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Re: Terry's GM HEI Coil Update.





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> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Terry's GM HEI Coil Update.
> Date: Tuesday, November 17, 1998 9:54 PM
> 
> Original Poster: Terry Fritz <terryf-at-verinet-dot-com>
> 
> Hi All,
> 
> 	Tonight I tested my new and improved Tesla coil made out of a General
> Motors High Energy Ignition coil.  This new coil uses a brand new HEI
coil
> and has much greater high voltage stand off capability.  Also the tuning
is
> improved and some instrumentation was applied to monitor its performance.

Since you are getting all those coils cheap, why not put together something
I designed (but never built, having moved on to other methods). Stack up 10
stages, each consisting of two coils back to back (e.g. 80-100 kV peak
output). For field control, something like a pizza pan between stages would
work nicely (except that pizza pans are too expensive: perhaps some other
source of round disks with rolled edges?). Put a battery on each stage to
power it. Drive all the stages with an opto isolated driver in synchronism.
If you can find them cheap, the plastic fiber optics stuff (1000 micron
core) would be nice, but I think you could also come up with a clever
scheme with a really bright IR led and an IR photo transistor on each
stage, and a plexiglas light pipe up through the stack. (or use a xenon
strobe to trigger it).

Conservatively, a standard ignition coil (not HEI) can store 100 mJoule, so
the stack of 20 is 2 J per shot. Run them at 400 Hz (= 6000 RPM for a 8 cyl
engine), and you are looking at 800W average power at 1 megavolt, or there
abouts.

If you are getting a joule per shot from the HEI's, then, all the better.

A typical 7AH 12 V gel cell battery is 84 Watt/hr. If the stage draws 80W,
you get about a half hour of run time per charge.

Another idea, although I don't know what the windings of an HEI coil look
like (someone post a photo?), but could you string a whole bunch of them in
series on one long iron or ferrite (a'la Sulaiman's iron filings and glue)
core and immerse the assembly in a long tank of oil (i.e. a piece of PVC
pipe). Then, drive the bottom with a suitable primary winding.