Re: MMC Caps

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

Original poster: "Rob Judd by way of Terry Fritz <twftesla-at-qwest-dot-net>" <canska-at-a5-dot-com>

My thanks to all who replied! I'm definately going with the LTR value for
whatever combination of nsts I run (2 or 3 probly). I'm using a saltwater
tank cap now... 9 wine bottles in a fish tank full of brine and oil. It
works and produces decent output but its a disaster to keep clean,
troubleshoot, and modify, and its very lossy. And its impracticable to
transport it at all. I'll dance for joy the day I can dismantle it for good!

So, I'm going to get about 30 of the caps and start with LTR, using the
formula (pi / 2) * Cres, with 2 nsts and see how it goes, then try LTR for 3
nsts. I'm sure it will work alright. If I do blow it up, I can always buy
more I suppose :-) I'll let everyone know how it goes if anybody is
interested. Probly will be a while though until I get the caps.

Rob Judd

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Friday, October 25, 2002 12:23 PM
Subject: Re: MMC Caps


> Original poster: "Sean Taylor by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<taylorss-at-rose-hulman.edu>
>
> Hi Rob,
>
> > I've got 3 NSTs, each 15kv 30ma. So for 15kv 90ma the resonant tank cap
> > would be 0.0159uF. In theory, one string of 10 of these caps should do
it.
> > The actual capacitance would be .0150 and should take 10 caps * 2kv =
20kv
>
> You really are pushing the limit of the caps . . . especially since the
peak
> voltage of your NST bank is going to be about 21.2 kV (sqrt(2)*15).  The
> caps will handle higher than 2 kV, BUT, if you use just 10 of them, you'll
> be very close to running resonantly (almost exactly), so incredibly high
> voltages are possible should the gap not fire, or something come
> disconnected.  I would go for 2 strings of 13, more $ I know, but it would
> put you into LTR, so you wouldn't get the resonant rise, you would have a
> higher RMS and peak current capability, and they will probably last a lot
> longer.
> You could also just use 2 of your NSTs with a single string of 10, which
> would make the system LTR, and you wouldn't get the resonant rise.  The
caps
> would also load down the NST so you wouldn't get the full peak voltage
> stressing the caps every cycle.  That may be an option if you don't want
to
> spend extra on caps . . .
> If you want to go for the 1 string of 10 and all 3 NSTs, you can try it,
> they'll probably hold up for a while (Terry probably has a better idea of
> that), especially if you're careful!  That's just my opinion, I'm sure
> you'llget plenty more :-)
>
> Sean Taylor
>
>
>
>