Chamber: Sourdough Incubator

All you knead to know

Trent decided to take on the challenge of designing a product to meet his culinary needs, and was sure that he wanted to incorporate a small Peltier cooler in his project, as his friend Scott Hutchinson had given him the idea on a camping trip. “He happened to be a spacecraft thermal systems engineer and suggested using the Peltier cooler for both cooling and heating,” says Trent. “I thought this was so slick that I really got moving on the project when I got home.”

So, how exactly does the incubator work? “The Chamber utilises a Peltier cooler, also known as a thermoelectric cooler, to either pump heat from inside the Chamber to the outside (cooling the interior) or to pump heat from outside the Chamber to the inside (heating the interior),” explains Trent. “The direction that the heat is pumped is simply controlled by alternating the polarity of the voltage applied to the Peltier cooler.”

He changes the temperature in the Chamber with an H-bridge module driven by a Raspberry Pi Zero. So, if the temperature gets too high, the fan on the outside wall pushes the heat away, and if too cold, another inside fan pulls warm air in. This being Trent’s first Raspberry Pi project, he appears converted, saying the single-board computer “is just such a great tool for personal projects: there is an excellent community offering software libraries, lots of compatible hardware, and helpful guides.”

You say sour, I say sauer

It’s true that bakers can buy proofing boxes, but Trent thinks that his incubator has clear advantages over commercially available alternatives. “The big advantage my chamber offers is heating and cooling in one package; plus it might be cheaper. Some of the off-the-shelf, heat-only options are almost $200 new, while mine is ~$180.” In addition, Trent’s invention can be used for other foodstuffs: “I enjoy baking, and I really enjoy eating bread, but I’d be lying if I didn’t say that the mad scientist aspect of harnessing the power of fungi and bacteria to create tasty foods didn’t draw me in… we’ve also fermented jars of garlic and jalapeños, sauerkraut, and various peppers. I’m proud to report that everything has tasted good.”

Trent demonstrated his Chamber at the 2019 Hackaday Superconference, and got a brilliant response from like-minded makers. “Right at the start of my talk I said something like, ‘for those of you who maintain sourdough starters, you might be familiar with specific target temperatures but no means to control to those temperatures,’ and I noticed that a good number of people were smiling and nodding their heads. At that moment, I realised there were more people with this problem than I originally thought,” he says.