MQ‑2 (Smoke-Gas) Sensor Module
The MQ‑2 Smoke/Gas Sensor Module delivers reliable detection of flammable gases and smoke, making it a popular choice for safety, automation, and environmental monitoring projects. It combines a sensitive MQ‑2 semiconductor gas sensor—primarily responsive to LPG, propane, hydrogen, and smoke—with an onboard LM393 comparator and potentiometer to enable both analog and digital output capabilities.
When volatile gases or smoke reach the sensor, the conductivity of its SnO₂ sensing layer increases, resulting in a readable voltage change. The Analog Output (AO) provides a continuous voltage proportional to gas concentration, perfect for quantitative monitoring. The Digital Output (DO) switches state when concentration exceeds the threshold you set via the potentiometer—ideal for triggering alarms or safety controls.
With compatibility for 5V operation, this module integrates smoothly with microcontrollers like Arduino, ESP32, or Raspberry Pi. Built-in LEDs make calibration intuitive: the power LED confirms module status, and the signal LED lights up when the gas level crosses the threshold.
This component excels in applications like home gas leak detection, industrial safety systems, air quality monitoring, and smoke alarms. Its simple interface and reliable performance render it a go-to tool for both beginners and advanced developers.
Key Features
Detects flammable gases: LPG, propane, hydrogen, methane, and smoke
Dual outputs: analog for concentration reading, digital for threshold alerts
Adjustable sensitivity via onboard potentiometer
Built-in power and indicator LEDs
Compatible with 5V systems
Compact design suitable for quick prototyping
Product Specifications
| Specification | Details |
|---|---|
| Operating Voltage | 5 V DC |
| Sensor Type | MQ‑2 semiconductor gas sensor |
| Comparator | LM393 |
| Analog Output (AO) | Voltage proportional to gas concentration |
| Digital Output (DO) | Switches based on adjustable threshold |
| Heater Resistance | ~33 Ω ±5% |
| Heating Power | <800 mW |
| Detectable Gas Range | Smoke, LPG, Alcohol, Propane, Hydrogen etc. |
| Sensitivity Adjustment | Yes (potentiometer) – |
| LEDs | Power + Signal indicators |
| Typical Consumption | ~150 mA |
| Module Size | ~32 mm × 20 mm (approx.) |
Pin Configuration
| Pin | Label | Description |
|---|---|---|
| 1 | AO | Analog output – proportional to gas concentration |
| 2 | DO | Digital output – triggers when threshold exceeded |
| 3 | GND | Ground |
| 4 | VCC | Power supply (5 V) |
Applications
Home and industrial gas leak detection systems
Smoke and fire alarms
Air quality monitoring
Safety interlocks for heating systems
Hobbyist environmental sensing projects
