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 simple photometer uses a 1 mA milliammeter and a common phototransistor. The circuit has its...
The circuit of the figure allows to implement a multimeter of high sensitivity or even to use a...
This simple circuit must be powered by a voltage of 5 V. The integrated circuit is the 7400, but...