Mq7 Module for Accurate CO reading

Other Hardware Sensors
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Hi everyone!:smiley:

I've been working on a research project for my program. I wanted to measure the air quality of the surroundings of our region. I plan to measure Carbon Monoxide levels and Particulate matter.

My problem now is how to measure the CO levels. I am using the MQ7 module which is the MQ7 sensor itself and it's circuit board which includes a comparator circuit for the digital output. I don't need the digital output though, I need the analog outputs to compare the readings of different locations in our regions. I saw the datasheet for the MQ7 sensor itself and it was more complicated than I thought.

I needed to activate the sensor's heater by plugging it to 5 volts for 60 seconds, then pullung it down to 1.4 volts for 90 seconds. The measuring window is the last few seconds before pulling it down to 1.4 volts. I was able to make a circuit using a single MOSFET that could make the arduino switch the MQ7 module power from 5 to 1.4v. But the problem is, whenever it pulls down to 1.4v the module LED indicator switches off. There is no enough power to sustain the module; and therefore I cannot measure it.

How can I properly use the MQ7 module for this project? Looking forward to your kind responses😊. Thank you very much

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image3024×4032 3.12 MB

Here is my schematic. I apologize for the poor quality.

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The MQ7 cannot be used to accurately measure CO, as it is completely uncalibrated, unstable, and responds to several other gases, such as methane, LPG, H2, etc.

If you are serious about accurately measuring CO, buy a detector that is specific for CO.

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Thanks for your reply😃. I understand the issue about this. I also am planning to consider other sensors for this application. Thank you

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