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Advertising Index Altronics.................................39-42 Blackmagic Design....................... 7 Dave Thompson........................ 111 DigiKey Electronics....................... 3 Emona Instruments.................. IBC Jaycar....................IFC, 9, 13, 26-27 ..................................58-59, 93, 101 Keith Rippon Kit Assembly....... 111 Lazer Security........................... 111 LD Electronics........................... 111 LEDsales................................... 111 Microchip Technology.............OBC Mouser Electronics....................... 4 PCBWay....................................... 11 PMD Way................................... 111 Quest Semiconductors................. 8 SC GPS Analog Clock............... 109 SC Ideal Bridge Rectifiers........... 92 Silicon Chip 500W Amplifier..... 67 Silicon Chip Binders.................. 91 Silicon Chip Shop............ 102-103 The Loudspeaker Kit.com.......... 12 TME............................................. 10 Wagner Electronics..................... 99 be realised in all cases with a 1V RMS input signal. To increase the gain, use the following component values in place of those shown on the circuit and overlay diagrams: R1 & R4 = 7.5kW, R2 & R5 = 1.2kW and C1 & C2 = 100pF. If you are not using the 5V regulator, the 100W 5W resistor is not required. You probably don’t need the 330W 5W resistor that bleeds the negative supply, as this is to counterbalance the positive supply being discharged due to the load from the 5V supply. Since the 5V supply is unused when powering just the headphone amplifier board, the negative supply would be discharged faster with the 330W resistor, so it’s best to leave it off. E30 transformer for Electric Fence Driver I am building the High-Powered Electric Fence Controller design by John Clarke (April 1999; siliconchip. au/Article/4577). One of the parts is an E30 Transformer Assembly, which 112 Silicon Chip I cannot locate anywhere. I have tried major electronic components suppliers, who all say they have never heard of it. The information in the plans is not really descriptive of the voltage in and out of either transformer. Do you know where to find this transformer or any further information to help me find an alternative? (D. D., Portland, NSW) ● The E30-type transformer form factor is a standard created by EPCOS/ TDK some time ago; matching parts are still being made today. The E30 transformer bobbin is 35.4 × 35.4 × 20mm. However, the currently available parts differ slightly from those we specified in that project around 25 years ago. Instead of five pins on each side, there are seven. You may need to cut off the extra pins to fit into the PCB. RS Components (https://au.rs-­online.com) sells the cores and bobbin, but they require you to buy a minimum of 10. For this project, you will need two bobbins and four cores, so you will have eight bobbins and six cores spare. The EPCOS B66232B1114T001 bobbin is RS Stock No 125-3622, while the EPCOS B66319G0000X130 cores are RS Stock No 125-3657. The cores can be held in place with a cable tie, as shown in the article, since RS is out of stock of the clips (‘yokes’). If you particularly want to use the clips, you can get them from Mouser (Cat 871-B66232A2010X) or DigiKey (Cat 495-5379-ND). The input and output voltages are not specified for these since the transformer needs to be wound, and those voltages depend on how it is wound. The parts you buy are just the bobbin and cores, not a complete transformer with windings. Winding details are provided in the April 1999 article (siliconchip.au/Article/4577). Changing Darlington to IGBT in ignition system I realise some time has passed since you published the Programmable Ignition System (March-May 2007 issues; siliconchip.au/Series/56). Still, I believe my question should be simple to answer. I have looked at the circuit diagrams for the High-Energy Ignition System (November-December 2012), which uses an IGBT coil driver instead of the Darlington driver in the earlier design. Can I change the Programmable Australia's electronics magazine Ignition to use an IGBT coil driver by simply driving the High Energy Ignition circuit from output pin 9 of the PIC? That would eliminate the 1nF ceramic capacitor, 470W resistor and L2 and change the 10W resistor to 1kW. I have boards and most of the parts for six of these ignition units, and I thought it would be a better way to go. Does anything else need to be modified for this to work? (S. M., Leederville, WA) ● It is a simple question but not necessarily a simple answer. The IGBT coil driver may work in this case; however, we haven’t tested that change. Due to the programmable ignition advance and retard features, the microcontroller is more susceptible to electromagnetic interference (EMI), which can cause the ignition timing to become erratic if it is not managed correctly. To prevent this, there is a filter at the output of the Programmable Ignition before the coil driver. This comprises the 10W resistor and 1nF capacitor, plus inductor L2 and the 470W series resistor. The filter reduces EMI entering the Programmable Ignition microcontroller. Consequently, you should not remove those components; only the 470W resistor should be changed to 1kW to drive the IGBT. Another problem when using the IGBT is that the gate connection of the IGBT to the Programmable Ignition is at a considerable distance. That can cause the IGBT to fail due to oscillations when firing the coil or gate damage from high induced voltage. That’s due to the inductance of the wiring forming a resonant circuit with the IGBT gate capacitance. It is worth giving the IGBT coil driver a go as it reduces the number of parts in the coil driver to a minimum. However, if it doesn’t work well, you may need to revert to using the original coil driver with the Darlington. A shielded cable will be required between the Programmable ignition output and the IGBT gate to reduce voltage spikes at the gate. The shield should be connected to the IGBT emitter. SC Next Issue: the March 2024 issue is due on sale in newsagents by Monday, February 26th. Expect postal delivery of subscription copies in Australia between February 23rd and March 15th. siliconchip.com.au