Hey again guys. I'm having a bit of a problem with my gas sensors I'm using for my thesis project, which is due tomorrow :o. The problem than I'm having is that the output of these sensors increases logarithmically in proportion to the concentration of gas it detects. I'll post the specs.
http://www.parallax.com/Portals/0/Downloads/docs/prod/sens/MQ-2.pdf
http://www.parallax.com/Portals/0/Downloads/docs/prod/sens/MQ-7.pdf
http://www.parallax.com/Portals/0/Downloads/docs/prod/sens/MQ-5.pdf
tl;dr for sensors...
CH4: Rs(current resistance)/Ro(ambient condition resistance) varies from 2 to 0.7 in logarithmic proportion to 100 to 10,000ppm
LPG: Rs(current resistance)/Ro(ambient condition resistance) varies from 0.7 to 0.15 in logarithmic proportion to 200 to 10,000ppm
CO: Rs(current resistance)/Ro(ambient condition resistance) varies from 1.7 to 0.1 in logarithmic proportion to 50 to 4,000ppm
Is there a function I can use(in either VB6 or Arduino codesets) that would sort this out neatly for me?