Wire length,resonance, and Q (fwd)

To: "'Tesla List'" <tesla-at-pupman-dot-com>
Subject: Wire length,resonance, and Q (fwd)
From: Tesla List <tesla-at-stic-dot-net>
Date: Wed, 27 May 1998 00:24:41 -0500
Approved: tesla-at-stic-dot-net

----------
From:  Antonio Carlos M. de Queiroz [SMTP:acmq-at-compuland-dot-com.br]
Sent:  Tuesday, May 26, 1998 10:21 PM
To:  Tesla List
Subject:  Re: Wire length,resonance, and Q (fwd)

Barton B. Anderson wrote:

> However, for the
> secondary to yield it's highest voltage potential at the toroid (regardless of top C),
> there must be a 1/4 wave *situation* occurring in the circuit, even if it is not based
> entirely on the 1/4 wave wire length *situation*. I guess what I'm contemplating is if
> the 1/4 wave length of the P-freq. would correspond to the length of the secondary
> winding if the unknown variables were taken into account with the formula? I wish I
> knew just what all those variables were. Would't Vout be optimized?

The situation is quite simple:
The coil works as a transmission line, but if you measure its low-frequency inductance (L)
and the -first- resonance frequency (f) with one coil end open and the other grounded, you
can model the resulting circuit as a parallel LC resonant circuit, where the capacitance
("self-capacitance") is given by Cs=1/((2*pi*f)^2*L).
A toroid terminal, or other shape, acts as a grounded capacitance, with a capacitance (Ct)
that depends on size and shape.
This capacitance adds to the "self capacitance" of the coil, that is also grounded, and
the combination coil+terminal resonates at the frequency: f'=1/(2*pi*L*(Cs+Ct)).

Antonio Carlos M. de Queiroz