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I'm in the process of making a Word Clock, and one of the things that I wanted to build for this project was a fairly simple 8 x 8 LED matrix.

This instructable deals with how to build an 8 x 8 LED matrix and controller that can be interfaced with an Arduino microprocessor.

Parts:

  • 64 LED (I'm using 5 mm White LED with a forward voltage of 3.5 V and a load of 20 mA);
  • 1 10 uF electrolytic capacitor;
  • 1 x 0.1 uF ceramic capacitor;
  • 1 x 10 k ohm resistor;
  • 1 x MAX7219CNG Serially Interfaced, 8-Digit LED Display Driver;
  • lots of wire
  • plywood and 10 mm pine for case and matrix body
  • 800 GSM card for cells
  • 1 Arduino Uno

One of the things that I found a little frustrating was that I couldn't find an example of what I was trying to do on the Interweb. Oh, sure ... there were plenty of examples of how to make a controller for your prepackaged Dot Matrix Display, etc., but nothing that showed me the whole enchilada.

Step 1: Matrix Body

The body is made of a plywood board (210 mm x 210 mm), a lattice of card cut from 800 GSM card, white paint and white glue. I've also made a frame around the matrix from 10 mm pine strips (200 x 10 mm).

First, I created an 8 x 8 table in MS-Word and set the Row and Column height/width to 2.5 cm and then printed it out on my printer. I cut around the printed table and glued it onto a sheet of 6 mm plywood. When the glue was dry, I cut out the grid using a jigsaw.

The second stage was to mark the center of each cell and drill a 5 mm hole in the middle of each.

The lattice was made by cutting 20 mm x 200 mm strips of card from the 800 GSM stock and then cutting 1 mm slots into the strips so that I could slot the strips together to make a grid, much in the same way that you find wine bottles separated in cardboard cartons. The slots were cut 1 mm wide so that they would allow the opposite strip to fit easily. The lattice was glued together and another 4 x 201 mm pieces were cut to provide a border (with a 1 mm overlap).

After the glue had set, I glued the lattice to the plywood, using the printed grid as a guide for the lattice.

I laid the matrix down upside down on my workbench and weighted it down with a number of thick text books so that the glued and cured matrix would be very even.

I found that the matrix could easily support 10 kg of books, so I guess that it's pretty strong.

Where the slots were a little loose and allowed light to get from one cell into the neighboring cell, I cut a small piece of paper and glued it over the gap on both sides. This meant that the amount of light that can get through is minimized (but not eliminated).

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Bio: I have been working in IT since the mid 1980's. Most of that has been database and application development. I've been working on ... More »
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