# Re: How to rise the secondary? (fwd)

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---------- Forwarded message ----------
Date: Wed, 8 Jul 1998 05:53:59 +0000
From: "John H. Couture" <couturejh-at-worldnet.att-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: How to rise the secondary? (fwd)

Bill, All-

The total secondary circuit capacitance (Cs) is equal to the sum of the
sec coil self capacitance and the capacitance of the toroid. The sec coil
self cap can be found using the Medhurst equation. The toroid cap can be
estimated using available sphere/toroid graphs. The approximate operating
frequency would be
F = 1/sqrt(LsCs) .   The inductance of the secondary coil (Ls) is found
using the Wheeler equation.

You are correct in saying that "the really tricky one is Cs". The Cs
includes the toroid cap which is changed to an unknown value when mounted on
the TC. However, the true Cs and toroid capacitances can be found after the
TC is built and tested to find the true operating frequency. You then vary
the toroid cap value in repeated manual calculations with the several
parameters involved until the test frequency shows up in the output. The new
total secondary capacitance (Cs) will be the true total capacitance. The new
toroid capacitance being used will be the true capacitance of the toroid
when mounted on the TC.

It should be noted that the above can be more easily done and the manual
calculations avoided by using that TC computer program that has occasionally
been mentioned on this Tesla List. This program has proven to be reliable in
designing Tesla coils.

John Couture

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At 04:47 PM 7/7/98 -0600, you wrote:
>
>
>---------- Forwarded message ----------
>Date: Tue, 07 Jul 1998 08:52:28 PDT
>From: Bill the arcstarter <arcstarter-at-hotmail-dot-com>
>To: tesla-at-pupman-dot-com, couturejh-at-worldnet.att-dot-net
>Subject: Re: How to rise the secondary?
>
>John Couture wrote:
>
>>  You build great coils so I am not going to tell you how to tune your
>>coils. However, a computer can tell you if the tuning equation
>>  LpCp = LsCs   is balanced. The tweeking can be done with taps
>>on the primary of a properly designed and tuned coil.
>
>I have questions regarding how these values are determined.
>
>Lp, Cp, are easily measured using any number of techniques.  But what
>
>Does Ls represent the "lumped' inductance of the secondary, measured (as
>above) between the base and top toroid?  I would bet this is the case
>but an not 100% sure.
>
>But the really tricky one is Cs.  The only way I can see to determine
>this is by measuring the actual self resonant frequency of the secondary
>and toroid using a sig gen, 'scope and all that.  Then - you compute Cs
>via the frequency and Ls.
>
>Any hints?  How are you folks determining these values?
>
>-Bill Pollack (arcstarter)
>
>______________________________________________________
>Get Your Private, Free Email at http://www.hotmail-dot-com
>
>

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