[Michael] got his hands on a refrigerator that he intended to store beer in but found that it ran constantly. Instead of buying a new thermostat he and his friend [Doug] set out to build an Arduino-based controller for the fridge.
The finished project will switch 240v so they’ve used a transformer to power the logic circuitry and a solid state relay to handle the load switching, with a Dallas 1820 for temperature data. Because the Arduino offers more capabilities than the average thermostat hack they also decided to tap into its potential by adding an Ethernet shield. We see the Arduino as a prototyping device and so do these folks. Once the bugs in their first PCB prototype are worked out the circuit will use the ATmega328 and do away with the Arduino.