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LED Chaser with Slow Adjustable Fading Effect

The post discusses a cool chasing LED light circuit that features a timed delay fading slow transition effect across the whole illuminated sequencing LEDs. The idea was requested by Mr. Tamam

Technical Specifications


I want to design a circuit consisting equal no. of Red, Green, Blue, Yellow, Violet, Orange and White LEDs. I want to have these LEDs in a continuous and smooth transition effect like
below,

At first, Red branch of LEDs lit for a preset time then slowly fade out and then Green branch of LEDs fade in and fade out then next branch fade in and so on.....

I would like to have control on transition time delay, light timing, fade in or out timing if possible. And I don't want to use any Programmable IC for this. So please please let me know if it possible without any programmable IC. It is okay even if I need several ICs to accomplish the job. You just show me the way !!

Thank you very much once again for your valuable time and for a quick reply! I am looking forward to you response!!

ABU TOHA MOHAMMAD TAMAM

Circuit Diagram




 


The Design


The proposed chasing, fading LEd light circuit may be understood with the help of the above schematic and the following description:

The upper circuit is a standard LED chaser design comprising of a decade counter IC 4017 and a clock oscillator using IC 555 astable configuration.

This IC 4017 generates a sequencing high logic (equal to supply voltage)  across its entire output pins in response to the clocks at its pin14 from the IC 555.

If we connect LED directly across the 4017 outputs and ground, the LEDs would illuminate in a dot mode fashion from the first pinout upto the last in a sequencing pattern resembling a chasing effect.

This effect is pretty ordinary and we all probably have come across and built such light chasers circuits quite often.

However as per the request the effect needs to be enhanced by adding a slow transition over the LED illumination as it sequences across the entire channel. This fading transition on the sequencing LEds is expected to generate an interesting group LED chasing effect instead of an illuminated dot like appearance.

The above intriguing show could be easily implemented by connecting the LEDs to an intermediate BJT delay generator circuit.

This BJT circuit becomes responsible of generating the intended transition delay over the LED illumination and can be witnessed in the lower design.

This stage needs to be repeated across all the selected outputs of the 4017 outputs for achieving the desired chasing, fading slow transition over the LEDs.

As requested the rate of the above fading slow transition could be controlled by adjusting the given pot.

The circuit is basically a simple delay timer which sustains the illumination on the sequencing LEDs for a few moments depending upon the set value of the pot. The stored charge on the capacitor produces this timed delay effect on the LEDs which could be predetermined as per ones own choice.

The speed of the sequencing could be also altered by tweaking the 555 IC 100k pot as per individual choice which this could in turn interfere with the delay transition effect and thus is a matter of some trial and error until the most attractive set up is determined.

For Improved Fading effect


For an improved fading response the LED could be connected across the emitter and ground of the circuit, as indicated the below given diagram:



Need Help? Please leave a comment, I'll get back soon with a reply!




Comments

  1. dear sir,,source voltage is 12vdc. 3W led draws 700mA current. LED voltage is 3.5v..According to the calculation 15 Ohm resistor to be used. so what will be the wattage of the resistor?

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  2. dear Jayanath, a 3watt, 3.3V LED will require 900mA, not 700mA, so the series resistor will be = 10 ohms

    wattage = same as LED wattage

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  3. sorry wattage = (12 - 3.3) x 0.9 = 7.83 watts

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  4. sir , it means the best suitable is LM317 isnt it?

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  5. Hi,

    Is it possible to run this w/ 3VDC if 555 is cmos-based and resistors replaced w/ correct values for 3VDC?

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  6. Sir how much number of led will run on this circuit and which types led we have to run on this circuit

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  7. 3 to 4 LEDs in series on each channel

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  8. Hello sir you have any circuit like above ones which can run 6...... 50 5mm or 8mm leds Series in parallel each channel have to run 50 leds in series

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  9. Hello Basit, you can use the above circuit for connecting 50 LED by connecting in parallel.

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  10. i would like to install these on my motorcycle as turn signals. would you suggest 1 module with a lot of wiring or 4 separate modules. i can step voltage down if i have to.

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  11. you will have to make and install 4 of the above units on four indicator sides of your motorcycle.

    The second diagram will need to be integrated with each of the output pins of IC2 of the first diagram, the 100k pot can be eliminated if a variable feature is not required

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  12. Dear Sir
    Can you advice on how to make the following circuit
    A single flashing LED circuit, in which the LED flash simulates that of beacon ie when the LED flashes, first it glows slowly, then to full intensity, and then fades. This gives the effect of a rotating beacon OR just like the lights on an aircraft tail.
    A video link to such an effect is following
    https://www.youtube.com/watch?v=zU5gJUx_8ec

    (The various types of patterns shown in this video are not needed, just the simple rotating beacon effect is required)

    The circuit is intended to be used in the car (as a flashing rear light) so the circuit may function on 12v and the LED may be bright enough to be visualized clearly so it may be 1 watt smd led.
    Kindly advise
    Thanks

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  13. Dear Ankit, I'll try to figure it out, and publish it soon if i find it possible.

