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In Reply to: RE: What I have so far (picture) posted by PeterI on May 13, 2015 at 08:46:49
What sort of filament windings do you have on that 318-0-318 power trafo? If, by circumstance, a 5 VAC winding for a vacuum rectifier is present, you can voltage multiply it to obtain the negative bias (C-) rail.
Eli D.
Follow Ups:
Yes, the power tranny, being older, has 5V supply. Was going to use a (physically) small, low current tranny for the bias. I can also supplement the 6.3 VAC filament supply with an extra tranny, but probably won't need to.
But does overdrawing a 6.53VAC winding make the whole tranny work harder, hurting or limiting its ability to supply HV current? I always wondered that.Pete
Edits: 05/16/15
It's NEVER a good idea to draw more current from a winding than it's rated for. Buy a filament trafo with plenty of "stones" for the tubes. You can use the 5 VAC winding in series with the primary to boost the 318-0-318 winding up. :> D The HIPOT rating of rectifier filament windings is necessarily good., Voltage multiply the other filament winding to get the bias rail.
I'm uploading a graphic that shows what a multiplier bias supply looks like. You will need more stages, but for the few mA. of current needed, that's a non-issue.
Eli D.
nt
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