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previous: ken gilbert ok. i'm starting to pursue doing m... -- 5/19/2000 4:21 PM

Re: positive feedback musings...

5/19/2000 8:53 PM
ChrisM	Re: positive feedback musings... I don't think this is going to achieve what you want. Positive feedback is very tricky and almost always results in nasty oscillations and whatnot. I think the highest stable gain you could get would be from a common cathode without degeneration. Since you would be adding degeneration at the cathode, and tapping some of the output signal to be fed back into the grid, I think you would lose gain, and just induce oscillations. Maybe there is some way to make this work so the signal degredation of the system balances the positive feedback and results in a stable output, but if there is, it may be very dependent on varying factors such as tube gm, input signal amplitude and frequency, wire placement, and maybe even temperature & humidity. I don't think it will work frankly, but if you try it and succeed, you'd get a whole lotta respect from me. (not that I don't respect ya now). -Chris

5/19/2000 8:53 PM

ChrisM

Re: positive feedback musings...

I don't think this is going to achieve what you want. Positive feedback is very tricky and almost always results in nasty oscillations and whatnot. I think the highest stable gain you could get would be from a common cathode without degeneration. Since you would be adding degeneration at the cathode, and tapping some of the output signal to be fed back into the grid, I think you would lose gain, and just induce oscillations. Maybe there is some way to make this work so the signal degredation of the system balances the positive feedback and results in a stable output, but if there is, it may be very dependent on varying factors such as tube gm, input signal amplitude and frequency, wire placement, and maybe even temperature & humidity. I don't think it will work frankly, but if you try it and succeed, you'd get a whole lotta respect from me.
(not that I don't respect ya now).

-Chris