Carbon Monoxide & Flammable Gas Sensor MQ-9

This semiconductor petrol sensor detects the presence of Carbon Monoxide at concentrations from 10 to 1,000 ppm and combustible petrol from 100 to 10,000 ppm. The sensor’s simple analogue voltage interface requires only one analogue input pin from your microcontroller.

AUD$ 9.95

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We can ship 6 more in 7-10 days

Our Code: SKU-002625

Supplier Link: [Pololu MPN:1483]


Gas sensor with orange plastic case with quarter for size reference


This Carbon Monoxide (CO) and flammable petrol sensor detects the concentrations of CO and combustible petrol in the air and ouputs its reading as an analogue voltage. The sensor can measure concentrations of CO from 10 to 1,000 ppm and flammable petrol from 100 to 10,000 ppm.The sensor can operate at temperatures from -10 to 50°C and consumes less than 150 mA at 5 V. Please read the MQ9 datasheet (180k pdf) for more information about the sensor.

Gas sensor with orange plastic case bottom view


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 analogue 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 20 kΩ.

We 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


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