Gas leakage and smoke detection systems are important safety devices for homes, laboratories, kitchens, and workshops. In this project, we build a simple and affordable gas leakage alarm using an Arduino Arduino Uno, an MQ-2 gas sensor, and a buzzer.
The MQ-2 sensor can detect gases like LPG, methane, propane, hydrogen, and smoke. When the sensor detects gas above a certain threshold, the Arduino activates a buzzer to alert nearby people.
This project is beginner-friendly and a great introduction to sensors and safety systems.
Components Required
| Component | Quantity |
|---|---|
| Arduino Uno | 1 |
| MQ-2 Gas Sensor | 1 |
| Active Buzzer | 1 |
| Jumper Wires | Few |
| Breadboard (optional) | 1 |
How the MQ-2 Sensor Works
The MQ-2 sensor contains a sensitive material that changes resistance when exposed to combustible gases or smoke.
The sensor provides:
- Analog Output (AO) → Gas concentration value
- Digital Output (DO) → HIGH/LOW trigger output
In this project, we use the analog output for better sensitivity control.
Circuit Diagram
Circuit Connections
| MQ-2 Pin | Arduino Pin |
|---|---|
| VCC | 5V |
| GND | GND |
| AO | A0 |
| Buzzer Pin | Arduino Pin |
|---|---|
| Positive (+) | D8 |
| Negative (-) | GND |
Arduino Program
#define MQ2_PIN A0
#define BUZZER 13
/* Your code... */
int threshold = 400;
void setup() {
pinMode(BUZZER, OUTPUT);
digitalWrite(BUZZER, LOW);
Serial.begin(9600);
}
void loop() {
int gasValue = analogRead(MQ2_PIN);
Serial.print("Gas Value: ");
Serial.println(gasValue);
if (gasValue > threshold) {
digitalWrite(BUZZER, HIGH);
} else {
digitalWrite(BUZZER, LOW);
}
delay(200);
}