I want to circuit bend a digital guitar tuner and use my arduino to send midi data to a synthesizer. The tuner I want to use displays the note name in a little digital display and an led that goes on when the input frequency matches the note in the display. This is my first microcontroller project. I am a Pure Data user, I have studied the arduino tutorials and can understand some of the basic arduino code. I see from my research that sending midi data out through the serial port is quite well documented. I think I can cough up the math to convert frequency to midi or any other conversion that is necessary. Can anyone help me figure out how to get a useable signal from the guitar tuner to my analog inputs?
I have a similar tuner for a violin, and it's pretty well potted so you can't get at the guts easily. The obviously exposed stuff would be the flat, good, sharp LEDs, the core crystal, the speaker, microphone, line in, and buttons. The LCD has a very specialized display including a 7-segment area for the note name. There doesn't seem to be any exposed "test probe" points that might give you a frequency counter or reference voltage or anything.
To read a microphone signal on an Arduino analog pin, you'll need an amplifier, not a voltage step-down circuit. The Arduino needs 0-5V on the analog input pins, to read out 0-1023 in the code. So you'd need to boost the microphone's signal (a few millivolts) with, say, an op-amp.
Anachrocomputer is correct, the mic outputs a very small voltage. But, it's worse than that. It outputs AC. The diaphragm vibrates both up and down. Just look at how sound waves on a scope go both above and below the zero line. The arduino wants 0 - 5V but if you use just a normal op-amp you'd be liable to get -5 - 5V. What you need is to use an amp to amplify the signal up to a maximum swing of 5V and bias it so that 2.5V is the new zero line that the signal crosses. You can do this with amplifiers but you need to be aware of it and plan for it.
hmm, sh&%. I always thought it was larger voltage spikes with negligible amps that came out of a mic (hence the term amp-lifier). When I was 9, I plugged a guitar into my dad's tape player, pressed record and pause and used the tape monitor function to amplify my bad power chords. I always thought it was the volts that fried that thing. I'll go back to my old physics textbooks and review. Maybe we should re-term it a voltifier.
I digress.
Someone must have attempted this before.
