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12v - 400v DC-DC convertor

Discussion in 'Hobby Electronics' started by Mark, Jul 6, 2003.

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  1. Mark

    Mark Guest

    i need a 400v supply to drive a multi spark CDI ignition. I was just
    wondering what the best switch mode topology to use is?

    I want it to be capable of 8 sparks per engine revolution with each spark is
    about 100mJ. At 10,000rpm this works out as 133W.. i think.

    I have had some experience with push-pull type convertors but that is about

    Yeah so what i waanna know is what type of switch mode supply would be
    suitable for this.


  2. Just a silly idea, what about using a 12 volt to 240 volt modified
    sine wave inverter, use a bridge rectifier and filter capacitor, will
    get around 340 V DC, but its really cheap to get a 150 W inverter
    around many places., see them at DSE, Jaycar and some Auto parts

  3. Bob M

    Bob M Guest

    Hi Mark,

    Silicon Chip, September 1997, page 18 had a good article on the
    construction of a multi-spark CDI. The power supply it used produced a
    reasonably regulated 300 volts. It would very easy to adjust the turns
    ratio and modify the regulator to output 400 volts. I would also
    suggest using a bigger e core transformer and heftier power
    transistors/heat sink. Make sure you use a coil that was designed for
    400 volts @100mj on the primary, otherwise, expect to go through a lot
    of them. They will break down and fail quickly.

    Are you sure about 8 sparks at 10,000rpm? Typically, at high rpm,
    ignitions produce only 1 or 2 sparks. I guess the reasoning is that if
    the cylinder hasn't fired and completely burned by the second spark,
    it is too late to fire it and get any usable energy from that
    particular revolution.

    Anyways, as a result of this article, I have designed an ignition
    system that I am installing on my 1970 Evinrude 60hp engine. I have
    much info that I can forward if you wish. Let me know.

    Regards, and Cheers from Canada

    Bob Morgoch
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