Marching LEDs
Electronic
74HC00, 74HC76

Make way for the parade of marching LEDs!

This project lets you send LEDs "moving" as you press S1.

When you finish the wiring, LED 1 lights and starts flickering (you might also have other LEDs light; this is normal). Set the select switch up and keep pressing S1. First LED 2 lights, followed by LEDs 3 and 4.

As you keep pressing S1, you'll have LEDs 2, 3 and 4 lighting in turn. It looks just like a parade of LEDs marching down the street. While pressing S1, try quickly setting the select switch down. What happens?

The LEDs come to a screeching halt. The LEDs are either lit or off just like they were the instant you set the select switch down.

Now set the select switch again up. The LEDs again starts "marching." While you have the select switch at the up position, stop pressing S1 and watch what happens to the LEDs. Can you guess why this takes place?

This project also uses the "flip-flop" IC. You can easily see why this device is so useful in electronics!