Re: MMC Cap Papers and MMC Life Prediction

Hi Terry,

Thanks for all your work on MMC life prediction. Your
newest HTML file really proves the gut feel I had about
those WIMA FKP-1 33nF/6kVdc/700Vac caps. They
arenīt worth a darn, which is what I also told the GTL
gang, but... they went ahead and ordered them (and
caught me off gaurd) anyway. The 100nF/1600Vdc
/650Vac would have been a *MUCH* better buy. My
present MMC setup (with those cheaply bought) ERO
caps has a life prediction of around 2000hrs (of which
there are now "only" 1996.5 left ;o}).

Very interesting papers, I must say. I DO have to
disagree with one thing you wrote, tho:

> Original Poster: Terry Fritz <twftesla-at-uswest-dot-net>
> Hi All,


> primary systems.  Since the length of the output arcs is proportional
>to the input voltage, there is always a desire to use as much primary
>voltage as possible.

NO, NO and once more NO!! ;o) I have proved this with my 8" coil.
The length of the output sparks is NOT (!!!) soley dependant on
the input voltage. Otherwise, how would I be getting 63" sparks
from a 7500V NST -at-1275VA? I consider the "need-for-high-
voltage" story to be other one of those myths. True, there are
limits (either low or high), but it is NOT necessary to use high
voltages for long spark lengths. Both low and high voltage
systems (AND vice versa for the current) have their advantages
and their disadvantages. I think it is safe to say the spark length
depends almost purely on how much raw power you shovel into
the coil (VA, BPS, J must all be considered), but if you build
two systems with equal power (VA, BPS, J) and one having a
15kV xformer and the other being powered by a 7500V xformer,
there will be no (or only very little) difference in output arc length.
Of course there are other things, which determine the spark
length (like the gap design, toroid size), but these are of a more
secondary (fine tuning) nature. Another "biggy" (at least from
my experience) in spark length increase is the size of the
secondary. Performance improves as the secondary gets larger
in diameter AND length. For equal input (wall) power, I found
that my 8" secondary will give me some 40% longer sparks
(100cm vs 60 cm -at- ~400VA) than my 3.34" coil did.

I donīt mean to flame you, but I just had to say this (from my
own findings) about high vs. low input voltage. Please, no
hard feelings! ;o)

Coiler greets from Germany,
(keeping his fingers crossed, that Terry
takes the words as they are ment).