Six digit LED clock

Got a bag of LEDs handy? Why not build a display with them? We’ve seen a lot of clocks that make use of LED modules but soldering your own is a fun pastime. [Vadim Suhovatih] did just that using 130 LEDs to build this clock. Each segment of the 7-segment digits consists of three LEDs in parallel which are switched by some 2N4401 transistors. An ATmega328 in the form of an Arduino controls the device with the aid of a DS1307 real-time clock for timekeeping and a 4017 decade counter to assist with scanning the display. Check out the demo after the break.


  1. juancubillo says:

    I have 10K LEDs @ home. lol . Maybe I should do something like this.

  2. TheFish says:


    were did you get 10000 leds?!?!

  3. juancubillo says:

    I used to sell components @ school… bought them from china for about $80 3K reds, 3K greens, and 4K yellows. only sold about 200 when I stoped going to that school. now I have them all on a box. I REALLY should make a huge LED matrix and scroll some mesages

  4. JB says:

    @juancubillo: Can you post where you got it from? $80 for that many LEDs is a very good price. Allows you to throw LEDs at pretty much any project you want without thinking about it :)

  5. fartface says: I bought a crapload of super bright red and white ones for $10.00 for 1000 larger quantities had even better deals.

    They are china 2nd’s that have not been tested but who cares. I have only ran into a couple of dead ones.

    I even found some 10mm .5watt jumbos in a water clear for dirt on ebay.

  6. fartface says:

    oh yeah…

    REal men use these… A clock that can blind you and eat kittens….

  7. juancubillo says:

    Yup… ebay is your friend for these sort of stuff. And yeah, LEDs came from china. They probably won’t be as much quality as german-made LEDs.. but I don’t care, they are for personal use or to sell to students. It’s not like they will end up on medical equipment lol

  8. Whatnot says:

    10K LED times 20mA, that can become a sticky issue when it’s time to power up.

  9. Haku says:

    10,000 LEDs should be enough for a Burning Man costume, don’t know where you’d hide the generator though :D

  10. juancubillo says:

    I feel like i’m stealing Vadim’s post but… What would you guys do with so many of these leds??? i’ve only thinked about a message scrolling led matrix… :S

  11. Vadim says:

    Hhh you can always make a LED cube (21*21*21)
    Thats going to be something else :)

  12. itrolu says:


    I’d personally make a 16x16x32 LED matrix and figure out some tactile interface to manipulate stuff displayed in it (think Powerglove w/o the gay factor) and have them arranged red, yellow, green on the horizontal planes from top to bottom.

    Other uses for the matrix would be audio visualization, visualizing data from wireless nodes around the house (ambient/room temp, utilities usage, ambient light levels, wind, current rainfall rate and so on). RFM22 at 6EUR a pop would make the nodes quite cheap too.
    Even better – your average laptop’s resolution and processing power would make it a better visualization medium, while the 3D aspect of the matrix would make it better for the tactile input part. See if you could add some LED sensing a-la and it could become a very interesting HMI project.

    Hm, how much was the shipping cost on the 10k package?

  13. juancubillo says:

    You would be surprised by the size of a 10k leds box. take 2 shoe boxes side by side and it’s probably even smaller. Shipping was quite cheap about 2 years ago when I bought it.

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