Victor,

   I am down to my last three workable RX8 coils and
   one of those might be dead.

   Here is the schematic on the GM coils.
   Why do you think they ran a separate signal ground.


   Paul Lamar

   The GM coils do the same thing. Retrigger with as much as
   2.2 K in series. However they only limit the in put trigger
   to 5 volts from five. The schematic calls out a .05 uf across
   the trigger line. That seems to help.

   It also seems to be highly configuration sensitive.

   By that I mean how the wires are placed.

   Perhaps the close proximity to the spark is feeding
   back to the trigger. In the car there would be
   a short piece of spark plug wire to the spark plug.

   In any event the GM coils seems to be more robust but they
   don't like a dwell time less than 5 milli seconds.

   I'll get some spark plugs wires and move the spark away
   from the trigger input.

   I also moved the battery and the coil a couple of feet away
   and shielded the trigger wire. All this changes things.

   IMHO coils should not have electronics in them.
   MSD ignitions do not do that.


   Paul Lamar


 Paul

 On 12/29/10 you posted Part 3 on using the Denso GM coil and had run it
 up to
 12,000 rpm and showed a spark plug at 9,000. How does this jive with the
 latest
 concern that it takes 5ms to charge these coils, which corresponds to
 7,500,
 yet the coils apparently work well at 9,000?

 Dan F



 I did not have the scope on the trigger wire so it was probably self
 triggering at some lower frequency. I was just looking at the dial of
 the signal
 generator. They will do that. They will sit there and spark on thier own
 until they die. It does this at dwell time frequency. In the case of the
 GM 5 millisecond period. If I had let it cook longer it would probably
 have
 committed suicide. :)

 It had me fooled :)

 Paul Lamar

May I suggest a less expensive and perhaps more reliable way of getting
an ignition spark.
http://www.fairchildsemi.com/markets/automotive/auto_igbt_ig_std.html#ign
Use these or similar from other manufactures and a standard or wasted
spark coil.

Sample of chip.

csmale

That appearers to be the chip used in the Mazda and maybe the GM coil.
That would work but you would have to find a stand alone inductive  coil that will build max current in about 3 ms. Do you know of any fast charging
stand alone coils?

Paul Lamar