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RE: Primary and Secondary winding direction



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


Paul -

I read about this optimum toroid many years ago but I do not remember where.
However, I do not believe it is a myth because this design method will give
a workable TC. It actually gives a secondary topload capacitance which may
or may not be an optimum. It also gives a capacitance that agrees with the
intersection of the two curve graph we discussed last October.

It appears, however, that the optimum refers only to a sphere topload. An
optimum toroid for a Tesla coil may be an impossibility because the ROC of
the minor diameter of the toroid will always be too small to prevent
breakout of the spark. This is probably why you found the optimum toroid
came out to be similar to a doughnut without a hole in it.

This design method is only a way to solve for two unknowns using two
equations. One of the equations is the frequency equation and the other is
the 1/4 wavelength equation. If the secondary is made smaller the wire
length will be shorter, the frequency will be greater, and the capacitance
will be smaller according to the equations. The opposite will happen if the
secondary is made larger.

I agree this method for a toroid is on shaky ground for optimizing a TC
secondary topload. However, it does agree with the graph method which is an
optimized performance method for a sphere.

Am I taking too much for granted?

John Couture

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


-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Sunday, January 07, 2001 2:14 PM
To: tesla-at-pupman-dot-com
Subject: Re: Primary and Secondary winding direction


Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<paul-at-abelian.demon.co.uk>

John Couture wrote:

> Tesla was interested in the 1/4 wavelength secondary and used it to
> find the optimum toroid (secondary terminal) of a Tesla coil.You can
> find more info by going to my web site and checking on
> "6. Optimum Toroid".

John,

I took a look at your web page page, and if I understand correctly you
are suggesting that the toroid should be chosen to bring the resonant
frequency down to that of the quarter wave resonant frequency of the
wire length which was used to wind the secondary.

Perhaps you could justify this a little more, in view of the fact that
when the coil is wound, the inductances and capacitances which
determine the wire's resonant frequency are completely disrupted from
their straight line values as a result of winding, and thus the
original straight line resonant frequency of the wire seems to be of
historical interest only. I fail to see how it can have sufficient
relevance to warrant its use as a basis for toroid selection when in
view of energy storage the smallest possible toroid ought to be
desirable. In what sense is the performance optimised - not for output
voltage, obviously - and which performance measures deteriorate when
the toroid is increased or decreased from this optimum size?

Hopefully you can help me out on these points, otherwise I can only
label this notion as another of those Tesla myths since is doesn't
seem to have a sound basis. Could it be that Tesla used this idea at
one time as a working hypothesis, in the absence of anything better,
and never got the opportunity to refute it?

Regards,
--
Paul Nicholson,
Manchester, UK.
--