[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: (Fwd) bleeder resistors used with MMC



Original poster: "Peter Terren" <pterren@xxxxxxxxxxxx>

My first thought was : What is Bill doing making such a small coil? Is it a toy one for Xmas. Perhaps the Griffith Observatory (which you are doing if I recall) needs one for a small room like a toilet or broom cupboard?

Resistors for MMC have been debated many times. Some people don't use any. Most use a single 1/2 watt 10M resistor per cap. This has always worried me as it is way overvolting the resistors rating of perhaps 500 - 800 V but in this pulse application they don't seem to fail. Terry uses 4.7M x 2 per cap. I use 3.3M x 3 per cap. I don't think it has been proven who is right. My guess is it depends on the application. For home use they are probably not required for a small coil. For a reliable larger museum coil you need to minimise failure modes, so use 3 or more.

Peter
http://tesladownunder.com


------- Forwarded message follows -------
From:           Self <wysock@xxxxxxx>
To:             Terry Fritz <vardin@xxxxxxxxxxxxxxxxxxxxxxx>
Subject:        bleeder resistors used with MMC
Date sent:      Thu, 02 Nov 2006 11:07:53 -0800

Terry,
I've spent a lot of time surching the List archives and so far have
not found an answer to my question.  What would you recommend
as the best size (in megohms I would presume), and wattage level
to use with an MMC stack?  I just bought 12 of the CD-942's and
will be using all of them in series for a final cap rating of .012 mfd.

I know many folks have used resistors to equalize the voltage
distribution in these series strings.  Unfortuantely, I never saved
any of those posts to the List.  Any help or advice you can give
will be greatly appreciated.

Best regards,
Bill Wysock.
------- End of forwarded message -------