US Patent 6844713 Compact stud finder

A pocket-sized object finder has a compact housing containing a battery, circuitry and a capacitor plate for detecting an object hidden behind a wall. The battery powered circuitry includes multiple signal indicators that illuminate in a serial manner when the object is being detected. The signal indicators are successively tapered and are mounted at a front side of a tapered end of the housing. The capacitor plate is disposed in the housing along its rear wall and is responsive to variations in capacitance that occur as the object finder is brought near and over the object. The compact housing defines a cavity with a width that is no more than two inches and one third its length. A removable access door, with a pocket clip, at an end opposite the signal indicators allows access to the battery within the housing cavity.