Detecting motion with an Arduino and two wires

Connor Nishijima has come with a unique way to detect motion using an Arduino Uno. The active media developer is polling an ADC pin with a pair of wires twisted tightly together — one plugged into A3, another plugged into ground — and generating readings whenever a large living object (like his two cats) is nearby.

“The closest I have ever come to explaining this is capacitive coupling. So what it is is the antenna is leaching a little bit of electricity off you, and you are leaching a little bit of electricity from the antenna. The differential that happens when you move around is what the Arduino is picking up.”

He’s calling this effect “Capacitive Turbulence,” and so far he’s only got it work on the Arduino, no luck using other boards with ADCs. You can watch him explain this magical phenomenon in more detail below!

from Arduino Blog http://bit.ly/1TUZaNZ