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BIG Capacitors




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From:  HomerLea-at-aol-dot-com [SMTP:HomerLea-at-aol-dot-com]
Sent:  Thursday, February 19, 1998 12:07 AM
To:  tesla-at-pupman-dot-com
Subject:  Re: BIG Capacitors

In a message dated 98-02-18 20:14:05 EST, you write:

> From:  Edward V. Phillips [SMTP:ed-at-alumni.caltech.edu]
>  Sent:  Tuesday, February 17, 1998 11:54 AM
>  To:  tesla-at-pupman-dot-com
>  Subject:  Re:  BIG Capacitors
>  
>  Justin:
>  
>          Any idea how big a 100 uF 18 kV capacitor would be?
>  You can get 4800 ufd 450 volt electrolytic capacitors pretty
>  cheaply at swap meets (less than a buck around here).  40 of
>  those in series would be 120 ufd at 18 kV, if you could 
>  equalize the voltages with shunt resistors across each 
>  capacitor.  Since typical leakage is of the order of 2 ma,
>  that wouldn't take too much power.  I have used one of these
>  very successfully in a magnet charger, and think the series
>  resistance isn't more than a couple of ohms.  Have looked at
>  the can crusher page, but can't remember how many turns on
>  the primary, so hard to judge what peak current is.  This
>  may or may not be a foolish idea, but I'm sure discharging
>  such a bank would be pretty spectacular.
>  
How does the peak current from this type of stack compare to real pulse
discharge caps? It seems like it should be much lower. My 20kv 14mfd caps have
only .035uH inductance.

jim heagy