Winsen MQ-2 Smoke & Flammable Gas Sensor Module

The MQ-2 requires two voltage inputs. The heater element needs a precise 5.0V ±0.1V AC or DC supply. The sensor's signal circuit (loop voltage, Vc) can operate with a wider range up to 24V DC, making it compatible with various microcontroller logic levels, including standard 5V Arduino boards.

Connect the module's VCC and GND to the Arduino's 5V and GND pins. For analog concentration reading, connect the AOUT pin to an Arduino analog input (e.g., A0). For a simple digital alarm, connect the DOUT pin to a digital input pin; the onboard potentiometer adjusts the detection threshold that triggers the digital signal.

The MQ-2 is sensitive to a broad range of flammable gases and vapors, including Liquefied Petroleum Gas (LPG), propane, hydrogen, methane, alcohol, and carbon monoxide (CO). It also responds well to smoke. Its highest sensitivity is typically to propane and LPG, making it a common choice for kitchen gas leak alarms.

Yes, the semiconductor sensing element requires a pre-heating period. Upon applying the 5V heater voltage, you should allow approximately 24-48 hours for the sensor to stabilize for the most accurate baseline readings. For initial testing, a shorter warm-up of several minutes is sufficient, but readings will drift during the initial burn-in period.

The MQ-2 is primarily designed for indoor use. Its bakelite and metal cap provide basic protection but it is not IP-rated for water or dust resistance. Performance can be affected by extreme temperatures, high humidity, and corrosive atmospheres. For outdoor or industrial settings, consider a housed transmitter version or installing the sensor in a protected, ventilated enclosure.