Introduction: LED Clock Using 555 and 4017 (No Programming Needed)

About: Hello My name is Ahmed Darwish. I’m 39 years old, married and have two wonderful children (Abdulrahman and Emma). I’m an Egyptian electronics and telecommunications engineer. I live and work in State of Kuwait…

Here I shall introduce a project I designed and made about 7 years ago.

The idea of the project is to use counter ICs like 4017 to generate signals that control the flashing of LEDs arranged as analogue clock's hands.

Step 1: Stage 1: Clock Signal Generation

First I made a clock generator using 555 IC in astable mode. Using the website (http://www.ohmslawcalculator.com/555-astable-calcu...) I can generate 1 Hz signal with a 100 uF capacitor and two 4.81 k ohm resistors.

In order to set the time, I can add a switch that alternates between the 100 uF capacitor to create 1 Hz clock signal and 1 uF capacitor to create 100 Hz clock signal.

The clock signal from pin 3 (output) will be fed to the next stage (Seconds Generation).

Step 2: Stage 2: Seconds Signals Generation Circuit

Here I connected two 4017 ICs to generate counting from 00 to 59. The first IC is called UNITS IC and can generate counting from 0 to 9. The IC is clocked using the clock signal from the 555 timer (Step 1).

This IC needs not to be reset as the units counting should reach 9.

The Second 4017 IC is called TENS IC and can generate counting from 0 to 5. The IC is clocked using the clock signal from the 4017 UNITS IC as the carry out (pin 12) will create a signal once the UNITS counter reset from 9 to 0.

The IC needs to be reset when the counting reaches 6. So the Q6 output of the IC is connected to reset (pin 12) and goes also to the next stage (Minutes).

Step 3: Stage 3: Minutes Signals Generation Circuit

Here I connected two 4017 ICs to generate counting from 00 to 59. The first IC is called UNITS IC and can generate counting from 0 to 9. The IC is clocked using the clock signal from the 4017 TENS IC counter (Stage 2) of the seconds generation stage.

This IC needs not to be reset as the units counting should reach 9.

The Second 4017 IC is called TENS IC and can generate counting from 0 to 5. The IC is clocked using the clock signal from the 4017 UNITS IC as the carry out (pin 12) will create a signal once the UNITS counter reset from 9 to 0.

The IC needs to be reset when the counting reaches 6. So the Q6 output of the IC is connected to reset (pin 15) and goes also to the next stage (Hours).

Step 4: Stage 4: Hours Signals Generation Circuit

Here I connected two 4017 ICs to generate counting from 00 to 11. The first IC is called UNITS IC and can generate counting from 0 to 9. The IC is clocked using the clock signal from the 4017 TENS IC counter (Stage 3) of the minutes generation stage.

This IC needs to be reset as the UNITS counting reach 2 and TENS counting reach 1.

The Second 4017 IC is called TENS IC and can generate counting from 0 to 1. The IC is clocked using the clock signal from the 4017 UNITS IC as the carry out (pin 12) will create a signal once the UNITS counter reset from 9 to 0.

This IC needs to be reset as the UNITS counting reach 2 and TENS counting reach 1.

As we need to reset both counters at the count of 12 (count 2 of the UNITS IC and count 1 of the TENS IC), we can use AND gate by connecting two NPN transistors in series. the first NPN transistor will be connected to Vcc through the collector. The base is connected to Q2 of the UNITS counter and finally the emitter is connected to the second NPN transistor. The second NPN transistor's base is connected to Q1 of the TENS counter and finally the emitter will be connected to the RESET (pin 12) of both ICs.

Step 5: Stage 5: Seconds LEDs (00-59)

In this stage, I connected 6 groups of LEDs. Each group consists of 10 LEDs representing the counts from 0 to 9.

  • group 0 (G0) represents the seconds count from 0-9
  • group 1 (G1) represents the seconds count from 10-19
  • group 2 (G2) represents the seconds count from 20-29
  • group 3 (G3) represents the seconds count from 30-39
  • group 4 (G4) represents the seconds count from 40-49
  • group 5 (G5) represents the seconds count from 50-59

The Anode of LED 0 of each group is connected to Q0 of the UNITS IC from seconds signals generation circuit. The Anode of LED 1 of each group is connected to Q1 of the UNITS IC from seconds signals generation circuit. And so on until I get the Anode of LED 9 of each group is connected to Q9 of the UNITS IC from seconds signals generation circuit.

