This Is a 4-bit Binary Counter

I made a 4-bit binary counter with an IC I had lying around . The IC is a SN74LS90 binary counter , it takes in a clock input and produces a BCD output which can be seen through the use of some LEDs . The IC is preset to decimal 9 so the counter goes from 0 to 9 and then resets back to zero. If you do not have a clock then you can check out my instructables on how to make one using a 555 timer .

For this counter you will need :

5V battery

SN74LS90

CLOCK

200 ohm (x4) (R1 - R4)

LED (x4) (D1 - D4)

Wire the IC , resistors and LEDs according to the above schematic . Pin 12 feeds a signal back to pin 1 . Pina 8 , 9 ,11 and 12 are the BCD outputs and connect to the resistors and LEDs .Pins 2,3,6 and 7 are the set and reset pins of the IC and can be used to change the preset value of the IC , but I just connected them all to ground in order for the IC to enter count mode as shown in the datasheet. Lastly pin 5 is the 5V pin and pin 10 is ground .

Note that the 'C' shaped mark at the top of the IC tells us which side of the IC pin 1 is located at .

If you are not sure how to convert binary to decimal then you can use the table above . If you want to know how to get the decimal value without the table , then the place value for the digit on the right of the binary number is 1 and the place value for the digit second from the right is 2 and then 4 for the third digit and 8 for the fourth digit .You can just add the place values in order to get the decimal number . Remember that you should only add the place value if there is a one in that place and not if there is a zero .

If all your components are working and you connected everything according to the schematic then you should see the LEDs blinking in a repeating pattern (from 0 to 9 in binary ) . It should look something like in the image above , now note that I am using the Arduino just as a power source , it is not important for the counter .If your circuit is not working then it could be because your IC if faulty or it could be an issue with your power source , so you could try to replace the IC or your battery.