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RE: EMMC Value Drift

At 06:31 AM 7/8/99 -0700, you wrote:
>Terry,
>
>I'm running the heck out the same Panasonic caps (the ECW series).  My setup
>is slightly different in that I'm using two strings of ten .033uf for a
>total C=6.6nf  
>
>Initial measurements after construction were 6.6?nf (I didn't document the
>accuracy any further at that point).  I re measured the assembly last night
>and found they are 6.64nf (no degradation that I can see).  I then ran them
>hard for 5-min straight and on and off for another 5-min. Measurements after
>they returned to ambient temp. remained at 6.64nf  I'll continue to monitor
>them as they log some more time (30+ min at this point).
>
>Testing is on my Mini-Twin (bipolar coil), driven with a 12/30NST, and a
>loaded frequency of approximately 500khz. These caps took a lot of abuse
>while I was setting up this coil (including a primary strike). Last nights
>settings are as follows:
>
>1)135v input to NST
>2)NST Safety gap set so it just doesn't fire at 135v
>3)RQ widened until Safety gap just starts to fire
> 
>Hope this is of some value and keep up the great EMMC work
>Brian D. Basura
>
>
>snip...

Hi Brian,

	This is very helpful!  I would normally run the caps in strings of twenty
instead of ten.  As far as I can tell, the problems that show in my EMMC
design would be very minimal with twice as many caps.  I am far less
worried at this point.  My EMMC may eventually die from the ionization but
I am very pleased that it works as well as it does given the high stresses
on it.  I think I just got a little too close to the edge. :-)

	I am now very convinced that poly caps can easily take TC stresses
provided we don't push their limits "too" far.  However, even when we do,
deliberately or accidently, they appear to be more than capable of handling
tremendous abuse.  If one wants a rock solid Tesla cap with proven margins
and well known characteristics, the MMC caps are the only way to go.  There
is really nothing left to chance.  A good conservative design could easily
last forever.  We have pushed them to their limits and found that those
limits are far beyond what we ever could have wished for.  As far as I
know, no other Tesla cap has ever been tested to the high degree that MMCs
have been and our knowledge of them is excellent.  

	MMCs can take over voltages and even internally arc with practically no
damage.  They can be configured for virtually any voltage or current need.
If there is a failure, it is fairly easy to determine and correct the
cause.  If one wants a quick cheap cap, you can run them well over their
rating and expect acceptable life out of them.  They are repairable.  They
are easy to make and require no oil...  No doubt about it, the are THE
choice for Tesla caps now.

Cheers,

	Terry