Re: All capacitors great and small, and depotting question

To: tesla-at-pupman-dot-com
Subject: Re: All capacitors great and small, and depotting question
From: "William R. Langston" <blangsto-at-iwvisp-dot-com> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Thu, 07 Oct 1999 12:22:23 -0600
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

I too am interested in a group buy. I could make good use of a couple of
hundred caps. Let's talk further.

Bill Langston

Tesla List wrote:

> Original Poster: Aric_C_Rothman-at-email.whirlpool-dot-com
>
>      I had the good fortune to obtain a scrap roll of 14" wide, 2 mil
>      think, 300 foot FEP (Fluorinated Ethylene Propylene).  FEP is one of
>      the forms of Teflon, and it has properties which suggest it would be
>      suitable for use in making caps for TC service.
>
>      Dissipation Factor (1 MHz): 0.0006
>      Dielectric Constant: 2.0
>      Dielectric Strength (DC, 1 mil): 6500 V/mil !!!
>
>      WRT dielectric strength, the value per mil decreases as the film
>      thickness decreases (the 20 mil film is rated at only 1800 V/mil).
>      Now, I know 10 sheets of 2 mil film will have a greater dielectric
>      strength than one sheet of 20 mil material (this issue has been
>      addressed on this list many times), but may one simply add the
>      dielectric strength ratings of each stacked sheet, or is there a
>      diminishing return as a new layer is added?
>
>      I would like to conservatively derate the film to 2000 V/mil and make
>      strings of 5 capacitors in series, each with two 2 mil layers of FEP,
>      for service with a TC driven with a 15,000V NST.
>
>      What do you think?
>
>      Also, I received a quote for pulse caps which I think are suitable for
>      a MMC.  The manufacturer is Seacor, the type is KP25, and the value is
>      0.047uF, 1600 VDC.  The caps are $0.79 each, with a minimum order of
>      500 pieces.  Anyone interested in a group buy?  Data can be found at
>      the URL http://www.seacorinc-dot-com/Tables/high_pulse.htm  The company
>      claims the KP25 family is a cross for the Wima FKP1 family.  The KP25s
>      are polypropylene, internally series connected, 1000+ V/uS rated, and
>      foil terminated.  Everything you'd want in MMC cap!...I think :)
>
>      Also also...
>
>      I depotted a 15kV, 60ma NST.  I pulled the top off it and roasted it
>      over a Coleman campstove.  The tar above the core softened, but failed
>      to melt, but the tar beneath was boiling!  I finally decided to pull
>      away the upper layer of tar.  In doing so, I pulled off a layer of
>      windings on both secondaries.  While soaking the core in kerosene, I
>      pulled a few more layers of secondary winding.  Is the whole think
>      kaputt?  I'd hate to lose this NST, it was the only 15kV unit I
>      have/had.  I'd be happy with a 14kV, 90ma unit (shunt removal).  Is
>      there a non-obvious reason why pulling a few layers off the
>      secondaries would do anything other than reduce the voltage out?
>
>      Bwaahaahaa!
>
>      I, Arc
>
>
>
>

--
II*