Abstract: A device for determining a position by locating a point on one side of a barrier such as a wall from the other side of the barrier has two main parts, a magnetic field generator (sending unit) and a receiver (receiving unit) which is able to detect the magnetic field. The sending unit, which is placed on the first side of the wall at the spot to be located, creates a magnetic field at that spot. The receiving unit is composed of two pairs of detectors (four detectors total) which measure the relative strength of the magnetic field at each detector. Measurement of the relative strength of the magnetic field at each detector allows the position of the source to be determined. The strength of the field is indicated by the display of light emitting diodes. When the strength of the field is equal at all four points the receiving unit is centered directly on the opposite side of the wall from the sending unit.