Rotary Position Sensor

A low-cost rotary position sensor that uses capacitive coupling between copper planes to measure absolute rotation. The design uses time-domain measurement: transmit (TX) pads charge and discharge, inducing transient signals on receive (RX) pads, whose magnitude encodes the geometric relationship between plates and thus the rotation angle. Hardware consists of laser-cut wood, copper tape, a custom PCB, and a thrust bearing acting as a slip ring. Two RX pads are used — a larger one for rotation magnitude and a smaller one to resolve clockwise vs. counterclockwise ambiguity.