Snazzy light show, but bye bye fingerprints!
I was so enthralled in my recent review of the Arduino Uno starter kit from RS Components that I started scouring the net for other interesting projects that I could try.
That’s when I stumbled across this post by James Bruce which gave a fantastic step by step guide on how to make an LED cube.
Not only does James show you exactly what you need to do, but he also takes time to demonstrate the electronic principals behind it in some depth.
I found it a great read, so decided to have a crack at it myself, going one step further and fabricating it into a nice case so that it can be used as a display piece.
The LED Cube
It would be pointless repeating everything that James wrote in his original walkthrough, so for a step by step guide I’d encourage you to check out his original post on the link above.
What I’ll show you here is how I took his design on a step into a complete unit.
Lets start with a straight shot of the cube.
As you can see, I’ve opted to enclose the Arduino board and the main circuit board inside a black plastic case.
The original plan was to make a black acrylic container for the cube from sheet acrylic. However, I was dubious of my own abilities when it came to cutting the acrylic sheet neatly by hand, so in the end I opted for a pre-formed plastic case that I picked up in a local electronic store.
The cord that you see protruding from the back of the case is the USB cable that’s used to program and power the Arduino board. I managed to cute a reasonable size hole in the back of the case for the USB connector to poke through.
If I were to make another of these (and believe me, people have asked) then I would also cut a hole for the circular power jack to poke through. That way people have the option of using a USB power supply or a 9-12v power supply. It’d also be possible to mount a 9V battery inside the case and power directly off that, but I digress.
Inside the case you’ll find the Arduino Uno board, stuck to the bottom of the case using silicone adhesive. The jumper leads are then soldered onto machine wire, which is then soldered onto the prototyping board which makes up the rest of the circuit.
There was really no reason for doing this other than I didn’t have long enough jumper leads to hand. I wanted to make sure that I left myself enough room to be able to connect everything up without the short leads causing the lid to be an obstruction.
In truth, having longer leads would have been a real help when it came to connecting the different columns to the Arduino inputs, as it stands I had to chase each wire as I didn’t have any sort of colour code for the PCB.
I could have also used a ribbon cable which would have been a lot neater, but a little trickier to solder onto the prototyping board.
The initial plan was to solder the connecting wires to the top of the board, as you’re supposed to.
The problem is, when I did that, I couldn’t then see well enough to push the LED legs through the top of the plastic casing and then through the specific holes on the circuit board. That was, by a long way, the most difficult part of the build.
In the end, I had to resort to connecting the wires to the underside of the board. In this case, it was a must, but generally it’s a bad idea.
Once all the wires were soldered on and connected to jumper cables, it was just a case of connecting them to the Arduino board and using more silicone adhesive to hold them in place.
This type of adhesive is great because it’s completely inert. It won’t affect any components on the Arduino board, nor will it interfere with the circuitry in any way. Also, although it does a fantastic job of holding things in place, it can be peeled off really easily if you ever need to change anything.
In this project it was the ideal solution to keep the Arduino board in place inside the case, and to keep the jumper cables securely connected to the Arduino.
The prototyping board, on the other hand, is held in place by the solder joints of the LED legs. Trust me, it’s not going anywhere.