Hello,
I've looked into this a bit, and here are my comments:
- The MQ-7 module is so poorly documented that it is not a great choice to work with
- There are other (qualitative) sensors (such as the mics5524) that seem simpler to work with, and don't appear to have any clear disadvantage vs. the MQ-7.
- If I were to take the time to calibrate the MQ-7 fully, it would only really be of use to me. Unless I mapped out the entire RH, temperature, CO concentration, and interfering gases profile, it is unlikely my results would be directly applicable to anyone else. Additionally, even if I did so, anyone looking to make quantitative measurements would (hopefully) repeat some of my results under their exact conditions with their own sensor to ensure they got the same data. By the time this was complete, their own data would be more useful for them than what I could provide.
- In case it is of help to anyone, I am posting the circuit that was suggested by Leo. I have built this circuit, and it worked exactly as expected (thanks Leo). While I did physically build the circuit, for this group, I am also posting the results of the circuit simulation in case anyone finds it useful.
Finally, for anyone reading this in the future, my final suggestion is simply to not use this sensor, as it is needlessly painful to work with, and poorly documented.
Thanks,
Dustin
