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Re: The incredible inedible ignition coil

Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-uswest-dot-net>" <evp-at-pacbell-dot-net>

Tesla list wrote:
> Original poster: "sundog by way of Terry Fritz <twftesla-at-uswest-dot-net>"
>   Hi All,
>         Yes, hokey subject, but it's been stuck in my head all day, just
> I'd pass it on! ;)
>   Had myself an idea yesterday at work.
>     Basically, I figured an oil-cannister type ignition coil is a mini
> 1-eared polepig.  So I grabbed my 2 coils (leftovers, cost me $26 each new),
> my "bargain bin" dimmer from home depot ($1), and a couple of runcaps
> salvaged from an AC unit.
>   I hooked up the auto coils anti-parallel (hook the negative terminals
> together, that's where the secondarys are grounded to), and put that in
> series with the runcap and dimmer.  I added 2 bent coathangers for a mini
> jacob's ladder.
>   At 5uf, power draw was less than 1A (didn't register on my analog
> amp-clamp).  thin purple sparks, didn't climb
>  at 25uf power draw was around 2.2A, nice yellow NST type arc with a
> blue-purple core and raspy sound. climbed to be about 1.5" long
>  at 50 uf power draw was around 4.6A, good thick yellow arc, still raspy.
> with the purple core.  climbed to be about 2"
>  at 150uf (couldn't help myself), power draw was ~9-10A (a bit jumpy), good
> thick 2.5" arc (the widest point in the JL).  Still raspy, with the purple
> core.
>   at 5uf, there was no detectable heating
>  at 25uf, there was noticeable heating after 5 min of cont. runtime, and the
> cans were fairly hot after 10 min of cont. use
>  at 50uf there was noticeable heating after 2 min of use, and the cans got
> hot in about 4-5 min (too hot for my tastes, i don't want a pair of
> oil-filled cannisters popping on my workbench)
>  at 150uf the cans got hot in about 1 min.  Cool offs after each run were by
> slapping the coils (these have metal cannisters) in the fridge for 1/2 hour.
>  So at ~200 watts, they run *very* well.  at ~500 watts they run well for
> short runs, and at 1kva they buzz loudly, vibrate around on the table
> (they're surely saturated at that point) and generally manage freakish
> output for a car coil.   I don't know how well the scr based dimmer will
> hold up in TC service.  Mine is a cheapie 200 watt unit I think (horribly
> overdriven, but it survived).
>   My thoughts are to run the coil at a much higher freq (a V8 running
> 3000RPM fires 400x a second, so I know for a fact the coils cores work well
> at higher frequencies).  The problem is that an alternator (Oh NO!! That 3
> phase thing again!!!) will literally stall a 5hp gas motor trying to run a
> heavy load (and I blew up an alternator, this was long ago).  A beefy DC
> supply with either a mechanical points system (noisy) or a SCR setup (will
> probably fry from the backlash of the tank circuit) seems to be a good
> answer, allowing me to set my pulse frequency.
>    So, given some time (or if someone will test it) to see how the SCR in
> the dimmer handles tesla duty, the anti-parallel ignition coils were a very
> stable power source.  I'd put the voltage about 15+kv (it'd jump ~1/2"), and
> enough current to push an arc to about 1.5" at ~200w input.  The coils
> survived the 1kva pounding with flying colors.  internal construction-wise,
> the base of the secondary (looks like 40ga wire) is connected to the
> negative terminal of the primary (22ga).  oil-impregnated kraft paper
> insulating the windings, and a thin steel laminate core. The core floats at
> HV in the coils I have (?!), but it's insulated against it and it's given me
> no problems in actual auto service, so it must be fine.  So for the "NST
> Challenged", this may end up being a viable tank tranny for low powered
> coils (and intermittent medium duty).  The weakest link I can see is the
> SCR.
>  Hope this helps someone, I welcome comments!
	Something wrong here! You should be doing MUCH better!!!!!  I have
tried exciting a GM High-Energy ignition coil with a light dimmer in
series with a 3 ufd capacitor.  Get 2" sparks, which is about the
insulation limit in air - sparking to core.  These coils are readily
available in used auto parts stores around here, and come from Buick,
Cadillac, and Olds distributor caps.  Going price seems to be from 3 to
5 bucks for the whole cap, remove the transformer yourself.  I have one
assembly consisting of two of them with the secondaries in series and
the primaries in parallel.  Can easily get hot 5" sparks.