Air quality monitor (MQ 5/7/135 based)

An ESP8266 mini based air quality monitor.

Please note that this should never be used to replace a proper CO monitor and should be used for informational purposes only.


  • Wemos D1 mini (
  • MQ 5 sensor
  • MQ 7 sensor
  • MQ 135 sensor
  • ADS1115 ADC Analog to Digital Converter (
  • M2.5 brass inserts (
  • M2.5 screws and nuts (
  • Hook up wire
  • Heat shrink


Print settings

  • Printer: Creality Ender 3v2 Neo
  • Filament: Creality PLA – Grey
  • Bed temperature: 60’c
  • Nozzle temperature: 200’c
  • Infill: 20%

Build/installation guide

Step 1 – Once printed, insert the 14 x M2.5 brass insert nuts

Step 2 – Use M2.5 screws to mount the MQ 5/7/135 sensors, analog to digital converter and Wemos D1 mini.

Step 3 – Solder everything together.

Step 4 – Print the lid and pop it on. Connect the Wemos D1 mini to your computer via USB so you can upload your firmware. I used ESPHome.

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