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In Reply to: RE: I think my point of view and Henry's are still both correct... posted by kurt s on October 27, 2009 at 17:40:00
Thanks for the reply, but I don't think you really got the point of my long article. (IMHO it's a brilliant essay, but I never expected anyone to read or understand it, not then, not now -- though I would be delighted if they did.)
Here is a synopsis for the attention challenged: All the common triode circuit models are just abstractions of the tube that have no real bearing on the actual internal structure or operation. The internal NFB model is one such abstraction that does away with the series (Thevenin) or parallel (Norton) plate resistor and replaces it with an active control structure. It's no closer to the reality of how the tube works than the models it replaces. Furthermore, it gives no additional insight into externally observable behavior of the tube and its use in practical problems complicates circuit analysis. The model is based on circular logic and awkward assumptions. Finally, the underlying approach applied to other problems leads to feedback appearing in all kinds of devices where we don't normally think of it existing, like diodes, resistors, electric motors, and parachutes.
I'm not actually that committed to the argument, not like I was three years ago, but I couldn't resist Tre's invitation to dredge up a few thousand words of archived historical drivel.
-Henry
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