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Re: Capacitor Help
Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>
Steve, Curt, Malcolm,
Yes, in Malcolm's case, the MMC would certainly be his "best bet".
However, with large pole pig driven systems,
a large commercial oil-filled pulse capacitor is actually more
practical and probably more economical, too. My "Green Monster"
coil http://dawntreader.net/hvgroup/david/gm.html uses a .1 uFd
(100 nFd), 50 kV Hipotronics pulse cap for the primary C and a 15
kVA, 14,400 volt pole pig. With the variac
turned up to max, I get 280 volts input and nearly 17 kV
output from the pig. Although I certainly could build an
MMC to handle this, it would require say 225 (15 strings
of 15) of those .1 uFd, 2 kV snubber caps to get a relative-
ly safe total voltage rating of 30kV at .1 uFd total C. Even at Richard-
son Electronics' $1.99 each for these, that would still be about
$450 plus shipping, not to mention the headache of soldering
225 individual capacitors (and 225 bleeder resistors) together ;^0
David Rieben
----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Monday, December 12, 2005 4:07 PM
Subject: Re: Capacitor Help
Original poster: Steve Ward <steve.ward@xxxxxxxxx>
I would most certainly disagree here. An MMC is more robust and gives
more "bang for your buck". Sticking with the CDE 942C series (go to
rell.com to order them) you will have no question as to the
suitability of the capacitor.
Maxwells would be fine if they were new, but in fact most of the
maxwells out there (sold by alltronics) were supposedly quite abused
in an experiment where they discharged banks of these caps into a
spark gap to generate sound to break up kidney stones (dont know if
this ever went anywhere). This is just "word of mouth" stuff, but it
seems plausible enough. Anyway, why not spend less money and get a
new capacitor? Its better than guessing at its suitability and
lifetime.
For a 15/30 NST, a string of 12 of the .1uF 2kV CDE caps would work (i
believe the part number is 942C20P1K.
But ouch, it looks like RELL (or CDE) increased the minimum order to
~$133. I believe there was another place that sold CDE caps, Gerry R.
mentioned it before. I think it was:
http://mpaqelectronics.com/
But it seems like you have to call and ask about them?
Good luck.
Steve Ward
On 12/12/05, Tesla list <tesla@xxxxxxxxxx> wrote:
> Original poster: "C. Sibley" <a37chevy@xxxxxxxxx>
>
> I'd go with a Maxwell pulse capacitor. The can be had
> on e-bay for around $100 and are well worth the $$$.
> The have very high peak current and very low
> inductance. If this is your first coil (and not your
> last) you will have room to grow as you build more
> powerful coils...
>
> Search e-bay for "Pulse Capacitor" and look for the
> big square white block type capacitor.
>
> Curt.
>
>
> --- Tesla list <tesla@xxxxxxxxxx> wrote:
>
> > Original poster: "MalcolmTesla"
> > <tesla@xxxxxxxxxxxxx>
> >
> > Hi everyone,
> >
> > I'm almost done building my first tesla coil. I
> > used a 15kv 30mA neon sign
> > transformer as my source. I have a spark gap made
> > with two nuts welded to L
> > shaped brackets with bolts threaded in. I can
> > adjust the gap by threading
> > the bolts back and forth. There is a very powerful
> > 110v squirrel cage fan
> > cooling the spark gap.
> >
> > My concern is the capacitor. I'm trying to purchase
> > something and just not
> > sure what to get. I've been searching google.com
> > and looking at sites until
> > my eyes can't take it anymore.
> >
> > I can tell from everyone's sites that Polypropylene
> > or Polyethylene is the
> > way to go. I can get those from mouser.com but they
> > are only 1k to 3k and
> > the just look so darn tiny compare to the pictures I
> > see of everyone else's
> > on the net it's got me worried I'm getting the wrong
> > thing.
> >
> > If anyone can help me out with capacitor values I
> > need, where to purchase,
> > etc. I'd be very grateful. I did find one at
> > amazing1.com but it was $750.
> > Wow
> >
> > Thanks
> > Malcolm
> >
> >