Toaster Oven Controller

Here are some photos of the printed circuit board (PCB) oven controller in operation at the Boulder Hackerspace. The oven controller regulates the temperature to a pre-defined curve (over time) that works well for solder paste and electronic components. It isn’t necessary for home-PCB construction since temperature regulation can often be done by eyesight. The catch is, building PCBs requires solder paste, and heating solder-paste by eyesight is prone to error, requires constant attention, and somewhat risky in the constant need to handle the oven.

Pictured is the Sparkfun Reflow Oven Controller running the firmware from Kit Ryan’s article, a 1350 watt toaster oven, and an EEPROM chip I used for the first test-run. This chip could have been soldered by hand (flux required) and the paste was dry but the oven still produced a nice breakout.

The oven controller improves safety. The exposed circuit in the photo (on the left) is a low-voltage circuit — all of the high power circuitry is fully insulated with the oven attached to a ground-fault outlet. The ground-fault protection is limited, but intended for extra protection in certain situations. Soon, I’ll design a case in Sketchup for the controller and we’ll print a copy on the 3D printer at SSD. The only other thing to tighten-up on the build is the thermocouple attachment. Maybe I’ll drill a hole in the oven and install a metal terminal/clamp for the thermocouple if I come across the proper connector. For now it’s just threaded through some vents in the side of the oven. The hack seems to work OK.

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