Here is a simple general-purpose security alarm circuit built on the Arduino platform. It brings up an obtrusive alert signal when an intrusion/theft attempt is observed by its front-end sensor. In ...

Here is an ultra simple Arduino Night Alarm project wired around a handful of inexpensive and easily available components. One advantage of using Arduino as a security system is the flexibility!

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.

By using open-source Arduino tools, security researchers are exposing security gaps in door-lock systems used by millions of hotels.

Making your own security system isn't too hard, but if you'd like a super cheap and simple method, Instructables user deba168 shows how to make a wireless motion detector with an Arduino.

Many people would be tempted to write a really simple script that would just open the door and connect without any real thought about security. After all, this is a one-off obscure garage door opener.

You'll need an Arduino along with a bunch of various sensors to get the project rolling, and once it's all set up you'll have a simple, but cheap system to monitor your home.