This product named Photoelectric detector(hereinafter called detector)detects the smoke by a couple of infrared diodes. The principle of detecting si granule in the smoke can reflect infrared light. Infrared diodes are placed in the special chamber. The chamber can shield external light, but don’t affect the smoke into it. While have no smoke, the diode can receive very weak infrared light. When the smoke entering the chamber, diode can receive more and more light, when the smoke attains the certain density, the detector can give out Mann signal. In order to reduce the interference and lower power consumnption,the emitting circuit adopts the pulse signal.The detector adopts the special structure design and ASIC, has the dustproof, mothproof and anti outside light interference feature etc.The detector is suitable for detect the smoke in house, shop, hotel, restaurant, officebuilding. school, bank, library, computer house and storehouse etc.