Re: Hints on building a .08uf cap?

From: 	richard hull[SMTP:rhull-at-richmond.infi-dot-net]
Sent: 	Tuesday, July 15, 1997 2:41 PM
To: 	Tesla List
Subject: 	Re: Hints on building a .08uf cap?

At 07:19 AM 7/15/97 -0500, you wrote:
>From: 	Steve Falco[SMTP:sfalco-at-worldnet.att-dot-net]
>Sent: 	Monday, July 14, 1997 3:43 PM
>To: 	tesla-at-pupman-dot-com
>Subject: 	Hints on building a .08uf cap?
>I have switched from a 12kv 30ma neon (which I toasted) to the H&R
>copier trannies.  I now need a lot more capacitance than the .005 uf I
>have.  Skip Greiner suggested .08 uf worked well with these trannies.
>My question is, should I build lots more rolled caps in 6" PVC pipe
>(like 10 more???) or should I build fewer, higher capacitance units?  I
>don't know how much capacitance I can get into a piece of 6" pipe.  I
>used .093" LDPE in the first cap, with plates about 42" x 14".  I might
>be able to get 90" x 14" plates into the pipe, but this still will not
>get me more than .0125 uf or so per unit.
>Am I better off building flat plate caps?  Would I use heavy aluminum
>foil rather than the flashing I used in the rolled cap, to make
>terminating all the sheets easier?  And lastly, how many caps should I
>build?  Just one huge one, or perhaps four smaller ones?
>	Thanks,
>	Steve Falco
>	sfalco-at-worldnet.att-dot-net

You question is a good one and deserves a good answer.  The answer is to buy
a custom built job from one of the big capacitor houses!

The original large rolled capacitors we championed years ago was to get the
advancing novice coiler moving from their first very small systems to
small-medium systems.  At this point the novice is ready to expand, but
still not committed to coiling and cost is still of extreme importance.

Beyond about .03ufd, the large number of large homemade rolled capaciotrs
capable of withstanding higher voltages becomes cumbersome and expensive.  I
have seen a number of coilers build 6 or even 8-10 of our original .018ufd
units to get more voltage and or capacitance.  We never built more than 4,
ourselves!  The turn around is reached at 4 units I think, and it is time to
move on to custom made units constructed by professionals who do this for a

You should keep your eye peeled constantly at hamfests and in surplus sales
catalogs for surplus bargain priced pulse capacitors.  Otherwise, you will
have to contract with a custom house for the construction of a special cap
suited to your needs.  Expect to pay about $500.00 for a .08ufd rated at
30kvac (60 KVDC) pulsed service with a rep rate of 500-1000pps.

If you decide to go the multi-capacitor, home built, route keep a close tab
on the costs of time and materials.  You will be amazed how fast it adds up
and many hours you will sink into the project, not to mention the large area
or floor space needed to house the homemade unit. (one that will really

Also, if you go homemade, abandon the flashing and move over to very heavy
foil.  use thinner dielectric .010 or .020 (polyethylene or polypropylene)
and make much large unit rolls (.1ufd to .2ufd).  Series a large number of
these units to achieve voltage and proper capacitance.  You'll still need
lots of oil and containers.

Good luck

Richard Hull, TCBOR