On 12/14/2011 08:14 PM, Mouse wrote:
  On the other, I'm considering an AGC circuit that
doesn't use a bulb,
 but instead uses a FET as a variable resistor, and trying to figure out
 where it's got anything nonlinear in it (assuming the amplifier is
 running class A). 
   Jim Williams (RIP) did a LOT of research on this.  The bulb
outperformed the FET by a gigantic margin. (just sayin'..)
   That's a fascinating read; I'll try to find a pointer if you're
interested. (I have the saga in a paper book, "Analog Circuit Design:
Art, Science, and Personalites", one of my favorite books)
   I am sure we
all know the stroy of Fred Terman and a certain research
 student. 
 Doesn't sound familiar to me, for what that may be worth. 
 
   I'll let Tony wax poetic about that. :)  That was my reference to the
incandescent bulb.
              -Dave
--
Dave McGuire
New Kensington, PA