Dan Stahlke has built this AVR Based Power Usage Logger which uses an SD card to store the power usage data. It is similar to the DIY Power Consumption Monitoring System we saw last week. After seeing some of the charts I really want one, Dan shows where you can see the hot water tank cycling on and off and a bunch of laundry loads. I think once you see what impacts your energy usage some bad habits like leaving the fridge open too long may change. Dan provides all of the schematics so you can make your own.

Via: Embedds

“The current is measured using a pair of current transformers installed in the fusebox. The transformers are made from old TV flyback cores with 100 turns of magnet wire. A 0.2 ohm current sense resistor is connected to the coil and the whole thing is wrapped in electrical tape for safety. USB cables connect the sensors to the main unit, although shielded audio cables would work just as well.”