Attributes

Brand	-
Category	Robotics / STEM Teaching Tools / Sensors
Origin	-
Model Number	MQ-2-135-3-7-9
Detection Gases	LPG, Propane, Hydrogen, Smoke, Alcohol, CO
Operating Voltage	5V DC
Output Signal	Digital Switch Output (0 and 1) & Analog Voltage
Sensitivity Adjustment	Adjustable via Potentiometer
Indicator LED	Power and Alarm Status LEDs included
Pin Count	4 Pins (VCC, GND, DO, AO)
Material	PCB with Metal Mesh Sensor Housing
Compatibility	Arduino, Raspberry Pi, STM32, ESP8266
Preheat Time	Approximately 24-48 hours for stable readings

6 reviews

Anonymous

Mar 22, 2026

Rating: 4/5

Good value but needs warm-up

The build quality is solid for the price. Just remember that it needs a long preheat time before the readings stabilize. Once warmed up, it detects alcohol and gas very reliably.

Anonymous

Mar 21, 2026

Rating: 5/5

Perfect for my home safety project

This sensor module works exactly as described. I connected it to my Arduino Uno and was able to detect smoke from a blown-out candle within seconds. The analog output allows for fine-tuning sensitivity, which is great.

Anonymous

Mar 18, 2026

Rating: 5/5

Easy to interface

Plug and play with most microcontrollers. The pinout is standard, and the potentiometer makes calibration straightforward without needing complex code initially.

Anonymous

Mar 18, 2026

Rating: 4/5

Reliable detection range

We bought ten of these for our workshop. They consistently detect LPG leaks during our tests. The only downside is the power consumption is slightly higher than expected, but acceptable for stationary use.

Anonymous

Mar 17, 2026

Rating: 3/5

Works well but sensitive to humidity

The sensor detects gas effectively, but I noticed some fluctuation in readings when the room humidity changed drastically. Good for general detection, but maybe not for precise measurement without compensation.

Anonymous

Mar 01, 2026

Rating: 5/5

Great for university projects

Used this for a final year prototype on air quality monitoring. The digital output makes it easy to set a threshold alarm. Documentation online is plentiful which helped a lot.

5 FAQ

Q: Can I use this with a 3.3V Raspberry Pi?

A: Yes, but with caution. The VCC should ideally be 5V for the heater, but the signal pins might output 5V which can damage the Pi. We recommend using a logic level converter or a voltage divider on the output pins.

Q: Is the sensitivity fixed or can I adjust it?

A: The sensitivity is adjustable. There is a blue potentiometer on the board that allows you to set the threshold for the digital output pin (DO). Turning it changes the resistance and triggers the alarm at different gas concentrations.

Q: What is the voltage requirement for the analog output?

A: The module operates at 5V DC. The analog output voltage varies between 0V and 5V depending on the gas concentration detected. Please ensure your microcontroller's ADC can handle 5V logic.

Q: How long does it take for the sensor to be ready after powering on?

A: While the sensor may respond quickly, it requires a preheat time of approximately 24 to 48 hours for the internal heating element to stabilize and provide accurate, consistent readings.

Q: Does this sensor detect Carbon Dioxide (CO2)?

A: No, the MQ-2 module is designed primarily for combustible gases like LPG, propane, hydrogen, and smoke. It is not suitable for accurate Carbon Dioxide detection; you would need an MG-811 sensor for CO2.

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