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.
Two inverters of a 4069B type CMOS integrated circuit form this oscillator which is characterized by having...
Raytheon's used operational amplifier is rare today, but the configuration can be adapted to use...
Found in a radio amateur magazine of the 1980s, this circuit uses components that can still be...