@epierre

Thanks for fast reply! I think i understand all but point #4... What do you mean by the Ro needs to be tuned to 10k? Using the adjustable resistor? Does that mean that the calibration number in fresh air at startup should ideally reach a set number, 10k?

Since I don't have access to properly calibrate the sensor against a know quantity of gas, I thought the rough calibration would occur in clean air at start up, is that correct?

Sorry for all the questions, it's a bit complicated. Thanks again!

Hi All. Very interesting stuff, thanks all for sharing! I'm attempting to integrate an MQ-2, MQ-6 and MQ-135 (sensors only, no boards) using parts of epierre's sketch but I'm confused on a few things on how to set it up properly:

1. What resistor(s) should go between A0 and ground? Keep in mind I'm not using a sensor board with built in protection resistor. Should there be a protection resistor then an adjustable pot for calibration?
2. define RL_VALUE (5)
   -- does this refer to the size of the protection resistor between A0 and ground?
3. define RO_CLEAN_AIR_FACTOR (9.83)
   -- does this value need to change at all?
4. float Ro4 = 2.511;
   -- when you say this needs to be tuned to 10k, does that mean put a pot between A0 and ground and adjust until the calibration R0 is 10k?

Sorry for all the questions, I appreciate any input! Thanks!