Re: Lumped vs. Helical Resonator
Tesla List wrote:
> >From MSR7-at-PO.CWRU.EDUMon May 20 12:28:12 1996
> Date: Mon, 20 May 1996 08:10:01 -0400
> From: MSR7-at-PO.CWRU.EDU
> To: tesla-at-pupman-dot-com
> Subject: Re: Lumped vs. Helical Resonator
> Mark R. wrote:
> The interesting part of all of this to me is the influence the
> toroid has on the proximity effects near the top of the coil. This may be
> due to a change in the voltage standing wave along the secondary, resulting
> in a more linear voltage response, with reduced turn to turn proximity
> effects due to the similarity of voltage between adjacent turns. As one
> experiments with toroids of different sizes and positions above the top turn
> of the secondary, there is an optimal position whereby the secondary coil Q
> is maximized. This has been demonstrated by Malcolm in his experiments last
> year, and by Richard Hull on one of his video tapes. I have also observed
> this with my system, (but have too much metal nearby to get a quantitative
> Anyone have a good method for measuring high RF voltages?
> Mark S. Rzeszotarski, Ph.D.
Wow, this last question is the question of the century and something
numerous engineers and others have looked at for years. Naturally, spark
length is not only a qualitative but also a quantitative measure of RF
voltage. But, and that is a big but, only if every parameter in any
comparison is held fixed! This could only be done in a controled
temperature/humidity lab with fixed frequencies, duty cycles,
Toroidial loadings, etc. Even with this situation, I don't honestly
believe that the results of any measurements would be absolutes but only
We have tried numerous schemes and methods, all have left us uneasy about
presenting them in our videos or even in a casual paper on the subject!
One area that holds some promise, but still is open to debate, came about
with our discovery and utilization of static DC charges collected in air
on isolated isotropic capacities in and around operating tesla coils.
This is an analog of the electric field density of charge put out by a
given coil. Unfortunately, it is probably a better indicator of power
conversion efficiency than actual voltage produced and relates heavily to
the type of terminal and the manner of air discharge.
We are trying to develop a fixed form of discharger to allow at least a
method of comparision between systems using rather simple
instrumentation. Still, the actual RMS RF voltage appearing on the
terminal is almost impossible to know as an absolute.
The closest approach we have thought of, intellectually, would be the
instant of break out related to the shape and dimensions of a smooth
sphere with DC potentials. Basically, a tesla coil, until it breaks out
of such a sphere, would theoretically be on a DC footing and work could
proceed along these lines. The requirement for a huge number of
graduated, large spheres, however, would be prohibitive.
Basically, Mark, after about 6 years on this question, we are not on a
firm footing to put forth a definitive answer to your question,
especially as regards giant systems.
Richard hULL, TCBOR