Re: topload questions

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Godfrey Loudner by way of Terry Fritz <teslalist-at-qwest-dot-net>" <ggreen-at-gwtc-dot-net>

Hello Antonio

I am getting the following:

16" x 7"------------19.2035 pF
16" x 1"------------13.9494 pF
16" x 0.1"----------9.87011 pF
16" x 0.01---------7.50278  pF
16" x 0.001"-------6.03675  pF

Let x = (D - d)/d. If x is large, then a good approximation to C is given
below.

C = 35.4 d (x^2 - 1)^(1/2) Q[-1/2, x]/P[-1/2, x], where C is in pF, D and d
in inches.

Q and P are the Legendre functions, commonly used in EE.

Godfrey Loudner





----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Saturday, January 25, 2003 5:08 PM
Subject: Re: topload questions


 > Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz
<teslalist-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>
 >
 > Tesla list wrote:

 > You apparently used an empirical formula to compute the capacitances.
 > I tried Fantc, that uses a precise numerical method, and got, for
 > the elements floating in space:
 >
 > 16"          sphere: 22.54 pF  (should be 22.60 pF)
 > 16" x 7"     toroid: 19.14 pF
 > 16" x 1"     toroid: 13.94 pF
 > 16" x 0.1"   toroid: 10.18 pF
 > 16" x 0.01"  toroid: 9.4 pF
 > 16" x 0.001" toroid: 9.3 pF
 > 16"          disk:   14.24 pF
 >
 > I am not sure about the precision of the calculations for the thin
 > toroids,
 > but they agree with what I can measure.
 > The "great part" is close to 50%, tending to 41% of the sphere
 > capacitance
 > for thin wire.
 >
 > Fantc takes forever to analyze the 16" x 0.001" case, and in all cases
 > lists a strange number as "exact value" (why?).
 >
 > Antonio Carlos M. de Queiroz
 >
 >