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Home made electronic ignition

Discussion in 'General Electronics Discussion' started by discomark10, Sep 18, 2013.

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  1. discomark10


    Sep 18, 2013
    Hi guys, new to the forum and thought I'd say hi and share my lil project I'm going to start.

    I've had a Discovery 1 for about 4 years now I believe, and 2 years of that was spent rebuilding it, which included the Rover 3.5 v8.

    I'm going to build a controller utilizing the 8 tooth trigger wheel on the original Lucus distributor to trigger the spark as it does the mechanical and vac advance for me (I may modify this to be electronically controlled at a later date depending on how it goes, but for now it will do what I want!).

    I'll be using Ford (wasted spark) coil packs as I know they work well and are readily available and also some electronic wizardry!

    Out of curiosity, has anyone done one like this and if so how did it work for you?
    I know there are many off the shelf kits out there but they cost alot, and I like to make things for myself as its more rewarding and you learn more along the way!

    I'll be honest, my electronic knowledge will be basic compared to many of you on hear and the main brain behind the design of the circuity is my old man, he has had alot of experience with electronics due to his work and hobby's.

    Since starting this project I've since built and tested the coil driver (which works, and also played with a hall sensor to see how well it works on a trigger wheel.
    I used a magnet behind the sensor to boost the pickup of the steel wheel as it struggled without.
    one thing to note is (at least with a strong magnet) you need to play with the distance of the magnet to very the pickup strength on the wheel, otherwise it fails to notice the gap between the teeth, or fails to pick it up at all. But all in all once you have the spacing right it works great!

    Feel free to reply with any help/suggestions and (constructive) criticism.

    Cheers Mark
  2. duke37


    Jan 9, 2011
    I made a transistorised ignition some 30 years ago and also bought a Sparkright unit.
    These were based on self oscillating invertors using the new 2N3055 power transistors. The inverter charged a capacitor which was discharged throuh the coil with a SCR. This put a short on the inverter output but this was OK since it was self oscillating. Both these units worked well.

    More recently I have made an inverter to provide 300V for a valve radio. Fot this I used a CMOS 4047 oscillator/divider driving a pair of MOSFETs. The transformer core was from a TV line output transformer. This type of inverter should not be shorted so will need to be shut down for a period when the SCR is fired.

    You do not say where you are but the parts should be less than £10 in the UK.

    A flyback converter can be short circuited and such an ignition circuit is partially described in "Power Supply Handbook" by John Fielding ZS5JF (ARRL and RSGB).ISBN 1-905086-21-0
  3. discomark10


    Sep 18, 2013
    Thanks for the reply Duke, that may have given us a solution to the dwell timing, before I was going to have to design a time delay to account for low voltage and dwell angle.
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