I'm using the MQ-131 sensor on a arduino Yùn . I read the analog port via REST (bridge activated) for example it gives me "8".
the datasheet is here.
http://p.globalsources.com/IMAGES/PDT/SPEC/037/K1059654037.pdf
http://www.cooking-hacks.com/skin/frontend/default/cooking/pdf/MQ-131.pdf
This is a logarithmic relation to calculate the concentration of O3 in ppb :
log (Rs/Ro) = m log(ppb) + c
But how to have these parameters ? does-it means we have to calibrate it ?
this may be relevant
http://forum.arduino.cc/index.php?topic=225455.msg1634010#msg1634010
ooops this may help me : How can I convert AnalogRead to something useful? - Programming Questions - Arduino Forum
Same kind of sensor , but its on a module and i don't know the value of the resistance
start with a 100k potmeter. is series
adjust till you read approx 500 as analogRead
..as times runs (2 days) U'll have to adjust the pot again to read 511
(then you know that Rs=RL - which value this is, isnt relevant)
...
datasheet says that : Rs(in air)/Rs(in 50ppb O3)?3
This means that Rs drops to less than 1/3 when exposed to 50ppb
You analog reading will increase to 3/4 of full scale = 767
make a table based on reading from datasheet, or write your transfer function..
Well the following will be more usefull :
http://t.co/KxRLZA7bmm
This is the "module" it has some resistance and other componant on it: I don't know what they do.
It delivers value on the analog port, in my home from 4 to 10...
i connect mq131 to arduino uno.First i preheated the mq131 two days.First i start the program i measured approx 700in ambient air.After 2 days i measured approx 300 in ambient air.When i expose the ozone to the mq131 sensor it is decreasing suddenly to 1 or 0...Why?? is it working reverse? i couldnt understand it?Can you help me i am beginner.