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Detailed Description:

The MQ-7 Gas Sensor Module is based on the MQ7 semiconductor sensor, designed to detect Carbon Monoxide (CO) in air. The sensor operates on a high-low heating cycle for accurate CO detection and can detect CO concentrations from 20 ppm to 2000 ppm.

It outputs both analog voltage for concentration measurement and digital output that goes HIGH when the gas exceeds a set threshold (adjustable via potentiometer). The MQ-7 is ideal for carbon monoxide alarms, indoor safety devices, and smart HVAC systems.

Key Features:

• Detects Carbon Monoxide (CO)

• Dual output: Analog (A0) and Digital (D0)

• Onboard potentiometer for threshold adjustment

• Long life and low cost

• Compatible with Arduino, ESP32, Raspberry Pi, STM32

• Suitable for home safety, IoT, HVAC, and air quality monitoring

Technical Specifications:

How to Use with Arduino:

Note: For accurate readings, MQ-7 requires cycling heater voltage – 5V for 60 seconds (high heating), then 1.4V for 90 seconds (low heating). Below is a basic code for demonstration purposes using analog readings (without cycling). For precise measurement, use a MOSFET or PWM-controlled heating system.

Arduino Sample Code (Simplified Analog Readout):

#define MQ7_A0 A0    // Analog pin for MQ-7 output

void setup() {
  Serial.begin(9600);
  pinMode(MQ7_A0, INPUT);
}

void loop() {
  int sensorValue = analogRead(MQ7_A0);
  float voltage = sensorValue * (5.0 / 1023.0);  // Convert to voltage
  Serial.print("Sensor Value: ");
  Serial.print(sensorValue);
  Serial.print(" | Voltage: ");
  Serial.println(voltage, 2);

  delay(1000);  // Read every 1 second
}

Note: For accurate ppm calibration, use gas calibration charts from the MQ-7 datasheet or apply a logarithmic conversion formula.

Applications:

• Carbon Monoxide (CO) leak detection

• Indoor air quality monitoring

• Smart HVAC safety systems

• Industrial and lab CO detectors

• IoT-based smart gas alarms

• Home, garage, or kitchen CO warning systems

• Fire and smoke warning prototypes

Package Includes:

• 1 x MQ-7 Carbon Monoxide Gas Sensor Module