How to Use MQ-2: Examples, Pinouts, and Specs

The MQ-2, manufactured by Zanefac (Part ID: MQ-2), is a versatile gas sensor designed to detect a variety of gases, including LPG, propane, methane, and smoke. It operates on the principle of resistive change when exposed to target gases, providing an analog output proportional to the gas concentration. This sensor is widely used in applications such as gas leak detection, air quality monitoring, and safety systems.

• Gas leak detection systems for homes and industries
• Air quality monitoring devices
• Smoke detection in fire alarm systems
• IoT-based environmental monitoring projects

The MQ-2 sensor is designed for ease of use and integration into various electronic systems. Below are its key technical details:

The MQ-2 sensor typically comes with four pins or terminals. Below is the pinout description:

The MQ-2 sensor is straightforward to use in a circuit. Follow the steps below to integrate it into your project:

1. Power Supply: Connect the VCC pin to a 5V DC power source and the GND pin to ground.
2. Analog Output: Connect the AOUT pin to an analog input pin of your microcontroller (e.g., Arduino UNO) to read gas concentration levels.
3. Digital Output: Optionally, connect the DOUT pin to a digital input pin of your microcontroller. Use the onboard potentiometer to set the gas concentration threshold for triggering the digital output.

• Preheating: Allow the sensor to preheat for at least 24 hours before taking accurate readings. This ensures the internal heater stabilizes.
• Calibration: Calibrate the sensor in a clean air environment to establish a baseline reading.
• Placement: Place the sensor in a well-ventilated area for accurate gas detection.
• Load Resistor: Use a load resistor (RL) of 10 kΩ for typical applications. Adjust as needed for specific use cases.

Below is an example code snippet to interface the MQ-2 sensor with an Arduino UNO and read the analog output:

// MQ-2 Gas Sensor Example Code
// Manufacturer: Zanefac
// Part ID: MQ-2
// This code reads the analog output of the MQ-2 sensor and prints the value to the Serial Monitor.

const int analogPin = A0; // Connect AOUT pin of MQ-2 to Arduino analog pin A0
int sensorValue = 0;      // Variable to store the sensor reading

void setup() {
  Serial.begin(9600); // Initialize serial communication at 9600 baud
  Serial.println("MQ-2 Gas Sensor Test");
}

void loop() {
  sensorValue = analogRead(analogPin); // Read the analog value from the sensor
  Serial.print("Gas Concentration (Analog Value): ");
  Serial.println(sensorValue); // Print the sensor value to the Serial Monitor
  delay(1000); // Wait for 1 second before the next reading
}

• Avoid exposing the sensor to high concentrations of corrosive gases, as this may damage the sensing element.
• Use a stable 5V power supply to ensure consistent readings.
• Regularly clean the sensor to remove dust or debris that may affect performance.

1. No Output or Incorrect Readings:

   • Ensure the sensor is properly connected to the power supply and ground.
   • Verify that the sensor has been preheated for at least 24 hours.
   • Check the load resistor value and adjust if necessary.

2. Fluctuating Readings:

   • Ensure the sensor is placed in a stable environment without sudden changes in temperature or humidity.
   • Use a decoupling capacitor (e.g., 0.1 µF) across the power supply pins to reduce noise.

3. Digital Output Not Triggering:

   • Adjust the onboard potentiometer to set the desired gas concentration threshold.
   • Verify the digital pin connection to the microcontroller.

Q1: Can the MQ-2 detect multiple gases simultaneously?
A1: Yes, the MQ-2 can detect multiple gases such as LPG, propane, methane, and smoke. However, it does not differentiate between them; it provides a combined analog output based on the total gas concentration.

Q2: How do I calibrate the MQ-2 sensor?
A2: To calibrate, expose the sensor to clean air and record the baseline analog output. Use this value as a reference for detecting gas concentrations.

Q3: Can the MQ-2 be used outdoors?
A3: The MQ-2 is not designed for outdoor use as it may be affected by extreme temperatures, humidity, and environmental contaminants. Use it in controlled indoor environments for best results.

Q4: What is the lifespan of the MQ-2 sensor?
A4: The typical lifespan of the MQ-2 sensor is around 2–3 years under normal operating conditions. Regular maintenance can help extend its life.

By following this documentation, users can effectively integrate and utilize the MQ-2 gas sensor in their projects.