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MARKET CENTRE Cash in your surplus gear. Advertise it here in SILICON CHIP Announcing Pioneer Hill Software FOR SALE SpectraPLUS 24bit DAQ ADC spectrogram, t.h.d. and i.m.d. analysis, f.f.t, acoustic tools, 3D surface plot, sig. gen. etc. Fully shielded SpecctraDAQ200 ADC/DAC 24bit/192kHz dual channel, Wolfson. AKM converters … USB3 interface to laptop/PC As 2ch. 24bit recorder t.h.d. = 0.002%max see : www.spectraplus.com Order direct, USA contact : John Pattee (pioneer<at>spectraplus.com) Local agent : DSCAPE Melbourne s/w , h/w package ca. USD $1500 Aus. Distributor : Julian Driscoll CEO jcdrisc<at>tpg.com.au for support PCB MANUFACTURE: single to multi­ layer. Bare board tested. One-offs to any quantity. 48 hour service. Artwork design. Excellent prices. Check out our specials: www.ldelectronics.com.au tronixlabs.com - Australia’s best value for hobbyist and enthusiast electronics from adafruit, DFRobot, Freetronics, Raspberry Pi, Genuino and more, with same-day shipping. LEDs, BRAND NAME and generic LEDs. Heatsinks, fans, LED drivers, power supplies, LED ribbon, kits, components, hardware, EL wire. www. ledsales.com.au Shop at www.siliconchip.com.au for details and to place your order, or phone (02) 9939 3295. PCBs MADE, ONE OR MANY. Any format, hobbyists welcome. Sesame Electronics Phone 0434 781 191. sesame<at>sesame.com.au www.sesame.com.au KEITH RIPPON KIT ASSEMBLY & REPAIR: * Australia & New Zealand; * Small production runs. Phone Keith 0409 662 794. keith.rippon<at>gmail.com PCBs & Micros: SILICON CHIP Publications can supply PCBs, programmed microcontrollers and other specialised parts for all recent projects and some not so recent projects. Visit the Online KIT ASSEMBLY & REPAIR DAVE THOMPSON (the Serviceman from SILICON CHIP) is available to help you with kit assembly, project troubleshooting, general electronics and custom design work. No job too small. Based in Christchurch, NZ but service available Australia/NZ wide. Phone NZ (+64 3) 366 6588 or email dave<at> davethompson.co.nz VINTAGE RADIO REPAIRS: electrical mechanical fitter with 36 years ex­ perience and extensive knowledge of valve and transistor radios. Professional and reliable repairs. All workmanship guaranteed. $10 inspection fee plus charges for parts and labour as required. Labour fees $35 p/h. Pensioner discounts available on application. Contact Alan on 0425 122 415 or email bigal radioshack<at>gmail.com ADVERTISING IN MARKET CENTRE Classified Ad Rates: $32.00 for up to 20 words plus 95 cents for each additional word. Display ads in Market Centre (minimum 2cm deep, maximum 10cm deep): $82.50 per column centimetre per insertion. All prices include GST. Closing date: 5 weeks prior to month of sale. To book, email the text to silicon<at>siliconchip.com.au and include your name, address & credit card details, or phone Glyn (02) 9939 3295 or 0431 792 293. Ask SILICON CHIP . . . continued from page 102 per volt (given by 0.004 x 4 = 0.016). For 10kV, that is 160 turns minimum. The SILICON CHIP pulse transformer has seven turns for its primary, 250 turns on the secondary, 350V input and 3.6kV output. 7T ÷ 350V = 0.02, 250T ÷ 0.02 = 12,500V. I find this confusing. Is there a reason for this difference or is there a mistake in the article? siliconchip.com.au Is it supposed to be 17 turns? Back in October 1986, Electronics Australia published a Fence Controller (EA86ef11) by Colin Dawson. This controller has a pulse transformer with 40 turns on the primary and 500 turns for the secondary with 250V input and 5kV output. 40T ÷ 250V = 0.16, 500T ÷ 0.16 = 3125V. This is confusing as well. Should this be 30 turns or is there some reason for this difference? The EA controller has a 30µF capacitor, the same as the arrangement I have with the components from the Lanstar energiser. The only real difference is the voltage applied to the capacitor and it looks like they left scope with the voltage to make it a bit more powerful. The pulse transformer would have been much the same size as the one from the Lanstar and the one that I am planning to wind. I would like some advice regarding the winding of this transformer. I will be pushing 550V into the transformer and with 500 turns