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Re: Cap problems (fwd)
---------- Forwarded message ----------
Date: Tue, 25 Feb 1997 12:24:41 -0500
From: Julian Green <greenj-at-swlogica.demon.co.uk>
To: mod1-at-pupman-dot-com
Subject: Re: Cap problems
>Date: Mon, 24 Feb 1997 20:22:50 -1200
>From: Ken Smith <ksmith-at-ihug.co.nz>
>To: Tesla List <mod1-at-pupman-dot-com>
>Subject: Cap problems
>Hi,
> Help please :
>
>I have hit the wall with capacitors. I have received several designs for
>rolled caps from individuals and gleaned all that I can from the 'net.
>However I am stuffed since I cannot find Al flashing here in NZ at all. The=
>y
>just don't use it (as far as I can tell - and I have looked hard - believe =
>me.)
>
... snip ...
Well I dont have any al flashing either, so I used cooking foil instead.
My cap is 0.03uF with 40 mils of poly between the plates and works very
well
on 11KV. Coaxial design.
When constructing the cap using foil it is very important to ensure a
good
connection along the entire length of the foil if self inducance and
resistive losses are to be reduced. The way I achieved this is to allow
the edge of the foil plates to extend beyond the poly down the length
before
rolling. After rolling the foil forms two terminals at each end.
I roll my cap around a lenght of copper water pipe which has been
insulated over nearly all its lenght except for the ends (wrap poly
around the pipe and stick down with tape). One foil end can then be
clamped down to make contact with the bare end of the pipe using a
hose pipe clip. The other end clamped down using a second hose pipe
clip, but clamp down on a insulated section of the pipe.
Connection straps can be slipped under the clip before tightening.
The whole thing is then put into a length of PVC pipe caped at one end.
Fill with oil and pump down to extract any trapped air.
Julian Green