Hi guys , im going to apply MQ-2,4,6,7 for my project using an Arduino Mega board. However, does anyone know how to calibrate different gases (ppm)from the sensor since the sensor that i using is a module.
I did some looking and found this reference guide on how to interface MQ sensors with an Arduino. Give it a read and see if it is helpful. The article is not specific on which sensor, but gives a good flow on how to identify your sensor, and what steps to take.
Yup , i saw this before also, but it doent teach us how to convert the analogue value to the ppm value.
Those sensors are not factory calibrated. The proper way to calibrate them is to measure several known concentrations.
For some models you can guess the calibration by measuring a 0% concentration. Does your sensor datasheet show relative resistance at various concentrations?