How to make Dark sensor without LDR | Dark Sensor Automatic Light Switch Circuit

It automatically switches ON lights control when the sunlight goes below the visible region of our eyes. it automatically switches OFF lights when the Sunlight falls on it, by using a sensor called Light Dependent Resistor(LDR) which senses the light just like our eyes.

Take the bc547 transistor and connect its base pin between the 33k resistor and LDR as shown in the circuit. Add a diode in series with the collector pin of the transistor and connect it to a positive supply.

An LDR's resistance levels. As the light level rises, the resistance value will decrease control system. LDR resistance values range from many megaohms in complete darkness to only a few hundred ohms in strong LED.

This sensor detects light falling on it and changes its resistance accordingly. This change in the resistance of LDR is detected by a circuit. Turn the LED ON When the light is not falling on LDR and turn the LED OFF when the light falling on LDR.

LDRs are tiny light-sensing devices also known as photoresistors or photodiodes. An LDR is a resistor whose resistance changes as the amount of light falling on it changes the system. The resistance of the LDR decreases with an increase in the light intensity system.