A battery-powered infrared thermometer with a laser pointer built with an ESP8266 microcontroller and an MLX90614 sensor.

• Measures ambient and target object temperature with the MLX90614 infrared sensor.
  • -40 … +125 °C for sensor temperature
  • -70 … +380 °C for object temperature
  • High accuracy of 0.5 °C over wide temperature range (0 … +50 °C for both Ta and To)
  • High (medical) accuracy calibration
  • Measurement resolution of 0.02 °C
• Shoots a laser beam to mark the target object.
• Powered by a 18650 battery (Model A) or a LiFePO4 3.2V AA battery (Model D).
• Measures battery level.
• Displays measured data on the Wemos OLED shield.
• Controlled by a Wemos D1 Mini microcontroller board.
• Allows charging the battery via a TP4056 charger (Model A).

The used microcontroller board has built-in WiFi capability, therefore it is possible to transmit the measured values over the wireless network for further processing (this feature is not implemented).

• Features
• On this page
• Getting Started
  • Hardware
    • Bill of Materials
    • Wiring
  • Software
    • Prerequisites
    • Setup
  • 3D-Printed Case
• About the author

(This Table of Contents was generated with nGitHubTOC, but sompylasar's solution is also very usable.)

You need the following hardware components to build this project:

• Wemos D1 Mini controller board
• Wemos OLED shield
• MLX90614 infrared sensor
• 5V laser pointer
• 220K resistor (to measure the battery level)
• On-off switch
• Momentary push button
• For Model A:
  • 18650 battery
  • 18650 battery holder
  • TP4056 battery charger board
• For Model D:
  • LiFePO4 3.2V AA battery
  • Single AA battery holder
  • M3x6 screw to mount the battery holder

Model A:

Model D:

You can find the Fritzing file in the ./hardware folder.

Install the following libraries in the Arduino IDE:

• Adafruit GFX Library by Adafruit.
• Adafruit SSD1306 Wemos Mini OLED by Adafruit + mcauser
• Adafruit MLX90614 by Adafruit.

Just compile and upload the ./software/InfraredThermometer/InfraredThermometer.ino file from this repository and you are done! No additional configuration is necessary.

I designed a 3D printable case only for Model D. It's more a part-holder bone than a full housing, but still it is functional and I find it cool that it reveals how the device is working.

You can find the 3D printable STL and all the source files in the ./case folder.

You can print with 0.2mm layer height without support. The holes for the buttons and the battery holder mounting screw is covered with a sacrificial layer to avoid supports, so you must remove that after printing.

Shares on 3D printing community sites for comments and remixes:

• Thingiverse: https://www.thingiverse.com/thing:4222541
• PrusaPrinters: https://www.prusaprinters.org/prints/25513-infrared-thermometer-aka-laser-temp-gun

This project is maintained by György Balássy.