This circuit is a thermo Switch using a Thermocouple. It can switch ON/OFF a load when temperature rises above a certain value. Max. load current could be 10A.
You can order this PCB from here:
https://www.pcbway.com/project/shareproject/W158454ASS90_Gerber_Thermo_Switch.html
Parts list:
IC CA3140
12V Relay
Diode 1N4007
Diode 1N4148
Transistor 2N2222
LED
Resistor 1K (2pcs)
Resistor 100K
Resistor 10K
Multiturn Potentiometer 500 ohm
Thermocouple K-Type
Terminal connectors 2p and 3p
Banana Socket
IC Socket 8 pin
Circuit Diagram:
Thermocouple polarity is so important !
Video:
