He’s using an Arduino Uno and an Ethernet breakout board to hook it up to the network. This allows him to send text messages to himself when the alarm system is armed, disarmed, or triggered.

[over9k] used his Arduino to set up a laser trip wire. The laser is mounted along side the Arduino, reflects off of a mirror, and shines on a photoresistor that interfaces via a voltage divider.

Sure, it might look like an overly complex system on screen ... Powered by an Arduino Uno, this laser tripwire alarm project works much like those in movies. There's a tripwire — made up ...