This circuit for light modulated in frequency (FM) operating at 50 kHz was found in a 90’s Electronics Now. The circuit has an active filter. Modern equivalent transistors can be used.
Found in General Electric and 1967 documentation, this circuit automatically turns off the...
This amplifier stage without an output transformer was found in Radio Electronics magazine from...
Found in an Electronics World of 1968 this circuit can use current SCRs and the diodes are...