Re: Maxwell AC vs. DC ratings

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Edward Wingate <ewing7-at-rochester.rr-dot-com> 

Tesla list wrote:
 >
 > Original poster: Terry Fritz <teslalist-at-twfpowerelectronics-dot-com>
 >
 > Hi Ed,
<snip>

 > There are probably close to 20,000 MMC caps out there.  Unexplained
 > failures number about 5 ;-))  with a little more time, we will figure out
 > these interesting failures with John's coil too!  Last year we asked
 > everyone if there were any problems they were having with MMC or the
 > resistors and no new or serious problems were reported.

Terry,

Just how many commercial pulse caps do you think are out there working
just fine without failures? I'd bet it's significantly more than 20,000!

<snip>
 > You are not a beginner now and you use the caps best for your advanced
 > coils.

My latest "advanced coil" has a secondary that is 4.25" long and 1.125"
in diameter and is wound with 850 turns of #38 (.004") magnet wire. The
entire coil with 20 ma kV transformer and 3 gap tungsten stationary gap
will fit in the palm of your hand. The capacitor on this coil is a 5000
volt .001Mfd bathtub mica, $2 hamfest special. NO MMC!! The bathtub is
smaller and neater.

 > >All that said, I can't wait to fire up the maggy for the first time this
 > >year after I get the lab open and have one of the aforementioned
 > >commercial caps go up in a blaze of sparks and smoke. :^) That would be
 > >just my luck!
 >
 > Chances are very good they will do fine.  If a cap is really going to blow
 > up from stress, chances are it will be within minutes.  After all this
 > time, I bet your coils and caps have proven to be able to live happily
 > together.

Terry, the second sentence isn't really true. The "infant mortality
rate" that applies to many modern electronic devices doesn't apply to
the pulse caps I use. They have a mean shot life that is calculated from
dielectric thickness, voltage, pulse rate, etc. Roughly calculated, my
maggy caps have over 60 million shots on them. How many million shots
are left in them is an unknown.

Ed Wingate RATCB