RE: Hosfelt caps

["LOCKWOOD, Chris J." <clockwood-at-orbeng-dot-com.au> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

PUT THEM ON EVERY CAP!!!

If the caps aren't perfectly matched, they will not charge to the same
voltages~ the smaller values of C will have a higher voltage! Given that
these caps are most likely 20% tolerance, this means a maximum variation of
40% between the caps. ie some caps might have 800V, with 1200V across
others! This causes stress to the poor little things.

Also, in terms of bleeding, one resistor in a bank will cause the ends of
the cap to exhibit 0V after a while, but the individual caps will most
likely retain a significant charge- or enough to give a nasty belt days
later.

Ideally the caps should be matched within the strings- bleeder resistors can
only do so much. At fast charge/discharge rates, high R bleeder resistors
will do very little to even voltage distribution. Get a cheap C meter, since
the readings need only be relative, and write the relative C value on the
cap with a permanent marker. Then they can be sorted into best matching
strings!

Chris

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Friday, August 11, 2000 1:25 PM
To: tesla-at-pupman-dot-com
Subject: RE: Hosfelt caps


Original poster: "Oxandale, Terry" <Toxandale-at-SPP-dot-org> 

Wow, when I ordered mine two months ago they had over 3000 caps in
stock. To put this in perspective, it took over a year to sell their
first 1200 of these caps. Glad I got mine when I did. BTW, I let loose
on mine today. I am running 12/string (36kvdc-9kvac) and put 20kv into
the tank for about 10 minutes, and the caps BARELY got warmer. The spare
caps (will be using them for a bigger coil) accidently took several hits
from the coil, but still work like new. Also (hope no one flames me on
this) I have not used any resistors across the caps (due to the
construction technique of the strings), but do have one across the
entire string. Is this an acceptable drain or am I
mistaken?.......anybody?

Terry (the Un-Terry) 


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