Everywhere I've seen a tube- (triode-) based constant current source schematic, the value of the grid bypass cap is ALWAYS 0.1 uF. I have never seen this value explained or calculated...
So, can someone explain what happens if the value is doubled? (Yes I have a bunch of 0.22uF caps!!!) I have a feeling that I could try it out to see, but probably not hear or measure a difference. So does anyone know how to explain how this value is determined?
Thanks.
So, can someone explain what happens if the value is doubled? (Yes I have a bunch of 0.22uF caps!!!) I have a feeling that I could try it out to see, but probably not hear or measure a difference. So does anyone know how to explain how this value is determined?
Thanks.
Hi,
Go ahead and use the 0.22uF ... it's an arbitrary value just to keep the thing from oscillating.
Too low C, audible to supersonic oscillation and/or noisy. Too high C, risk of motorboating (depending on tube).
But you should know that triodes make bad CCS', because their Rp is so low compared to a pentode. But if you have a lonely triode section looking for something to do, it's better than a plain R, I guess
Cheers!
Go ahead and use the 0.22uF ... it's an arbitrary value just to keep the thing from oscillating.
Too low C, audible to supersonic oscillation and/or noisy. Too high C, risk of motorboating (depending on tube).
But you should know that triodes make bad CCS', because their Rp is so low compared to a pentode. But if you have a lonely triode section looking for something to do, it's better than a plain R, I guess
Cheers!
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.