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Old 27th Jun 2017, 5:10 pm   #212
mark_in_manc
Octode
 
Join Date: Nov 2011
Location: Manchester, UK.
Posts: 1,872
Default Re: 807 (maybe) amplifier build. Now EL34

I never got my head all the way round this.

I could work out the complex transfer function of a passive network with no feedback in terms of the ratio of two big polynomials in (jw), and plot it as a Bode plot, or Nyquist plot, or pole-zero plot, or whatever. If it had some (complex) gain I could build that in too I guess as a multiplier to the numerator of that big fraction. I think I understand about interpreting a Nyquist plot to try not to 'envelop' the (1,0) location, but to what does that plot pertain - the gain from input, right round the loop back to the point where the feedback would be re-injected, but with the loop broken at that point?

I think my confusion is that I don't know how I would write those polynomials down if the loop were closed.
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