This circuit is from a 1968 documentation. It makes use of thermistors (NTC) to indicate overheating of charged batteries. Modern equivalent components can be used.
This touch switch appears elsewhere on this site from various documentation. This is from an 80's...
This circuit aims to recover batteries that are no longer fully charged due to the memory effect. We...
This circuit activates a machine to dry hands (fan and heater) when the sensor detects the...