Found on a 1964 CQ this circuit is intended for tone frequency change modulation (FSK) telegraphic transmissions. It operates with signals of 2.975 and 2.125 Hz.
This simple diode test appears at other points in this section. Or circuit can be adapted to use...
Found in Electronics Now magazine in an issue from the 90s, this circuit is different from the...
This circuit inverts the phase of an audio signal, maintaining its intensity. The transistors can...