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Re. Home-brew Capacitors

>Original Poster: "Steve Young" <youngs-at-konnections-dot-com> 
>
>Hi all,
>
>1) It's been a while since posts have been made about proposed home made
>dry (no oil) caps made by connecting a bunch of them in series to minimize
>corona and breakdown in the individual sections.  Has anyone achieved good,
>long life results yet?  If so, many of us would appreciate the particulars.
>
>2) It's also bee a while since the list had posts of plans to build caps
>using stacks of poly bags (e.g. from Associated Bag Company).  Has anyone
>done it, and if so, what were the results?
>
>Bottom line - building caps is a major undertaking.  If people discover
>better ways to do it, please share.
>
>--Steve

I was one who proposed a dry construction capacitor by building a 20
series element flat plate unit.  I have purchased 1000 13" x 13" x 2.0
mil bags from Associated Bag Co for $29.20 plus shipping.  This was
actually the price for the 1.5 mil thickness, but since they were out of
that, substituted 2.0 mil (actually 1.875) for the same price.  I plan on
having three 2-mil thicknesses between plates.   Using 13" wide bags was
essential so that 12" wide Al foil could be used.  Unfortunately due to
space constraints in my rig, I have to cut the length down to 10", which
for the necessary 760 bags, is a LOT of cutting, even on one of those
gillotine-type paper cutters.  I'm somewhat disappointed in the bags I
received.  They were packed in a box smaller than 13" square and
consequently were folded and creased.  Also, the bottom of the bag is
heat-crimped and is a bit ruffled, making the stackup uneven.  I'm
presently trying to find a good way to build each of the 20 units as a
modular assembly that won't shift around as it's moved and bolted into
the 20-unit stack.  I also plan to incorporate 6Meg balancing resistors
in parallel with each element, and these are complicating the assembly.
One thing is for sure, it will be a lot more work than a rolled poly cap.
I promise to post results, good or bad, as they occur.

Regards, Gary Lau
Waltham, MA USA