During the First Meeting of Electronic Arts in Florianópolis, we built a Breathalyzer using the Alcohol Gas Sensor MQ-3 and a Arduino Board to use in the last day of the meeting, in which we gave a party. You can see a quick video two posts below. Last days I received many emails asking for the code or how to make one, so I decided to build the sensor again, take pictures/videos and make a tutorial showing how you can make one, so here it is.
Parts Needed:
- Arduino Board
- 10x 5mm LEDs (Green, Yellow and Red)
- 100KΩ Potentiometer (to calibrate the sensor)
- 10x ≈ 220Ω Resistor (anything between 220Ω and 470Ω is OK)
- BreadBoard
- MQ-3 Sensor from Sparkfun
Here are some pictures from the building process:
To make the LEDs work, I have connected them in sequence using the Digital Pins 2 till 11 (ten LEDs total). Remember to use a resistor between 220Ω and 470Ω for each LED, like shown on the picture below:
To connect the sensor, you have to connect one of the H pin to +5V Supply (use an external power supply for that, it may be too much current for the arduino) and the other one to Ground.