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.
This 1975 circuit for automotive applications replaces the mechanical vibrator found in old cars...
This is the name given to this small MW transmitter that can function as a wireless microphone. The...
This oscillator uses a ceramic resonator to determine the frequency. This kind of element is found...