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Re: Terry's GM HEI Coil Update.

Tesla List wrote:
> 
> Original Poster: "Jim Lux" <jimlux-at-earthlink-dot-net>
> 
> ----------
> > 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.
	
	As for stacking a bunch of coils in series with independent power
supply for each pair, that should work fine but wouldn't be the most
convenient thing to build and operate.  Why doesn't someone here try
it?  Would think that the drivers could all be pulsed at the same time
by a flash, as you suggest.  Perhaps small photo-SCR's could be used to
trigger the main switch.

	As for the last idea, the insulation is too poor to permit that sort of
thing.  The coil as built has quite a respectable closed magnetic
circuit steel core, and to approximate similar operation with a long bar
is probably impossible.  First problem I can see is that all of the
coils would experience a core-to-inside of the winding breakdown.

Ed

<<<< This would not be a Tesla coil anyway!!  I do want to keep it a Tesla
coil in any case.  I do have a photo of a cut in half GM HEI coil.  E-mail
me and I will send it to anybody.  It is about a 175K JPG file but it is
pretty fine.  The insulation is really very good even at super high
voltages... - Terry >>>