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Ganging Caps (fwd)





---------- Forwarded message ----------
Date: Sun, 28 Sep 1997 14:23:57 -0600 (MDT)
From: Chip Atkinson <chip-at-pupman-dot-com>
To: tesla-at-pupman-dot-com
Subject: Ganging Caps

From: 	Jim Lux[SMTP:jimlux-at-earthlink-dot-net]
Sent: 	Thursday, September 25, 1997 10:05 AM
To: 	Tesla List
Subject: 	Re: Ganging Caps

You might have a problem with series inductance stringing thousands of
those units in series.  This can be addressed in some ways by proper cans
around the cap, arranging the caps properly, and they might be wound
suitably to reduce the L.  For tesla coil use, it does you no good if the
ESR is too high for the ganged up unit, or if it is self resonant in the
wrong place.

Just for example, if you rearrange the 5 cap rolls from 100 uF/1500V to 4
uF/7500V, the series L will increase by a factor of 25(!).  Can you
tolerate this?

> Yes, I do have a real question to any and all. I am thinking about
> ganging caps. The idea is to make one "huge variable cap" (or a few). I
> have "several" CSI (manf.) caps rated at 100uF and 1500vdc. Tearing one
> of these apart, I found 5 cap-rolls paralleled. Each roll of course is
> it's own cap measuring 20uF. I did the math and found I had enough to
> get down to 0.001uF if series'd up (yes, I have a bunch). I could even
> create up to 160 or so tap points for varying capacitance's. The idea,
> is a cap that could be used for almost any coil, robust, etc... The
> voltage rating (ac not dc) should be "null" so to speak with this many
> rolls series'd. Of course, the voltage rating and capacitance would vary
> depending on tap configuration.