In Reply to: CCS as screen regulator ? posted by pipo on January 6, 2006 at 09:15:50:
Not that long ago I helped a guy working on a pp807 with vrtube regulated screens. He was having the same problems I had when I tried using gary's ccs feeding vr tubes for POWER pentode screens. It motorboats. Screens might be too capacitive or something. (I believe that's the concept of how screens isolate plate from grid, capacitors in series or the like, but I might remember wrong).
The ccs/vr tube combo works fine for signal pentodes, sounds great.
An idea I had later, and never tried was using the mu-follower output to drive the screens, essentially turning the regulator from a shunt to a series pass. Isolating the screens from the vr tubes at constant current should provide VERY stiff regulation.
The pp807 guy never tried it though, he went to zeners.
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Follow Ups
- Good in Theory, No luck implementing - ottoamps 15:24:35 01/07/06 (2)
- Tell your friend to do this, by all means! - drlowmu 16:56:27 01/07/06 (1)
- wow, I think monkeys are flying out of my.... - ottoamps 21:24:56 01/08/06 (0)