The above circuit is a proven device that is capable of detecting small to large disturbances in the electromagnetic field around it. When adjusted properly it can signal when large metal vehicles come near it or airplanes fly over it.

At the heart of this design is the 1490 digital compass and the 16F84A microcontroller.

You could hunt down each part and build the thing yourself with the above schematic which is generously given for free along with some detailed notes on the construction by the fascinating website that goes by the name of Imagesco.com.


If you're short on time Imagesco will sell you a kit with all the parts and instructions for 65 bucks. If building isn't your thing you can spring for their fully assembled unit for 95.




I think this circuit is a good place for the home builder to start from. Maybe someone out there will figure out a way to adapt it to a cell phone so one could have multiple sensor stations postioned to form a circle around your house or trailer. Once the unit was triggered it could call your home computer to report a disturbance. If a person was equipped he or she could have several such stations scattered around the globe or county depending on your level of curiosity.

Image credit goes to ufopictureblog.com for the cool flying saucer diagram.