Found in an old American documentation this FM modulator makes use of a varactor diode. The circuit can be easily implemented given the small number of components used.
This interesting circuit from Radio Elecronics from October 1965 shows a flip-flop or bistable with...
The basic idea of the circuit shown in the figure is to increase the brightness of an ordinary...
Found in an American documentation, this regulator supplies a current according to the integrated...