Light Sensor Circuit

Abstract

The presence of light increases current in the photo diode or phototransistor. LM317 supplied lower voltage DC power in the circuit. Capacitors are connected in parallel with the DC output in order to filter out any high frequency AC signal coming from the noise. NE555P Timer produced accurate oscillation. BPV11 is used as a photodiode. LM311 is the comparator and the light on/off is converted to low/ high of the comparator output.

Keywords: Photodiode, phototransistor, comparator, green LED, oscillation, signal, sensor, circuit, power supply