Arduino + Triac based PID controller for using a Hot Air Popcorn machine to roast coffee. Aims to be completely usable without a computer or any other tethered device while maintaining a simple, tactile and somewhat old-fashioned physical control panel interface. Currently supports PID constant temperature and constant power modes. Hope to expand with PID RoR (Rate of Rise) control, and much later, preset automatic roasting profiles.
Magi-Roast started with the kind donation of a well worn Magi-Pop hot air popcorn roaster to our household by @lerouxb. We had recently received some Cameroonian green beans as a gift and decided to use the Magi-Pop to roast them. It worked, but the roast was really fast and hard to control (around 3 minutes to second crack). At the same time I had recently built a TRIAC circuit for controlling an abandoned simulated-sunrise alarm-clock project. We had also recently aquired a 3D printer. It was Destiny.
Magi-Roast is now kind of a version 1.0: It roasts, it controls temperature, it controls power and has a basic interface. Apart from the home-built power control module it is a fairly standard Arduino + modules from Banggood build. In spite of that I do hope you'll find subsequent updates on how it got to 1.0 and future plans interesting.