This 12.5 W quasi-complementary amplifier was found in a 1969 General Electric publication. Note the high supply voltage. Transistors are common types at the time.
This operational amplifier circuit with variable gain was obtained in an 80's Electronic...
The circuit shown was obtained in American documentation from 1968. MOSFETs can be replaced by...
We found this circuit in a Popular Electronics from the 80s. This circuit eventually doesn't work with...