WiFi enabled (ESP8266) thermocouple (MAX31855) (for Raku ovens or anything else). Draws around 60mA so it can easily be powered from a cheap usb power bank for the duration of a Raku burn.

Uses the CaptivePortalAdvanced and httpUpdater example that comes with the Arduino core for the ESP8266 for handling WiFi and OTA firmware updates. Websockets and Chart.js is used to display a live graph of the temperature read from a K-type thermocouple (-200 to 1350 degrees celsius) with the Adafruit MAX31855 library.

Mobile screenshot, one graph for the last 68 minutes and one for the last 17 hours:

• WeMos D1 mini: https://www.aliexpress.com/item/D1-mini-V2-Mini-NodeMcu-4M-bytes-Lua-WIFI-Internet-of-Things-development-board-based-ESP8266/32681374223.html
• MAX31855 breakout: https://www.aliexpress.com/item/Hot-Sale-High-Quality-MAX31855-K-Type-Thermocouple-Breakout-Board-Temperature-1350-Celsius-for-3V-5V/32647767866.html
• K-type thermocouple: https://www.aliexpress.com/item/Newest-Style-Best-Price-High-Temperature-100-To-1250-Degree-Thermocouple-K-Type-100mm-Stainless-Steel/32635321141.html
• Enslosure: https://www.aliexpress.com/item/J34-Free-Shipping-Waterproof-Plastic-Electronic-Project-Box-Case-Enclosure-2-56-L-x-2-28/32579201101.html
• Some wires & hot glue :)

Hardware before screwing on the lid and "sealing" with hot glue. Black tape on WeMos and MAX31855 breakout to prevent shorting anything on the PCB:s