# Re: Tesla turns ratio ?

```Subject:      Re: Tesla turns ratio ?
Date:   Thu, 12 Jun 1997 21:05:39 -0800
From:   Greg Leyh <lod-at-pacbell-dot-net>
To:   Tesla List <tesla-at-pupman-dot-com>
References:  1

Alfred A. Skrocki wrote:

> Owen, you are correct when you say the number of turns effect the
> inductance of a coil and as such one should strive to get as any
> turns on the secondary as is practical. BUT the actual turn count is
> irrelevant because the ratio of transformation in a Tesla coil IS NOT
> related to the ratio of primary to secondary turns! For the benefit
> of anyone who is not familiar with the derevation of the ratio of
> trasformation in a Tesla coil here it is:
>
>               E = .5 x C x V^2  :energy stored in a capacitor
>          Eprimary = Esecondary  :conservation of energy law

[snip]
>
> Solving in terms of Vsecondary gives;
>
>                   Vsecondary = SQRT (Cprimary / Csecondary)

Alfred has captured here the essence of the TC in a nutshell!

The above equation _alone_ must necessarily determine the maximum
possible
output voltage of any given TC or magnifier. It is often revealing to
apply this equation to Tesla coils, especially when the advertised
output
voltage is over 5 million volts.

It is important to note from the above equation that changing the
inductance
of the sec. _does not_ affect the output voltage, if the sec.
capacitance
is held constant.

So why is the sec. inductance of any importance then?   Arc size!

If the objective is simply to maximize arc size then the TC designers'
goal
is not to maximize Vsec, but rather to match the effective _impedance_
of
the arcs to the impedance of the wall outlet, so that maximum power can
be
dumped into the ionized air.

The sec. inductance should then be selected so that the surge impedance
of
the secondary falls somewhere within the realm of the output arc
impedance,
if the coil is to be an efficient 'air incinerator'.

-GL

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