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Topic: CONVERTING ANALOG OUT OF MQ-7 TO PPM (Read 2 times) previous topic - next topic

vhenamae

Hi guys..
Can somebody help me how to convert the voltage out of MQ-7 to ppm? I already do the cycle time,interface it in arduino board and received a analog out from the sensor.But the problem is i dont know to convert those output to a useful one or ppm values.can somebody help me or give me an idea?

RIDDICK

hi!

is it this one:
http://www.sparkfun.com/datasheets/Sensors/Biometric/MQ-7.pdf
?

did u heat it properly?

then u need to measure the resistance of the A and B pins...
u can do it in 2 ways:
1.
send a known current through it (e. g. 50uA) and measure the voltage at the A and B pins...
2.
send a known voltage via a known series restistor through it (e. g. 100kOhm) and measure the voltage at the A and B pins...

have fun...  :)
-Arne

vhenamae

yes.im using that one.you mean preheating the sensor in 5v(60sec) and 1.4v(90sec)? or preheating it with 5v in less than 48 hours? the A and B pins of the sensor? thanks for your reply.. :)

RIDDICK

1.
i think for moderate accuracy preheating with 60sec@5V should be sufficient...
2.
yo... A and B...
-Arne

vhenamae

thanks. do you have any code?or idea? coz i will display it in LCD.

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