اسم المنتج
MQ138 VOC (Volatile Organic Compound) Gas Sensor Module
وصف المنتج
The MQ-138 sensor contains tin dioxide (SnO2), which has a smaller conductivity in clean air. When there are VOCs like, ethylene glycol, benzene formaldehyde, tetrachloroethylene, toluene, methylene chloride, the conductivity of the sensor becomes higher.
المواصفات
- Dual signal output (Analog output and TTL Level output)
- TTL output effective signal is low. When the output is low, the signal light is on. Can be connected to single-chip Microcomputer IO Mouth)
- Analog output increases with concentration. The higher the concentration, the higher the voltage.
- It has high sensitivity for formaldehyde – suitable for the detection of aldehydes, alcohols, ketones, and aromatic compounds. Test concentration range of gas sensors:
- Benzene 1 to 100ppm
- Toluene 10 to 100ppm
- Methanol 5 to 100ppm
- Alcohol 30 to 300ppm
- Acetone 10 to 300ppm
- Formaldehyde 1 to 10ppm
- It has long-term service life and reliable stability.;
- Fast response recovery features
- With mounting hole. Easy to fix and install;
- Probe plug-in design. Convenient Test。
| Pin Number | Pin Name | Description |
| 1 | Vcc | The [in is there to power the module, requires 5V |
| 2 | Ground | To connect the module to the system’s common ground |
| 3 | Digital Out | Digital output pin, the Threshold value can be set by using the potentiometer |
| 4 | Analog Out | Analog output pin. Analog voltage based on the concentration of the gas |
MQ138 Pinout

التطبيقات
Domestic VOC gas alarm
Domestic VOC gas alarms use sensors to monitor the VOC pollutants which are toxic to human health. And, for this purpose, the device uses a microcontroller with an MQ-138 sensor.
Industrial VOC Gas Leakage alarm
In this Gas Alarm, If the device recognizes the level of gas in the air that outstrips the safety level of the environment. it will immediately activate the
alarm to warn the people working in the industry of the abnormal condition so that they will take necessary actions.
Portable VOC gas Detector
We use the term Portable gas detection for gas detectors that are carried by an individual being. Generally, battery-operated requires sensors. We use portable monitors for toxic or combustible gas detection, and hence -138 is a brilliant use.










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