Attributes

Brand	-
Category	Robotics / STEM Teaching Tools / Sensors
Origin	-
Model Number	MQ-135
Detection Gases	Ammonia, Sulfide, Benzene, Smoke, CO2
Operating Voltage	5V DC
Output Signal	Analog and Digital (TTL)
Heater Voltage	5.0V ± 0.2V
Load Resistance	Adjustable via Potentiometer
Preheat Time	Over 24 hours for stability
Interface Type	3-Pin Header (VCC, GND, OUT)
PCB Dimensions	32mm x 20mm
Application	Air Quality Monitoring Systems

6 reviews

Anonymous

Mar 31, 2026

Rating: 4/5

Good value but needs calibration

The module is well-built and the potentiometer makes it easy to adjust sensitivity. Just remember it takes a day or two to stabilize readings accurately.

Anonymous

Mar 27, 2026

Rating: 5/5

Perfect for ventilation control

Integrated this into my greenhouse ventilation system to monitor ammonia levels. It has been running continuously for weeks without issues.

Anonymous

Mar 26, 2026

Rating: 3/5

Works but gets hot

The sensor functions correctly, but the heating element gets quite warm, which is normal for this type but worth noting for enclosed cases.

Anonymous

Mar 24, 2026

Rating: 5/5

Reliable gas detection

I used this to detect smoke and cooking fumes in my kitchen prototype. It reacts quickly to changes in air quality. Highly recommended for hobbyists.

Anonymous

Mar 17, 2026

Rating: 5/5

Great for Arduino projects

This sensor works perfectly with my Arduino Uno. The analog output is stable after the initial preheat time. Easy to integrate into home air quality monitors.

Anonymous

Mar 16, 2026

Rating: 4/5

Solid performance

Works as described. The digital output threshold is adjustable which is a nice feature. Make sure you have a proper 5V power supply.

5 FAQ

Q: How long does the preheat time really need to be?

A: For accurate and stable readings, we recommend a preheat time of at least 24 to 48 hours. Initial readings may fluctuate significantly before this period.

Q: Can this detect Carbon Monoxide (CO)?

A: The MQ-135 is primarily sensitive to Ammonia, Sulfide, and Benzene. While it has some sensitivity to CO, the MQ-7 sensor is specifically designed for Carbon Monoxide detection.

Q: Is the library available for Raspberry Pi?

A: Yes, since it outputs an analog signal, you will need an ADC (Analog-to-Digital Converter) chip like the MCP3008 to interface with the Raspberry Pi GPIO pins.

Q: What is the lifespan of the heating element?

A: Under normal operating conditions, the heating element typically lasts for several years. Continuous operation within the specified voltage range ensures maximum longevity.

Q: Does this module work with 3.3V microcontrollers like ESP32?

A: Yes, but you may need a voltage divider or level shifter for the output signal since the sensor operates at 5V. The heater specifically requires 5V.

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