Attributes

Brand	-
Category	Robotics / STEM Teaching Tools / Sensors
Origin	-
Model Number	MQ-2-135-3-7-9
Detection Gases	Smoke, LPG, Alcohol, Hydrogen, CO
Operating Voltage	5V DC
Output Signal	Analog and Digital (TTL)
Preheat Time	24-48 Hours
Sensitivity Adjustment	Potentiometer Included
Interface Type	3-Pin Header (VCC, GND, OUT)
Dimensions	32mm x 20mm x 15mm
Compatibility	Arduino, Raspberry Pi, ESP32
Mounting Style	Through-hole with Standoffs

6 reviews

Anonymous

Mar 29, 2026

Rating: 5/5

Reliable gas detection

Integrated this into my smart home system to monitor the garage for fuel leaks. It picks up hydrogen and combustible gases quickly. The digital output pin is a nice feature for simple alarm triggers.

Anonymous

Mar 18, 2026

Rating: 5/5

Great addition to my greenhouse monitor

Using this to monitor air quality and potential fermentation gases in my composting area. It responds well to changes in air composition. The build quality feels sturdy enough for long-term use.

Anonymous

Mar 15, 2026

Rating: 4/5

Good sensitivity, needs patience

The sensor is very sensitive to alcohol and smoke as advertised. Just remember to let it warm up for at least 24 hours before calibrating, or your readings will be all over the place. Once calibrated, it's solid.

Anonymous

Mar 14, 2026

Rating: 4/5

Works well but gets hot

Functionality is top-notch for the cost. Be aware that the heating element inside gets quite hot during operation, which is normal for this type of sensor, but ensure your enclosure has ventilation.

Anonymous

Mar 06, 2026

Rating: 5/5

Excellent for learning embedded systems

Bought this for a university project on air quality monitoring. The documentation provided by the seller was helpful, and the potentiometer makes threshold adjustment very easy. Highly recommended for students.

Anonymous

Mar 04, 2026

Rating: 5/5

Perfect for home safety projects

This sensor module works flawlessly with my Arduino setup. The analog output is stable after the initial preheat time, and detecting smoke from a simple test was immediate. Great value for the price.

5 FAQ

Q: Does this module require an external library to work with Arduino?

A: No external library is strictly required. You can read the analog value using the standard analogRead() function. However, many users find community libraries helpful for calibration and unit conversion.

Q: Can this detect natural gas specifically?

A: Yes, the MQ-2 sensor is sensitive to methane and other combustible gases found in natural gas, though it is not specific to one gas type and reacts to a range of combustible vapors.

Q: Is the digital output adjustable?

A: Yes, there is a blue potentiometer on the board that allows you to adjust the sensitivity threshold for the digital output pin (DO). Turning it changes the point at which the LED lights up and the signal goes low.

Q: What is the exact preheat time needed before accurate readings?

A: For stable and accurate baseline readings, we recommend a preheat time of 24 to 48 hours. Shorter periods may result in fluctuating values as the sensor element stabilizes.

Q: What is the power consumption of this module?

A: The module typically consumes around 150mA to 200mA at 5V due to the internal heating element required for the sensor to operate correctly. Ensure your power supply can handle this load.

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