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{\"mobile_description\":\"Enhance your air quality projects with the 3Pcs MQ-135 Gas Sensor Module! Ideal for Arduino and ESP8266, this sensor detects NHâ, NOx, alcohol, benzene, smoke, and COâ, making it perfect for indoor monitoring and HVAC control. Enjoy fast response times with dual outputs (analog and digital TTL) for flexible integration. Each module features an adjustable threshold and clear indicator LEDs for real-time response. With a simple 4-pin connection, you can easily incorporate these sensors into your smart home automation or educational projects. Experience superior air quality detection; order now and breathe easy! Fast free US shipping available.\"}
Electronics for IoT, Prototyping & DIY
{\"mobile_description\":\"Enhance your air quality projects with the 3Pcs MQ-135 Gas Sensor Module! Ideal for Arduino and ESP8266, this sensor detects NH₃, NOx, alcohol, benzene, smoke, and CO₂, making it perfect for indoor monitoring and HVAC control. Enjoy fast response times with dual outputs (analog and digital TTL) for flexible integration. Each module features an adjustable threshold and clear indicator LEDs for real-time response. With a simple 4-pin connection, you can easily incorporate these sensors into your smart home automation or educational projects. Experience superior air quality detection; order now and breathe easy! Fast free US shipping available.\"} 3 Pieces (3X) MQ-135 NH₃ / NOx / Alcohol / Benzene / Smoke / CO₂ Air Quality Gas Sensor Detector Modules
The MQ-135 gas sensor detector module is designed for air quality monitoring, detecting ammonia (NH₃), nitrogen oxides (NOx), alcohol, benzene, smoke, and carbon dioxide (CO₂). The module features dual signal outputs -- an analog output (0–5V) proportional to gas concentration and a digital TTL output with an adjustable threshold via the onboard potentiometer. With fast response, long service life, and a simple 4-pin interface, it\'s ideal for Arduino-based air quality projects, smart ventilation systems, and indoor environment monitoring.
⚠️ Important: The sensor element gets hot during operation -- do not touch the metal mesh cylinder while powered. Allow a 24–48 hour initial burn-in for best accuracy on first use; subsequent warm-ups take only 2–5 minutes. 🔧 How It Works
- The sensor\'s internal heater raises the tin dioxide (SnO₂) element to its operating temperature
- When target gas molecules (NH₃, NOx, alcohol, benzene, smoke, or CO₂) contact the heated surface, the sensor\'s electrical resistance decreases
- The onboard voltage divider converts the resistance change into an analog voltage (0–5V) on the AO pin -- higher concentration produces higher voltage
- The LM393 comparator compares the analog signal against the potentiometer threshold -- when exceeded, the DO pin goes HIGH and the DO LED illuminates
⚡ Key Features
- Air Quality Monitoring -- Detects NH₃, NOx, alcohol, benzene, smoke, and CO₂
- Broad-Spectrum Detection -- Responds to toxic gases, volatile organic compounds (VOCs), and smoke
- Dual Signal Output -- Analog (AO) and digital TTL (DO) outputs for flexible integration
- Adjustable Threshold -- Onboard potentiometer to set the digital output trigger level
- Indicator LEDs -- Power LED and DO status LED for visual response
- Fast Response & Recovery -- Quick detection and return to baseline
- Simple 4-Pin Interface -- VCC, GND, AO, DO -- no library required
- 5V Compatible -- Works directly with Arduino, ESP8266, and other 5V development boards
📐 SpecificationsOperating Voltage5V DCMax Power Consumption800 mW (160 mA at 5V)Detectable GasesNH₃, NOx, alcohol, benzene, smoke, CO₂Analog Output (AO)0V to ~5V (proportional to gas concentration)Digital Output (DO)TTL level -- LOW normally, HIGH when gas detectedThreshold AdjustmentOnboard potentiometerIndicator LEDsPower LED, DO (Digital Output) LEDDimensionsApprox. 32 × 20 × 27 mm (1.25 x 0.8 x 1.1 inches) L × W × HWeight~7 grams 📦 What\'s in the Box
- 3x MQ-135 Air Quality Gas Sensor Detector Module
Arduino, jumper wires, and USB cable are not included.
🔌 Compatible With
- Arduino (Uno, Mega, Nano, Pro Mini, and compatibles)
- ESP8266 and ESP32 development boards
- Raspberry Pi (with ADC module for analog reading)
- STM32, Teensy, and other 5V-compatible microcontrollers
🎯 Typical Applications
- Indoor air quality monitoring (homes, offices, classrooms)
- Smart ventilation and HVAC control
- Ammonia detection in agricultural and livestock facilities
- Solvent and VOC monitoring in workshops and labs
- Smoke detection as a secondary indicator
- CO₂ trend monitoring (general indication)
- Air quality dashboards and IoT data logging
- Smart home automation -- trigger alerts, fans, or air purifiers
- Educational and STEM projects
💡 Tip: The MQ-135 is a broad-spectrum air quality sensor -- it cannot distinguish between individual gas types on its own. For precise CO₂ measurement, pair it with a dedicated NDIR CO₂ sensor. For gas-specific detection, consider using it alongside other MQ-series sensors (MQ-2 for smoke, MQ-7 for CO, MQ-5 for natural gas) and comparing readings. ⚠️ Important Notes
- The sensor element gets hot during operation -- do not touch the metal mesh cylinder while powered
- Allow a 24–48 hour initial burn-in for best accuracy on first use
- Raw analog readings are not direct PPM values -- calibration against known concentrations is required for PPM conversion
- The sensor draws up to 160 mA -- use an external 5V supply if powering multiple sensors or experiencing unstable readings
- Temperature and humidity can affect sensor readings -- recalibrate periodically for best results
- Benzene is a known carcinogen -- do not intentionally expose yourself to benzene vapors for testing
- Keep the sensor away from direct airflow (fans, HVAC vents) that could dilute gas concentrations
🏪 About Envistia Mall
Envistia Mall is a US-based electronics retailer specializing in development boards, sensors, modules, and components for makers, engineers, and educators. We are committed to providing quality products with excellent customer service.
📦 Fast Free US Shipping | 🔄 Hassle-Free Returns | 📧 Responsive Customer Support
Visit our store for more gas sensor modules, Arduino-compatible sensors & development boards, and electronic components for your next project.
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