! Both balanced and line-level inputs are provided, making the Soundwall compatible with “just about any” home theatre component available today or tomorrow. Soundwall performance is right at the “hi” end of hifi, with a response from 35Hz to more than 20kHz (±2dB) and, importantly, extremely wide dispersion – with ±3dB from on-axis out to 45° off axis (vertical or horizontal) over most of the frequency range. Incidentally, an unpowered version of the Soundwall, which can connect to almost all current hifi and home theatre amplifiers, is already available in Australia. Improves room acoustics Each SoundWall Acoustic Treatment Module contains siliconchip.com.au separate part of that immortal scene from the movie – and the result is simply stunning. It’s not just for home theatre use that the VAF Soundwall is finding willing new users: everything from the boardroom to clubs, indoor sporting venues, art galleries . . . in fact, the list is unlimited. Architects and interior designers are going ga-ga over them because they virtually become part of the wall (in fact, you can fill a wall with Soundwall modules if you want!). But more than that, the flexibility of being able to colour or even print the front “panel” of each Soundwall means that the designer can either match or complement existing colours and decors, or even make the speakers into the focal point of a room. VAF claim the Soundwall system is very easy to install due to a self-aligning mounting system, fewer connections and in-built cable management. If you decide later that you want to add to or modify your Soundwall, that’s simple too. Every Soundwall is packaged with a mounting system allowing installation on a timber, brick, plaster or SC plasterboard wall. For more information, contact VAF Research, 52-54 North Terrace, Kent Town SA 5067 Phone (08) 8363 9996; Fax (08) 8363 9997; or via their website: www.vaf.com.au The Soundwall basic colour is black or white but the front “panel” comes off, to be painted or printed with what ever you like! Here a 3 x 3 Soundwall has a plasma TV mounted in front. a combination of a “quadratic residue diffuser” and an “acoustic attenuator”. These provide the ability to both scatter room reflections and absorb them. Sophisticated response equalisation and active crossovers are used to ensure the best control possible and far greater freedom from distortion. Extended low frequency response ensures that substantial installations, including large-scale home theatre systems, can be created without the use of additional subwoofers. Any Soundwall combination is possible to suit virtually any application, from a single speaker module to act as a surround channel speaker, through to an entire wall surface combining ATM’s (Acoustic Treatment Modules) as well as Speaker Modules for stereo or surround sound. In VAF founder and managing director Philip Vafiadis’ words, the powered speaker module makes sound, while the acoustic treatment module fixes sound. It “repairs” room acoustics, making the Soundwall something that has to be experienced to be believed. Just imagine, if you will, a large-screen Plasma TV occupying centre-space of a home theatre system. Now imagine behind that Plasma TV, a whole wall of VAF Soundwall modules. Talk about a new meaning to “home theatre experience” – audio performance would arguably exceed that of the best theatres with banks of speakers mounted behind the screen. And even if you frankly, my dear, don’t give a damn, check out the photo of VAF’s “Gone with the Wind” Soundwall installation of 7 x 3 modules occupying a whole living room wall. Each Soundwall module is printed with a siliconchip.com.au This 5 x 3 Soundwall Module installation makes a real statement! And with more than 2kW of audio power available that statement is certainly going to be heard! June 2007  11 GIVE ’EM A Concluding our Turntable Review – this month we look at some of the software you’ll need to clean up that old vinyl and save precious memories to CD. I n digitising your old LP record audio tracks you don’t and won’t get very far without some processing software. Even a humble freeware application (and there are countless examples of those available to download) can make a phenomenal difference: remove the clicks from a vintage LP and you think you’ve solved one of life’s eternal mysteries. This is by no means an exhaustive list – Google “recording LPs” and you’ll get more than a million hits – but the software here is either packages we’ve used and liked or has been recommended by those “in the know.” We would have liked to include more but some software suppliers don’t know when an offer of free publicity jumps up and slaps them in the face . . . Windows Software: Express RIP This lets you extract digital audio tracks directly from audio CDs to either WAV or MP3 files on your hard drive. A free application, it’s offered “in the hope you will like it so much you will consider purchasing Express Rip Plus which offers additional features for the audio professional like more file formats and automation tools.” www.nch.com.au/software Wavepad An easy-to-use recorder – and it’s also free. It can record, edit and save your music. www.nch.com.au/ wavepad/masters.html Wave Corrector The program will automatically listen to your LP and break it up into individual WAV files for you. You can then do whatever you like with the tracks: resample them, clean them up with other signal processing programs or even make a backup copy of your vinyl or cassettes onto a CD. The latest release even allows you to compress to formats such as MP3 onthe-fly while recording. £6.00. www.ripvinyl.com This is a really neat tool which records and does a quick and thorough job of removing the crackles, hiss etc. You can download the demo to test it, but you’re limited to two minutes of music. Wave Corrector can rejuvenate your old analog recordings before transferring them to CD; it de-clicks vinyl; dehisses tape; reconstructs the original audio wave from measurements of the phase and frequency content; has a range of filters, track editor. £28. www.wavecor.co.uk/ DePopper LP Ripper 7.1.1 RIP Vinyl Removes crackles and pops caused by scratches and wear on vinyl. $US10. www.droidinfo.com/software/depopper/ WAV2MP3 Converts between WAV and MP3 formats. Free. wav2mp3lame.sourceforge.net/ 12  S 12  Silicon ilicon C Chip hip Makes the task of converting vinyl LPs, tapes and cassettes to MP3 files or CDs much easier. Record each side of the LP as a single WAV file on your computer. LP Ripper automatically splits the file into separate WAV files for each track. It can also use an MP3, WMA or similar encoder to produce a separate compressed file for each track. You can listen to previews of tracks and visually trim the start and finish. $US34.95. www.surfpack.com/software/vinyl/ siliconchip.com.au SPIN! Part 2 by BARRIE SMITH Because exchange rates vary so much, any prices quoted have been left in their original currency (eg, $US or £, etc) as quoted on the respective websites. To convert to $AU (or $NZ) with an up-to-the-minute exchange rate, log onto a currency conversion site such as www.xe.com Nero 6 Ultra Edition A suite of applications, also includes two audio-editing applications. With some components you can trim graphical WAV files, apply effects, normalise volume and the like, then splice together audio files, listen to effects, EQ and volume changes in real time and non-destructively. Nero Mix, is an MP3 player/ ripper/burner. $107 downloaded version; $153 boxed version. www.zdnet.com.au; www.nero.com Spin It Again Spin It Again records any vinyl LP or cassette to CD. Not only will it make the whole recording and track dividing process much easier but it will also dramatically clean recordings by getting rid of click and pop noises on records or by removing hiss and hum off old cassette tapes. $US34.95. www.acoustica.com/spinitagain/ Easy Hi-Q Recorder Version 2.0 Record any sound in real-time, directly to MP3, (CBR or VBR), WMA 9, (Windows Media Audio 9), WAV or OGG Vorbis. At the high-end you can record to above CD quality 48kHz stereo and at the low-end record all the way down to 8kHz mono. A very wide range of MP3 bit-rates, also for WMA, from 5 to 320Kbps. Also use it as a universal audio or video sound file converter. $US29.95. www.roemersoftware.com/ LP Recorder LP Recorder records vinyl to CD-standard WAV files for subsequent conversion to MP3 files or stored on CD. Special features suited to recording vinyl to WAV files include: automatically adjusts optimum recording levels to avoid distortion, auto start and auto stop for easy operation. $US34.95. www.surfpack.com/software/vinyl/ siliconchip.com.au Polderbits Sound Recorder and Editor Create CDs from vinyl; removes clicks, pops and crackle; reduces noise from tape recordings; employs equaliser to enhance overall sound quality; converts files from MP3 to WAV and vice versa; split recordings into multiple tracks. $USS36.50. www.polderbits.com Sound Forge Audio Studio Quite an act! This is an easy-to-use home version of Sound Forge professional software — “the industry standard for audio editing and mastering on the PC platform.” You can import analog audio, ready for further treatment. You enjoy pro-level control over audio editing, EQ, volume, and effects processing; mix audio tracks, balance sound levels, and create custom fades. Save in popular formats including MP3, WAV, and WMA. Burn your own CDs, export to an MP3 player. $US69.95 www.sonymediasoftware.com/Products Sound Forge 8 Upper level, highly capable pro version of Sound Forge Audio Studio. $US299.96. www.sonymediasoftware.com/Products CEDAR Available as a range of AudioSuite plug-ins, the CEDAR Tools suite comprises seven advanced processes allowing users to eliminate a wide range of audio degradations from an even wider range of audio materials. The applications offer high-resolution processing. Worth a visit to the site to see how the pros do it! www.cedar-audio.com/ JJune une 2007  13 2007  13 Laser Turntable Mac Software: Amadeus II This is a disc-based sound editor and processor, with visual waveform editing, live recording, sampling, analysis, sound repair/ denoising tools, a parametric equaliser designed for restoring old vinyl recording, and other features. $US30 for Mac OS 9, OSX 10.2 through 10.4. www.hairersoft.com/amadeus.html The Analogue Ripper 2.0 This makes it possible to record to a Mac from cassettes, reelto-reel, VHS and other analog sources. It records direct to disc, includes features for breaking audio into tracks. $US29.95 for Mac OS X. www.hotwork.org/TAR/MainTAR.htmlGraphing This seems like an idea that has missed its time! The ELP Laser Turntable plays vinyl records with no direct contact with the records grooves. So, no contact – no wear! Instead of a needle, the laser stylus reads record grooves using light. It replays the sound in analog form, just as a conventional stylus would, with no digitisation of the audio signal. Starting list price: $US15,000. www.elpj.com Australian distributor: Ron Brain, Crudon, Victoria. ronbrain<at>labyrinth.net.au Peak LE Converts vinyl and tapes to CD. Change duration without affecting pitch, add mixes, cross fades. $US129. Mac OS 10.2x or later; Mac Universal. www.bias-inc.com Coaster 1.1.3 Oversees the recording process and has controls similar to a tape deck. Get your sound levels right, hit the record button and you’re off. Coaster can even sense silence between tracks and split automatically into separate sound files, allowing you to record a whole LP without having to be around. Freeware. www.visualclick.de/download/coaster.sit Roxio Spin Doctor 2 ADS Instant Music! A family of useful applications is marketed by Roxio. CD Spin Doctor 2, bundled with Instant Music (reviewed in this coverage) can be used to digitise analog audio from vinyl or tapes; you can define tracks, reduce noise and enhance sound quality with included filters. It can be bought as part of the Roxio Toast suite: $139. Bought separately: $US39.99. www.macmall.com.au/mall/customer/ www.roxio.com/enu/products/spindoctor  Record Your Old LPs and Cassettes to CD, MP3 or your iPod  Save music as MP3, WAV, WMA and AAC (iPod) audio formats  Burn professional quality CDs* Capture from any audio source: cassette, turntable, TV,  radio, DVD Mac Users can use Instant Music with Garage Band or  Sound Studio 2.1 Includes Nero Suite for PC Users. PC and Mac Models available. an Austirbaultior Distr RRP $134.95 02 9975 2900 www.conexus.com.au 14  Silicon Chip siliconchip.com.au siliconchip.com.au Manual Windows/Mac/Linux Software: The It’s often said about computer software that the better it ClickRepair A very useful, Australian-created application that is cross platform — Macintosh/Windows/Linux. It finds and repairs clicks and crackle in audio files obtained by capturing vinyl and 78 RPM records to digital CD format. It is not a filter; it searches the file sample-by-sample, and only changes those identified as being suspect. It is possible to operate automatically, or to intervene manually. Favoured detection and repair settings may be named and saved. $US25. www.maths.anu.edu.au/~briand/sound/ Audacity Audacity is an easy-to-use audio editor and recorder for Mac, Windows, Mac OS X, GNU/Linux, and other operating systems. You can use Audacity to record live audio, convert tapes and records into digital recordings or CDs; edit Ogg Vorbis, MP3, and WAV sound files; cut copy, splice, and mix sounds together; change the speed or pitch of a recording. Freeware. audacity.sourceforge.net On page 18, I take a closer look at one of the best pieces of hardware/software I’ve found for copying an LP to PC and ultimately to CD – ADS Instant Music. It’s an ideal choice if your PC lack a decent sound card and it suits Windows/Mac/Linux environments too! siliconchip.com.au is the less need you’ll have to read the manual. This also applies, in some degree, to audio gear but you will frequently find that possession of the manual goes a long way to understanding the functions of a tape recorder or the niceties of a turntable, such niceties as adjusting the weight of the tone arm. After hooking up the Dual 1010 turntable my generous friend had passed on to me I was delighted to find that the manual for it was available as a free download from Vinyl Engine (www.vinylengine.com) The manual used in the PDF file was not scanned at an optimum resolution — but it was usable! Vinyl Engine also carry manuals for tone arms made by EMI, Garrard, Goldring, Acoustic Research, Sony and many others. Some other sites that can help with owner and service manuals: www.stereomanuals.com/index.htm have copies of manuals for TEAC, TASCAM, Technics — and that’s just the ‘T’ listing! www.markglinsky.com/ManualManor.html is operated by Mark Glinsky under the banner of Manual Manor. Mark has manuals for all sorts of audio equipment, from recorders to equalisers to turntables and more. Ortofon’s Arkiv magnetic cartridge If you have an old turntable and cartridge, there is serious doubt whether it will be capable of doing a good job in tracking typical high-quality vinyl discs. The problem is that the stylus itself may be worn, which means that it will damage the record’s grooves if you continue to play it. Worse still, its suspension may have lost flexibility and its compliance, the ability to track the record groove, will have been seriously degraded. The result will be that it will distort on heavily recorded passages and may even jump out of the groove, causing further damage. The solution is to purchase a new stylus assembly, if one is available. Better still, you could consider Ortofon’s new Arkiv magnetic cartridge. Released this month, it has been specifically tailored for vinyl to digital transcription. The Arkiv has an elliptical stylus and a frequency response of 20-20,000Hz. The cartridge output is quite high 6mV/cm/sec which means that most preamplifiers will have more than adequate gain, allowing for improved signal-to-noise ratio when you dub disks to CD. The Arkiv is available in both Concorde full mount, for bayonet type tone-arms, (RRP $159.50) and the OM half-inch mount for fixed headshell tone-arms (RRP $98.40). For more information contact Matthew Hunter at Speakerbits – telephone (03) 9647 7000. Website: www. speakerbits.com; email mh<at>speakerbits.com June 2007  15 Cassette Decks Many of us have managed to acquire mountains of compact cassettes, often in parallel to our purchase of LPs. If your experience is similar to this writer’s, few of these are of sufficient quality to copy to CD. Not only is the quality in general down, compared to LPs, many of them have served duty in poorly maintained car players and suffered damage. You may however, have some personally recorded tapes of value: those made at a wedding ceremony, baby’s first words, some amateur singing etc. Whilst not of a high quality level the data on them is irreplaceable and worthy of preservation on CD. Few single box cassette players have a line out facility. So if you’ve already turfed the family cassette player, you’re up for a new one or a used model. Some of the manufacturers who still market cassette players that can output line level audio to an amp are listed below. They are: Denon, Marantz, Panasonic, Pioneer, Sony. Golden Ears If you want to head into headphone territory there is an abundance of good quality brands out there. Among them are Altec, Grado, Sennheiser, Sony. Prices run from just over $100 and up into the thousands. It’s probably best to avoid the wireless and infra red types; both tend to limit full range reproduction. Good fitting ‘cans’ are important. A good place to start is www.buyquick.com.au as well, of course, eBay (if you know what you’re looking for!). “MERLIN” Safe External Switchmode Power Supply Practical and Versatile Mini Broadcast Audio Mixer Broadcast Quality with Operational Features and Technical Performance identical to full sized Radio Station Mixing Panels Permanent Installation is not required, the “Merlin” is as easy as a Stereo System to “Set Up”,all connections via Plugs and Sockets The “Merlin” originally designed for Media Training use in High Schools and Colleges is a remarkably versatile Audio Mixer Applications: Media Training - Basic Audio Production - News Room Mixer - Outside Broadcasts - Radio Program Pre Recording On-Air Mixer in small Radio Stations - “Disco Mixer” The “Merlin” is an Affordable Professional Audio Product Buy one for your School, College, Community Radio Station, Ethnic Radio Broadcast Association or for yourself For Details and Price, please contact us at ELAN Phone 08 9277 3500 AUDIO Fax 08 9478 2266 2 Steel Court. South Guildford email sales<at>elan.com.au www.elan.com.au Western Australia 6055 16  Silicon Chip Vintage Speeds Rek-O-Kut distributor Decibel HiFi is adamant that when you play 78RPM discs “at their correct pitch, you will never be able to tolerate previous 78 turntables.” One of their models can also handle vertical cut discs, as made by the Edison and Pathé companies. At the time, early 78RPM discs varied from 62 to 94RPM. The Rek-O-Kut turntables can cope with this variation and offer continuously variable speeds in their range. Further, using a strobe, it is possible to set any of twelve speeds from 68.5 to 90RPM. Contact Details Denon, NAD: Audio Products ..............1300 134 400 www.audioproducts.com.au help<at>audioproducts.com.au Dual: AudioPhile......................03 9489 4864 www.audiophile.com.au info<at>audiophile.com.au Goldring: Duratone Imports...........02 6282 1333 www.duratone.com.au sales<at>duratone.com.au Moth, Rek-O-Kut: Decibel Hi-Fi..................07 3272 7660 www.decibelhifi.com.au enquiry<at>decibelhifi.com.au Optimus: Dick Smith Electronics...1300 366 64 www.dse.com.au Pioneer: Pioneer Australia...........1800 988 268 www.pioneer.com.au/product service<at>pioneer.com.au Rega: Synergy Audio Visual.....03 9416 4161 www.synergy-audio.com info<at>synergyaudio.com Panasonic: Panasonic Australia.......132 600 www.panasonic.com.au Pro-Ject: International Dynamics Australasia 03 9429 0822 www.internationaldynamics.com.au mail<at>internationaldynamics.com.au Sony: Sony Australia ...............1300 720 071 www.sony.com.au Stanton: Jands..............................02 9582 0909 www.jands.com.au info<at>jands.com.au Thorens: Hi Fi Junction ................02 9389 4000 www.hifijunction.com.au hifi<at>fl.net.au siliconchip.com.au siliconchip.com.au June 2007  17 Review: ADS Technologies “Instant Music” analog music to digital formats task fast and straightforward for Windows, Macintosh and Linux users, with the ultimate intention to burn your own CDs. If your ultimate venue is an iPod player, this gear will handle it. The base unit is a junction box that has a pair of stereo analog RCA inputs (and a pair of RCA outputs), along with optical digital SPDIF (Toslink) in/outputs. The interface with the computer is USB (1.0 or 2.0). You simply connect up the supplied USB lead between the junction box and a free USB port on your computer; set up your computer to ‘read’ the USB appliance — and your sound material can be transferred The Instant Music package includes all you need to digitise analog recordings into the digital realm of your with USB and RCA cables plus software for Windows and Macs. computer. Windows PCs will self detect the new appliance; drivers are built into every Windows n some ways this piece of gear is unnecessary – and version since Windows 98. If not, there are clear instrucin other ways, absolutely necessary. tions in a PDF file on the CD carrying the main software. Most people embarking on the good ship analog to Mac users will similarly find that their computer can be CD will connect the output of their amp/tape player or configured to ‘read’ the device via the “Sound” portion of record turntable (with preamp fired up) directly into the the System Preferences. sound input of their computer, with the analog-to-digital At this point let me make it clear that the unit will import conversion handled by the computer’s sound card. only two-channel (ie stereo) line level audio. If you hope to But there are some poor souls, especially the owners hook up a turntable and shuffle your Kamahl tracks over to of budget desktop and laptop models, who don’t have a the digital domain — forget it! You still need to route the sound input/audio card. If so, this device is perfect! audio via an amp or preamp to correctly feed the InstantInstant Music, by ADS Technologies, is an unusual Music appliance. package in more ways than one. It makes the converting I An explicit user interface makes the analog to digital dubbing process easy to work with. In the software department, Windows users get a copy of Nero Mix, SoundTrax and Wave Editor; Macanatics get a copy of Roxio Spin Doctor. 18  Silicon Chip siliconchip.com.au This gets the audio into your computer but you can’t do much with it. Software Both Windows and Mac versions of InstantMusic are bundled with software (Windows – Mix, SoundTrax and Wave Editor; Mac – Spin Doctor 2); if you already have a full version of Nero 6 or 7 you’re already up and running. Both of the bundled applications are audio recording programs, containing useful features to record, diminish/remove scratches, hiss and clicks, then polish The Instant Music device has a pair of stereo analog RCA inputs (and outputs), plus optical and even equalise (mod- digital SPDIF (Toslink) in/outputs. The interface with the computer is USB (1.0 or 2.0). erately) the incoming sound program. but it will never transform an aria by Caruso on an Edison The Windows/Nero bundle can be used to arrange tracks cylinder to rival the quality of a performance by Pavarotti into play lists, edit start/stop times or add a cross fade from on CD. But then again, who would want to? one track to the next for a smooth transition. With the stepSupplied accessories: Instant Music device; Roxio by-step wizard features, users can personalise their music Spin Doctor 2 or Nero Mix, Nero SoundTrax and Nero by selecting tracks, adding transition effects and, using the Wave Editor; USB cables; L+R RCA cable; RCA to 3.5 app’s equaliser, to set levels. mm stereo adaptor cable. The Audio Cleaning tools can be used to filter out unADS Technologies: www.adstech.com/ wanted pops, clicks and hisses. Distributor: Conexus — www.conexus.com.au Mac users can operate Instant Music with Garage Band Price: $134.95. SC or Sound Studio 2.1. Once captured - and all the spit and polish applied to your tracks – they can be saved as MP3, WAV, WMA (Windows Media 9 Audio) or AAC (iPod) audio files. If you have ambitions in cleaning up the original audio to higher standards you may need to interpose a multi-band equaliser into the plan or acquire some high-end software. As you are possibly becoming well aware, this whole exercise of transferring veteran analog music tracks to CD is a challenge – not only in devoting the time you can allot to the exercise but also in what finances you are courageous enough to invest. The bundled Windows/Mac applications are audio recording programs that Instant Music and the bundled record, reduce and/or remove scratches, hiss and clicks, then polish and even software does an incredible job equalise the incoming analog sound. siliconchip.com.au June 2007  19 20W Class-A Amplifier; Pt.2 This fully assembled chassis shows what the Stereo Class-A Amplifier will look like. The preamplifier/remote volume control module and the loudspeaker protection module will be described in following issues. In Pt.2 this month, we present the construction details for matching left and right channel mirror-image modules, together with the circuit and construction details of the power supply. Pt.2: By Leo Simpson 20  Silicon Chip siliconchip.com.au Fig.6: follow this parts layout diagram to build the left channel power amplifier module. Be sure to use the correct part at each location and make sure that all polarised parts (transistors, diodes and electrolytic capacitors) are correctly installed. T HE NEW PC boards are longer than the original SILICON CHIP July 1988 modules. This is mainly to spread the two power output transistors further apart on the large single-ended heatsinks. This has the effect of spreading the central hot spot produced by the original module and allows us to use the heatsinks more efficiently. This time around we have also designed mirror image PC boards, for the left and right channels. This has been done to achieve a better wiring layout within the amplifier chassis and also to optimise the residual noise performance in both channels. Both PC boards measure 146 x 80mm and are coded 01105071 (left) and 0110572 (right). To ensure reliable connections to the PC boards, we have specified chassis-mount QuickConnect single-ended male spade terminals which have a mounting hole for an M4 screw. These connectors are normally used for high current connections but we are using them here because we want to ensure very low resistance connections. They have the advantage over normal soldered connections to the PC board in that they can be repeatedly connected and disconnected without siliconchip.com.au problems, when an amplifier is being assembled and checked. By the way, we do not recommend staked Quick-Connect spade lugs for this application as they are not as reliable, particularly after they have been reconnected a few times. With the same thought in mind about reliable terminations, the audio signal connection to each module is made via an on-board RCA socket. This is much better than using soldered connections for shielded cable, as they are bound to look messy after being disconnected and reconnected just once. One module or two? Before we start on the assembly details, there are a few other points to note. The first pertains to whether you are building a single PC board module to be used as a mono amplifier (unlikely, but we have to consider it). If so, note that R1 is a 0W link, as shown on the circuit of Fig.5 in last month’s issue. Alternatively, if you are building left and right modules for a stereo amplifier, R1 must be changed to a 10Ω resistor (in each channel). This is done to reduce the possibility of circulating currents in the completed stereo amplifier which could compromise the performance, particularly separation between channels. Transistor quality To ensure published performance, the MJL21193 & MJL21194 power transistors must be On Semiconductor branded parts, while the 2SA970 lownoise devices must be from Toshiba. Be particularly wary of counterfeit parts, as reported by us in the past. We recommend that all other transistors used in this project be from reputable manufacturers, such as Philips (NXP Semiconductors), On Semiconductor and ST Microelectronics. This applies particularly to the BD139 & BD140 output drivers. The component layouts for the mirror reverse boards are shown in Fig.6 (left) and Fig.7 (right). Begin each board assembly by installing the wire links, the two 1N4148 diodes (D1 & D2), and the resistors and capacitors. The resistor colour codes are shown in Table 1 but we strongly advise that you also check each value using a multimeter before it is installed. Make sure that the diodes and elecJune 2007  21 Fig.7: this is the layout for the matching right-channel power amplifier module. It’s almost a mirror image of the left-channel board. trolytic capacitors are installed with the correct polarity. That done, you can then install the fuse clips. Note the each fuse clip has a little lug on one end which stops the fuse from moving lengthways. If you install the clips the wrong way around, those lugs will stop you from fitting the fuses. Next, install the two 0.1W 5W resistors followed by trimpot VR1 (this must go in with its adjustment screw oriented as shown). The small-signal (TO-92) transistors (2SA970s, BC546s & BC556s) can then be installed. As supplied, these transistors usually have their leads in a straight line, although the centre lead may sometimes be cranked out. They have to be splayed outwards and cranked to fit nicely into their allocated positions. The way to do this is as follows. First, grip the three leads adjacent to the transistor body using a pair of needle-nose pliers and bend the centre lead back and up by about 70°. That done, grip each of the two outer leads in turn and bend it outwards and up by about 70°. Finally, grip each lead in turn at the end of the pliers and bend it downwards again – see photos. Install each transistor on the PC Fig.8: follow this diagram to attach the BD139 and BD140 transistors to their respective heatsinks. Note that each transistor is electrically isolated from its heatsink using a silicone insulating washer. 22  Silicon Chip board after dressing its leads. Note that transistor pairs Q1 & Q2 and Q3 & Q4 are installed with their flats facing each other. Make sure that you don’t install the TO-92 transistors in the wrong positions. Inadvertently swapping 2SA970s for BC556s will not have any dire consequences, except that the amplifier will not be as quiet as it would have been. But swapping BC546 NPN transistors for BC556 or 2SA970 PNP transistors will cause serious damage when the amplifier is first powered up. You have been warned! The idea is to work carefully and This close-up view shows one of the BD139 transistors (left-channel amplifier board). A second BD139 mounts on the other side of this heatsink. siliconchip.com.au Follow this photo in conjunction with Fig.7 when building the right-channel amplifier module. Note that the output transistors (Q12 & Q14) must be electrically isolated from the heatsink using thermal washers (see Fig.9). patiently through the assembly process. Check each step against the diagrams and photos as you go. Care and patience now will be rewarded later when you turn the amplifier on. The TO-126 transistors Q10, Q11 & Q13 are fitted to U-shaped flag heatsinks before they are soldered to the PC board. More specifically, Q10 and Q11, both BD139s, are mounted on opposite sides of the same flag heatsink (see Fig.8) while Q13, a BD140, is mounted on a separate flag heatsink. Note that each transistor must have a silicone rubber pad to isolate it from the heatsink – see Fig.8 and the photos. Note also that the 100pF ceramic capacitor at the collector of Q9 should be an NPO type (ie, with zero temperature coefficient). NPO capacitors have a black spot or strip across the top. If your 100pF capacitor does not have this black labelling, it is not NPO. siliconchip.com.au Other types may change their capacitance markedly with temperature, which is undesirable. Winding jig The next step is to wind the 6.8mH inductor. To do this, you need about 1.5m of 1mm enamelled copper wire which is close-wound onto a plastic bobbin. This bobbin may have an in- ternal diameter of either 11.8mm or 13.8mm, depending on the supplier. As shown in the photos, we made up a small winding jig for the bobbin, as this enables a really neat job. It consists of an M5 x 70mm bolt, two M5 nuts, an M5 flat washer, a piece of scrap PC board material (40 x 50mm approx.) and a scrap piece of timber (140 x 45 x 20mm approx.) for the handle. The leads of the TO-92 transistors are cranked to fit the PC board using a pair of needle-nose pliers. These photos show how it’s done. June 2007  23 ➊ ➋ ➌ ➍ Above: these photos show how to make a simple jig from scrap material to wind the 6.8mH inductors (see text). First, the bobbin is slipped over the collar on the bolt (1), then the end cheek is attached and the wire threaded through the exit slot (2). The handle is then attached and the coil wound using 25.5 turns of 1mm enamelled copper wire (3). The finished coil (4) is secured using a couple of layers of insulation tape and a band of heatshrink tubing. In use, the flat washer goes against the head of the bolt, after which a collar is fitted over the bolt to take the bobbin. This collar should be slightly less than the width of the bobbin and can be wound on using insulation tape. Wind on sufficient tape so that the bobbin fits snugly without being tight. Next, drill a 5mm hole through the centre of the scrap PC board material, followed by a 1.5mm exit hole about 8mm away that will align with one of the slots in the bobbin. That done, the bobbin can be slipped over the collar and sandwiched into position between the washer and the PC board (which acts as an end cheek). Align the bobbin so that one of its slots lines up with the exit hole in the end cheek, then install the first nut 24  Silicon Chip and secure it tightly. The handle can then be fitted by drilling a 5mm hole through one end, then slipping it over the bolt and installing the second nut. Winding the choke Begin by feeding about 40mm of the wire through one of the bobbin slots and the exit hole in the jig (loosen the handle if necessary to do this). Bend this end back through 180° to secure it, then tighten the handle and wind on 25.5 turns as evenly and tightly as possible. Finish by bending the remaining wire length through 90° so that it aligns with the opposite slot. The windings can now be secured using a couple of layers of insulation tape, after which the bobbin can be removed from the jig. Cut off the excess Here’s another view of the fullyassembled right-channel power amplifier module, attached to its heatsink. After mounting the output transistors, it’s a good idea to use a multimeter (set to a high ohms range) to confirm that they are correctly isolated from the heatsink. You should get an open-circuit reading between the heatsink and each of the transistor leads. siliconchip.com.au Fig.9: this diagram shows the mounting details for the output transistors (left), along with the heatsink drilling diagram (above). Note that the transistors are mounted with a lead length of 9mm using the method detailed in the text. Be sure to deburr the mounting holes using an oversize drill, to prevent punch-though of the insulating washers. siliconchip.com.au June 2007  25 Fig.10: the power supply circuit uses a centre-tapped transformer with 16V windings to drive a bridge rectifier and six 10,000mF filter capacitors. wire at each end, leaving about 10mm protruding. Finally, complete the choke by fitting some 20mm-diameter (9mm wide) heatshrink tubing over the windings. Be careful when shrinking it down with a hot-air gun though – too much heat will damage the plastic bobbin. You can now test fit the finished inductor to its PC board, bending its leads as necessary to get the bobbin to sit down flush on the board. It’s then just a matter of stripping the enamel from the wire ends and tinning them before soldering the choke in place. Power transistors The two output transistors must be installed with their plastic bodies exactly 9mm above the surface of the PC board. In practice, you have to first mount the two transistors on the heatsink. Fig.9 shows the mounting details for