Using operational amplifiers of the time, we found this circuit in documentation from the 90s. The configuration can be adapted to use modern operational amplifiers.
Old phones with dials can be used in a simple home intercom system, as this circuit from Popular...
This circuit was found in the July 1992 issue of Radio Electronics magazine. The circuit has a...
This simple circuit indicates if the polarity of a load is reversed when it is connected to a...