Re: Geek Caps - Ratings and longevity

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

Original poster: "jimmy hynes by way of Terry Fritz <teslalist-at-qwest-dot-net>" <chunkyboy86-at-yahoo-dot-com>

Hello Terry,

Where did you get the 3500 number? The MMC section on
your page said that the one you tested failed at 5700
volts. Was it the testing of the newer capacitors? I
"thought" I heard a higher value for the new ones too.
--- Tesla list <tesla-at-pupman-dot-com> wrote:
 > Original poster: "Terry Fritz" <teslalist-at-qwest-dot-net>
 >
 > Hi Chris,
 >
 > At 05:43 PM 7/2/2003 -0700, you wrote:
 > >Hi guys,
 > >It's been about 5 months since I have gotten my 6
 > inch coil working, and
 > >up until now it has been running perfectly. About a
 > week ago though, the
 > >coil started acting strange. It only makes sparks
 > about half as big as
 > >they should be and it makes a strange hissing noise
 > while running. I
 > >checked the NST and it still works perfectly. I
 > also looked at the spark
 > >gap but nothing seemed out of the ordinary there
 > either. I double checked
 > >the connections everywhere and they were fine also.
 > So I now have to be
 > >suspicious of my MMC again. This time at least,
 > they didn't blow up
 > >immediately so I know I'm doing at least someting
 > right. =D
 > >The MMC is 2 strings of 6 geek caps, giving it a
 > value of .5ufd and a
 > >12000 volt rating. My transformer is a 9kV 120ma
 > NST, so it should be fine
 > >with the RMS voltage. However, the peak voltage on
 > the transformer is
 > >somewhere around 12500 right?
 >
 > 9000 x SQRT(2) = 12728 Volts.
 >
 > >I know that these caps are made to tolerate quite
 > above their ratings, but
 > >over time could they eventually break down from
 > repeatedly running them
 > >above their ratings?
 >
 > Unlikely in very limited use.  Geek caps snap at
 > about 3500 volts each.
 >
 >
 > >  The outer tape covering the caps are now severly
 > wrinkled and covered
 > > with dents, which may be where they were blasted
 > through.
 >
 > If they are "new" dents and wrinkles, that would be
 > "bad".  CD caps
 > normally are a little rugged on the outer surface
 > and they may settle with
 > time.  However, if they are obviously "falling
 > apart" during use, something
 > is wrong.
 >
 > >Either that, or something else is wrong and the
 > tape may just be wrinkled.
 > >Terry, would you mind doing another MMC inspection
 > to see if these things
 > >still work?
 >
 > I can certainly check them here if you want to send
 > them to me.  As far as
 > I know they should work fine, but if you think they
 > are the 6x2 string
 > things needs a check we can certainly do it.  A nice
 > high resolution
 > picture close up of a "bad" cap sent to me may work
 > just as well too.
 >
 > Cheers,
 >
 >          Terry
 >          terrellf-at-qwest-dot-net
 >
 >
 >
 > >-Chris
 >
 >


=====
Jimmy

_