LDR sensor is a special resistor made of semiconductor materials such as sulfide or selenide barrier. It is also coated with moisture-proof resin and has photoconductive effect.
Detection methods of LDR sensors
1. Cover the light-transmitting window of the LDR photoresistor with a black paper sheet. At this time, the pointer of the multimeter is basically fixed, and the resistance value is close to infinity. The larger the value, the better the performance of the LDR sensor. If this value is very small or close to zero, it means that the LDR sensor has been burned out and damaged, so it can not be used again.
2. When a light source is aligned with the transparent window of the LDR sensor, the pointer of the multimeter should oscillate considerably and the resistance value will decrease obviously. The less this value, the better the performance of the LDR photocell. If this value is large or even infinite, it indicates that the open circuit inside the LDR sensor is damaged abd it can not be used again.
3. Directing the translucent window of the LDR sensor to the incident light and shaking the upper part of the light-shielding window of the LDR sensor with small black paper makes it receive light intermittently. At this time, the pointer of the multimeter should swing left and right with the shaking of the black paper. If the multimeter pointer always stops at a certain position and does not oscillate with the paper, it indicates that the photosensitive material of the LDR sensor has been damaged.