This tutorial will show you how to hack a common security motion sensor to turn an outlet on and off. You could hook up the arduino to the outlet and have it do things once the outlet is switched on. This could also be used to make a pretty good scarecrow for a garden.
This project deals with 120 volts which can be deadly, so be careful.
Motion sensor ($24 U.S.)
Outlet and outlet box($5 U.S.)
Extension Cord ($5 - $10)
This is the replacement motion sensor, available at a Lowe's hardware store.
A picture of it online: http://www.lowes.com/pd_247582-85538-SH-5316-BZ_4294857027+4294882837+5003700+5003720_42949370
There are three wires on the motion sensor:
Red- This one becomes hot once the detector senses motion. The sensor allows you to set it to come on for 1,5, or 20 minutes. It sends out 120 v so don't plug it into your arduino's pins.
If you cut open one end of an extension cord you will see three wires:
Black- Hot (power)
Make sure you don't plug this thing in while you're handling it.
The way it works is you connect the Black extension cord wire to the black sensor wire. Then, if you want to turn something on with the motion sensor you would connect it between the Red sensor wire and the Ground wires.
I have connected the red and three ground wires to an outlet. You just stick the wires into the sides of the outlet and screw it tight. Look at the outlet directions to make sure you put the power and ground on the right sides.
white sensor wire---- ( )
Green ground wire--- (OUTLET) - Red Hot sensor wire
White ground wire--- ( )
I fed the wires through the blue box first so that everything would be covered. I also tied a knot in the extension cord so that the cord wouldn't jerk out if it was pulled hard.
For some reason I wasn't able to get a multimeter reading between the red and ground until I actually connected it to some load like a light.
Supposedly the sensor can react to up to 100 ft away (30 meters), but 70 ft is probably more realistic.
There is actually a light sensor built into this particular product, so you can set it to only come on at night.
If you want to scare animals away plug in a blender. You could plug in a lamp in the living room for home use. It might be good for some Halloween projects as well.