Based on a 555, this 80's American documentation circuit detects the voltage of a battery and can then disconnect the charger. The transistor may be a general purpose type.
The battery charger suggested in the figure has its current limited by resistor R1. This component can...
The operation of this circuit is not common today, but equivalents can be experienced. The circuit is...
This circuit generates various types of sounds and can be used as a toy. The circuit is from Radio...