Re: CONCERTINA CAP

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

Original poster: "Black Moon by way of Terry Fritz <teslalist-at-qwest-dot-net>" <black_moons-at-hotmail-dot-com>


Iv used the extended foil method, works very nicely, and makes really big 
connectors even with just tin foil, Common 2l pop bottle plastic cut from 
the center flat part seems to work quite nicely.
Makes a very dence (1" round 7" across) 4nf to 6nf iirc cap
(depending on how wrinkled the foil is, also you can add about 0.5nf by 
wraping electrical tape around it as tightly as you can)
Id rate em good for 5~10kv myself.
I cranked em up to 20kv (it started flashing over the 1cm spaceing at the 
edge of the dielectric) and they seemed to be fine for a few mins aside 
from the odd flash inside the cap, that really seemed non distructive (tho 
a larger system might, I really don't suggest subjecting em to internal 
flashover)
tho, when I took one apart, it was apparent the pop bottle plastic had 
sorta goten stuck to the tin foil, and had changed color abit (I use the 
clear pop bottle plastic, never tryed the green stuff)
Note, they have kinda horrable self discharge and charge recovery
iv 'shorted' em
then a min latter goten a small shock from the charge recovery
I now short em for 60 seconds befor considering them safe to handle
Never added any oil, personaly as they only took about 5 mins to make each 
and cost about 23 cents each (deposit on the bottles that you can't get 
back mainly) I don't really mind if they fail :)
Plus, if they fail they arnt gonna spray oil everywhere and as they arnt 
sealed I doubt they would expload
Catch fire mabey, but I doubt they would expload.
If your worryed about life, just use em at lower voltages (5kv or less)

>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: Re: CONCERTINA CAP
>Date: Tue, 08 Jul 2003 17:57:07 -0600
>
>Original poster: "Crow Leader by way of Terry Fritz <teslalist-at-qwest-dot-net>" 
><tesla-at-lists.symmetric-dot-net>
>
>If you are worried about inductance of a rolled cap, you can just wind it
>extended foil style. Have the edges of the foil or metal stick out on both
>sides way past the dielectric. You can them bolt them together eliminating
>current from having to spiral around inside your cap to get to the
>terminals. It's a bit harder to wind a cap this way, but makes for solid
>terminations. My homemade caps tended to fail by the insert tabs used to
>terminate the internal foils.
>
>KEN
>
>On Tue, 8 Jul 2003, Tesla list wrote:
>
> > 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.
> >
> >
> >