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Re: Small number of turns in primary

Original poster: "Bob simms by way of Terry Fritz <twftesla-at-uswest-dot-net>" <fsimms-at-ghg-dot-net>

> > One advantage of having a low inductance with a few turns in the
> > primary is that you get to use a larger cap. The larger the cap the
> > more energy you can store in the cap to be discharged into the coil.
> But the same argument applies to a smaller capacitance run at a much
> higher voltage doesn't it?


> > This would take a very expensive capacitor though.  Finkelstein showed
> > with a .6 coupling that the entire energy of the cap can be put into
> > the coil in 3/4 of a cycle. This creates a monstrous bolt of energy.
> > Jay did this with a coil he built which had a 120 turn 3 ft high
> > secondary and a 4 turn primary. His secondary was about a foot in
> > diameter. He generated single shot sparks that were as long as his arm
> > and as thick. He used litz wire on his secondary to get the resistance
> > down.  His coil was set up to generate just a single shot. Jay used a
> > static pressurized gap with Argon and sodium hexifluride gas. This gap
> > is self quenching. He used carbon ball electrodes. Jay had 12 neon
> > transformers driving a .06 uF 60kv cap that he had built for him.
> What type of primary did he use and how was it arranged to hit k=0.6?
> Also, what voltage did his gap fire at?

He had 4 turns of a 1/2 inch welding wire around the coil.  The diameter was
about 40 inches. (Guess) with a spacing of about 5 inches (also a guess).
The secondary was 13.5 inches and 33 inches tall.  I don't know what voltage
his gap fired at.  His gap adjusting methods were with a rubber glove and a
screw on the gap.  He was so nervous around the thing I am not sure he got
it dialed in to the maximum. LOL

The gap was quiet, but the single shot of the secondary had a report like a

His tuning techniques are in his paper:
. Reed, JL; "Greater Voltage Gain for Tesla Transformer Accelerators"; Rev.
Sci. Instrum.; vol 59 #10; Oct 1988

A zip file of pcx files of his paper is at:

He talks about how to set the coupling in that paper.