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!

We’re still not sure exactly how [connornishijima]’s motion detector works, though many readers offered plausible explanations in the comments the last time we covered it. It works well… ...

What he came up with is a light-sensitive motion sensor that uses very little power. He knew that an Arduino would be overkill, and decided to try his hand at using the Arduino to develop code for ...

Makers and developers looking for a motion sensor Arduino Shield, are sure to be interested in this new ICU-Duino which has been created by Patrick Thomas Mitchell based in Ottawa, Canada.

Make sure the adjustment knobs for sensitivity and on-time for the motion sensor are facing up so you can modify how sensitive your device is and how long it stays on to signal your Arduino.

The motion sensor switch circuit can automatically turn on a water sprinkler but you can easily use it as a motion sensor light switch or motion activated alarm too.

The system here uses a cheap Arduino board, a few sensors, and a magnetic contact switch. It’s then hooked into the Adafruit IO and connected to IFTTT, so you can set up alerts in any way you like.