Smoke detector is a device incorporated on fire alarm system; it is usually installed on buildings to alarm the occupants when there is a fire (when there’s smoke, there’s fire). This provides the crucial early warning to escape injury or death in fire. This project uses optical method design; the sensing part is the photo chamber that is composed of infrared light source and a photoelectric receiver (photodiode).
The design of this project is not so complicated because of the specialized IC (Integrated Circuit) intended for smoke detection. The RE46C190 smoke detector IC provides all the required features for a photoelectric smoke detector type of electronic project with minimal external component needed. During standby mode, the RE46C190 IC is programed to check the battery condition every 86 seconds and the chamber integrity every 43 seconds. Interconnection between multiple detectors (through I/O PIN-12) is also possible; this will activate all the connected detectors when one of the units is triggered.
For more detail: Photoelectric Smoke Detector