each device. Note that it is necessary to use a thermal insulating washer to electrically isolate each device from the heatsink. First, check that the mounting areas are smooth and free of metal swarf (deburr the holes if necessary using an oversize drill), then loosely secure each device to the heatsink using an M3 x 20mm machine screw, flat washer and nut. That done, cut a couple of 9mm wide cardboard spacers about 40mm long – these will be used to space the transistor bodies off the PC board. Next, turn the heatsink assembly upside down and slip the PC board (upside down) over the transistor leads. Push the board down so that the cardboard spacers are sandwiched between the board and the transistor bodies, then line everything up square and lightly tack solder the centre lead of each device. It’s important to now check that everything lines up correctly. The PC board should sit exactly 10mm below the edge of the heatsink, while each end of the board should be 77mm from its adjacent heatsink end (it helps to mark these points beforehand). Make any adjustments as necessary, then complete the soldering and trim the device leads. That done, you can tighten the mounting screws that secure the transistors to the heatsinks, making sure that the insulating washers are correctly aligned. These screws should be tight to ensure good thermal Table 1: Resistor Colour Codes o o o o o o o o o o o o o o No. 1 4 3 1 1 1 1 1 8 3 1 1 1 26  Silicon Chip Value 1MW 10kW 2.2kW 2.2kW 1W 5% 1kW 680W 510W 270W 100W 68W 16W 10W 1W 5% 6.8W 1W 5% 4-Band Code (1%) brown black green brown brown black orange brown red red red brown red red red gold brown black red brown blue grey brown brown green brown brown brown red violet brown brown brown black brown brown blue grey black brown brown blue black brown brown black black gold blue grey gold gold 5-Band Code (1%) brown black black yellow brown brown black black red brown red red black brown brown NA brown black black brown brown blue grey black black brown green brown black black brown red violet black black brown brown black black black brown blue grey black gold brown brown blue black gold brown NA NA siliconchip.com.au The power supply module carries the six 10,000mF 35V filter capacitors plus two LED circuits to indicate that the supply is working correctly. Fig.11: here’s how the build the power supply board. Install the Quick-Connect terminals first so that there’s no risk of damaging the expensive 10,000mF capacitors if a tool slips while tightening the screws. The capacitors can then go in, followed by the resistors and the LEDs. coupling between each device and the heatsink. Finally, check that each device is electrically isolated from the heatsink using a multimeter. You should get an open-circuit reading between each device lead and the heatsink metal. By the way, we recommend highefficiency thermal insulating washers for the MJL21193 & MJL21194 output devices (see parts list last month). Typical low-cost silicone rubber wash­ers performed poorly in our lab tests, resulting in at least 5°C higher transistor running temperatures. On a similar theme, adequate airflow siliconchip.com.au up through the heatsink fins is vital to amplifier survival and long-term reliability. This means that the amplifier must be operated in a well-ventilated area – those heatsinks do get hot (typically 30°C above ambient). That completes the assembly details of the power amplifier modules. Next, we need to discuss the power supply circuit and construction of the power supply module. Shielded power transformer As noted last month, this new design dispenses with the regulated power supply and uses a bridge recti- fier and a bank of filter capacitors. Fig.10 shows the circuit. As can be seen, it employs a centre-tapped transformer with 16V windings to drive a bridge rectifier and six 10,000mF 35V electrolytic capacitors (30,000mF on each side) to provide balanced ±22V DC supply rails. Also included in the power supply circuit are two LEDs and two 2.2kW resistors to provide a visible indication that power is present on the supply rails. This is very handy when you are working on the amplifier. Finally, there are two 100nF MKT polyester continued on page 30 June 2007  27 Measuring Ultra-Low Harmonic Distortion How good are our new Class-A audio amplifier modules? Well, they are too good to measure on our Audio Precision test gear, as we shall see. Back in 1998 in the class-A amplifier article, we noted the great difficulty in measuring the very low distortion of the circuit. The main problem is that, at lower power levels, circuit noise tends to completely obliterate the measurement. Even at full power (20W), the noise in the signal is quite significant. To put that into perspective, the signal to noise ratio of the new amplifier with respect to full power is -115dB unweighted (ie, with a noise bandwidth from 22Hz to 22kHz) which is very, very low. How low? Think of a noise signal which is only 22 microvolts! Compare that with the total harmonic distortion which is typically .0006% (-104dB or 76mV) and you can see that noise is a significant part of the measurement. In the July 1998 article we demonstrated a method to remove the noise component of a THD (total harmonic distortion) signal using the averaging feature of a Tektronix TDS360 digital scope. The noted audio designer, Douglas Self, devised this method. This technique can filter out virtually all the random noise signal to leave the harmonic content displayed. Fast-forward nine years to June 2007 and we can do the same procedures using our vastly more capable LeCroy WaveJet 2Gs/s 200MHz digital oscilloscope. We often feature screen grabs from this scope to demonstrate circuit performance. However, the LeCroy WaveJet does not allow us to perform normal sampling and averaging on the same signal simultaneously and we wanted to do this in order to more clearly demonstrate the dramatic effect of noise averaging using a digital scope. What to do? It turns out that LeCroy have a much higher performance scope which would let us do this procedure. So, thanks to Charles Holtom of Trio Smartcal (phone 1300 853 407), we managed to gain access to a LeCroy WaveRunner 10Gs/s 600MHz scope. We performed three tests to dem­ onstrate the extremely high performance of our new amplifier. The accompanying three scope screen grabs each show three signal traces. In each case, the top trace is the fundamental – ie, a 1kHz sinewave. The trace below that is the residual THD signal after the fundamental Scope1: the THD measurement of the amplifier at 1kHz and 20W. Note the much cleaner averaged bottom trace (green). 28  Silicon Chip siliconchip.com.au 1kHz sinewave has been nulled out by our Audio Precision automatic distortion test set. Both these traces are displayed using normal scope sampling so all the noise in the signal is clearly shown as a large random component. The bottom trace is displayed using the averaging technique and is in fact the average of 128 sweeps of the trace. Furthermore, we have applied a degree of digital filtering to limit the noise in the displayed signal. Scope1 shows the measurement of the new amplifier at 20W. The total harmonic distortion was .00056%. To explain this, the middle trace represents an RMS voltage which is .00056% of 12.69V, the signal level needed for 20W into an 8-ohm load. As presented on the scope, the middle trace has a mean (ie, average) value of 4.54mV RMS. Now look at the averaged trace (bottom). Not only is it almost completely devoid of random noise (revealing the true harmonic content) but its RMS value is only 1.96mV RMS. This enables us to recalculate the true harmonic dis- This photo shows the prototype modules under test using the LeCroy WaveRunner scope and our Audio Precision test set. These tests also allowed us to optimise the wiring layout in the test chassis. tortion to be around .00024%! Wow. By the way, the scope displays a full set of measurements for channel 3 (blue) and channel 4 (green), including instantaneous value, mean, min, max and standard deviation. Scope2 is even more dramatic as it demonstrates the THD measure- ment at a power level of 1W. Here, the measurement is .001%, much worse than for full power but in this case the fixed residual noise level of around 22mV is much more significant compared to the THD residual which is 56mV. In this case, the THD . . . continued next page Scope2: the THD measurement of the amplifier at 1kHz and 1W. Here the residual noise (trace 2 – blue) is much greater and the averaged trace (green) is much cleaner. siliconchip.com.au June 2007  29 Scope3: the THD measurement of the Audio Precision test set at 1kHz and 600mV. Measuring Ultra-Low Distortion: continued from previous page trace is 2.2mV RMS compared to the averaged trace (bottom) of 531mV. Recalculating the harmonic distortion in the same way again gives a result of .00024%. This clearly shows that the harmonic distortion does not increase when the power level of the amplifier is reduced. Well, that’s great but it is not the whole story because when we measure the Audio Precision distortion test set itself, its THD is .0004% at 1kHz at a level of 600mV. Scope3 shows the equivalent process and after averaging the harmonic distortion, the reading is capacitors to provide a high frequency bypass filter on each supply. However, the real feature of the power supply is the magneticallyshielded toroidal power transformer. Most people would be aware that standard toroidal power transformers have quite a low leakage inductance and therefore little hum radiation 30  Silicon Chip .00024%. But isn’t that the same as the above readings for the amplifier? Yep. So in fact, we don’t know how good the amplifier really is. Based on these figures, it might be less than .0001% but we have no way of knowing. As a further exercise, we were able to do spectrum analysis using the LeCroy WaveRunner’s FFT facility. However, while that showed the first harmonic content at down below .0001% for the Audio Precision’s generator and similar low figures for the amplifier, the tests simply did not let us make any further estimates. By the way, measuring a level of .0001% with respect to a 600mV signal actually refers to a signal comwhen compared to conventional EI laminated transformers. That is correct but the hum radiation from a standard toroidal power transformer is still not low enough when used in conjunction with these high performance class-A amplifier modules, as we found with our 1998 design. Because of the constant power ponent of just 6mV. The FFT analysis was able to measure harmonics out to the 19th, at much lower levels, so we were looking at harmonic components as little as -130dB with respect to the fundamental signal level. This is far below the amplifier’s residual noise level; such is the capability of the LeCroy WaveRunner oscilloscope. It has 11-bit precision, enabling accurate measurements even at just a few microvolts. So when you look at the overall harmonic distortion figures published in Pt.1 (and to be published in future months for the completed stereo amplifier) remember that they don’t tell the true story. This amplifier is actually too good for us to measure properly. demand of about 100W drawn by the two modules, the transformer still has quite a significant hum field and this is a real problem when it is operated in close proximity to the amplifier modules. Our solution in the 1998 design was to use a separate power box, to keep the transformer well away from the modules. siliconchip.com.au This life-size view shows the fully assembled left-channel amplifier module. Note that some minor changes were made to the PC board (just to the right of the RCA audio input socket) after this module was assembled This time around, we are specifying a shielded toroidal transformer, to keep the leakage inductance much lower. This employs a number of long strips of grain-oriented steel wound around the outside of the finished transformer and then covered in several layers of insulation. The unit looks just like any other toroidal transformer but the hum field is much lower. In addition, the transformer is oriented to give the best performance when it is finally installed in the chassis. As shown in the specifications panel last month, the end result is excellent, with extremely impressive signal-to-noise ratios and harmonic distortion figures. We will discuss this further in a future article. Power supply assembly The PC board for the power supply accommodates the capacitors, the siliconchip.com.au two LEDs, their resistors and that’s it. The 35A bridge rectifier mounts on the chassis which is necessary to remove the significant amount of heat produced by it. The power supply PC board is coded 01105073 and measures 135 x 63mm. As with the amplifier modules, all the connections to it are made via chassismount Quick-Connect male spade terminals which have a mounting hole for an M4 screw. Fig.11 shows the parts layout on the PC board. Install the Quick-Connect terminals first. As shown, three doubled-ended terminals are installed at the DC end of the board (ie, the same end as the LEDs), while three singleended termainals are installed at the bridge rectifier end. Once all the Quick-Connect terminals have been tightly secured to the PC board, you can then install the six PC-mount electrolytic capacitors. Make sure that you mount them with the correct orientation otherwise there will be an almighty bang when you first turn on the power! Finally, mount the MKT capacitors, the resistors and the two red LEDs. That’s it – the power supply board is complete. Next month Next month, we will describe the Loudspeaker Protector module, with the Preamplifier & Remote Volume Control Module to follow. And just in case you are wondering, the remote volume control will be achieved using a motorised pot and will work with a standard universal remote transmitter. In the meantime, don’t be tempted to power up the amplifier modules – there’s a set procedure to follow with regards to setting the quiescent current SC through each output stage. June 2007  31 SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: dicksmith.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: dicksmith.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: dicksmith.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: dicksmith.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: dicksmith.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: dicksmith.com.au 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. Simple battery isolator Over the years there have been a number of circuits used to charge and isolate a second 12V battery in a vehicle. The most recent of these was featured in Circuit Notebook in the March 2007 issue. This circuit is even simpler and employs a 6V feed from one of the stator connections on the vehicle’s alternator. This is connected to a 6V automotive relay (RLY1) which controls a Continuous Duty Solenoid (RLY2). This solenoid electrically connects or isolates the batteries. When the engine is started and the alternator stator voltage rises, the 6V relay turns on. This turns on the Continuous Duty Solenoid to connect the two batteries in parallel. As long as the engine is running, the vehicle’s alternator will maintain charge in both batteries. When the engine is shut down, the alternator stator voltage drops and the Continuous Duty Solenoid switches off, thus isolating the second battery from the vehicle’s electrical system. Provided that camping accessories are only connected to the second battery, the main battery should never discharge. Because the concept is entirely dependent upon the alternator’s stator output voltage, you cannot forget to turn the system on or off as it happens automatically. The system could also be modified to include an emergency engine start system if a separate switch is wired in to energise the Continuous Duty Solenoid from the second battery. If the original vehicle battery ever does become discharged and is unable to start the engine, this would allow the standby battery to start the engine. Once the engine is running, the switch can be released and the system will revert to normal operation. Connection to the alternator stator will mean disassembly of the alternator and although this is not difficult, care should be taken to ensure that when the two halves of the alternator body are separated, the stator leads are not stressed or broken. The insulated wire to the stator connection can be run into the alternator through one of the air vents and protected by a small grommet or fibreglass tubing. A fairly large soldering iron will be needed as the stator connection at the rectifier is mounted on a large heatsink. Care should also be taken on re-assembly, as some models of alternator require that the brushes be held back by a small pin prior to assembly. Without this pin, assembly will result in damage to the carbon brushes. Note that a Continuous Duty Solenoid must be used. Those intended for use with winches are for intermittent use and will burn out. Note: if this method of battery connection is employed, both batteries should have the same CCA rating or amp.hour rating. Some Bosch alternators already have a 6V single pin output connector on the rear of the casing. Its output can be confirmed with the careful use of a multimeter. Use extreme care when undertaking this test, as the engine must be running and there will be danger from spinning fans. Dave Sargent, Howard, Qld. ($35) 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. 38  Silicon Chip siliconchip.com.au Using the PICAXE in SPI mode Those readers interested in the Remote Volume Control project featured in the February 2007 issue will be interested in the fact that the PICAXE can use the SPI (serial peripheral interface) bus to manage the Burr-Brown PGA2310 stereo volume control IC, with the BASIC programming language. The digital circuitry is connected straight from the PIC18X to the PGA2310. Note that the SCLK, SDI and SDO pins must be connected as shown. Looking at pins RB1 and RB4, these are designated for SDA and SCL when the PIC18X is set to I2C mode. This is done within the BASIC command I2CSLAVE slave, speed, address and is used only once within the program. The same principle applies for initialising the PIC18X to SPI mode. It’s very simple to configure and execute the SPI bus within the program. It’s just a matter of using the POKE location, variable command to the registers but be careful to access the correct internal registers. It is necessary to first set the configuration register SSPCON (address = 14h) and SSPSTAT (address = 94h) to put pins RB1 (SDI), RB2 (SDO) and RB4 (SCL) into SPI mode, and set the timing waveforms. Note that the SPI Serial Clock output is set to 1MHz. The values to poke these registers are given in the sample but for more detailed information download the PIC16F88.PDF (PIC18X) from Microchip. Then to execute data transmission from the PIC18X SDO pin to the PGA2310, issue a POKE command with the required data to the register SSPBUF (address = 13h). Each POKE command issued to this register will send eight bits of data. To send 16 bits, use the command twice in succession and so on. This allows the cascading of multiple PGA2310 chips, to create volume controls for a 5.1 surround system. It is also possible to read the SPI bus data from the SDI pin, by issuing a PEEK command to the same register, SSPBUF (address = 13h). This can be used to confirm that the PGA2310 has received the new data. siliconchip.com.au 'Demonstration of SPI bus on the PIC18X, to control the PGA2310 symbol symbol symbol symbol symbol symbol mute SDI SDO CS SCL dB_Level = b2 Main: let pins = %00001000 pause 100 gosub config_SPI high mute let dB_Level = 0 up_loop: let dB_Level = dB_Level + 1 gosub Transmit if dB_Level != 255 then up_loop =0 =1 =2 =3 =4 Martin D is this m aines onth’s winne Peak At r of a las Instrum Test ent 'Pull CS high for it’s normal state 'Allow time for PGA2310 to power up 'Turn PGA2310 mute off 'Before this point you can read the SSPBUF register to comfirm change down_loop: let dB_Level = dB_Level - 1 gosub Transmit if dB_Level != 0 then down_loop goto up_loop end config_SPI: let b0 = 32 let b1 = 192 poke $14,b0 poke $94,b1 return Transmit: low CS poke $13,dB_Level poke $13,dB_Level high CS pause 400 return '00100000 '14h_SSPCON SPI enable' '11000000 '94h_SSPSTAT clock edge select' 'Pull CS low to enable the data read on the PGA2310 'Write data to the SSPBUF to execute SPI bus transfer-Right channel, 8bits 'Write data to the SSPBUF to execute SPI bus transfer-Left channel, 8bits 'Pull CS high to stop communication 'used only for testing to slow the volume change However, it is not crucial to read the SSPBUF register every transmission, as it will be overwritten by the next POKE command. Above is a sample program to illustrate using the SPI bus on the PIC18X. The PICAXE is configured into SPI mode and then increases the volume in steps of 0.5dB, from an attenuation of -95.5dB up to a gain of +31.5dB and then back down again. Martin Daines, Bella Vista, NSW. June 2007  39 Circuit Notebook – Continued LED stroboscope uses a frequency counter to measure RPM This stroboscope can be connected to a frequency counter so that the flash rate and hence rotational speed can be measured with high accuracy. The flash rate can be set from about 90 flashes per minute (fpm) to 21,000 fpm. IC1a is one section of a 4093 2-input NAND Schmitt trigger configured as an oscillator with three ranges selectable by switch S1. The 33kW resistor and 3.9nF capacitor combination limits the flash rate to about 21,000 fpm while VR2 (the Fine Adjust control) improves the ability to “freeze” the observed rotation. IC1a’s output is fed to a 3.5mm jack socket via a 1kW resistor to drive an external frequency counter. This enables the oscillator frequency to be read in Hertz by a frequency counter, to be interpreted as flashes per minute or RPM when the stroboscope “freezes” the rotation. IC1a also feeds a divide-by-60 counter comprising IC2 and IC3, two 4018 presettable counters. The output at pin 6 of IC3 is fed directly to pin 5 of IC1b and pin 8 of IC1c and delayed via a 10kW resistor and 4.7nF capacitor to pin 6 of IC1b. These two gates are configured as a monostable to generate brief pulses. These pulses are inverted by IC1d which drives transistor Q1 and a high brightness white LED. The RC network was chosen to produce a pulse length of about 42ms, a compromise between obtaining sufficiently bright pulses from the LED while minimising “smearing” of the observed frozen rotation. The instrument is powered by four AA cells in series providing a nominal 6V supply. At the maximum flash rate, the current drawn is about 3mA, so the cells should have a long life. The unit was built into a standard double-D cell torch case. The LED was mounted at the focus of the torch reflector while the two potentiometers were mounted in an aluminium housing shaped to fit the contour of the torch where the power switch had been. A 3-pole 4-position rotary switch was mounted in the end of the torch case for power and range selection. The circuit was mounted on a small piece of matrix board. A small aluminium block with a ¼-inch UNC-threaded hole in its centre was attached to the torch case, so that it can be mounted on an ordinary camera tripod. The finished stroboscope needs to be used in subdued lighting as it has far less light output than a commercial flash-tube instrument. Finally, note that it needs to be used with care as a rotating part which is apparently frozen can cause serious injuries! Peter N Churchill, Kambah, ACT. ($40) 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 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 40  Silicon Chip Thyristor & Triac Analyser, with the compliments of Peak Electronic Design Ltd – see www.peakelec.co.uk You can either email your idea to silchip<at>siliconchip.com.au or post it to PO Box 139, Collaroy, NSW 2097. siliconchip.com.au Egg timer uses one CMOS IC This simple egg timer circuit is based on a 4060B CMOS 14-stage counter/oscillator (IC1) which has an inbuilt oscillator. The external RC components at pins 9, 10 & 11 of IC1 determine the oscillator’s frequency and hence the total cooking time. This period can be varied using potentiometer VR1. IC1’s O3, O6 & O13 outputs gate transistor Q1 which in turn controls a small piezoelectric buzzer. This buzzer makes a telephone-like beep-beep sound when the egg is cooked. LED1 provides a flashing indicator during the time-out period. It’s driven by IC1’s O4 output. Any general purpose NPN transistor can be used for Q1 while the diodes can be any small signal type such as 1N914 or 1N4148. The buzzer must have its own internal oscillator. Its beep-beep action re- Power Supplies sults from the sequence of pulses provided by the diode gating. The timer circuit starts when power is applied via switch S1. To restart the timer, it must be switched Oscilloscopes RF Generators off and then on again. Power for the circuit can be provided by a 9V battery. Geoff Nicholls, Glinde, Germany. ($30) Frequency Counters Spectrum Analysers HAMEG Instruments have always been recognised for the consistent quality and nocompromise value of German engineering. And now the news is even better! With more new products, an attractive educational discount scheme and lower prices for 2007 you owe it to yourself to find out more. Call us please on 1-300-853-407 Test Equipment: Sales, Service and Calibration siliconchip.com.au 1-300-853-407 www.triosmartcal.com.au June 2007  41 K NOCK AK KNOCK DETECTOR For The Programmable Ignition System Use it to help program engine timing and/or to automatically retard the ignition timing in response to knock level The Programmable Ignition System would not be complete without the addition of engine knock sensing. This Knock Detector is useful for adjusting ignition timing maps and can also automatically retard the ignition timing if engine knock is detected. E NGINE KNOCK IS often a problem in cars and can cause serious engine damage if allowed to continue. In severe cases, knocking can burn holes in pistons and cause premature engine failure. And even when knocking is only light, it can reduce engine power. So how does knocking occur and what can be done about it? In a typical internal combustion engine, one or more pistons travel up and down inside cylinders to turn a crankshaft. As a piston rises inside its cylinder during the compression stroke, a mixture of fuel and air is compressed. In petrol and gas engines, 42  Silicon Chip this fuel-air mixture is then ignited to drive the piston as it starts its downward stroke. However, if the mixture is ignited too early, it will “push” against the piston as it rises towards top dead centre (TDC). If this ignition is early by only a small amount, then the engine will exhibit a knocking sound as the piston rattles within the cylinder. This effect is called “detonation”, “pinging” or “knocking”. Knocking is typically caused by the timing being too far advanced. It can also be caused by higher than normal operating temperatures or by using a lower octane fuel than normal. As a result, all modern cars with engine management systems are fitted with one or more piezoelectric knock sensors. These monitor for engine knock over specific frequency ranges and automatically retard the ignition timing if knocking begins to occur. This allows the ignition timing maps to be set close to the advance limits to ensure best performance. In addition, the use of knock sensors ensures maximum engine performance with fuels of different octane ratings, without damaging the engine. On vehicles that don’t have knock sensors, the ignition timing advance has to be set conservatively to prevent knocking. And if it does occur during driving, the only remedies are to ease off on the accelerator pedal or change down a gear. Knock detector If you are building the Programmable Ignition System (described in the March, April & May 2007 issues), then you will almost certainly want to add the Knock Detector described here. As siliconchip.com.au BY JOHN CLARKE in the designs used in modern cars, it detects and automatically corrects engine knock by retarding the timing advance at certain map sites. In addition, any detected engine knock can be displayed on the LCD Hand Controller. This makes the Knock Detector a handy tool when it comes to adjusting the programmed ignition maps in the Ignition Timing Module. As shown in the photos, all the parts for the unit are mounted on a small PC board and this is housed in the same case as the Ignition Timing Module. It takes its signal input from a commercial automotive knock sensor, while it’s signal output leads connect to the main board via a 2-way pin header. Power for the circuit is derived directly from the main board. The sensor unit itself is mounted on the engine block, to monitor the sounds from the engine. It comprises a piezo electric element that produces a signal when it detects vibration. This is mounted in a robust housing that’s suitable for the automotive environment. Basic scheme Fig.1 shows the general arrangement of the Knock Detector. In operation, the Main Features • • • • • • • • Simple add-on PC board Fits inside the Programmable Ignition System box Uses an automotive knock sensor Knock is indicated via the LCD Hand Controller display Five knock intensity levels displayed Single trimpot for sensitivity adjustment Optional automatic ignition retard Two RPM limits for knock detection output signal from the knock sensor is first fed to the Knock Detector circuit for processing. This processed signal is then fed to the Programmable Ignition Timing Module and displayed on the LCD Hand Controller. Signal processing is necessary because the knock sensor also detects all the other noises that the engine makes. This means that the wanted knock signal is buried amongst the sounds Fig.1: this diagram shows the general arrangement of the Knock Detector. The output signal from the knock sensor on the engine block is first fed to the Knock Detector circuit for processing. It’s then fed to the Programmable Ignition Timing Module and displayed on the LCD Hand Controller. Fig.2: the block diagram of the Knock Detector circuit. The incoming knock signals are first amplified and then bandpass filtered to remove unwanted engine noise signals. This processed signal is then rectified and filtered to provide a DC signal which is then fed to the Programmable Ignition Timing Module. siliconchip.com.au June 2007  43 Specifications Knock Input Range: 0-5V (0–1.25V no retard, 1.25-5V progressive retard – see Table 3). Knock Monitoring: monitored for the first 6ms after firing. This period is reduced at higher RPM to the start of dwell period. Knock Monitoring Limit: alternative 4000 RPM or 6000 RPM sensing limit. Ignition Retard Activation Period: a minimum of 10 sparks at the onset of knocking. Ignition Retard Hold Period: retard value reduced by 0.5° or 1° (depending on resolution setting) every 10 sparks until zero unless knocking re-occurs. produced by piston movement, valves and tappets opening and closing, and by various other operating parts both inside and outside the engine. This in turn means that some way of removing these unwanted signals is necessary. Fortunately, there are some strategies that can be used to separate out the knock signal from the rest of the noises. Block diagram Fig.2 shows the block diagram of the Knock Detector. As shown, the knock sensor output is first fed to an amplifier stage based on IC1c. Trimpot (VR1) is used to set the gain of this amplifier stage, to set the correct sensitivity for engine knock. According to the car manufacturers, engine knock signals generally only cover a narrow frequency range from about 4.8-6.4kHz. This means that we can more readily detect engine knock if we remove signals outside this range. That’s the purpose of the following high-pass and low-pass filter stages based on IC1b & IC1a. These only allow the frequencies of interest – ie, between 4.8kHz and 6.4kHz – to pass through. The resulting signal is then rectified by D2 and filtered to provide a DC signal voltage. This is then amplified by IC1d and fed to the Programmable Ignition Timing Module. However, that’s not the end of the signal processing, as further processing now takes place in the Ignition Timing Module itself. Engine knock only occurs when a piston is around top dead centre so if the signal is only monitored around this time, we can readily remove further unwanted noise. In practice, engine knock is monitored by the Programmable Ignition System for the first 6ms after ignition. However, at high RPM values, there is less than 6ms between successive plug firings and so the knock signal is monitored between each firing and the start of the dwell period. Another problem at high engine RPM, is that the knock signal is often swamped out by engine noise. This can lead to incorrect knock sensing. To prevent this happening, engine knock is only detected at the lower RPM ranges. This unit gives you the choice of monitoring engine knock up to 4000 RPM or up to 6000 RPM. Knock indication When engine knock is detected, the level is displayed on the LCD Hand Controller using an exclamation (!) mark. This is shown on the second line of the timing display, between the RPM site and the LOAD site values. The relative levels of knock are shown as variations on the width of this exclamation mark. For very low knock levels, a narrow single pixel wide exclamation mark is used. Successively higher levels of knock are then indicated by progressively wider exclamation marks. They range from “level 1” indication at one pixel wide through to “level 5” indication at five pixels wide. You can use this knock signal indication to determine the ignition timing sites where knocking occurs. The timing can then be retarded at those sites to minimise knocking. Note that knocking may be more severe when the engine is hot. Automatic retard An option within the Ignition Timing Module can be set to automatically retard the timing when knocking is Parts List 1 PC board, code 05106071, 96 x 55mm 1 engine knock sensor (available from an automotive wreckers) 2 2-way PC mount screw terminals 1 5mm ferrite bead (L1) (Jaycar LF-1250 or similar) 4 M3 x 12mm screws 4 6mm M3 tapped spacers 4 M3 nuts 4 3mm star washers 1 2-pin DIL socket (2.5mm spacing) 1 40mm length of 0.7mm tinned copper wire 1 2m length of automotive wire 44  Silicon Chip 1 100mm length of green medium duty hookup wire 1 200mm length of red medium duty hookup wire 1 47kW horizontal mount trimpot (code 473) (VR1) Semiconductors 1 LM324 quad op amp (IC1) 1 1N4004 (D1) 1 1N5819 Schottky diode (D2) 1 8.2V 1W zener diode (ZD1) Capacitors 1 470mF 16V electrolytic 2 100mF 16V electrolytic 1 1mF16V electrolytic 1 220nF MKT polyester 1 56nF MKT polyester 1 12nF MKT polyester 1 10nF MKT polyester 3 6.8nF MKT polyester 1 3.3nF MKT polyester 1 1nF MKT polyester 1 330pF ceramic Resistors (0.25W, 1%) 1 1MW 1 3.9kW 1 100kW 1 2.7kW 1 22kW 3 2.2kW 4 10kW 1 1kW 2 5.6kW 1 150W 1W siliconchip.com.au Circuit details Refer now to Fig.3 for the complete circuit details. The circuit designations all correspond to the designations on the block diagram (Fig.2), so the circuit should be easy to follow. Basically, a single LM324N quad op amp is used to perform all the amplification and filtering of the knock sensor signal. As shown, the signal from the knock sensor is loaded using a 10kW resistor reduce the tendency to pick up electrical noise. From there, the signal is AC-coupled to pin 10 of IC1c via a 1nF capacitor and inductor L1. The latter is included to reduce radio frequency (RF) signal pick-up. IC1c functions as a non-inverting amplifier stage, with gain set by trimpot VR1. It’s pin 10 input is biased to half-supply via a 1MW resistor and two 10kW resistors across the 8.2V siliconchip.com.au Fig.3: the circuit is based on a single LM324 quad op amp. IC1c amplifies the incoming knock signal, while IC1b & IC1a are the high-pass and low-pass filter stages. Diode D2 rectifies the bandpass filtered signal and feeds op amp IC1d which then drives the Programmable Ignition Timing Module. detected. The amount depends on the severity of the knock signal – the higher the knock signal, the greater the retard. If the timing map has been set up with 0.5° resolution, the retard ranges from 0.5° at light knock levels through to 6.0° at severe levels. Similarly, for the 1° resolution, the retard ranges from 1-12°. When knocking is detected, the ignition is retarded for a period of 10 sparks. The retard value is then decreased by either 0.5° or 1° (depending on the resolution) every 10 sparks until it reaches zero or until there is further detection of knock. This slow release of ignition retardation helps to prevent the knock