MQ135 Air Quality Gas Sensor Module
MQ135 overview
MQ135 gas sensor belongs to the MQ gas sensor series infamous for their quick and timely response corresponding to harmful concentration of dangerous gases. The MQ135 Gas sensor can detect gases like Ammonia (NH3), Sulfur (S), Benzene (C6H6), CO2, and other harmful gases and smoke. Similar to other MQ series gas sensors, MQ135 also has a digital and analog output pin. When the level of these gases goes beyond a threshold limit in the air the digital pin goes high. This threshold value can be set by using the onboard potentiometer. The analog output pin outputs an analog voltage which can be used to approximate the level of these gases in the atmosphere.
MQ135 gas sensor applies SnO2 which has higher resistance in clear air as a gas sensing material. When there is an increase in polluting gases, the resistance of the gas sensor decreases along with that. MQ135 offers a wide array of features such as ESD protection and overvoltage protection. The module is very simple to use and is easily interfaceable with almost every available microcontroller such as Arduino Uno, NodeMCU, Raspberry Pi, etc.
Key specifications
Datasheet
MQ135 features
- Wide detecting scope
- Fast response Time
- High Sensitivity
- Stable and long life
- The operating Voltage is +5V
- Detects and Measures NH3, NOx, alcohol, Benzene, smoke, CO2, etc.
- Preheat duration 20 seconds
- Can be used as a Digital or analog sensor
- The Sensitivity of the Digital pin can be varied using the potentiometer
MQ135 pinout
| Pin | Name | Description |
|---|---|---|
| 1 | VCC | This pin powers the module, typically the operating voltage is +5V |
| 2 | GND | Used to connect the module to the system ground |
| 3 | DO | You can also use this sensor to get digital output from this pin, by setting a threshold value using the potentiometer |
| 4 | AO | This pin outputs 0-5V analog voltage based on the intensity of the gas. |
MQ135 specifications
| Circuit voltage | 5V±0.1 |
|---|---|
| Heating voltage | 5V±0.1 |
| Load resistance | Adjustable |
| Heating consumption | less than 800mw |
| Using Temperature | -10℃-45℃ |
| Storage Temperature | -20℃-70℃ |
| Related humidity | less than 95%Rh |
| Oxygen concentration | 21%(standard condition) Oxygen concentration can affect sensitivity |
| Sensing Resistance | 30KΩ-200KΩ (100ppm NH3 ) |
| Concentration Slope rate | ≤0.65 |
MQ135 applications
- Air Quality alarms and early warning systems for Home, offices and industrial environment.
More about MQ135
Specifications
- Heater resistance 33Ω±5%
Datasheet
See Also: CD4059 Program Divide-by-N Counter | HMC5883L 3-Axis Magnetometer Module | DS3231 Precision I2C Real-Time Clock Module
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