怎样使用MQ-3酒精传感器

How to Use the MQ-3 Alcohol Sensor

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The MQ-3 alcohol sensor is useful for projects that tests levels of

alcohol, benzine, hexane or LPG in the air but it is most

popularly used as a breathalyzer (breath analyzer) for someone

who drank beer, wine or other liquor. Learn how to use this

sensor in this tutorial.

Introduction

Blood alcohol level (BAC) is normally measured in grams per

deciliter (g/dL). 1 g/dL is equivalent to 10000 ppm. In the US and

Canada, the minimum BAC for driving is 0.08 g/dL or 800 ppm.

In most European countries, it’s 0.05 g/dL or 500 ppm.

Note that the graph was derived with a load of 4.7 kΩ. It would

be difficult to replicate the results of the graph if we will be using

the MQ-3 as a breathalyzer. Instead, we will be using the Rs/R0

graph:

Here we see the different curves for each gas the MQ-3 can

detect in a*log-log plot. Rs is the resistance of the sensor at

Therefore, if we can determine the value of Rs in clean air, we

can also determine R0 and ultimately Rs/R0.

The MQ-3 alcohol sensor breakout board has four pins as

shown: