Inexpensive water-level detector for washing machine tub - comprising electronic device detecting various levels

摘要

A static detector replaces the pivoting arm of a bistable contacter, and consists of a pressure detector with a membrane balanced by a spring, to give a practically linear push-pull action. A soft ferrite core, coaxial to the membrane, moves with it, and a fixed coil is coaxial with the core. The coil is in parallel with a capacitor forming an oscillating circuit incorporated in an electronic circuit maintaining its oscillation. The frequency of oscillation varies according to the position of the core, and the data processed reflects directly the different water levels.