level increasing to any more than a very light level. It does this because as retardation is reduced, a small amount of knock may again be detected and so the timing will again be retarded to eliminate this. If there is no knock signal, then the ignition timing reverts to normal until knock is again detected. Note that we do not advocate advancing the ignition timing map to the point where there is constant knocking and then relying on the knock retard feature to correct for this. Instead, the Knock Detector is just there as an insurance against excessive knock in unusual circumstances – eg, when the fuel octane rating is lower than normal or if the engine is abnormally hot or there is some other unusual operating condition. June 2007  45 Table 2: Capacitor Codes Value 220nF 56nF 12nF 10nF 6.8nF 3.3nF 1nF 330pF EIA Code   224   563   123   103   682   332   102   331 IEC Code 220n   56n   12n   10n   6n8   3n3   1n0 330p gain at high frequencies to prevent oscillation. IC1c’s output appears at pin 8 and is fed to pin 6 of IC1b via an RC filter network. IC1b functions as a 4.8kHz high-pass filter, as set by the 6.8nF capacitors and the 10kW & 2.2kW resistors in the input and feedback networks. Signals above 4.8kHz can pass through to the pin 7 output, while signals below this frequency are attenuated. In operation, any signals below 4.8kHz are attenuated by 40dB (100 times) per decade. So at 480Hz, the output level at pin 7 is some 100 times less than for signals above 4.8kHz, assuming the same level of signal is applied to the input to the filter. IC1b in turn feeds IC1a which is configured as a low-pass filter. This filter attenuates signals above 6.4kHz, as set by its associated 12nF & 3.3nF capacitors and the 5.6kW & 2.7kW resistors. As with IC1c, both IC1b and IC1a are biased at half-supply voltage (ie, Vcc/2) and so the output signal from pin 1 of IC1a swings above and below this point. Fig.4: follow this parts layout diagram to assemble the PC board. It should only take you half an hour or so to build but watch the orientation of all polarised parts (ie, the IC, diodes, zener diode & electrolytic capacitors). This view shows the fully-assembled module. It’s a good idea to secure the electrolytic capacitors using hot-melt glue around their bases, to prevent them from vibrating and breaking their leads . supply rail – ie, it is biased to 4.1V. This allows IC1c’s output to swing symmetrically above and below this 4.1V bias voltage. Depending on the setting of VR1, mF Code 0.22mF .056mF .012mF .01mF .0068mF .0033mF .001mF   NA IC1c can provide a gain of up to 48 times. The 1kW resistor and 56nF capacitor on pin 9 roll off the gain below 2.8kHz, while the 330pF capacitor across the 47kW trimpot rolls off the Rectifier stage Following IC1a, the signal is Table 1: Resistor Colour Codes o o o o o o o o o o o No. 1 1 1 4 2 1 1 3 2 1 46  Silicon Chip Value 1MW 100kW 22kW 10kW 5.6kW 3.9kW 2.7kW 2.2kW 1kW 150W 4-Band Code (1%) brown black green brown brown black yellow brown red red orange brown brown black orange brown green blue red brown orange white red brown red violet red brown red red red brown brown black red brown brown green brown brown 5-Band Code (1%) brown black black yellow brown brown black black orange brown red red black red brown brown black black red brown green blue black brown brown orange white black brown brown red violet black brown brown red red black brown brown brown black black brown brown brown green black black brown siliconchip.com.au JOIN THE TECHNOLOGY AGE NOW with PICAXE Developed as a teaching tool, the PICAXE is a low-cost “brain” for almost any project The knock sensor can be mounted directly on the engine head or attached to it via a bracket as shown here. Knock sensors are readily available secondhand from wrecking yards. AC-coupled via a 1mF capacitor to diode D2. This diode rectifies the signal, allowing only positive excursions of the waveform to pass through. The rectified signal is then filtered using a 22kW resistor and a 10nF capacitor. The 100kW resistor discharges the capacitor in the absence of signal. In practice, the 100kW resistor gives a discharge time of around 1ms. This time constant is long enough to smooth out the 4.8-6.4kHz signals but still short enough to quickly discharge the capacitor in the absence of a knock signal between cylinder firings. Finally, the rectified and filtered signal is fed to non-inverting amplifier stage IC1d. This operates with a gain of 4.9, as set by the 3.9kW and 1kW feedback resistors. In practice, it amplifies the DC signal at pin 12 from a typical maximum of 1.2V to 5.88V. Its output appears at pin 14 and is fed to the Ignition Timing Module via a 2.2kW current-limiting resistor. Power supply Power for the circuit is derived from the vehicle’s 12V ignition supply via reverse-polarity protection diode D1. In practice, this supply is picked up from the Ignition Timing Module’s PC board. Following D1, the power is fed via a 150W resistor to zener diode ZD1 siliconchip.com.au which regulates the supply rail to 8.2V. This rail is then filtered using a 470mF electrolytic capacitor and is used to power IC1. In addition, a half-supply rail is derived using two 10kW divider resistors. This is decoupled using a 100mF electrolytic capacitor and is used to bias IC1c, IC1b & IC1a, as indicated previously. A second 100mF electrolytic capacitor provides additional supply rail decoupling for IC1. Construction All the parts for the Knock Detector mount on a PC board coded 05106071 and measuring 96 x 55mm. Before assembly, check the PC board for correct hole sizes and that all the tracks are intact and that there are no shorts between tracks. Repair these if necessary. Fig.4 shows the assembly details. Begin by installing the resistors, using Table 1 as a guide to selecting the values. As usual, it’s also a good idea to check them using a digital multimeter, just to make sure. Next, install diodes D1 & D2, followed by zener diode ZD1. Be sure to install the correct part in each location and make sure they are all oriented correctly. IC1 can then be installed, again making sure it is oriented correctly. The capacitors can now all go in, starting with the smaller MKT and Easy to use and understand, professionals & hobbyists can be productive within minutes. Free software development system and low-cost in-circuit programming. Variety of hardware, project boards and kits to suit your application. Digital, analog, serial RS232, 1-Wire™, and I2C facilities. PC connectivity. Applications include: Datalogging Robotics Measurement & instruments Motor & lighting control Farming & agriculture Internet server Wireless links Colour sensing Fun games Distributed in Australia by Microzed Computers Pty Limited Phone 1300 735 420 Fax 1300 735 421 www.microzed.com.au June 2007  47 Fig.5: the Knock Detector PC board mounts on the case lid of the Programmable Ignition Timing Module and is wired to the main board and to the knock sensor as shown here. ceramic types (see Table 2 for the capacitor codes). Follow these with the electrolytics, taking care to orientate each one as shown on Fig.4. Finally, install VR1, the 4-way screw terminal block and inductor L1. The inductor simply consists of a tinned copper wire link fitted with a 5mmlong ferrite bead. Mounting details The Knock Detector PC board is mounted on the inside of the case lid used for the Ignition Timing Module. As shown in the photo, it must be positioned towards one side, so that it does not foul the Sensym manifold pressure sensor on the main PC board (if fitted). The first step is to mark out and drill four 3mm mounting holes in the box lid. That done, mount the PC board on 6mm-long stand-offs and secure it using M3 x 12mm screws, M3 nuts and star lockwashers. After that, it’s just a matter of run- ning the external wiring connections as shown in Fig.5. These include the +12V, GND and Output leads to the main board. The Input signal lead is run to the knock sensor via the cable gland in the side of the box. Mounting the knock sensor The knock sensor should mounted directly on the engine head if possible. If this is not easy to do, the next best option is to use a mounting bracket. This bracket must be solid enough so that it does not vibrate and cause false knock signals. In our case, we mounted the knock sensor via a bracket because the screw thread on the sensor was too large to directly bolt into the engine head. This worked quite satisfactorily and was sufficient to detect knock. Setting it up The setting-up procedure is quite straightforward. Just follow these steps: Table 3: Timing Retard vs Knock Intensity Displayed Knock Intensity Retard Range For 0.5-Degree Resolution Retard Range For 1-Degree Resolution 1 0.5-1.0 degree 1-2 degrees 2 1.5-2.0 degrees 3-4 degrees 3 2.5-3.0 degrees 5-6 degrees 4 3.5-4.5 degrees 7-9 degrees 5 5.0-6.0 degrees 10-12 degrees 48  Silicon Chip (1) In the settings mode for the Programmable Ignition, set the “Knock” option to OFF (this simply turns off automatic retard) and set the RPM limit to 4000 RPM. Alternatively, if your car’s engine spins out further than 6000 RPM, use the 6000 RPM maximum. Note, however, that you may need to revert to the lower limit if the engine is noisy enough to cause false knock detection above 4000 RPM. (2) Set VR1 fully clockwise. (3) Rev the engine up and down its range and slowly adjust VR1 anticlockwise until no knock is indicated during this procedure. This is done because the engine is unlikely to knock when just free revving and so we can set the sensitivity just low enough to prevent false knock indication due to normal engine noises. However, this setting should still be sufficiently sensitive to detect true engine knock if it occurs. Typically, engine knock can occur when an engine is in its mid-rev range and under load. Find any trouble spots that cause knocking and note the timing values for these RPM and Load sites. The timing at these sites can then be reduced until the knock level is minimised or removed. If you wish, the “Knock” option can now be set to ON using the LCD Hand Controller. This will enable the automatic knock retard feature in the Programmable Ignition. Table 3 shows the amount of retard for each of the displayed knock intensity levels. SC siliconchip.com.au 7” Electronic Digital Photo Frames Show off your digital images or movies. Insert your memory card and select the desired display style. You can also play a background sound track or show video clips. They can be desk or wall mounted and come complete with remote control, power supply and A/V cables. The units also have an A/V input so you can play analogue signals as well. • Supports SM, SD, XD, MS & MMC card formats • Supports MPEG1, MPEG2, MPEG4, JPEG, MP3 Two types available: White Acrylic Cat. QM-3765 • 220(L) x 156(H) x 40(D)mm Both (each) Brushed Silver Finish Cat. QM-3759 $199.00 • 238(L) x184(H) x 40(D)mm SAVE Was $249.00 Limited Stock $50 VoIP USB Wireless Phone Make or answer Internet calls just like using a regular phone. 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CT-2023 datasheet and buy as securely packed. $49.95ea a Or set of 4 for • Size: 89 x 74mm $179.60! • Type: Regular-phase 100mm That's' only $44.90 each! ribbon tweeters • Power: 20 watts RMS, 50W max. • SPL: 92dB/ watt • Freq Resp: 6K-40KHz +/-2dB • Impedance: 8 ohms • Crossover Freq: 6,400Hz (12dB/Octave) FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 New Kit 4 Channel Guitar Amplifier Kit Refer: Silicon Chip May 2007 This is an improved version of our popular guitar mixer kit and has a number of enhancements that make it even more versatile. The input sensitivity of each of the four channels is adjustable from a few millivolts to over 1 volt, so you plug in a range of input signals from a microphone to a line level signal from a CD player etc. A headphone amplifier circuit is also included for monitoring purposes. A three stage EQ is also included, making this a very versatile mixer that will operate from 12 volts. Kit includes PCB with overlay and all electronic components. 3.6V Cordless Driver Drill with Charging Cradle This driver has forward and reverse with a 1/4" hex bit holder instead of a conventional chuck for quick bit changes. It also has a quality 3.6V lithium-ion battery, a desktop charger, charge status LEDs and includes 5 bits: 5mm flat, #2 Phillips, 2, 2.5 & 3mm twist drills plus a generalCat. TD-2494 purpose 1/4" hex bit holder. • Speed: 150 RPM $49.95 • Size: 140 x 140mm Cat. KC-5448 $99.00 50W 6.5" Powered Subwoofer Add this subwoofer to our turntable GE-4063 $199 for a real juke box sound! The subwoofer includes a 50WRMS amplifier housed in a solid black wooden enclosure. Perfect for use in flats or home units. • Size: 250(W) x Cat. CS-2458 350(H) x 420(D)mm $99.95 Solar Power System with Lights The kit includes a 10W solar panel, 9Ah SLA battery and 2 x 12V 5W energy saving fluorescent lights. The battery is housed in Get a basic a sturdy metal enclosure with DC solar setup off sockets for all the connections, and the ground 4 outlets to power your lights and other devices. The battery can also be recharged from the mains with an Cat. MP-4550 optional SLA charger. See website or $199.00 our catalogue for details. New Store in Cairns Qld Now Open! 194 Mulgrave Rd Queensland Ph: (07) 4041 6747 This super-store has ample all day parking and is over 230m2! Better. More Technical INTERNET> www.jaycar.com.au Temperature & Humidity Datalogger This USB datalogger logs up to 3200 readings (1600 temperature, 1600 humidity) in intervals of 2 seconds to 2 hours per reading. It records at the prescribed intervals and will flash an alarm LED if the user-defined minimum or maximum temperature is exceeded. A mounting bracket is included with screw or self-adhesive attachment. Cat. QP-6013 • Range: -40-70°C (-40-158°F), 0-100% $99.95 relative humidity, • Accuracy: ±1°C (1.8°F), ±3% relative humidity • Resolution: 0.1°, 0.1% RH Deluxe LCD Screen Cleaning Kit The unique triangular design means you can get into the corners for a complete clean. The soft micro fibre pad removes dust, lint, oil and finger marks Cat. AR-1419 from LCD, plasma and CRT screens. 60ml fluid & antistatic brush included. $24.95 SLA Deep-Cycle Gel Batteries They can be operated and charged in any position, are leak-proof and completely sealed. Ideal for solar power, camping, 4WD and auxilliary applications. Two types available: SB-1696 2V 200Ah • Weighs: 14.5kg • Size: 170(W) x 110(D) x SB-1698 362(H)mm (with SB-1696 terminal cover) Cat. SB-1698 Not stocked in all SB-1698 stores. Call first 12V 26Ah or order online. • Weighs: 8.5kg • Size: 165(W) x 172(D) x 110(H)mm $99.95 Cat. SB-1696 $269.00 1 The last bastion of male dominance has been breached - the barbeque! The set contains: spatula, scraper, wire brush, tongs, knife and skewers, all housed in a pink storage case. • Case measures: 450(L) x 400(W) x 150(D)mm Cat. GG-2307 $29.95 Breakdown & Emergency Road Flasher Simply place them on the ground to warn other motorists and guide them around a problem. The lights have three bright LEDs that can be easily seen from a distance. They are made from tough Cat. ST-3185 plastic and have two lighting options, steady and flashing. • Batteries not incl. $9.95 • Size: 90(dia) x 25(H)mm Pivot Head LED Lantern It has 20 super-bright white LEDs and a two mode lighting switch for lowlevel and ultra-bright illumination. The head pivots an approximate 180° so you can focus on a specific item or have it shining on the ceiling of a room or even a tent. Cat. ST-3053 • Requires 3 x D batteries $24.95 not included Automotive Car Kettle Simply plug into your car's cigarette lighter socket. Holds up to 550ml and makes up to 4 cups of tea, coffee, soup or any other hot beverage. • 235(H) x 95(dia)mm Cat. GH-1380 $15.95 In-Car Coffee Maker Simply connect to a 12VDC power source and have freshly brewed coffee in under 20 minutes even in the most remote location. Great for the intrepid traveller. It holds up to 500ml, has a reusable filter and has a 12V 5m power lead terminated to Cat. GH-1381 alligator clips. $29.95 • Draws 24A/300W max Listen to your iPod® or MP3 player without missing a call from your mobile phone. This tiny device will allow you to answer, hang up Cat. XC-4894 and swap between your music source and mobile handset as $99.95 well as adjusting the volume. Weather Station with Wireless Sensors and Doorbell The system consists of two wireless outdoor sensors, a wireless doorbell and an indoor receiver. The device will measure indoor and two outdoor temperatures, humidity, barometric change as well as the respective min/max temperatures. • Indoor display size: 225(W) x 260(H) x 27(D)mm full See ourf 12V range o -store in Gadgets Has a built-in, thermostatically controlled heater and will maintain one of four selectable preset temperature settings ranging from room temp to very hot. Heats from 10 to 70°C • Includes 1.5m detachable 12V power lead with Cat. GH-1301 cigarette lighter plug $29.95 Cat. XC-0336 $99.95 The 350mm platform accommodates a 150mm2 1.3W solar panel that charges a Ni-Cd battery pack. It features 2 white LEDs for effect at night and comes complete with a remote control to operate from a distance of 15m. The lily shaped fountain is supplied with 2 spare sprinklers, remote Cat. YH-5452 control & batteries. $69.95 • Runs for 45mins on a full charge. Communication 38 Channel UHF Pocket CB Radio It has a 4 step scrambling function to allow for private communication on what is normally a 'public' broadcast up to 5km (clear line of sight). Each transceiver is supplied with a rechargeable 650mAH pack however 3 x AAA batteries can be used in emergencies. It features a twin charging base so Cat. DC-1025 purchase an extra handset DC-1028 $59.95 for only $49.95 Designed to fit into a full-face helmet with the included self-adhesive Velcro mounts, it can be easily removed when not in use. Add a second set and use it as a bike to bike or rider to pillion intercom. Handlebar-mounted push-to-talk button included.Compatible with the following UHF CBs: DC-1025, DC-1028, DC-1040, DC-1045 & DC-1060. Cat. DC-1037 • Headset cable length: 1.6m $99.00 • PTT button cable length: 1.3m 3 Watt 38 Channel UHF CB Radio with Scrambler Up to 10km transmission range. Maximum output is 3 watts with 1W battery saver mode. All 38 legal channels are utilised as well as CTCSS sub channel calling, automatic muting, and scrambling. Supplied with a high gain (168mm) antenna. SMA connector allows Cat. DC-1060 the use of external $169.00 antennas. Better. More Technical This unit gives full VHF channel coverage of all international VHF marine channels in a compact tough hand-held unit complete with LCD. • 56 channels with alphanumeric display • Charging cradle with 12VDC plugpack • Full specifications on website Complies with Australian Standards for VHF Transceivers (AS/NZ4415.1) Cat. DC-1094 $199.95 Rear View Mirror TFT Monitor with Camera Remote Controlled Solar Fountain Motorcycle Headset for UHF CB Radios Stainless Steel Travel Mug with Built-in Heater 2 5W Marine VHF Transceiver USB Bluetooth Hands-Free Stereo Earphones Pink BBQ Tool Set A complete rear-view safety package including a TFT monitor and a flush mount simple to install colour camera. Includes 5 metre video/power cable. • 7" screen • Simply clips over your sun visor or rear vision mirror Cat. QM-3762 $299.00 Automotive Interior LED Up-grade Kit Its luminance is 2 to 3 times stronger & the LED lamp uses one-eighth to one-tenth power of traditional light bulbs and can continuously light up for over 10,000 hours. Cat. ZD-0485 $29.95 Lighting Solutions Solar Powered LED Garden Spotlight If you're outside when darkness falls, the spotlight switches on automatically. It uses high-powered LEDs and a built-in solar panel to charge See o the internal batteries during the range o ur full f day and allows the system to Lights inGarden -store operate during the night, Cat. SL-2714 • 11 LEDs - Illumination duration: 10 hours $49.95 • Lamp 80mm(Dia.) Stainless Steel Flexible BBQ Lamp This outdoor light is made from rust-resistant stainless steel and is battery powered. It is fitted with 25mm clamping jaws and 480mm gooseneck so that it can be attached to whatever is handy, be it table, fence or BBQ. Cat. SL-2806 • Runs on 4 x AA batteries, $29.95 available separately. 63 LED Work Light with Tripod Stand The ultimate battery powered portable work light available. It features an adjustable head that can be pointed up or down to direct the light where you want it. Every home and car should have one of these beauties. Cat. ST-3126 • Mains and car chargers included • Size 100(W) x 300(H) x 120(D)mm $49.95 FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 INTERNET> www.jaycar.com.au Mini 4 Port HUB USB 2.0 Digital Map Distance Calculator This unit will allow up to 4 USB peripherals to be utilised without the loss of speed. It is plug and play with auto-detection and safe removal from your USB port. • USB interface lead included Cat. XC-4864 $19.95 All-In-One Memory Card Reader Exchange data between your PC and all the flash memory cards currently on the market. One simple solution, no need for different card readers for different electronic devices. XPERT DVD Maker $19.95 Convert all your old VHS tapes and camcorder cassettes to DVD! XPERT DVD Maker converts on the fly, so there is no need for excessive amounts of free disk space. All you need is a DVD burner and you can store your memories forever! Was $99.95 SAVE $20 Cat. XC-4811 $79.95 Cat. XC-4890 $29.95 Gadgets for the Home Digital Thermometer for Fridge or Freezer The unit has a 1m 'out' or fridge sensor and will trigger an alarm when the fridge, freezer or incubator rises or falls below set temperatures. It has an 'in' temperature range of -10 to +50°C and an 'out' range of -50 to +70°C. Includes magnet for Cat. QM-7209 mounting and AAA battery. $16.95 • 67(W) x 39(H) x 15(D)mm Countdown Timer Use it for projects, parking, exercising or studying. It's water resistant, has a memory setting for frequently used values and the buzzer alerts you to when your time is up. • Countdown range 99 hours 99 minutes 99 seconds Cat. XC-0271 • Batteries included $19.95 • 88(W) x 130(H) x 22(D)mm Push-on LED Light Ideal for sheds, cupboards, lofts, stairways or even by the back door this four LED push-on/off light with its self adhesive backing will stick just about anywhere. • Requires 3 x AAA batteries •Measures 60 (Dia.)mm $19.95 This trap does not blow insects apart with high-voltage electricity. It is almost noiseless, very smart and very safe. It uses an electronically controlled LED lighting and heating coil that produces intermittent light selected to coincide with spectral sensitivity peaks of many mosquito species. Approx. Cat. YS-5518 300mm tall • 240V mains $179.00 adaptor included Was $199 The 'Frequency Shifting' technology used in this repeller may be effective against most common household pests including rats, mice, cockroaches, silverfish etc. Mains plugpack included. SAVE $20 $6.95 $29.95 Defend your desk against the Axis of Evil. We have three different models so you can use the WMD of choice in your local conflict. Forget pathetic emails wars, have a proper battle. All three units have full pan tilt control USB Missile Launcher Mk II and come with 3 missiles. With full directional movement, you can now declare war on someone up to 7m The USB Launcher MK II away! It uses amovement burst of with an Full directional air ejecting the foam airburst launching system. It has a missile instead of aand requires camouflage finish spring loaded mechanism. no batteries. USB powered, thehigh launcher • Stands 120mm comes with software, 3 • Replacement soft foam missiles, target, missiles pkt 3 Cat. GE-4074 Fires up to sound effects and USB lead. GE-4075 $3.95 7 metres $59.95 • Base measures 110mm(Dia.) • Stands 120mm high The Original USB Launcher Spring loaded launching system with 3 missiles included. USB operated, it has sound effects and requires 3 x AA batteries (not included). Stands 150mm high. • Replacement missiles pkt 3 GE-4073 $6.95 Desktop Missile Launcher Cat. ST-3188 Cat. YS-5520 Ready Aim Fire!!! Cat. GE-4072 $49.95 No software of computer connection required with this unit, just insert the Cat. GE-4082 batteries and fire at will. $29.95 Stands 170mm high. • Replacement missiles pkt 3 GE-4083 $6.95 FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 Cat. XC-0375 Ultrasonic Pest Repeller USB Class 2 Bluetooth Dongle Short range wireless connectivity with mobile phones, PDAs, and some keyboards and mice. • 10m range Attention sparkies and cablers! Use this gadget to measure your cable run from scale drawings! Megacatch Mosquito Trap Cat. XC-4856 Desktop Bling Measure distances on a map or chart, just by rolling this fantastic device along the planned route. Includes calculator, clock, light and compass. • Batteries included INTERNET> www.jaycar.com.au What better way to jazz up your desk than with these pink and white rhinestone desk accessories. Rhinestone Mouse Rhinestone Dual Power Calculator Rhinestone Stapler Cat. GH-1890 $19.95 Cat. GH-1892 Cat. GH-1894 $17.95 $14.95 Sonic Grenade After a 20 second delay, your Sonic Grenade will sound its annoying alarm continuously until you replace the pin. It makes a great personal alarm and has 3 pitch levels. Great for waking up the kids! • Requires 3 x AAA Cat. GT-3112 batteries not incl. $19.95 • 125 mm high Economy Headtorches They feature fully adjustable headstraps, are light and compact and very efficient on batteries (Requires: 3 x AAA not included). They also will never require replacement globes. ST3286: 12 White LEDs 4 settings: 4 LEDs, 8 LEDs, 12 LEDs & strobe. ST-3287: 17 White LEDs 3 settings: 4 LEDS, 17 LEDs & strobe Cat. ST-3286 $9.95 Cat. ST-3287 $14.95 Stay on Time Chasing Blue LED Analogue & Digital Clock SAVE Be mesmerised by this $25 amazing clock! The mechanism drives a 7 segment, 12 hour time display. The 200mm diameter display contains 60, 5mm high intensity blue LEDs on a 60 second illuminated circuit. Cat. AR-1788 • 9V adaptor included $74.95 • 250(L) x 250(H) x 50(W)mm Was $99.95 Multi-Function Clock with Dual Projection 7:13 Projects the time and the temperature on your wall or ceiling. The LCD constantly displays time, temperature, day and date while the alarm and snooze option finish off this neat little unit. Cat. XC-0219 • 140(L) x 34(W) x 90(H)mm • Requires 2 x AA batteries (not incl) $19.95 or 3V DC adaptor (not included) Retro Clock with Flip Digits Before LED and LCD there were these flip-digit displays. This one can be wall mounted or left on the desk or table. • Requires 2 x AA batteries • Size: 150(L) x 90(H) x 80(D)mm Better. More Technical Cat. AR-1789 $14.95 3 12V Ni-Cd/Ni-MH Charger This charger plugs directly into a car cigarette lighter outlet, making it ideal for recharging when there is no mains power or a generator available. It features automatic battery voltage detection, manual charge current adjustment, LED charge indicator, short-circuit and overload protection. The unit includes 1m cigarette lighter lead, extension lead with alligator clips, 1.8m battery charging lead with 2 pin adaptor, Cat. MB-3630 2 pin Utilux type connector for RC $59.95 battery packs and a 2 pin lead with alligator clips. Pure Sinewave Inverters Each unit is housed in a strong aluminium case and features heavy duty screw down input terminals, temperature-controlled cooling fan, standard 230VAC sockets, and an ON/OFF switch with status indicators. All our inverters are fully protected against short circuits and overloads. This fully automatic, switchmode, car battery charger utilises a four stage rapid charge design to optimise the life and performance of your car or GEL battery. Includes a top mounted carry handle and cable storage for the battery leads and clamps. • Dimensions: 270(W) x 220(H) x 120(D)mm Cat. MB-3620 $169.00 1000VA Uninterruptible Power Supply Protect your valuable computer system from power failures, preventing data loss or corruption. The included software can be set up to save your data and close down your computer automatically if the power fails. The UPS is supplied with two 12V 7Ah SLA batteries, USB interface cable and software. • 600VA UPS also available MP-5200 $129.00 Cat. ZM-9067 Applied Photovoltaics 2nd Edition 24VDC to 12VDC 8 Amp Converter Allows you to run ordinary 12 volt car radios and CB equipment etc in 24 volt vehicles such as trucks and buses etc. 12VDC to 230VAC 12VDC to 230VAC 12VDC to 230VAC 24VDC to 230VAC $199.00 $349.00 $449.00 $799.00 Traveller's Ni-Cd & Ni-MH Battery Pack Charger $64.95 This microprocessor controlled international charger is for packs of 1-10 cells. With switchmode power and 8 interchangeable plugs this charger includes an array of safety features including a Delta V switch-off and safety timer. Cat. MB-3583 • UK, USA, Australian and European $79.95 mains plugs supplied Home Theatre Powerboard This 4 outlet powerboard features an integrated cable reel which stores its 5m extension cord. Featuring surge protection and an on-board illuminated power switch it is Cat. MS-4042 portable, easy to store and can be rolled $29.95 out at a moments notice. 13.8V 40A Switchmode Laboratory Power Supply Great for HAM Radio Cat. MP-3089 $179.95 They have a 12 to 13.8V input voltage, feature a recessed voltage selector, LED power indicator and are supplied with 7 output connectors for all major laptop brands. • Compatible brands include: Apple, Compaq, Del, HP, IBM, ACER, Sharp and Toshiba • Terminates to a fused 10 amp automotive cigarette lighter socket MP-3463: 15/16/18/19/20/22/24VDC <at> 3.5 amps 80W Was $39.95 MP-3467: 15/16/18/19/20VDC<at> 6 amps 22/24VDC <at> 5 amps 120W Was $69.95 SAVE $22 Better. More Technical Comprehensive coverage of photovoltaic devices. It includes the characteristics of sunlight, the detailed operation of solar cells and specific purpose photovoltaic applications. Quite technical and detailed. Soft cover, 313 pages with illustrations. Cat. BE-1533 Automotive Laptop Power Supplies Cat. MP-3062 4 300W 600W 1,000W 1,500W 4 Outlet Powerboard with 5M Extension Cord $199.00 A high powered 13.8V switchmode power supply delivering up to 40A and suitable for use in development and test environments. The internal cooling fan will assist cooling at higher outputs and the unit has easy to use 4mm banana connectors. MI-5153 MI-5155 MI-5157 MI-5159 Surge protection and filtering are provided for the mains power to all your equipment and further protection is provided by the in-built circuit breaker. This powerboard also has telephone protection, data protection for a network connection, Cat. MS-4024 satellite/cable TV video protection, and $59.95 protection for TV aerials. Cat. MP-5202 See our full range of Solar Equipment in our If you are looking for a long 2007 Catalogue life, premium solar panel with a 10 year warranty, you can't go past this latest addition to our solar panel range. The panel has an array of 36 polycrystalline cells and will charge a 12V battery in virtually any climate. The modules are strong and designed to withstand the impact of a 25mm hail stone travelling at terminal velocity. $599.00 Price Breakthrough Rugged 16 Amp 12 Volt Car Battery Charger 65W BP Solar Panel $49.95 Solar Charger & Power Bank Charge your phone, MP3 player and other digital devices wherever you are. Charge by the sun, USB port or mains power. Depending on your method, charging will be ready in less than 12 hrs. • Li-ion rechargeable battery incl. • Output voltage/current 5.5V/500mA • Suits most phone types Motorola, Nokia, Samsung, Sony Cat. MB-3588 Ericsson, Siemens • Folded size: 120(L) x $69.95 17(W) x 62(H)mm Mains Adaptor for USB Powered Appliances Charge a USB device without the need to connect it to your computer. A switchmode adaptor with 5VDC output and 1A maximum current draw. USB cable Cat. MP-3450 sold separately. $14.95 Was $19.95 SAVE $5.00 Battery Charger with LCD (12VDC & 240VAC) 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 Cat. MB-3543 integrated LCD that is $49.95 backlit. • Supplied with mains and car chargers Four Pack Ni-MH Rechargeable Batteries SAVE $5.00 Cat. MP-3463 $34.95 Cat. MP-3467 $47.95 Modern digital devices require high current high drain performance cells. These true high capacity batteries will provide the best in portable power. AA 2500mAh SB-1738 $19.50 AA 2400mAh SB-1735 $15.95 AA 2000mAh SB-1737 $13.95 AAA 900mAh SB-1739 $11.95 FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 INTERNET> www.jaycar.com.au Child or Pet Door Annunciator Simply mount at any entrance and the alarm will sound for 30 seconds every time your child or pet passes through. It won't go off when an adult passes as the sensors discriminate between adults, toddlers or pets. • Batteries not included • Unit measures 1 metre Cat. LA-5166 when assembled Infrared Security Spotlight This great unit acts as an intercom, with a wireless receiver. Take it out the back, or around the house. It also has electronic door strike control, so you can let your visitors in! • LA-5078 Optional electronic door strike available separately $44.95 • Range: 30m Was $129.00 $49.95 A surveillance camera with an incorporated digital recorder. The 380TV line VGA camera has composite video out and can be either mains or battery powered. It has continuous or motion-detection record options and includes 64MB of flash memory. Mains power supply and all mounting hardware included. Was $349.00 Cat. QC-3652 $79.95 2.4GHz Colour Mini Wireless Camera Kit The camera transmits audio and video up to 100m (line of sight) to the receiver. It can be powered by a plugpack or by its in-built rechargeable battery, and has 4 transmission channels to minimise interference. The receiver has composite video out and is powered by the supplied plugpack, includes camera with brackets, power supplies, AV lead & Cat. QC-3569 receiver unit • Camera: 67(L) x 22(W) mm $199.00 • Receiver: 78(L) x 68(W) x 16(D)mm Alarm Packages Four Sector Wireless Alarm System The system is simple to install and the alarm panel will detect and 'learn' which sensors have been installed. The control unit also monitors the system status and sensor battery condition to ensure system reliability. Includes control panel with keypad, a passive IR motion sensor, and a reed Cat. LA-5134 switch sensor for door or window $99.95 protection. • Batteries and plugpack included Four Sector Security Alarm System All system components (sensors, sirens) are connected to the control unit via a two core flat wire. The unit has a built-in keypad with status LED and three modes of operation (Home, Out, Off). All sensors and sounders are line protected so any attempt to interfere will sound the alarm. • System includes control unit, 2 movement detector PIRs, 4 door/window contacts, external siren, 240VAC adaptor, 50m two-core flat wire, clips & screw/wall plug packs. Was $199 Cat. LA-5475 $149 SAVE $50 $99.95 SAVE $50 Cat. QV-3092 $299.00 Dome Cameras for Every Application Mini Colour CCD Cat. QC-3291 $69.00 SENSORS INSIDE The dome of this camera is made of reinforced polycarbonate and is designed to withstand a 300kg impact without cracking. The base is made of solid diecast aluminum. It features 1/4" Sharp CCD sensor & a 350 TV line resolution. • 92(dia) x 70(H)mm $129.00 Vandal Resistant Colour CCD SENSOR This 520 TV line camera is made of extremely durable materials and will survive impacts that would destroy other cameras. Features a Sony HAD CCD sensor, 3 axis movement (pan 180°, tilt 180° and rotate 170°) & operates from 12VDC. • 93(dia) x 69(H)mm INTERNET> www.jaycar.com.au Cat. LR-8839 $59.95 Colour CCD Variable Focal Length Camera $399.00 Vandal Resistant Colour CCD Unlock your car doors as you approach. This system is easy to install and comes complete with wiring loom, two remote keyfobs and is backed with a 12 month warranty. Was $69.95 Cat. AI-5510 With a built-in sensor just connect this unit to a standard camera with composite video and the unit will record audio and video to an SD card. The AV input/output sockets connect to an external monitor (not included) and the front panel of the unit has full playback functions. • 5VDC plugpack and AV cables included Cat. QV-3094 • Requires 2 x AA batteries for portable use SD card not included Small in size (only 72mm diameter) this tiny camera is excellent value for money and has specifications comparable to some of our higher priced dome cameras. It features a 1/4" Sharp CCD sensor and an 350 TV line resolution.