While [Vinod] says he’s not an expert in this sort of thing, we really like his audio spectrum analyzer build from a simple microcontroller and LCD display.
It is a well-studied fact that every audio waveform – a recording of your voice, for instance – is just the sum of many, many sine waves. These sine waves can be plucked out using Fourier analysis, using a Discrete Fourier transform. This is the principle that spectrum analyzers operate under; [Vinod] wrote a bit of code using DFT to take apart audio captured from a microphone and output their frequency on an LCD display.
To output the spectrum on his LCD, [Vinod] stacked horizontal bars up into 8 custom characters in his display. Like [Vinod]’s previous audio on an ATMega32 experiment, an LM324 amplifier is connected to the ATMega through an analog pin. [Vinod] has a very clever build on his hands with his spectrum analyzer, and a great answer to the perennial ‘how do I build a guitar tuner’ questions we’re constantly asked.
After the break, you can see [Vinod]’s spectrum analyzer in action. Be forewarned; you may want to turn down the volume.