Contactless electrical thermostat employing a bimetallic strip

摘要

A thermostat employing a bimetallic strip carrying a permanent magnet and a saturable magnetic core positioned at an adjacent fixed location is disclosed. The magnetic core has a primary winding that is supplied with electrical pulses and a secondary winding which is coupled to an output circuit, preferably including a Schmitt trigger circuit. When the bimetallic strip is bent due to the environmental temperature so that the permanent magnet is closely magnetically coupled to the magnetic core, the core approaches saturation and the pulse output signal decreases in magnitude. The output circuit is constructed to have electrical hysteresis so that the "turn on" and "turn off" levels of the circuit are different.