Re: Re. Home-brew Capacitors


Thanks for the interesting reply.  Some quick questions:

1) Other than the heat seal "ruffles", do the Associated Bag Co. bags
appear to be relatively defect free - no pinholes or thickness variations?

2) How will you easily have 3 sheets between plates?  Foil in bags = 2
sheets between.  Another empty bag sandwiched between = 4 sheets between
plates.  Are you cutting additional bags into halves for the single 3rd
sheet, just using poly sheeting, or is every other bag actually a bag
inside a bag?  Why did you decide on 3 vs 2 sheets?


> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re. Home-brew Capacitors
> Date: Tuesday, December 15, 1998 5:09 PM
> Original Poster: Gary Lau  15-Dec-1998 0827 <lau-at-hdecad.ENET.dec-dot-com> 
> >Original Poster: "Steve Young" <youngs-at-konnections-dot-com> 
> 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