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BIG Capacitors
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To: "'Tesla List'" <tesla@pupman.com>
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Subject: BIG Capacitors
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From: Tesla List <tesla@stic.net>
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Date: Thu, 19 Feb 1998 00:18:38 -0600
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Approved: tesla@stic.net
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From: Bert Hickman [SMTP:bert.hickman@aquila.com]
Sent: Wednesday, February 18, 1998 11:43 PM
To: Tesla List
Subject: Re: BIG Capacitors
Tesla List wrote:
>
> ----------
> From: Edward V. Phillips [SMTP:ed@alumni.caltech.edu]
> Sent: Tuesday, February 17, 1998 11:54 AM
> To: tesla@pupman.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.
>
> Ed
Ed and all,
I suspect the big electrolytics couldn't withstand the voltage
reversals. This is not normally a problem with a magnetizer, since as
you know the coil is typically "crowbarred" (short-circuited) near the
first current maximum point, and the caps never see a reversal. However,
this is not the case for simple can crushers, where an 80-95% voltage
reversal is the norm...
I think you're correct about it being a spectacular discharge especially
if the electrolytics explosively vented... :^)
-- Bert --