From: "Terrell W. Fritz"
Date: Mon, 25 Dec 2000 07:12:47 -0700
Subject: Re: [TSSP] Capacitance between primary and secondary
Hi Paul,
The primary and secondary coils were floating. There was no connection to
the ground plane. Just the two coils with the meter in between. So I
would think that would just leave the primary to secondary capacitance
only. Maybe others need to measure this too.
Cheers,
Terry
At 01:29 PM 12/25/2000 +0000, you wrote:
>Terry Fritz wrote (on tesla list):
>
>> I retook the physical measurements of my coil and measured the
>> capacitance from primary to secondary.
>>
>> I have the center of the primary plane 16.875 inches off the floor.
>> The inner primary radius is 5.95 inches.
>> There outer radius is 13.38 inches.
>> The primary tubing diameter is 0.252 inches.
>> There are 19.563 primary turns.
>> The secondary is still 10.25 x 30.0 inches.
>> There are 1000.5 turns
>> The secondary wire is 0.0201 inches in diameter.
>> The split 6 leg foil ground plane is on the floor but it is not connected
>> to anything.
>> The primary and secondary are floating.
>> My primary and secondary spiral (out and up) in the same direction.
>>
>> Pictures at:
>> http://hot-streamer.com/TeslaCoils/Temp/acmi1.jpg
>> http://hot-streamer.com/TeslaCoils/Temp/acmi2.jpg
>>
>> The primary to secondary capacitance measures:
>>
>> Height (inches) Capacitance (pF)
>> 0 42.2
>> 1 36.4
>> 2 33.7
>> 3 29.4
>> 4 27.6
>> 5 25.8
>> 6 23.6
>> 7 22.6
>> 8 21.8
>> 9 21.1
>> 10 19.8
>> 11 19.4
>> 12 19.0
>> 13 18.5
>> 14 18.0
>> 15 17.6
>
>Terry, I fed your dimensions into the new capacitance matrix
>generator, for the height 0 and height 15 cases.
>
>For height 0 I get the direct physical cap matrix elements:
>
> primary to groundplane: 24.0 pF
> primary to secondary: 26.7 pF
> secondary to groundplane: 22.5 pF all +/- 3%
>
>so the measurement between primary and groundplane will read
>the total capacitance as given by
>
> 26.7 | ( 22.5 # 24.0) = 26.7 | 11.6 = 38.3pF
>
>where | means 'in parallel with' and # means 'in series with'.
>I guess your presence in the field will have added a little more
>parasitic capacitance to bring the reading up to the measured value.
>
>The corresponding predictions for the 15" position are
>
> primary to groundplane: 27.1 pF
> primary to secondary: 5.9 pF
> secondary to groundplane: 28.2 pF all +/- 3%
>
>which gives a measurement of
>
> 5.9 | (27.1 # 28.2) = 19.7 pF,
>
>a little high of your 17.6 reading - not sure why.
>
>These capacitances are significant sizes and will have to be taken
>into account in the tssp simulator when primary coupling is
>introduced, although for acmi I should think they can be safely
>ignored.
>
>You might like to know that the new cap program generated the full
>distributed capacitance matrix for these two coil positions in a
>little under 15 minutes - quite an improvement in performance,
>which brings the prospect of being able to model a large number of
>coils that much closer.
>
>Cheers,
>--
>Paul Nicholson,
>Manchester, UK.
>--
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.