Suggested by a 1968 Motorola power semiconductor manual, this circuit uses a special transformer and transistors from the era. The frequency is 60 Hz.
We found this circuit in a 1974 integrated circuit manual. Operational amplifiers can be of...
We found this circuit in American documentation from the 1980s. Transistors can be of general use....
This sophisticated remote field strength meter circuit was found in a 73 magazine for radio...