: rgb(33, 33, 33);  Connect the sensor to the application circuit. b. Turn on the power, keep preheating through electricity over 48 hours. c. Adjust the load resistance RL until you get a signal value which is respond to a certain carbon monoxide concentration at the end point of 90 seconds. d. Adjust the another load resistance RL until you get a signal value which is respond to a CO concentration at the end point of 60 seconds . SPECIFICATIONS A. Standard work condition Symbol Parameter name Technical condition Remark Vc circuit voltage 5V+-0.1 Ac or Dc VH (H) Heating voltage (high) 5V+-0.1 Ac or Dc VH (L) Heating voltage (low) 1.4V+-0.1 Ac or Dc RL Load resistance Can adjust RH Heating resistance 33?+-5% Room temperature TH (H) Heating time (high) 60+-1 seconds TH (L) Heating time (low) 90+-1 seconds PH Heating consumption About 350mW Parts Materials 1 Gas sensing layer SnO2 2 Electrode Au 3 Electrode line Pt 4 Heater coil Ni-Cr alloy 5 Tubular ceramic Al2O3 6 Anti-explosion network Stainless steel gauze (SUS316 100-mesh) 7 Clamp ring Copper plating Ni 8 Resin base Bakelite 9 Tube Pin Copper plating. Pack of 1Model NumberMQ7 Gas Sensor - Carbon Monoxide (CO),Minimum Sensing Range20,Maximum Sensing Range2000,Power Requirement5V+-0.1,Power Consumption0.0035 W,Maximum Operating Temperature55 degC,Minimum Operating Temperature-20 degC,Other FeaturesDetecting range : 20ppm-2000ppm carbon monoxide,Relative humidity : Less than 95%RH,Heating consumption : About 350mW,Heating Resistance : 33? +- 5%,Circuit Voltage : 5V,High sensitivity to carbon monoxide * Stable and long life,