1. Cardboard Cutout

The Word Clock display is made up of an array of 13x13 LEDs that are mounted on a cardboard cutout that fits snuggly into the front of the Clock Case. It is best to use cardboard because it wont melt when you are soldering wires to the LEDs and its easy to work with.

Use the dimensions of the aperture of the Clock case to trace out the required shape and cut out a piece of 3-4mm thick cardboard.

2. LED Grid

Use the enclosed template file to create 11cm x11cm grid to position the LEDs on the display board. Enclosed is a template that can be modified and printed out then glued onto the cardboard.

I used a free version of a draw program called LibreOffice Draw that you can download from here. LibreOffice The files can be modifed and resized using this tool. You can use the export feature to get different formats.

3. Mount the LEDs

In the example I used high intensity white surface mounted LEDs that I cut from a 3v LED strip. My advice is just use high intensity 3v Strip LEDs as they are easier to mount and don't require as much soldering.

(I recently did try 5mm LEDs and had a high LED failure rate and a lot of frustration with soldering so went back to strip LEDs)

The key point is that you join the Anode (+ve) side of each LED in each vertical column together on one side of the cardboard. Then pass the Cathode (-ve) through to the other side of the cardboard through a hole and join each row together on that side.

What you end up with is 13 Anode strips on the LED side vertically and 13 Cathode strips on the other side horizontally.

These are then connected to the Arduino Shield from the previous step as per the circuit diagram.

4. Test the LEDs

I recommend at this point testing all of the LEDs to ensure that there are no faulty devices/connections. To test use a 5v-9v DC power source and place a 2.2K ohm resister in line with the positive supply. Its important to do this to protect the LED from over current and burn out.

Connect the negative terminal to the LED Cathode and the positive terminal via the resister to the LED Anode of to test out. (Note ensure the Arduino Board is not connected when you do this). Make sure all the LEDs function and operate at the same brightness.