Octal counter with line decoder
Electronic
74HC00, 74HC02, 74HC191

In this project, we're going to light up one of the eight LEDs, using an octal counter and an octal line decoder. Look at the schematic for the project. You'll see that the counter's output is taken from Q0 - Q2.

This output is decoded by the octal line decoder made up of a NAND gate and a NOR gate to light up the eight LEDs.

Figure 1 shows the relationship between the outputs Q0 - Q2 (A - C) and the LEDs.

When you finish wiring, turn power ON and see which LED is ON. Take a look at Figure 1, and you'll see that you can tell about the outputs Q0 - Q2 from the LED which is lit.

Now press S1 to send out the pulses. The counter IC counts the pulses and lights up the LEDs one by one as shown in Figure 1.