LED digital clock language timekeeping circuit

Posted on Nov 10, 2015

General Dynamic LED digital clock have no timekeeping function, just add here a simple circuit it can bring the whole point timekeeping function.

LED digital clock language timekeeping circuit
Click here to download the full size of the above Circuit.

IC itself has used programmable mute function, from 23:00 to 5:00 is not of time, it will not affect normal sleep. Circuit is shown. The whole point timekeeping control signal from the LED digital clock IC 3450 or 8560 feet, the foot is a very common cathode display bit b segment output. Numbers 0 to 4:00, b segment are high level "1" only in the number 5 that paragraph was to "0." So that when the time from 59 minutes to carry the whole point of 00 minutes, from the potential of the segment can be picked up by a 0 to 1 transition of the signal. This signal by the current-limiting resistor Rl, 4N25 optocoupler isolation coupling, trigger control signal generating transistor VT1 amplified by C3 added ICl Chinese language repeater IC KD-482H trigger pole speaker BL issue can chime sound. Using optocouplers transmit signals in order not to affect the normal display clock stroke;

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