It works! So leaded or unleaded solder is currently set by changing a variable to &apos;leaded&apos; or &apos;unleaded&apos;, then re-uploading the software. Next step is making the pushbutton set the temp profile. There&apos;s no PID involved, this program just repeatedly checks the temp and turns the coil on or off, which seems adequate for this application. I&apos;ve never seen it overshoot by more than 2 degrees C. K-type thermocouple is held to the toaster by Kapton tape, which has shown no difficulty at the temperatures involved (max 218C for lead-free solder). Engineering notes are here: <a href="https://sites.google.com/site/reflowoaster/home" target="_blank">https://sites.google.com/site/reflowoaster/home</a>