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!

For his sensor, [Felix] is using a Moteino, a very tiny Arduino compatible board with solder pads for an RFM12B and RFM69 radio transceivers. These very inexpensive radios – about $4 each ...

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

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 ...