Re: [Bulk] Re: [TCML] ANOTHER ONE DOWN, ANOTHER 37667 BITES THE DUST

["drieben" <drieben@xxxxxxx>]

Hi Adam,

Yes, the 35 kV rating of these 37667 units seems to
really be "running on the razor's edge" for failure when
pushing voltages  > 12 kVAC and seriesing them in
2's for a 70 kV rating does seem to properly address
this issue. From what I've been able to gather, I would
opt for a capacitor voltage rating at a minimum of 3x
the maximum AC RMS voltage that is anticipated from
the transformer. Both Cameron Prince and I have expe-
rienced failure with a .1 ufd, 50 kV rated Hiptronics
pulse cap in our large Tesla coils, driven by a 14.4 kV pig,
that was overdriven to 16.8 kV through variacs. That
would place the Hipotronics unit right at the 3x rule with
a 16.8 kV(AC) input. After switching to a 75 kV rated
Maxwell unit, we've experienced no more problems.
The > 3x voltage rating provides a safety cushion for the
very high voltage reversals experienced in a Tesla coil
circuit.

David Rieben





----- Original Message ----- 
From: "Yurtle Turtle" <yurtle_t@xxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Sunday, May 13, 2012 4:35 AM
Subject: [Bulk] Re: [TCML] ANOTHER ONE DOWN, ANOTHER 37667 BITES THE DUST


I have used 10 in series/parallel for over a decade in 25 kVA use on a 10" 
coil and they are still fine. I bought them in at least four different 
"buys", so who knows the abuse they suffered before me, but they have 
performed admirably, as long as you use two in series.

Adam

________________________________
From: MICHAEL HARDY <mhardy4@xxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Saturday, May 12, 2012 11:15 PM
Subject: [TCML] ANOTHER ONE DOWN, ANOTHER 37667 BITES THE DUST

When I first decided to build a pig powered coil (2004 ), I searched for 
pulse caps on the internet, and of course the infamous 37667's were 
everywhere. Bought 5 at $100 each. Then found out they weren't very good for 
TC's. I've since been running 3 TC rated Maxwell 0.2uF, 20 kV caps in 
series, for 0.066uF @ 60kV. This on a 14.4 kV Pt powered 6" coil system 
running around 4800 watts with no problem. I have recently completed a 15" 
coil running at about 15 kW. I used 2 banks (including the one above) in 
parallel for 0.14 uF at 60 kV. I still am running the smaller coil 
routinely. Changing out one bank is a pain, so decided to try a pair of 
37667's in parallel (0.06 uF @ 35kV). Ran good with only slight warmth to 
cases of caps. Short 30 sec runs with 3 minute pauses. After a half hour I 
saw steam from the cap bank. Checked, and one of them had split open. DON'T 
BUY 37667 MAXWELL'S FOR TC USE!
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