MQ-135 Air Quality Gas Sensor Module | Compoden
MQ-135 Air Quality Gas Sensor Module — Detects NH3, Benzene, Smoke, CO2
The MQ-135 is a semiconductor gas sensor module designed to detect a wide range of air pollutants including ammonia, benzene, alcohol, smoke, and CO2. It provides both analog and digital outputs, making it ideal for DIY air quality monitors and alarm systems. With a fast response time and high sensitivity, this sensor is a reliable choice for indoor environment sensing.
Key Specifications
| Specification | Value |
|---|---|
| Detection Gases | Ammonia, Benzene, Smoke, CO2, Alcohol, etc. |
| Operating Voltage | 5V DC |
| Heater Power Consumption | <800mW |
| Detection Range | 10–1000 ppm (gas-dependent) |
| Output Type | Analog (0–5V) and Digital (TTL threshold) |
| Preheat Time | 20–60 seconds |
What You Can Build With This
- Indoor Air Quality Monitor: Interface with an ESP8266 to send real-time pollution data to a cloud dashboard.
- Smoke/Fire Alarm: Build a standalone smoke detector that triggers a buzzer when thresholds are exceeded.
- Ammonia Leak Detector: Use in livestock farms or refrigeration plants to monitor harmful gas levels.
- Portable Pollution Tester: Combine with an OLED display and battery for handheld outdoor air quality checks.
Compatibility
The MQ-135 module operates at 5V logic, so it works directly with Arduino boards, ESP32, and Raspberry Pi (via an external ADC if using analog). Most 5V microcontrollers can read the analog output with a simple analogRead(). For 3.3V systems like Raspberry Pi Pico, use a logic level converter for the digital pin.
Wiring Notes
Connect VCC to 5V, GND to ground, AOUT to an analog input pin (e.g., A0 on Arduino), and DOUT to a digital pin if you need a simple threshold alarm. The sensor requires preheating for 20–60 seconds before readings stabilize. The digital output goes LOW when the gas concentration exceeds the potentiometer-set threshold.
Why Buy from Compoden
Every component is sourced from verified suppliers and tested for compatibility before listing. We've spent 10 years building projects for makers, schools, and institutions across India. Ships from Bengaluru in 3-5 days. If defective on arrival, replace within 7 days.
Is this compatible with Arduino?
Absolutely. Connect AOUT to any analog pin and read values with analogRead(). The digital pin can be used for simple threshold alerts.
Can it measure precise CO2 levels?
The MQ-135 is not selective; it responds to multiple gases. For accurate CO2 measurement, consider a dedicated NDIR sensor. However, it can detect relative changes in air quality.
How do I calibrate it?
Preheat the sensor for at least 24 hours initially. Then, in clean air, read the analog value as baseline. For gas-specific calibration, use a known concentration and adjust your code accordingly.
📦 Free Setup Handoff Document Included
Every Compoden order includes a free setup handoff document — step-by-step instructions to get your component working within minutes. Download it via QR code on your package. The handoff document is also trained to help you troubleshoot the majority of problems.
Ask Soldr above what you can build with this — it knows every Compoden kit this part appears in.
Shipping Information
- Prepaid Orders: ₹75 for orders up to ₹999, FREE shipping above ₹999
- COD Orders: ₹125 shipping + ₹50 COD fee = ₹175 total
- Delivery Timeline: Dispatch in 1-2 days, delivery in 2-7 days depending on location
Returns & Warranty
- 7-Day Return: Manufacturing defects only (approval required)
- Warranty: 7 days from delivery
- Non-Returnable: Batteries, consumables, cut wires, clearance items