Modeling a magnifier

To: "'Tesla List'" <tesla-at-pupman-dot-com>
Subject: Modeling a magnifier
From: Tesla List <tesla-at-stic-dot-net>
Date: Sun, 22 Feb 1998 23:52:23 -0600
Approved: tesla-at-stic-dot-net

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From:  John H. Couture [SMTP:couturejh-at-worldnet.att-dot-net]
Sent:  Sunday, February 22, 1998 7:16 PM
To:  Tesla List
Subject:  Re: Modeling a magnifier

  Antonio, All -

  Your desire to model a Tesla magnifier is admirable and I wish you
success. I found that modeling the classical TC to use for the JHCTES
computer program was a very difficult job. In fact it is impossible without
realizing that the "Tesla coil design is empirical". The quotation is from
my EE Handbook and I can now appreciate what that means. It means that
modeling a TC requires both theoretical and practical knowledge (data from a
lot of actual tests).

  The most important theoretical advantage of the TC magnifier is that the
third coil may have less losses and, therefore, produce higher secondary
voltage compared to the classical TC for the same energy input. There are
supposed to be less losses because the third coil is out of the influence of
the primary inductive field.

  Your problem in making a model for the magnifier is to determine if these
reduced losses actually exist. This requires comparison tests of actual
classical and magnifier coils using the same input energy conditions. To my
knowledge, no one has ever done these tests for any magnifiers.

  Note that the K factor has little to do with producing a higher secondary
voltage in the magnifier compared to the classical coil (K and Vs are not in
the same equations).  Finding the K factor is not as important as the
solutions for the input and output energy and losses in the system. The
proper modeling of these parameters is very important to keep within the
limits of the energy conservation law. Too much voltage gain could mean over
unity energy. Once these parameters are determined the secondary voltage can
be easily found by the  equation    Vs = sqrt(2 x Js/Cs)     where Js is the
energy in the secondary circuit and Cs is the total sec capacitance.

  Tesla said the resonant frequency should be the same for all three coils
for optimum output. This means that these equations should be satisfied   
          L1 C1 = L2 C2 = L3 C3
However, as long as the pri and sec circuits are in resonance but the third
coil is not in resonance there would still be a good output from the system
provided you have enough KW input. This means that you could have a small
third coil giving a very impressive "spark length to third coil length
ratio". Some coilers have already noted this fact.

  The spark timing and duration will be different for the magnifier than for
the classical coil. Modeling the conditions for proper spark would be the
easiest part of the job because there are less parameters. However, proper
spark timing and duration would be difficult to accomplish with real coils.
This is where most of the losses occur so a proper model would be very
important.

   John Couture

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At 04:26 PM 2/21/98 -0600, you wrote:
>
>----------
>From:  Antonio Carlos M. de Queiroz [SMTP:acmq-at-compuland-dot-com.br]
>Sent:  Friday, February 20, 1998 4:41 PM
>To:  Tesla List
>Subject:  Modeling a magnifier
>
>Hi:
>
>I was studying how to model a Tesla magnifier, and would like to hear
>comments on my reasoning:

-------------------------------------   big snip

>The advantages of the magnifier are that the high voltage terminal can
>be moved away from the primary circuit, and that a more compact and predictable
>primary circuit can be used.

>What do you think?
>
>Antonio Carlos M. de Queiroz
>http://www.coe.ufrj.br/~acmq