Scrolling, Chasing RGB Circuit

A basic RGB (Red, Green, Blue) moving or scrolling LED display can be created utilizing a few 4017 ICs. Let’s understand the process in detail.

RGB LEDs are becoming very popular nowadays because of its three-in-one color feature, and since these can be powered alone making use of three distinct supply options.

I have previously mentioned one fascinating RGB color mixer circuit, that are available to manually set the color intensities of the LEDs for creating exclusive color combinations by means of constant transitions.

In the offered RGB scrolling LED circuit we include the identical LED for applying the impact.

The following image demonstrates a regular RGB LED with unbiased pinouts for managing the three inserted RGB LEDs.


We’ll need 24 of these LEDs for generating meant scrolling impact, as soon as obtained these types of might be constructed serially as demonstrated in the following image:


As may be seen, the cathodes are all made common and grounded via personal 100 ohm resistors (linked to the harmful supply f the circuit).

The anode ends can be viewed chosen with some appropriate figures that ought to be properly associated with the specific output pinouts of the IC 4017 circuit as proven in this article figure:

The circuit working could be known with the aid of the following factors:

We are able to refer to four IC 4017, 10 phase Johnson’s decade counter/divider device which can be cascaded in a special way such that the designed scrolling consequence is accomplished from the design.

Pin#14 which can be the clock input of the ICs are all connected with each other and built-in with a clock source, which may be very easily attained from any regular astable circuit such as a IC 555 atable, transistor astable, a 4060 circuit or simply a NAND gate oscillator circuit.

The speed of the frequency set on the astable circuit chooses the speed of the scrolling impact of the LEDs.

When power is turned on, C1 immediately causes pin#15 of IC1 to go high briefly. This pulls pin#3 of IC1 to a high while the left pinouts of IC1 are all set to zero logic.

With pin#3 of IC1 heading high leads to pin#15 of IC2 to also go high, which likewise puts pin#3 of IC2 at a high logic and all its other pinouts at logic zero……this in turn causes IC3 and IC4 to undergo an equivalent set of pinout orientation.

So during power turn on all the 4017 ICs achieve the above condition and stay disabled making certain that at first all the RGB LEDs are kept turned OFF.

In spite of this the instance C1 charges fully, pin#15 of IC1 is pleased from the high produced by C1, and now it’s capable of react to the clocks, and in the method the high logic series from its pin#3 moves to the next pin#2….the first RGB string now lights up (first RED string lights up).

With pin#3 of IC1 getting low, IC2 too now turns into allowed and quite in the same way gets prepared to answer the following clock at its pin#14.

Consequently the instance IC1 logic sequence shifts more from its pin2 to pin4, IC2 satisfies by pressing the pinout high from its pin#3 to pin#4….the next RGB string now lights up (green string lights up and substitutes the earlier red LED string, the red being moved to the next RGB string).

With the succeeding clocks at pin#14 of the ICs the similar is accompanied by IC 3 and IC4, such that the RGB string now seems to be shifting or scrolling across the provided 8 succeeding LED strips.

As the sequencing continues across the 4 cascaded 4017 ICs, eventually of time the last logic pulse actually reaches pin#11 of IC4, the moment this occurs the high logic at this pin immediately “pokes” pin#15 of IC1 and pushes it to reset and go back to its primary position, and the cycle begins afresh….

The above RGB scrolling consequence might not be too amazing, because the moving pattern could be in the manner R> G> B……, that is one color occurring behind the other.

To be able to attain a much more attractive appearing pattern in the manner R> R> R> R> G> G> G> G> B> B> B> B…..and so on, we have to apply the following circuit, it displays a 4 channel design, for additional number of channels, you might basically continue adding the IC 4017 ICs in the identical, fashion as demonstrated in the diagram.