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Re: Build own capacators



Original poster: Terry Fritz <vardin@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Dave,

At 06:08 PM 12/16/2005, you wrote:

What is the Voltage when corona first appears ? (in air ), if a person wanted to make a 'dry' cap ,.. maybe 900-1000 volts ????

For polypropylene it is about 315 volts. The CD MMC caps are actually two caps in series internally, so they are rated twice that at 630VAC. That is why you always see 630VAC all over the place for poly caps.

My rolled caps got alot of use the first year or two after I made 'em, then sat around alot after that. I did have a couple of failures ,.....#1 experimenting with a SYNC rotary, ....#2 , I was dorkin around with a small coil with a 12/30 neon. Not sure about that one, before that, I ran them caps daily for weeks at 5kw with my 8" coil in da basement , with a rotary,....repair was 'FAIRLY' easy both times, the burn through was only about 3-4 turns in from the out side,....I just unrolled , place a poly patch over da hole, and re-rolled, kinda messy, but the cap was up and running within an hour or so.........Yes, Im a bit antiquated ,....;-) ,.......I still play ( Records/LP's ) too ,... , but, I used glass plate caps in air(nice glow ) on my first few coils, .rolled poly was a big improvement for me

I don't think an MMC will perform noticeably better than a nice rolled cap. They are both "so good" electrically that I think any difference would not be very noticeable between them. Of course MMCs have other nice advantages. But if you looking for better performance only, the MMC should not matter.

Cheers,

Terry