Balance temperature switch

Usually we have seen in this type of equipment, consisting of thermistor or temperature sensor in variations. Around this time, found sensor which will that is new it that new, will be old it is old, Actually, because is known, and then some, I will explain it to someone who knows only
Temperature sensor with a semiconductor devices.
-It is actually, all the semiconductor resistance within. Which decreased when heated, will be very or least it is up to the agents used in the doping process. This includes a semiconductor, resistor, integrated circuit, transistor, etc..
-A diode is a semiconductor device at inexpensive, as compared to other devices, then select is temperature sensor in this circuit.

Dfferential Temperature Relay Switch by IC 741 
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