15 Dec
2011
15 Dec
'11
3:24 p.m.
On 12/15/2011 05:13 PM, Tony Duell wrote:
I thoguht in the end he amanged ot get the FET cirucit to be better than
the light bulb, but it took a lot of work (and probably wasn't worth it).
No. His initial attempt with a FET didn't perform all that well (if
memory serves), but in the end his very complex circuit with (I think)
three high-end opamps and an LED-driven photocell did end up
outperforming the incandescent lamp design.
I shall have to obtain a copy of this book.
-Dave
--
Dave McGuire
New Kensington, PA
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)
YEs, a great book. Along with Bob Pease's book ('Analog circuit
troubleshooting' or soemthign like that). Well worth reading.