The integrated circuits used in this thermometer are not very common today. The indicator is a microammeter for a scale from 0 to 100o C. The supply must be made with a voltage of 1 to 12 V.
The circuit shown is from an old European publication. In it we have the way to activate a relay...
We found this circuit in a European publication from the 1990s. Transistors are still common types...
This circuit was found in an American documentation and can be added to common amplifiers of any...