• 72(dia) x 52(H)mm Remote Controlled Central Locking System SAVE $10 Mini Portable Security Recorder FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 SAVE $29.05 Surveillance Camera with DV Capture The long-range beam has a range of 30 metres and will switch on automatically as darkness falls or ordinary lights are turned off. HIgher power spotlight also available QC-3655 Was $249, Now $199 Save $50 Wireless Intercom with Door Release This 380TV line camera features a Sony HDD CCD sensor, flicker reduction technology, auto iris and auto white balance, back light compensation and operates on 12VDC or 24VAC. • 160(L) x 52(W) x 48(D)mm SAVE $30 Was $299 Cat. QC-3518 $269.00 IP Camera with 6 IR LEDs This compact colour IP camera can be used in a network and will provide world-wide video coverage SAVE through internet explorer. The camera $50 incorporates a built-in web-server and includes motion detection software. Cat. QC-3396 The camera has six infrared LEDs to provide night vision capabilities. $199.00 • Supplied with mounting Wireless IP bracket, software, and Camera also available mains power adaptor QC-3398 Was 349 NOW $299 Save $50 Was $249 DVR Camera Packages Quad Processor with 2 Colour CMOS Cameras and Remote Control Add a monitor and you have a complete surveillance system. With 2 colour IR cameras, this processor turns any standard TV or monitor into a mulitplexer. It can display a single camera view, or combinations of different camera views including one or two picture-in-picture, or automatic Cat. QV-3095 sequencing.Plugpacks for cameras $349.00 and processor included. DVR Camera Kit with Colour Dome and IP56 Cameras Cat. QC-3293 Cat. QC-3290 $299.00 The DVR is fitted with a 250GB hard drive, can accommodate up to 4 cameras with power derived from the DVR and will allow you to Includ 250GB Hes record and view up to 4 cameras DD simultaneously. Package includes the DVR with a dome and outdoor IR camera with bracket, mounting hardware, power supply, 14m camera connect cable, Cat. QV-3085 software, USB interface lead & user manual. $999.00 Better. More Technical 5 5.8GHz Wireless Audio Video Sender Noise Cancelling Folding Headphones These hi-tech headphones have a built-in noise cancelling circuit that reduces background noise by as much as 18dB. A fold-away design makes for easy storage and adaptors are Cat. AA-2055 included for airline use. $59.95 Batteries included. 2 x 100WRMS Stereo Amplifier with Remote Control A no-nonsense stereo amplifier that will form the heart of an impressive entertainment system. Rated at a generous 100WRMS per Cat. AA-0470 channel, this two-channel amplifier $199.00 features a microphone input and quality screwdown speaker terminals. Wireless UHF Dual Channel Microphone Receiver Kit This wireless microphone system features two separate channels, one for each mic. Output is either via separate Cat. AM-4078 balanced XLR socket, one for $199.00 each channel, or via an unbalanced line with the two channels mixed. The system includes 2 microphones & batteries, receiver unit, 14VDC Includes two Microphones plugpack and 1m 6.5mm mono plug to 6.5mm mono plug lead. Retro Inspired Dynamic Microphone It has a smooth, wide frequency response making it ideal for vocalists. Featuring a neodymium magnet, its body is made from heavy-duty polished diecast aluminium and includes a foam-lined carry case. Cat. AM-4091 • 178(L) x 70(Dia.)mm $79.95 7" Four Input In-Car TFT Colour Video Monitor An excellent choice for in-car applications from DVDs to game consoles or reversing cameras and GPS navigation systems etc. Can also be used with multiple cameras on larger vehicle and trucks. With bracket, input and power leads & IR remote control. Cat. QM-3772 $299 Three Channel Video Distribution Amplifiers for Cars This one-to-three video amplifier is ideal for automotive use and will let you share the video signal from your in-car video or DVD system with back seat passengers or other screens in the car. •Works with all in-car video screens • 12VDC powered Cat. QC-3436 • Dimensions: 63(L) x 32(W) x $29.95 30(H)mm 6 Wireless LAN, Bluetooth, cordless phones, etc, can cause overcrowding and interference for items that transmit on the 2.4GHz band. Beat the congestion with this 5.8GHz unit and ensure crystal clear reception no matter what audio video device you choose. Complete with built-in IR remote control repeater, AV leads, power supplies and instruction manual. Additional receivers now available AR-1841 $159.95 HDMI Solutions HDMI In-Line Repeater/Extender Not C tick approved Cat. AR-1840 $249.00 Web Camera This eyeball web-cam is perfect for desktop video conferencing at home or in the office. The camera uses a VGA colour CMOS sensor with auto exposure and white balance to ensure the best picture under varying light conditions. Comes with software and connects via your computer's USB port. • Up to 1024 x 768 resolution Cat. QC-3221 • 55° Field of view $39.95 2 x 150WRMS Car Amplifier With a host of features such as variable bass EQ, remote level control and high and low pass filters, this is easily one of the best two channel amplifiers on the market today. • Winner of Car Stereo Australia Cat. AA-0424 2005 amplifier of the year $249.95 • 2 x 150WRMS <at> 4 ohms • 2 x 255WRMS <at> 2 ohms • 1 x 500WRMS <at> 4 ohms Extend the range of any HDMI device, such as a monitor or TV, set-top box, DVD player, PC or gaming system, up to 60 metres (powered). It will work with DVI components with an adaptor. Plugpack included. • Supports resolutions Cat. AC-1698 up to 1080i/1080p $79.95 • Size: 62 x 22 x 20mm Remote Controlled Two Input HDMI Switcher A simple device for switching between two high definition multimedia (HDMI) sources. Supplied with an IR receiver fitted to a 2m cable Cat. AC-1692 • Size 80(L) x 55(W) $89.95 x 17(H)mm HDMI Four Channel HDTV Input Selector This four input HDMI selector routes HD video and audio signals from the selected input to the HDMI output. The switcher also supports optical and coaxial audio inputs which are switched in unison with the HDMI. Cat. AC-1694 $199.00 HDMI Wall Plate Sockets Standard Australian/NZ GPO mount with single or double HDMI sockets for AV installations. • Single - Cat. PS-0285 $14.95 • Double - Cat. PS-0286 $24.95 HDMI Leads and Accessories DJ Dual CD Player Enclosed in a rugged, rack mountable chassis it features 8 times over sampling 1 bit D/A converter, 3 different scan speeds, pitch display, seamless loop, 25 second anti-shock, auto locking CD drawers & more! • Measures 482(W) x 90(H) x 250(D)mm Cat. AA-0490 $399.00 MP3 Player with Car Cassette Adaptor Plug in your media card with your music files, load it into the cassette deck in your car stereo and control the music with the remote unit - it provides track selection, volume control and a choice of five EQ settings. You can also plug in your head-phones and use it as a stand-alone MP3 player or connect to your PC. Cat. AR-1764 • Built-in 3.7V 250mAh battery $69.95 • Supports SD, mini SD & MMC cards Better. More Technical High definition multimedia interface (HDMI) provides high quality signals for the best in reproduction quality. Male to Male connection WQ-7400 1.5m $39.95ea WQ-7402 3.0m $49.95ea WQ-7404 5.0m $64.95ea WQ-7405 10m $99.95ea HDMI to DVI Cable WQ-7406 3.0m $39.95ea HDMI Adaptors PA-3640 HDMI Socket to Socket $14.95ea PA-3642 HDMI Plug to DVI-D Socket $14.95ea PA-3644 HDMI Plug to DVI-D Plug $14.95ea New Piezo Tweeters Similar to the now obsolete CTS brand, these 8 ohm Piezo horn tweeters have built-in protection allowing them to handle 400WRMS. At high power levels, a PTC opens, allowing the tweeter to continue to play at a compressed power level. CT-1930 RSN1005 Piezo Tweeter $9.95 CT-1932 RSN1141 Piezo Tweeter $14.95 CT-1934 RSN1142 Piezo CD Horn Tweeter $19.95 FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 INTERNET> www.jaycar.com.au DMM Leads with Blade Fuse Fitting DMM leads with fittings for standard or mini blade fuse sockets. A must for auto electricians or installers. • Length 750mm. DMM Lead Banana Plug to Blade Fuse Cat. WT-5340 DMM Lead Banana Plug to Mini Blade Fuse Cat. WT-5342 Crimping Tool for Non-Insulated Lugs Both (ea) $9.95 30A Blade Fuse Holder with Failure Lamp These blade fuse holders have an integrated red LED that will light up when the fuse blows, making it easy to find the offending fuse. Rated at 30A, they are supplied with 11mm leads and are available to suit standard blade and mini-blade fuses. Standard blade fuse Cat. SZ-2042 Mini blade fuse Cat. SZ-2043 Solid box joint and crimping dies, comfortable handles and springloading make this an easy crimper to use all day. It handles noninsulated lugs from 14-18 AWG and 22-26 AWG and also includes a built-in wire Cat. TH-1834 cutter. • 185mm long $19.95 Heavy Duty Coax Crimping Tool Both (ea) $3.70 Earth Straps A highly flexible earthing connector, commonly used in switchgear, car audio and a range of industries. • Tinned copper braid with 10mm stud holes 80 Amp 250mm with 36 x 26 strands Cat. WE-3102 WE-3102 $7.95 100 Amp 250mm with 48 x 26 Cat. WE-3104 strands $12.95 WE-3104 240VAC EMI Filters These industry standard RF/EMI filters are pre-designed to reduce line-to-ground (common mode) interference. Rated for mains voltages of 125 or 240VAC, 50 or 60Hz, they are very useful when mains cords are fixed to the outside chassis and an IEC320 inlet is not suitable. Two types available: PCB Mount EMI Filter MS-4000 Chassis Mount EMI Filter MS-4001 For crimping F, N, BNC, TNC, UHF, ST, SC & SMA connectors onto coax cable for TV and communications applications. It also has adjustable crimp force and Cat. TH-1832 3 hex dies: 2.54mm, 9.12mm & $24.95 10.3mm. Hex Ratchet Crimping Tool For crimping F, N, BNC, TNC, UHF, ST, SC & SMA connectors onto coax cable. It has an adjustable crimping force and a ratchet mechanism for repeatability. • Four hex crimping dies: 1.72mm, Cat. TH-1833 5.49mm, 8.23mm and 9.14mm. $39.95 Cat. MS-4001 $6.50 Cat. MS-4000 $4.95 Magic Ratchet Driver with 6 Bits Takes 1/4" hex bits and features a shaft that extends from 60 to 165mm. It can be locked in at lengths of 80, 100, 120 and 140mm and releases at the push of a button. • Includes 2 each slotted, Phillips and Posidriv bits • Dimensions: 220mm closed, 320mm extended Cat. TD-2057 $14.95 Duratech Temperature Controlled Soldering Station It features a high quality ceramic heating element for accurate temperature control, adjustable between 200° to 480°C. The soldering pencil is lightweight so it is comfortable for long periods. It is a great station, so check our website for details. A Great EntryLevel Soldering Station Crimp with Ease Cat. TS-1560 $99.00 This hand-held unit generates sine or square waves from 20Hz to 150kHz at up to 8V peak to peak. It also has a -20dB attenuation switch, adjustable amplitude and a 1.2V sync output for oscilloscope or frequency counter. Requires Cat. QT-2302 9V battery (not included). $99.95 Autoranging DMM A excellent, accurate meter that is Cat II rated. It features diode, frequency and capacitance test, duty cycle, continuity, relative measurement and includes battery, probes and Cat. QM-1535 SAVE holster. $5.00 Was $29.95 $24.95 2-in-1 Network Cable Tester and Digital Multimeter This innovative device is ideal for network installers or technicians. It allows the user to easily check cable integrity or measure AC & DC voltage, etc. without needing to carry two separate devices. See our website or catalogue for full specifications. Cat. XC-5078 $79.95 Budget 150mm Digital Vernier Calipers Non-Contact AC Voltage Tester with Torch About the size of a marking pen, this non-contact tester detects AC voltages from 100 - 600V. It Cat. QP-2271 can be used for detecting live mains in $17.95 outlets, powerboards or insulated wiring. It also has an LED torch and a handy pocket clip. • Requires 2 x AA batteries (not incl) This carbon composite digital caliper is ideal for general use and situations where the cost of our precision stainless steel tool isn't justified. The digital display is calibrated in imperial and metric units with a corresponding vernier scale etched onto the caliper slide. Excellent value for money. SUPER PRICE! Low Cost Gas Soldering Iron This butane gas soldering iron features adjustable tip temperature and a foldout stand. Remove the soldering tip and you have a flame torch. Improved Model for 2007 Cat. TS-1111 $19.95 IP68 Nickle Plated Brass Cable Glands These nickel plated brass cable glands are certified to IP68 and are O-ring sealed against the ingress of dust, moisture and water to a depth of one metre. These glands are supplied complete with seals and locknuts. Five sizes are available. CAT. CABLE SIZE PRICE HP-0744 3 to 6.5mm $5.95 HP-0745 4 to 6mm $6.50 HP-0746 5 to 10mm $6.95 HP-0747 6 to 12mm $7.20 HP-0748 10 - 144 to 6mm $7.80 FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 Hand-Held Signal Generator INTERNET> www.jaycar.com.au Cat. TD-2081 $19.95 Auto Current Tester Simply plugs into any standard blade type fuse holder and provides an easy-to-read LCD of the circuit’s performance. The unit will measure up to 48V max, current 20A. With 400mm cable length. Cat. QP-2251 • Supplied with 12V A23 type battery • Measures 86(L) x 37(W) x 28.5(D)mm $29.95 OBD II LCD Scan Tool If you have a late model car, it will probably have an OBD (On-Board Diagnostics) connector. If it was manufactured after 1996, it will support the OBD II protocols. This OBD II Scan Tool supports the CAN (Controller Area Network) protocol and Can be used to check can be used to diagnose prior the VIN number on to repair and to verify Cat. QP-2294 late model cars! a repair after service. Better. More Technical $129.00 7 Refer: Silicon Chip May 2007 Accurately monitors audio signals to prevent signal clipping and ensure optimum recording levels. Programmable High Energy Ignition System Voltage Regulator Stereo VU/Peak Meter Refer: Silicon Chip May 2007 This handy voltage regulator can provide up to 1,000mA at any voltage from 1.3 to 22VDC. Ideal for experimental projects or as a mini bench power supply etc. Kit supplied with PCB & at. KC-5446 electronic $14.95 components. Short form kit. Case sold separately This unit is very responsive & uses two 16-segment bargraphs to display signal levels and transients peaks in real time. There are a number of display options to select, and both the signal threshold and signal-level calibration for each segment are adjustable. Kit supplied with PCBs, LCD and all electronic components. Accuracy within 1dB for signals above -40dB. • Requires 9V-12VDC power Cat. KC-5447 supply use: MP-3147 $17.95 $69.95 • Case not included use HB-6082 $9.95 DC Relay Switch Kit Refer: Silicon Chip November 2006 An extremely useful and versatile kit that enables you to use a tiny trigger current - as low as 400µA at 12V to switch up to 30A at 50VDC. It has an isolated input, and is suitable for a variety of triggering options. The kit includes PCB with overlay and all electronic components. Cat. KC-5434 $14.95 YOUR LOCAL JAYCAR STORE 50MHz Frequency Meter MkII Freecall Orders: Ph 1800 022 888 NEW SOUTH WALES Albury Ph (02) 6021 6788 Alexandria Ph (02) 9699 4699 Bankstown Ph (02) 9709 2822 Blacktown Ph (02) 9678 9669 Bondi Junction Ph (02) 9369 3899 Brookvale Ph (02) 9905 4130 Campbelltown Ph (02) 4620 7155 Erina Ph (02) 4365 3433 Gore Hill Ph (02) 9439 4799 Hornsby Ph (02) 9476 6221 Newcastle Ph (02) 4965 3799 Parramatta Ph (02) 9683 3377 Penrith Ph (02) 4721 8337 Silverwater Ph (02) 9741 8557 Sydney City Ph (02) 9267 1614 Taren Point Ph (02) 9531 7033 Tweed Heads Ph (07) 5524 6566 Wollongong Ph (02) 4226 7089 VICTORIA Coburg Ph (03) 9384 1811 Frankston Ph (03) 9781 4100 Geelong Ph (03) 5221 5800 Melbourne Ph (03) 9663 2030 Ringwood Ph (03) 9870 9053 Springvale Ph (03) 9547 1022 Sunshine Ph (03) 9310 8066 QUEENSLAND Aspley Ph (07) 3863 0099 Cairns Ph (07) 4041 6747 Ipswich Ph (07) 3282 5800 Mermaid Beach Ph (07) 5526 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 WESTERN AUSTRALIA Maddington Ph (08) 9493 4300 Northbridge Ph (08) 9328 8252 NORTHERN TERRITORY Darwin Ph (08) 8948 4043 NEW ZEALAND Christchurch Ph (03) 379 1662 Dunedin Ph (03) 471 7934 Glenfield Ph (09) 444 4628 Hamilton Ph (07) 846 0177 Manukau Ph (09) 263 6241 Newmarket Ph (09) 377 6421 Wellington Ph (04) 801 9005 Freecall Orders Ph 0800 452 9227 8 Ref: Silicon Chip February 2007 This compact, low cost 50MHz Frequency Meter is invaluable for servicing and diagnostics. This upgraded version features an automatic indication of units (Hz, kHz, Cat. KC-5440 MHz or GHz) and prescaler Improved model • 8 digit reading (LCD) • Prescaler switch $69.95 for 2007 • Autoranging Hz, kHz or MHz • 3 resolution modes including 10kHz rounding, 0.1Hz up to 150Hz, 1Hz up to 16MHz & 10Hz up to 16MHz • Powered by 5 x AA batteries or DC plugpack •Kit includes PCB with overlay, enclosure, LCD & all components. The 'Flexitimer' Ref: Electronics Australia March 1991 The kit uses a handful of components to accurately time intervals from a few seconds to a whole day. It can switch a number of different output devices and can be powered by a battery or mains plugpack. Kit includes PCB & all components. Requires 12- 15V DC (use Cat. MP-3006 $17.50 plugpack) Thousands Sold Digital Multimeter Kit Cat. KA-1732 $18.95 Refer: Silicon Chip March 2007 Ideal for two & four stroke engines. This system can be used to modify the factory ignition timing or as the basis for a standalone ignition system with variable ignition timing, electronic coil control & anti-knock sensing. • Timing retard & advance over a wide range • Suitable for single coil systems • Dwell adjustment • Optional coil driver • Single or dual mapping ranges Cat. KC-5442 • Max & min RPM adjustment $89.95 • Optional knock sensing • Supplied with PCB & all electronic components Add KC-5443 Ignition Coil Driver $44.50 & you’ll have a complete stand-alone ignition system that will trigger from a range of sources including points. Add the KC-5444 Knock Sensor for $16.95 and the unit will automatically retard the ignition timing if knocking is detected. Jacob's Ladder High Voltage Display Kit Mk II Refer: Silicon Chip April 2007 With this kit and the purchase of a 12V VN Commodore ignition coil (available from auto stores and parts recyclers), create an awesome rising ladder of noisy sparks that emit the recognizable smell of Ozone. This improved circuit is suited to modern high power ignition coils and will deliver a spectacular visual display that appears dangerous as indeed it is. Kit includes PCB, pre-cut wire and all electronic components. Cat. KC-5445 • 12V automotive ignition coil not included $39.95 • 12V car battery, SLA or >5A DC power supply required USB Experimenter's Interface Kit Interface your computer to the real world. There are five digital and two variable gain analogue inputs. Eight digital and two analogue outputs are available. Supplied with all components, silk screened PCB, Outstanding Educational Kits assembly manual and software. Learn everything there is to know about component recognition and basic electronics with this comprehensive kit. From test leads to solder, everything you need for the construction of this meter is included. All you'll Cat. KG-9250 need is a soldering iron! $19.95 • 67(W) x 123(H) x 25(D)mm Cat. KV-3600 $69.95 High Performance Electronic Projects for Cars Australia's leading electronics magazine Silicon Chip, has developed a range of projects for performance cars. There are 16 projects in total, ranging from devices for remapping fuel curves, to nitrous controllers and more! The book includes all instructions, components lists, colour pictures and circuit Cat. BS-5080 layouts. There are also chapters on engine management, advanced systems and DIY $19.80 modifications. Over 150 pages! All the projects are available in kit form. Smart Fuel Mixture Display This kit features auto dimming for night driving, emergency lean-out alarm, and better circuit protection. Another great feature is the 'dancing' display which operates when the ECU is operating in closed loop. Kit supplied with PCB and all electronic components. Cat. KC-5374 • Car must be fitted with air flow and EGO $27.95 sensors (standard on all EFI systems) for full functionality. Better. More Technical High Range Adjustable Temperature Switch with LCD It can be set anywhere up to 1200°C, so it's extremely versatile. The relay can be used to trigger an extra thermo fan on an intercooler or mount a sensor near your turbo manifold and trigger water spray cooling or a simple buzzer to warn of high temperature. Easily dash mounted the LCD displays the temperature constantly. FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 Cat. KC-5376 $69.95 Prices valid until June 30th 2007 INTERNET> www.jaycar.com.au PRODUCT SHOWCASE CREATOR Pro AV Products from Altronics Altronic Distributors has just been appointed Australian distributor for the CREATOR range of AV products. The range is extensive and has been well proven over the last 10 years and has been installed on many prestigious projects throughout Southeast Asia, Europe and USA. The range includes: • Touch screen control panels – capable of controlling any product with IR control. Ideal for boardrooms, home automation, lecture theatres, etc. • Latest technology video matrix switches – which offer a huge range of inputs and outputs and video formats. Combinations are available from basic 4-inputs to 4-outputs, though to massive 128-inputs to 128-outputs. Formats include composite video, VGA, RGB and RGBHV (with or without stereo audio), all with 3rd-party RS232 control. • Economical all-in-one education controllers – allowing easy control of AV equipment in classrooms and lecture theatres. • Distribution extenders and scalers – which convert one video format to another, various line drivers for extended cable runs, and converters/extenders to run video over Cat.5, coaxial cable or fibre for long cable runs. • State-of-the-art conference systems – for boardrooms, RS Components Gets Third Catalog Award RS Components, a leading distributor of electronic, electrical, electromechanical and industrial components, has been awarded the 2006 ‘Global Catalog Distributor of the Year’ Award from HARTING Technology Group – for the third consecutive year. This award recognises RS’s achievements in sales results for HARTING connectors and its focused approach to making the products accessible to customers worldwide through the RS Catalog and online. This follows on from RS Component’s achievement in winning the Environmental award at the Elektra 2006 European Electronics Industry award. Contact: RS Components 25 Pavesi St, Smithfield NSW 2164 Tel: 1300 656 636 Fax: 1300 656 696 Website: www.rsaustralia.com siliconchip.com.au council chambers, etc. Altronics will be stocking a comprehensive range of CREATOR’s popular models, which will increase with customer demand. Items not stocked Contact: should be avail- Altronic Distributors able within 7-10 174 Roe St, Perth, WA 6000 Tel: (08) 9428 2199 Fax: (08) 9428 2198 days Website: www.altronics.com.au Verbatim’s New Archival Grade DVD-R The new Archival Grade DVD-R 8x from Verbatim is manufactured using proprietary unique dual reflective layers, comprised of a silver layer for broad compatibility and a gold layer for long archival life. The highly reflective silver layer allows the UltraLife DVD-R disc to look like a standard silver disc to DVD drives and recorders. This provides a low initial error rate after recording, important for long archival life and the same drive read/write compatibility as standard silver-only discs. The gold reflective layer, naturally resistant to corrosion, prevents oxygen from coming through the DVD bonding material and corroding the silver reflective layer. Silver oxidation can be a primary factor which limits the lifetime of DVD media. As a result, the new Verbatim media shows significant improvements over conventional disks in terms of both longevity and compatibility. In addition, the Verbatim Archival Grade DVD-R media features Verbatim’s patented Advanced AZO recording dye and each disk is coated with the Verbatim Scratch Guard for additional protection against scratches. Verbatim UltraLife Gold Archival Grade DVD-R 8x discs are available in a 50 pack spindle from authorised Verbatim resellers nationally. Recommended retail is $116.95 (part number #95355). Contact: Verbatim Australia 6 Weir St, Glen Iris, Vic 3146 Tel: (03) 9823 0999 Fax: (03) 9824 7011 Website: www.verbatim.com.au TOROIDAL POWER TRANSFORMERS Manufactured in Australia Comprehensive data available Harbuch Electronics Pty Ltd 9/40 Leighton Pl. HORNSBY 2077 Ph (02) 9476-5854 Fax (02) 9476-3231 June 2007  57 Versatile 4- . . . with tone controls and This low-cost 4-input mixer features low-noise input preamps, each of which can be configured to suit a wide range of signal sources: microphones, guitar pick-ups, tape decks, synthesisers or CD players. Other features include a built-in equaliser with bass, midrange and treble controls along with a monitoring amplifier which can drive stereo headphones. By JIM ROWE 58  Silicon Chip siliconchip.com.au -Input Mixer a built-in headphone amp! Specifications Input Sensitivity (for 2.0 V RMS output, each ma in preamp configuration Dynamic mic, low impeda ): nce: ................................... ......................... 2.6mV RM Electric guitar: ................. S ........................................ ............................. 28mV Tape deck: ......................... RMS ........................................ ......................... 145mV RM CD player: ......................... S ........................................ ......................... 463mV RM S Frequency response: ..... ................ -3dB at 23Hz and 40kHz, -1dB at 40Hz and                    22kHz (with tone controls flat; see Fig.4) Maximum output: ............ ...................... 3.2V RMS (9V p-p) before clipping; see Fig.6 Output noise level (with respect to 2V RMS output , maximum gain & volum e, tone inated with 1kW, unweig hted 22Hz-22kHz bandw CD player input, ............... idth): ............... controls flat, inputs term ............ -92dB unweighte Tape deck input ............... d; -96dB A-weighted ............................ -92dB unweighted; -96dB A-weig Guitar input .................... hted ............................. -85dB unweighted; -89dB A-weig Low-Z mic input ................. hted ......................... -67dB unw eighted; -70dB A-weighte d Total harmonic distortio n (THD):.................. Less than 0.01% up to 3.2V RM S output Graphic equaliser: Bass: ......................... +13 dB & -12.5dB at 100Hz, ±18dB at 40Hz, ±0.5dB at Mid Range:...................... 1kHz ............ ±11dB at 1kHz, ±1d B at 100Hz, ±2.5dB at 10k Treble:............................. Hz ....... ±10.5dB at 12kHz, ±1d B at 1kHz, ±11.5dB at 15k Hz Headphone amplifier: Output voltage before clip ping: ............................5 90mV RMS into 2 x 33W THD for 500mV RMS into loads 2 x 33W loads: ................. .....................................0 .8% Supply voltage: ............... ........................................ ......... 12V DC (nominal) Maximum current drain: – see text ........................................ ........................................ ..... 45mA siliconchip.com.au June 2007  59 B ACK IN JANUARY 1992, we published the design for a low-cost four-input guitar mixer module for small bands and groups. It turned out to be very popular and the kit people tell us that kits for it were still selling steadily until quite recently. However, in its original form, it apparently wasn’t quite as flexible as many users wanted, particularly in terms of the ability to configure the input preamps for signal sources other than guitar pick-ups – eg, for dynamic mics, tape decks, CD players and synthesisers. It also didn’t include a built-in headphone amplifier for monitoring. These shortcomings have been eliminated in this new design. It retains all the features of the original January 1992 unit but there’s now more flexibility in configuring the input preamps, together with a built-in headphone amplifier. Block diagram Fig.1 shows the block diagram of our new Versatile 4-Input Mixer. As shown, it still provides four inputs, each with its own preamp stage and gain control. However, unlike the earlier design, each of the four input preamps can now be configured by the user, to provide the appropriate gain and input impedance values to suit a wide range of signal sources – from the millivolt or two of a low-impedance dynamic mic to the 1-2V signals of a CD/MP3 player or keyboard synthesiser. This makes the new unit much more versatile. Following the input gain controls, there’s a standard mixer stage, to allow the signals to be combined in whatever proportions you wish. The resulting composite audio signal is then fed to a 3-channel “mini equaliser” stage, where three tone controls (bass, mid-range and treble) allow you to adjust the tonal balance. This equaliser stage is basically an expanded version of a standard “Baxandall” feedback tone control, with three controls instead of two. From there, the output of the equaliser stage is passed to the master volume control and finally to the output jack via an output buffer amplifier operating with a gain of 2.2. This section is similar to the 1992 design but the headINPUT 1 phone amplifier (shown above the output buffer) is a new addition. It simply allows the output audio signal to be monitored via a pair of standard stereo headphones. The new design also differs from its predecessor in another way, not evident from Fig.1. The original unit needed a regulated power supply of ±15V DC but we’ve designed the new unit to operate from a single 12V DC supply. This can be provided either by a mains plugpack or a 12V battery, making the unit suitable for portable and mobile use. The current drain is less than 50mA. These additional features have been provided without sacrificing any of the key features of the original mixer. All components are still mounted on a single PC board for ease of assembly and although the board is a little larger than before, we’ve made it just the right size to fit snugly into a 225 x 165 x 40mm low-profile plastic instrument case. Circuit details Fig.3 (overleaf) shows all circuit details of the new mixer. It’s quite easy to relate each circuit section to its corresponding block in Fig.1. At the far lefthand side are the four signal input jacks CON1-CON4, each connected to its own preamp stage and gain control. These preamps each use one section of an LM833 low-noise dual op amp IC – ie, two ICs are used (IC1 & IC2). Although the four preamps shown in Fig.3 all have exactly the same circuit configuration, some of the components in each stage do not have specific values. Instead they have symbolic values like Rm, Rin, Rza, Rzb, Rf and Cf, to indicate their basic function rather than their value. This is because their values need to be chosen when each preamp is configured to suit a particular signal source. Specifically, Rm, Rin, Rza and Rzb are given values to provide the appropriate input impedance for the source, while Rf and Cf are given values to provide the appropriate gain and/or signal handling capability. The table in the circuit diagram gives the values for each of the various input sources. As the mixer is a mono device and there is a good chance that stereo devices may be connected to it (eg, an MP3 or PREAMP 1 GAIN (EACH CHANNEL) INPUT 2 TREBLE HEADPHONE AMPLIFIER MID RANGE PREAMP 2 MONITOR PHONES BASS INPUT 3 VOLUME PREAMP 3 OUTPUT TONE CONTROL (EQUALISER) MIXER/AMPLIFIER INPUT 4 OUTPUT BUFFER PREAMP 4 STEREO TO MONO MIXERS 60  Silicon Chip Fig.1: the block diagram of our new Versatile Mixer. The four inputs are amplified, mixed and then fed to the tone control/equaliser stage before passing to an output buffer, to be fed into an external power amplifier and/or a low-power headphone amplifier for monitoring. siliconchip.com.au Look mum, no wiring! This inside-thecase pic shows how everything is mounted on one PC board. It’s an early prototype so there are a few minor differences to the final design. CD player) all four channels have the capability of being “summed” to mono via Rma and Rmb – again, the values are shown in the table. Some devices, such as microphones, are generally mono, so Rma and Rmb may be substituted with links and/or omitted completely. Yes, we know there are stereo microphones out there but these are the exception, not the rule. For example, to configure a preamp for an electric guitar input, Rin, Rza and Rzb are 1MW (giving an input impedance of 330kW), while Rf is 22kW (to give a gain of 19 times, or about 25dB). Finally, Cf is given a value of 100pF to ensure stability. Similarly, to configure a preamp for the much higher stereo output from a CD player or synthesiser keyboard, Rza and Rzb are given values of 100kW while Rin is changed to 2.2kW. Rma and Rmb are given values of 47kW. These values give an input impedance of close to 50kW. Resistor Rf is made 27kW, lowering the preamp gain to unity so that it can handle the much larger input signals without overloading. Note that resistors Rza and Rzb must always have the same value. That’s because they also form the bias voltage divider for the preamp concerned. No provision has been made for powering electret microphones but in a permanent installation, this could be easily achieved through the use of a suitable bias resistor (10kW is commonly used) from the nominal 12V line to the “hot” input of the electret. The outputs from the preamp stages are fed via 2.2mF capacitors to gain control potentiometers VR1-VR4. The signals at the wipers are then fed via 47kW mixing resistors and a 2.2mF capacitor to the pin 2 input of mixer/amplifier stage IC3a. IC3a operates as a standard inverting amplifier with a gain of -2 (100kW/47kW) for each of the four inputs. It also provides a low “virtual earth” input impedance, to ensure that there is no interaction between the four gain controls (VR1-VR4). siliconchip.com.au A half-supply rail bias (+6V) for IC3a is provided by op amp IC3b. This is connected as a voltage follower with its pin 5 input set at +6V by a voltage divider consisting of two 47kW resistors across the supply rail. The resulting +6V bias voltage from pin 7 of IC3b is applied to pin 3 of IC3a via a 100kW resistor. It’s also used to bias op amps IC4a (pin 3) & IC4b (pin 5). Tone control stage IC4a forms the heart of the tone control/equaliser stage. As mentioned previously, this is an extended version of the standard Baxandall feedback tone control configuration – ie, it has three controls instead of the usual two. The operation is exactly the same though, with each pot (VR5, VR6 & VR7) acting as a gain control for signals within a set frequency range. Fig.2: this shows the operation of the bass tone control stage. June 2007  61 +12V Rm1a INPUT 1 Rm1b CON1 47 F Rza1 2.2 F Rin1 1k Rzb1 5 6 8 7 IC1b 1.2k 8 5 2.2 F GAIN 1 VR1 10k LOG Rf1 100nF 47k 47k 47 F 47k 7 IC3b 6 +6V SUPPLY RAIL SPLITTER Cf1 PREAMP 1 22 F 100k Rm2a INPUT 2 Rm2b CON2 Rza2 2.2 F Rin2 1k Rzb2 2.2 F 3 2 4 1 IC1a 1.2k 4 47k 2.2 F 100k Cf2 22pF PREAMP 2 22 F MIXER/AMPLIFIER STAGE (A = -2) +12V Rm3a INPUT 3 Rm3b CON3 47 F Rza3 2.2 F Rin3 1k Rzb3 2.2 F 1 IC3a 2 GAIN 2 VR2 10k LOG Rf2 3 2.2 F 5 6 8 7 IC2b GAIN 3 VR3 10k LOG Rf3 1.2k 2.2 F 47k IC1– IC4: LM833 IC5: LM358 4 8 1 Cf3 PREAMP 3 22 F K LED Rm4a INPUT 4 Rm4b CON4 Rin4 1k Rzb4 1.2k 22 F SC  2007 3 2 4 1 IC2a A 2.2 F GAIN 4 VR4 10k LOG Cf4 PREAMP 4 VERSATILE FOUR INPUT MIXER In operation, the pots vary the effective negative feedback ratios for their respective frequency bands. Fig.2 shows a simplified scheme for the bass control. When the pot is in its centre position, IC4a has equal input and feedback impedances for the frequencies in its control 62  Silicon Chip E B C Rza4 2.2 F Rf4 CON1-4 ALL STEREO SWITCHED TYPE BC328, BC338 A 47k D1, D2: 1N4148 K ZD1 + PREAMP COMPONENT VALUES FOR VARIOUS INPUTS Rma Rmb Rin Rza,Rzb Rf Cf ELECTRIC GUITAR (50mV) (OMIT) LINK 1M 1M 22k 100pF DYNAMIC MIC (Mono, Lo-Z) (OMIT) LINK 680 10k 220k 12pF DYNAMIC MIC (Mono, Hi-Z) (OMIT) LINK 1M 100k 120k 18pF TAPE DECK (Stereo, 300mV) 47k 47k 2.2k 100k 82k 22pF CD PLAYER/SYNTH (St, 2V) 47k 47k 2.2k 100k 27k 82pF INPUT range, thus giving it unity gain for those frequencies. However, when the pot is turned to the “maximum boost” (fully clockwise) position, the ratio of the feedback and input impedances increases to 11:1 (110kW/10kW), so the stage gain for those frequencies increases to 11 times or +21dB. siliconchip.com.au 47 +12V 4.7k 2200 F 25V 1000 F 16V A +6V CON7 A K 100k LIN 33 10 F 10k VR5 BASS 10k ZD1 16V 1W +12V K  LED1 22nF 10k 10 100nF 2.2nF 10k 10k 100k LIN 6.8k 100k LIN 1.5nF TONE CONTROL (EQUALISER) STAGE 5 2.2 F VR6 MIDRANGE 10nF 6 6.8k 8 470 VOLUME VR8 10k LOG VR7 TREBLE 39pF 7 IC4b 2.2 F 100 OUTPUT CON5 68pF 4.7 F 10k 22k 100 OUTPUT BUFFER (A = -2.2) 2 +6V 1 IC4a 3 4 100nF +12V 2200 F 16V 10k 4.7pF B 330k PHONES VOLUME VR9 50k LOG 100k A 47k 270nF 2 6 10 F 8 IC5b 7 100k +6V 33 470 F K 1 4 330k K 68 PHONES CON6 A 33 D2 270nF SUPPLY RAIL SPLITTER IC5a Q1 BC338 E D1 3 