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!

A PIR sensor on the front of the can detects when somebody gets close, and plays a message reminding them to make use of the trash cans provided on the playground.

While PIR sensors can be used with Arduino and other microcontroller boards, those best-suited for hobby use are smart enough to perform simple tasks without any programming.

Present consists of just a PIR sensor and Arduino in a 3D printed enclosure to snap onto your monitor.

Using motion detectors and an Arduino you can trigger lights, fans, or even an pneumatically controlled cleaver-wielding clown to help add your house to the “if you dare” list.

PIR sensors (PIRs) use heat radiation from bodies to identify the presence of people and animals. This can be used for unlocking doors or starting a video recording.