Introduction

A Temperature Controlled Fan is an automatic system that turns ON or adjusts the speed of a fan based on the surrounding temperature. Such systems are widely used in electronic devices, server rooms, and home appliances to prevent overheating and improve energy efficiency.

This project demonstrates how temperature sensors can be used to control a fan automatically.

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Objective of the Project

The main objectives of this project are:

• To monitor ambient temperature.
• To automatically control a fan based on temperature.
• To reduce power consumption.
• To protect devices from overheating.

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Working Principle

The system works on the principle of temperature sensing and control.

Basic Operation

1. A temperature sensor (LM35) continuously senses temperature.
2. The sensor output voltage increases with temperature.
3. When the temperature exceeds a preset value, the control circuit activates.
4. The fan turns ON automatically.
5. When the temperature falls below the threshold, the fan turns OFF.

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Components Required

Basic Temperature Controlled Fan

• LM35 Temperature Sensor
• Comparator IC (LM358)
• Transistor (TIP122 / BC547)
• Relay / DC Fan
• Resistors
• Potentiometer (10kΩ)
• Diode (1N4007)
• Power Supply (12V)

Arduino-Based System

• Arduino Uno
• LM35 / DHT11 Sensor
• DC Fan
• Relay Module / Transistor
• Jumper wires

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Circuit Diagram

Basic Circuit

LM35 ---> Comparator ---> Transistor ---> Fan

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Arduino-Based Circuit

LM35 OUT ---- A0
Relay IN ---- D8
Fan -------- Relay Output
GND -------- Common Ground

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Arduino Code (Optional)

int tempPin = A0;
int relayPin = 8;

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

void loop() {
  int sensorValue = analogRead(tempPin);
  float voltage = sensorValue * (5.0 / 1023.0);
  float temperature = voltage * 100; // LM35 formula

  if (temperature > 30) {
    digitalWrite(relayPin, HIGH); // Fan ON
  } else {
    digitalWrite(relayPin, LOW);  // Fan OFF
  }

  delay(1000);
}

Code Explanation

• Arduino reads temperature from LM35.
• If temperature exceeds 30°C, the fan turns ON.
• Fan turns OFF when temperature drops.
• Threshold temperature can be adjusted.

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Advantages

• Automatic operation
• Energy efficient
• Prevents overheating
• Low maintenance

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Applications

• CPU cooling systems
• Electronic appliances
• Server rooms
• Smart homes
• Industrial machines

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Conclusion

The Temperature Controlled Fan project is a practical automation system that improves safety and efficiency. It demonstrates how sensors and control logic can be used to automate real-world devices. This project can be enhanced by adding speed control, LCD display, or IoT monitoring.

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