The ordinary LED digital clocks will not be emplayed with timekeeping function , here, its achieved for the whole hour . Integrated circuits used in a programmable mute function itself , from 11 pm to 5 am is will not affect normal sleep . Circuit as shown. The whole point timekeeping control LED digital clock signal from circuit 3450 or 8560 of the pin is very common cathode display segment output bit b . Number from 0 to 4 , b section are for the high “1” only when the paragraph number 5 was to “0 . ”
So when the time from 59 minutes to carry the entire 00 minutes, can be picked up from the segment potential changes from 0 to 1 transition of the signal . The signal from the limiting resistor Rl , 4N25 optocoupler isolation coupling , transistor VT1 enlarged trigger control signal produced by C3 added to the Chinese language timekeeping integrated circuit ICl KD-482H trigger very , BL speaker sound can be sent timekeeping . Signal transmission using optical couplers to stroke does not affect the normal clock display.