MQ138 Gas Sensor Module (Aldehydes, Alcohols, Ketones , Formaldehyde ) MQ-138 (PCB สีเขียว)

MQ138 Formaldehyde Aldehydes Sensor Module  is sensor used for the detection of most of the volatile gases such as:

• Aaldehydes
• Alcohols
• Ketones
• Aromatic compounds
• Formaldehyde

Equiped with SnO2 sensitive sensor material which has higher sensitivity upon high gas concentration. The sensor can be used as breath alcohol detector, and etc.

The figure shows the connection of the MQ sensors to the Arduino

Features:

• Module with MQ138 gas sensor and circuitry to enable easy plug and use, just connect power and the module is ready to interface with microcontroller.
• Working voltage: DC 5V
• Comes with power and digital signal LED indicator
• 2-way signal output (analog output, and TTL-level output)
• TTL output valid signal is low; (low output signal light, which can be accessed microcontroller IO port)
• Analog output increases with the concentration, the higher the voltage the higher the concentration Aldehydes, alcohols, ketones, aromatic compounds with high sensitivity
• With a long life and reliable stability
• Fast response characteristics
• With mounting holes for easy permanent installation
• Main chip: LM393, formaldehyde-sensing probe
• Size: 35mm x 20mm x 28mm
• Weight: 14 g

Application:

• For home, volatiles environment detection means, be suitable for detection of aldehydes, alcohols, ketones, aromatic compounds, gas sensitive element concentration ranges: 
  • Benzene 1 to 100ppm
  • Toluene 10 to 100ppm
  • Methanol 5 to 100ppm
  • Alcohol 30 to 300ppm
  • Formaldehyde 1 to 10ppm
  • Acetone 10 to 300ppm

Packing List:

• 1 x MQ138 Formaldehyde Aldehydes Sensor Module

Resources:

• MQ-138 Datasheet
• Example of coding using Arduino by Electropeak: How to Calibrate and Use MQ9 Gas Sensor with Arduino the coding uses MQ9 gas sensor, however for each gas sensor (MQ series) the coding is just the same.
• Example of sensor calibration, by empierre from github, Arduino code.