A magnetostrictive displacement sensor measures linear position using the interaction between a current pulse and a permanent magnet. Its core is a magnetostrictive waveguide, usually a thin alloy wire or tube. A movable position magnet is placed along the waveguide. The sensor electronics send a short current pulse down the waveguide at a stable speed. This pulse creates a circular magnetic field around the wire. At the magnet's position, the permanent magnetic field interacts with the current pulse field. Due to the magnetostrictive effect, also called the Wiedemann effect, this interaction generates a small torsional strain wave in the waveguide. The strain wave travels back to the sensor head at a known ultrasonic speed. A pickup coil or detector converts this mechanical pulse into an electrical signal. The time between launching the current pulse and detecting the returned strain wave is directly proportional to the distance from the sensor head to the position magnet. By measuring this time accurately, the electronics calculate absolute displacement. Because the magnet does not touch the waveguide, wear is low and reliability is high. A damping module absorbs the wave to prevent reflections. Temperature compensation and precise timing circuits improve stability. These sensors offer high resolution, repeatability, and absolute position without re-zeroing after power loss. They are widely used in hydraulic cylinders, injection molding machines, steel mills, and automation for real-time linear feedback.