From the maker of Power Radio – a professional radio application with RDS support for Windows Mobile devices – comes a new application especially designed for the HTC HD2 that takes advantage of the device’s built in compass.
The application is a proof of concept Metal Detector that works, according to the maker, the following way: “the built-in compass uses the earth’s magnetic field to calculate the deviation from magnetic north. As with every compass, if you put a piece of metal nearby, it gets distorted. Thats what i use here to detect metal”.
As for testing, the author says: “place your device flat on a surface. After starting the app, the gauge should show zero. If it doesnt, take your device and write a couple of “eights” in the air (this is to get rid of magnetism which might get stuck in the sensors).
Then use a pair of scissor or something the like and move it slowly to the right side of your device. At a distance of approx. 5 cm. the gauge should start to move. Take your device and move it with its right side near metals, and see if the gauge shows values”.
(Source: XDA Developers)