RE: Tesla Coil Blunders

["Tesla list" <tesla-at-pupman-dot-com>]

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


Malcolm -

When I mentioned coilers I was thinking of all coilers including myself and
I did not mean to insinuate incompetence. I believe that coilers may be
ignoring the very important resonant frequency equation and the R term that
is vital in describing how a Tesla coil operates. It may be a big mistake
not to explore the R in this equation during TC operation. This can be done
by determining the operating resonant frequency and comparing it with the
Wheeler/Medhurst/ resonant frequency. In the past any change in resonant
frequency may have gone unnoticed because the tests were not accurate
enough.

It is interesting that this resonant frequency reduction due to the size of
the R is not mentioned in electrical or radio publications except the Tesla
Coil Construction Guide. One reason may be that with radio transmitters the
R in the output (radiation) is always low enough to have only a negliable
effect on the resonant frequency. However, this is not true of Tesla coils
which produce much higher voltages and have high resistance and current
outputs.

I think you can forget the R in the Q factor equation because this resonant
frequency R is not the same. This R has to do with the secondary output and
cannot be measured during TC operation. However, it can be easily calculated
when the reduced resonant frequency is known. This R would also be handy in
finding the secondary voltage by Ohm's Law because the current in the
secondary can be measured during TC operation.

It will require many unique tests by coilers in the future to find the R's
of various coils and to develop a graph for TC design.

John Couture

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

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Sunday, April 08, 2001 2:54 PM
To: tesla-at-pupman-dot-com
Subject: RE: Tesla Coil Blunders


Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<m.j.watts-at-massey.ac.nz>

John,
        I think words such as blundering are close to insinuating
incompetence and I for one, take objection.The figures I plugged into
your equation were entirely reasonable and taken from a coil that
works. Check your maths - there is an error in it.

On 6 Apr 01, at 12:19, Tesla list wrote:

> Original poster: "John H. Couture by way of Terry Fritz
> <twftesla-at-uswest-dot-net>" <couturejh-at-worldnet.att-dot-net>
>
>
> Malcolm -
>
> It appears the resonant frequency equation is beginning to reveal some
> of it's secrets. Most coilers take this equation for granted not
> realizing that it has some interesting properties for the Tesla coil.
> One of those properties is that if the R is large enough you will end
> up with a square root of a negative number. As I say in the TCC Guide
> that shows this equation when the R is large enough there will be no
> resonant frequency. This would probably never occur with TC operation,
> however, some R value is always present in the TC system when
> operating. The R is normally small enough and can be ignored with
> signal generator low power tests. But how about the R when the TC is
> operational? Are coilers blundering in this matter.
>
> With the operational secondary circuit the R includes all losses plus
> the load. The load during operation includes streamers, corona,
> radiation, etc. It is obvious that the load can present a large
> variety of conditions during operation. Researching these conditions
> could help obtain better output from the TC system. One exception is
> when sparks to ground occur which is a direct shorting of the
> secondary circuit to ground. This means that tests would be made only
> with (small streamers?) and not strikes to ground.
>
> For the above to have any significance the following question must be
> answered. Does the resonant frequency reduce when the TC is
> operational compared to the low power signal generator measurements?
> If it does how does it affect the R of the resonant frquency equation?

Chicken or egg? Which? Are you saying a drop in frequency affects R
or that R effects a drop in frequency? Be absolutely clear what you
are saying. R does not increase if there is no output discharge of
any sort. In fact, it is liable to decrease in the ground path. The
loaded Q of 10 I gave incorporates attached streamer loading and is a
typical figure measured by myself and others.

> These are difficult tests to make with resonable precision (+/- 1%?)
> and maybe standard test methods should be set up so the test results
> are more coordinated. In the past the few tests of this type that have
> been made have given conflicting results.
>
> John Couture

All I can say is that appeals to mysticism and disregard for that
which you do not understand has no place in scientific enquiry. Sorry
to be so pointed but you threw the gaulntlet down.

Malcolm