I'm working on an idea where I need to measure temperatures to around 500°C - above those typically supported with semiconductor sensors or thermistors.

This project demonstrates the basic approach using an Arduino as the "temperature logger". I'm using a K Type thermocouple that's rated up to 700°C. Since thermocouples only measure a differential temperature, I'm also using an LM35 to provide the cold-junction baseline. The temperature measurement is displayed on a 5110 LCD.

As always, all notes, schematics and code are in the Little Electronics & Arduino Projects repo on GitHub.