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.
Found in a documentation from the 90s, this circuit limits and amplifies a voice signal in the 800...
This circuit was found in documentation from the 90s. The operational amplifier is NE5514, which is...
We found this circuit in the August 1970 issue of Radio Elecronics magazine. It uses the CA3018...