DIY AC amp sensor for Tweet-a-Watt
Ok, this might not be some blinky and spectacular thing but it is a very good starting point for something that might become pretty serious.
We all know what Tweet-a-Watt is. It is a device based on a Kill-a-Watt device that you can buy in your local store and it measures current consumption up to 15A (1.8kW). The problem with this thing is that it uses shunt resistor inside to measure the current, so the current that can pass through that shunt is limited. Now, if only we could measure the current through the load's wire without redirecting it through a device, than the measured current would practically be unlimited... well, we can! By using some wire and a C-clamp we can make a clamp-on ampere meter. Next thing would be to configure the ZigBee module to read this induced AC mV value and we have our own Tweet-a-Watt!