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Re: Terry's GM HEI Coil Update
Hi Scott,
> Original Poster: Scott Stephens <Scott2-at-mediaone-dot-net>
>
> At 06:37 AM 11/18/98 -0700, you wrote:
>
> >Original Poster: Terry Fritz <terryf-at-verinet-dot-com>
> ...
>
> >At these extreme test levels, I must wonder if the
> >output is getting near the lethal area.
>
> I SWAG chunks of exploding flesh, rather than plasma burns
>
> >I have simple 1/2 inch diameter steel rods for
> >a spark gap.
>
> How far apart are the rods? How do you get your gap working under 1KV?
>
> >The firing voltage varied
> >substantially so there is improvement to be made to get a more consistent
> >firing voltage. I'll have some experimenting to do with this new gap
> >application!
>
> For such low firing rates, you might consider a strobe light, using its
> triggered flash tube as a spark gap. But IIRC, ratings are for a few
> thousand flashes
I actually tried using a xenon tube as the gap on a small coil once
but it isn't a runner. The tube (as Bert points out) loses badly
(which it is designed to do) and gets hot very quickly. I didn't
bother to trigger it - just let primary cap voltage rise until it
broke down around 2 - 3kV as I recall.
> > This was very interesting! The output voltage waveform always has a
very
> >high initial spike which is perfectly reproducible from bang to bang. This
> >initial spike is 50% higher than the next larger spikes.
>
> You mean this coil doesn't "ring up"? Its tightly coupled, ringing down? Or
> since the pulse is so long (10's microseconds) compared to typical TC's,
> that an output arc is already lit on the first bang damping subsequent
> primary-secondary energy transfer.
It is pretty tightly coupled. The cap would virtually go straight
into the output discharge.
Malcolm
<snip>