Dwayne Reid <dwayner <at> planet.eon.net> writes:

>=20
> Good day to all.
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> I've just been handed a project where the customer needs to have a=20
> spark suitable for igniting combustible gases.  This is an outdoor=20
> application and he wants a spark every few seconds.  The unit needs=20
> to run from a 12V battery that is charged with a solar panel - no=20
> outside power is available.
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> The obvious solution is to have a simple timer that drives an=20
> ordinary automobile ignition coil from a 12V battery.  I used to do=20
> stuff like this several decades ago.
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> But I always got better results when I used a Capacitive Discharge=20
> setup, where a small (1uf) capacitor was charged to a fairly high=20
> voltage, then dumped into the ignition coil's primary.
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> Fast forward a couple of decades - cheap Chinese-made CDI modules=20
> seem to be everywhere.  But I'll be darned if I can find one right now.
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> What I'm looking for is an off-the-shelf CDI module that doesn't=20
> consume a lot of power while its quiescent and that I can trigger=20
> with a 555 timer (or a PIC !!) every few seconds.
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> Does anyone have any idea where I can purchase something like this=20
> fairly inexpensively?
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> FWIW - I'm currently looking at a "2 STROKE RACE CDI IGNITION JOG=20
> Minarelli 1PE40QMB" module on eBay right now.  Its cheap at $8.99 but=20
> I'm pretty sure that its intended for magneto ignition rather than a=20
> 12V battery supply.  But something like that is what I'm looking for.
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> Suggestions greatly appreciated.
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> Many thanks!
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> dwayne
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Hi Dwayne,

The problem you will find with the cheap CDi units used in
scooter/moped/lawnmower engines is that the high voltage comes from a
winding in the generator (effectively a magneto) rather than being generate=
d
within the module.  The modules consist mainly of a capacitor, SCR and some
signal conditioning circuitry, but no high voltage inverter.  The really
fancy ones may have a micro to control the spark advance, but most of them
use an analog circuit to use either the rising or falling edge of the
trigger signal, depending on voltage (and therefore RPM).

Regards

Mike

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