Experiments with a varicap

The capacitance versus voltage relationship (the C-V characteristic) of a varicap is determined, and the device is used for tuning an LC circuit and for building a voltage-controlled oscillator. With a data-acquisition system, the C-V characteristic can be demonstrated in a short time. The necessary equipment includes a function generator, an oscilloscope, a 9 V battery, capacitors, resistors, coils, and a multimeter. The varicap provides good opportunities for experimentation with electrical circuits. The experiments may be offered as student activities.