Temperature switch circuit 2

It can be used as an automatic constant temperature control for food refrigeration boxes, keeping the temperature inside the box at
-8~-10°C.
    The temperature measuring element uses a thermistor R with a negative temperature coefficient. . The measuring bridge is composed of resistors Ri, R2, R3 and wind. When
the temperature inside the box is higher than -8℃, the relay KA is released, the contactor KM is closed, and the refrigerator works. When the temperature inside the box drops to
-10°C, KA closes, KM releases, and the refrigerator stops cooling. When the temperature inside the box rises to -8°C again, the circuit automatically
flips over and repeats the above process, thereby keeping the temperature inside the box between -8 and -10°C.
    Negative temperature coefficient thermistor R. Choose RR03-2 type, the resistance value is 2.4kn at 25℃.