Re: True Toroid Capacitance

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

Original poster: Peter Lawrence <Peter.Lawrence-at-Sun.COM> 

Dr Res,
        most of your posts concerning ratios are confusing, since every toroid
has two diameters (and there are two different commonly used ways to measure
the larger one, center-to-center and outside to outside)), and the secondary
has two measurements (length and diameter).

In your recent post you might be saying the toroid minor diameter should be
approx twice the secondary diameter, but I'm not sure. You don't say what
the toroid major diameter should be (for a "normal" modern coil).

In my own TCs my toroid minor diameter is slightly less than my secondary
diameter, and my toroid major diameter (measured outside-to-outside) is
slightly less than my secondary length. I have tried slightly larger
toroids without much improvement in streamers, but thats probably because
I'm input power limited.

-Pete Lawrence.



 >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
 > >
 > >
 > >
 >
 >