In the laser infrared alarm, there is a photoresistor. What is it? How does a photoresistor work?
Photoresistor, also known as photoconductor, is made of special materials. Photoresistor is a special resistor made of semiconductor materials such as cadmium sulfide or cadmium selenide. Its surface is also coated with moisture-proof resin, which has photoconductive effect.
These materials have the following characteristics: Under normal conditions, they have a large resistance value. Under the irradiation of a certain frequency of light, the resistance value will rapidly decrease, so that the voltage at both ends will be reduced.
The working principle:
The working principle of photoresistor is based on the internal photoelectric effect, that is, the electrode lead is installed on both ends of the semiconductor photosensitive material and encapsulated in the shell with a transparent window to form the photosensitive resistance.
The photoresistor is a semiconductor photosensitive device. It has the advantages of high sensitivity, fast reaction speed, good consistency of spectral characteristics and resistance values. In addition, it can maintain high stability and reliability in the harsh environment of high temperature and humidity.
It can be widely used in camera, solar garden lamp, lawn lamp, cash detector, quartz clock, music cup, gift box, mini night light, acousto-optic switch, etc.