Turning a Toaster Oven into a Reflow Oven — A Safety Design Story

A hobbyist converts an Iris Ohyama toaster oven into a DIY reflow oven and focuses on safety architecture.

The design rejects a fuse as protection for an SSR stuck on, since it would not reliably stop heater runaway.

Instead, it layers software temperature shutdown, sensor-fault detection, and watchdog reset on an ESP32 controller.

A separate KSD9700 thermostat provides an independent AC cutoff as the final hardware safeguard.

The article also stresses wired-OR safety logic so any fault can turn the heater off.