The digital clock circuit that electronic amateurs are most interested. And The clock ICs that most popular are LM8361, MM5387, Unfortunately these ICs looking for will be difficult.
I highly recommend this clock circuits features to work for less than the original circuits. But there are advantages due to have output in Duplex LED display model, so reduce the number of wires between IC1 (LM8560) and LED display was 2 times more than the original.
Note: Also this projects we can use Jumbo digital clock using simple CMOS ICs
How it works
In this circuits, the heart of the circuits are IC1 (LM8560), Which has output the 3 way are:
1. The output for drive display Duplex Model numbers (pin 1-14)
2. The output provide alarm signal at pin 16.
3. The output to control electrical appliances with automatic timer.
Two R1, C1 together with was integrating circuit to Provide input to the clock signal 50 Hz input lock pin (pin 25) of IC1.
Two diode D1, D2 are the switch signal generators to the cathode of display number for working alternately and relation with the input of IC1. The alarm signal from pin 16 of IC1, will be entered to the potentiometer P1(Volume), to pin 3 of IC2 (LM386), that is alarm signal amplifiers to drive the loudspeaker.
The P1 so is fine a alarm sound pressure as you want. And the sleep out signal from pin 17 that you can continue to use, to control another circuits.
how to set the time
1. Press the switch S6 to set hours.
2. Press the switch S4 to set minutes.
To set the alarm time
1. Press the switch S3 to hold down.
2. Press the switch S5 to set hours.
3. Press the switch S4 to set minutes.
When the time limit, the alarm signal will ring. Press switch S2 or other switches to stop the alarm sound.
– Cancel the alarm system, press S2 to hold down.
To set the time turn on- off the Electric appliance.
1. Press switch S6
2. Press switch S4 to set minutes, Time to show the remaining time.
3. Press switch S5 to set hours.
Time dilation alarm to repeat alarm.
In the case of alarm circuit operation and we want to Repeat alarm. To extended for another nine minutes, with the press of a switch S7. The output signal for control turn on-off electric appliance circuit, get from pin 17 of IC1.
Detail of parts
IC1__________________________________LM8560B DIGITAL ALARM CLOCK
D1, D2, D3___________________________1N4001 50V 1A Diodes
R1__________________________________100K 1/4w resistor
R2, R3_______________________________120ohm 1/4w resistor
R4___________________________________91K 1/4w resistor
R5___________________________________10ohm 1/4w resistor
Volume P1____________________________10K Potentiometer
C1, C5_______________________________0.01uF 50V Polyester Capacitor
C2__________________________________470uF 16V Electrolytic Capacitors
C3, C4_______________________________0.1uF 50V Polyester Capacitor
C6__________________________________10uF 16V Electrolytic Capacitors
C7__________________________________100uF 16V Electrolytic Capacitors
How to build.
-You place the electronic components on the PCB board correctly completed, as shown in the picture, The display numbers can use bent wire to perpendicular. Then soldered directly to the PCB and LED display.
Note: PCB layout print in 300 dot per inch
-These switches you are able to put directly on PCB.
-You can choose display is 12 hours with open pin 28.
– If you want to connect a battery backup to the circuits continues to operate, even when the power goes out. You just connect the 9 volt battery, by the negative terminal join to diode 1N4001 into pin 20 of IC1 and the positive terminal at pin 28.
-To work range power clock cycle will continue. But it will not display on the screen.
-If do not has the backup power supply when the power goes out then restart display circuit will blink.
We recommend these below
LM8365 alarm digital clock for beginners
Jumbo digital clock using simple CMOS ICs
Time based clock generator using crystal for digital
The 60hz calibration frequency standards for digital clock by MM5369