1. Cardboard Cutout

The Sound Loactor display is made up of an array of 8x8 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 2-4mm thick cardboard.

2. LED Grid

Use the enclosed template file to create 8cm x 8cm grid to position the LEDs on the display board. I found that a spreadsheet programme like LibreOffice Calc is quite useful for getting accurate grids for printing. 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 that you can download from here. LibreOffice The files can be modified 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. The key point is that you join the Cathode (-ve) side of each LED in each horizontal row together on one side of the cardboard. Then pass the anode (+ve) through to the other side of the cardboard through a hole and join each column together on that side. What you end up with is 8 Cathode strips on one side horizontally and 8 Anode strips on the other side vertically.

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.