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# Re: Coupling Questions & coil measurements

```Robert Jones wrote:

> I good analogy of the system is two identical pendulums attached to the
> centre of a horizontal line but separated by a small distance.  If one
> pendulum is set swinging across the line, the amplitude of the other starts
> at zero then gradually increases as the amplitude of the first pendulum
> decreases to zero. Then the opposite happens.  The  energy repeatedly
> oscillates from one pendulum to the other.  The equivalent of quench is
> presumable when the first pendulum stops moving it is clamped and hence the
> second pendulum is forced to continue to swing.  I believe I saw this effect
> demonstrated on a OU program on UK TV.

The analogy is correct, but doesn't simulate the "change in impedance
level"
in a Tesla coil, with a low amplitude oscillation transferring energy to
a high amplitude oscillation. This can be approximately simulated with
two pendulums, one heavy and one light, tuned to the same frequency and
fixed to firm supports, but coupled by an inclinated light bar
connecting
the upper areas of the strings of the pendulums, higher in the light
pendulum and lower in the heavy pendulum (more about this in the
archives).

> How is the quench arranged to occur at the right time.

When there is low energy in the primary circuit, the gap cools, and with
some luck stops conducting.

> I have tried to derive the Laplace transform equations but it is tricky.
> Does some one have a Mathcad file with them in.  I have a Mathcad file some
> where that determines the best coil configuration for a high power RF tuned
> circuit.  I should be able to use some of the equation to define the Q of a
> Tesla primary and secondary.

I have posted the equations some time ago. Look in the archives, or
download my simulator from http://www.coe.ufrj.br/~acmq/teslasim.zip
All the equations are in the documentation.
The lossless case is much simpler, and exact analyses can be found in
some web sites and books.

Antonio Carlos M. de Queiroz

```