DC-9102E Conventional Photoelectric Smoke Detector is a new-generation product. With built-in microprocessor, the detector is highly fixed with reliable fire judging program, which make it stable and reliable performance. When the detector checks fire signal, it will send fire information to the control panel or addressable zone monitor unit by means of current changing. The detector keeps turning on the LED to indicate alarm state until it is reset. The detector is developed from sensing chamber by scattering theory. It has the ability to resist dust contamination and environmental light. The detector utilizes drift compensation algorithm: When the environment is changing, such as dust accumulation, humidity and temperature changing, the detector can figure out these drift variation to make up for sensitivity, thus the amount of smoke needed to generate an alarm remains constant, irrespective of environmental conditions. The principle diagram is shown as Fig. 1.