Re: MMC caps: prices, sources, and types

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

Original poster: "john cooper" <tesla-at-tesla-coil-dot-com> 

FWIW - the mmc in my bi-polar coil (9kv, 60ma xfr), has 12,500vdc, 
7500vp-p, series chains of Pan. ECW-H series caps (5 caps in series, each 
rated at 1500vp-p, 2500vdc).  It's never failed during repeated 8 to 10 
minute runs.

---------- Original Message ----------------------------------
From: "Tesla list" <tesla-at-pupman-dot-com>
Date:  Sat, 08 May 2004 10:54:18 -0600

 >Original poster: pepperman-at-softhome-dot-net
 >
 >I've been trying to price an MMC, but using the recommendations I've
 >generally seen (e.g. 3-4x the rated voltage of your transformer) I've been
 >having a hard time finding a good source.  Putting that many in series to
 >handle the voltage tends to mean you need more strings, which
 >significantly drives up the price.  I noticed that the Geek Group tended to
 >not use as many in their MMC, and it seems to perform acceptably.
 >
 >So what would you say the minimum combined DC voltage rating (as a
 >percent of the transformer voltage) is to have an MMC that will perform
 >acceptably and still have good reliability?  I'm not overvolting the
 >transformers on a variac, so that shouldn't be an issue.
 >
 >I'm also looking for a good source for the caps.  I know the Geek Group is
 >generally a very good source, but my time frame doesn't allow for the
 >delay it would take to get caps from them (they won't get another
 >shipment in until 5/31).  What other sources would you recommend for
 >good (and cheap!) caps?  And would any type other than the metallized
 >polypropylene caps still be acceptable?
 >
 >Finally, what would you say to expect to spend to put together an MMC
 >for a 1.5 kVA Tesla coil?  I'm not sure yet whether I'll be using 10 kV or 15
 >kV transformers, so unfortunately I can't specify.  I guess if 10kV, I'll be
 >trying to get 150mA, and if 15kV, I'll be trying for 90mA.
 >
 >Thanks for your help!
 >Michael Johnson
 >
 >
 >