This shield circuit is from a 1968s Motorola documentation. The relay is according to the supply voltage. R1 can be reduced to lower trigger voltages.
This circuit uses a common diode as sensor. The output goes from 0 to 10 V with the temperature change in...
The circuit presented was suggested by the National Semiconductor's Linear Applications Handbook of...
This circuit was found in a 1966’s NASA documentation. The circuit shows how to use thermistors...