ShillehTek MQ-135 air quality gas sensor module with metal mesh top

MQ-135 Air Quality Hazardous Gas Sensor Module for Arduino

Name: MQ-135 Air Quality Hazardous Gas Sensor Module for Arduino
Brand: ShillehTek
Price: 5.99 USD
Availability: InStock

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MQ-135 Air Quality gas sensor module for Arduino detects NH3, NOx, CO2 and VOCs to monitor indoor pollution; analog and digital outputs ideal for logging air quality or triggering ventilation.

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Overview

Product Overview

The MQ-135 Air Quality Hazardous Gas Sensor Module for Arduino uses a sensitive Tin Dioxide (SnO2) sensing layer that changes conductivity when exposed to polluted air, letting you monitor common indoor pollutants such as ammonia (NH3), nitrogen oxides (NOx), alcohol, benzene, smoke and CO2. The board provides both a linear analog output for logging concentration trends and a digital output driven by an onboard LM393 comparator for simple alarm thresholds, and it mounts on a standard 4‑pin header (VCC, GND, DO, AO) that fits breadboards and Arduino shields. It can be calibrated against clean‑air Ro values to estimate PPM and includes an active heater that needs an initial 24‑hour burn‑in to stabilize readings—practical for makers building monitors or ventilation controls.

Questions & answers

Frequently asked questions

Does the MQ-135 module work with Arduino?

Yes. It is designed for Arduino projects and exposes a simple analog output plus a digital comparator output, so an Arduino can read pollutant trends or monitor a threshold alarm using standard input pins.

Is the MQ-135 module ready for breadboards?

The board uses a standard 4-pin header labeled VCC, GND, DO, and AO, making it suitable for breadboards and Arduino shields. ShillehTek modules are sold pre-soldered, so basic jumper-wire setup does not require header soldering.

What signals does the MQ-135 module output?

It provides AO, a linear analog signal for logging gas concentration trends, and DO, a digital signal from the onboard LM393 comparator for threshold-based alarms. The connector also includes VCC and GND power pins.

Can this MQ-135 sensor build an air monitor?

Yes. It can monitor indoor air-quality trends involving ammonia, nitrogen oxides, alcohol, benzene, smoke, and CO2, making it practical for maker air monitors, data loggers, warning indicators, or ventilation-control experiments.

Why are MQ-135 readings unstable at first?

The sensor includes an active heater and needs an initial 24-hour burn-in before readings stabilize. For estimated PPM values, calibrate against a clean-air Ro reference rather than expecting accurate numbers immediately after power-up.

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What's included