Re: Early TC's w/o topload

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: wysock@xxxxxxx 

Hello to Frank, Matt, and all,
and, Happy New Year.

Of course, Tesla shows a toroid in his famous patient that everyone has seen.
The closest he came to using one himself was at Colorado Springs, as a
"hood" above his extra coil.  At Wardenclyffe, he used more the form of
what is referred to as an "obleat" meaning more of a mushroom shape,
on top of his 168 foot tall tower.

I had one of these "obleats" from an old Morris and Lee 500 KV Van de
Graaff generator kit that I had purchased and built in 1962.  When I was
developing my (original) line of Tesla Coils, I experimented with this form
of electrode on a medium-size coil.  From my readings and experiments
in electrostatics, I could see first hand, the advantages of this form of
electrode for the secondary coil.  Then I remembered other lessons
learned from days of experimentation in electrostatics.  From old
magazine archives, I recalled that a French physist named Farrante
had also developed a form of electrode that was similar to today's
"toroid".  He used a wire cage form in the shape of a toroid, to control
high voltage corona leakage, on a 1,000,000 volt cascade low
frequency transformer exhibit, that was shown in Paris at a World's
Fair.  There was a picture of him holding this device (almost as tall as
he was).

The Morris and Lee obleat I was using in early 1974 was made of
aluminum, and had an equitorial diameter of about 14 inches with a
height of about 6 inches.  It worked much better then the small copper
ball I had (previously) used, but still, didn't totally eliminate corona
leakage from the top-most turns of the secondary coil.  So I bought
a commercially-made 20 inch diameter toroid that had a 5 inch cross-
section.  This toroid is really represented as 'C3' in the resonant circuit
with 'C2' being the self-capacitence of the secondary coil itself, and
'C1' being the primary circuit resonant tank capacitor.

The rest is history.  This coil became my first (commercially) introduced
coil to the market...Model 5.  That was January, 1975.  The Model 5 coil
would produce spark lengths more then 3 times the (physical) winding
length of the coil form (about 55 inches with 2.5 KVa input power).  This
(early) form of the Model 5 coil used my own design of a multi-segment
true quecnhed spark gap in the primary circuit.

Nowadays, everyone uses a "toroid" as a "topload" on their coil(s).  I
believe the term "topload" is credited to the good folks on this Tesla
List.  In the (earlier) days of Harry Goldman's TCBA newsletter, one
never saw the term "topload" in print.

Best regards,
Bill Wysock.

Date sent:      	Tue, 03 Jan 2006 16:13:40 -0700
To:             	tesla@xxxxxxxxxx
From:           	"Tesla list" <tesla@xxxxxxxxxx>
Subject:        	Re: Early TC's w/o topload
Forwarded by:   	tesla@xxxxxxxxxx
Date forwarded: 	Tue,  3 Jan 2006 16:10:05 -0700 (MST)

> Original poster: Mddeming@xxxxxxx
>
> In a message dated 1/3/06 1:27:22 P.M. Eastern Standard Time,
> tesla@xxxxxxxxxx writes:
> Original poster: "Angelini, Frank J" <FrankJAngelini@xxxxxxxxx>
>
>
> Most of the TC's I've built over the years were based on articles in
> old magazines
> from the 1920,s and 30's.  They seldom used any topload, but rather
> had a discharge
> terminal alone or one with a small discharge ball.  I wondered
> why?  Was this due to a
> basic lack of knowledge concerning the benefit of a sphere or
> toroid?  Did Tesla use
> a designed topload?
>
> Thanks,
>
> FJA
>
>
> Hi Frank,
>
>      At that time, producing the longest sparks was not the main
> purpose of Tesla coils. They still had practical HV/Xray/research
> uses for which the sparks were counter-productive.
>
> Matt D.
>
>
>

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