4-Foot Wooden Digital Clock

User-Contributed Project

User-Contributed Project

This project guide is not managed by MAKE staff.

How to make a 4-foot-long digital clock using mahogany, rice paper, LEDs, plexiglass, 74HC595 and ULN2003 chips, and an Arduino.

  • Author: Wes
  • Difficulty: Moderate
  • Add Note x

Need to know what time it is, but don't own a phone, computer, microwave, or any of the other 100 clocks you probably already have? How about a huge mahogany digital clock to prove your geek prowess?

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Add Note Edit Step 1 — 4-Foot Wooden Digital Clock  ¶ 

  • Get some wood. I chose mahogany.

  • Create a template for your 7-segment digit.

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Add Note Edit Step 2  ¶ 

  • Use a scroll saw to cut the LED segments out of the wood.

  • Use a plunge router to hollow out the back side of the wood.

  • Stain the top side of the wood. I used a satin poly.

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Add Note Edit Step 3  ¶ 

  • Connect the digits together using brass tubes and super glue.

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Add Note Edit Step 4  ¶ 

  • Get some plexiglass and cut pieces to the shape of the LED segments. (I used the scroll saw for this.)

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Add Note Edit Step 5  ¶ 

  • Get a few LEDs (I used blue 5mm).

  • Drill holes in the edge of the plexiglass.

  • Super-glue the LEDs into the holes.

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Add Note Edit Step 6  ¶ 

  • Paint the back and edges of the LED segments with metallic paint.

  • Sand the front of the LED segments. The scratches will diffuse the light.

  • Apply some voltage.

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Add Note Edit Step 7  ¶ 

  • Take 2 thin sheets of plexiglass and sandwich rice paper between them.

  • Hot-glue the LED segments to the plexiglass.

  • Solder wires to all of the LEDs.

  • Hot-glue the plexiglass to the inside of the digits.

  • Connect each of the LED segments to a ULN2003A, and a 74HC595 chip. See the schematic. I also added a 220ohm resistor per LED.

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Add Note Edit Step 8  ¶ 

  • Connect the chips to an Arduino and use the time library to "ShiftOut" the time to the 74HC595s.

  • Stand back (way back) and check the time.

  • Put it up on your cubicle for all your fellow drones to admire!

For more information, check out the Woodworking category page.

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Guide Add Note

Wes: A couple of things.

1. Can you post a complete schematic with power source and voltages, all connections etc? The one that was posted seems to assume that the builder knows a lot more than a beginner? I'm used to following building plans from magazines like QST where there is a parts list and complete schematic.

2. The four foot designation: is that the height of each character, or the length of all four digits? Could you make it as large as you want by adding more LEDs?

Thanks

Rog

Roger Smith III, · Reply

I am afraid that I do not have the software to build a full schematic. The arduino powers it all, which is 5v output. The parts are (1) arduino, (6) 74hc595 shift registers, (6) uln2003a transistor ICs, 92 LEDs, 92 220ohm resistors. The schematic shows how this is used for one digit. Just extend it to the remaining.

Each digit (there are 6 of them) is 6"x9" and the colons (two) are 3"x9" which totals 3' 6". plus 1" of brass connecting each digit. You could scale it up or down as you wish.

Thanks,

Wes

Wes, · Reply

Wes,

for all of the 92 LEDs where did you connect the two wires coming out of each LED? One obviously has to go into the resistor and then the uln2003a, but then does the second wire need to be grounded? And if so then what ground is this wire being connected to? And do you have the coding for the time library?

Thanks,

Nick

nick, · Reply