摘要 |
PURPOSE:To light a lamp automatically only when the electric power of a commercial power supply AC is stopped in the night. CONSTITUTION:A lamp L is connected to a battery B through a relay RY and a changeover circuit 11 composed of the normally closed contacts RYb, RTb of a flasher unit TR, and the battery B trickle-charges at all times by a commercial power supply AC through a transformer T, a rectifier RF, a resistor R1 and a fuse F. The flasher unit RT closes the normally closed contact RTb in the night, and the relay RY is returned when the commercial power supply AC is lost, thus lighting the lamp L according to the specified conditions of lighting. |