Decade down counter with display
74HC00, 74HC191, 74HC4511
In this project, we're going to make a down counter that can display the numbers 0 - 9 on the LED display, using a counter IC and a decoder IC. As we found, a down counter can count the numbers downward from 9 to 8, 7, 6.. and so on when the pulses are input.
The schematic lets you see that the counter IC output is taken from Q0 - Q3. This output is decoded by the decoder IC and displayed on the LED display.
When you finish the wiring, turn power ON and you'll notice that 0 is displayed on the LED display.
Tap S1, and 0 changes to 9 ..
Tap S1 a few times, and the number changes to 8, 7,6, 5..and so on.
S2 is a reset switch for resetting the count to 9. Press it and see if the
number on the display changes to 9.