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.
Found in a 90’s Popular Electronics, this circuit generates sinusoidal signals with frequency...
An interesting basic circuit for projects is the one shown in the figure which consists of a...
This power supply with a power inverter was found in a documentation on transistors from 1960. The...