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Topic: not getting an analog reading from my gas sensor (Read 385 times) previous topic - next topic

retrolefty

OK, I found this datasheet at sparkfun:

http://www.sparkfun.com/datasheets/Sensors/MQ-3.pdf

This sensor needs/has an internal heater of 33 ohms so the current draw for the sensor is at least 150ma which in my opinion is way to much for a standard small 9vdc battery. You are going to have to find a voltage source with better current capacity.

Lefty


encryptor

You are totally right!  Thanks for the help! 8) +1 karma for you!
peace*&^

encryptor

#7
Nov 12, 2012, 10:29 pm Last Edit: Nov 12, 2012, 10:30 pm by encryptor Reason: 1
Even though I can agree with your answer I see on Wikipedia that my Zinc Chloride (zinc carbon) battery has a typical 400 MAh rating.  That would make me think 150mA isn't all that much to draw from a 9V battery.

http://en.wikipedia.org/wiki/Nine-volt_battery
peace*&^

retrolefty


Even though I can agree with your answer I see on Wikipedia that my Zinc Chloride (zinc carbon) battery has a typical 400 MAh rating.  That would make me think 150mA isn't all that much to draw from a 9V battery.

http://en.wikipedia.org/wiki/Nine-volt_battery


You need to find out at what continuous current draw that 400 mah rating is given at. Mah ratings can be quite deceiving, they are more a marketing specification rather then a good technical specification. You need a stronger voltage source, that is the bottom line. If your 5vdc voltage regulator is not putting out +5 volts powering the sensor then the battery voltage is dropping under the load.

Lefty

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