PID controller for oven

Originally I was planning to build a PID-controlled toaster oven for solder reflow. I bought all the parts.

Then others at Xerocraft pointed out that they've had perfectly fine results doing toaster oven solder reflow by hand, without PID control.

So I put the project on hold until another application came up.

This afternoon the "killer app" arrived, when I measured the temperature in the 1960s oven in our apartment. When I set it to 400F, it went up to at least 622F before settling down to somewhere around 464F but still fluctuating quite a bit. That latter error is around 15 percent. The initial overshoot is >50%.

I figure I can do better and that the PID controller may be useful for other projects as well.

I guess it'll come in handy that one of the solid state relays I bought was overkill at 25A.

A spreadsheet I wrote up some months ago, when I bought the materials, is here, and it also links to some of the toaster oven PID controller project writeups I liked best.