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.
The circuit shown is a low-power LED flashlight. The LEDs are white with a current of 20 mA, and...
This circuit for alternating current loads has a built-in timer. SCR2 is according to the motor...
The circuit shown in the figure generates a rectangular signal whose frequency depends on C1. For...