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!

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.

The PIR module actually consists of a pyroelectric sensor (looks like an old metal transistor with a black window on the top), which generates energy when exposed to heat, and it’s tied in closely ...

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

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.