Description
Reviews
| Brand | - |
| Category | Robotics / STEM Teaching Tools / Sensors |
| Origin | - |
| Model Number | MQ-135 |
| Detection Gases | Ammonia, NOx, Alcohol, Benzene, Smoke, CO2 |
| Operating Voltage | 5V DC |
| Output Signal | Analog and Digital (TTL) |
| Preheat Time | 24-48 Hours |
| Load Resistance | 20kΩ (Adjustable) |
| Heater Resistance | 33Ω ± 5% |
| Heater Current | < 150mA |
| Interface Type | 3-Pin Header (VCC, GND, OUT) |
| Compatible Boards | Arduino, Raspberry Pi, ESP32, STM32 |
Anonymous
Mar 29, 2026
Rating: 4/5
Sensitive and responsive
It picks up even slight changes in air quality. I tested it with a lighter and it reacted instantly. Deducting one star only because the pins were slightly bent on arrival, but easy to fix.
Anonymous
Mar 28, 2026
Rating: 5/5
Solid hardware
The PCB looks clean and the soldering is good. No issues with noise in the analog signal. Highly recommend for anyone building IoT air quality nodes.
Anonymous
Mar 26, 2026
Rating: 5/5
Reliable gas detection
I use this in my workshop to detect fumes. The digital output triggers my exhaust fan reliably when gas levels rise. Very satisfied with the purchase.
Anonymous
Mar 13, 2026
Rating: 4/5
Good value but needs patience
The module is well-built and the potentiometer allows for easy threshold adjustment. Just remember it needs at least 24 hours of preheating before accurate readings can be taken.
Anonymous
Mar 10, 2026
Rating: 5/5
Great for university projects
Bought this for a final year environmental monitoring project. Documentation online is plentiful, and the sensor integrates easily with standard libraries.
Anonymous
Mar 10, 2026
Rating: 5/5
Perfect for my home air monitor project
This sensor works exactly as described. I connected it to an Arduino Uno and had readings within minutes after the initial burn-in period. Great sensitivity to smoke and alcohol vapors.
Q: Is the output voltage 3.3V or 5V compatible?
A: The module operates on 5V. The digital output is TTL compatible (0-5V). If using with a 3.3V microcontroller like ESP32, a voltage divider may be needed for the signal pin.
Q: Does this module come with the heating element pre-installed?
A: Yes, the MQ-135 sensing element and heater are fully assembled on the PCB. You only need to connect power and signal wires.
Q: How do I adjust the sensitivity threshold?
A: There is a blue potentiometer on the board. Rotate it clockwise to increase sensitivity (lower threshold) or counter-clockwise to decrease it. Use a multimeter or LED test to verify.
Q: What is the warm-up time required before calibration?
A: We recommend a preheat time of 24 to 48 hours for the first use to stabilize the internal heater and ensure accurate baseline readings.
Q: Can this sensor detect Carbon Monoxide (CO) specifically?
A: The MQ-135 is sensitive to a broad range of gases including CO, but it is not specific to CO alone. For dedicated CO detection, an MQ-7 sensor is recommended.
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