Instructables
Picture of Arduino-powered LED Clock
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A fun, simple LED clock, that will give you the time to the nearest half hour using single-color LEDs. Parts needed are as follows:

  • Arduino Nano
  • 400 tie-point Breadboard
  • Ribbon Cable
  • DS1307 RTC IC
  • 32.768 kHz Crystal
  • (12) 10mm LEDs
  • (12) 180 Ohm resistors
  • (2) 10k Ohm resistors
  • 0.1" spaced, 12 wire ribbon cable, 7" long
  • Jumper wires
  • 18" x 6" 1/8" acrylic

The tools needed for this job are:

  • Laser Cutter
  • Soldering iron, flux, solder
  • Wire cutter
  • Wire stripper
  • Needle-nose pliers
  • Vice (optional)
  • Hot glue gun
  • Arduino IDE installed on a computer
 
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Step 1: Laser-cut clock casing

Picture of Laser-cut clock casing
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The first thing that needs to be done for this LED clock is to design the clock case! This gives the layout of your LEDs as well as a good housing to use to help keep the assembly very neat and simple. I attached my illustrator file that can be used on a laser cutter with 1/8" acrylic and is designed to snap together.

Step 2: Place LEDs in holes

Picture of Place LEDs in holes

The easiest way I have found to assemble this clock is as follows:

  1. Clamp the clock face in a vice and angle it so the engraved side faces downward
  2. Drop the 10 mm LEDs in the back of the clock in each of the 12 holes
SoHa SMART1 month ago

Great instruction, as always, Nextfab...love how you guys can answer any/all questions with precision!

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NextFab (author)  SoHa SMART27 days ago

Really enjoy your visits to make with us, Lavon!

Very neat and great project, but I have a question: why can't we just use an arduino uno to light up each led alone one after the other with time interval of one hour and then loop the code to be fully working clock? And another question, what's the use of the crystal and the ic? Thank you
NextFab (author)  • The Inventor •1 month ago

Well the Arduino cannot, by itself, maintain accurate time information. The IC is a Real-Time Clock (RTC) and it is used along with the crystal oscillating at 32.768 kHz to keep perfect time. Thanks to the CR2032 battery, the RTC keeps the time even after the Arduino is unplugged, which prevents the need for reprogramming every time the Arduino loses power. This RTC is accurate at storing the second, minute, hour, day, month, and year. While this clock only displays the time accurate within a half-hour, the code is storing the full time and date data so this Instructable was designed with extra features allowing other makers to take this design and build onto it. For example, using RGB LEDs, you can use different colors for the hour and minute hand and display much more precise data, or an LCD screen can be added to display the date.