Control button switches SB1-SB4 can be installed in different positions corridor, just move SB1 ~ SB4 any one button, lights EL horse lights on, and after decompression transfo
rmer, rectifier, to supply the integrated circuit 555. 555 integrated circuits, feet have connected 220yF initial capacitor voltage is zero, in an integrated circuit 555 is the first feet high output, relay K puff actuated, the normally open contact K is closed, the entire circuit into the timing of the self-locking status. Since then the power of the first integrated circuit 555, feet charge the capacitor voltage rises. When the electric charge container about 2/3 of the DC supply voltage to the timing between, about 3min. In this case 555 integrated circuits pin output toggles low, so K release, contact switch K automatically disconnected, lamp EL off. Just then press SB1-SB4 any of a button, the forks will re-timing lights turned on.