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Re: [TCML] Maxwell #31915 colossal pulse caps

Hi David,

Congratulations on the new additions to the family!
As you probably already know, the Maxwell 31XXX series are usually low pulse rated (1PPS) with a few known exceptions (31393, 31981, and 31583). I suspect, but do not know for a fact, that the dielectric system may use Mylar. If you keep run times reasonable, their large physical size has enough thermal mass that they shouldn't heating up too quickly.
DC is right - give the GA engineering folks a call. They will be more than happy to send you the actual spec sheet if its not a proprietary design. And, if you would please, let us know the actual specs (or make the spec sheet available for the future).
I notice that the eBay seller in Texas seems to have many more of these listed - a bunch of these would make for one really NASTY Marx generator. =<:^O 

Hope you'll be able to make it to the Cheesehead Teslathon this year.

Best wishes,

Bert



David Rieben wrote:

Hi all,

I am now the proud papa of 3 newly acquired Maxwell #31915
100 kV, .44 uF (that's right --  440 nF!) pulse caps with one
more on the way ;^)). Here is an eBay listing of one of these units:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=360079598908&ih=023&category=4662&ssPageName=STORE:PROMOBOX:NEWLIST#LIST

They are of a pretty rotund design with dimensions of 4" x 6"
x 29" long and weigh just over 32 lbs. each. Although I can't seem to find an exact part number match, I was able to find some specs from GA's current line of pulse caps that did seem to have a pretty close match to these. I looked up on General Atomics' (since GA bought out Maxwell) webpage for some specs on these on the closest cap in the way of voltage, capacitance and physical dimensions and found: 

http://www.gaep.com/series-s-ss-capacitors.html

Notice the #31427. It is of the same size physical dimensions
and weight as mine and has a nearly identical voltage/capacitance rating of 100 kV @ .4 uF. Notice though that it is rated for 1 pps ap- plication and is only rated for a 15,000 shot life. However, I am thinking of someday seriesing 2 or 3 of these units for a super Tesla coil cap in the .16 to .24 uF range. It seems to me that with a 200 or 300 kV ceiling voltage rating, these should be pretty 
much bullet proof in a large Tesla coil circuit, even with very re-
latively high primary voltages, say 40 kV or more, since the shot life expectancy goes up almost logarithmically in proportion to a decrease in the applied voltage, doesn't it? Maybe Bert Hickman or Antonio Quieros (spelling?) could clarify here. (hint --- :^) I suppose about the only other possible limiting factor would be the RMS current levels. 

Also, the "measured C" that's on the label is generally about
.48 uF for each cap and my measurements of them so far
has verified a pretty close match - probably measures out to
around 8 to 12 nFd less than what the label says. 
Anyway, tell me what you all think.

David
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