Re: Newark ebay capacitor: primary tank capacitor?

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

Original poster: Koen van den Berg <cerberus_rex-at-planet.nl> 

Hi Eric

Whoa! 4(!) MOTs? Powering a 3 inch coil? Somehow that 3.3 nF just doesn't
sit right with those specs. I'd think more along the lines of 33 nF, if not
much more. If you're using 4 MOTs you have some serious power going there,
and a reasonable voltage input. I mean, it's not a pig, but it's a lot
beefier than a NST current wise. I'm using two 10 kV 50 mA NST's and I have
a 32 nF capacitor bank with 48 942C's. That works nicely. I don't think your
3.3 nF bank will work great (read: last long) if you feed it ~8 kV at 200 -
300 mA. Those 942C's are looking a lot better, all of a sudden. If I were
you I'd add some MOTs to your stack, ballast it so it won't fry your MMC,
and get the CD caps. Yep, they are Cornell Dubilier Caps, and you can buy
them off the Geek Group if nowhere else. I'm sure somebody else can help you
out a bit more in that area. They have reasonable prices, and the caps are
really excellent. If you don't want to go there just yet, maybe you should
just make your own caps. It's a pain, but it would work for a while. And
don't let those MOTs bite you... :-)

Koen


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Wednesday, February 25, 2004 7:24 PM
Subject: Re: Newark ebay capacitor: primary tank capacitor?


 > Original poster: "Hydrogen18" <hydrogen18-at-hydrogen18-dot-com>
 >
 > Gah forgot to say, would 10 of the 3300 pf, or 3.3 nF, in paralell be
 > suitable for a 3 inch coil with a 4 pack mot supply?
 > ----- Original Message -----
 > From: "Tesla list" <tesla-at-pupman-dot-com>
 > To: <tesla-at-pupman-dot-com>
 > Sent: Wednesday, February 25, 2004 8:27 AM
 > Subject: Re: Newark ebay capacitor: primary tank capacitor?
 >
 >
 >  > Original poster: "Virtualgod" <mike.marcum-at-zoomtown-dot-com>
 >  >
 >  > With doorknob types, it's hit or miss. The ones that are not rated for
rf
 >  > will overheat and die. Not sure if there is a way to tell just by
looking
 > at
 >  > them. Usually I've seen a seen a dozen or so 30-40kv ones in parallel
to
 > get
 >  > the capacitance needed. Considering the cost of that (~$10-20 each),
 > better
 >  > off getting 942c's where you know what you are getting.
 >  > ----- Original Message -----
 >  > From: "Tesla list" <tesla-at-pupman-dot-com>
 >  > To: <tesla-at-pupman-dot-com>
 >  > Sent: Tuesday, February 24, 2004 11:22 PM
 >  > Subject: Re: Newark ebay capacitor: primary tank capacitor?
 >  >
 >  >
 >  >  > Original poster: "Hydrogen18" <hydrogen18-at-hydrogen18-dot-com>
 >  >  >
 >  >  > Alright ,what about these caps:
 >  >  >
 >  >  > http://cgi.ebay-dot-com/ws/eBayISAPI.dll?ViewItem&item=2597981535
 >  >  >
 >  >  > sry if I'm being annoying.
 >  >  >
 >  >  > ---Eric
 >  >  > ----- Original Message -----
 >  >  > From: "Tesla list" <tesla-at-pupman-dot-com>
 >  >  > To: <tesla-at-pupman-dot-com>
 >  >  > Sent: Tuesday, February 24, 2004 5:51 PM
 >  >  > Subject: Re: Newark ebay capacitor: primary tank capacitor?
 >  >  >
 >  >  >
 >  >  >  > Original poster: Bert Hickman <bert.hickman-at-aquila-dot-net>
 >  >  >  >
 >  >  >  > Tesla list wrote:
 >  >  >  > >Original poster: "Hydrogen18" <hydrogen18-at-hydrogen18-dot-com>
 >  >  >  >
 >  >  >
 >  >
 >
 >http://cgi.ebay-dot-com/ws/eBayISAPI.dll?ViewItem&item=2597989262&category=4662
 >  >  >  > >could that capacitor(in series obviously) handle the stresses of
 >  > primary
 >  >  >  > >tank capacitor duties? Also, can some1 point me to reference so
I
 > can
 >  >  >  > >convert uf to nf, pf and uf, and so on? I know 10^-9 is nano and
 > 10^-6
 >  > is
 >  >  >  > >micro but that doesnt mean much to a mid class geometry student.
 >  >  >  > >
 >  >  >  > >.
 >  >  >  >
 >  >  >  > Dear (what's your name?),
 >  >  >  >
 >  >  >  > These caps are Mylar. Because they are very lossy under RF use
and
 > the
 >  >  >  > package does not allow for "graceful" expansion, they tend to
become
 >  > oily
 >  >  >  > firecrackers when used in Tesla Coil tank circuits. They are
usable
 >  > only
 >  >  > as
 >  >  >  > DC filter caps, in voltage doubler circuits, or in low pulse rate
 >  > (non-RF)
 >  >  >  > applications.  :^(
 >  >  >  >
 >  >  >  > 1 uF = 1,000 nF = 1,000,000 pF
 >  >  >  > 1 nF = 0.001 uF = 1,000 pF
 >  >  >  > 1 pF = 0.001 nF = 0.000001 uF
 >  >  >  >
 >  >  >  > These caps are 0.25 uF = 250 nF = 250,000 pF
 >  >  >  >
 >  >  >  > Best regards,
 >  >  >  >
 >  >  >  > -- Bert --
 >  >  >  > --
 >  >  >  >
 >  >  >  >
 >  >  >  >
 >  >
 >  >
 >
 >
 >