5 C B E C 10k 68 Q2 BC328 HEADPHONE AMPLIFIER Fig.3: don’t be daunted by the size of the circuit diagram – it really is quite an easy project to understand (especially when you compare it to the block diagram overleaf). And the good news is it’s even easier to put together because all components mount on a single PC board. No wiring should mean no mistakes. Conversely, when the pot is turned to the “maximum cut” (fully anticlockwise) position, the ratio of feedback and input impedances reduces to 1:11 (10kW/110kW). As a result, the stage no longer amplifies those frequencies but attenuates them instead – ie, by about 11 times, or -21dB. siliconchip.com.au Going back to Fig.3, all three tone controls act in this same way but each covers its own range of frequencies, as determined by the values of the various capacitors in the feedback networks. IC4a’s output appears at pin 1 and is AC-coupled to June 2007  63 AUDIO PRECISION SCFREQRE AMPL(dBr) vs FREQ(Hz) 25.000 24 APR 2007 17:43:54 20.000 u 15.000 10.000 x w 5.0000 v 0.0 -5.000 y -10.00 -15.00 -20.00 -25.00 10 100 1k 10k 100k Fig.4: this complex frequency plot is the result of five frequency sweeps with different tone control settings. The green trace u is taken with maximum bass boost, midrange flat (centred) and maximum treble cut. The yellow trace v is taken with all tone controls flat (centred). The red trace w is taken with maximum bass cut, midrange flat (centred) and maximum treble boost. The purple trace x is taken with bass and treble controls flat and maximum midrange boost while the pink trace y is taken with bass and treble controls flat and maximum midrange cut. Note that the tone controls do interact with each other. VR8, which is the master volume control. This controls the signal level fed to output buffer stage IC4b which is configured as a standard inverting amplifier with a gain of 2.2 (22kW/10kW). Its output is in turn fed to output jack CON5 via a 2.2mF DC blocking capacitor. Headphone amplifier The output signal at CON5 is also used to feed the headphone amplifier (IC5a), via a 100W isolating resistor and potentiometer VR9 (the headphone volume control). The headphone amplifier itself is based on IC5a, which is half of an LM358 low-power dual op amp. IC5b is wired in a similar manner to IC3b (ie, as a voltage follower) and is used to bias pin 3 of IC5a to +6V. Transistors Q1 and Q2 are used to boost the output current capability of IC5a, to provide sufficient drive for both sides of a standard low-impedance stereo headphones/ear buds (33W per earpiece). These transistors are configured as complementary emitter followers, with diodes D1 and D2 setting their quiescent bias levels. Negative feedback for the stage is taken from the junction of the two 33W emitter resistors and applied to pin 2 of IC5a via a 330kW resistor, ie, transistors Q1 & Q2 are inside the feedback loop. This reduces the distortion level of the headphone amplifier and also flattens its frequency response. The 4.7pF capacitor across the 330kW resistor rolls off the response above 100kHz to ensure stability. Power supply To make it as versatile as possible, power for the mixer is derived from either an external 12V DC regulated plugpack supply or from a 12V battery. This is applied via connector CON7 and powers all the mixer circuitry. Reverse polarity protection is not provided by a series 64  Silicon Chip diode but instead by a 10W series resistor and zener diode ZD1, which also protects the circuit from over-voltage damage. If you connect a plugpack with the wrong polarity (ie, centre negative instead of the more usual centre positive) the 10W resistor should burn out, cutting power from the circuit. A single 3mm “power on” high-brightness LED connects across the 12V supply via a 4.7kW current-limiting resistor. The 2200mF capacitor across ZD1 decouples and filters the supply rail, while the rail to the headphone amplifier is further decoupled using a separate 33W resistor and 2200mF capacitor. This is done to prevent unwanted interaction between the headphone amplifier and the rest of the circuit due to supply rail fluctuations. Additional supply decoupling for the +12V rail to the LM833 op amps is provided by a 47W resistor and 1000mF capacitor. This eliminates any possibility of low frequency “motor-boating” when high gain is used on all the input channels, together with maximum bass boost. It also makes it possible to use an unregulated 9V DC plugpack in a pinch; hum will be higher but at least it might get you out of trouble if the specified regulated 12V DC plugpack is unavailable. Self-contained battery power? We know it’s going to be asked, so we will answer the question already: can you make the mixer portable and run it from internal batteries – say a couple of 9V alkalines? The answer, with a couple of reservations, is yes, it is possible – because the op amps set up the half-supply rails. The two batteries could occupy the vacant real estate in the middle of the PC board. (You’d obviously need to fix these in position to the PC board but that shouldn’t be difficult, given the amount of earth track in this area). A couple of riders, though: the mixer draws about 20mA without the headphone amplifier being used, so even new alkaline 9V batteries are only likely to give you a few hours operation at best. If you use the headphone amp, expect even less. But that period might be long enough for your application. And to use an 18V supply, you would need to change the 16V zener to a 22V type. You would also probably want to fit a small power switch. Construction Another of the major features of this new design, one that we haven’t mentioned earlier, is the fact there is no wiring to be done! Everything – including the input/output sockets and control pots – is mounted on the single PC board. This makes building this mixer very easy. This PC board is coded 01106071, measures 198 x 156mm and fits neatly inside a standard low-profile ABS instrument case measuring 225 x 165 x 40mm (available from Jaycar and Altronics). As can be seen from the photos, all but one of the control pots are mounted along the front of the board, the exception being the headphone volume control pot (VR9). There simply wasn’t enough room for it on the front, so it was mounted adjacent to headphone jack (CON6) on the rear panel. siliconchip.com.au AUDIO PRECISION SCTHD-HZ THD+N(%) vs FREQ(Hz) 5 26 APR 2007 10:16:22 Parts List – Versatile 4-Channel Mixer 1 1 PC board, code 01106071, 198 x 156mm 6 6.35mm stereo jack sockets, PC board mounting (CON1-6) [eg, Jaycar PS-0190, Altronics P-0073] 1 2.5mm concentric DC socket, PC-mount (CON7) 9 16mm diameter aluminium knobs 5 8-pin DIL sockets (for IC1-IC5) 1 200mm length of 0.25mm tinned copper wire 1 Low profile ABS instrument case, 225 x 165 x 40mm (eg Jaycar HB-5972, Altronics H0474) 0.1 0.010 0.001 20 100 1k 10k 20k Fig.5: this graph shows total harmonic distortion versus frequency at an output of 2V RMS. The measurement bandwidth is 22Hz to 80kHz. AUDIO PRECISION SCTHD-W THD+N(%) vs measured 5 LEVEL(V) 26 APR 2007 10:11:38 1 0.1 0.010 0.001 10m 0.1 1 5 Fig.6 shows total harmonic distortion versus output level at a frequency of 1kHz. The measurement bandwidth is 22Hz to 22kHz. The rising value at lower signal levels is solely due to the residual noise at around –92dB with respect to 2V. Since the residual noise is fixed, it results in higher THD values as the signal level is reduced. In reality, the harmonic distortion is less than .003% at 1kHz, for all signal levels up to 2V RMS. Note that the board has been designed to suit standard low-cost 6.35mm jacks for CON1-CON6 (like the Jaycar PS-0190/Altronics P-0073) but the board will also accept the unswitched stereo type. The reason we use switched stereo sockets is so that unused inputs are shorted to earth, thus minimising noise. Fig.7 shows the parts layout on the PC board. Begin by carefully inspecting the PC board for etching defects, then start the assembly by fitting the six wire links. Follow these with the resistors. You will have to decide how you wish to configure each input and then choose resistors Rma, Rmb, Rin, Rza, Rzb and Rf from the table on the circuit diagram accordingly. We’ve shown the resistor colour codes (and capacitor codes) but you should also check the resistor values using a digital multimeter, as some colours can be difficult to decipher. siliconchip.com.au Semiconductors 4 LM833 dual low noise op amp (IC1-IC4) 1 LM358 dual op amp (IC5) 1 BC338 NPN transistor (Q1) 1 BC328 PNP transistor (Q2) 1 16V 1W zener diode (ZD1) 1 3mm high-brightness LED (LED1) 2 1N4148 diodes (D1,D2) Capacitors 2 2200mF 25V RB electrolytic 1 1000mF 25V RB electrolytic 1 470mF 25V RB electrolytic 4 47mF 16V RB electrolytic 4 22mF 16V RB electrolytic 2 10mF 16V RB electrolytic 1 4.7mF 16V RB electrolytic 13 2.2mF 16V RB electrolytic 2 270nF MKT metallised polyester 3 100nF multilayer monolithic 1 22nF metallised polyester 1 10nF metallised polyester 1 2.2nF metallised polyester 1 1.5nF metallised polyester 1 68pF disc ceramic, NPO 1 39pF disc ceramic, NPO 1 22pF disc ceramic, NPO 1 4.7pF disc ceramic, NPO 4 ceramic caps, selected values (Cf1-Cf4) Resistors (1%, 0.25W) 2 330kW 4 100kW 2 6.8kW 1 4.7kW 1 100W 2 68W 7 47kW 4 1.2kW 3 33W 1 22kW 4 1kW 1 47W 8 10kW 1 470W 1 10W Up to 8 47kW input mixer resistors, (Rm1-4 and Rmb1-4) [omit for mono sources and use some links instead] 4 input resistors, selected values (Rin1-Rin4) 8 bias divider resistors, selected values (Rza1-Rza4 & Rzb1-Rzb4) 4 feedback resistors, selected values (Rf1-Rf4) 4 ceramic capacitors, selected values (Cf1-Cf4) Potentiometers 5 PC-mount 16mm 10kW log pots (VR1-VR4,VR8) 3 PC-mount 16mm 100kW linear pot (VR5-VR7) 1 PC-mount 16mm 50kW log pot (VR9) June 2007  65 Fig.7: here’s how it all goes together. Don’t worry about all that PC board real estate with not much on it – the size is basically dictated by the pot spacing and the availability of suitable cases! The MKT and non-polarised capacitors can go in next. Again, the feedback capacitors (Cf1-Cf4) will have to be selected from the circuit diagram table. The polarised electrolytics can then be fitted, taking care to ensure they go in with the correct polarity. Next fit the sockets for the five ICs, making sure you orientate them with their “notched” ends as shown in Fig.7 (above). Follow these with diodes D1 & D2, zener diode ZD1 and transistors Q1 & Q2, again making sure they have 66  Silicon Chip the correct orientation. Potentiometers VR1-VR9 can now be fitted. Before doing so, though, cut each pot’s spindle to a length of 10mm using a small hacksaw and then use a small file to remove any burrs. This step will not be necessary if you use “metric” pots with 10mm-long splined shafts and matching splined knobs. Note that the three 100kW linear units (usually marked “B100K”) must be fitted in the VR5, VR6 & VR7 positions siliconchip.com.au And here’s the matching completed PC board photo, shown very close to full size (again, this early prototype has some minor component placement differences). This is ready to “drop into” the ABS case. along the front of the board. The five 10kW log pots (marked “A10K”) go in positions VR1-VR4 and VR8, while the remaining 50kW log pot (marked “A50K”) is fitted as VR9 at the rear. It’s just a matter of pushing each pot as far down onto the board as it will go and soldering its pins. Once they’re all in, scrape or file away some of the plating at the top of each of the VR1-VR8 pot bodies and solder them together using a 170mm length of tinned copper siliconchip.com.au wire. A second length of tinned copper wire is then used to connect VR3’s body to an adjacent earth point on the PC board – see Fig.7. This step earths the pot bodies to prevent hand capacitance effects as the controls are adjusted. The seven 6.35mm jack sockets CON1-CON7 are fitted along the rear in much the same way, except there is no earth wire to be soldered on. Once the sockets have all been fitted, the next step June 2007  67 www.siliconchip.com.au INPUT 1 SILICON CHIP VERSATILE MIXER – SILICON CHIP VERSATILE MIXER 12V DC IN PHONES VOL PHONES OUTPUT – INPUT 4 + – INPUT 3 + INPUT 2 + VOLUME TREBLE MIDRANGE BASS INPUT 4 INPUT 3 INPUT 2 INPUT 1 Front (left) and rear panels for the Versatile Mixer. The white panels underneath each input pot are used for writing on the input source (using a fine felt-tipped pen) – especially if your mixer is not permanently installed (and even if it is). Instantly knowing which input is which can save a lot of embarrassment when you need to adjust levels! 68  Silicon Chip is to attach the rear panel to them (and to VR9). This simply involves passing the threaded ferrules through their matching panel holes and then fitting the washers and nuts. Don’t tighten the nuts up fully yet though – just leave them “finger tight” for the time being. The front panel is fitted in exactly the same way, this time over the threaded ferrules of VR1-VR8. Again leave the pot nuts finger tight – they’re not fully tightened until the assembly is fitted into the case. Once this has been done, you’re now ready to slide the completed board/panel assembly down into the lower half of the case, with the panel ends mating with the front and rear case slots. That done, the PC board can be fastened to the integral standoffs on the base using nine of the small self-tapping screws provided. The connector and pot mounting nuts can now all be carefully tightened with a small shifting spanner. Don’t tighten them too forcefully though, otherwise you’ll strip the threads. Just nip them up tight enough to ensure they don’t loosen with use. That done, you can fit the control knobs to the pot spindles. The “power on” LED mounts so its front is flush with the front panel – a tiny dob of super glue is enough to hold it in place. The LED leads will probably not be long enough to reach down to their respective holes on the PC board so use some resistor lead cut-offs to lengthen them. If there is any danger of shorting the LED leads to the potentiomenter earthing wire, you can slip some short lengths of insulation over the leads. There’s now just one more step to complete the construction and that’s to plug the five ICs into their sockets. Be sure to fit the LM358 into the IC5 position and take care to ensure that they are correctly orientated (IC1 & IC2 face in one direction, while IC3, IC4 & IC5 face in the opposite direction). Checking it out There are no circuit adjustments to be made but you should give it a quick visual check-out to make sure everything is in the right place and you haven’t, for example, put any of the ICs, other semiconductors or electrolytic capacitors in backto-front. If it all checks out, you should make a simple current check before pronouncing it ready for use. This is easy to do – you actually do it by measuring voltage! First, turn control pots VR1-VR4, VR8 and VR9 fully anticlockwise and set VR5-VR7 to the centre of their ranges (ie, at the top). That done, connect a 12V DC power supply to the mixer’s power socket. Make sure the power supply plug’s centre pin is positive, otherwise the 10W resistor will let its smoke out and the mixer will definitely not work. Now turn on the power supply and make sure the front panel LED comes on. That’s a pretty good clue that everything is working properly. But it’s not foolproof! Connect your multimeter, on its lowest voltage range, across the 10W resistor at the DC input socket on the PC board. It should read somewhere between 200 and 300mV (200mV across the 10W resistor means that the mixer is drawing 20mA). If so, you can be reasonably confident your mixer is working properly. However, if the reading is higher than 300mV, switch off immediately because this indicates that there’s some kind of error. At least you can be assured that it isn’t a wiring error because there is no wiring! So what is wrong? There are quite a few possibilities – you may have connected the siliconchip.com.au DC power lead with reversed polarity, fitted one of the ICs, transistors, diodes or electrolytic capacitors the wrong way around, or accidentally shorted adjacent tracks or pads on the PC board with solder. (Kit suppliers tell us that 99% of problems are due to poor soldering.) In that case, it’s a matter of going over your work and carefully checking everything until you find the problem. As we mentioned earlier, if you have reversed the power supply polarity, the odds are that the 10W resistor at the input (ie, between the power input socket and the zener diode) will have said “too much” and given up the ghost. Assuming that the voltage across the 10W resistor is correct (at 200-300mV), switch the multimeter to a suitable DC voltage range (eg, 0-20V) and use it to check the voltage at various key points in the circuit. The easiest way to do this is to connect the meter’s negative lead to the wire earthing the pot bodies and then use the positive lead to probe the key voltages. Remember that you have many identical stages to compare voltages. First, check the voltage at the rear centre pin of CON7 - it should read 12V, or whatever your battery or power supply is delivering. That done, check that pin 8 of either IC4 or IC3 is about 1V lower. You should also find this voltage at pin 8 of IC1 and IC2 as well. Now check the voltage at pin 8 of IC5. This will be slightly lower again – something like 11.8V or so, if you’re using a 12V source. If everything seems OK so far, check the voltages at pin 7 of IC5 and at pin 7 of IC3. In both cases, you should get a reading of about 5.5V, because these pins are the outputs of the “half supply rail” splitters. If these voltages are correct as well, your mixer is almost certainly working correctly. It’s just about finished! The last check is to wind down the headphone volume pot to minimum, connect a set of headphones and then slowly increase the level to maximum. Depending on the headphone sensitivity, at maxiNo. Value o 2 330kW Capacitor Codes o 4 100kW o 7 47kW Value mF code EIA Code IEC Code o 8 10kW 270nF 0.27mF 274 270n o 2 6.8kW 100nF 0.1mF 104 100n o 1 4.7kW 22nF .022mF 223   22n o 4 1.2kW 10nF .01mF 103   10n o 4 1kW 2.2nF .0022mF 222   2n2 o 2 470W 1.5nF .0015mF 152   1n5 o 1 100W 68pF NA   68   68p o 2 68W 39pF NA   39   39p o 3 33W 22pF NA   22   22p o 1 10W 4.7pF NA   4.7   4p7 siliconchip.com.au This inside view from the back shows the input and output sockets, ’phones volume control, DC input plus the internals of the front panel. mum you will probably hear some hiss or noise but not much else. Plug in a suitable signal source (taking into account what components you have selected for the various inputs) and make sure that the input level pot for that source varies the level from zero to maximum. Check all four inputs in a similar way with other audio sources and also make sure that there is output at the output socket by connecting it to an amplifier. All that remains is to fit the top half of the case and fasten everything together using the four countersink head machine screws supplied. Your mixer is now complete and SC ready for use. Resistor Colour Codes 4-Band Code (1%) orange orange yellow brown brown black yellow brown yellow violet orange brown brown black orange brown blue grey red brown yellow violet red brown brown red red brown brown black red brown yellow violet brown brown brown black brown brown blue grey black brown orange orange brown brown brown black black brown 5-Band Code (1%) orange orange black orange brown brown black black orange brown yellow violet black red brown brown black black red brown blue grey black brown brown yellow violet black brown brown brown red black brown brown brown black black brown brown yellow violet black black brown brown black black black brown blue grey black gold brown orange orange black gold brown brown black black gold brown June 2007  69 SERVICEMAN'S LOG The need to eat and pay bills The need to eat and pay bills often forces me to take on jobs I’d rather not do – like fixing computers. But first, let’s look at some TV set repairs. Most problems associated with the loss of just one colour are reasonably easy to diagnose. Usually, they are around the colour output stages to the CRT. Recently, I had a 2003 Sharp SX68NF8 (GB-1 chassis) come in with the client complaining that it had a pink picture. Because colour TV uses an additive colour system, this meant it was losing green. Sure enough, the voltage on the green cathode of the CRT was high. This was actually a relief because if it had been the same as the other two guns, it could have meant that the green gun was low in emission. By contrast, the PWB-B voltages on connector KY to the CRT board were all correct, with the green input being 3.2V. The circuit is really very straightforward, with the R, G and B inputs going to the video output IC (IC850, TDA6103Q) and its outputs going directly to the CRT cathodes. The latter operate at +210V via high speed diodes but these diodes all measured OK out of circuit. Naturally, I suspected the IC as the culprit and quickly whipped in a new one. Unbelievably, I was wrong but it wasn’t the first time in my life! The symptom remained the same but the circuit was so simple that there was nothing much left to test. Well, of course there was one significant feature I haven’t mentioned. There is feedback from the output to the input via two resistors in parallel – R875 (120kW) and R857 (220kW). R875 measured OK out of circuit but R857 had gone very high. Replacing it restored the green to the picture. If only they were all that easy! Purity problem A Grundig Elegance 82 MW82-15018 Dolby (CUC1935 chassis) was intermittently suffering from colour purity patches. These blobs of colour were in the corners and had only started to occur after an electrical storm. When I got to look at the problem, I quickly came to the conclusion that the set’s degaussing circuit wasn’t working 70  Silicon Chip correctly and decided to replace the 3-pin PTC resistor R22501. The colour problems were easy to see before I did the job and were completely gone after I had finished, so I naturally concluded that my diagnosis had been correct. However, I was wrong again – the set boomeranged the very next day with the same symptoms. I now did what I should have done last time and carefully examined the old PTC. When I shook it, it didn’t rattle and when I removed the cover the discs inside were like brand new. There was nothing for it but to admit that I had definitely misdiagnosed. Degaussing circuits these days are all different, and this one was controlled by a Triac. That was in turn controlled by the main microprocessor via an optocoupler. I removed the Triac (TC22503) and checked it on my tester. It was a BTB08-600CW and it read perfectly as did the optocoupler (OPTK22505). There are no details in the manual on how this circuit operates but I suspect it only degausses from standby to on and that are no menus that allow it to be manually operated. My problem was that it was working correctly for 99% of the time. So what was causing it to fail for the remaining 1% and how could I prove it? Well I regret to say that life is too short to come up with those sorts of answers. The client needed his set back and I needed his money. The problem could have been due to a faulty EEPROM or microprocessor which was switching the degauss circuit on and off incorrectly but there just wasn’t time to find out. During my inspections of the PC board, I noticed that it had been drilled to take a link (BR22503). This links the A1 and A2 terminals of the Triac, so I removed the Triac and soldered the link into position. What this does is make the set only degauss when it is switched on from cold – like most colour TV sets do. siliconchip.com.au This is the picture that was displayed by a faulty Panasonic TC-51FM52A TV set. Where do you start with something like this? My modification may have effectively bypassed one of the sophisticated parts of this set but at least it now demagnetises properly. LCD colour purity You don’t expect purity colour problems with LCD displays but they can happen and unfortunately there isn’t a lot you can do about it. One 3-year old Philips LCD receiver came in with a pink fringe all the way around the edges, due to the way the display was mounted in its frame. Unfortunately, the fix was either a new display or a new set. My own Acer computer monitor has two very small patches at the bottom, which are due to the mounting screws creating pressure on the display in those locations. Loosening them a little improved it a lot but it’s still not perfect. Intermittent Panasonic I recently had a Panasonic Wide- siliconchip.com.au screen TX-76 PW10A come in for repairs. This set employs a EURO 7C chassis and it had an extremely intermittent no-picture problem when it was cold. However, it was OK once it had warmed up. If the set was disturbed during the warm-up period or the chassis tapped, the picture would come and go on an intermittent basis – similar to the effects produced by a dry joint. As a result, I removed the chassis and poured over it, looking for this elusive dry joint. I found nothing so I then swapped a few of the boards over until I isolated the problem to Board A. Next, I tried heating and freezing but I just couldn’t quite nail it – at least not initially. Eventually, I found that IC2708, a 5-pin 9V voltage regulator, was the culprit and you could watch its output voltage coming and going on the meter. I ordered a new one but it was only when I removed the old one that its secret was revealed. When the set had been manufactured, one of the regulator’s pins had been bent and didn’t go right through its hole in the PC board. As a result, it was only just touching the solder pad on the other side. Straightening the pin and resoldering it fixed the problem. An elderly Panasonic An elderly Panasonic TC-51FM52A with an MX3 chassis came in with such a weird picture that I just had to take a photograph and share it with you. With a picture like this, where would you start? Well, it actually had two problems Items Covered This Month • Sharp SX68NF8 TV set (GB-1 chassis) • Grundig Elegance 82 MW8215018 Dolby TV set (CUC1935 chassis) • Panasonic TX-76 PW10A widescreen TV set (EURO 7C chassis) • Panasonic TC-51FM52A TV set (MX3 chassis) • Dell mini tower computer (Pentium 4 2.8GHz) • Toshiba Satellite 2750 DVD/6.0 notebook computer (PS275A-4K986) • • • Palsonic CTV5160G TV set Telefunken TTV-29D TV set Panasonic TC-29V26A M16 TV set – one of which, sadly, was fatal as far as the set was concerned. The first problem was caused by a lead that had corroded off the vertical deflection yoke where it was exposed to the brown glue. And the second problem? Well, that was a colour purity problem that was due to the shadow mask moving when the set was accidentally dropped. Of course, no mention was made of that catastrophe until afterwards! Another photograph shows a Panasonic M16 Remote Control that somehow got mangled in a “Z” bed June 2007  71 Serviceman’s Log – continued when it was folded up. The owner’s comment was “But surely you can fix this?”! Computer virus I avoid fixing computers if I can. The fact is, many home computer systems are a complete mess within a few months of purchase, especially if children are involved. However, sometimes I need the money and so I reluctantly agreed to look at an 18-month old Dell mini tower. This was a Pentium 4 2.8GHz machine running Windows XP Home SP2. It was regularly crashing to the blue screen of death and dumping memory, to the point where it had almost become unusable. So was this a hardware or a software problem? To find out, the first thing I did was to run a few diagnostics from a bootable floppy. Using this, I checked the RAM, after which I established that the BIOS was correctly configured. 72  Silicon Chip Next, I disconnected any hardware that wasn’t necessary for the machine to boot, such as the CD ROM and the floppy drive but the problem was still there. Eventually, however, I managed to get it running long enough to set up a full CHKDSK on the next boot and to switch MSCONFIG.EXE into the diagnostic mode (this switches off all TSRs on startup). This told me that there was nothing wrong with the hard disk and that there was probably no problem with the hardware, as the computer was now seemingly working properly. At this stage, I ran a few more utilities to clean-up the registry and did a disk clean-up (I made a copy of the deleted files) and defrag for good measure. However, when I re-enabled the normal start-up in MSCONFIG. EXE, the computer immediately began crashing again. Each time this happened, I had been making a note of what the computer had been trying to do at the time and what error messages were appearing on the screen. I soon realised that it was frequently crashing as it was trying to install several Microsoft Updates which had already been downloaded. These were KB932330 (for Outlook 2003), KB890830 (malicious software) and KB931784 (security update). In addition, I noticed that a couple of files were mentioned with error addresses, namely LZX32.sys and Kmixer.sys. Using an excellent file manager called ZTree (an up-to-date version of the old XTree Gold for DOS), I searched for LZX32.sys. The beauty about this particular file manager is that it lets you see all the files warts and all, including hidden and system. However, despite a global search, there was no sign of this file. By contrast, I did find Kmixer.sys but could not decide on its significance as it is an audio mixer driver file. So why would the computer indicate an error with a file that supposedly didn’t exist on the hard disk? I had no idea so I accessed the Internet using my own computer and searched for LZX32.sys using Google. And that’s when it all fell into place. There were hits all over the page and all of them labelled LZX32.sys as spyware or malware, or as a Trojan virus. This Trojan is camouflaged and can also be called PE386, Rustock.b, MSguard, LXZ32 and Kmixer, amongst others. To kill it, I downloaded a free file called RUSTBFIX.EXE and copied it to the sick computer. I ran it and that got rid of the virus. But why did it happen? The computer was running an up-to-date antivirus program and had its firewall and automatic updates switched on. I think the clue is that it hit before or the installation the Microsoft security updates that were designed to stop it and the source was probably via Mes- siliconchip.com.au senger or chatrooms, which were heavily used by the machine’s owner. Anyway, that completely fixed the computer and I suggested to the owner that he get himself some antispyware software like Ad-aware and possibly a copy of Windows Defender Beta 2 which you can download free off the net. CIRCUIT ! W E N WIZARD A revolutionary new system that combines circuit design, PCB design, simulation & CAD/ CAM in one complete package for your pc. Another computer I had a Toshiba Satellite 2750 DVD/6.0 Notebook (PS275A-4K986) come in with its owner complaining there was no display. When I looked at it, you could sometimes see faint lines or a part of the picture. And when I applied slight pressure to the screen, I could restore more of it. Eventually I found a spot where I could squeeze the LCD and it would display the whole picture perfectly. However, when I released this pressure, the picture would slowly fade away. Dismantling notebooks is always tricky, especially when it comes to the display. Eventually, I managed to get it apart but could see nothing physically wrong with the Sharp display panel used. What I did notice, however, was a flexible PC board with surface-mount ICs and transistors. And although I could see no cracks or tears in it, this was mounted right near the place I had been squeezing to restore the picture. Unfortunately, there are no parts here that can be replaced – only a new panel would fix the problem. I explained this to the client and also explained that the computer could still be used with an external monitor. I also backed up all the data on his hard drive to a 2GB USB flash drive, so that he could easily transfer it over to a new computer. However, that was easier said than done because the notebook was using Windows 98SE which doesn’t fully support USB. Fortunately, I managed to obtain the correct software to make it work. rom: f o m e d e a fre oncepts.com d a o l n w o D ave-c w w e n . w ww rsions click To see the s between difference ssional ve ard & Profe s’. on ‘feature Stand IDEAL FOR Schools, TAFEs, Hobbyists & Business Circuit Wizard Standard – $202* & Circuit Wizard Pro – $390*post*incin GST Aust. 555Electronics Australia and New Zealand – for orders or more information, please contact McLaren Vale, SA 5171 Tel (08) 8323 8442 email: bwigley<at>senet.com.au www.555electronics.com.au POSITION VACANT Research & Development Engineer Entertainment Technology Insurance jobs Small TV sets usually just aren’t worth looking at. However, I do make an exception for insurance companies who insist you call and check out any sets that are the subject of an insurance claim. Usually, by the time you’ve done that, they are reluctant not to get it completely fixed, otherwise they would lose the call-out and quotation fee. God bless accountants! Recently, I had to attend to a Palsonic CTV5160G 20inch television set that had been damaged by a lightning strike during a storm. Replacing this set would not have cost much more than getting it repaired in the workshop but they chose to go ahead. Anyway, I ordered and replaced the blown SMPS control IC (N501, 44608P40) and the 2.2kW 2W resistor (R504) that feeds it. Unfortunately, that didn’t fix it and I was faced with a new symptom – the set was now pulsating. I then replaced C517 (22mF) as it was the only small electro in the power supply but it made no difference. Next, I checked for shorts on all the secondary voltage rails, particularly the line output stage, but there were none. I even shorted the base and emitter terminals of the line output transistor (V302, 2SD1651) and hung a 60W globe off its collector but the set still kept hiccupping. siliconchip.com.au We seek an experienced Electronics Engineer who has graduated in the last 4 years and has been working in the field for 1 or more years. The role is to help develop exciting products for Laservision’s international markets. Above average skills in computers, software and electronics required. Contact Michelle Osmetti for an information kit: michelleos<at>laservision.com.au www.laservision.com.au June 2007  73 Serviceman’s Log – continued Frankly, I hadn’t expected this sort of trouble but I persevered. I figured that for the power supply to be pulsating, it must be looking into some sort of over-current or over-voltage situation. As a result, I decided to disconnect each supply rail in turn until it stopped hiccupping. Disconnecting the main B+ 110V and the 12V-2 rails made no difference, so I moved onto the 12V-1 line. And that was it – the hiccupping ceased as soon as this line was disconnected. The circuit design here is rather unusual, as the 12V-1 rail is derived via two diodes on two different secondary coils on the chopper transformer – ie, via diode VD511 from pins 12 & 11 and via VD509 from pin 10 which also feeds VD508 for the +110V rail. VD509 is in series with an SCR (V502) which is controlled by the power/standby pulse from the microprocessor (ie, this pulse drives the SCR’s gate) I checked all these components out of circuit and could find nothing wrong with any of them. I then found that by disconnecting the gate of the SCR, the set would come on with perfect sound and picture and with all the voltage rails correct. Puzzled by this, I discussed the problem with a support technician at Palsonic who was very helpful. He offered a few ideas and suggested that the problem might even be due to a faulty microprocessor. Resistor R518 (47kW) and capacitor C513 (180pF 2kV) are in parallel with 74  Silicon Chip VD509 and V502 so I took those out of circuit and checked them but both were OK. I refitted them and switched the set on with the gate of V502 connected. The set started to pulsate as before but then, after about a dozen such hiccups, it suddenly decided to work. Despite all my best endeavours, I now couldn’t get the set to stop working! I soak tested it for a week before returning it to the owner with a warning to call me if there was any further trouble. Shortly after that, I got a fax from Palsonic suggesting I should try fitting an extra 1mF 63V decoupling capacitor off the gate of the V502 SCR. Unfortunately, it was too late for that but if I get a recall, I will fit the extra part. In the meantime, I am letting sleeping dogs lie. Ripply Telefunken Telefunken is unfortunately no longer made in Germany but the one I had on my bench looked pretty well made nonetheless. It was a model TTV-29D and its fault was a huge ripple moving