This converter has coils according to the reception and converted frequency bands. We found it in the October 1989 Radio Electronics magazine in an article that teaches its construction.
Found in a 1963 documentation, this circuit employs germanium transistors of the time. Transformer and...
In the figure we have a way of receiving ultrasonic signals of a single frequency using a PLL 567....
This traditional circuit generates a 200 Hz sinusoidal signal. The frequency depends on the...