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Alcohol Gas Sensor MQ-3

SKU: POLOLU-1634 Brand: Pololu
This semiconductor gas sensor detects the presence of alcohol gas at concentrations from 0.04 mg/L to 4 mg/L, a range suitable for making a breathalyser. The sensor’s simple analog voltage interface requires only one analog input pin from your microcontroller.
$8.40 AUD, inc GST
$7.64 AUD, exc GST

Quantity Discounts:

  • 10-25 $7.33 (exc GST)
  • 25+ $7.10 (exc GST)

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This alcohol gas sensor detects the concentration of alcohol gas in the air and ouputs its reading as an analog voltage. The concentration sensing range of 0.04 mg/L to 4 mg/L is suitable for breathalysers (the legal limit of breath alcohol concentration, or BrAC, in most Pololu states is 0.08 grams per 210 liters, or 0.38 mg/L). The sensor can operate at temperatures from -10 to 50°C and consumes less than 150 mA at 5 V. Please read the MQ3 datasheet (153k pdf) for more information about the sensor.

Gas sensor with orange plastic case bottom view.

Connections

Connecting five volts across the heating (H) pins keeps the sensor hot enough to function correctly. Connecting five volts at either the A or B pins causes the sensor to emit an analog voltage on the other pins. A resistive load between the output pins and ground sets the sensitivity of the detector. Please note that the picture in the datasheet for the top configuration is wrong. Both configurations have the same pinout consistent with the bottom configuration.The resistive load should be calibrated for your particular application using the equations in the datasheet, but a good starting value for the resistor is 200 kO.

Pololu offer two breakout boards that make it easier to interface with these sensors: a Pololu carrier board and a SparkFun carrier board. The Pololu version is shown below.

Pololu MQ gas sensor carrier with sensitivity-setting resistor soldered in the vertical orientation.

Note: These sensors could have orange or blue plastic cases. There is no functional difference between the two colored cases.

This product is listed in:

Sensors>Gas & Smoke

Product Comments

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We deliver Australia-wide with these options (depends on the final destination - you can get a quote on the view cart page):

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Non-metro addresses in WA, NT, SA & TAS can take 2+ days in addition to the above information.

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