MQ-7 sensor Carbon-monoxide Sensor

This Carbon Monoxide (CO) gas sensor detects the concentrations of CO in the air and ouputs its reading as an analog voltage. The sensor can measure concentrations of 10 to 10,000 ppm.The sensor can operate at temperatures from -10 to 50°C and consumes less than 150 mA at 5 V. There are two ways to read the output from the MQ-7. One is through the DOUT pin which gives a high when the concentration threshold is reached and low otherwise. The threshold can be varied by adjusting the trimmer on the breakout board which is Rp in the schematic. Meanwhile, the AOUT pin gives varying voltage representing the CO concentration. We can convert the voltage reading to ppm if we look at the characteristic curve above, which is a log-log plot.

Technical Specification

• Detection Zone:10 to 1000ppmm.
• Characteristic Gas:100ppmmco.
• Sensitive Resistance:2K to 20K in 100ppm co.
• Sensitivity:3%.
• Response Time:1s.
• RecoveryTime:30s.
• Heating Resistance:313.
• HeatingCurrent:180mA.
• Heating Voltage:5.0V0.2V /1.50.1V.
• HeatingPower: about 350mW.
• Conditions:Ambient Temperature:-20+50.
• Humidity:95%RH.
• Oxygen Content:21% .
• Size: 3.5cm X 2.2cm– 1.4inch x 0.9inch.