Automatic Street Light Circuit

Introduction:

                        Welcome to the "Automatic Street Light Working Model" project. This circuit relies on the Light Dependent Resistor (LDR) for its operation. The LDR, which stands for "Light Dependent Resistor," varies its resistance based on the intensity of light falling on it. When exposed to light, the LDR's resistance is low, while in darkness, the resistance becomes high. This fundamental principle of the LDR forms the basis of this project. Now, let's delve into the steps on "How to Make this Circuit."

Connection:

                      Begin by taking the Dot Board and carefully placing and soldering the components according to the circuit diagram. Position the 100K Resistor on the left side of the Transistor (Q1) and solder it. Connect the LDR in series with the 100K Resistor and solder it. Place the 1K Resistor on the Collector of Q1 Transistor and solder it. Connect the 2nd pin of the LDR and the Emitter pin of Q2 Transistor to the ground of the power supply. Link the Emitter of the 1st Transistor to the Base of the 2nd Transistor and solder it. Connect the Collector pin of Q2 Transistor to the 470Ω Resistor in series with the negative terminal of the White Color LED, and connect the positive terminal of the LED to the positive of the power supply. Connect the 1st pins of the 100KΩ and 1KΩ Resistors to the positive of the power supply. Thus, the Automatic Street Light Circuit is completed.

Circuit Diagram:

Working:

                This circuit operates based on the Light Dependent Resistor (LDR). When light falls on the LDR, its resistance decreases, and when in darkness, the resistance increases. When the surroundings become dark, a voltage drop occurs between the LDR and the base of the 1st Transistor. This voltage drop activates the 2nd Transistor through its base, turning on the LED, which starts flashing. When light falls on the LDR again, the LED turns off.

 Note:

        You can use any other DC LED lights by adjusting the input voltage, or alternatively, use a relay to operate AC LED lights.

Part List:

1)  BC 548 Transistor =2

2)  100KΩ ¼ Watt Resistor =1

3)  1KΩ ¼ Watt Resistor =1

4)  470Ω ¼ Watt Resistor =1

5)  5mm LDR =1

6)  White Color LED =1

7)  DOT Board =1

8)  Power Supply

9)  Some Wires

Click Here to See the "Automatic Street Light Controller Circuit". In this Circuit, You can Use any 220VAC Light.

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By,

G. Guruvel Sarveshwar

EEE Dept