2N3954 / Moog 952

[Don Tillman]

   Date: Fri, 16 Jul 1999 20:41:04 +0200
   From: Hallgeir Helland <hhelland at mailandnews.com>
   Hullo,

   Can anyone recommend to me a replacement for the 2N3954 that
   I need in my Moog 952 clone? It seems to be a dual Fet transistor,
   but I'm not really shure what it's function in the circuit is.
   Looks like a differential amplifier maybe? I honestly don't know.

It's a dual FET wired as a pair of source followers for increasing the
impedance of the 741 voltage follower stage.  This was a reasonable
thing to do back when the 741 was about the best opamp you could buy,
but nowadays you'll get much better performance if you throw away the
FETs and replace the 741 with a high impedance FET opamp with a low
offset voltage  -- an LF411, LF412 or whatever your personal favorite
is.  Heck, all those opamps in that circuit should be replaced with
LF412s. 

  -- Don