Precision solid state string motion transducer for musical instruments with non-ferromagnetic strings, and method for precision measurements of time-variable position using 3-pole permanent magnets

摘要

A single axis position transducer uses an elongate permanent three pole magnet having a radial magnetic field at a spot along the magnet in which the magnetic field has radial field lines that decay as 1/R. R is the distance from the center of the magnet along a radial field line perpendicular to the axis of the magnet. The spot has a first pole of one polarity, and the magnet has poles of the opposite polarity spaced along the magnet on opposite sides of the first pole of the radial magnetic field located at the spot. At least one magnetic field sensor is positioned proximal to the spot along the elongate member that detects the motion of the spot and electrically amplifies the sensor output.