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 .
No but maybe a CD ignition coil would work if the dwell is
controlled.Or a
coil requiring a resistor and use it without a resistor
c smale
The CD coils might work but so does any old fashion inductance coil
work with a CD. The coil becomes merely a pulse transformer when
used with a CD system. In my experience with CD systems dating back
to the early 60's just about any ignition coil worked.
Too bad I cannot find a chemical to dissolve the epoxy
potting compound in failed RX8 coils. I'll bet they are
a dime a dozen. I could use them with a separated IGBT
switch :)
Paul Lamar
Mogas with ethanol famously dissolves the epoxy in fiberglass epoxy fuel
tanks. Probably takes time to soak in.
Al Rees
I think I'll try it
Paul Lamar
Ethanol works on polyester resins but not epoxy, couldn't you get any ether?
John Evans
I have not tried John.
The DEA would be on me like bees on Honey :)
Paul Lamasr
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