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.

Please refer below link for more about ic 555 astable multivibrator

ic555 astable multivibrator

Step 1: Materials Required

1. IC555

2. IC4017

3. LED

4. PCB Universal Breadboard

5. Connectors

6. Capacitors ( 47uf,.01nf)

7. Power source 5v

8. Wires

9. Resistors ( 100 ohm)

10. Resistor pot ( 10k)

Step 2: Circuit Diagram and Explanation

Please visit the given below link for more about ic555 astable multivibrator

astable multivibrator

IC 4017 is a 16 pin out ic. which can count up to 10 states. IC 4017 mainly consists of two internal blocks

1. Counter

It has 3 inputs and 4 output.

inputs are

1.clock input ------ connected to 14th pin of ic4017

2.reset---------------connected to 15th pin of ic4017

3. clock enable-----connected to 13th pin of ic4017

The output will be in the format of a 4bit binary code

eg; 0000 or 1001 or 0111

2. Decoder

The decoder converts the binary number to decimal number. Here, each output pin of ic4017 is referred to a decimal number. according to the input, the decoder decides which pin has to go HIGH.

conversion of binary to decimal

0000 -----> 0
0001------> 1

0010------> 2

0011------> 3

0100------> 4

0101------> 5

0110------> 6

0111------> 7

1000-----> 8

1001------> 9

Pins of ic4017

1.) Pin 16

it is the positive power supply

2) pin 8

it is the ground

3) Pin 13

it is the Clock enabled pins to controls the clock.When it is “0” logic, the clock is enabled and the counter advances one count for each clock pulse. When “1” logic, the clock input is stopped, and the counter does nothing even when clock pulse arrives.

4) Pin 14

It is the clock triggers one count.

5) Pin 15

It is the reset pin. Normally, it is “0”. When made “1”, the counter is reset to “0”.

6) Pins 1-7 and 9-11

They are the decoded output pins. The active count pin goes high and all others remain low

7) Pin 12

it is the Carry output, for the clock input of an additional counter or an external circuit that the count is complete.

Step 3: LED Chaser With IC4017 and IC555

Circuit the diagram as shown in the figure.

Step 4: Connect Ic555 to Ic4017

since I already have developed astable multivibrator. The output of the astable multivibrator is connected to the clock input of the ic4017. The speed of the running light can be varied by changing the resistance of the ic555. make sure both the circuit have common ground.