A Magnetic Pickup Sensor (MPU sensor), also commonly called a Variable Reluctance Sensor (VRS), Magnetic Speed Sensor, or simply a Pickup Coil, is a fundamental and robust type of sensor used to detect the presence, speed, and sometimes position of ferrous (iron-containing) metal objects. How It Works (Simple Principle) It's based on Faraday's Law of Electromagnetic Induction. The core components are: 1. A Permanent Magnet: Creates a stationary magnetic field. 2. A Pole Piece: A soft iron core t