13-02-2018, 11:42 AM
Circuit IR works on the principle of sensing. Infrared or only IR sensors are devices that work with infrared light source and a photo detector such as photo diode or a photo transistor that acts as a transmitter and receiver, respectively. In this project, we have used IR LED as a photo diode in the form of IR transmitter and IR receiver. Two sets of IR sensor with an IR LED and Photo Diode are placed at two ends of the entrance to a room. Output from each sensor is fed to the microcontroller. In normal operation, the IR light from the LED does not fall on the photo diode because it is a reflective type IR sensor. Output from the sensor will be less signal in this case. In case of any blockage (due to any person crossing the path), photo diodes will start receiving IR lights and start operations. As a result, the output from the sensor will be high signal.