Guitar is one of the most favourite music instrument. To get great sound you need to tune it first. There are many guitar tuner based on electronic circuit that can be use to tune guitar easily. One of them is Digital Guitar Tuner using microcontroller AVR Atmel 2323 created by Jesper.
"This microcontroller project is a simple, but accurate for Digital Guitar Tuner. It samples the input, which can be directly from the mics of an electric guitar, or from a microphone, it you're using an acoustic guitar. The circuit also can be used for tuning other instruments."The samples are then checked against stored values for the strings, and the two LED's will show the tuning status - "Too Low", "Too High" or "In Tune" when both LED's are lit. The tuner will automatically switch between the six strings. The circuit is pretty simple. A small transistor amp pumps up the input signal to something the AVR can see on it's input pin. The other two I/O pins are used for driving the LED's. The input sensivity is around 50-60 mV. This gives a 2-3 V swing on the input pin, enough for the 2323 to read this as high and low levels.
If you interest to build this project, you can download the document, source code, schematic here (zip file)
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