This hobby fun project creates an open source breathalyzer with MQ-3 analog sensor module, mini I2C OLED display (SSD1306), an Arduino sketch for the open source hardware ANAVI Gas Detector and LEGO® Medium Creative Brick Box 10696.
MQ-3 is a low-cost analog sensor module for detecting alcohol. The disadvantage is that is that it is not very accurate and requires calibration. The pre-heat time is over 24 hours.
ANAVI Gas Detector is an ESP8266-powered Wi-Fi dev board for monitoring air quality and detecting dangerous gases. It has been created with KiCad and has been certified as open source hardware by OSHWA. Although ANAVI Gas Detector has been designed for MQ-135 analog sensor module for measuring indoor air quality and detecting dangerous gases, it is also supports MQ-3.
The do it yourself breathalyzer created in this project is just for fun. It is not very accurate. It is provided "as is" without any warranty. Drink responsibly. Never drink and drive!
Function detectAlcohol reads data from the pin connected to the analog output of MQ-3. Depending on the retrieved data and hardcoded threshold values, text is displayed on the mini OLED display.
Building a case with LEGO bricks
ANAVI Gas Detector is placed on a big green LEGO® plate. LEGO® bricks are placed around it in a way to keep it in the same position. There is a whole for micro USB cable and placeholders for the mini OLED display and the MQ-3 sensor module.