Simple Fading LED Light

electronics

ByJayant 12

Fading LED Circuit using 555 Timer IC

You should have seen LEDs glowing and fading in a LED Strip lights, used for decoration in festivals and functions. They look beautiful, and give a different look. This fading LEDs circuit can be created using numerous methods like using microcontroller, ICs etc. But how can we forget our Evergreen IC, 555 Timer IC, yes we can create a fading LED using 555 timer.

 

Required Components

555 Timer IC

Transistor BC547

Capacitor – 10uF

Resistors – 100k, 470 ohm

LED

Battery – 9v

 

Circuit Diagram and Explanation

Fading LED Circuit Diagram

The slow fade led circuit is very simple, 555 has been used in Astable mode and a transistor is used to amplify the current. In Astable mode 555 IC oscillate at a particular frequency (depending on RC components), means output at PIN 3 goes HIGH and LOW periodically. So in our circuit whenever the output at PIN 3 goes HIGH, the transistor starts working as an amplifier, and amplifies the current. This current goes into the capacitor and charge the capacitor to the 2/3 Vcc (555 IC principal), at the same time LED glows. After this, output at PIN 3 becomes low, transistor becomes OFF and capacitor start discharges through the collector-emitter junction. Capacitor discharges into the LED, which gives the LED fading effect. As the capacitor discharges, LED illumination fades. Then again, PIN 3 goes high and capacitor charges and LED illuminates.

 

The led fading time is dependent on the resistors and capacitors value, if we increase the value of capacitor the LED would fade slowly. Like I have demonstrated in video, when I attached another capacitor of 10uf, fading effect becomes slow.

You may also like to build these simple circuits: Simple LED circuitFlashing LED Circuit and Heart Shape LED Flasher.

Video

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Comments

  • Arun's picture
    Arun
    May 23, 2016

    Kindly let me know that pin 2 and 1 are connected or not

  • err404's picture
    err404
    Mar 28, 2018

    They are not, wire connections have a dot to show the connection

  • Serafin Fariñas IV's picture
    Serafin Fariñas IV
    Jun 30, 2016

    Hello and good day!. You have really helped me in my upcoming project. Thank you very much for the help. I have a concern however. My project is size restricted and I am going to use 2 AAA batteries that sums up to just 3 volts. I would like to ask what I should change to compensate with my limited power supply. Thank you very much!

  • Abhishek's picture
    Abhishek
    Jul 09, 2016

    You can even run this circuit on 3v, but use good quality with higher mAh like Duracell etc.

  • unown's picture
    unown
    Sep 22, 2016

    555 runs on 4.5V and above. thanks for the sponsored comment anyway

  • Shariq Zahid's picture
    Shariq Zahid
    Dec 15, 2016

    Sir i want to ask that i have made the circuit but the led is not fading but instead it is glowing steadly.. Can you guide me please..

  • Pavel's picture
    Pavel
    Apr 26, 2017

    Maybe the R1 value is too high. I used trimmer which should be 100kOhm max., but at the maximum position my led was just glowing. When I lowered the trimmer, the LED begun to make the desired fading effect.

  • Abhinandan Sharma's picture
    Abhinandan Sharma
    Jul 26, 2017

    Will this circuit works for a led strip or more than 1 led(s)

  • Abhinandan Sharma's picture
    Abhinandan Sharma
    Jul 26, 2017

    if i use 12v power supply instead of 9v?

  • Sam's picture
    Sam
    Aug 23, 2017

    Hi,
    Please let me know the formula for ON time and Off time for the circuit given as it doesn't have RA and RB resistors.

    With regards,
    Sam

  • D.G Sajith Thushara Dhanapala's picture
    D.G Sajith Thus...
    Apr 08, 2018

    IC pins 5 & 7 are they not connected? just leave?

    thanks.

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