Light intensity sensor circuit

It works based on sensing the intensity of light falling on light sensor. This is not only risky but also in wastage of power with the negligence of personnel or unusual circumstances in controlling these electrical appliances on and off. This allows them to be used in light sensing circuits.

To increase the sensitivity of light sensing , few modifications can be applied. As the intensity of the light increases, the output switches back and the relay is turned off.

Automatic dark detector senses darkness.

As the light level decreases and LDR meets the maximum threshold resistance, the circuit .

You can also make the LED turn ON when it is dark instead of when it is light. The LDR sensor has some special features as it changes its resistance with the change in the daylight intensity. It generates an output signal that is proportional to the intensity of light. A light sensor measures the radiant energy present in the wide range of frequencies in the light spectrum.

Some of the common frequencies are infrare visible and ultraviolet. These resistors are used as light sensors and the applications of LDR mainly include alarm locks, street lights, light intensity meters, burglar alarm circuits. In this project we are going to interface LDR with ATMEGAmicrocontroller, and with this we can measure LIGHT INTENSITY in the area. As shown in above figure, the resistance between the two contacts of sensor decreases with light intensity or the conductance between two contacts of sensor increases. The LED lights up when the intensity of the light reaching the LDR resistor is sufficient.

The 10K variable resistor is used to set the threshold at which the LED will turn on. If the LDR light is below the . They are most commonly found in industrial lighting , consumer electronics, and automotive systems, where they allow settings to be adjusted automatically in response to changing ambient light conditions. Circuit diagram description : 1. The best known devices of these types are the LDR ( light dependent resistor), the photodiode, the phototransistor, and the PIR (passive infrared) detector.

Arduino UNO Ris used in this project. Input voltage range: 85VAC ~ 2VAC external capacitor, recommended value 6. Ceramic capacitors C Ccan be used film capacitors or electrolytic capacitors. Light intensity sensor circuit.

That way the transistor stays off in the dark and starts to conducts when the photodiode is exposed to light.