Simple LED Chaser (Running LED)

Simple LED Chaser (Running LED)

Introduction

Here we are going to make LED chaser. The chasing illusion of frequently turning ON and turning OFF of adjacent LED in a string of LED is called LED chaser. LED chaser circuit mainly consists of two circuits. one is of IC555 and another one is of IC4017. The IC555 circuit is mainly used for providing free running frequency output. and IC4017 is binary decade counter. which can count up to 10 states.

Circuit diagram

Simple LED Chaser(Running LED)

Components required

• IC – CD4017 – 1no
• IC – NE555 – 1no
• Variable resistor – 20k – 1no
• Resistor – 180ohm – 1no
• Capacitor – 47uf/25v – 1no
• Capacitor –  22uf/25v – 1no
• Diode – 1N4001 – 1no
• LED – 5mm,Blue – 20nos
• Battery – 9v – 1no

Working

The 555 timer IC is configured to work in astable mode. Which means, the output from the 555 timer changes continuously between high (Supply Voltage) and low (0V). In other words, if you connect an LED between the output of 555 timer and ground, the LED flashes/blinks continuously.

This pulsing output from the 555 timer is connected to the clock input of 4017 IC. It has 10 output pins and we have connected an LED to each output. By default, the first output pin is on/high and the rest are off. Each time the clock input pin of 4017 IC detects a rise in voltage (from low to high), it turns off the current output and turns on the next sequential output. This swapping of outputs which looks like the LED's are chasing each other, continues until the last LED and then the output resets back to the first LED.