Re: Homemade caps vs. MMC's

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Craig Fuller by way of Terry Fritz <twftesla-at-qwest-dot-net>" <cbfull-at-hotmail-dot-com>

Thanks for the comments Terry!  I will try to get a photo of one.  After 
checking your links, I realize that the caps I have do not state whether it 
is an AC or DC rating.  I can only guess that it is an AC rating because 
they have handled so well.  I did take a look at the links someone posted 
about the "uno" MMC needing a home, and my caps look identical to those on 
the outside.  I can't see the markings on theirs though.

Maybe one day some engineer will figure out how to make very powerful and 
compact capacitors using PTFE or some other fluorinated polymer instead of 
polypropylene.  These polymers are well known for having considerably higher 
dielectric strength.  McMaster Carr sells fluorinated ethylene-propylene 
film by the foot, but it's kind of expensive for the typical basement 
tinkerer.

Craig

>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: Re: Homemade caps vs. MMC's
>Date: Sat, 17 Aug 2002 16:52:31 -0600
>
>Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>
>
>Hi Craig,
>
>At 05:34 PM 8/17/2002 -0400, you wrote:
> >Hi all,
> >
> >I have been using MMC's since my very first coil back in 1988.  Some guy 
>who
> >had his own electronics shop here in Ohio sold me two bags of 100 caps 
>for
> >10 bucks.
>
>One of the best deals I have heard of :-))
>
> >I had no idea at the time that they would be so useful.  They are
> >rated at .224uF and 1000V each, which is just perfect.  I can make a 
>string
> >rated at 45,000V and 0.050uF, and as I increase power, I just parallel
> >another string.  The best part is, after 20 minutes of operation, they 
>don't
> >even get warm!  I have looked for more on the net just to see how much 
>they
> >cost but I can find nothing to match.  What a lucky find.  Maybe I can 
>take
> >a picture of their markings in case someone would recognize the
> >manufacturer.  Anyone interested?  I don't have a website so you would 
>have
> >to put them up on your own.
>
>If you send me a picture I can probably figure it out or post it.
>
>terry-at-hot-streamer-dot-com
>
>You can also just get Cornell Dubilier type 942C.
>
>http://www.cornell-dubilier-dot-com/misc/h942.htm
>
>http://www.cornell-dubilier-dot-com/film/9421000.htm
>
>942C10P22K
>
>Richardson can get them eventually:
>
>http://www.rell-dot-com/
>
>http://catalog.rell-dot-com/rellecom/scripts/SkuPage.asp?SKU=84181&PNO=&PNM=
>
>They are $1.54 with a minimum quantity of 45.
>
>Geek group style 0.150uF 2000VDC may give a little more bang for the buck.
>
> >
> >Also, I never considered building my own from polyethylene and mineral 
>oil
> >because as a chemical engineer, I was pretty sure that the mineral oil 
>would
> >slowly permeate the polyethylene because of their chemical similarities
> >(like dissolves like, for those of you who have not taken general
> >chemistry), and eventually, almost certainly, cause the PE dielectric to
> >fail.  So I recommend that anyone looking for a cap to use on their coil,
> >save yourself the frustration and don't risk using the classic homemade 
>cap
> >recipe.  Just  look for suitable caps to make a MMC.  You won't regret 
>it!
> >
> >Craig
> >
>
>I have not heard of anyone making poly caps in a long long time now :-))
>
>Cheers,
>
>	Terry




_________________________________________________________________
Send and receive Hotmail on your mobile device: http://mobile.msn-dot-com