LC-tank circuit portion. Varactor (or “varicap”) diodes are used primarily in radio-frequency (RF) circuits to provide a capacitance that can be varied by changing the applied voltage.

Designed to control the frequency of crystal oscillator circuits, the 3022 series of high-ratio, hyperabrupt varactor tuning diodes is designed to deliver a dc bias control voltage from -0.3V to -4V.

In contrastm the transmitter schematic we present here eliminates some of those problems, using varactor diode for tuning and modulation, givind great sensitivity without an audio amplifier. ...

But d is the length of the depletion region which depends on V – the reverse-bias voltage. As V increases, d increases and C decreases. There’s your voltage controlled capacitor. Any diode can be used ...

This is achieved by the modulation module of the LASER COMPONENTS-made controller L5830. The generation of an additional external frequency is not necessary. Perhaps one reason that the derivative ...