Re: homemade rolled cap

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Jim Lux" <jimlux@xxxxxxxxxxxxx>

Assuming that you want to do this because of historical curiousity..I
haven't priced it out recently, but I suspect that it's actually cheaper to
build a MMC for a given voltage and capacitance than it is to buy all the
components for a rolled cap.  You can't just whip on down to home depot and
buy a roll of 4mil plastic sheeting and some aluminum foil, roll it up and
stick it in some sort of cheap vegetable oil and expect very performance or
reliability.  If you're real low budget, the beer bottle in a bucket of salt
water is probably the way to go.

Key things on rolled caps..
- Use multiple thin layers of plastic, not one thick layer. That way, a
defect in one layer doesn't kill the cap.
- You must keep the assembling area scrupulously clean.  Tiny dust
particles, etc are what lead to failure
- You need some way to pull a vacuum on the assembly after you immerse it in
oil.  Air bubbles in the middle of the roll lead to field concentrations
which lead to failure.
- Attaching to the aluminum sheets is the tricky part. Spot welding is best.
- speaking of which, you need to find some suitable aluminum sheet for the
electrodes. Several mils thick would be good, because you need enough
dimensional stability to not wrinkle or deform while you're rolling.




----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Thursday, February 24, 2005 6:40 AM
Subject: homemade rolled cap


> Original poster: Bobby Amaya <dimon20042004@xxxxxxxxx>
>
> Hi everyone,
>
> Can anyone tell me how to build a good high
> voltage(40+kv) rolled cap that is not extreemely
> expensive?
> Bobby,
>
> =====
>
>