This is one that I’ve been excited about for a long time. When element14 asked me to put together a holiday special, I knew just what to do. This episode is the most technically complex so far; it covers non-inverting op-amp circuits, low-pass envelope detection filters, buffers, power management, and some clever programming. Because of the complexity of the project, fellow Cornell Engineer, Brian Schiffer (whom you might remember from this article where we were both featured) co-hosted this tutorial with me. The end result is pretty spectacular – a chain of 50 LEDs reacting dynamically to music. The twist, however, is that the chain propagates color information from the center, resulting in a temporal visualization of the music. The schematics, programs, and parts list are available for download below:
You can download the files associated with this episode here: Arduino Tutorial 14 Files
Source materials for all my arduino tutorials can be found in my github repository.
Update (9/2/2013): The code has been updated to reflect the new naming convention for the Adafruit LED Library.
Update (12/18/2012): Check out this system installed in a Car by Gyurma
Update (12/15/2012): The Adafruit Library has been updated, and will necessitate a small change to the code. Check out this comment thread for more info.
Update (12/2/2012): Some viewers have suggested improvements to this circuit that have worked well. If you’re having troubles with the circuit I presented, try out this circuit, by John Basila. Open Source Education wins again!
Update (6/9/2012): Check out this version made by Steved: http://youtu.be/iYxLQxpBTJ8