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!

Once you get the alarm set up, it’ll sense movement near the Arduino, snap a picture, then send it over to you using If This Then That. All you’ll need is an Arduino Yún, PIR sensor, a USB ...

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.

It’s a simple little hack, but [Lochie] is pleased with it, and we imagine that he likely has a long list of other creative ideas in mind for his newly discovered PIR sensor.

With just a Wemos D1 Mini, a standard PIR sensor, and some open source code, you can create a practical self-contained motion sensor module that can be placed anywhere you want to keep an eye on.

It combines an Arduino-compatible processor with a light sensor, a temperature sensor, a 3-axis accelerometer, a joystick, a set of pushbuttons, a slider, an RGB LED, and a buzzer.