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Re: Homemade Caps

Original poster: "rheidlebaugh by way of Terry Fritz <twftesla-at-qwest-dot-net>" <rheidlebaugh-at-zialink-dot-com>

Winston: I'll continue with my answer. This is how my students and I make
capacitors. I make my caps larger and higher voltage with about the same
capacitance we use 15/60 NTS power which puts about 22kV on them. We have
had no problems. We use a paper cutter, paper punch, pop rivite gun, and
heat sealer as tools. The plates are 10" flashing 6 x 10 cut from a 10'
role. and 4 mill LDPE bag stock making 3.5 nF each and we use 4 each
parallel sets. we cut the flashing into 19 plates and the last plate is cut
into 1" straps. The last plate is never a full 6" wide. Each set of plates
has 2 straps on each end for a total of 4 straps to carry current. I connect
them with 1" pop rivets and 2 al washers between each plate as spacers. I
make 19 ea 6 x 12 double thick bags sealed 2" from the bottem to hold the
plate position. I cut a "V" 3/4" deep in the top of each bag center to clear
the pop revet. A 1" pop revet is only long enough for 1/2 of the plates so
it takes 2 to connect all the plates on one end. after punching all the
plates and all the straps with the paper punch in the center of one end 3/4"
in. I cut off all sharp corners off about 3/8" deep. I place each of the
plates in one each double thick bag. I then roll 6 turns of 12" x 4mill bag
stock double thick around the first plate then I put one plate on each side
facing open end opposite the first and wrap 6 more wraps adding alternate
plate pairs after each 6 wraps untill all used up. I then wrap 12 turns as
the last wrap. I use nylon cord to hold every thing tight with 3 tie
strings. I then slide the plates slightly out of each position to connect
the straps, washers, and plates together with the pop rivet and then slide
them back in. Finding a plastic container is the hard part. I seal 2 sets of
plates in a plastic container of mineral oil ( about 3 gal) and seal the lid
on with silicon RTV caulk. Each set has 19 plates over lapped 6" x 8" with
12 layers of 4 mill LDPE or 12 mill total thick to give 4 sets of 3.5 nF for
14 nF total. Leave a slight vent as air pressure is releaved when you first
start using the cap. This stops after all the air in the oil out gasses.
Some of my students package the caps seperately. One of my students "Josua"
uses empty plastic coco cans re painted. They look factory made, his work is
good, and his TC's work very well.
   Robert H       

> From: "Tesla list" <tesla-at-pupman-dot-com>
> Date: Tue, 07 May 2002 18:21:25 -0600
> To: tesla-at-pupman-dot-com
> Subject: Homemade Caps
> Resent-From: tesla-at-pupman-dot-com
> Resent-Date: Tue, 7 May 2002 18:48:05 -0600
> Original poster: "Marry Krutsch by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <u236-at-earthlink-dot-net>
> Hi All.
> Sorry to dredge this up again, but I'm still unsure about
> construction/materials for my new cap.  I've been thinking about making
> a paper/oil and Al flashing, or oil and flashing cap.  Which is least
> lossy, and least likely to fail?  I plan on running it at 21 kV or more
> (although in reality, it probably won't see more than 18kV), so how
> thick should the dielectric be?  I'm going to use a 50 cal. ammo can for
> an enclosure.  Each should yield 15-25 nF (depending on design).  I need
> a total of 100 nF (two different PSU's for my coil), so this will take a
> while :-(.  At least I can get materials at low cost.
> Also, how can I "torture test" on of these without running a coil with
> it?  I think simply hooking it up to a xfmr with a sparkgap would work,
> yet would be very hard on the power supply.  Any suggestions?
> Any input is greatly appreciated.
> Winston