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.
In the figure we show how to use a varicap to modulate a signal in frequency. The circuit can be...
Found in Datel's documentation from the 1980s, this circuit makes use of the company's operational...
This circuit can function as a simple shield converter from BCD to analog outputs. The circuit...