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Re: (Fwd) bleeder resistors used with MMC



Original poster: "resonance" <resonance@xxxxxxxxxxxx>



Better to use Allied Electronics pulse rated resistors --- 3.5 kV working voltage. Only 55 cents each.

Although, I have never used any bleeder resistors in my AC NST powered coils --- and have not found any holding a charge --- at least not in the past 6 years!

Dr. Resonance

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