## Thursday, February 16, 2023

What is a Light Chaser

Light chasers are decorative lights or LEDs arranged in different moving patterns which create a chasing light or 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.

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 design 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.

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

Although the above design looks great, it is possible to create even more complex and interesting light effects using the same IC 4017 and IC 555 combination, through some minor modifications, as described below:

LED Knight Rider Chaser Circuit

The first concept presented here is basically a running light effect generator circuit, quite resembling the effect produced over the popular "knight rider" car.
These clock pulses received from the IC555 is translated into a sequencing or chasing effect over the LEDs connected across the various outputs of the IC 4017.

In its normal mode the IC 4017 would have generated a simple start to end sequencing of the LEDs wherein the LEDs would have lit up and shut off one after the other in a sequencing pattern with a rate determined by the IC555 cock frequency, this would repeat continuously as long as the unit stays powered.

However in the proposed knight rider LED light chaser circuit, the output of the IC4017 is configured in a special way using a group of diodes which enable the output sequencing to produce a to and fro chasing of the connected LEDs, albiet through 6 LEDs only in contrast to 10 LEDs as in the normal mode.

How it Works
As can be seen in the first circuit diagram, the design produces a reverse forward moving effect of the LEDs in response to the clocks generated by the IC555 which is basically wired as an astable.

The frequency of this astable can be varied by adjusting the associated 500k pot which in turn influences the LED sequencing speed.

The entire circuit is powered via a compact transformerless power supply circuit thus avoiding the need of bulky transformers or costly SMPS.

This circuit can be also modified for illuminating mains operated bulbs by incorporating a few triacs in conjunction with the LEDs present at the outputs.

The second figure shows the complete arrangement where we can see 6 triacs being rigged across the output LED ends via 1 K resistors.

Again, this mains operated knight rider light chaser does not depend on bulky power supply stages rather employs a simple capacitive power supply for implementing the proposed running light or chasing LeD effect.

What is a Light Chaser

Light chasers are decorative lights or LEDs arranged in different moving patterns which create a chasing light or 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.

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 design 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.

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

Although the above design looks great, it is possible to create even more complex and interesting light effects using the same IC 4017 and IC 555 combination, through some minor modifications, as described below:

LED Knight Rider Chaser Circuit

The first concept presented here is basically a running light effect generator circuit, quite resembling the effect produced over the popular "knight rider" car.
These clock pulses received from the IC555 is translated into a sequencing or chasing effect over the LEDs connected across the various outputs of the IC 4017.

In its normal mode the IC 4017 would have generated a simple start to end sequencing of the LEDs wherein the LEDs would have lit up and shut off one after the other in a sequencing pattern with a rate determined by the IC555 cock frequency, this would repeat continuously as long as the unit stays powered.

However in the proposed knight rider LED light chaser circuit, the output of the IC4017 is configured in a special way using a group of diodes which enable the output sequencing to produce a to and fro chasing of the connected LEDs, albiet through 6 LEDs only in contrast to 10 LEDs as in the normal mode.

How it Works
As can be seen in the first circuit diagram, the design produces a reverse forward moving effect of the LEDs in response to the clocks generated by the IC555 which is basically wired as an astable.

The frequency of this astable can be varied by adjusting the associated 500k pot which in turn influences the LED sequencing speed.

The entire circuit is powered via a compact transformerless power supply circuit thus avoiding the need of bulky transformers or costly SMPS.

This circuit can be also modified for illuminating mains operated bulbs by incorporating a few triacs in conjunction with the LEDs present at the outputs.

The second figure shows the complete arrangement where we can see 6 triacs being rigged across the output LED ends via 1 K resistors.

Again, this mains operated knight rider light chaser does not depend on bulky power supply stages rather employs a simple capacitive power supply for implementing the proposed running light or chasing LeD effect.