With the "information age" arrive, As the means to take in information the sensor technology has been prominence progress, there are more and more extensive areas of its application, its requirements and needs become more and more high. Sensor technology has become an important landmark to measure a country's level of development of science and technology . Therefore, to understand and master various types of sensors’ basic structure, working principle and characteristics are very important. Now on the market smoke alarm sensors mainly include semiconductor-type, photoelectric, ion type and so on.
This article introduces the use of common time-base integrated circuit 555 to achieve design, 555’s features include low current, low power, to adapt wide supply voltage range. This circuit comprehensive the advantages and disadvantages choose photoelectric sensors. Using the alarm buzzer alarm circuit, when the smoke concentration reached a certain level it can produce a voice and visual alarm.
