[sdiy] Wanted: Discontinued Op-amp (alive)

[Mike I]

Datasheets for Raytheon RC4739  Fairchild uA739 and Motorola MC1303 can be
found at www.datasheetarchive.com

They are all quite different ... and ancient... late 60's early 70's.  As
far as I can tell, Raytheon released the original 4558 dual op amp (the
RC4558) after the 4739. The internal schematic is very similar to the 4739.
Probably in most applications retrofitting a 4558 (or a more recent audio op
amp) will yield better noise performance than the 4739. Don't do this
blindly though, or you might end up with HF oscillations etc. Probably best
just to save 4739's for repair purposes.
M.