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.
This small unregulated variable power supply was found in an American book from the 60's. The...
This circuit indicates when the voltage of a 12 V battery is low. With changes, for example, the...
This basic circuit is from 1984 documentation. This circuit can be used as an efficient burglar alarm...