This simple Door Chime protects the door and gives a loud Alarm tone when there is an attempt of theft. The circuit is too simple and battery operated. A Normally Closed (NC) reed switch and magnet is ...

I was flipping through my deadtree archive of magazines recently when I came across an ad for an ingenious little door alarm in 1906. Granted, it’s not fancy. But it probably did the trick. As you can ...

Now you can build your own simple door alarm security system using a tiny microcontroller chip PIC12F635! The circuit is nothing but an aural alert unit, which raises ...