down either the left or right side of the picture, like a large wave. At first I thought it might be hum, so I started by checking the power supply rails and the electrolytic capacitors hanging off them. But all seemed to be OK so I downloaded a service manual off the web and checked all the voltages. By now, I was beginning to recognise this was probably an east-west correction fault but I couldn’t understand why it kept moving. Gradually I also realised that bright scenes (which equate to higher beam current) were also affecting it. The circuit shows the east-west circuit to be as simple as it gets. First, there’s an EEPROM where the main control adjustments are stored. Then there’s a large microprocessor and a jungle IC that then feeds through an output FET. This in turn is connected via a coil to the horizontal deflection yoke. I checked the FET and a few of the components around the deflection stage and then the proverbial penny dropped. What biases this output FET apart from the jungle IC? The answer is a 75kW resistor (R307) which is connected between its drain and gate terminals. I checked this resistor and found it to be open circuit. I didn’t have a 75kW resistor in stock so I fitted an 82kW resistor instead. That fixed the problem so well it didn’t need any further adjustments. A simple fix I have repaired many Panasonic M16 chassis TVs over the years, the majority being straightforward. However, I did strike a TC-29V26A with an unusual fault recently. The set was refusing to tune in Band III VHF stations but this is normally quite easy to diagnose and fix, as it is either the tuner or the band-switching IC. In this case, it was neither so I had a bit of a battle on my hands. Despite its age, this set was in beautiful order and was very clean inside. And because the board in question is mounted vertically, it meant that no liquid could fall and collect on the PC board to cause corrosion. Despite this, there was a “blackish” mark next to a couple of capacitors on the copper side of the PC board. When I scraped off the lacquer above this mark, I found that a copper track had gone open circuit. Soldering a link across this break fixed the fault. But what had actually caused the problem? Before you say that the electros nearby were obviously leaking, I can tell you that they definitely were not. I even took them out and measured them and both were perfectly OK. I replaced them anyway, just to be on SC the safe side. siliconchip.com.au Introducing the seven-a-side PICAXE FUN WITH THE NEW Picaxe PICAXE 14-M! by Stan Swan There’s a new kid on the block! He’s from the rapidly-growing PICAXE family (now with 11 siblings!) and goes by the name of 14-M. If you’re a PICAXE fan, Stan wants you to meet him ’cos he’s really friendly – especially if you already know his younger brother, 08-M! I t could come as a suprise to readers who were only aware of the ever popular baby 08(M), but the PIXAXE family now in fact has 11 members – titled by their number of IC legs (8,14,18,28,40). Revolution Education’s new PIXAXE 14-M, based around the well-thought-of MicroChip PIC16F684, is billed as an 08-M “big brother” but in fact looks best suited to simplify introductory work for students and hobbyists. The “M” refers to the musical capabilies of both PIXAXEs” – but don’t expect MP3 quality! The 14-M offers a lot more than the 08-M. Indeed, the 14-M may become the entry-level PIXAXE microcontroller, overtaking the 08-M in time. The pricing is attractive and its increased and more logically positioned I/O pins serve to make the 14M even easier to work with than the 08. Old PIXAXE hands may scoff at the thought of something that’s even easier than the 08 they’re used to and now know almost like the back of their hands. But it’s important to consider new learners and the fresh crop of PIXAXErs continually emerging – through magazine articles such as this and now, thankfully, a large number of schools and colleges who have introduced their students to electronics and micros through the mighty PIXAXE. This protoboard layout photo fairly closely matches the “3V” version (the left-hand layout overleaf). Stan has used multicolour LEDs in his version – you can do the same as long as you don’t try to use white or blue LEDs, because these often aren’t reliable on a 3V supply. siliconchip.com.au June 2007  75 It’s because the PIXAXE is so easy to understand and use that it has achieved such popularity. You may recall that when we first introduced SILICON CHIP readers to the PIXAXE (in a series of articles starting in February 2003), We commented at the time that the PIXAXE could become the “555” of the nineties simply because it was/is so simple yet so versatile. It’s opportune that such a PIXAXEas the 14-M has been developed, especially since the five inputs (including two ADC) and six outputs offer many educational applications normally beyond the limited I/O PIXAXE-08(M). Also, the “top” eight pins of the 14-M are pin-for-pin compatible with the eight-pinned 08-M, so all those breadboarded PIXAXE circuits can use exactly the same layout and much the same code. Who let the smoke out? A word of precautionary housekeeping: the 14-M’s DIP14 (Dual In-line Plastic 14-pin) packaging makes the chip a look-alike to numerous cheap logic ICs, so it is essential to clearly label them before turning them loose on beginners! It’s sometimes difficult to get across the concept that even though chips might look the same, they’re different. To some, a chip is a chip is a chip! Many young students (and even weary-eyed academics!) may innocently consider all such 14-pin ICs as interchangeable – the same problem periodically arises with DIP8-style PIXAXE-08s being mistaken for 555s and 741s, with frustrating (and occasionally explosive) outcomes. Initial 14-M circuits In pondering initial ‘icebreaker” educational circuitry that the 14-M suits, the in-line nature of the six outputs struck me as being particularly well suited for ever-popular LED chaser and level displays. Such circuits are simple to wire up but are most entrancing, while cheap and various-colour LEDs allow all manner of colourful effects to be explored. The looping algorithms required may also focus and stretch young minds, with the instant feedback provided to the validity of a program effect encouraging both V+ CON2 DB9 2 3 5 10k IN4 IN3 PROGRAM EDITOR (TO PC SERIAL PORT) K A IN2 IN1 K LEDS A IN0 PICAXE 14M 14 SC 2007 7 1 2 1 3 EQUIVALENT PICAXE 08M 12 FOOTPRINT 4 11 5 PICAXE 10 14M 6 9 7 13 OUT0 OUT1 OUT2 OUT3 OUT4 14 8 330Ω∗ λ 330Ω∗ λ 330Ω∗ λ 330Ω∗ λ 330Ω∗ λ 330Ω∗ λ 6x LEDS OUT5 * WITH RED, GREEN OR YELLOW LEDS SUPPLY CAN BE 3V AND 330 Ω RESISTORS CAN BE OMITTED new Picaxe 14m – led chaser Take one PIXAXE 14-M, six LEDs, two programming resistors . . . and you have yourself a chaser! We’ve superimposed the 08-M on the 14-M in the circuit to show how it is pin-for-pin compatible – at least that much is! the talented and lethargic. A teachers dream! As it’s apparent that the 14M can be considered at several levels – both introductory and advanced – “power” users may even be able to redefine some of the 14-M’s nominal inputs and outputs, potentially allowing up to nine outputs under “portc” commands. Normally even handling eight LEDs on such chasers requires a more involved and costly PIXAXE 18 (see www. picaxe.orcon.net.nz/18leds.jpg). Indeed, the first electronic chaser we ever saw (after the motor-driven mechanical monstrosities before the solidstate era) consisted of two 14-pin IC flip-flops connected as a twisted ring counter, along with a significant number of components to pulse them and to decode the output to drive lamps. And now you can do it with one PIXAXE and six LEDs! V+ 3V (2x “AA” ALKALINE) * PICAXE-14M 22kΩ 5 3 2 4.5V (3x “AA” ALKALINE) * 22kΩ PICAXE-14M 6 x 330Ω PROGRAMMING A 5 3 2 PROGRAMMING A 10kΩ K 0V 22k RXD +4.5V* IO CHANNELS PROGRAMMING RESISTORS 6 x LEDs 10kΩ K 0V 6 x LEDs * OR 4.8V (4x NiCd OR NiMH) On the left is the protoboard wiring for the chaser circuit with a 3V supply. We’ve shown rectangular LEDs because (as the photo shows) these can fit together better on the standard 0.1” protoboard spacing. With our more usual 4.5V (or 4.8V) supply the wiring is slightly more complicated, as shown at right, because series resistors need to be added to ensure the LEDs aren’t destroyed by too much current. But either way, you could hardly get a much simpler circuit! 76  Silicon Chip siliconchip.com.au Save Up To 60% On Electronic Components PICAXE 14-M BASIC LISTINGS – 14CHASE.BAS AND 14WIPER.BAS ‘14CHASE.BAS PICAXE 14M demo LED follow me chase April 2007 ‘Ensure latest editor used with 14M option selected ‘Uses 6 LEDs at output pins 0-5 for a ‘follow me’ L-R effect ‘b1=LED number chase: for b1=0 to 5 ‘starts follow me chase high b1:pause 100:low b1:pause 100:next b1 ‘sequentually wink LEDs wait 1 ‘1 second rest goto chase ‘repeat entire effect ‑‘14WIPER.BAS PICAXE 14M demo LED ‘wiper’ April 2007 ‘Ensure latest editor used & 14M option selected ‘Uses 6 LEDs at output pins 0-5 for accelerating L-R-L wiper action ‘b0=delay b1=LED number wiper: for b0=250 to 0 step -5 ‘decreasing chase delays(msecs) for b1=0 to 5 ‘loop for outward LED chase high b1:pause b0:low b1:pause b0:next b1 ‘briefly flash LED for b1=4 to 1 step -1 ‘loop for return LED chase high b1:pause b0:low b1:pause b0:next b1 ‘briefly flash return LED next b0 ‘decrease delay between flashes wait 1 ‘1 second rest goto wiper ‘repeat entire effect You can download from www.picaxe.orcon.net.nz/14chase.bas and www.picaxe.orcon.net.nz/14wiper.bas Construction Although purpose-designed PC boards are already available, the small breadboard layout we’ve used since we introduced PIXAXE circuits perfectly suits many 14-M designs, especially (as we mentioned earlier) 08-M/14-M program pins are identically placed. And this layout is so simple even a raw beginner shouldn’t run into any problems (just watch chip and LED polarities!) To further ease constructional woes, the 14-M can be run from two “AA” batteries (3V) thus removing the need for the usual 330W dropping resistors on the LEDs. A 50mm screw or nail can replace a cell in the popular PIXAXE 3 x AA (4.5V) battery box as a simple way to lower the supply voltage, or a less common 2 x AA switched box can be used. The reduced (3V) voltage will normally still program and run the PIXAXE with LEDs, although blue and white LEDs may no longer illuminate, as these more recent (and costly) LEDs normally need a supply higher than 3V. Of course, there’s nothing to stop you running the 14-M from the more usual 4.5V supply but in this case 330W current-limiting resistors will be required to ensure you don’t burn out the LEDs. Therefore we have shown these on the circuit diagram and one of the breadboard layouts. Also, it is possible that some serial ports may become unreliable at lower supply voltages, so a 4.5V supply is better from that point of view. But once you’ve programmed the 14-M and you wish to make your chaser “portable”, a SC 3V supply should be perfectly OK. Programs, references and labels: Hosted for download, along with other 14M material, at www.picaxe.orcon.net.nz/14m.htm siliconchip.com.au Great New ET-AVR Stamp Only $26.47 * Includes ATMega128 Microcontroller * Up to 53 I/O Points * 8-Channel 10-bit A/D * Direct In-Circuit Programming * Ideal as a Removable Controller Exciting New ET-ARM Stamp * Includes LPC2119 Microcontroller * High-Speed Operation * Heaps of I/O plus CAN, UART, I2C * In-Circuit Programming * Supporting Board Also Available Only $33.12 Save Heaps on Components Only $7.85 We carry a wide range of Integrated Circuits, Microcontrollers, Capacitors, LEDs and LCDs. All at very competitive prices. We are your one-stop shop for Microcontroller Boards, PCB Manufacture and Electronic Components. www.futurlec.com.au Radio, Television & Hobbies: ONLY the COMPLETE 00 $ 62 archive on DVD &P +$7 P • Every issue individually archived, by month and year • Complete with index for each year • A must-have for everyone interested in electronics This remarkable collection of PDFs covers every issue of R & H, as it was known from the beginning (April 1939 – price sixpence!) right through to the final edition of R, TV & H in March 1965, before it disappeared forever with the change of name to Electronics Australia. For the first time ever, complete and in one handy DVD, every article and every issue is covered. If you're an old timer (or even young timer!) into vintage radio, it doesn't get much more vintage than this. If you're a student of history, this archive gives an extraordinary insight into the amazing breakthroughs made in radio and electronics technology following the war years. And speaking of the war years, R & H had some of the best propaganda imaginable! Even if you're just an electronics dabbler, there's something here to interest you. NB: Requires a computer with DVD reader to view – will not work on a standard audio/video DVD player Use the handy order form on page 81 of this issue. June 2007  77 Even More PICAXE Developments . . . As well as the new PICAXE 14-M introduced over the past few pages, Revolution Education Ltd, the UK based developers of the PICAXE system, have been hard at work for the last few months. Clive Seager talks us through the latest PICAXE developments. PICAXE 14-M +V Serial in ADC 4 /input 4 Infrain/Input 3 Input 2 Input 1 ADC 0 / Input 0 PICAXE-28X1 1 14 2 13 3 12 4 11 5 10 6 9 7 8 0V Output 0 / Serial Out / Infraout Output 1 Output 2 Output 3 Output 4 Output 5 The new PICAXE-14M has been primarily designed for those 08M projects “when you need just one more input / output!”. The main difference is that the 14M has 11 i/o pins (5 inputs and 6 outputs), as opposed to the 08M’s 5 i/o pins. The pin-out of the new chip is shown in figure X, and those of you who like to use stripboard or breadboards to test out your projects will be pleased to see the very straight forward ‘inputs on left – outputs on right’ layout. V+ 08M 0V RXD OUT0 IN4 OUT1 IN3 OUT2 IN2 OUT3 IN1 OUT4 IN0 OUT5 14M Apart from the pin-count, the 14M is almost identical to the 08M, with the same memory capacity (approximately 80 lines of code) and music ring tone commands. The 08M and 14M are also pin compatible, so with care it is also possible to design a system that will support both parts. Reset ADC0 / In a0 / ULPWU ADC1 / In a1 ADC2 / In a2 ADC 3 /in a3 Serial In Serial Out 0V Resonator Resonator In0 / Out c0 / timer clk In1 / Out c1 / pwm1 In2 / Out c2 / pwm2 In3 / Out c3 / i2c scl / spi sck 1 28 2 27 3 26 4 25 5 24 6 23 7 22 8 21 9 20 10 19 11 18 12 17 13 16 14 15 Output 7 Output 6 Output 5 Output 4 Output 3 Output 2 Output 1 Output 0 +V 0V In 7 / Out c7 / ser rx kb data In 6 / Out c6 / ser tx / kb clk In 5 / Out c5 / spi sdo In 4 / Out c4 / i2c sda / spi sdi and features at an equivalent, or even lower, cost. Therefore Revolution have recently announced the launch of the PICAXE-28X1, which is based upon the new PIC16F866, and supersedes both the 28A and 28X. The 28X1 is pin and program compatible with previous versions, so to upgrade an existing design you can simply swap chips over. However the new 28X1 has a much larger memory capacity, which in turn means more features and support for a longer user program. In fact the 28X1 is a complete new ‘generation’ of PICAXE chip, in which the compilers and bootstrap firmware have been completely re-written. At the same time Revolution have tried to include all the commonly requested extra features from customers. 28X1 New Features Program / Data Memory PICAXE-28X1 The original PICAXE chip, the PICAXE-28A, was based upon one of the very first ‘self re-writeable’ PIC chips that Microchip produced, the PIC16F872. This was later followed by the enhanced PICAXE-28X, based upon the PIC16F873A. However, as microcontroller technologies have progressed, both these PICs have now been effectively superseded by a new generation of PIC chips, which have additional memory 78  Silicon Chip The 28X1 program memory capacity has been doubled to 4096 bytes. This equates to approximately 1000 lines of BASIC code. The data eeprom memory (for read/write commands) has also been doubled to 256 bytes. Variables The 28X1 directly accessible variables (b0, b1 etc.) have also been doubled to 28 bytes (14 words). However a completely new feature is the scratchpad, which is a new separate, additional 128 byte RAM area for rapid saving of siliconchip.com.au CON2 +4.5V* temporary variable data. A common example of use would DB9 IO PROGRAMMING RESISTORS CHANNELS 2 be in saving a long received serial data stream from a GPS module or for storing arrays. λ via the 330Ω∗ 3 scratchpad address can be directly Each accessed 1 2 13 OUT0 PUT and GET commands. However a more versatile use is 22k RXD EQUIVALENT λ 330Ω∗ PICAXE 10k(scratch pad pointer), via the5 ptr 3 08M 12 which is a unique virtual OUT1 FOOTPRINT ‘pointer variable’. IN4 λ 330Ω∗ 11 The pseudo variable4 name ‘<at>ptr’ can then be used in 6x IN3 OUT2 PROGRAM commands as if it was a PICAXE normal variable330Ω∗ but in λuse actuLEDS EDITOR 10 ally to the5 current address on the scratchpad (TO‘reads/writes’ PC 14M IN2 OUT3 SERIAL PORT) pointed to by ptr. Similarly if ‘<at>ptrinc’ is330Ω∗ used as aλ variable 9 6 in a command, read/write is to theOUT4 current pointer address IN1 λ to point 330Ω∗ K and then Kthe pointer (ptr) automatically increments 8 7 14 LEDS A A IN0 OUT5 to the next address. PICAXE Therefore ‘<at>ptrinc’ can be* WITH repetitively RED, GREEN ORused YELLOW in LEDS com14M SUPPLY CAN BE 3V AND 330 Ω 7 mands such as serin to save data in different scratchpad RESISTORS CAN BE OMITTED 14 addresses1 e.g. Hibernate / Sleep 2007 new Picaxe 14m – led chaser Reset ptr = 10 serin 1,N2400, <at>ptrinc, <at>ptrinc, <at>ptr The reset command will reset the chip, clearing variable values and restarting the program. In this example the three serial bytes received will be saved in scratchpad positions 10, 11 and 12 and can then be later accessed, for example, by GET commands. An additional 96 bytes of memory are available via the traditional peek/poke commands and so the 28X1 now has over 250 user byte variables. Setint Resonator a) Serial Communications SC The 28X1 can use either an internal (max. 8MHz) or external (max. 20MHz) resonator. The setfreq command is used to switch between frequencies (internal and external frequencies may be used within the same program). To reduce PCB costs/simplify circuits the resonator may be totally omitted if desired. If the external resonator fails, operation will automatically drop back to the 4MHz internal resonator. Some commands with specific timing (eg, readtemp or irout) always use the internal resonator, switching back to normal timing after the command completes. New Commands Table/Readtable A 256 byte data lookup table can now be defined when the program is written and automatically downloaded (as part of the program) into the 28X1. This is a very convenient and efficient way of storing data, eg, for storing LCD menu text, calibration values etc. The new hibernate command enters a permanent low power sleep state. The 28X1 can then only be woken by a hardware interrupt, eg, a hardware serial or i2c reception. Play / Tune The 28X1 supports the mobile phone ring tone play and tune commands (as 08M) on any output pin. Calibadc The ADC reading within PICAXE chips is based upon the supply voltage, which can sometimes vary over time (eg, as a battery runs down). The new calibadc command uses a fixed internal 0.6V source to provide a known voltage ADC reading. This enables users to calibrate their ADC readings to a known fixed voltage, regardless of battery state. The polled interrupt now also has the option to operate when a condition is NOT true, as well as the original ’match condition’ option. Enhanced Peripheral interfacing Serial communication can now be carried out in three different ways: 1) serin/serout act via the standard input/output pins as before. However the serin commands now support a timeout feature. 2) serrxd and sertxd act via the PICAXE download cable. This enables user program data to be both transmitted and received via the download pins of the 28X1. 3) hserin and hserout are a more advanced method of communication via the on-board serial hardware pins. This allows advanced features such as wake-up from sleep, background receive and much higher serial baud rates. The background receive allows serial data to be automatically saved into the scratchpad area as the PICAXE chip completes other tasks. b) I2C The 28X1 can now act as an I2C master or I2C slave. The new slave mode is fully automatic and is the rec- Pauseus 5V The additional pauseus command creates a smaller time delay than pause. Pauseus operates in 10us multiples. MASTER Timer Data – SDA The 28X1contains a general use 16 bit background timer/ counter. When in timer mode this timer runs in the background at a user defined frequency (eg every second). The timer variable can be read at any time. Timer overflow is used to set a flag bit (toflag). When in counter mode, the timer records the number of rising edge pulses on input 0. This occurs in the background, while the PICAXE program performs other tasks. siliconchip.com.au 5V 4.7k 4.7k Clock – SCL 0V 5V SLAVE 1 SCL 5V UP T0 120 SLAVES ARE SUPPORTED SLAVE 2 SCL SDA SDA 0V 0V 0V June 2007  79 ommended method of networking multiple PICAXE-28X1 chips. The slave features are completely automatic, so the PICAXE chip acting as a slave can still run a normal program, with the I2C slave read and writes occurring in the background without program intervention. The I2C interface operates in the same manner as the popular 24LCxx EEPROM chips, with the 128 scratchpad bytes as the read/write memory area. This method theoretically allows one 28X1 master to control over 120 28X1 slaves, all connected via a common two wire I2C bus. However the software has also been enhanced and now supports improved compilers for all PICAXE chips. The enhanced compilers support many new programming structures, such as ‘do…loop’, ’if…elseif…endif’ and ‘select case’ to simplify the process of writing PICAXE programs. To use these new structures simply make sure you have selected the ‘enhanced compiler’ from the View>Options>Editor menu. Simulation c) SPI (3 wire) The 28X1 supports 3-wire (SPI) communications on input/output pins or via the dedicated hardware pins (which provide a faster transfer rate). Normal input/output pin support is included to allow both i2c and SPI on the same system (as hardware SPI and hardware i2c use the same pins). d) Infrared The 28X1 supports infrared input (with timeout) and output. Sony SIRC format. e) One Wire The 28X1 fully supports the Dallas/Maxim 1-wire protocol, allowing direct control of all 1-wire parts. Enhanced Mathematical Capability The 28X1 has enhanced mathematical capabilities, such as support for brackets within mathematical statements: eg, let b4 = b1 + (b2*5) A number of new mathematical and trigonometric functions (sin, cos, sqr, <<, >> etc) are now supported, as well as new commands for converting number types (eg bintobcd, bintoascii etc.) Another new feature within the software is the ability to simulate, and single-step through BASIC program listings. This allows you to try out your BASIC programs before they are even downloaded to the PICAXE chip. During simulation, each line is highlighted as it is carried out and an on-screen graphic of the PICAXE chip enables inputs to be changed and the state of output pins to be studied. Naturally all variables can also be viewed as the program simulates. Summary Programming Editor Software The free PICAXE Programming Editor software has been updated to support the new 14M and 28X1 new parts. Please make sure you are now using version 5.1.0 or later – if you need to upgrade, a free patch is available on the www.picaxe.co.uk website. The new PICAXE-14M, PICAXE-28X1 (and the new 40 pin option, PICAXE-40X1) provide a range of enhanced features and/or pinout options compared with existing PICAXE parts. For further details please visit the PICAXE website at www.picaxe.co.uk SC Next month: We look at putting thePage 28X1 30/3/07 2:12 PM 1 to work, creating a PICAXE MP3 player. RF_SiliconChip_60x181mm.qxd Enhanced Compiler ELECTRO CHEMICALS Chemical Technology 80  Silicon Chip • Dust Off • Freezing Spray • Electronic Cleaning Solvent No. 1 • Electronic Circuit Board Cleaner • Electrical Contact Cleaner Lubricant • Video Head Cleaner • Ultrasonic Bath Cleaner • Isopropyl Alcohol • Protek • Contact Treatment Grease • Contact Treatment Oil • Solvent Diluted Oil • Contact Cleaning Strip • Circuit Board Lacquer • Q43 – Silicon Grease Compound • Heat Sink Compound Contact us to find your nearest distributor: sales<at>rfoot.com.au Tel: 02 9979 8311 Fax: 02 9979 8098 Richard Foot Pty Ltd, 14/2 Apollo Street,Warriewood NSW 2102 siliconchip.com.au siliconchip.com.au June 2007  81 Frequency Switch By John Clarke & Julian Edgar A cheap, adjustable design that lets you switch devices on and off according to speed. Main Features • Adjustable switching level be- tween 10Hz and 500Hz input • Dual double-pole changeover 5A relay contacts • Switches on rising or falling frequency • Adjustable hysteresis • Easy to build T HERE ARE MANY automotive performance applications where you want to turn something on or off on the basis of road or engine speed. A shift light is a good example – you want a high intensity LED to illuminate just before the red-line, to warn you that it’s time to snatch the next gear. Or maybe you want a variablelength intake manifold to change from long to short runners at non-standard revs. Or perhaps you want to operate a device on the basis of road speed – eg, switch on an intercooler fan when the car is moving only slowly or sound an over-speed warning when you’re going too fast, for example. This Frequency Switch can do all of those things – and more. It also has adjustable hysteresis (that’s the difference between the switch-on and switch-off frequencies) and comes with both a LED and a relay. The relay is there so that you can switch big loads, while the LED can be mounted on the dash so that you can see the switch operation. Alternatively, the LED could be used purely as an indicator – eg, as an over-speed warning or as a shift light. Construction The Frequency Switch can be used to trigger a shift light – an indication that engine revs are getting close to the red-line and it’s time to change up a gear. 82  Silicon Chip The Frequency Switch is a simple kit to build but you should make one decision before you start work. Will you be using it to detect a frequency that is rising to the trip point or falling to the trip point? The unit can be configured to work with either type of signal but if you know which way you’re going, you won’t have to make changes later on. The detection of a rising frequency will be the more common application – for example, triggering a shift-light when engine revs reach a high speed. However, if you want something switched as frequency decreases to a certain level – for example turning on an intercooler fan when the car is siliconchip.com.au How It Works The frequency input signal is applied to a 10kΩ resistor and then to zener diode ZD1 which limits the signal to between +16V and -0.6V. The 10nF capacitor filters the signal, removing high-frequency noise. The signal is then applied to pin 1 of IC1 via another 10kΩ limiting resistor. IC1 is a frequency-to-voltage converter. The pin 1 input signal is compared with the voltage at pin 11 which is set at about +1.8V using 10kΩ and 3.3kΩ voltage divider resistors across the 7.4V supply. A comparator within IC1 will provide an output signal if the signal level at pin 1 swings above the 1.8V threshold for pin 11. This internal comparator drives a frequency-to-voltage converter which charges the capacitor at pin 2 and then transfers this charge to the capacitor at pin 4. Trimpot VR1 adjusts the voltage de- travelling slowly – then you’d configure the Frequency Switch to detect a falling frequency. So what are the changes made for the differing configurations? They’re simple: for a rising frequency (low to high) detection, link LK1 is placed in the (L/H) position (that is, closest to the top of the PC board when the board is orientated as shown in Fig.1). For siliconchip.com.au veloped at pin 3 with respect to the input frequency. This voltage is monitored by another internal comparator which has its inputs at pins 4 and 10. Pin 10 monitors the voltage set by trimpot VR2 (Threshold). The output at pin 8 will be high (+7.4V) when pin 4 is below pin 10. If pin 4 goes above pin 10, pin 8 will go low (0V). Hysteresis is included by virtue of the series 100Ω resistor, trimpot VR3 and diode D3. Hysteresis prevents the output from oscillating when the signal is just at the threshold point. The pin 8 output from IC1 drives transistors Q1 and Q2. Either one of these transistors can be selected to drive the relay, depending on the setting of link LK1. When LK1 is in the H/L position, Q1 drives the relay and when LK1 is in the L/H position, Q2 drives the relay. This enables the relay to switch when the input changes from a high-frequency signal to a low- detection of a falling frequency (high to low), link LK1 is moved to the H/L position. Note that the Frequency Switch in the photos is configured to switch on a falling frequency (H/L), while the parts overlay diagram (Fig.1) shows the PC board configured to switch on a rising frequency (L/H). When assembling the PC board, frequency signal (LK1 in position H/L), or when the input changes from a low frequency to a high frequency (LK1 in position L/H). LED1 lights whenever the relay is energised. Power Supply Power 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 for regulator REG1. All the circuitry is powered from REG1 via D2, except for the relay and LED1 which are driven from the +12V supply. D2 is included to reduce the 8V from the regulator to about 7.4V which is necessary for correct operation of IC1 (it prevents an internal power supply zener diode in IC1 from conducting). Suggested Uses • Operate a shift-light at set revs • Operate changeover inlet manifolds • Operate an intercooler fan at low road speeds • Over-speed warning • Control active spoilers • Auto trans over-drive lock-out June 2007  83 Where To Buy A Kit This design was originally published in SILICON CHIP’s “Performance Electronics For Cars”. A kit of parts is available from Jaycar Electronics. “Performance Electronics For Cars” is available from Silicon Chip Publications and from Jaycar. Fig.1: use this diagram and the photos of the completed project when assembling the PC board. Take particular care with the components that are polarised – for example, the diodes, IC and electrolytic capacitors. The Frequency Switch is a multi-purpose building block that can be used to operate a shift light, alter intake manifold runner length, turn on intercooler fans at low road speeds – and a host of other uses. Both LED and relay outputs are provided. Resistor Colour Codes Value 4-Band Code (1%) 5-Band Code (1%) 100kΩ 10kΩ 3.3kΩ 1.8kΩ 1kΩ 100Ω 10Ω brown black yellow brown brown black orange brown orange orange red brown brown grey red brown brown black red brown brown black brown brown brown black black brown brown black black orange brown brown black black red brown orange orange black brown brown brown grey black brown brown brown black black brown brown brown black black black brown brown black black gold brown make sure that you insert the polarised components the correct way around. The diodes, IC, LED, transistors, voltage regulator and electrolytic capacitors are the easiest to make mistakes with. During construction look at the 84  Silicon Chip photos and overlay diagram closely to avoid making mistakes. Set-Up & Fitting The Frequency Switch can be set to two broad frequency ranges: 10-100Hz or 50-500Hz. If measuring engine RPM, this corresponds to 600-6000 RPM for the first range or 300-30,000 RPM for the second range. To set the required range, connect +12V and ground and then measure the voltage between TP1 and ground. Adjust VR2 for 1.5V if you want the first frequency range or to 6V if you want the second range. In most applications, the first (ie, lower) range will be required. That done, you can install the unit in the car. In addition to providing power (switched +12V ignition supply) and earth connections, you will need to tap into the frequency signal that you want to monitor and connect this signal to the input terminal. This signal wire can be from the: • Road speed sensor • ECU tacho output • Switching side of an injector • Crankshaft or camshaft position output sensor At this stage, don’t connect anything to the relay – you will be able to see when the relay clicks over as the LED will light (and in quiet environments you’ll also hear the relay change over). So how do you set the trip point? You might want to have the Frequency Switch trigger a shift-light at 6000 RPM. But you don’t have to start off holding the engine at six grand – instead, adjust VR1 until the LED comes on at (say) 3000 RPM and then goes off as revs again drop. By adjusting the hysteresis pot (VR3), you should be able to alter how much the engine speed drops before the LED turns off. (Hint: if the LED flashes on and off around the switch-off point, increase the hysteresis by turning VR3 anticlockwise.) With the system working as it should, turn trimpot VR1 a little more anti-clockwise to increase the trippoint frequency and then blip the engine until it again switches on the siliconchip.com.au Parts List Fig.3: the on-board relay can be used to switch large loads. For example, as shown here, a high-power shift light could be wired into place. 1 PC board coded 05car051, 105 x 60mm 1 plastic case, 130 x 68 x 42mm (optional – not in kit) 5 PC-mount 2-way screw terminals with 5mm pin spacing 1 12V PC mount DPDT 5A relay (Relay1) 1 3-way header with 2.54mm spacing 1 jumper shunt with 2.54mm spacing 1 1MΩ horizontal trimpot (VR1) 1 2kΩ multi-turn top adjust trimpot (VR2) 1 10kΩ horizontal trimpot (VR3) Semiconductors 1 LM2917 frequency-to-voltage converter (IC1) 1 7808 3-terminal regulator (REG1) 2 BC337 NPN transistors (Q1,Q2) 1 5mm red LED (LED1) 2 16V 1W zener diodes (ZD1,ZD2) 3 1N4004 1A diodes (D1,D2,D4) 1 1N4148 switching diode (D3) On modified engines with changeover intake manifolds, the frequency switch can be used to set the revs at which the runners swap from long to short length. LED. By making changes to VR1 and then assessing the results with blips of the throttle, you should be able to quickly and easily set the trip point at the correct engine revs. Note that VR1 is a multi-turn pot. This has been used so that the trip point can be adjusted very precisely – however, if you’re not used to this type of pot, be aware that you can keep on turning it endlessly and never reach a clear “stop”! In the above example, you’ll probably want only a small hysteresis (ie, a small difference between the switchon and switch-off frequencies). But in some cases, a much larger hysteresis works very well. For example, if you use the Frequency Switch to turn on an intercooler siliconchip.com.au fan at low road speeds, the adjustable hysteresis can be used to keep the fan running until you’re again travelling fast enough to push air through the core. In this case, you could set the turn-on at 10km/h and then adjust the hysteresis so the fan doesn’t turn off until 35km/h. This works well in practice where heat-soak of the intercooler is more likely to have been occurring after you’ve been stopped for awhile and are driving off slowly. The device that is to be triggered by the relay will normally be switched via the Normally Open (NO) and Common (C) relay contacts. Fig.3 shows these connections. Note that because a double-pole, double-throw (DPDT) relay has been used, another completely in- Capacitors 2 100µF 16V PC electrolytic 2 10µF 16V PC electrolytic 1 1µF 16V PC electrolytic 1 22nF MKT polyester (code 223 or 22n) 1 10nF MKT polyester (code 103 or 10n) Resistors (0.25W, 1%) 1 100kΩ 2 1kΩ 7 10kΩ 1 100Ω 1 3.3kΩ 1 10Ω 1 1.8kΩ dependent circuit can also be switched simultaneously. This other circuit can even turn off the second device as the first is switched on. Note that if you just want to simply monitor a frequency (eg, engine revs), you can delete the relay and just mount the LED on the dashboard instead. In most applications, once the Frequency Switch is set, it won’t need to be altered again. The PC board fits straight into a 130 x 68 x 42mm jiffy box, so when the system is working correctly, it can be tucked SC out of sight. June 2007  85 A flying visit to CeBIT 2007 With technology – and in particular IT – changing at a near-impossible-to-keep-up-with rate, we try to keep up-to-date by visiting shows such as CeBIT. After last year’s CeBIT, which we visited but didn’t report on (we rated it pretty much a dead loss), we were a little reluctant to take the time out for CeBIT 2007. And while there was plenty of “more of the same but different”, CeBIT 2007 did have enough to make the visit worthwhile. Of course, the exhibits are only one part of CeBIT – there are also virtually continuous seminars held either in any of several “open” venues within the exhibition or in the adjacent, purpose-build auditorium. While some of these looked more than interesting and would, no doubt, have provided valuable insights for those involved in those areas, time simply did not permit us more than a cursory glance at any of the seminars. A few individual products and services stood out and we hope to review by Ross Tester some of these later (assuming exhibitor co-operation!). That’s one of the negatives we’ve found about shows such as CeBIT: plenty of hoop-la and promises from those on the stand but very little (often no) follow-up in the days and weeks after. These people pay a lot of money to exhibit but then waste the opportunities that present themselves. Enough of the negatives, what did You might have to look closely but those are working mobile phones the girls are holding in the water (fitted with SKINS). And yes, they still work perfectly. Phones? They’re near the bottom of the picture . . . 