Simple RGB flasher

rgb flasher

This project is designed to fade between seven different colors using an RGB LED. To keep things simple, Flakko decided to avoid PWM using a microcontroller. He used a binary counter to cycle through the color sequence. To do the fading between colors he added an RC filter. It’s a pretty simple device and the parts are more common than the ones in the Bit-tech article he referenced. YouTube video of the fader.

[thanks Javier Flores]


  1. furtim says:

    Hooray for YouTube, at least when it comes to hosting hack videos.

  2. cOURTLAND says:

    First Post… and how benificial is this to our lives? “Flashing colors!”

  3. pete says:

    haha courtland, exactly my thoughts :P

  4. Jcg says:

    wel, you could make a nice light for your girlfriend, that could be good for your relation ;)

  5. Br0 says:

    if this faded slower, it would make an awesome mood light, If thrown inside a brushed/translucent object (square, orb, pyramid, cylinder, etc).
    I am interested

  6. Ben says:

    @5, slower fading is accomplished by increasing RxC of the RC timers involved. Multiply the capacitor values by the number you want to multiply the fade times by. You can also fiddle with the resistors, but those work in combinaton with eachother and the transistors.

  7. pretorious says:

    isn’t this simmalar to those pens that everyone seemed to have about 6 months ago? they had a clear body that was iluminated by an led that changes colors… although that circut fit inside a pen…

  8. daniel says:

    cool, a friend of mine wanted to build something like that (but with more leds) for his hookah table so the water was illuminated… might point this out to him, tho he has probably never in his life touched a resistor…

    question: for this case (a led-circle of about 10 cm diameter), would it work with simple red, green and blue leds or should i stick to the rgb ones (presumably more expensive and harder to find)?

  9. morcheeba says:

    #7 They have flashing RGB leds that do something similar:

    … but if you wanted to light a larger area, it would be probably be impossible to keep a bunch of these LEDs synchronized.

    Also, if he had used FETs instead of transistors, the filter capacitors could have been smaller and/or the fading even slower.

  10. If all you want is a slow trippy LED colour changer, you can buy triple-die LEDs with the control circuitry built into them – they’re normal-looking two-lead water-clear LEDs, and to make them work, you just connect them to about three volts. Two alkalines in series can run a bunch of them in parallel.

    They get out of sync pretty fast, but I consider that to be a feature rather than a bug; the cheap ones also have a pretty high incidence of LEDs that don’t quite cycle colours right, but they’re so _very_ cheap that nobody cares:

  11. tecNik says:

    I agree with D. Rutter. Over complicated! Even if you wanted a Sync’ed system this could be done with a simple PIC system. Title is wrong this is not a simple system for the effect.

  12. strider_mt2k says:

    Once again the sweaty, clueless masses miss the point. (sigh)

    Getting a bit predictable around here…

  13. daniel says:

    why missing the point?
    people are commenting on the hack and providing /constructive/ criticism and room for improvement as well as alternatives… i don’t see what’s wrong?

    or, i’m missing the point of your post…

  14. ex-parrot says:

    the schematic seems to be incorrect… I think all the LED resistors should be 220 ohms and that the capacitor on the 555 should be 10uf not 100uf…. at least from the parts list that’s what I got

    any suggestions?

  15. ex-parrot says:

    and the potentiometer value is wrong!

  16. Arram says:

    My hacking days are starting as soon as I get my soldering iron. Would this be a good first project?

  17. ex-parrot says:

    okay there are lots of problems in the schematic now that I’ve built it… esp. concerning the 555 section… I suggest using the 555 section from the linked bit-tech article instead.

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