Re: Homemade Rolled Caps

In a message dated 96-02-27 12:23:45 EST, tesla-at-grendel.objinc-dot-com writes:

>I didn't make a clean room, but I did set up a special 8 foot long work 
>bench for assembly.  All aluminum flashing edges were sanded down smooth, 
>and afterwards both aluminum and plastic got wiped down thoroughly before 
>assembly.  No carpet fibers, hair or small children got rolled up.
>I am going to tear down all my failed poly caps and rebuild them into a flat

>plate capacitor.  I'm going to mount the plates in a pole pig housing that I

>just gutted.  I'm going to to use multiple sheets of poly to make 120 mil 
>dielectric, and I'm assembling it under oil, sheet by sheet, to eliminate 
>air pockets.  This will be the last poly cap I build - I'm going to buy 
>commercial caps from that point forward.

When I built mine, I also was very careful.  Sanded all the edges, cleaned
all the materials, layed everything out on clean paper, etc. - but they still
failed.  Possibly the problem is with the dielectric and scratches,
imperfections, etc.  If someone was planning to build a home made rolled cap
I would certainly reccommend two layers of .030 poly instead of one .062
layer.  Three layers of .030 would be best, of course the capacitance
produced would be less.

Ed Sonderman