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Re: Tesla Coil toroid Size
Malcolm -
Thank you for the toroid capacitance data from your measurements. I
thought you would be interested in what I caculated. The following
information is based on methods that have not been completely verified.
The "In space" capacitances are from theoretical equations. I show a
graph in one of my books based on these equations. The "On TC" capacitances
are estimated for your toroid but based on what I have found from other
coilers tests. Note that the toroid capacitance is reduced by the presence
of the coil.
In space On TC
Toroid #1 - 11 x 30 33 pf 26 pf
Toroid #2 - 10 x 23 28 pf 22 pf
Toroid #3 - 6 x 19 22 pf 17 pf
I would expect differences from your values because the tests differed.
The above results (On TC) would be obtained by finding the actual operating
frequency of the TC and using this info to find the effective capacitance
of the toroid.
Cs = 1/(39.5 Ls F^2) and Ctor = Cs - Ccoil
John Couture
---------------------------------------
At 07:50 PM 9/8/98 -0600, you wrote:
>Original Poster: "Malcolm Watts" <MALCOLM-at-directorate.wnp.ac.nz>
>
>Yesterday I wrote:
>
><snip>
>> Here are some figures for some different coils I have measured.
>> These figures are not the last word because isolation was not as
>> great as I would have liked for definitive measurements, but here
>> goes:
>>
>> Terminal 1 (fairly large, toroidal profile, no centre hole)
>> Terminal 2 (smaller, same shape)
>> Terminal 3 (much smaller, same shape)
>>
>> Dsec Hsec Csec Cterm1 Cterm2 Cterm3
>>
>> 3.5" 14" 6.4pF 39.4pF 29.3pF 18.5pF
>> 4.4" 17.2" 7.9pF 36.2pF 26.6pF 16.2pF
>> 4.8" 21.8" 9.4pF 31.6pF 22.7pF 13.4pF
>> 6" 22.7" 10.7pF 33.3pF 23.8pF 13.8pF
>> 6.7" 12.1" 8.4pF 40.2pF 29.7pF 18.4pF
>> 6.7" 19.8" 10.3pF 38.4pF 27.9pF 16.9pF
>> 6.7" 32.3" 13.5pF 34.1pF 24.2pF 13.8pF
>> 9" 16.1" 11.2pF 31.7pF 22.8pF 13.6pF
>> 16.7" 39" 22.9pF 30.1pF 21pF 11.9pF
>
><snip>
>
>Terminal sizes are:
>
>#1 : 11" high (thick), 30" diameter
>#2 : 10" " , 23" "
>#3 : 6" " , 19" "
>
>As far as I've been able to ascertain through other measurements, the
>fact that there is no hole in the "donut" does not significantly
>alter capacitance. Imagine e-field lines stretching from the various
>parts of the terminals to ground and you might see a reason why a
>filled-in top doesn't make a difference. For the meaurements above,
>the terminals were all at roughly the same distance from floor/roof
>of the garage so the resonators were mounted at different heights.
>
>Malcolm
>
>
>