Re: True Toroid Capacitance

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

Original poster: "Dr. Resonance" <resonance-at-jvlnet-dot-com> 


It runs close to 10-14% for a "normal" modern coil with a toroid dia. to sec
coil dia. ratio of 2:1.  If you place a 36 inch toroid on a 4 inch coil then
it's another matter entirely.

With the 2:1 normal size a 10% deduction seems to be a stable value.

Dr. Resonance

Resonance Research Corporation
E11870 Shadylane Rd.
Baraboo   WI   53913
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Thursday, November 06, 2003 5:21 PM
Subject: RE: True Toroid Capacitance


 > Original poster: "John H. Couture" <couturejh-at-mgte-dot-com>
 >
 >
 > Malcolm -
 >
 > I agree that using a fixed percentage of toroid reduction does not appear
to
 > be realistic. The wide range of true toroid capacities for the same toroid
 > requires testing each TC for the resonant frequency after it is built.
This
 > resonant frequency will give you the true toroid capacitance in the JHCTES
 > Ver 3.42 TC program and will always be less than the theoretical
 > capacitance. The accuracy of the toroid capacitance will depend only on
how
 > well you do the test and enter the inputs, no assumptions will have to be
 > made.
 >
 > Your experiment with the 8" major dia toroid is the perfect demonstration
to
 > show the dramatic behavior of the toroid capacitance when in the real
world
 > of Tesla coils. As you indicate the  capacitance was less than one pf when
 > placed on the 17" coil. This indicated a very large capacitance reduction
of
 > about 90% from the theoretical capacitance! In the test where this 8"
toroid
 > was placed on the 2" coil and showed a significant difference (larger
 > capacitance?) this would indicate a very small reduction from the
 > theoretical capacitance. It is obvious that the same toroid can have a
wide
 > range of capacitance reduction from the theoretical capacitance. In your
 > tests the range was about 10% to 90% toroid capacitance reduction!
 >
 > The es fields around the TC, toroid, and including surrounding effects are
 > very complicated and to make calculations work assumptions have to be
made.
 > However, the accuracies using these calculations in programs appear to be
 > acceptable. Because the frequency test takes everything into consideration
 > it can then be used to verify the accuracy of the programs after the TC is
 > built.
 >
 > Using the resonant frequency test to verify the true toroid capacitance
 > reduction is relatively new and there is very little  data available to
 > compare the TC computer programs with the results of the tests. Hopefully
 > more coilers will make these tests in the near future.
 >
 > John Couture
 >
 > -------------------------------------
 >
 > -----Original Message-----
 > From: Tesla list [mailto:tesla-at-pupman-dot-com]
 > Sent: Wednesday, November 05, 2003 10:17 PM
 > To: tesla-at-pupman-dot-com
 > Subject: RE:True Toroid Capacitance
 >
 >
 > Original poster: "Malcolm Watts" <m.j.watts-at-massey.ac.nz>
 >
 > Hi John,
 >            I'd like to add a comment to your piece based on my own
 > experimentation. We have seen, from various sources, a percentage
 > reduction figure in Ctor when placed above a coil to account for the
 > disparity. But the problem is not that simple. Some time ago I
 > checked some extremes to determine the mechanisms involved. The most
 > radical of these was to pop a 8" (major) diameter toroid on top of a
 > 17" diameter coil. The capacitance added was less than a pF
 > (according to the change in Fr) yet the same terminal caused a very
 > significant difference when placed above a 2" diameter coil (don't
 > ask me to quantify it - it was so long ago I forget the figures).
 > However, the 2" case was in the 10%-type range, in other words, more
 > than notable. Point is, a fixed reduction percentage figure will
 > apply only for a limited set of size - size ratios and is therefore
 > invalid in general. However, I see no reason why a figure for a
 > particular coil and torus cannot be calculated with a modicum of
 > precision based on a consideration of e.s. fields and possibly even
 > just a mechanical size vs size rule (including of course pacement
 > height of the toroid above the windings).
 >
 > Malcolm
 >
 > ----------------------   big snip
 >
 >
 >