RE: Please help with capacitor

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

Original poster: "Philip Brinkman" <peeceebee-at-mindspring-dot-com> 

Wow, thanks Gary, and Ed, and Robert for all the help, I re-did the
calculations and also came up with 1.012 pf per plate, and if it doubles in
a stack, that is great too, I am usining notebook cover pages, which, I
think is much higher quality than the hardware sheets of plastic, I know I
am pushing the limits, but I'm going to try it with 6 layers of 5 mil
plastic just to see how it holds up.. I already blew up one cap made from
zip lock bags and I know this plastic is much stronger. I'm also
filling/coating each sheet with mineral oil...hope this helps too. Anyway
thanks again for the help and encouragement... cap should be done this
weekend.
  Phil.


 > [Original Message]
 > From: Tesla list <tesla-at-pupman-dot-com>
 > To: <tesla-at-pupman-dot-com>
 > Date: 1/8/2004 1:38:28 PM
 > Subject: RE: Please help with capacitor
 >
 > Original poster: "Lau, Gary" <gary.lau-at-hp-dot-com>
 >
 > A home made cap used with a 15kV power supply must be made from at least
2
 > or 3 individual caps, in series.  A single
 > cap will fail due to corona at the edges of the foil.  I spend a huge
 > amount of effort on two attempts at rolled poly caps.  The first used a
 > single layer of 40 mil poly, and dies after a few minutes.  The 2nd
attempt
 > was made with two units in series, each with a single layer of 40 mil
 > poly.  It too died after several minutes (see
 > http://www.laushaus-dot-com/tesla/rolledcap.htm).
 >
 > Assuming you are using 60 Hz power, your cap is mains-resonant with the
 > NST, and this is a bad thing.  In addition to being healthier for the
cap,
 > I have found that a value of about 2X the mains-resonant value gives the
 > best performance with a static gap.
 >
 > Regards, Gary Lau
 > MA, USA
 >
 > -----Original Message-----
 > From: Tesla list [mailto:tesla-at-pupman-dot-com]
 > Sent: Monday, January 05, 2004 7:09 PM
 > To: tesla-at-pupman-dot-com
 > Subject: Re: Please help with capacitor
 >
 >
 > Original poster: "Philip Brinkman" <peeceebee-at-mindspring-dot-com>
 >
 > I'm making a new flat plate capacitor for use with my 15,000 volt 60 ma
 > NST. I'm using aluminum foil plates 7.5"x9" (67.5 sq. in.) with 30 mil
 > polyethelyne (6 layers of 5 mil each) between each plate. Using the
formula
 > C=kA/d (k=2 ) I get 3.25 sq. meters or 74 plates, does this sound right?
My
 > last capacitor had only 30 plates. I'm aiming for .013 microfarads.. is
 > this right? Using different programs I get different values of capacitor
to
 > use.
 >