Need help with capacitor discharge ignition?

Discussion in 'General Electronics Chat' started by electronice123, Oct 3, 2009.

  1. electronice123

    Thread Starter AAC Fanatic!

    Oct 10, 2008
    I just bought a couple ignition coils from a 02 Honda CBR f4I (bullet bike).
    I bought the coils for a high voltage project. However, when I tried to drive them (using 12V pulsed DC) I had no high voltage coming from them.

    It seems these coils are made to be driven by a capacitor discharge, and I cannot find the capacitor value because they are built into the ECU.

    The coils have a primary resistance of 1.5 ohms, secondary resistance of 11.5K ohms, and a inductance of 2.38mH.

    I want to drive the coils from 100-10000Hz. Can anyone suggest a circuit to make these coils work properly? What cap values do I need?
  2. mik3

    Senior Member

    Feb 4, 2008
    Post your schematic to see if the circuit is correct.
  3. jpanhalt


    Jan 18, 2008
    The usual model CD ignition capacitor is 0.47 uF at 300 to 400V; however, some automotive coil-on-plug systems are quite different. That is a fairly large (physical size) capacitor. Something like 0.22 uF will also work. Be sure your coil is for CD ignition.


    Edit: I have attached two simple versions for models and and interesting pdf from ST.

    View attachment 12465

    View attachment 12466

    View attachment 12467
    Last edited: Oct 3, 2009
  4. electronice123

    Thread Starter AAC Fanatic!

    Oct 10, 2008
    Thanks for the help.

    One thing I am hoping to be able to do, is drive the coils so they produce multiple sparks. I found one circuit in particular here:

    The circuit in the above pdf does this, and I'm wondering if it can be done in a more simple way because I'm just looking to build something for some high voltage experiments. I want it to perform the multiple spark with changing polarity though???

    I don't understand how the polarity change is done? And if it is possible to do this with a more simple circuit???
    Last edited: Oct 3, 2009
  5. bountyhunter

    Well-Known Member

    Sep 7, 2009
    Can your 12V pulser source provide 8A? If not, you were not putting 12V pulses across the 1.5 Ohm primary, hence no spark. Ohm's Law has no sense of humor.....