What has 114 LEDs and is always running?

The answer, of course, is a word clock. This is actually [Eric's] second version of a word clock. Like the first one, it uses 114 LEDs to back light the words on the display.

In his first iteration he used an Arduino to drive a Charlieplex array of lights. It was an 11 by 10 grid, plus four LEDs to display the in-between minutes as dots at each corner of the clock face. This time around he’s still using an Arduino, but the lights have seen a huge upgrade. In one of his build pictures you can see the reel of RGB led modules which have two RGB LEDs and an HL1606 driver on each segment. These are SPI controlled, making them easy to hook up, using just a few data and power bus rails. Check out the test video after the break that shows what this grid is capable of.

In case you can’t figure out what time is displayed above, you might check out an English version of a Word Clock face to help in your own build.


  1. B0b says:

    >In case you can’t figure out what time is displayed above,

    It’s ten past twelve. ;)

    Beautiful clock.

  2. zacdee16 says:

    I’m no German expert, but a friend of mine who took 4 years of German told me it says “It is Ten after Twelve”.

  3. FlorinC says:

    Another English version of the word clock is ClockTHREE, check it out here:


    (also available for purchase as a kit).

  4. dext3r says:

    very nice!

    any description of the technique used for the faceplate? obviously laser cut, but how? i see an Xacto used to remove the inside of the lettering, but how are things like the inside of “R” held in place?

  5. Frank says:


    Those word clocks have been around for quite some time by now, you can find a nice instructable at http://www.instructables.com/id/The-Word-Clock-Arduino-version/ for instance. I do remember a loooooooong forum thread over on microkontroller.net about those clocks, think it was at http://www.mikrocontroller.net/topic/156661#new for those of you who speak German. The faceplate probably is screenprinted on acrylic glass, I do remember someone at the MK forum ordering a couple dozens/hundreds of those, to be sold among the forum members. :D

  6. giacomo says:

    Ah, I’ve been meaning to build one of these beauties for a while. Very nice. Now I have to come up with a way to improve upon the design, because I can’t just build the same thing :)

  7. Diego says:

    Wunderbar! ;-) really cool!

  8. Nippey says:

    For hose of you speaking German (as I do ;) check out this Link:


    This is the complete concept including an English front-end.

    At the bottom of the page you’ll find two different ways of realization, as not everyone in the mikrocontroller-community wants to do things the same way ;)

  9. David says:

    Is it just me, or does a word clock look cooler in german, than it does in english ?

  10. eok says:


    its my clock.

    to answer some questions…

    the clock face in the pictures is just a b/w print on heavy paper on a A0 printer. it is 50x50cm. and it is mounted like any picture in this 15€ ikea pictureframe.
    front = glass
    printet paper
    then backpanel with led-strips
    wall.. ;-)

    but the “printed paper” solution is just a workaround until i upscaled my small 25x25cm cnc up to 60x60cm. then ill make a nice lasercut face for the v2 as well. in my flickr stream you can see the lasercut workflow from the v1 clock.


  11. eok says:

    did i mention that every time you powercycle the clock she comes up with a differen color? ;-)
    so white is not the only color i use.
    you can get red, green and blue. and yellow, cyan and magenta as well.
    just replug the power cord and the next color comes up. i used a eeprom address in the arduino to remember the last color before the power disconnected and setting the new one on bootup for the next cycle.

    • dave says:

      Hey that is cool, What if it had an idea of my schedule and colored the time accordingly. ie : If its almost time for me to leave for work, it goes orange, then red…

      • eok says:

        no problem dave. implementing that is just a matter of some simple lines of code.

        color = white
        if time is between a and b then color = orange
        if time is between x and y then color = red

        i use something similar for birthday remembering already. pls look at this feature here my v1 clock:

  12. that1guy says:

    As cool as this is, I’m disappointed because I’m working on basically the exact same thing right now.

  13. eok says:

    since some asked…

    i made a quick step by step:
    “how do i design a charlieplexing led array wit easy wiring”


    you can easily scale it, since the principle is every time the same.

  14. Philippe says:

    Where to get the RGB strips???

    • eok says:

      i got mine from ebay.
      it was a seller directly from china.
      but adafruit is selling them as well and others too. just search for “HL1606 5v” and choose a seller you trust/like.

  15. Philippe says:

    Thanks a lot !

  16. Lewis Walsh says:

    I put together a web version of one of these. Probably not of great interest compared to the hardware versions but I thought I’d share:


  17. Roger says:

    Can you share the code for this arduino clock pls.

  18. Markus says:

    I built a similar clock. Checkout my blog (german) http://tiny.cc/2qv5kx

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