Re: Primary tank cap. value

["Tesla list" <tesla-at-pupman-dot-com>]

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

Hi Ted,

At 02:22 AM 7/6/2003 -0700, you wrote:
>I'm just starting to get involved with coiling and want to get my facts
>straight before I build a coil to avoid doing something stupid.  I've been a
>low-voltage electronics enthusiast for 3+ decades and was a Navy Electronics
>Technician in my youth (many years ago)

Cool!  You will know a lot more than most new coilers.


>My question is about setting the value of the tank capacitor in the primary
>circuit.  The various (very cool) automated calculators appear to take the
>apparent inductive reactance of the supply transformer secondary (e.g. 60ma
>-at- 12kv -at- 60Hz for a NST) and use it to set the capacitive reactance and then
>capacitance of the tank capacitor (based on TC-primary resonance).  Is this
>done to ensure maximum energy transfer from the supply transformer secondary
>into the TC-primary on each cycle of the main gap?

Yes, the reactance of the transformer and cap are the same at 60Hz and they 
are resonant there.  That is a bit bad since if the load is lost, the 
voltage will skyrocket and blow things up unless there are safety gaps and 
such.  LTR (Larger Than Resonant) cap sizes go beyond the resonant point 
until the voltage is brought back under control.  If there is a synchronous 
spark gap, then we can pull further power out by timing the gap carefully 
and getting power from the inductive kick effects and stored energy in the 
transformer's big secondary inductance.  A big chart is at:

http://hot-streamer-dot-com/temp/MMCcapSales.gif

Cheers,

         Terry




>Thanks,
>Ted Gill
>