Re: Bang size and break-rate
At 08:35 PM 6/9/1999 , you wrote:
>Original Poster: Finn Hammer <f-hammer-at-post5.tele.dk>
>It is my impression, from my own experience, and from looking at
>numerous sites, that the first coil that a person builds is made to meet
>the "many primary turns" criteria, the next, and bigger coil is
>frequently not. Many of the big coils have 4-5 turns primarys, Bill
>Wysoc`s model 14 has only 2. (ok!, it`s a maggie, but still...)
>So, is there some mechanism inherent in really big coils that allow for
>these low primary turns counts, or are the newcomers making a lot of
>primary turns in vain, for the sake of a (perhaps) outdated tradition.
>If not, I would feel tempted to push for 30 kV in my next design, for
>low C, high L, even though I alresdy have experienced some of the
>problems of insulating to 20 kV in my present tank circuit.
Hello Finn and all,
Well my first question is, what is the inductance of the primarys on these
"big" coils? And what are the primary C's? Few turns of a very large
diameter can still be a very high inductance. Second, I wonder what ration
of primary C to primary L (for same F, of course) is best? The $1000 question?
Finn, how hard are you pushing your MMC's? Are you operating at peak AC=DC
rating? Or 2X, 3X AC = DC? I know Terry is experimenting with pushing the
envelope on those Panasonic caps. Speaking of which, I toasted one in my
tube coil a while back. I was running a string of 5 1600 VDC Panasonics in
my tank using the Level Shifted method (as described by Dave Sharpe and
John Freau) and had no more than 2400VAC into it, so the caps should not
have seen more 7000V, but one failed at the center of the string. It popped
and on inspection was in two pieces. Perhaps they do not like the spike you
get from using the Level Shifter...
30KV? Definitely lower C would be best at such higher voltages, wouldn't
it? At least to keep dialectic losses down. Perhaps I should find out if
the X-Ray transformer I have my eyes on is three phase or not, I'm sure I
could figure out a way to get it down to 25KV, or so.