What is a Smoke Sensor MQ-2? A Complete Guide to Digital & Analog Connectivity, Pin Configuration, and Interfacing with Arduino Uno

A Comprehensive Guide to the Smoke Sensor MQ-2: Detection, Interfacing, and Applications

Introduction

The MQ-2 smoke sensor is a versatile and reliable module designed to detect a variety of gases, including methane, LPG, carbon monoxide, alcohol, propane, and hydrogen. Widely utilized in safety, security, and environmental monitoring projects, the MQ-2 is ideal for building smoke alarms, gas leak detectors, and air quality monitoring systems. Whether you’re a student, hobbyist, or professional, the MQ-2 sensor offers affordability, accuracy, and ease of use for your innovative projects.

What is the Smoke Sensor MQ-2?

The MQ-2 smoke sensor is a gas detection module that employs a semiconductor-based sensing element to identify the presence of harmful or flammable gases. It features:

Dual Output Modes:

Analog Output (AO):

Provides a continuous voltage signal proportional to gas concentration for precise monitoring.

Digital Output (DO):

Delivers a simple HIGH or LOW signal when the gas concentration exceeds a predefined threshold, perfect for triggering alarms

Wide Range of Detection:

Capable of detecting gas concentrations from 300 ppm to 10,000 ppm.

Technical Specifications

Operating Voltage: 5V DC
Current Consumption: ≤150mA
Response Time: ≤10 seconds
Preheating Time: ~20 seconds
Detection Range: 300 ppm to 10,000 ppm

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Pin Configuration

The MQ-2 sensor module comes with four essential pins:

VCC: Connects to the 5V power supply.
GND: Ground connection.
DO (Digital Output): Outputs HIGH/LOW signals based on gas concentration.
AO (Analog Output): Provides variable voltage proportional to gas concentration.

How Does the MQ-2 Smoke Sensor Work?

The MQ-2 operates via a gas-sensitive resistor that changes resistance when exposed to gas molecules. This resistance variation is converted into an electrical signal, enabling accurate gas concentration monitoring

Interfacing the MQ-2 Sensor with Arduino Uno

Required Components:

MQ-2 smoke sensor module
Arduino Uno board
Jumper wires
Breadboard
LED (optional for visual indication)

Wiring Instructions:

Connect VCC to the Arduino’s 5V pin.
Connect GND to the Arduino’s GND pin.
Connect AO to an analog input pin (e.g., A0) for analog readings.
Connect DO to a digital pin (e.g., D2) for digital readings.

Arduino code for smoke detection system

    
     int analogPin = A0; // Analog pin connected to AO
int digitalPin = 2; // Digital pin connected to DO
int ledPin = 13;    // LED connected to digital pin 13

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

void loop() {
  int analogValue = analogRead(analogPin);
  int digitalValue = digitalRead(digitalPin);

  Serial.print("Analog Value: ");
  Serial.println(analogValue);
  Serial.print("Digital Value: ");
  Serial.println(digitalValue);

  if (digitalValue == HIGH) {
    digitalWrite(ledPin, HIGH); // Turn on LED if gas is detected
  } else {
    digitalWrite(ledPin, LOW);  // Turn off LED if no gas is detected
  }

  delay(1000);
}

This code reads the analog and digital values from the MQ-2 sensor. It lights up the LED if the gas concentration exceeds the threshold while displaying values on the Serial Monitor.

Applications of the MQ-2 Sensor

The MQ-2 sensor is highly versatile and finds applications in:

Smoke Alarm Detectors:

Early warning systems for fire hazards. Gas Leak Detectors: Monitoring LPG, methane,. other flammable gases.

Home Security Systems:

Detecting hazardous gas leaks.

Environmental Monitoring:

Measuring air quality.

Science and Engineering Projects:

Ideal for school and final-year projects.

Buying MQ-2 Sensors from QKZee Technologies For authentic MQ-2 smoke sensors and other electronic components, visit QKZee Technologies at Hall Road, Lahore. Known for their reliable engineering services and high-quality products, QKZee Technologies is your one-stop shop for electronic components and project supplies in Pakistan.

Why Choose QKZee Technologies?

Best Prices in Lahore: Affordable and genuine components for your projects.
Wide Range of Products: From sensors to modules, catering to beginners and professionals alike.
Exceptional Customer Service: Expert guidance for engineering and DIY projects.
Convenient Location: Located at Hall Road, Lahore—a hub for electronics enthusiasts.

How to Connect with QKZee Technologies:

Visit their store at Hall Road, Lahore.
Browse their online catalog for detailed product listings and specifications.
Contact their support team for assistance.

What gases can the MQ-2 sensor detect?

the MQ-2 sensor can detect methane, LPG, carbon monoxide, alcohol, propane, hydrogen, and smoke.

What is the response time of the MQ-2 sensor?

The MQ-2 sensor has a response time of less than 10 seconds, making it highly responsive to gas concentration changes.

Can I use the MQ-2 sensor with a 3.3V microcontroller?

The MQ-2 sensor requires a 5V power supply for optimal performance. If using a 3.3V microcontroller, consider using a level shifter or regulator.

How do I calibrate the MQ-2 sensor?

Calibration involves exposing the sensor to a known gas concentration and adjusting the potentiometer on the module to set the desired threshold for the digital output.

Is the MQ-2 sensor suitable for outdoor use?

The MQ-2 sensor is not weatherproof and should be used in controlled indoor environments to avoid inaccurate readings due to humidity or temperature fluctuations.