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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
>
>
>