A while back I purchased a funduino board and the corresponding 8 * 8 full colour LED pug in module. When I first powered it up it was pre-loaded with some demo which ran through a simple display, this was really cool I thought!! Then I found the “PLASMA” program and once I got it running was totally blown away! In a strange way I find it quite annoying that there are people out there so much cleverer than me!!!
Check out Lincomatic’s blog for information on the plasma display and Arduino library, this instructable is about the home made array and enclosure.
Anyway I really liked the plasma display and decided to scale it up. And also defuse the light so the individual LED’s were not visible. The result is a box which has a display area of 210mm square and is nice and bright.
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Step 1: Part One. the Original Circuit and Display
So the original Funduino board and LED matrix measures just 60 by 60mm and is fun to test on, once you have a FTDI cable made up you can experiment with the program and test out the display. The Colorduino Library written by Lincomatic allows you to set individual pixels or fill the whole screen with a set colour. Check out his blog for all the details.
Then I loaded the plasma display. This is very clever and generates very nice patterns and colours based on a calculation using sine. I won’t pretend to understand it, but it is very nice! When I was playing with this pattern I discovered placing a piece of paper over the LED’s makes the pattern better and lifting the paper away from the surface produces a flowing display eliminating all the individual LED’s. Check out the video for a visual definition!
Step 2: Part Two. the Correct LED’s and Perspex Sheet.
So having decided to scale up the display I needed to find some suitable LED’s I decided on 5mm defused LED’s but what is important is that they are common Anode or +. I ordered some from EBay which were a good price. (Be warned the Anode is normally the longest leg but the other 3 colours can be in different order depending on manufacturer.) Next I wanted a piece of frosted Perspex to defuse the light and I also found this on eBay (Acrylic Perspex Frosted Sheet). The size might seem a bit strange if you aren’t from the UK that’s because its A4 paper size which is 210mm by 297mm (3mm think). This sheet was then cut to 210mm square, which then gave me the dimensions for the box.
Step 3: Part Three Soldering Together
Once I had got the LED’s and Perspex sheet I then cut out and drilled the 3mm plywood to mount all the LED’s in, I worked out the distance of each LED by firstly subtracting 3mm for each edge then dividing the rest by 8 and then marking out half way between. Which put the LED’s 25mm apart. While I was cutting and drilling wood I also cut out a small section to use as a forming jig. Next I needed to decide how I was going to connect all the LED’s together, basically in each row of 8 all the reds need to be common as do all the greens and blue, then in each column all the anodes need communing, meaning you will have 8 red wires 8 blue wires and 8 green wires then I choose 8 orange wires for the anodes. I decided the best way to connect all the LED legs was to bend all the legs over at different heights then connect by soldering a piece of tinned wire across all the legs. You can see in the pictures how I did this using a 3mm drill to form a nice radius. I left the anodes straight up as these wires would run the other direction and would have to be over the other 3 wires.
Soldering LED’s isn’t hard but you should try to be very quick and avoid soldering near to the LED body. The tinned wire was stripped from single core wire then straightened by “twanging” in a vice.
Once all the LED’s were in place and soldered together I then added all the wires (32 in total) as shown in the photos, these were terminated to a piece of veriboard which has two strips of pins on the other side which mate
with the sockets on the funduino.
Step 4: Part Four the Enclosure.
I experimented with the frosted Perspex to find the optimum distance the Perspex had to be from the LED’s to eliminate the individual LED’s and I found that 8cm was perfect. So then I just measured the space required at the back for the wires and funduino board to sit above and came up with a total distance of 13cm. The sides were cut from 6mm ply and had a joint added to each end to help fit the sides together, I also decide that the LED plate would also be glued in to give the box strength. The Perspex sheet is a good fit but can be removed. A strip of 3mm ply was added to the front of the sides to allow the Perspex to sit in nicely at the required distance and a smaller piece of ply was added to align the led sheet in the correct place. Then the whole lot was glued and
held tightly together overnight using string.
The last bits to add to the box were sections of ply to sit a small 70mm square platform to screw the funduino on. And lastly I had to add a back to the box as the kids picked it up by the wires in the back and pulled some of the LED’s out!!
Step 5: Part Five the Video
It was really hard to get the video to work as it was flickering. So after a little online search I tried overlaying the video a few times and that has made it better. So the first section I’ve overlayed 4 times with each clip set to 25% and moved one frame. Then the original footage with and without the Perspex is shown.