Remember the laser based alarm system that you see in spy movies? The one that sets the alarm when the laser gets cut by any object? Guess what, – you can have one at home! And what’s more? You can make one using an arduino!
This project was featured in instructibles.com, it’s a fairly simple approach in building a laser based security system – and don’t get me wrong the laser is visible unlike the ones in mission impossible where they use infrared. A laser diode / pointer is biased using a resistor and a battery and a switch is place on series to have a way of turning it on and off. The other end of the system is made up of a photo resistor attached to an arduino. The laser is positioned so that the light hits the photo resistor and when some one cuts the light the change in the resistance in the photo resistor will be detected by the arduino and in turn it will fire the alarm – the good old buzzer! And the best part of this project? It comes in Altoids!