This circuit was found in an English publication from 1967. The circuit is for listening on a phone. Transistors are types of germanium of the time.
This didactic circuit from a 1977 Radio Shack documentation shows how to use the 741 as a...
This circuit from the 80's can be easily implemented but needs some changes to avoid problems with...
Found in a 1967 General Electric documentation, this circuit generates a ladder signal from...