# RE: TC Coupling & Mutual Inductance

```Original poster: "John H. Couture by way of Terry Fritz <twftesla-at-uswest-dot-net>" <couturejh-at-worldnet.att-dot-net>

Peter -

Just find total secondary capacity and subtract coil self capacity. I can
send you a copy of my report.

John Couture

-----------------------------

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Friday, December 22, 2000 5:05 PM
To: tesla-at-pupman-dot-com
Subject: Re: TC Coupling & Mutual Inductance

Original poster: "Peter Lawrence by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <Peter.Lawrence-at-Eng.Sun-dot-com>

John Couture,
I've always wondered how to mathematically combine the Cself
of a secondary with the C of a torroid, each of these can be calculated
independently by well known formulas, but then do they simply add, or is
it like a series cap 1/(1/Cself + 1/Ctorr), or something else totally
different because of interference between the torroid and the coil
windings...

-Pete Lawrence.

>The report shows schematics for testing several TC parameters including
>coupling, total secondary capacitance, operating frequency, etc. It also
>shows how to determine the actual capacitance of the toroid when it is on
>the secondary. The mutual inductance is found by
...
>John Couture
>10823 New Salem Point
>San Diego, CA 92126

(PS,

Cself,pF  = 0.29 * H + 0.41 * R + 1.94 * sqrt(R^3 / H);  Height, Radius
inches

Ctorr,pF = 1.4 * (1.2781 - d/D) * sqrt(PI * d * (D - d));  Diam, diam
inches
)

```