Re: rolled caps (fwd)

---------- Forwarded message ----------
Date: Tue, 28 Apr 1998 18:39:47 -0500
From: Jeff Corr <corr-at-enid-dot-com>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: rolled caps (fwd)

>"Regarding your rolled up caps -- when you roll the caps very tightly you
>compress the dielectric thus reducing it to 1/2 its normal thickness.  "
> Sorry, don't believe that at all!  The normal dielectric
>materials are almost uncompressable.....  Seems to me that any such
>capacitance increase is due to the fact that both sides of the plates
>"see" another plate, almost doubling the effective AREA.

I must agree.  The preasure required to compress poly would not be
attainable when dealing with 90mils of rolled poly.  It would be like
trying to fold a piece of paper in half more than 12 times... 

When dealing when rolled caps, I must wonder, does the action of rolling
the cap in itself actually MORE than double the capacitance.  Sure, you
have two plates seeing each other, doubling the capacitance, but would an
inner layer in the roll "sense" the above layer directly above it, and off
a small percentage to the sides? 

My rolled cap lying on the floor waiting to be rolled only measured
.00004uf...  once rolled...  .01256uf...  Obviously lying on the floor
didn't make the plates touch very well, and there was not oil in there... 
just point out the weird stuff I notice :-)