MQ-9 CO and Methane Gas Sensor Module
The MQ-9 Gas Sensor Module is a versatile and highly sensitive device designed for the detection of carbon monoxide (CO), methane (CH₄), and liquefied petroleum gas (LPG). It utilizes the MQ-9 semiconductor gas sensor, which changes its resistance when exposed to target gases, enabling both qualitative and quantitative measurements.
The module offers two types of outputs: an Analog Output (AO) that delivers a continuous voltage proportional to the gas concentration, and a Digital Output (DO) that switches when the gas level exceeds a preset threshold, adjustable via the onboard potentiometer. This dual-output design makes it ideal for both data logging and real-time safety triggers.
Powered by a standard 5 V DC supply, the MQ-9 integrates seamlessly with popular microcontrollers like Arduino, ESP32, and Raspberry Pi. It also features an onboard LM393 comparator for reliable digital signal processing, as well as LED indicators for power and gas detection status.
Key Features
Detects CO, methane, and LPG gases
Analog (AO) and digital (DO) outputs
Adjustable sensitivity via potentiometer
Operates on 5 V DC, microcontroller-friendly
LED indicators for power and detection status
Compact and easy-to-use 4-pin interface
Product Specifications
| Specification | Details |
|---|---|
| Operating Voltage | 5 V DC |
| Sensor Type | MQ-9 semiconductor gas sensor |
| Comparator | LM393 |
| Detection Range | CO: 10–1000 ppm, CH₄ & LPG: 100–10,000 ppm |
| Heater Resistance | ~31 Ω ± 3 Ω (room temperature) |
| Heating Power | ≤ 900 mW |
| Analog Output | Voltage proportional to gas concentration |
| Digital Output | HIGH when threshold exceeded |
| Sensitivity Control | Adjustable via potentiometer |
| Current Consumption | ~150 mA ‘ |
| Module Size | Compact, breadboard-friendly |
Pin Configuration
| Pin | Label | Description |
|---|---|---|
| 1 | AO | Analog output (gas concentration) |
| 2 | DO | Digital output (threshold trigger) |
| 3 | GND | Ground |
| 4 | VCC | 5 V DC Power Supply |
Applications
Carbon monoxide detection in homes and offices
Methane and LPG leak detection systems
Industrial safety monitoring
Smart home automation and IoT devices
Portable gas detectors
Educational electronics projects
