This sensor uses a non-modulated laser receiver. Please use it in a place where there is no light in the room. Sunlight or other lamps may interfere. It is recommended to use it in a dark environment. 5V laser receiver sensor module relay switch for Arduino, it is a non-modulated laser receiver module, has two layers circuit board, has given room for a mounting hole. It's sensitive to ambient light, please keep the sensor in the dark environment. Or it can be tripped by ambient light, suggest shielding the sensor by a black tube if it is necessary for bright areas. Working voltage: 5V, module size: 1.52x2.22cm/0.6"x0.9". The sensor is bent for easier shipping, user can adjust it easily. Warm tips: Users need to have relevant electronic knowledge to test this module, due to some improper use will damage the module, such as input voltage is too high, the power supply is unstable, polarity reversed. All of these sensor modules pass the quality inspection one by one before shipping. In case you received the defective module, please contact with Electrobot service team firstly, all customers emails will be replied in 24 hours as technology supports.