Circuit design advice for MQ-3 alcohol gas sensor and analog panel meter

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1

Hello, I have a circuit design question about hooking up the MQ-3 alcohol gas sensor directly to an 0-5V analog panel meter without a microcontroller inbetween. If I condition an external battery using a 5V regulator can I connect the battery everywhere it says 5V in this wiring diagram and then connect the "to analog input pin" sensor terminal to the analog panel meter's voltage in terminal?

The goal is to make a simple (non-calibrated) analog breathalyzer. Thanks for the help, I've never had any training in circuits.

Mike

2

Hi Mike,

The datasheet for this sensor is here: http://www.jk-sensor.com/UserFiles/File/GAS/MQ-3.pdf

Basically this is a variable resistance device (A heated surface-chemistry bead)...

The output voltage will vary from air to alcohol etc, but NOT fullscale 5 volts. You will see a variation around the midscale of a 5V meter but not a LOT of change.

You would need an operational amplifier etc. to get 0 to 5v output for the change in sensor output. Or Fix It In Software with an Arduino...