Attributes

Brand	-
Category	Robotics / STEM Teaching Tools / Sensors
Origin	-
Sensor Type	MQ-135 Semiconductor Gas Sensor
Detection Gases	Ammonia, Sulfide, Benzene, Smoke, CO2
Operating Voltage	5V DC
Output Signal	Analog (AO) and Digital (DO)
Preheat Time	24-48 Hours for Stability
Interface	3-Pin Header (VCC, GND, OUT)
PCB Dimensions	32mm x 20mm
Adjustable Sensitivity	Yes, via Onboard Potentiometer
Compatibility	Arduino, Raspberry Pi, ESP32, STM32
Package Includes	1x MQ-135 Module, 1x Pin Header Set

6 reviews

Anonymous

Mar 30, 2026

Rating: 5/5

Excellent for learning electronics

Bought this for a university project on environmental monitoring. The documentation online is plentiful, and the hardware is robust. It easily interfaces with standard microcontrollers.

Anonymous

Mar 26, 2026

Rating: 5/5

Perfect for my smart home project

This sensor works flawlessly with my Arduino setup. The analog output is stable after the initial preheat period, and it detects smoke from a distance effectively. Great value for the price.

Anonymous

Mar 23, 2026

Rating: 4/5

Good sensitivity, needs calibration

The module is responsive to changes in air quality. I had to spend some time calibrating the potentiometer to get the digital trigger just right for my greenhouse ventilation system, but once set, it works well.

Anonymous

Mar 22, 2026

Rating: 5/5

Reliable alarm trigger

I integrated this into a workshop safety alarm. It reliably triggers the buzzer when soldering fumes are present. The digital output makes integration very simple without complex coding.

Anonymous

Mar 01, 2026

Rating: 4/5

Solid build quality

The PCB looks clean and the soldering points are solid. It took about a day to stabilize readings as recommended in the datasheet. Happy with the purchase for prototyping purposes.

Anonymous

Mar 01, 2026

Rating: 3/5

Works but gets hot

The sensor functions as described and detects gases accurately. However, the heating element gets quite hot during operation, so ensure you have adequate spacing in your enclosure. Otherwise, no complaints.

5 FAQ

Q: How do I adjust the sensitivity threshold?

A: There is a blue potentiometer on the back of the PCB. Rotate it clockwise to increase sensitivity (lower threshold) or counter-clockwise to decrease it. Test with a gas source while monitoring the DO LED.

Q: Does this module come with the connecting wires?

A: No, the package includes the sensor module and pin headers, but connecting wires are sold separately to allow for custom lengths.

Q: What is the warm-up time required before accurate readings?

A: For stable and accurate baseline readings, we recommend powering the sensor for at least 24 to 48 hours initially. Short-term tests can be done after 10 minutes, but precision will improve over time.

Q: Can this detect Carbon Monoxide specifically?

A: The MQ-135 is sensitive to a broad range of harmful gases including CO, but it is not specific to Carbon Monoxide alone. For dedicated CO detection, a specialized sensor like the MQ-7 is recommended.

Q: Is the output voltage 3.3V or 5V compatible?

A: The module operates on 5V. The analog output scales with the supply voltage. If using a 3.3V microcontroller like ESP32, please use a voltage divider on the analog output pin to prevent damage.

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