Re: Tesla's Radio Circuit (fwd)

---------- Forwarded message ----------
Date: Fri, 24 Jul 1998 13:12:47 -0400
From: Dan Kline <ntesla-at-ntesla.csd.sc.edu>
To: tesla-at-pupman-dot-com
Subject: Re: Tesla's Radio Circuit

>---------- Forwarded message ----------
>Date: Thu, 23 Jul 1998 05:13:18 +0000
>From: "John H. Couture" <couturejh-at-worldnet.att-dot-net>
>To: Tesla List <tesla-at-pupman-dot-com>
>Subject: Re: Tesla's Radio Circuit (was tuning more accurately than 5%)
>  I disagree about Tesla having "honed what was first just a glorified
>induction coil system". 


At the risk of being flamed to death as a heretic (geez, I *hate* to do
*sigh*) My personal research has revealed that it's quite probable that
Tesla got the idea of the air-core coil after seeing a demonstration of
exactly that very thing by, I think it was, Elihu Thompson, in the late

I actually have a copy of the original lecture wherein Thompson reveals the
specifications of the coil he demonstrated. It was built *like* an
induction coil, except that the primary was on the outside and the
secondary was on the inside. However, the coaxial construction was the same
as an induction coil and the coils were oil immersed. He doesn't give his
primary capacitance so there's no way to know if the coil was tuned, but
I'd suppose that it would have had to have been, since it operated by
*disruptive discharge,* rather than mechanical interruption like a
conventional induction coil.

Thompson's point of the whole thing was that great discharges could be
produced without the incredible lengths of wire necessary to build giant
induction coils. He presented the information as though his idea was a
great innovation. Thompson's coil put out a 60" discharge between the

If I had the coil Thompson describes, and took it out of the oil, and made
the primary coil so that it *wasn't* stretched the entire length of the
secondary coil, I'd have a classic air-core bi-polar Tesla-coil.

Also, one of Thompson's biographers claims that Thompson took the credit
for having given Tesla his start. We know that's probably nonsense since
Tesla was already way "started" before he ever got to America ;) However,
it does fill in the gap concerning the iron-core--->air-core years...

Tesla was already creating tuned induction coils at that time, so tuning
and resonance were not unknown concepts. I'll find the exact dates of all
this if anyone is really interested, but geez, go light on the flames, ok?
I really get depressed over being apprehensive about opening my mail...:/

Regards :)

Dan Kline
Information Resource Consultant I
USC-Computer Services