Bar-graph music display using 20 linear nixie tubes
This is an undocumented ill-fated project. It's really beautiful, but I failed somewhere in the circuit design and it burned several times. Do not reuse this circuit blindly. At the time LPC1769 seemed a good chip for the design, but I would not recommend using it either.
Software part is good and hopefully it can be useful. Instead of typical FFT analyzer, I'm using a set of biquad bandpass filters. This allows for extremely fast response time.
Here's a video of Bargraphnik dancing to the tune by Andy Statman: http://www.youtube.com/watch?v=N1V3hcfybmE