Re: capacitor sizing (was 60 vs 30 ma)

From: 	William Noble[SMTP:William_B_Noble-at-msn-dot-com]
Sent: 	Friday, June 20, 1997 5:30 PM
To: 	Tesla List
Subject: 	capacitor sizing (was 60 vs 30 ma)

I do not agree with the analysis below .  while true that an ideal cap driven  

by an ideal voltage source has current proportional to dv/dt, this isn't the 
case in a real circut.  moreove, I understand that neons are current limited.  

The current into the capacitor is the cosine of the phase angle, so it's a max 

at 0deg (where the voltage revrses)  If the ideal current here is large, say 1 

amp, then a 30 ma transformer will put in less charge than a 60 ma transformer 

because both will be in current limit. 

snip [Bill]  -------------------------- 
> It would seem to me that if one switches to a transformer with
> twice the current rating, using the same capacitor, that the
> capacitor would simply charge up to the spark gap voltage twice
> as fast.

You can make all the current in the world available to a capacitor 
and it is NOT going to charge any faster! To make a capacitor charge
faster you have to increase the applied voltage! Try and remember the
old analogies to clearify; current is the quantity of electrons and
voltage is the pressure the electrons are under. How any electrons 
you have available wont effect how fast a capacitor charges, but the 
amount of pressure (voltage) they are under will! If you keep the 
applied voltage the same but double the available current, you will
have to double the capacitance to use that available current.


                              \\  ~ ~  //
                               (  -at- -at-  )
                           Alfred A. Skrocki
                             .ooo0   0ooo.
                        -----(   )---(   )-----
                              \ (     ) /
                               \_)   (_/