2 July 2011

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.

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.

14 June 2011

Now on Flickr

Since some of my projects result in photos, I decided to create a Flickr account to host them in more detail than is possible in the blog.

You can find them on


I recently took a few new  pictures with milk on a blue plate, which can also be found there. Here is an example.

11 June 2011

A Simple Electronics Project for Kids

Project Features
  • Simple
  • Cheap
  • Doesn't take long
  • Can be done by children (with a little help)
When I was working on one of my projects recently, my 8-year-old son came along and wanted to "help me". I was working on something really complicated and there was no way I would let him meddle with it.

On the other hand I wanted to take the opportunity to show him that electronics can be fun. So I decided to build a small 9-Volt torch light with him.

28 March 2011

Low-Cost High-Speed Photography - Part 3

Find this and other photos HERE.

The Final Hardware

And here is the final part of the entry, starting with the schematic that I finally used. The core is the same as before. But now there is a linear voltage regulator for the controller. Also shown here is the serial interface and most importantly, the sensor circuit.

19 March 2011

Low-Cost High-Speed Photography - Part 2

The New LED

The Cree XM-L T6 looked very much like the no-name LED that I had used previously. Being impatient, I did not modify the driver circuit immediately, which meant that the current would be about 1.5 Amps and the resulting power would be about 4.5 W. This should yield at least 5 times the brightness as compared to the no-name LED.

And this is the very first shot that I got with that LED:

Not too bad, I think. Click on the picture to get more detail.

17 March 2011

Low-Cost High-Speed Photography - Part 1

Find this and other photos HERE.
Project Features
  • Produces white light flashes for high-speed photography and multiple exposures
  • High flexibility / reconfigurability (menu controlled)
  • Low cost (no flash unit needed, mostly cheap parts)
  • Simple hardware
  • No recharging time as for conventional flash lights
Some of the ideas I have take years until I actually put them into practice - be it because there are other, more interesting things to do, be it because I can't find some of the parts or be it because I can't solve some of the problems involved with it. The LED stroboscope was one such project. I had no idea whether a power LED would be bright enough for what I planned. And power LEDs were just too expensive for trying.

The basic idea was to use bright white LEDs to build a flash unit for photography. This could be used to take high-speed photographs (just generate one short flash when triggered by a sensor) or to take multiple exposures by generating a train of flashes. In principle, it is a very simple project, and a microcontroller is almost an overkill. It can probably be done with an NE555. The one advantage a controller has is that it is very flexible. So you can change timings with little effort.