The thermostat is made based on the principle of thermal expansion and contraction of objects. Thermal expansion and contraction are common properties of objects, but the degree of thermal expansion and contraction of different objects is different. The two sides of the double gold sheet are conductors of different materials. Under changing temperatures, the double gold sheet bends due to different expansion and contraction degrees, and touches the set contact or switch, so that the set circuit (protection) starts to work.
This is the basic working principle and production idea of the thermostat.