The Charlie Cube Mark II: 4x4x4 - Update

Update
Build this simpler version instead!

Introduction
When I wrote my post on my charlieplexed LED cube, I never meant to publish build instructions. There are plenty of instructions around and a regular LED cube is much easier to make.

Instead, I wanted to show that it is possible to use charlieplexing for such a cube. And I wanted to share my thoughts on how I got there. So I never published schematics for the cube. Also, it is relatively difficult to draw a 3D electronic structure on a 2D schematic.

But quite a lot of people asked for a schematic. So in the end I just tried my best to draw it in an understandable way. I still think that for someone with some basic knowledge of electronics it is better to try to follow my explanations in the original post. But anyway, here it is.

The Charlie Cube Mark II: 4x4x4

Project Features

• Minimal hardware
• Wiring more complex than standard led cubes
• LED duty cycle 1/8

Update: There is a schematic and part list available here.
 
WARNING: Do not build this cube unless you know what you are doing! It uses minimal hardware but is difficult to understand.

There is a new design which is much easier to build with a very low part count.

Introduction

When I had finished my first charlieplexed LED cube (3x3x3) I wondered whether my next project should be a 4x4x4 cube. But at the time I thought it wasn't worth the effort. After all, I had just shown that a charlieplexed cube is possible and that it can be done with reasonable effort.

The 4x4x4 would of course have 64 LEDs, which would mean quite a lot of soldering. And since I would definitely want to use bright wide-angle LEDs, it wouldn't come cheap.

But the idea never really went away and when I found a good offer for a set of 100 suitable blue LEDs I simply couldn't resist.

The Micro POV

Electronics design in my opinion is the art of finding the best compromise. And this can be quite a complex art. There are many different and sometimes contradicting requirements to a project: Cost, time, space, weight, power, technology, market, availability of materials and tools, knowledge. This is why the all singing all dancing solution isn't always a good solution. Sometimes less is more. And I don't know why that is, but I have a special affection for minimalistic solutions.

I know, there are POV projects on the net in abundance. And most of them are some kind of propeller clock. There are a few really nice examples and I wanted to have one. I even started to build such a work of art and it was going to be really great with lots of colour and such. But very soon I gave up, because I just don't have the skills or equipment to build more complicated mechanical objects.

I realised that I had to reduce my expectations - a lot. And looking at various projects that I found on the net, I decided that maybe I should go for something really ... compact. And so the idea for a micro POV was born.

The name is of course a reference to the open source project MiniPOV by ladyada. But I wanted to go one step smaller - something to wear e.g. on the wrist. Of course that generates a few problems, which is just what made the whole thing the more interesting. Every component for this project needs special attention.