86  Silicon Chip siliconchip.com.au PocketSurfer 2 is the fastest cellular-based web browser around and comes complete with 20 hours per month on-line time with no extra charges. we find at CeBIT 2007 (of course, this is just a small selection). • A pocket-sized internet surfer. No, it’s not a PDA, nor a phone, nor anything else. All it does is allow completely mobile internet access. So what’s so great about that? Serious surfing of the internet on PDAs and phones is a joke – you’d only do it if you had to. The screens are too small to read unless you enlarge to the point where you’re forever chasing parts of the page across the screen. And for the most part, access is slow and relatively expensive. Of course, you can use your notebook computer but who wants to lug around even a lightweight notebook just to get internet access? The PocketSurfer2 doesn’t try to be anything but a fast, cheap internet access device for those away from their desktop. It’s large enough to give a full-width screen with easily-read characters. But it’s tiny – at just 155 x 75 x 15mm and 174g. It’s fast, too; five to seven seconds per page and that’s coming in over the Vodafone cellular network. Most importantly, it’s cheap: the retail price of $399 includes 12 months of air-time (up to 20 hours per month) and there are no call charges, activation fees or air-time service charges. If you want up to 50 hours per month that’s $7.99 per month or unlimited siliconchip.com.au usage will cost you just $14.99 per month. More information: www. pocketsurfer.com.au • Speaking of the internet, we think we have at last found a way to make money from it – not by trying to sell stuff but by sharing your unused broadband capacity with the world – and they pay for it! Tomizone offers a free-to-join, freeto-maintain system where you add wireless to your broadband, turning it into a hotspot. They charge users a low rate ($4 per day or $20 per week) and give you half! Most people under-use their broadband capacity so it looks like it could be a winner. You could get your broadband paid for by others! It’s a system we plan on investigating more fully in a future issue of SILICON CHIP. www.tomizone.com • A condom for your mobile? OK, that’s not how they are being marketed but that’s what they look like! The idea is to completely waterproof your phone just in case the worst happens. (And according to a mate in the mobile phone repair business, that’s the vast majority of phone “service”, whether by washing the jeans with the phone in the pocket or taking an unexpected swim with your phone . . .). They’re actually called Mobile Skins and they roll on to the phone just like, well, a condom. When fitted properly, the phone can be totally immersed. You could take it swimming or surfing! What’s more, it’s also protected against mud, paint, beer, moisture, dust . . . in fact, just about anything that could play havoc with your phone. It’s not just consumers who would benefit from Skins – trades people/ construction, sportsmen and women, boaties and so on. They’re very low priced and are very east to fit – and the phone retains total functionality. At CeBIT, they had a spa set up with models to demonstrate the fact that the phones could go under water. At least I think I saw a phone. More info? www.skins-mobile.com Soanar’s General Manager Neil Walker (shown here with Jaycar’s Gary Johnston) was very happy with the response he received from CeBIT visitors. June 2007  87 • Face and eye recognition. There were several organisations showing their wares in these areas, mainly for security applications – from building down to PC. But one which really did catch our eyes (pardon the pun) was the “Dikablis” eye tracking system from Germany (part of the large international contingent exhibiting at CeBIT 2007). Originally developed by the Technische Universitat Munchen to “fine tune” their own documentation and computer screens, this system is now being sold to the world. In a nutshell, this hardware/software system is designed to track eye movement as a person reads – either a computer screen (web page, for example) or printed material. The software then analyses the movement to show how the information is being interpreted. A medium which allows smooth, efficient eye movement is much more effective than one which forces the eyes to jump all over the place. The same system has been used to evaluate car dashboards, for example, to see how efficient they can be made to keep the eyes off the road for the minimum amount of time. Exhibited by Ergoneers GMBH (ie, ergonomic engineers), you’ll find more at www.ergoneers.com (especially if you can speak German!). • Still on a security theme, Adel Australia had a number of fingerprintrecognition doorlocks. You may recall we featured a fingerprint lock in SILICON CHIP in January 2007; now Adel has introduced all-in-one models where Walletflash MP3 (right) is said to be the world’s thinnest MP3 player – it’s the same size as a credit card. Above is the company’s WalletFlash cards. the fingerprint reader is actually built into the lock. • Credit-card size MP3 players and flash memory. They’re the slimmest in the world. Called “WalletMP3” and “Walletflash” and literally credit card size (90 x 55mm and perhaps 2mm thick) these are about to hit the market in Australia (planned for July). Because the MP3 player is small enough to go in your wallet, you don’t need to carry yet another device. They’re also waterproof, very tough (they’ve been put through a lot of tests including being baked in an oven!) and can store up to about 400 songs in their 2GB memory. They have the usual MP3 player controls on the card and the headphones plug in to the same USB adaptor used to load up the player. The Walletflash is the same size, so now you can store your important backups (they come in capacities up to 2GB) with no risk of loss (unless you lose your wallet!). www.walletflash. com.au • From the world’s slimmest to the world’s largest! Panasonic displayed If you were looking for hardware, software, peripherals, add-ons or any other bits and pieces, there was a stand at CeBIT to satisfy you. Some specialised, others had bits of everything. This photo shows a typical example. Many exhibitors offered “show specials” – some of which were actually special! 88  Silicon Chip their 103-inch Plasma High Definition TV, along with a new range of tough notebooks (and a lot of other goodies!). • GN had the 24-carat gold and stainless steel Bluetooth headsets for mobile phones from Jabra (Bluetooth really appeared to have taken off this year. WiFi was of course there but it appeared to be significantly down over last year. VoIP was also highly visible with quite a number of exhibitors, as was GPS/mapping software). • Soanar Electronics – we also caught up with General Manager Neil Walker and Managing Director Gary Johnston. Soanar, who specialise in component distribution, embedded processor boards, displays and touch screens told us that they were very happy with the response from CeBIT visitors and the business generated by their stand. • Agilent Technologies had their range of test equipment for neworking, wireless and RF. • Google was there, selling, demonstrating, promoting . . . ummm . . . Google, I guess. And if you wanted entertainment, you could get that too with several stands showing interactive games with exceptional graphics. Then there was the football field. Yes, a real, live, football field to play on, with an overhead projector marking out the field. No, boss, I didn’t get a game . . . SC siliconchip.com.au Simple Panel Meter – Revisited I n the March 2007 issue we published a simple digital voltmeter and ammeter. Since then, prompted by several readers’ emails, phone calls and letters, we have revisited this project and found that there have been some errors and oversights. First of all, in the text we stated that they were wired for 20V DC full scale out of the box. This is not correct: they are wired for 200mV DC full scale. This came about because the meters we used had already been configured for 20V – and you know what they say about assumptions! So to use the Oatley DPM you need to set the voltmeter to 20V. As per the instructions which come with it, there are three pairs of terminals + + IN VOLTAGE MEASUREMENT (20V) LETTERS REFER TO PC BOARD C TERMINATIONS E + + SHUNT (0.0125 Ω) A CURRENT MEASUREMENT (20A) 12.34 – IN 10k B + IN 15k D F – IN IFT1 1 100nF ON 1.234 + 4 5 3 100nF SHUNT: 0.0125  250mm HEATING WIRE (0.05 /m) Q1 BC548 B 9V 2 A 1N4148 A E SC 2007 REVISED CIRCUIT 100nF 5 4 1 1 5 2 3 4 SIMPLE AMMETER & VOLTMETER IF TRANSFORMER (BASE UP) 1N4148 K + BC548 A ZENER C B E D C LINK A-C 1k 13V ZENER 4 3 1nF AMMETER DPM (UNDERNEATH) + 100nF 2 C E 15k 1N4148 K 15k POWER K A IFT2 F B OUTPUT – + POWER + – LINK B-D VOLTMETER DPM SHORT P2 FOR P3 20V P2 FSD P1 9V BATTERY POWER SWITCH CURRENT MEASUREMENT siliconchip.com.au VOLTAGE MEASUREMENT on the left edge of the PC board (looking at the back of the board with the trimpot to the top). These are labelled (with very tiny print!) 1,2,3 from the bottom up and referred to as P1, P2 and P3 on the instruction sheet. As supplied (for 200mV), P1 is shorted by solder – for 20V operation, this short is removed and P2 is shorted instead. The second problem is a little more serious and can only be blamed on a brain explosion. We went to all the trouble of arranging an isolated supply for the ammeter, then connected the voltmeter to this same supply. Therefore the meters could not be used in to measure the same circuit, as intended. As that other Mr Simpson would say, “doh!” Fortunately, the fix is very simple: the correct way to run only the ammeter from the add-on PC board isolated supply while the voltmeter is directly from the 9V battery, as per the revised diagram. That way the two meters can be used to measure different parts of the same circuit, as intended. Finally, there should be links connected between points A and C and between points B and D on the isolated supply board to connect the shunt wiring across the trimmer capacitor. While the circuit diagram was correct, the original wiring diagram does not have these links shown and the photograph shows them in the wrong position. SC June 2007  89 Vintage Radio By RODNEY CHAMPNESS, VK3UG DC-to-AC Inverters From The Valve Era There have always been odd little offshoots from the mainstream technology of radio and DC-to-AC inverters are one such offshoot. This month, we’ll take a look at two of those early inverter circuits and describe their restoration. D URING THE VALVE era, many radio manufacturers also made DC-to-AC inverters to power items such as electric shavers, TV sets and other 240VAC items from 6, 12 or 32V DC. However, with the exception of radiograms, 240VAC radios were rarely powered from inverters, as the inverters were not very efficient. 90  Silicon Chip Getting some of those early inverters working again can be quite a challenge. So let’s take a look at a couple of the more common units. Bland’s shaver inverter Bland Radio Ltd of Adelaide were well-known for their Operatic series of good performance radios. They also made various other devices, one of which was an electric shaver inverter. This ran off 6V DC and produced 240V AC with a near square-wave output waveform. Its current drain was approximately 4A for a power output of up to 15W. My unit was obtained when a friend decided to reduce his radio collection. When I subsequently pulled the cover off the unit to see what was inside I found an Oak V5211 vibrator, an ironcored transformer and a 0.5mF 600V buffer capacitor. These buffer capacitors can be unreliable so I immediately replaced it with a new polyester type with a slightly higher voltage rating than the original unit. There being nothing else to check, I then attached the inverter to a 6V power supply and absolutely nothing happened. Further examination of the device then revealed that the inverter had to have a shaver or some other similar device connected to it to work. Basically, the earth pin on the appliance’s 240V plug is used as the switch to turn the device on – see Fig.1. As shown, the earth terminal on the inverter’s 240V socket was modified so that it had two separate sections. Plugging in the appliance connected these two sections (via the earth pin on the plug), thus allowing the inverter to operate from the 6V supply. In practice, this means that the inverter will not operate until a 3-pin plug is inserted. It then turns off automatically when you remove the plug. It’s quite a neat scheme but I wonder how many men complained that the unit didn’t work, not knowing that their shaver needed to have a 3-pin plug and not a 2-pin plug! No voltage Having solved that problem, the visiliconchip.com.au brator started but I still couldn’t get any voltage out of the unit. An ohmmeter soon showed that the transformer was still OK so that left the vibrator itself, although it appeared to be working. When the vibrator was removed from its case it initially appeared to be OK. However, the ohmmeter showed that all the contacts except for the reed drive had oxidised. So although they were making physical contact with each other, there was no conductivity across the contacts. This is not a common problem but I’ve seen it before and the solution is quite simple. It’s just a matter of cleaning the contacts using some very fine wet and dry paper. The procedure is as follows. First, tear off a small amount of wet and dry paper about 20mm square. That done, fold it in half with the abrasive side out and insert the paper between each set of points. Finally, press the points lightly together and rub the paper back and forth between the points until they are clean. In practice, several pieces of paper are usually needed to get the points thoroughly clean and conducting again. In this case, once cleaning had been completed, an output voltage of over 400V peak-to-peak was obtained with no load. I then put a 5.6kW wirewound resistor across the output and briefly obtained an output of about 260V before the unit suddenly stopped. For such a simple device, it was certainly causing more than its fair share of trouble. I checked the circuit around the vibrator and the voltages around it were normal. I then re-checked the points and this time found that the reed drive had fouled up. As a result, the points were all given a further clean-up, after which the unit worked well. I then checked the waveform on the oscilloscope and found what was nominally a square wave but with some slight resemblance to a sinewave. There was no significant overshoot on the waveform. I don’t have a true RMS meter to measure the output but according to the oscilloscope, it appeared to be producing roughly 240V AC. Having got the unit working, I decided to trace out the circuit and it turned out to be a little different to most vibrator circuits. In this unit, the synchronous split-reed V5211 vibrator is wired so that the whole siliconchip.com.au This simple 6V DC to 24VAC inverter was made by Bland Radio Ltd of Adelaide and was designed to power electric shavers. Fig.1: the Bland Radio inverter circuit. Its mains socket used a 2-piece earth terminal which functioned as a switch for the 6V DC input (a scheme that would now be illegal). This meant that the mains plug fitted to the appliance had to have an earth pin in order for the inverter to work. primary winding is used but the current through the winding is reversed at the end of each half cycle. Many vibrator inverters did not work well on inductive loads and shavers usually are inductive. How­ ever, there was no sign of excessive pitting on the vibrator contacts so it would appear that it did a satisfactory job, despite the nature of the devices likely to have been connected to it. In fact, Bland Radio’s vibrator power supplies were well designed and rarely required vibrator replacement. Van Ruyten model VR58TV Up until the late 1950s and even into the 1960s, 240V mains power was still not available to some farms and other remote areas. Instead, they mostly relied on 32V DC power plants for lighting but only some household equipment was designed to operate from this supply voltage. June 2007  91 There’s not much inside the Bland Radio inverter’s case – just a standard Oak vibrator unit, a transformer, a capacitor and the mains socket. Items like washing machines, electric irons, food mixers and vacuum cleaners were available but 32V refrigerators were not (kerosene refrigerators were used instead). A 32V 2-bar radiator was just not practical (an open fire or a kerosene heater were used instead) and the pleasure of watching TV was largely denied to these rural citizens as early TV sets were only designed for 240V mains operation and used upwards of 200W of power. Now 200W of power consumption was not in itself too much for a 32V system but the fact that people like to watch TV for many hours per day meant that the battery bank would have been flattened quite quickly. In addition, the cost of home generated power was about a dollar per kilowatt hour or more, which is a lot more than we now pay for electricity. Converting 32V DC to 240V AC is inherently inefficient and when the efficiency is taken into account, the total power consumption climbs to nearly 300W. This photo shows the Van Ruyten power vibrator (top) alongside a standard Oak vibrator. During that era, the only manufacturer to produce DC-powered TV sets was Ferris. These purpose-built set incorporated their own vibrator supply and were more efficient than mains sets operating from an inverter. However, despite the inefficiency and the cost, there was still some demand for inverters to run mains-operated TV receivers. One well-known DC-AC inverter manufacturer was Liebmann Clarke Pty Ltd of Richmond in Victoria. The company manufactured several different models, designed to power 240V AC equipment from 6V, 12V or 32V DC. Their highest power unit was the Van Ruyten model VR58TV. This 32Vto-240V inverter had an output power of 200W and weighed in at 10kg. It was specifically designed to power black and white TV sets from a 32V bank of batteries on a farm or station. In fact, it would appear that the model number indicates the design year and that its prime purpose was to power TV sets. Cleaning up When I obtained the inverter, it looked pretty shabby, with rust showing through the paint work, the voltage adjustment knob missing and the front panel hanging loose. Unfortunately, I didn’t have any knobs that exactly matched the type used so I used one that suited the era. On the other hand, the inside of the inverter was quite clean and only a quick clean-up with a small paint brush was required. That done, I separated the unit from its case and removed the front panel. The case and its panel were then washed with soapy water and left to dry. Once they had dried, I set about removing the rust and old paint from these items using an angle grinder. The two parts were then sprayed with grey hammertone paint and the unit now looks almost like new. It’s certainly vastly better than the rusty unit it was before restoration. Overhauling the electronics It was now time to overhaul the works and my first step was to replace the 0.56mF 600V paper capacitor (C11) which was leaky as expected. This was swapped out for two 0.27mF 630V polyester capacitors wired in parallel. All the other capacitors were being run 92  Silicon Chip siliconchip.com.au well under their voltage ratings so I left them in circuit. That proved to be a mistake but more of that later. The vibrators in these inverters often had a hard life due to the uncertainty of whether the load would be inductive or capacitive. C5-C8 and C11 are the buffer capacitors which “tune” the inductances so that the circuit resonates to around 50Hz. However, with capacitive or inductive loads, this tuning will be altered, leading to sparking at the vibrator points. I don’t have any spare 32V vibrators so I dismantled the unit that was in the inverter. This was done by desoldering the two solder joints between the base and the can and then sliding the vibrator out. A close inspection of the points showed that one pair out of the five sets had a “dag” on one contact which mated with a hole in the other point. This was fixed by releasing the adjustment screw and filing the dag away. I then cleaned all the points with fine wet and dry paper. That done, I re-installed the adjustment screw and rotated it until I had the same gap as the other parallel set of points. A feeler gauge was then used to make the adjustment as accurate as possible. I then connected the vibrator to a 12V supply to check that the reed drive worked properly. This is the above-chassis view of the Van Ruyten VR58TV DC-AC inverter. Note the two large transformers that are used in conjunction with the power vibrator at the rear. This checked OK and required only a minor adjustment. Re-assembly The next step was to re-assemble the inverter. First, the 32V power leads and the grommet were fed through the hole at the bottom of the panel, then the switch was mounted in position, followed by the 240V output socket. The 32V switch was next on the list and this proved to be difficult, as the screws are hard to get at. Eventually, I got them in but then found that the switch wouldn’t work – much to my frustration. On inspection, it appeared to be fouling on the switch cut out on the Fig.2: this is the redrawn circuit for the Van Ruyten 32V DC to 240VAC inverter. The vibrator drives the two sections of the two transformer primary windings in a series push-pull arrangement, while the secondaries are connected in series to drive the output socket. siliconchip.com.au June 2007  93 This under-chassis view of the Van Ruyten inverter shows it to be a more complicated beast than the low-power Bland Radio unit. The red arrow points to the four new polyester capacitors that were fitted. front panel. Fortunately, the previous owner had left all the screws, nuts and bolts for the inverter in a plastic bag. Much to my delight, there were also two ceramic spacers in the bag and it appeared they had been used as spacers for the switch. Getting the nut onto the screw nearest the top of the chassis (furthest into the chassis) was no easy task. Eventually, I resorted to an old trick. The nut was pressed into the end of a plastic tube, after which I was eventually able to position it inside the chassis correctly to take the screw. The one towards the bottom of the chassis is much easier but I now know why the previous owner passed the unit on to This is the Van Ruyten inverter’s case before restoration. The rust was removed using a drill fitted with a wire brush, after which the unit was repainted so that it now looks almost like new. 94  Silicon Chip me – he couldn’t get it back together! The knob I selected for the High/ Low switch had a white recessed indicator line down the pointer section. However, this had largely disappeared so I scraped out the old paint using a scriber and cleaned it thoroughly. I then used “White Out” to fill the groove in the knob. Once this was dry, the excess was scraped off the knob using a razor blade, leaving a neat white line down the channel in the pointer. It now looks like new. It was now only a matter of sliding the chassis back into the case and fitting four screws. In addition, the rubber feet had long since disappeared from the bottom of the case so I used four large rubber stick-on furnituretype buffers to stand the case proud of the bench. These can be obtained from hardware or “$2” shops. The finished unit now looks quite attractive, especially when compared to the grubby unit it was before restoration. Testing Now it was time to test the unit. I slipped it out of the case, connected my 32V DC power supply to it and consiliconchip.com.au nected a 15W 240V lamp to the output as a load. This load was deliberately kept small as my 32V supply is only rated at 1.5A. At this stage, I still had the cover off the vibrator. I turned the power on and the unit started up and produced an output. Everything appeared to be OK, so I left it running on soak test. Unfortunately, it didn’t stay that way for long – the next time I came back, there were tiny bits of silver paper and other tiny bits of powdery material like confetti near the inverter. The inverter was still running quite happily so I turned it off to investigate. When I looked under the chassis, I was greeted by two capacitors that had blown their insides out. The two capacitors involved were among the primary circuit buffers (C5C8). They had overheated so badly that foil had been blown out of them. The inverter had kept going despite this catastrophic failure and none of the foil shorted anything out. It was easily fixed – the “confetti” was cleaned out and the four capacitors (which were still quite hot) removed from the chassis. These original paper capacitors were then replaced with a batch of four polyester type capacitors. As shown in one of the photos, the replacement capacitors were glued together with contact adhesive and then tied to the tag strip on the bottom of one of the transformers using a plastic cable tie. Photo Gallery: Astor Mickey Model DL MANUFACTURED BY RADIO CORPORATION, MELBOURNE in 1947, the “DL” was another model carrying the “Mickey” name. It was fitted with a full-width (almost) glass dial, with the loudspeaker mounted at the side of the cabinet. This set did not employ the reflex circuit that was later to become popular with “Mickey” models until the end of the series. Brown and cream were probably the most common cabinet colours and this mottled yellow example is unusual. The valve line-up was as follows: 6A8-G frequency changer, 6B8-G reflexed IF amplifier/1st audio amplifier/detector/AVC rectifier, 6V6-GT audio output and 5Y3-GT rectifier. Photo: Historical Radio Society of Australia, Inc. Why did they fail? The original paper capacitors are rated at 300V working, so why did they “blow up” when only 32V was being applied across them? The answer is that the actual voltage across them is in fact considerably higher than the supply voltage, as the circuit is roughly resonant at 50Hz. As a result, considerable voltage is developed across the total inductance of the primary windings as they are completely charged and discharged 100 times a second. I hadn’t checked for leakage across these capacitors as I had reasoned (erroneously) that even if they did have some leakage, it would not be serious enough to cause much heating. How wrong I was. The two that hadn’t blown up showed very low insulation resistance, so how low was the resistance in the two that did blew up? siliconchip.com.au In hindsight, I should have tested these capacitors for leakage resistance before starting the unit up and then I should have periodically (every few minutes) checked for any signs of overheating. Summary These vibrator-powered DC-to-AC inverters served the needs of the public quite well before the arrival of solid-state devices. A number of other brands were also produced although they were not as common as the Van Ruyten. Van Ruyten also produced a 100W version of the unit described above and it used just one transformer. The radio frequency (RF) filtering in the Van Ruyten unit may be sufficient so as not to noticeably impair domestic radio reception but the Bland Radio unit has no such RF filtering. As a result, the reception on any radio used with the Bland Radio unit would have been severely marred by interference due to sparking at the vibrator points. Based on my experience, these vibrator-type inverters were only moderately reliable due to the uncertain characteristics of the loads that they drove. By contrast, the Davey rotary motor alternator was a very reliable device which produced sinewave 240V AC, compared to the roughly square-wave output from the vibrator inverters. They also were not affected to any extent by the type of load that was connected to them. However, the Davey units were rarely seen as they were even more expensive than the vibrator inverters and drew even more current from the 32V SC DC power supply. June 2007  95 ASK SILICON CHIP Got a technical problem? Can’t understand a piece of jargon or some technical principle? Drop us a line and we’ll answer your question. Write to: Ask Silicon Chip, PO Box 139, Collaroy Beach, NSW 2097 or send an email to silchip<at>siliconchip.com.au Query on adjustable voltage regulators I was interested in a comment in the February 2007 article on the Remote Volume Control & Preamplifier Module. It states: “We’ve used adjustable regulators in this design because the ADJ terminals can be bypassed to ground to improve ripple rejection”. Don’t these bypass capacitors just restore the ripple rejection back to the same levels that the standard 78XX regulators have? The NSC datasheets seem to indicate that either circuit will have around -80dB ripple rejection at 100Hz. Is this just a misconception that is being perpetuated (I’ve seen the same thing done in other designs) or is there a real performance reason to prefer adjustable regulators over fixed? Also, could you further explain “two reverse-connected diodes (D7 & D10) across the output prevent their respective rails from being driven to the opposite polarity (eg, if a regulator fails)”? Did you mean “rectifier”? (S. J., via email). • You are quite right about the ripple rejection figure. Once the 10mF bypass capacitors are installed, the ripple rating of the adjustable regulators is essentially the same as the fixed output devices. Our text wrongly implies that we used the LM317 & LM337 adjustable regulators purely for the ability to decouple the ADJ pin. We neglected to mention that the adjustable devices have a tenfold performance benefit (according to National Semiconductor) over the fixed devices in line and load performance. They also feature improved overload protection. Additionally, we envisioned that these supplies would be useful in a variety of projects, hence the benefit of adjustable outputs. Regarding the reverse-connected diodes, it is indeed possible for one rail to be driven to the opposite polarity due to a failure in the powered device (not in the regulators, as stated). In this case, the diodes protect the regulators by clamping their outputs to one diode drop below (or above) ground. Capacitors for valve preamplifier I am currently replacing the capacitors in the valve preamp for hifi use (SILICON CHIP, February 2004) but I don’t seem to be able to find a 680nF 630V capacitor from either Jaycar or Altronics. Would a 470nF 630V unit be OK to use instead? (R. C., Doncaster, Vic). • It would be OK to use a 470nF 630V capacitor instead of the specified 680nF. The only difference would be a slight reduction in the far-bass response which probably will not be noticeable. If this does worry you, you could connect a 220nF 630V capacitor in parallel with the 470nF unit, to give a total of 690nF. Killing that sound blast from TV commercials Have you ever published a circuit to limit the surge in sound when TV programs go to commercials? If not, do you have any suggestions? (S. K., via email • A number of schemes have been devised over the years to combat the rise in audio level when adverts are on. One commercial system sensed the video “fade to black” at the start and end of commercials to turn off the audio but the TV networks have seen around that. We don’t know of any more effective method than killing the sound with your remote control or using a PVR to do time-shift. Transformer for 110V iron Some time ago while in Canada I bought a 110V iron to use for ski Porsche Takes Off In Second Gear I am the happy (almost) owner of a 1985 928 Porsche. This vehicle is fitted with a Mercedes Benz 4-speed auto transmission and it is normal for this transmission to take off from rest in second gear (a strange Teutonic quirk). The only way to make it take off in 1st gear is to mash your foot to the firewall. This closes the kick down switch and powers up a solenoid. Unfortunately, this results in much protestation from the rear tyres. In the interests of fuel consump96  Silicon Chip tion and driveability, I would like it to take off in 1st gear. I have fitted a manual switch in parallel across the kick-down switch but this has become tiresome in traffic. I want to have the kick-down switch automatically close after the car comes to a complete stop and to open after the car has moved away but with the opening point (speed) variable according to the throttle opening. Is there a kit or some other way I can achieve this? The vehicle is standard with an electronic speedo and fuel injection so picking up a road speed pulse and variable voltage from the throttle position sensor would not be a problem. The auto transmission is a fully hydraulic unit apart from the electric kick down system. (R. A., via email). • You could use the Frequency Switch this month on page 82. Use it to close a relay at the stopped (or almost stopped setting) for the kick down and release the relay at a higher speed, as set by the hysteresis setting. siliconchip.com.au Hesitation In High-Energy Ignition I built one of your High Energy Ignition systems, as featured in the December 2005 & January 2006 issues. It has been installed in a 1996 6-cylinder Falcon. I built the engine management version but rather than take a signal from the distributor output before any conditioning by the vehicle’s management system, I chose to take the signal from the coil primary connection, so that any timing changes made by the ECU will still have the same effect but will also be processed through the High-Energy Ignition. I fitted the 100W pull-up resistor as per the points version of the ignition and the vehicle runs very well. The benefit is immediately noticeable. However, at the initial moment the accelerator pedal is waxing. The iron is about 1kW and a transformer that would be suitable would be quite expensive. Have you ever published a project which would allow such a high-powered appliance to safely operate from 240VAC? (I. L., via email). • While an electronic circuit such as a zero voltage switching power controller (see our Heat Controller from the July 1998 issue) could reduce the RMS voltage from 240V to 110V to suit your iron, it would not be a safe option as 240VAC would still be applied to the heating element and it may not be designed to take that voltage stress. The only alternative approach is to use an auto-transformer or a fully isolating step-down transformer. Both will be relatively expensive. They are available from Harbuch Electronics in Hornsby (Sydney). Phone (02) 9476 5854. Moving coil RIAA preamplifier You recently published a moving coil variant of your Magnetic Cartridge Preamplifier in the Circuit Notebook pages (March 2007 issue). I would like to build this but what is its gain? Is there enough gain, say +62dB, to raise the output of my Ortofon cartridge (with an output of 200mV) siliconchip.com.au pressed, there is a split-second hesitation – the motor stutters then away it goes. Other than this moment of indecision, the motor runs wonderfully. I was wondering if the value of the pull-up resistor is causing my problem. The coil’s primary resistance is around 0.5W so the car’s management is not seeing the normal load. Do you think this might be the reason I am seeing the hesitation or could you suggest an alternative approach? Also, if I were to fit a resistor of around 0.5W in place of the 100W unit, would the current drain have any impact on the High-Energy Ignition itself? (G. M., Endeavour