This circuit diagram shows an automatic LED emergency light that uses a white LED to provide bright light when main power fails. A battery is charged by an automatic charger circuit that stops when the battery is fully charged. An LM317 IC regulates 7V to charge the battery. A BD140 transistor drives the output while a BC548 transistor and zener diode control battery charging. It is recommended to connect a heat sink to the BD140 transistor and adjust the LM317 potentiometer to set the output to 7V before use.
