# Re: Secondary capacitance

```Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Frederick,

Vs = 0.7(Vp * SQRT(Cp/Cs))

will be pretty darn close!  About 1/2 the coil's power is lost in the gap
which this takes into account.  For a simple equation, this is as good as
it gets.  You may be interested in:

http://hot-streamer-dot-com/TeslaCoils/MyPapers/modact/modact.html

For secondary capacitance, see this program and included notes and text
files...

http://hot-streamer-dot-com/TeslaCoils/Programs/E-Tesla6.zip

Cheers,

Terry

At 12:16 AM 5/22/2002 +0200, you wrote:
>
>Hello all,
>
>I'm trying to calculate the peak secondary voltage using this formula:
>
>Vs = Vp * SQRT(Cp/Cs)
>
>Vs = peak secondary voltage
>Vp = peak charge voltage of tank cap
>
>How do I find out the secondary capacitance (Ctot = Csec+Cterm)?
>Or more exact, how do I calculate Csec (sec. coil capacitance)?
>Using Bert Pool's formula for toroid capacitance, I calculated a Cterm
>value of 2,503 pF.
>Is the capacitance of the secondary coil significant?
>
>Using the first mentioned formula, my 8kV input and my 0,01 uF tank cap
>gives about 715 kV peak secondary voltage which (even under ideal
>conditions) seems a little high for my small coil.
>
>I wouldn't know what to "expect" from my coil. Here are the specs:
>
>Dual 4kV parallel NSTs phased for 8kV
>0.01 uF MMC
>Single static gap
>Flat primary tapped at about 5½ turns
>1200 turns secondary, 0.3 m high
>6.5" by 1.8" toroid
>
>Sincerely,
>Fredrik Holmström
>

```