for the secondary July 2016  103 Notes & Errata Pocket TENS Unit for Pain Relief, January 2006: the IR2155 IC used in this project is now obsolete and difficult to obtain. According to International Rectifier, the IRS2153DPBF is the recommended replacement (see https://ec.irf.com/v6/en/ US/adirect/ir?cmd=catProduct Detail&productID=IR2155). Ask SILICON CHIP . . . continued from page 103 and 30 turns for the primary I figure the output should be close to 10kV. Now given that the minimum number of turns for the secondary with 10kV output is 160 turns, it may be possible to get away with fewer than 500 turns. I was thinking of say 320 for the secondary and 18 for the primary; this should lower the impedance and take less time to wind. Besides, I have plenty of 0.8mm diameter wire and this is the most I can get on to the former unless I go to 0.6mm. My questions are as follows: (1) If I lower the number of turns, will it shorten the pulse length or affect the output voltage? (2) Could it possibly overload the transformer? (3) Is it better to stick to 500 turns or possibly more? (D. D., via email). • The turns ratio of the output pulse transformer was wound to comply with the Australian Standards AS3129. It states that the energy produced by an electric fence is limited to a maximum of five Joules into a 500-ohm load. Open-circuit load voltage is restricted to 10kV (ie, >1MΩ load in parallel with 100pF). The turns ratio does not necessarily set the voltage that will be delivered to a 500Ω load. The output depends on the pulse width, the impedance of the transformer and the inductance of the windings. If you use fewer turns on the transformer primary, the transformer may deliver less energy (fewer Joules) to the output. With an unknown core, you will have to experiment with the number of turns and the turns ratio. The output must ultimately comply with AS3129 for safety’s sake. Champion for a guitar practice amplifier I was wondering if the Champion (January 2013) and the Champ (February 1994) amplifiers would be compatible with an electric guitar in their kit form, as sold at Jaycar and Altronics. I am interested in building a simple guitar practice amplifier and both are stocked by stores near me. (O. M., via email.) • The Champion from January 2013 would be quite suitable. This has sufficient output power for good volume through efficient loudspeakers and the input sensitivity should be sufficient for a guitar without needing the preChampion that is incorporated on the Champion PCB. We don’t recommend the Champ from February 1994 for a guitar practice amplifier as the input impedance is too low and output power is insufSC ficient. Next Issue The August 2016 issue is due on sale in newsagents by Thursday 28th July. Expect postal delivery of subscription copies in Australia between July 28th and August 10th. Advertising Index Allan Warren Electronics............ 103 Altronics.................................. 72-75 Australian Exhibitions & Events.... 31 Digi-Key Electronics....................... 3 DSCAPE.................................... 103 Emona Instruments.................... IBC Front Panel Express..................... 15 Hare & Forbes.......................... OBC Jaycar .............................. IFC,49-56 Keith Rippon Kit Assembly ........ 103 LD Electronics............................ 103 LEDsales.................................... 103 Master Instruments.................... 103 Microchip Technology................... 11 Minitech Engineering..................... 9 Mouser Electronics......................... 5 Ocean Controls............................ 13 PCB Cart........................................ 7 Pinfold Health Services................ 43 Sesame Electronics................... 103 SC Radio & Hobbies DVD.......... 101 SC Online Shop...................... 25,91 Silicon Chip Binders................ 66,79 Silicon Chip Subscriptions........... 67 Silicon Chip Wallchart.................. 83 Silvertone Electronics.................. 15 Tronixlabs.............................. 45,103 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 Competition & Consumer Act 2010 or as subsequently amended and to any governmental regulations which are applicable. 104  Silicon Chip siliconchip.com.au