Re: BIGGG COIL'S NEW PROBLEM

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Ed Phillips <evp@xxxxxxxxxxx>

"Ed,
I just got some 1.0 mF 2500WVAC MO caps that I am planning to use to
drive
an ignition coil the way you describe off the 120 mains in series with a
600 watt dimmer. You say you pulled 30 amps. Did this trigger your
circuit
breaker? Are there any "anomalies" I need to look out for that you can
warn
me about?  My ignition coils are very robust racing coils from my drag
racing days. Three of them are rated at 50 kV and one is rated 60 kV.
They
are much larger than standard coils and contain a lot of cooling oil. I
believe I can stress them pretty hard without worrying about burning
them
up. Even if I kill one, I have 4! You mention line glitches. Do I need
to
put an EMI filter between the plug and the dimmer to protect my house
wiring? Any advice will be greatly appreciated. Regards.
Paul
Think Positive "

	No circuit breaker problems.  The peak current was about 30 amps but
the duration of the spikes (two per cycle, of alternating polarites) was
only a few microseconds.  As for capacitance, I've used up to six
microfarads on occasion.  As for the EMI filter, that would probably
increase the impedance of the line at the high frequencies corresponding
to the pulses and limit the peak current quite a bit.  A more practial
"filter" would be to put a couple of microfarads (AC rated for line
voltage) across the line instead.  The capacitor would supply the peak
currents.  I actually did that and it seemed to work OK. I never really
kept notes of what I was doing, but was able to get at least 4" sparks
from a back-to-back pair of junker GMHEI coils dunked in oil.

	I don't really like this circuit arrangement; only merit is
simplicity.  In my coil drivers I rectify (actually voltage double) the
line to get about 300 VDC and then use a quadrac to discharge the
charged pulse capacitor into the coil  This completely isolates the line
from the current pulses (except for small spikes due to the
capacitor-input doubler and also allows running the coil at a variable
repetition rate.  In my drivers I use inductive charging of the pulse
capacitor, which actually gives me 600 volts across it at the moment of
discharge.  If you're really interested I could send you schematics of
this driver, which is pretty easy to throw together.

Ed