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Re: [TCML] Maxwell #31915 colossal pulse caps
Hi Phil,
Thanks for the response. Yes, if I was considering using one of
these at a significant percentage of its nameplate voltage rating,
then I would not have given them a second thought. However,
due to their relatively huge cpacitance along with their 100 kV
rating, I was thinking of using a minimum of 2 (and probably 3)
of these in series to get the capacitance down to more "down to
earth" levels for even a large Tesla coil setup. I think Kevin
Eldrege (the BIGGG Tesla coil in Oklahoma) only uses .188
uF total C with his behemoth Telsa coil. So with just 2 of these
seriesed, we're still looking at ~.24 uF (most of them have a
"measured capacitance" of about .48 uF) at a whopping 200 kV!
Of course, with 3 of them seriesed, that would be good for about
.16 uF at 300 kV! Of course, this would make for right at 100 lbs.
of capacitor alone! Even though they only have a life expectancy of
15,000 "shots" at their rated voltage w/ 20% V-reversals, and even
if they've already had some life used out of them, I would expect
that unless they happen to be just about dead already, 2 or 3 of them
seriesed should not be even remotely stressed, even by running them
several hundred PPS, when the applied voltages are almost certainly
never going to be >30 kV, AC or DC. According to General Atomics'
X-Y graphs, just by decreasing the applied voltage to 30% of the cap's
rating, you increase the "shot" life expectancy by 10,000X! At 300 kV,
30% is still 90 kV, so I would not even be surpassing 10% of the cap
combo's total voltage rating! Even with just 2 of them, I would never
be using them at more than 15% of their combined namplate V rating.
Happy coiling,
David
----- Original Message -----
From: <FIFTYGUY@xxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Thursday, August 14, 2008 4:33 PM
Subject: Re: [TCML] Maxwell #31915 colossal pulse caps
The price was good, but I need another big cap like I need a hole in
my
head! :) Anyhow, I speculated that they *might* work OK as TC primary
caps,
since they'd be running at a fifth of their rated voltage. But another
thing
that bugged me was the low lifetime number of pulses - no telling how
much
these puppies have seen, or how long they'd hold up at reduced voltage
but more
severe-duty primary tank use. So I passed.
One thing I thought they might be fun for would be the "discharge a
big
cap through a streamer off a TC" trick. I believe they will operate in
the
horizontal position, so they should be easy to charge at the base of the
secondary.
Glad they went to a good home, and glad to know they went to a fellow
TCML member. Sorta like "keeping them in the family". If you ever want to
get
rid of one, lemme know!
-Phil LaBudde
Center for the Advanced Study of Ballistic Improbabilities
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