StrobeTuner is an Arduino library for creating simple "strobe" guitar tuners.

https://github.com/chazomaticus/strobetuner

A while back I bought a little "strobe" tuner (see MusiciansFriend or Amazon) for my guitar. I use "strobe" in quotes because it turns out it's just a couple of LEDs on a variable timer. I've been learning my way around an Arduino, and thought I could make my own "strobe" tuner for pretty cheap, with the added benefit of being able to tune to any note I want.

Hence, StrobeTuner, an Arduino library for creating your own "strobe" tuner out of two LEDs and a resistor. See StrobeTuner.h for the example circuit, or see the image below. You might want to mount the components somewhere you can easily shine the LEDs on your guitar strings.

When I compared my implementation to the real "strobe" tuner, I noticed my version was slightly off. I don't see anything in the code that would cause the discrepancy, so I'm chalking it up to error in the Arduino's oscillator frequency. We're talking a around tenth of a percent slower than it should be. In the example, you can see I just multiply the note's period by 99.9%, which fixes the error on my Arduino.

It's also possible I just don't understand precise timing on the Arduino yet, and my code is rife with bugs. Your mileage may vary.

To install, put this code in a subdirectory of your Arduino sketchbook's libraries directory. See http://arduino.cc/en/Guide/Libraries for details.

Enjoy!