Re: oil for caps (fwd)

From: 	Adam[SMTP:absmith-at-tiac-dot-net]
Sent: 	Monday, January 05, 1998 2:06 AM
To: 	Tesla List
Subject: 	Re: oil for caps (fwd)

>>Definitely not so! Ask anyone who has used the Sunsil refrigerator
>>compressor oil, it doubles the capacitors value. Look in the archive there
>>was a big discussion on it several months back.

>What are we doing here creating new physics? The capacitance may increase
>with higher dielectric oil but only because of the space being displaced
>between the foil and the poly. This may make a higher capacitance but it has
>to lower the breakdown voltage by stressing the poly more. You just don't
>get something for nothing. I remember seeing the posts about doubling
>capacitance, but I don't believe it.

I also think it may be exaggerated.  The only case where I can see the 
oil actually doubling the value of the dry cap would be if it was 
_really_ loose and sloppily rolled.  Thus, you would have oil filling up 
substantial air gaps and increasing the capacitance.

But, consider this mechanism:  The cap is not rolled super-tight, but it 
is not sloppy either.  You add the high-k oil and, over time, the poly 
absorbs some of it.  The poly increases in k due to the absorbed oil, 
swells, and also (due to swelling) presses more firmly against the plates 
displacing air and tightening the roll.  The combination of increase of k 
and increase in "tightness" should give the cap value a significant 
boost.  I would not expect a doubling, but I've honestly never tested 
sunsil-saturated poly to see what its dielectric constant really is.

Just my $0.02


Adam Smith
Epoch, Inc. Digital Music Project

www.tiac-dot-net/users/absmith/                 MP3 Demo Tracks Now Available!