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Re: flashing vs. whatever


From: 	Alfred A. Skrocki[SMTP:alfred.skrocki-at-cybernetworking-dot-com]
Sent: 	Thursday, November 27, 1997 1:31 AM
To: 	Tesla List
Subject: 	Re: flashing vs. whatever

On Sunday, November 23, 1997 7:11 AM Barton B. Anderson
[SMTP:mopar-at-mn.uswest-dot-net] wrote;

> To all, a question for rolled polyethylene caps.
> I'm getting ready to begin plans for building these caps. My transformer
> matched cap value is .256uF. I'm planning on building three .083uF caps
> to achieve the (near) value. The plate area required is 2592 sq. inches
> (18" x 144"). I also plan on using four 4 mil sheets each side of plate
> for total of 8 between plates. In transformer oil the caps should prove
> durable assuming I get the air out.

I might recommend that you consider a stacked plate capacitor instead of a 
rolled cap. The advantage the stacked plate capacitor has is that it is 
much easier to assemble and much much easier to eliminate bubbles in by 
mounting on edge. I have built several rolled type polyethylene capacitors 
and even when mounted on end it is very difficult to eliminate bubbles.
A technique that has become popular for eliminating bubbles is to put 
oiled kraft paper between every sheet of aluminum and every sheet of 
polyethylene.

> It seems those of you who have built this type of cap have used roof
> flashing. I'm not real familiar with roof flashing, but isn't it a bit
> thick for the purpose? At least the pulse caps I've seen have an
> extremely thin aluminum sheet. What advantage wood roof flashing give
> over say aluminum wrap bought at a grocery store?

The only advantage that roofing aluminum has over aluminum foil is that it 
is easier to connect to solidly. BTW if you do make the rolled type 
polyethylene capacitor DON'T use a small tab at one end of the foil to 
connect to, use the entire length of the foil for your electrical 
connection otherwise you can create a time delay problem within the 
capacitor.

 
                               Sincerely

                                \\\|///
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                           Alfred A. Skrocki
                   Alfred.Skrocki-at-CyberNetworking-dot-com
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