Description

The MQ-7 Carbon Monoxide Gas Sensor Module is an essential safety component designed for indoor air monitoring, combustion exhaust tracking, and industrial safety alarms. Because carbon monoxide is an odorless, colorless, and highly hazardous gas, accurate detection at low concentrations is vital for human safety.

The sensor works on the principle of electrical conductivity variation: in clean air, the SnO2 sensing layer exhibits low conductivity. When carbon monoxide gas is present, the sensor’s conductivity increases in direct proportion to the gas concentration. The onboard conditioning circuit converts this conductivity change into a readable analog voltage signal (AO). Additionally, an onboard LM393 comparator IC compares the analog voltage against a user-defined threshold (set via the blue trimmer potentiometer) to toggle a logic Digital Output (DO) signal for direct relay or microcontroller interrupt activation.

Technical Specifications

Module Pinout & Control Hardware

                  +----------------------------------+
                  |  [VCC]  [GND]  [DOUT]  [AOUT]    |
                  |   (o)    (o)    (o)     (o)      |
                  |                                  |
                  |    [ LM393 Comparator IC ]       |
                  |    [ Trimmer Potentiometer ]     |
                  |                                  |
                  |      ( MQ-7 Sensor Cap )         |
                  +----------------------------------+

Basic Arduino Interfacing Code

// MQ-7 Carbon Monoxide Sensor Arduino Connection Test
#define MQ7_ANALOG_PIN A0
#define MQ7_DIGITAL_PIN 2
#define ALARM_LED 13

void setup() {
  pinMode(MQ7_DIGITAL_PIN, INPUT);
  pinMode(ALARM_LED, OUTPUT);
  Serial.begin(9600);
  
  Serial.println("MQ-7 CO Sensor Initializing... (Allow warm-up time)");
}

void loop() {
  int rawAnalogValue = analogRead(MQ7_ANALOG_PIN);
  int digitalStatus = digitalRead(MQ7_DIGITAL_PIN);

  Serial.print("CO Analog Value: ");
  Serial.print(rawAnalogValue);
  
  // Check if threshold is breached (LM393 DOUT goes LOW)
  if (digitalStatus == LOW) {
    digitalWrite(ALARM_LED, HIGH);
    Serial.println(" | WARNING: CO Gas Detected above threshold!");
  } else {
    digitalWrite(ALARM_LED, LOW);
    Serial.println(" | Air Quality Normal");
  }

  delay(500);
}

Key Features & Highlights

• High Sensitivity to Carbon Monoxide: Specifically tuned to measure low CO levels (10 to 1000 ppm) before reaching dangerous thresholds.

• Dual Output Architecture: Features both Analog Output (for precise PPM calculation) and Digital Output (for threshold-triggered alarms).

• Onboard Potentiometer: Allows easy manual adjustment of the digital alarm threshold limit without modifying software code.

• Rapid Response Time: SnO2 heating element ensures quick recovery and fast reaction to changing gas levels in ambient air.

• Universal Microcontroller Compatibility: Connects directly to Arduino, ESP32, ESP8266, STM32, and Raspberry Pi GPIOs.

Common Applications

• Residential carbon monoxide safety alarms and kitchen gas leak monitoring.

• Industrial boiler rooms, parking garages, and vehicle exhaust monitoring systems.

• Environmental air quality tracking nodes and smart city IoT stations.

• Portable gas detection wands and safety warning hardware.

What’s Included in the Box

• 1 × MQ-7 CO Carbon Monoxide Coal Gas Sensor Module

Why Buy From Aryabot?

• 100% Bench Inspected: Verified for heater filament resistance, LM393 comparator switching, and analog output response.

• Reliable Sensor Quality: Sourced with genuine SnO2 semiconductor element caps for accurate sensing.

• GST Invoice Provided: Tax-compliant B2B invoices generated for academic institutions, corporate R&D units, and maker labs.

• Pan-India Express Dispatch: Anti-static protective packaging shipped directly from our Noida fulfillment facility.