A simple and interesting project of a light activated LED circuit, which will light up an LED when receives light. The circuit is very easy to build and using only six components. The photoresistor is performing the light sensing task. The transistor 2N2222 is working as a switch in this circuit. When any type of
light like sunlight, bulb or lamp light will fall on the surface of photoresistor it will switch on the transistor and the LED will lightup. The 50K variable resistor (VR) is used to adjust the amount of light on which you want to lightup the LED. The 1K resistor is used to protect the photoresistor from direct connecting to the supply when the variable resistor is on zero and 330 ohms resistor is used for providing the required current to the LED. The circuit can be operated with four 1.5V batteries of any size.