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  14. Sir pls and the working vedio of this circuit
    ... My circuit is not working properly

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  15. Sir pls and the working vedio of this circuit
    ... My circuit is not working properly

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  16. Sourabh, A video may not be available at the moment, but you can try connecting the LED at the emitter of the transistor for getting an improved fading effect, see the last diagram in the above article.

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  17. Is there any way I can fade in and out string of leds (arranged in series) connected to 4017 pinout. I am planning to make Diwali series for my home which will have the series groups attached in parallel mode to 4017 pinouts. I have googled a lot on this but could not find a concrete solution. I am banking on you for the same. The input voltage is 12V 1A

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  18. you can try the concept that's explained in the above article, use the second transistor driver configuration where the LED needs to be connected at the emitter of the transistors....and make sure the capacitor is connected directly across the base/emitter of the transistors and not after the diode.

    the pot can be eliminated

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  19. Hello sir, the fade out effect is looking nice after connecting a 100uF(testing) 50V capacitor to the emitter and ground.

    Moving forward I have couple of things now,

    i) I have tried connecting another 100uF capacitor at the base and ground to achieve slow fade in effect, it showing up properly however I am not sure whether it is a right approach to do
    ii) How do I choose the capacitance and type of capacitor for the above effects considering total 200 leds. The connections are like total 20 leds to one pin out of 4017 arranged as 5 in parallel each with 4 leds connected in series.

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  20. Hello Neeraj, the fade out and fade in both can be achieved by connecting a capacitor across base and emitter between two resistors in series from 4017 to the transistor base...the capacitor can come between these two resistor and ground.

    the number of LEDs will not affect the results if the transistor is a Darlington type such as a TIP122... or alternatively a Darlington could be configured with two discrete transistors selected as per preference.


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  21. Thank you sir for the quick reply, the first part regarding connecting the capacitor is not clear to me as my level of understanding is low in this context. Can it be possible for you to paste a small circuit diagram so that I can understand the connection points.

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  22. In the last diagram, remove only the pot without disturbing the 100uF, and replace the 1N4148 diode with another 10K resistor...that's all this will allow you to get the suggested results

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  23. ....so the capacitor comes in between the two resistors....capacitor value can be now adjusted for changing the fading timing...use only a Darlington type of transistor.

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  24. Hi Mr. Swagatam
    I am looking for a 11 LED Chaser and it is ruining in a circle. I know the 4017 is limited to only 10 LEDs. Do you know of any IC that can run on 11 LED in the sequence, chasing in a circle.... go on and on and it is also adjustable? kylwal@hotmail.com Thanks

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  25. Hi Kyle, you may have to cascade two ICs to create 11 outputs, you can take the help of the following concept, but for getting 11 outputs one of the IC pins might require a slight modification

    https://homemade-circuits.com/2011/12/how-to-make-18-led-light-chaser-circuit.html

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  26. Sir.
    I have some problems with your circuit reaching my needs, actually i dont intent to use a led running this projects, i intent to use a 12volts 30watts dc bulb to run the projects to suit my need, so i was thinking of doing some modifications, can i replace the BC transistors since they dont and cant run with high Amperes and use BD39 or TIP41 so that it can bright and deam the dc bulbs? i kindly wait your response.
    Your website is the best and thanks for the good job.
    Looking forward to read from you.

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  27. Nkwenti, yes you can replace the shown BJTs with higher rated BJTs, you can use TIP122, or TIP142, because these are Darlington based and will work in a better manner.

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  28. Hi, Could you suggest me a chaser circuit with below needs:-
    1. the circuit should start running lights when it get a single positive trigger from a other circuit.
    2. the LEDs should start from 1-8 and stop. At last, the 8th LED should off in state and no cyclic process. Again if it gets a single positive trigger it should start run and off.

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  29. please look into this circuit. Is the above circuit works like this in youtube? If not please help me to build one.

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  30. No, the circuit indicated in your video is implemented through a programmed microcontroller IC, it cannot be achieved through ordinary circuits using discrete parts

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  31. Ok thank you. I saw these type in buses here in tamil nadu so would like to try one.

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  32. sure, you can try using Arduino programming...

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  33. Hi, how to stop the led cyclic process after one complete rotation? That means all LEDs should be in off state after one cycle.

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  34. Hi, for this pin#11 will need to be used separately without LED.
    disconnect pin#13 from ground and connect it with pin#11

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  35. Hi, I connected pin 11 with pin 13 as u said, but it's not working. Only led on pin 2 blinked once and off. It suppose to complete one full cycle and stop but it didn't. I tried with change of IC also. Could u please help me out.

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  36. It should have worked, I have tested the working.

    Anyway you can try connecting pin#13 to ground with a 1K resistor and then connect pin#11 with pin#13.....or simply keep the existing set up as is, just connect a 1K from pin#13 to ground.

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  37. I need to use a led module at each output which is 125mA. So what transistor I can use?

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  38. you can use 8050, or 2n2222 transistor

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