The LED Clock

Well, for the past little while, I’ve been working on a bizarre clock made with LEDs glued into a dollar-store cookie sheet. I got the idea just out of the blue and decided that it would be fun to build. Now, it’s nearing completion so I figured it’d be prudent to document the miserable contraption. I guess I should go through the steps it took to get this thing running.

First, I took one of those dollar store cookie sheets and drilled it through for 40 LEDs. 12 for the hours, 12 for the minutes, 5 for the seconds, 5 more for the div/5 minutes and five more for the outside and the PM light.


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Drilling it wasn’t much fun but, when it was finished, I started to insert the LEDs with the grounds all towards the outside of their respective circle. Then I mixed up some epoxy and drizzled it over the backs of the LED’s. Unfortunately, the epoxy didn’t hold very well on the other epoxy surfaces so I used hot glue to tie them down.


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As you can see, I labeled it in reverse of the other side so that I could get ‘er working. Thus started the long job of soldering the whole thing.


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The image show isn’t the complete one, but it took me several hours to solder it all together. I used 7 groups of 6 LEDs in order to display the image. In this case I used the 7 groups for the duty cycle, thus a 1/7 duty cycle was used. Each of the 7 groups is fed ground through an MPSA13 Darlington transistor. Here’s a picture of the board that controls it.


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Pretty fucking ugly, I know. But it works and I used an MCU (PIC18F4685) that was a little overkill but that’s fine, I’ve got quite a few of those. Anyways, so far so good, though it seems a little impractical as a clock and I think I set the rings of the minutes and hours too close together. Oh well.


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2 thoughts on “The LED Clock”

  1. Well, I developed a matrix and wrote it out on the back face of the clock, if you look at it anyways. that way I could use a minimum of pins.

    Take a look at multiplexing if you’re interested.

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