Gas Detector

This project shows you how to build a gas and smoke detector using an MQ‑2 sensor and an Arduino. The MQ‑2 can identify smoke, LPG, methane, and other gases, making it a useful tool for safety and electronics learning. Follow the steps to wire the components, upload the code, and test your own working detector.

This project shows you how to build a gas and smoke detector using an MQ‑2 sensor and an Arduino. The MQ‑2 can identify smoke, LPG, methane, and other gases, making it a useful tool for safety and electronics learning. Follow the steps to wire the components, upload the code, and test your own working detector.

1. Arduino Uno:
2. The main microcontroller board that reads the sensor and runs your code.
3. MQ-2 gas sensor module:
4. A module with pins typically labeled VCC, GND, DO, AO. It outputs both analog and digital signals.
5. Jumper wires:
6. To connect the sensor to the Arduino.
7. (Optional) LED + resistor (220 Ω):
8. To visually indicate gas detection.
9. (Optional) Buzzer:
10. For an audible alarm when gas is detected.

1. VCC: Power input (5 V)
2. GND: Ground
3. AO (Analog Out): Gives a variable voltage proportional to gas concentration
4. DO (Digital Out): Goes HIGH/LOW based on a threshold set by the onboard potentiometer

For this tutorial, we’ll mainly use AO with Arduino’s analog input

Connect everything on a breadboard or directly with jumper wires.

MQ-2 → Arduino:

1. VCC → 5V on Arduino
2. GND → GND on Arduino
3. AO → A0 on Arduino (analog input)

Optional LED (alert indicator):

1. LED anode (+) → digital pin 8 through a 220 Ω resistor
2. LED cathode (−) → GND

Optional buzzer:

1. Buzzer + → digital pin 9
2. Buzzer − → GND

int Input = A0;

int Buzzer = A1;

int GreenLED = A2;

int RedLED = A3;

int value;

int MAX = 600;

void setup() {

Serial.begin(9600);

pinMode(Input, INPUT);

pinMode(Buzzer, OUTPUT);

pinMode(GreenLED, OUTPUT);

pinMode(RedLED, OUTPUT);

}

void loop() {

value = analogRead(Input);

Serial.println(value);

if (value >= MAX) {

digitalWrite(GreenLED, LOW);

digitalWrite(RedLED, HIGH);

digitalWrite(Buzzer, HIGH);

delay(500);

} else {

digitalWrite(RedLED, LOW);

digitalWrite(Buzzer, LOW);

digitalWrite(GreenLED, HIGH);

}

}