Picture of Giant Two-Digit Countdown Clock

You don't have to be in Times Square to enjoy large bright displays of lights. You can create that in the comfort of your own home with some foam board, LEDs, and our little friend Arduino.

My sister-in-law decided to get married on New Year Eve, and the venue she chose stays open until 1am that night, so I started thinking it would be great to have a nice big countdown clock. I ran the idea past her and her fiance and they both loved it, so I went to work.

When I made it I intended it for just one use, but it's a very impressive display that can be seen across a huge room.  This is pretty simplified and what I'm showing you is on a breadboard. Optimizing and taking it beyond prototyping (e.g. replacing the breadboard with some pcb boards) are outside of the scope for this but shouldn't be too difficult.

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Step 1: Gather Materials

Picture of Gather Materials
2014-02-22 22.05.32-1.jpg
Materials for this are as follows:

1 20"x30" piece of foam board (any desired color - my sister-in-law was even considering one of those holographic ones for a short while), we're using plain white in this example
1 roll of 12v LED strips (any desired color) (120 LEDs/m recommended but not mandatory)
1 Arduino (I'm using the UNO R3)
1 Breadboard
14 2N3904 NPN Transistors
14 1Kohm Resistors
1 7805 Voltage Regulator
1 12v power source (plug or battery)
1 Soldering iron
Enough wire and solder to connect everything, including jumper wires (I used about 50 the first time)
(optional) 2 seven-segment display modules, if you want to tweak the design before taking it full scale. I'm providing a diagram on how to connect to a typical common cathode display.
(optional) Conductive copper tape
(optional) Liquid electrical tape
kooth1 month ago

Very nice Instructable! This is just awesome!

edwardo18533 months ago
Sweet contact me when you do it. I really want to make one
CatalinRO4 months ago

Good idea to use more LEDs per length unit, I did not use on my project and you can see the pixels :D

frankenroc (author)  CatalinRO4 months ago
Your project was actually one of the big sources of inspiration for this and my next project. It seems you made yours a while back, and I assumed the 120/m LEDs weren't (at least not as readily) available as of the time of your build. Even so, glad I managed to catch your eye with my project.

At that moment I was thinking to put 2 LED strings in parallel with some offset to have more dots on length unit. But I was not sure about how the final display will look like, so I kept it the way it is described in the instructable. Happy to see that my idea was useful and looking forward to see your next project :)

Cool! If you use shift registers you can cut down your Arduino pin usage.

very good suggestion.

Treknology4 months ago

I've actually thought about doing this using 4-foot fluoro tubes and firing them up in "cold" mode. It's amazing how little power they need to be visible as opposed to a source of illumination.

florinc4 months ago

Great idea, nice implementation.

The good thing is that it's scalable, that is, the clock can be made as big as your wall is.


billbillt4 months ago

got my vote

nqtronix4 months ago

I finished something simliar earlier this year.

However my digits look like a standard seven segment display with the typical red color. Unfortunatly I miscalculated the brightnes, so after all it looks a bit dim, especially in direct sunlight. Instead of having a single controller for both segments I included an attiny44 in each panel. This allows control by two wires only, so your main controller can use all of its I/Os. The integration in new project is way easier, too.

I've planed from the very beginning to publish the project on instructables, so I've taken a few dozen pictures. It may take awhile till I find enough time to write about it though.

I almost forgot: You've done great work as well. Just by direct comparison I'd still prefer my version ;)

frankenroc (author)  nqtronix4 months ago

Everyone's a critic, lol. I look forward to seeing your version, though!

I'll probably optimize this as time goes on. I just really wanted to get a proof of concept constructed quickly.

kminnie4 months ago
Ditto, interested if you could make the code for it! A wall mounted clock would be great!
frankenroc (author)  kminnie4 months ago

That's the next planned project. If it goes well I'll post it here, complete with code. But I know there are other clocks already posted with code if you're looking for something now.

edwardo18534 months ago
Is there any way for this to be modified to be a gaint wall clock display?!
frankenroc (author)  edwardo18534 months ago

That's actually my next planned project!

That's great!