This project is the last project of the trilogy of binary counters before beginning to work with my Binary Clock. They are Green Binary Counter, 2-Digit Binary Counter, 4-Digit Yellow Binary Counter, this project. In the present project, I'll be using 4-IC7490, 1-IC555, 16 diodes: 1N914, 16-5mm LED, 2-4.7K resistor, 1-100uF capacitor, and 1-Normally Closed (NC) Push Button Switch.

Step 1: List of Materials

4-14 pin socket

1-8 pin socket

4-IC7490 counter

1-IC555 timer

1-PCB, 9cmX15cm

16-1N914 diode

16-5mm LED

2-4.7K resistor

1-100uF capacitor

1-NC Push Button Switch

Step 2: Schematic

Follow step by step the project's diagram so that you can finished it successfully.

Step 3: Beginning the Project

Begin installing the 5 sockets for the integrated circuits and also identify at least the pins 12, 11, 9, and 8 of IC7490 so that you can connect the positive side of each diode (1N914) for leaving free the negative terminal to be connected to its respective LEDs.

Step 4: Working Digit 1

Connect the negative terminal (black line up of the diode's body) from its respective diode coming from the pins 12, 9, 8, and 11 of IC7490 to LED 1, LED 2, LED 3, and LED 4 correspondingly. Also note that you have to connect the negative terminal of each LED to a common point while connecting pin 12 to pin1 each other of this same integrated circuit and you should leave free pin 11 without forgetting solder the connections done on pin 8 and pin 9..

Step 5: Working Digit 2

Repeat step 4.

Step 6: Working Digit 3

Repeat step 4.

Step 7: Working Digit 4

Repeat step 4 and connect pin 14 of IC7490 to pin 3 of IC555.

Step 8: Doing Any Connections

In the back side of your PCB and from the left to the right, connect pin 11 of IC7490(Digit 1) to the next IC7490(Digit 2) in its pin 14 and from the same IC7490 (Digit 2) draws a connection from pin 11 to the next IC7490 (Digit 3) in its pin 14 and from the same Digit 3 draws a connection from pin 11 to the next Digit 4 to its pin 14. Also connect the negative terminals from the set of LEDs and the IC7490s.

Step 9: Completing the Project

For completing, do the rest of connections and install the resistors ans the capacitor.

Step 10: Installing the Integrated Circuits

Install the integrated circuits, the 4-IC7490 counter and the IC555 timer.

Step 11: Connecting the NCPBS

For connecting the normally closed push button switch, it's necessary to cut the the green wire between the pin 14 of IC7490 (Digit 1) and pin3 of IC555 timer and so can connect the red wires to the swith like showed in the photo.