This is a Big digital clock circuit without microcontroller for large size: 6 CM, cause can see clear on Very clearly in the range of 10 meters, even in the dark, because the display is easy to read numbers.
This projects use all CMOS ICs that easy to buy in store than the Cheap Digital time clock with alarm circuit by LM8560
The working principle
Look at Figure 1 is block diagram main principle of this projects. To begin with an 50Hz signal from AC line at our home, then it will be convert waveform from sinewave to digital signal in square of 50 Hz, then to feeds a 3000 counter circuit (with divided frequency inside).
Which this frequency 50 Hz, for 1 second will have the 50 cycle, so when we can count of 3000 cycle to must the times for 60 second. Which equals 1 minute digits there.
Therefore, when the 3000 counter circuit counts wave of 3000 cycle (1 minute). Then it will send the signal to a sixty counter circuit to add the numbers in the minutes digits of the clock in one step.
Next recounts in 3000 cycle. Then send to the sixty counter in new continuously until to 59 digits, then will reverse into 0 number new.
In this time period will send signal to the thirteen counter add next step one and upto 12 digits, then will back to 0 number new then continues.
On base of principle we come to see real circuit in Figure 2 Diode (D1-D4), Capacitors(C1), Resistor (R2) and Zener diode (ZD1) acts as convert AC 12 volts is DC and The ability to maintain the regulated supply. The resistors R1,R3 and C2,IC1/1 are convert circuit to IC2.
Which worked together with IC3 is the 3000 counter circuit. And divide frequency at pin 2 of IC2 will connected to base of transistor Q1, cause LED1-4 flash with frequency of 0.78 Hz
IC4, IC1/3, IC1/4 work together with the sixty counter circuit , next IC7, IC9/1, IC9/2, IC9/3 and Diode D5 work with into the 13 counter circuit.
Q2 acts as driver to LED119-LED128 display minute digits of hours( since 10,11 and 12 hour)
– Then IC5, IC6 and IC8 will decode on minute and hour digits to display clock number. Which use LED5-LED118.
– For each of the digit have Structure to be used as Figure 2. Which are seen as the LED on the main number to 38 pcs. Make large numbers more beautiful.
Idea to builds
This project is very detailed. I recommend just creating a concept only.
Note: Because this project We have not created their own If you are interested in building this project. Require careful enough.
IC1___________CD4093_______= 1 pcs.
IC2___________CD4040_______= 1 pcs.
IC3___________CD4068_______= 1 pcs.
IC4,IC7________CD4518_______= 2 pcs.
IC5,IC6,IC8____CD4511________= 3 pcs.
Q1,Q2______BC549__transistors___________= 2 pcs.
D1-D4______1N4003__Diodes_____________= 4 pcs.
D5_________1N914__Diodes______________= 1 pcs.
ZD1_______12V 500mW___Zener_Diode____= 1 pcs.
C3,C4______300pF 50V Ceramic capacitors_= 2 pcs.
C2_________0.0047uF 50V “_________”___= 1 pcs.
C1_________1000uF 25V__Electrolytic capacitors = 1 pcs.
LED1-LED128___LED: red rectangle form = 128 pcs.
Resistors 0.25W 5%
R1,R6,R21,R22_______10K____________________ = 4 pcs.
R2_________________470 ohms_______________ = 1 pcs.
R3_________________470K___________________ = 1 pcs.
R4_________________330 ohms_______________ = 1 pcs.
R5,R32_____________100K____________________ = 2 pcs.
R7,R10,R13,R14,R17,R20,R23,R26,R29___150 ohms = 9 pcs.
R8,R9,R11,R12,R15,R16,R18,R24,R25,R27,R28__180 ohms = 12 pcs.
S1,S2___Normally Open Pushbutton Switch
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