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!

TK has combined a PIR with an Arduino to create a smart safety light for the house or workshop. Follow along as this gets built out into a more extensive project.

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.

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.