RE: Big TC design


In the summer of 1997 I ran a coil with specifications very close to yours,
as shown:

Secondary:	15 1/2" x 60"  (56" wound length)  using #15 wire, about 76 mh
Toroid:		10" x 56"
Primary:	12 1/4 turns 20.5" I.D.,  51" O.D.
Capacitor:	.075 mfd

This coil ran using a 14,400 volt pole pig, with 280 VAC input resulting in
just under 17,000 VAC to the coil.  I could "almost" always achieve 11-12
foot sparks, occasionally 13 feet with one of those recorded on video.  This
did require 14-16 KW input.  The rotary spark gap used tungsten electrodes
and it was run in series with a vacuum gap, something I am reconsidering for
the new coil I almost completed this last summer.  I will not use the vacuum
gap on the newest coil.  I would be happy to e-mail some photo's of this
coil for your information if it might be of any interest.  Let me know.

You can go either high C low L or vice versa.  The current project is going
high C similar to what you seem to be leaning towards.  As long as you
accept the fact the your gap system will take a considerable amount of abuse
with a big cap, go for it.  Use 1/4" diameter moving electrodes, and 1/2"
fixed as a minimum.

Good Luck with your project.


-----Original Message-----
From:	Tesla List [mailto:tesla-at-pupman-dot-com]
Sent:	Wednesday, December 02, 1998 7:24 AM
To:	tesla-at-pupman-dot-com
Subject:	Big TC design

Original Poster: "Marco Denicolai"<Marco.Denicolai-at-tellabs.fi>

What I am wrestling with now is a rough design of secondary and primary

- secondary 15" wide by 60" high, 931 turns, 73 mH, 112/62 kHz
- toroid 10" section 60" outside diameter 62 pF
- primary spiral 18" inner diameter, 12 turns, 128 uH
- --> Primary capacitor must be 0.056 uF

I would like to maximize the capacitor size, to be able to pump more energy
into the primary. The problem is that, having a big secondary, I must have
a big primary inner diameter too. With just 12 turn of primary my capacitor
(required to be tuned) drops down to 0.056 uF. I would have liked at least
a 0.1 uF...One possibility is to use only 8 turns (--> Cap = 0.123 uF).

With 0.056 uF and 20 kV the cap energy would go up to 11.3 Joules, while
with 0.123 uF up to 24.6 Joules.

Any suggestions anybody?