Hills, Vic). • A 100W resistor in place of the coil should be fine. You may need to line level, say 250mV? (T. R. Woodend, Vic). • The gain for the moving coil RIAA preamplifier shown in Circuit Notebook in March 2007 is +55dB (x 560) at 1kHz. Gain for the second stage is up to x11 or +20.8dB, so a 200mV signal can be boosted to 1.2V with VR1 set at maximum. The minimum setting for VR1 would provide 112mV output for a 200mV input. Therefore the gain should more than enough for your Ortofon cartridge. Remote switching with the SMS controller I recently built the SMS Controller which was published in SILICON CHIP in 2004. I also built several Remote Relay Switches, published in May 2006. I intend to use the controller to switch lights as well as other appliances on and off on a property on the Gold Coast. I have tested the Remote Relay Switch with the SMS controller for short periods of time and it works quite well. I propose to connect three Relay Switches to the controller. The Relay Switches may have to be energised for extended periods of time (several days). Do you see any problems with excessive loads on the switching integrated to slightly increase the dwell period so that the coil is ready to fire with sudden demands such as acceleration at low RPM. This should stop the hesitation. What we think is happening is that at idle the dwell period for the coil is correct, as the engine is running at a relatively constant RPM. But as soon as you put your foot down on the throttle, the engine load changes and the firing point (or timing) is changed. This change can reduce the dwell period momentarily as the microcontroller readjusts its calculations. As far as the microcontroller is concerned, the engine has had a sudden RPM change. This loss in dwell can prevent the coil from delivering its spark and so the engine hesitates. circuit? I have soldered it directly to the PC board. Or would you advise me to use the relay switch published in the November 2006 issue instead? (C. N., via email). • The Remote Relay Switch from the May 2006 issue would be a good choice. It uses a relay with a 200-ohm coil, so up to eight units could be driven from the SMS controller outputs without any problems, particularly as you’ve soldered the ULN2803 chip directly to the PC board. The DC Relay Switch described in the November 2006 issue is not suitable, as it cannot be used to switch 240VAC. Can Radar Speed Gun measure cricket balls? My three grandsons, being extremely keen cricketers, want me to build the recent Radar Speed Gun described in the November 2006 issue. Could you proffer an opinion if it could be used by their cricket club trainer to measure their bowling speed? (D. C., Bribie Island, Qld). • The Radar Speed Gun could probably be used to measure the speed of cricket balls but you may need to spray the balls with metallic paint, so they will reflect enough of the microwave radiation to give a reading. June 2007  97 Making The Active Crossover A 2-Way System I was most interested in the article “An Active 3-Way Crossover For Loudspeaker Systems” which was published in the January 2003 issue of SILICON CHIP. I subsequently purchased the kit from Jaycar and it sat around for a year or two before I began work on the project. Although I had initially planned for a 3-way system, I’ve since settled on a 2-way loudspeaker system and am therefore keen to know whether it would be easy to modify the kit or bypass part of the circuitry to allow the crossover to be used on a 2-way system. (L. D., Perth, W.A.). • A 2-way crossover can be implemented if you omit the bandpass Controlling audio level when burning CDs I burn LPs onto CD using my hifi record player and using the output signal from the headphone jack. This works well. However I cannot keep the volume the same between copies as my hifi volume control is by pushbutton and not by potentiometer. Can I use the kit in the March 2007 issue, called the Universal Infrared Remote Volume Control & Preamp, to do the job? I would like to choose my volume and see exactly how high or low the headphone output is. (T. Z., via email). • The Universal Infrared Remote Volume Control & Preamp is not suitable, in part because it does not display its input signal amplitude. There are a filter and just use the low-pass and high-pass filters. The crossover frequency would then be set to the same value for both the low and high-pass filters. The low-pass filter is for the woofer and the high-pass filter is for the tweeter. The unused bandpass filter circuitry includes op amps IC3c, IC3b, IC5d & IC5c in the left channel and op amps IC4c, IC4b, IC6d & IC6cd in the right channel. We recommend that you install the components for these op amps (use the default value 47nF capacitors and the 10kW and 20kW resistors) to prevent them from oscillating. number of ways to address this problem. If you’re happy with the quality of the recordings that you’ve made thus far, then it may be possible to retrofit a volume control potentiometer and VU meter to your record player. An easier method would be to monitor and control the signal level using Windows-based recording software. Additionally, you can make use of the special LP noise filters built into many of these packages. Check out our feature on transferring LPs to CDs in the September 2006 issue for details. Power supply for Mighty Midget amplifier I have built the Mighty Midget amplifier (SILICON CHIP, March 2002) and need some advice. Instead of lugging the family car battery with me, what sort of power supply would I require? (B. W., Toukley, NSW). • Given that the Mighty Midget can deliver up to 70 watts on peaks, the supply would need to deliver about 14V at 10A, which is a very big supply. The alternative is to use the same power supply arrangement as we used in the PortaPAL PA system featured in the February and March 2003 issues. In essence, this used a 12V SLA battery with a float charger. Electronic bell circuit wanted I am looking for an electronic bell circuit. The one I have in mind is similar to the types used in school amplifiers for end-of-period, etc. I have hunted the “web” without finding anything remotely suitable. Has SILICON CHIP ever done such a project? (R. J., Kangaroo Flat, Vic). • We published a DingDong doorbell project in the May 1992 issue. Fuel Mixture Display shows overload I purchased a Fuel Mixture Display from Jaycar. I have put the kit together and have one problem that I cannot figure out. I cannot set the span. It always goes to OL. Can you provide some guidance? (B. A., Oregon, Illinois, USA). • Check that you are getting -2.49V across REF1. VR1, VR2 & VR3 are different values and must be placed in the positions shown. VR1 should have a 504 code, VR2, a 254 code and VR3 a 203 code. 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. 98  Silicon Chip siliconchip.com.au The span problem could be because the offset is not set or VR2 is the incorrect value. Make sure the other resistors on the PC board are the correct values, in particular the 180kW & 100kW values associated with IC2a. NiMh battery charger I recently purchased the Cordless Power Charger Control Kit (SILICON CHIP, December 2006) with a mind to adapting it to charge 10 AA 2400mAh NiMH batteries connected in series. This raises a number of questions. First, what voltage and current ratings would I require on my plugpack to recharge the 10 cells, assuming, say, a 5-hour charge time? Second, what additional circuitry would I need to ensure that the current going to the cells is limited. I gather from the article that most power tool battery packs contain a current-limiting resistor. This being the case, could I simply introduce a current limiting resistor in series with the 10 AA cells to be charged? If so, how would I go about calculating the required value for this resistor? (L. S., via email). • The charge rate for a 5-hour charge for the 2.4Ah battery would be 670mA. So you would need a 1A DC plugpack at 15V or 18V. For 15V you would need a 3.9W 5W resistor. For an 18V plugpack use an 8.2W 10W resistor. The value may require some adjustment because the charge depends on the actual plugpack voltage and the voltage that the battery SC reaches during charge. Notes & Errata iPOD/MP3 Charger, February 2006: Some changes to the USB output are required to effectively charge the latest iPOD NANO 2nd generation (anodised aluminium case released September 2006) and the 5th Generation iPOD video. For the iPOD NANO 2nd generation, the D- USB pin (pin 2) must connect to a 2.5V source while the D+ USB pin (pin 3) must connect to a 2V source. These voltages can be provided using resistors connected across the 5V USB supply pins (pins 1 & 4), as shown in Fig.1 . For the iPOD NANO 1st generation and 5th generation video (5G), the connection to the D- pin should be at 3.3V while the D+ pin should connect to 0V, as shown in Fig.2. In most cases, the circuit shown in Fig.2 will also work for the iPOD NANO 2nd generation player. Note that all resistors are 0.25W. This information supersedes that published in March 2006. Digital Stereo VU/Peak Meter, May 2007: transistors Q1 & Q2 on the overlay diagram of Fig.5 are incorrectly labelled. The transistor closest to IC4 should be Q2 (BC327) while the lower transistor should be Q1 (BC337). The circuit diagram on pages 66-67 (Fig.3) is correct. Also, on page 72, third column, second paragraph, the text should read “to the left of transistor Q1” (ie, Q2 should be Q1). Jacobs Ladder, April 2007: production versions of this kit have revealed a tendency for the specified BU941P TO-218 transistor to overheat. The solution is to fit the transistor with a TO-220 heatsink such as Jaycar Cat HH-8504 and to change the 0.47W 5W resistor to 1W 5W. This resistor should be spaced off the PC board by about 4-5mm to improve its heat dissipation. LOOKING FOR A SEA COUNTRY CHANGE? See the stars again! Breathe the Fresh Air! Don’t miss this once-in-a-lifetime opportunity! Now offered for sale is the historic former Eudunda School built in 1878. Located on an elevated corner double block of 1.25 acres on the extreme eastern crest of the Mt Lofty ranges, at Eudunda, 105km NE of Adelaide between the Clare and Barossa Valley wine areas. The original teacher's stone home has a large double bedroom, second bedroom, office and lounge. An extension with modern kitchen, laundry and bathroom was added in 1975, with later upgrades, including extensive air conditioning. A separate, self-contained, air-conditioned granny flat, built in 2000, has two bedrooms, (master with ensuite), large lounge, kitchen, and dining area. The old school, attached to the original teacher's home has three huge adaptable stone rooms: the original is 10x6.15m; the second, added in 1883 is 6.1m square. The third (1917), 7.4x7.25m, still has lab benches and cupboards. A separate 12x6m metal-clad building with washroom and toilet was added in 1985, while a 10.3x6.2m steel shed, with concrete base and storage shelving, is able to hold several vehicles. It has three-phase power and broadband internet. An almost unobstructed view from east to west, the land sloping down to the Murray Basin, gives a radio horizon covering a vast area into Victoria and NSW. The whole property has been well maintained. The present owners, since 1972, have had very little impact on the original fabric. Address: 22 Ward St, Eudunda, SA 5374 Google Earth coordinates: 34°10' 25.04" S, 139°05'16.66"E Price: $550,000 The perfect home and/or work location for: iRadio Amateurs iAstronomers iProgrammers iSoftware Developers iService Techs iEngineers iAny home business iTelecommuters iHobbyists iExperimenters iAnyone who wants to escape the rat race! For more information, phone the owner on (08) 8581 1484. siliconchip.com.au June 2007  99 ALL S ILICON C HIP SUBSCRIBERS – PRINT, OR BOTH – AUTOMATICALLY QUALIFY FOR A REFERENCE $ave 10%ONLINE DISCOUNT ON ALL BOOK OR PARTSHOP PURCHASES. CHIP BOOKSHOP 10% (Does not apply to subscriptions) SILICON For the latest titles and information, please refer to our website books page: www.siliconchip.com.au/Shop/Books PIC MICROCONTROLLERS: know it all SELF ON AUDIO Multiple authors $85.00 The best of subjects Newnes authors have written over the past few years, combined in a one-stop maxi reference. Covers introduction to PICs and their programming in Assembly, PICBASIC, MBASIC & C. 900+ pages. PROGRAMMING and CUSTOMIZING THE PICAXE By David Lincoln (2nd Ed, 2011) $65.00* A great aid when wrestling with applications for the PICAXE See series of microcontrollers, at beginner, intermediate and Review April advanced levels. Every electronics class, school and library should have a copy, along with anyone who works with PICAXEs. 300 pages in paperback. 2011 PIC IN PRACTICE by D W Smith. 2nd Edition - published 2006 $60.00* Based on popular short courses on the PIC, for professionals, students and teachers. Can be used at a variety of levels. An ideal introduction to the world of microcontrollers. 255 pages in paperback. PIC MICROCONTROLLER – your personal introductory course By John Morton 3rd edition 2005. $60.00* A unique and practical guide to getting up and running with the PIC. It assumes no knowledge of microcontrollers – ideal introduction for students, teachers, technicians and electronics enthusiasts. Revised 3rd edition focuses entirely on re-programmable flash PICs such as 16F54, 16F84 12F508 and 12F675. 226 pages in paperback. by Douglas Self 2nd Edition 2006 $69.00* A collection of 35 classic magazine articles offering a dependable methodology for designing audio power amplifiers to improve performance at every point without significantly increasing cost. Includes compressors/limiters, hybrid bipolar/FET amps, electronic switching and more. 467 pages in paperback. SMALL SIGNAL AUDIO DESIGN By Douglas Self – First Edition 2010 $95.00* The latest from the Guru of audio. Explains audio concepts in easy-to-understand language with plenty of examples and reasoning. Inspiration for audio designers, superb background for audio enthusiasts and especially where it comes to component peculiarities and limitations. Expensive? Yes. Value for money? YES! Highly recommended. 558 pages in paperback. AUDIO POWER AMPLIFIER DESIGN HANDBOOK by Douglas Self – 5th Edition 2009 $85.00* "The Bible" on audio power amplifiers. Many revisions and updates to the previous edition and now has an extra three chapters covering Class XD, Power Amp Input Systems and Input Processing and Auxiliarly Subsystems. Not cheap and not a book for the beginner but if you want the best reference on Audio Power Amps, you want this one! 463 pages in paperback. DVD PLAYERS AND DRIVES by K.F. Ibrahim. Published 2003. $71.00* OP AMPS FOR EVERYONE By Bruce Carter – 4th Edition 2013 $83.00* This is the bible for anyone designing op amp circuits and you don't have to be an engineer to get the most out of it. It is written in simple language but gives lots of in-depth info, bridging the gap between the theoretical and the practical. 281 pages, A guide to DVD technology and applications, with particular focus on design issues and pitfalls, maintenance and repair. Ideal for engineers, technicians, students of consumer electronics and sales and installation staff. 319 pages in paperback. by Sanjaya Maniktala, Published April 2012. $83.00 Thoroughly revised! The most comprehensive study available of theoretical and practical aspects of controlling and measuring EMI in switching power supplies. Subtitled Exploring the PIC32, a Microchip insider tells all on this powerful PIC! Focuses on examples and exercises that show how to solve common, real-world design problems quickly. Includes handy checklists. FREE CD-ROM includes source code in C, the Microchip C30 compiler, and MPLAB SIM. 400 pages paperback. By Garry Cratt – Latest (7th) Edition 2008 $49.00 Written in Australia, for Australian conditions by one of Australia's foremost satellite TV experts. If there is anything you wanted to know about setting up a satellite TV system, (including what you can't do!) it's sure to be covered in this 176-page paperback book. See Review Feb 2004 SWITCHING POWER SUPPLIES A-Z PROGRAMMING 32-bit MICROCONTROLLERS IN C By Luci di Jasio (2008) $79.00* PRACTICAL GUIDE TO SATELLITE TV See Review March 2010 ELECTRIC MOTORS AND DRIVES By Austin Hughes & Bill Drury - 4th edition 2013 $59.00* This is a very easy to read book with very little mathematics or formulas. It covers the basics of all the main motor types, DC permanent magnet and wound field, AC induction and steppers and gives a very good description of how speed control circuits work with these motors. Soft covers, 444 pages. NEWNES GUIDE TO TV & VIDEO TECHNOLOGY By KF Ibrahim 4th Edition (Published 2007) $49.00 It's back! Provides a full and comprehensive coverage of video and television technology including HDTV and DVD. Starts with fundamentals so is ideal for students but covers in-depth technologies such as Blu-ray, DLP, Digital TV, etc so is also perfect for engineers. 600+ pages in paperback. RF CIRCUIT DESIGN by Chris Bowick, Second Edition, 2008. $63.00* The classic RF circuit design book. RF circuit design is now more important that ever in the wireless world. In most of the wireless devices that we use there is an RF component – this book tells how to design and integrate in a very practical fashion. 244 pages in paperback. PRACTICAL RF HANDBOOK AC MACHINES By Jim Lowe Published 2006 $66.00* Applicable to Australian trades-level courses including NE10 AC Machines, NE12 Synchronous Machines and the AC part of NE30 Electric Motor Control and Protection. Covering polyphase induction motors, singlephase motors, synchronous machines and polyphase motor starting. 160 pages in paperback. PRACTICAL VARIABLE SPEED DRIVES & POWER ELECTRONICS Se e by Malcolm Barnes. 1st Ed, Feb 2003. $73.00* Review An essential reference for engineers and anyone who wishes to design or use variable speed drives for induction motors. 286 pages in soft cover. Feb 2003 BUILD YOUR OWN ELECTRIC MOTORCYCLE by Carl Vogel. Published 2009. $40.00* by Ian Hickman. 4th edition 2007 $61.00* Alternative fuel expert Carl Vogel gives you a hands-on guide with A guide to RF design for engineers, technicians, students and enthusiasts. the latest technical information and easy-to-follow instructions Covers key topics in RF: analog design principles, transmission lines, for building a two-wheeled electric vehicle – from a streamlined couplers, transformers, amplifiers, oscillators, modulation, transmitters and scooter to a full-sized motorcycle. 384 pages in soft cover. receivers, propagation and antennas. 279 pages in paperback. *NOTE: ALL PRICES ARE PLUS P&P – AUSTRALIA ONLY: $10.00 per order; NZ – $AU12.00 PER BOOK; REST OF WORLD $AU18.00 PER BOOK To Place Your Order: INTERNET (24/7) PAYPAL (24/7) eMAIL (24/7) www.siliconchip. com.au/Shop/Books Use your PayPal account silicon<at>siliconchip.com.au silicon<at>siliconchip.com.au with order & credit card details FAX (24/7) MAIL (24/7) Your order and card details to Your order to PO Box 139 Collaroy NSW 2097 (02) 9939 2648 with all details PHONE – (9-5, Mon-Fri) Call (02) 9939 3295 with with order & credit card details You can also order and pay for books by cheque/money order (Mail Only). Make cheques payable to Silicon Chip Publications. ALL TITLES SUBJECT TO AVAILABILITY. PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. ALL PRICES INCLUDE GST ALL S ILICON C HIP SUBSCRIBERS – PRINT, OR BOTH – AUTOMATICALLY QUALIFY FOR A REFERENCE $ave 10%ONLINE DISCOUNT ON ALL BOOK OR PARTSHOP PURCHASES. CHIP BOOKSHOP 10% (Does not apply to subscriptions) SILICON For the latest titles and information, please refer to our website books page: www.siliconchip.com.au/Shop/Books PIC MICROCONTROLLERS: know it all SELF ON AUDIO Multiple authors $85.00 The best of subjects Newnes authors have written over the past few years, combined in a one-stop maxi reference. Covers introduction to PICs and their programming in Assembly, PICBASIC, MBASIC & C. 900+ pages. PROGRAMMING and CUSTOMIZING THE PICAXE By David Lincoln (2nd Ed, 2011) $65.00* A great aid when wrestling with applications for the PICAXE See series of microcontrollers, at beginner, intermediate and Review April advanced levels. Every electronics class, school and library should have a copy, along with anyone who works with PICAXEs. 300 pages in paperback. 2011 PIC IN PRACTICE by D W Smith. 2nd Edition - published 2006 $60.00* Based on popular short courses on the PIC, for professionals, students and teachers. Can be used at a variety of levels. An ideal introduction to the world of microcontrollers. 255 pages in paperback. PIC MICROCONTROLLER – your personal introductory course By John Morton 3rd edition 2005. $60.00* A unique and practical guide to getting up and running with the PIC. It assumes no knowledge of microcontrollers – ideal introduction for students, teachers, technicians and electronics enthusiasts. Revised 3rd edition focuses entirely on re-programmable flash PICs such as 16F54, 16F84 12F508 and 12F675. 226 pages in paperback. by Douglas Self 2nd Edition 2006 $69.00* A collection of 35 classic magazine articles offering a dependable methodology for designing audio power amplifiers to improve performance at every point without significantly increasing cost. Includes compressors/limiters, hybrid bipolar/FET amps, electronic switching and more. 467 pages in paperback. SMALL SIGNAL AUDIO DESIGN By Douglas Self – First Edition 2010 $95.00* The latest from the Guru of audio. Explains audio concepts in easy-to-understand language with plenty of examples and reasoning. Inspiration for audio designers, superb background for audio enthusiasts and especially where it comes to component peculiarities and limitations. Expensive? Yes. Value for money? YES! Highly recommended. 558 pages in paperback. AUDIO POWER AMPLIFIER DESIGN HANDBOOK by Douglas Self – 5th Edition 2009 $85.00* "The Bible" on audio power amplifiers. Many revisions and updates to the previous edition and now has an extra three chapters covering Class XD, Power Amp Input Systems and Input Processing and Auxiliarly Subsystems. Not cheap and not a book for the beginner but if you want the best reference on Audio Power Amps, you want this one! 463 pages in paperback. DVD PLAYERS AND DRIVES by K.F. Ibrahim. Published 2003. $71.00* OP AMPS FOR EVERYONE By Bruce Carter – 4th Edition 2013 $83.00* This is the bible for anyone designing op amp circuits and you don't have to be an engineer to get the most out of it. It is written in simple language but gives lots of in-depth info, bridging the gap between the theoretical and the practical. 281 pages, A guide to DVD technology and applications, with particular focus on design issues and pitfalls, maintenance and repair. Ideal for engineers, technicians, students of consumer electronics and sales and installation staff. 319 pages in paperback. by Sanjaya Maniktala, Published April 2012. $83.00 Thoroughly revised! The most comprehensive study available of theoretical and practical aspects of controlling and measuring EMI in switching power supplies. Subtitled Exploring the PIC32, a Microchip insider tells all on this powerful PIC! Focuses on examples and exercises that show how to solve common, real-world design problems quickly. Includes handy checklists. FREE CD-ROM includes source code in C, the Microchip C30 compiler, and MPLAB SIM. 400 pages paperback. By Garry Cratt – Latest (7th) Edition 2008 $49.00 Written in Australia, for Australian conditions by one of Australia's foremost satellite TV experts. If there is anything you wanted to know about setting up a satellite TV system, (including what you can't do!) it's sure to be covered in this 176-page paperback book. See Review Feb 2004 SWITCHING POWER SUPPLIES A-Z PROGRAMMING 32-bit MICROCONTROLLERS IN C By Luci di Jasio (2008) $79.00* PRACTICAL GUIDE TO SATELLITE TV See Review March 2010 ELECTRIC MOTORS AND DRIVES By Austin Hughes & Bill Drury - 4th edition 2013 $59.00* This is a very easy to read book with very little mathematics or formulas. It covers the basics of all the main motor types, DC permanent magnet and wound field, AC induction and steppers and gives a very good description of how speed control circuits work with these motors. Soft covers, 444 pages. NEWNES GUIDE TO TV & VIDEO TECHNOLOGY By KF Ibrahim 4th Edition (Published 2007) $49.00 It's back! Provides a full and comprehensive coverage of video and television technology including HDTV and DVD. Starts with fundamentals so is ideal for students but covers in-depth technologies such as Blu-ray, DLP, Digital TV, etc so is also perfect for engineers. 600+ pages in paperback. RF CIRCUIT DESIGN by Chris Bowick, Second Edition, 2008. $63.00* The classic RF circuit design book. RF circuit design is now more important that ever in the wireless world. In most of the wireless devices that we use there is an RF component – this book tells how to design and integrate in a very practical fashion. 244 pages in paperback. PRACTICAL RF HANDBOOK AC MACHINES By Jim Lowe Published 2006 $66.00* Applicable to Australian trades-level courses including NE10 AC Machines, NE12 Synchronous Machines and the AC part of NE30 Electric Motor Control and Protection. Covering polyphase induction motors, singlephase motors, synchronous machines and polyphase motor starting. 160 pages in paperback. PRACTICAL VARIABLE SPEED DRIVES & POWER ELECTRONICS Se e by Malcolm Barnes. 1st Ed, Feb 2003. $73.00* Review An essential reference for engineers and anyone who wishes to design or use variable speed drives for induction motors. 286 pages in soft cover. Feb 2003 BUILD YOUR OWN ELECTRIC MOTORCYCLE by Carl Vogel. Published 2009. $40.00* by Ian Hickman. 4th edition 2007 $61.00* Alternative fuel expert Carl Vogel gives you a hands-on guide with A guide to RF design for engineers, technicians, students and enthusiasts. the latest technical information and easy-to-follow instructions Covers key topics in RF: analog design principles, transmission lines, for building a two-wheeled electric vehicle – from a streamlined couplers, transformers, amplifiers, oscillators, modulation, transmitters and scooter to a full-sized motorcycle. 384 pages in soft cover. receivers, propagation and antennas. 279 pages in paperback. *NOTE: ALL PRICES ARE PLUS P&P – AUSTRALIA ONLY: $10.00 per order; NZ – $AU12.00 PER BOOK; REST OF WORLD $AU18.00 PER BOOK To Place Your Order: INTERNET (24/7) PAYPAL (24/7) eMAIL (24/7) www.siliconchip. com.au/Shop/Books Use your PayPal account silicon<at>siliconchip.com.au silicon<at>siliconchip.com.au with order & credit card details FAX (24/7) MAIL (24/7) Your order and card details to Your order to PO Box 139 Collaroy NSW 2097 (02) 9939 2648 with all details PHONE – (9-5, Mon-Fri) Call (02) 9939 3295 with with order & credit card details You can also order and pay for books by cheque/money order (Mail Only). Make cheques payable to Silicon Chip Publications. ALL TITLES SUBJECT TO AVAILABILITY. PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. ALL PRICES INCLUDE GST MARKET CENTRE Cash in your surplus gear. Advertise it here in Silicon Chip. CLASSIFIED ADVERTISING RATES Advertising rates for these pages: Classified ads: $27.00 (incl. GST) for up to 20 words plus 80 cents for each additional word. Display ads: $49.50 (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 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:___________________ 102  Silicon Chip FOR SALE More control solutions for you: NEW Radio Modules: Zigbee Radio Modem 1km, Bluetooth Serial Modem 100m. NEW Ethernet Modules: Ethernet to RS232/RS422/RS485 1, 2, 4 & 8-port Modules. NEW Protocol Gateways: Lonworks to Modbus, Profibus to Modbus, Can (J1939) to Modbus, AB-DF1 to Modbus, Hart to Modbus and more. NEW M325 Microstepping Bipolar Stepper Driver only $99. NEW 500oz-in plus Stepper Motor: may not be the fastest motor on the block but it has real grunt. NEW USB 8 Relay and 4 isolated input card. NEW 20-Amp DC Motor Speed Con­ troller. Low Cost Dual DC Amplifier Kit: per­ fect for Data Acquisition. Amplify signals from 1.5 to 10 or reduce signals by a factor of 0.7 to 0.1. Electronic Thermostats with digital temperature display, 2 control relays. Can be used in heating and cooling. NTC thermistor or J T/C or Pt100 sensors. Isolated and Non Isolated RS232 to RS485 converters. USB to RS422/RS485 converter with 1500V isolation, RTS or Auto Data Flow control. Signal Conditioners – non isolated siliconchip.com.au Satellite TV Reception VIDEO - AUDIO - PC International satellite TV reception in your home is now affordable. Send for your free info pack containing equipment catalog, satellite lists, etc or call for appointment to view. We can display all satellites from 76.5° to 180°. distribution amps - splitters digital standards converters - tbc's switchers - cables - adaptors genlockers - scan converters bulk vga cable - wallplates DVS5c & DVS5s High Performance Video / S-Video and Audio Splitters AV-COMM P/L, 24/9 Powells Rd, Brookvale, NSW 2100. Tel: 02 9939 4377 or 9939 4378. Fax: 9939 4376; www.avcomm.com.au MD12 Media Distribution Amplifier QUEST ® C O N T R O L S MS120 Quest AV® VGA Splitter VGS2 HQ VGA Cables The world’s lowest cost controller with inbuilt operator interface AWP1 A-V Wallplate Come to the specialists...  12 digital I/O  2 line LCD  5 push buttons  Easy to program QUESTRONIX ® 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 $120 w/o LCD. $164 w/LCD. Developer’s kit $197 Developer’s Kit includes programming cable & software Made in3/5/06 Australia -1:10 used world-wide SPK360 PM Page 1 splat-sc.com ELNEC IC PROGRAMMERS High quality Realistic prices Free software updates Large range of adaptors Windows 95/98/Me/NT/2k/XP 20 years experience! HI-FISPEAKER REPAIRS YOUR EXPERT SPEAKER REPAIR SPECIALISTS CLEVERSCOPE USB OSCILLOSCOPES SPK360 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! tel: 03 9647 7000 www.speakerbits.com and isolated: Convert thermocouples, RTDs to 4-20mA or 0-10V. Fully programmable. Stepper Motors: we have a selection of Stepper motors for hobby and high torque CNC applications. DC Motors for both hobby and high torque applications. DC, Stepper and Servo Motor controller kits. Serial and Parallel Port relay controller cards. PIC MicroProgrammers: serial and USB port operated. Switch Mode, Battery Chargers and DC-DC converters. Full details and credit card ordering siliconchip.com.au 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 IMAGECRAFT C COMPILERS ANSI C compilers, Windows IDE AVR, TMS430, ARM7/ARM9 68HC08, 68HC11, 68HC12 GRANTRONICS PTY LTD www.grantronics.com.au available at www.oceancontrols.com.au Helping to put you in control. ELECTRONICS AUSTRALIA: 1975 to 2000 25 volumes 96% complete plus lots of ETI and others $350.00 the lot ONO. nagybert<at>bigpond.net.au continued next page www.dontronics.com has 300 selected hardware and software products available from over 40 world wide manufacturers, and authors. Olimex Development Boards & Tools: ARM, AVR, MAXQ, MSP430 and PIC. Atmel Programmers And Compilers: STK500, Codevision C, Bascom AVR, FED AVIDICY Pro, MikroElektronika Basic and Pascal, Flash File support, and boot loaders. PICmicro Programmers And Compilers: microEngineering Labs USB programmers, adapters, and Basic Compilers, DIY (Kitsrus) USB programmers, MikroElektronika Basic, Pascal, DSpic Pascal Compilers, CCS C, FED C, Hi-Tech C, MikroElektronika C, disassembler and hex tools. CAN: Lawicell CANUSB, CAN232 FTDI: USB Family of IC ‘s. FT232RL, FT2452RL, also BL and others. 4DSystems LCD/Graphics: Add VGA monitor, or OLED LCD to your micro. Simple Serial I/F. Heaps And Heaps Of USB Products: TTL, RS-232, RS-485, modules, cables, analyzers, CRO’s. Popular Easysync USB To RS-232 Cable: Works when the others fail. Only one recommended by CBUS. Money back guarantee. www.dontronics-shop.com June 2007  103 Do You Eat, Breathe and Sleep TECHNOLOGY? Opportunities for full-time and part-time positions all over Australia & New Zealand Jaycar Electronics is a rapidly growing, Australian owned, international retailer with more than 39 stores in Australia and New Zealand. Our aggressive expansion programme has resulted in the need for dedicated individuals to join our team to assist us in achieving our goals. We pride ourselves on the technical knowledge of our staff. Do you think that the following statements describe you? Please put a tick in the boxes that do: Knowledge of electronics, particularly at component level. Assemble projects or kits yourself for car, computer, audio, etc. Have empathy with others who have the same interest as you. May have worked in some retail already (not obligatory). Have energy, enthusiasm and a personality that enjoys helping people. Appreciates an opportunity for future advancement. Have an eye for detail. Why not do something you love and get paid for it? Please write or email us with your details, along with your C.V. and any qualifications you may have. We pay a competitive salary, sales commissions and have great benefits like a liberal staff purchase policy. Send to: Retail Operations Manager - Jaycar Electronics Pty Ltd P.O. Box 6424 Silverwater NSW 1811 Email: jobs<at>jaycar.com.au Jaycar Electronics is an equal opportunity employer and actively promotes staff from within the organisation. Advertising Index 555 Electronics............................. 71 Altronics.........................loose insert Amateur Scientist CDs............... IBC Av-Comm................................... 103 Conexus....................................... 14 Defence Force Recruiting.............. 5 Dick Smith Electronics............ 32-37 Dontronics.................................. 103 RFMA RF Modules Australia Low Power Wireless Connectivity Specialists NiM2-434.650-10 Applications: TX2H-433-64 Rural UHF FM Transmitter UHF Narrowband Transceiver Utilities In Stock NOW! In Stock NOW! Industrial Range: 500m Range: 500m Commercial Power: 25mW Power: 10mW Data rate: 64kbps Government Data rate: 10kbps 33mm x 23mm x 12mm Meter Reading Receiver: RX2A-433-64 RADIOMETRIX: Low Power, Licence Exempt Radio Modules RF Modules Australia. P.O. Box 1957 Launceston, TAS., 7250. Ph: 03-6331-6789. Email: sales<at>rfmodules.com.au. Web: rfmodules.com.au Ecowatch.................................... 103 Elan Audio.................................... 16 Farnell InOne.............................. 2-3 Futurlec........................................ 77 Grantronics................................. 103 Harbuch Electronics..................... 57 Ian Cousins.................................. 97 Instant PCBs.............................. 104 Jaycar........................ IFC,49-56,104 JED Microprocessors..................... 7 Laservision................................... 73 Len Wallis..................................... 17 Measurement Innovation................ 9 Microgram Computers.............. OBC DOWNLOAD OUR CATALOG at 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 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 PCBs MADE, ONE OR MANY. Any format, hobbyists welcome. Sesame Electronics Phone (02) 9593 1025. sesame<at>sesame.com.au www.sesame.com.au LEDs! New old stock standard brightness and superbright brand name LEDs from just a few cents each. Cree X-Lamp XR-E LEDs $14.50. TA8050P bridge DC motor drivers $1.50. 20 x 2 OLED displays $39. Also LED and Nixie clock kits and all sorts of other stuff. www. ledsales.com.au 104  Silicon Chip WANT ED Person with contract projects experience in Microchip, or similar products programming, along with Electronics & PCB design expertise, for smaller product development projects. You would also require the ability to build prototypes, to a functional test stage. RS232 & RS485 knowledge an advantage. Please reply in the first instance to: engineering<at>irock.com.au MicroZed Computers.................... 47 Ocean Controls.......................... 102 Quest Electronics....................... 103 Radio & Hobbies DVD Archive..... 77 RCS Radio................................. 104 Richard Foot Pty Ltd.................... 80 RF Modules................................ 104 Sesame Electronics.................. 104 Silicon Chip Binders..................... 38 Silicon Chip Bookshop........ 100-101 Silicon Chip Subscriptions........... 81 Speakerbits................................ 103 Splat Controls............................. 103 Technic....................................... 102 Trio Smartcal................................ 41 Trusys......................................... 102 KIT ASSEMBLY NEVILLE WALKER KIT ASSEMBLY & REPAIR: • Australia wide service • Small production runs • Specialist “one-off” applications Phone Neville Walker (07) 3857 2752 Email: flashdog<at>optusnet.com.au Wagner Electronics...................... 71 Worldwide Elect. Components... 104 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