after review of some work with MQ7 sensor,an some lack in their schematic for preparing LOW and HIGH voltage of sensor heater, i have tested this circuit.
this circuit use 5 diode for preparing low voltage in off state of sensor. this method is inexpensive and reliable for high current sensor.
i calibrate the sensor after one day of data acquisition.
after test of sensor, some figure has been prepared and more over schematic of my circuit.
all data has been attached.
releasev1_CODetector.zip (979 KB)