Arduino Automatic Street Light Project (With Circuit & Code)

Project Name

Automatic Street Light Using Arduino and LDR

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📌 Introduction

In this Arduino project, we will make an Automatic Street Light System using an Arduino UNO and an LDR (Light Dependent Resistor).
The light turns ON automatically at night and OFF during daytime.
This project is widely used in smart cities, energy saving systems, and home automation.

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🧠 Working Principle

• LDR senses sunlight

• When light is high (day) → Resistance of LDR is low → LED OFF

• When light is low (night) → Resistance of LDR is high → LED ON

• Arduino reads LDR value and controls the LED automatically

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🧰 Components Required

Component	Quantity
Arduino UNO	1
LDR (Light Sensor)	1
LED	1
220Ω Resistor	1
10kΩ Resistor	1
Breadboard	1
Jumper Wires	As required
USB Cable	1

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🔌 Circuit Connections

📍 LDR Connections

LDR Pin	Connection
One leg	5V
Other leg	A0 + 10kΩ to GND

📍 LED Connections

LED Pin	Connection
Anode (+)	Digital Pin 9
Cathode (–)	220Ω Resistor → GND

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🧾 Arduino Code

int ldrPin = A0;
int ledPin = 9;
int ldrValue = 0;

void setup() {
  pinMode(ledPin, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  ldrValue = analogRead(ldrPin);
  Serial.println(ldrValue);

  if (ldrValue < 400) {   // Night condition
    digitalWrite(ledPin, HIGH);
  } else {               // Day condition
    digitalWrite(ledPin, LOW);
  }
  delay(500);
}

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⚙️ How to Upload Code

1. Open Arduino IDE

2. Select Board: Arduino UNO

3. Select correct COM Port

4. Paste the code

5. Click Upload

🎯 Advantages

✔ Saves electricity
✔ Fully automatic
✔ Low cost
✔ Easy to build
✔ Beginner friendly

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📌 Conclusion

This Arduino Automatic Street Light Project is simple, useful, and perfect for students and beginners. It helps understand sensors, analog input, and automatic control systems.

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