[3ricj] wrote up how to build your own low temperature test chamber to verify that electronics will function at the edge of the atmosphere/outerspace. He needs this for the edge of space project he’s working on. A large cooler serves as the test chamber. It’s cooled down to about
0c -42C with dry ice, then a supply of liquid nitrogen is fed into a copper heat exchanging coil to bring the chamber down to -70C.