LED digital clock language time reporting circuit

Generally, dynamic LED digital clocks do not have the time-telling function. Here, we only need to add a simple circuit to make it realize the hourly time-telling function. The integrated circuit used has a programmable mute function. It will not tell time from 11 pm to 5 am, which will not affect normal sleep. The circuit is shown in the figure. The hourly time-telling control signal is taken from the ⑧ foot of the LED digital clock integrated circuit 3450 or 8560, which is the output end of the b segment of the tenth position of the common cathode display screen. When the numbers are 0 to 4, the b segment is a high level "1", and only when the number is 5, the segment is "0". In this way, when the time is carried from 59 minutes to 00 minutes on the hour, the jump signal of the potential changing from 0 to 1 can be picked up from this segment. This signal is limited by the resistor Rl, isolated and coupled by the photoelectric coupler 4N25, and amplified by the transistor VT1 to generate a trigger control signal, which is added to the trigger pole of the ICl Chinese language time-telling integrated circuit KD-482H through C3, and the speaker BL can emit a time-telling sound. The use of photoelectric couplers to transmit signals is to avoid affecting the normal display of the clock strokes;