Circuit Issue Interfacing Arduino with Gas Sensors and NodeMCU

Dear General Electronics Community,

Recently, I have been working on a project to sense pollutant concentrations in the atmosphere. The goal is to build 20 different modules and deploy them in local Primary Target Areas to report live data measurements.


  • Arduino Nano
  • NodeMCU WIFI Module
  • MQ-135 Gas Sensor
  • Figaro 2600 Gas Sensor
  • Figaro 2602 Gas Sensor
  • DHT11 Temperature and Humidity Sensor
  • 10Ω Resistor (2x)
  • 10KΩ Resistor (1x)
  • 6V AA Battery Pack (2x)

I have chosen to integrate all of the different components onto a PCB in order to maximize building efficiency. However, I believe that the circuit is faulty because the module’s temperature sensor displays values up to 40 degrees Celsius at room temperature. Moreover, my 6V battery pack powering the Arduino Nano and sensors barely last 8 hours. I am seeking guidance because I cannot seem to find the error in my circuit schematic and I was hoping this forum could help!

The files for my circuit schematics and sensor information are attached in a .zip file folder below.

Thank you for your help! Please let me know if you have any further questions!

Arduino Gas (547 KB)

FYI - most people here will not download zip files

See the post at the top of the forum on how to use the forum, insert images and post code using code tags

Please post images of the schematic and the board layout. Not everybody uses eagle.
It's probably better to attach datasheets individually (or post links to them).

Have you tested how much current your setup draws from the batteries?

Doesn't Eagle have an 'Export schematic as PDF or
JPG' function ?

Eagle has File:Export:Image, saves as .png

Thank you for your feedback on providing my sketches in a better way. I am new to the platform, so your guidance really helps!
Attached below are the images in .png format and sensor information documents in .pdf format!

Arduino Gas Sensor PCB Schematic.png

Arduino Gas Sensor PCB Schematic.png

TGS2600.pdf (262 KB)

TGS2602.pdf (362 KB)

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