Here is a prototype color graphical EQ. It uses acrylic tubes so that the light moves up the tube as it gets brighter.
This was created using the 7 band eq chip and 7 22pixel lights from bliptronics.com. The tubes are acrylic tubes from stir sticks that were sanded to created frosted diffusion. On the top there is a hot glue stick to keep it steady. Holes in a butterflied PVC pipe hold the tubes and black felt covers the PVC.
Do you vary the height of the light by fading the LED's?
Yes -I pull the value from each band and convert from 0 to 1023 to 0 to 255. Then convert HSV to RGB and set a Hue for the band and the value as the above computed value and the saturation at 100%.
I am using the RGBCommonLED library / class to do the HSV to RGB conversion.
The code is a bit harder and I have a huge complex application, too much to post here as an example. That said, I am using almost none of the real brains in the app for this. I may be able to provide some slimmed down, basic code for this if requested.
do you have some pictures of the construction?
I do not have any construction pictures yet, I'll shoot a few with my phone as post them.
Here is a quick video that shows the EQ in the light with a basic overview on how it was built. The RGB led is the type with a build in IC .. forgot to mention that part :) This could be done with standard RGBs .. just need some shift registers to run it.