Model: FC-22-A - Quantity: 1 - Color: Blue + silver - Material: PCB - Sensitive material of MQ-2 gas sensor is SnO2 which is with lower conductivity in clean air. When the target combustible gas exist The sensors conductivity is more higher along with the gas concentration rising; Please use simple electrocircuit Convert change of conductivity to correspond output signal of gas concentration - MQ-2 gas sensor has high sensitive to LPG Propane and Hydrogen also could be used to Methane and other combustible steam it is with low cost and suitable for different application - Using high-quality dual-panel design with a power indicator and TTL signal output instructions; With a the DO switch signal (TTL) output and AO analog signal output; TTL output valid signal is low level; (When the low level output signal lights it can be connected directly to the microcontroller or relay module) - 0~5V analog output voltage the higher the concentration the higher the voltage; Carbon monoxide detector better sensitivity; There are four screw holes for easy positioning; With a long life and reliable stability; Rapid response and recovery characteristics - Operating voltage: DC 5V - Explanation: Use Preheat 20S - The first step: to the module for 5V DC (note the positive and negative do not reverse otherwise easily burned chip). - The second step: If you select the output end of the high and low DO TTL output signal can be connected directly to a microcontroller IO port or connect to the relay module potentiometer is used to adjust the output level transition threshold. - The third step: If you choose to AO analog output so you do not have control potentiometer AO feet directly connected to the input of the AD converter or microcontroller with AD can. According to our experience: In a normal environment namely: the environment of the measured gas setting the sensor output voltage value of the reference voltage At this time the voltage of the AO end about 1V when the sensor detects that the gas to be measured when the voltage of each elevated 0.1V the actual measured gas concentrations 200ppm (simple: 1ppm = 1mg/kg = 1mg / L = 10-6 commonly used to indicate the gas concentration or the concentration of the solution.) on the basis of this parameter can microcontroller inside the measured analog voltage value is converted to concentration values. Note: If you are used to do a precision instrument please buy the standard calibration instrument market or there is an error because the ratio of the output concentration and voltage relationship is linear but tends to be linear - Special note: the sensor is powered Preheat 20S stable measurement data sensor fever is a normal phenomenon because the internal heating wire if hot is not normal - Packing List: - 1 x MQ-2 sensor module