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Re: Measured value for various high voltage terminals
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To: tesla@pupman.com
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Subject: Re: Measured value for various high voltage terminals
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From: Tesla List <mod1@pupman.com>
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Date: Sat, 4 Oct 1997 13:43:48 -0600 (MDT)
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Approved: mod1@poodle.pupman.com
---------- Forwarded message ----------
Date: Fri, 3 Oct 1997 22:22:05 +0000
From: BertPool <Bert.Pool@flash.net>
Reply-To: bertpool@flash.net
To: Tesla List <tesla@pupman.com>
Cc: bemery@swbell.net
Subject: Re: Measured value for various high voltage terminals
> Date: Thu, 2 Oct 1997 21:51:20 -0600 (MDT)
> To: tesla@pupman.com
> Subject: Measured value for various high voltage terminals
> From: Tesla List <tesla@pupman.com>
>
>
> ---------- Forwarded message ----------
> Date: Thu, 2 Oct 1997 22:39:23 -0500
> From: "DR.RESONANCE" <DR.RESONANCE@next-wave.net>
> To: Tesla List <tesla@pupman.com>
> Subject: Measured value for various high voltage terminals
>
> To: Tesla List
>
> One day last month we got ambitious and set a number of various size high
> voltage terminals high atop an insulated column and then measured their
> capacitance. Thought these values might be of interest to TC builders in
> the group:
>
> 7 inch dia sphere - - - - - - - - - 14 pF
>
> 14 inch dia sphere - - - - - - - - 22 pF
>
> 30 inch dia sphere - - - - - - - - 44 pF
>
> 40 inch dia sphere - - - - - - - - 60 pF
>
> 1 3/4 x 7 inch toroid - - - - - - - 9 pF
>
> 8 x 3 toroid - - - - - - - - - - - - - 11 pF
>
> 12 x 3 toroid - - - - - - - - - - - - 16 pF
>
> 14 x 4 toroid - - - - - - - - - - - - 25 pF
>
> 24 x 6 toroid - - - - - - - - - - - - 38 pF
>
> 34 x 8 1/2 toroid - - - - - - - - - 50 pF
>
> 48 x 12 toroid - - - - - - - - - - - 67 pF
>
> "Average" electric field capacitance for small oscillator with 6-14 inch
> spark is approx 7.5 pF
>
> "Average" electric field capacitance for med oscillator with 14-30 inch
> spark is approx 20 pF
>
> "Average" electric field capacitance for large oscillator with 3-9 ft spark
> is 35-50 pF (at 5-7 kva)
>
> These values do not include the self "distributed" capacitance of the
> secondary inductor and do include the capacitance of the high voltage
> terminal. Terminal values are listed above and self capacitance can easily
> be determined by measuring the inductance and resonant freq of the
> inductor. From these two measured values the capacitance can be determined
> with simple algebra. The terminal capacitance and electric field
> capacitance can be added to these values by taking a snapshot (best to take
> about 2 dozen) of a normal scope with antenna pickup set at a distance from
> the coil while it is running and in tune. The resonant freq is then
> measured directly from the scope snapshot by knowing the sweep speed of the
> scope setting and a bit of math. The freq is equal = Fr = 1/t where t is
> the period of the oscillation. When the actual operating freq is found
> then the difference in frequencies and the known measured inductance is
> used to find the change in the value of capacitance. Already knowing the
> capacitance of your high voltage terminal you can now subtract the
> capacitance difference between the two values. The remaining value is the
> capacitance of your electric field above the coil while it is running.
> This value is important because it can be scaled up to assist in the design
> of future coils.
>
> DR.RESONANCE@next-wave.net
>
>
>
>
>
Thank you for posting this - Wild Bill and I were just discussing
what the possible capacitance values of the field on a coil might be,
so this was a very timely post for us.
Bert Pool
TCBFW
bertpool@flash.net