[mircemk] shows how to create a simple non-contact proximity sensor using little more than an Arduino Nano board, and a convenient software library intended to measure the value of capacitors. The … ...

Professionally-installed security systems can be expensive and require contracts; instead, we examine some of the growing number of low-cost DIY alternatives.

[Jeff Sandberg] demonstrates that ably with his project to use ancient 1990s burglar alarm sensors in his modern smarthome setup. The sensors in question are from an old GM Interlogix security system.