Re: CONCERTINA CAP

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

Original poster: "Jolyon Vater Cox by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>

Ian.D,
I have actually made a "concertina" cap
lots of poly-pockets (document covers) stacked up to make the dielectric ,
plus whole lengths of aluminium foil cut along the length of the roll to
make the capacitor plates -which are woven in and out of the poly-pockets at
90 degrees to each other to keep them apart; Whether I'd do it again is
another matter as keeping all the polypockets straight as the plates are
woven in and out (I used 6 poly-pockets  between conductors) is hard work
and time consuming!

The cap is  composed of four sections of 22nF
in turn these are composed of 132 polypockets - that is, there are 22
parallel "cells",each of 1nF, to each section.
as it turned out, 6 pockets between plates was insufficiently reliable  for
the voltage used (30kV or so from DC-rectified ignition coil) when all four
sections were connected in parallel for 88nF so   the sections were
connected in series-parallel for 22nF instead.

Given the time and patience it takes to make
-plus the weight of the capacitor  -mine is the size of a large shoe box and
weighs almost as much as a small TV (never mind, it's more compact than the
eight 2-litre pop-bottle salt-water capacitor  it replaced!), you might
prefer to try using an MMC or something else.
On the other hand if you have lots of time and less money, and are prepared
to put up with risk of premature failure, the concertina cap might be worth
a try.

Jolyon.

   ----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, July 08, 2003 2:40 PM
Subject: CONCERTINA CAP


 > Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>"
<IanHelixsp-at-aol-dot-com>
 >
 > First of all hello everybody, this is my first correspondence to the
'list'.
 > I am in the process of building my first coil (4 1/2") and after searching
the
 > W.ibbly W.obbly W.ay I discovered this fantastic information resource. I
was
 > amazed to see so many 'insane' people out there with the same inexplicable
 > fascination with electrical discharges. Perhaps I'm not that mad after
all?
 > Anyway I'll get to the point. With respect to rolled caps having self
 > inductance
 > and long discharge paths, I was wondering about folding i.e. a concertina
cap.
 > I know that the effective capacitance would be half that of a roll for a
 > given length of material, but the discharge path would be very short and
 > very low
 > resistance (one could run the bus-bars right along the exposed ends or
loops.
 > The reason behind my thinking is as follows. I work as a buyer for a
roofing
 > company and we carry large quantities of self adhesive allu. flashing and
 > rolls
 > of thick (up to 2mm), poly roofing membrane, p.v.c. pipes of all diameters
 > etc. so my plan was to burnish down the allu flashing to the poly membrane
 > excluding all the air. Then when folded the only place air can be trapped
is
 > between plates of the same polarity. Why not just build a stacked plate
 > cap? I hear
 > you cry, well.....I am I just thought this would reduce production time
and
 > make it easier to exclude air. It's just a thought.
 > Any comments anyone?
 > Also I don't seem to be able to find any detailed info on d.c. resonant
 > charging or magnifier coils and I'm struggling to find a suitable
 > transformer as
 > nst's are limited by law in the u.k. to 10kV -at- 60mA and also have internal
 > trip
 > switches for earth leakage and or short circuit (or so I'm told by
somebody in
 > the industry), pole pigs are very rare. (except those 33kV jobs that weigh
as
 > much as a car and cost as much as a house!) I know I can series two mot's
but
 > that's still only 4kV.
 >
 > Ian D, Liverpool, U.K.
 >
 >
 >