Cap charging

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

Original poster: "Luke" <Bluu-at-cox-dot-net> 

Can someone tell me if I have this right?

Let's assume a static gap and an NST of 15KV 60mA for this question.

If the gap is set to fire at 15KV the gap will fire at each peak of the 
cycle (120bps).
If the gap is set to fire at 20kv the cap will continue to charge until it 
reaches 20kv and then poof the gap fires.
Do I have a correct analogy for how this happens?
I think of it like the NST being a battery and the cap being another 
battery that will charge the cap.
So the NST will charge the cap to peak, then on the next cycle the NST's 
polarity will be opposite so the cap and NST can act like two batteries in 
series (like         + bat -  + bat - ) so now the NST will combine with 
the cap will produce more and the cap will store that charge.  This will 
continue with each cycle until enough voltage is built up to fire the gap. 
Is this correct so far?

Now if the gap is set to fire again at 20KV and the cap is of a small value 
so it charges up very quickly can the cap charge to the 20KV in one half of 
the ac cycle?  A post I found in the archives made it sound like it 
could.  This confuses me.  Because in only one half of the ac cycle we 
essentially have a dc voltage that is simply rising in value to a max.  and 
if dc is applied to a cap no matter how high the dc voltage is the cap will 
never reach a voltage over that.  So if in the case of a small cap that 
charges rapidly can reach say the 20kv in one half cycle of the 60hz cycle 
how does that happen?  If it cannot and it indeed does happen over 
successive cycles then I would like someone to at least let me know I am on 
the right track.





Luke Galyan
Bluu-at-cox-dot-net