## Tuesday, April 25, 2023

10 Simple LED Chaser Circuits Explained [Knight Rider, Scanner, Reverse-Forward, Cascaded]

The article discusses the construction of 10 interesting yet simple LED chaser circuits, which not only create beautiful running light effect but are also easy to build.

We also discuss how to modify these into a design popularly known as "knight rider" chaser circuit.

These primarily incorporate LEDs as well as mains operated bulbs through triacs. The proposed circuit is transformerless and is thus a lot compact and light weight.

What is a Light Chaser

An LED light chaser circuit is a device which is designed to turn ON and OFF a string of LED lamps so that it creates a "running" light kind of effect.

These look very interesting and are surely eye catching and that’s why these types of lighting arrangement have gained immense popularity in today’s world.

1) Simple LED Chaser Circuit Diagram

Though the more complex lighting might need the incorporation of microcontroller ICs, simpler yet very interesting light effects can be generated through ordinary ICs like IC 4017 and IC 555 as shown below.

This is our first LED chaser design which requires very few components for the configuration.

As can be seen in this configuration, in response to the pulses from IC 555, the IC 4017 generates a running or chasing light pattern across the connected 10 output LEDs. The chasing pattern goes on repeating itself from start to finish as long as the IC 555 keeps pulsing pin #14 of the IC 4017.

How to Calculate the Chaser Speed

The chaser speed can be easily adjusted by determining the correct frequency rate of the IC 555, as explained below:

Formula for IC 555 frequency is = 1/T = 1.44 / (R1 + R2 x 2) x C, where R1 is the resistor between pin#7 and the positive line, R2 is the resistor between pin#7 and pin#6/2. C is the capacitor between pin#6/2 and ground, and should be in Farads.

TL = 0.693 x R2 x C (TL refers to time LOW or the OFF time of the frequency)

TH = 0.693 x (R1 + R2) x C (TH refers to time HIGH or the ON time of the frequency)

D = Duty Cycle= (R1 + R2) / (R1 + 2R2)

Or,

R1 = 1.44 x (2 x D-1) / (F x C)

R2 = 1.44 x (1 - D) / (F x C)

The lights connected are mostly LEDs, however it can be modified for using with mains operated lamps also.

10 Simple LED Chaser Circuits Explained [Knight Rider, Scanner, Reverse-Forward, Cascaded]

The article discusses the construction of 10 interesting yet simple LED chaser circuits, which not only create beautiful running light effect but are also easy to build.

We also discuss how to modify these into a design popularly known as "knight rider" chaser circuit.

These primarily incorporate LEDs as well as mains operated bulbs through triacs. The proposed circuit is transformerless and is thus a lot compact and light weight.

What is a Light Chaser

An LED light chaser circuit is a device which is designed to turn ON and OFF a string of LED lamps so that it creates a "running" light kind of effect.

These look very interesting and are surely eye catching and that’s why these types of lighting arrangement have gained immense popularity in today’s world.

1) Simple LED Chaser Circuit Diagram

Though the more complex lighting might need the incorporation of microcontroller ICs, simpler yet very interesting light effects can be generated through ordinary ICs like IC 4017 and IC 555 as shown below.

This is our first LED chaser design which requires very few components for the configuration.

As can be seen in this configuration, in response to the pulses from IC 555, the IC 4017 generates a running or chasing light pattern across the connected 10 output LEDs. The chasing pattern goes on repeating itself from start to finish as long as the IC 555 keeps pulsing pin #14 of the IC 4017.

How to Calculate the Chaser Speed

The chaser speed can be easily adjusted by determining the correct frequency rate of the IC 555, as explained below:

Formula for IC 555 frequency is = 1/T = 1.44 / (R1 + R2 x 2) x C, where R1 is the resistor between pin#7 and the positive line, R2 is the resistor between pin#7 and pin#6/2. C is the capacitor between pin#6/2 and ground, and should be in Farads.

TL = 0.693 x R2 x C (TL refers to time LOW or the OFF time of the frequency)

TH = 0.693 x (R1 + R2) x C (TH refers to time HIGH or the ON time of the frequency)

D = Duty Cycle= (R1 + R2) / (R1 + 2R2)

Or,

R1 = 1.44 x (2 x D-1) / (F x C)

R2 = 1.44 x (1 - D) / (F x C)

The lights connected are mostly LEDs, however it can be modified for using with mains operated lamps also.