Energy Meter

Measure the total household electricity consumption.

Most electical meters today have a diode that transmits pulses in step with consumption. The diode is marked like "1000 imp / kWh". Put the phone's camera to the diode and measure consumption. The diode probably transmits in infrared so it will not be visible to human eyes, however the camera on the phone will see it.

More instructions on google+ site

https://plus.google.com/u/0/b/108719271699520743932/