Description
Reviews
| 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 |
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.
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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