All the cathodes of each group's LEDs are commend to one wire connected to the collector pin of an NPN transistor. The base of the G0's transistor is connected to Q0 of the TENS IC from seconds signals generation circuit. The base of the G1's transistor is connected to Q1 of the TENS IC from seconds signals generation circuit. And so on until I get The base of the G9's transistor is connected to Q5 of the TENS IC from seconds signals generation circuit. All the emitters of the transistors shall be connected to the ground of the battery.

Step 6: Stage 6: Minutes LEDs (00-59)

In this stage, I connected 6 groups of LEDs. Each group consists of 10 LEDs representing the count from 0 to 9.

  • group 0 (G0) represents the seconds count from 0-9
  • group 1 (G1) represents the seconds count from 10-19
  • group 2 (G2) represents the seconds count from 20-29
  • group 3 (G3) represents the seconds count from 30-39
  • group 4 (G4) represents the seconds count from 40-49
  • group 5 (G5) represents the seconds count from 50-59

The Anodes of LED 0 of each group is connected to Q0 of the UNITS IC from minutes signals generation circuit. The Anodes of LED 1 of each group is connected to Q1 of the UNITS IC from minutes signals generation circuit. And so on until I get the Anodes of LED 9 of each group is connected to Q9 of the UNITS IC from minutes signals generation circuit.

All the cathodes of each group's LEDs are commend to one wire connected to the collector pin of an NPN transistor. The base of the G0's transistor is connected to Q0 of the TENS IC from minutes signals generation circuit. The base of the G1's transistor is connected to Q1 of the TENS IC from minutes signals generation circuit. And so on until I get The base of the G9's transistor is connected to Q5 of the TENS IC from minutes signals generation circuit. All the emitters of the transistors shall be connected to the ground of the battery.

Step 7: Stage 7: Hours LEDs (00 to 12)

In this stage, I connected 12 groups of LEDs. Each group consists of 5 LEDs representing the count from 0 to 4.

  • group 0 (G0) represents the hours count from 00-01
  • group 1 (G1) represents the hours count from 01-02
  • group 2 (G2) represents the hours count from 02-03
  • group 3 (G3) represents the hours count from 03-04
  • group 4 (G4) represents the hours count from 04-05
  • group 5 (G5) represents the hours count from 05-06
  • group 6 (G6) represents the hours count from 06-07
  • group 7 (G7) represents the hours count from 07-08
  • group 8 (G8) represents the hours count from 08-09
  • group 9 (G9) represents the hours count from 09-10
  • group 10 (G10) represents the hours count from 10-11
  • group 11 (G11) represents the hours count from 11-12

The LEDs are controlled by the TENS count of the minutes signals generation circuit. The Anodes of LED 0 of each group is connected to Q0 of the TENS IC from minutes signals generation circuit. The Anodes of LED 1 of each group is connected to Q1 of the TENS IC from minutes signals generation circuit. And so on until I get the Anodes of LED 4 of each group is connected to Vcc.

All the cathodes of each group's LEDs from 0 to 3 are commend to one wire goes to the control circuit as G0. Except for the cathodes of LEDs 4 are connected to OR gate made with two NPN transistors. The base of the first NPN transistor is connected to Q4 of the TENS IC from minutes signals generation circuit while the base of the second NPN transistor is connected to Q5 of the TENS IC from minutes signals generation circuit. The emitters are commend on one wire with the cathodes of the other LEDs that is labeled G0.

Step 8: Stage 8: Hours Signals Control Circuit

Finally I made two circuits to control the Hours signals. The first circuit is made with AND gate made with NPN transistors.

The first control circuit is made to manage the signals received from G0 to G9 of the Hours LEDs. Each of G0 to G9 are connected to the collectors of 9 NPN transistors. The Bases of the transistors are connected to the outputs of the UNITS IC of the hours signals generation circuit counting 0 to 9. The emitters are commend and connected to the collector of the NPN transistor which the base is connected to the output of the TENS IC of the hours signals generation circuit counting 0.

The second control circuit is made to manage the signals received from G10 to G11 of the Hours LEDs. Each of G10 and G11 are connected to the collectors of 2 NPN transistors. The Bases of the transistors are connected to the outputs of the UNITS IC of the hours signals generation circuit counting 0 to 1. The emitters are commend and connected to the collector of the NPN transistor which the base is connected to the output of the TENS IC of the hours signals generation circuit counting 1.

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