# RE: Optimum toroid size

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Paul -

I did not intend to belittle your approach to finding a solution to the
optimum toroid problem. I was only trying to find some TC parameter that
could simplify the problem. The sphere had the unique chacteristics that
both the voltage breakout and the capacitance depended on the same variable,
the radius R. This made it easier to find the optimum size sphere for a
certain size Tesla coil. The toroid does not have this advantage so the
solution for optimum size will be more complicated. Any suggestions?

Your cubic equation is an excellent way to simplify the finding of the
R = cube rt(169 J) inches
Ctor = 2.8 R in picofarads

The sphere capacity can be found directly
Ctor = cube rt(3710 J) pf
J = input watts x eff
Ctop = Ctor + Ccoil

This gives the coiler enough information to find the TC operating frequency
and to design the primary circuit. The top terminal capacitance Ctor is one
of the inputs for the JHCTES Ver 3.1 Tesla coil computer program. Up to now
there has been little info on selecting this parameter. This parameter can
now be found using the above equation. The JHCTES Ver 3.1 program
coordinates and calculates 30 TC parameters and keeps them in tune.

In the past coilers have found that increasing the toroid size in tests
would increase the output spark. The problem was that there was no guidance
for finding the optimum size. The equation above can now be used to help in
the selection of the top load for any size Tesla coil.

John Couture

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-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Thursday, October 05, 2000 7:21 AM
To: tesla-at-pupman-dot-com
Subject: Optimum toroid size

Original poster: paul-at-abelian.demon.co.uk

My previous posting on this subject was intended merely to illustrate
the difficulty of finding a simple formula for the optimum toroid
size. If we're going to look at this further I should highlight, for
the record, a couple of assumptions that were made.

---------------------  snip

Regards,
--
Paul Nicholson,
Manchester, UK.
Secondary modeling project http://www.abelian.demon.co.uk/tssp/

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