Re: Measured value for various high voltage terminals

To: tesla-at-pupman-dot-com
Subject: Re: Measured value for various high voltage terminals
From: Tesla List <mod1-at-pupman-dot-com>
Date: Sat, 4 Oct 1997 13:43:48 -0600 (MDT)
Approved: mod1-at-poodle.pupman-dot-com


---------- Forwarded message ----------
Date: Fri, 3 Oct 1997 22:22:05 +0000
From: BertPool <Bert.Pool-at-flash-dot-net>
Reply-To: bertpool-at-flash-dot-net
To: Tesla List <tesla-at-pupman-dot-com>
Cc: bemery-at-swbell-dot-net
Subject: Re: Measured value for various high voltage terminals 

> Date:          Thu, 2 Oct 1997 21:51:20 -0600 (MDT)
> To:            tesla-at-pupman-dot-com
> Subject:       Measured value for various high voltage terminals 
> From:          Tesla List <tesla-at-pupman-dot-com>

> 
> 
> ---------- Forwarded message ----------
> Date: Thu, 2 Oct 1997 22:39:23 -0500
> From: "DR.RESONANCE" <DR.RESONANCE-at-next-wave-dot-net>
> To: Tesla List <tesla-at-pupman-dot-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-at-next-wave-dot-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-at-flash-dot-net