Ping Vinnie (about resistors for your caps)

Posted by Russ57 (A) on May 4, 2007 at 07:42:40

Gingertube gave you the right info and you are going to have to determine the leakage values for your caps. I really hope you are using brand new high quality caps. I want to make it clear that the caps will only go downhill in specs once they are put into use and I am sure you want a long and safe life for your amp. With that in mind you want to be very conservative in your design. Heat is a big enemy so make the voltage sharing caps high wattage so they run cool and space them well away from the caps. The aluminum cased ones you can bolt to the chassis are something to consider. Don't forget that the outter cases of the caps will be live (high voltage)! Also remember the actual voltage the caps see is the combination of B+ voltage PLUS the AC ripple voltage.

For the first cap I'd use at least a 1,600 volt cap and not use series caps. You can get orange drops in a .033uF 1600 or 2000 volt rating. Put several of them together (not in series) to get where you need to be if one isn't enough.

I'll include a link for you to read. As you will find out you will either have to get info on your caps or do some trial and error stuff. Make sure to calculate wattage on the resistors. Make sure to consider what will happen if any given part fails, from one cap/resistor to a heater winding thereby reducing a major load. Personally I'd want the caps to handle the full voltage possible if the supply reverted to a cap input one (1.4 times secondary voltage). I'd want my sharing resistors to draw enough current to maintain critical induction if all tubes failed and there was no load at all beside the sharing resistors (which also function as bleeder resistors).

If you have no idea what critical inductance is, and/or find the math to size the sharing resistor too hard, I encourage you to seek help. Perhaps you can find a ham radio guy in your area? We really want you to be careful and safe (no darwin awards allowed!:)

Russ

cap info (Open in New Window)

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Topic - Ping Vinnie (about resistors for your caps) - Russ57 07:42:40 05/04/07 (1)

Re: Ping Vinnie (about resistors for your caps) - Vinnie 13:56:04 05/04/07 (0)

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