Uploaded August 2016 | Updated September 2026, 2 weeks ago

---

You can find the code + schema on project page, below is the link:
arduino-projects-free.blogspot.com/2017/04/arduino-uno-gas-sensor-4-digit-7.html
Arduino uno - sensor gas MQ-4 Displayed on 4 Digit 7 segment
sensor gas with 4digi 7segment arduino uno