This circuit for multiple sound inputs was found in a Radio Electronics from January 1992. It consists of a Bargraph connected to a multi-input mixer.
This simple circuit for switching RF signals was found in an RF Design from the 90s. The circuit...
I found this circuit in a Popular Electronics from 1992. The circuit can be easily implemented with BC549...
This circuit was found in a 90s EDN. Its purpose is to increase the efficiency of operational...