What is a varactor and how to detect it?

Variable capacitance diode is made of special materials. When the voltage is added to PN junction, the power supply capacity will change.

The voltage and current characteristics and internal structure of varactor are the same as those of ordinary diode.

Under reverse bias voltage, varactor shows larger junction capacitance. The capacitance of this junction capacitance C can vary with the magnitude of the reverse bias voltage. The higher the reverse voltage, the smaller the capacitance; the smaller the reverse voltage, the greater the capacitance.

The capacity of the varactor diode junction capacitance Cj varies with the applied reverse bias voltage.

If a varactor with a certain DC reverse voltage is applied to the loop of the oscillator, the junction capacitance of the varactor can be achieved.

The oscillation frequency of the oscillator can be controlled by adjusting the voltage of the resonant loop capacitor.

Detect a varactor

Because the positive resistance of the varactor diode is larger, the multimeter is placed in the RX 10kΩ block, the red pen is connected to the positive pole, the black pen is connected to the negative pole, and the resistance value between the two pins should be infinite. If it is found that the pointer of the multimeter has a slight swing or a resistance value to zero on the measurement, it means that the varactor diode has leakage fault or has been damaged.

Reverse the form, that is, the red pen is connected to the negative pole and the black pen is connected to the positive pole. The measured resistance should be around hundreds of thousands of euros.

For the vanishing capacity of the varactor or the open-circuit fault inside, the multimeter can not be use to detecte, and the replacement method is applied to judge.

If you want to know more, our website has product specifications for the varactors, you can go to ALLICDATA ELECTRONICS LIMITED to get more information.