I have a MQ135 gas sensor from keyestudio, and a light sensor from a chinese manufacturer. They are both on their own PCB with resistors, small eeprom and a variable pot.
Turning the variable pot fine tune the calibration of the sensor, but is there anyone who could explain me exactly what is it doing? Does it have an effect on signal amplification? or only adding more or less resistance to the signal output by the light sensor in order to fine tune the reading ?