I'm designing an arduino based guitar tuner based on the Arduino Uno R3. The way im planning the tuner is to build an analog preamp circuit that takes the input from the guitar, and converts the signal to the 0-5V range the analog inputs can handle
I've plugged my guitar into a scope (sadly I have no access to a spectrometer) to figure out the range of the frequency and voltage coming out from my guitar (Reverend Roundhouse), and for freq i got from about 82Hz - 1.6kHz (standard tuning only for now), and for voltage I got a huge variance from 300mV (maybe even lower sometimes) to about 1.8V max.
The problem I have figuring out is:
For freq, do I need a BPF of 82Hz - 1.6kHz or will just a LPF with a cut off of anything above 1.6kHz will do? I heard good things about ? 3-pole LPF at the output of the op-amp, what about for the input?
2)How do I figure out the gain i need for the preamp? Some circuits I looked at had a gain of 100-200 but wont that make the signal way too big, and wont the clipping for 0-5v cause a big loss of data?
I think this will work for you.
Don't this fancy of an ADC, I am going for audio recording.
Gain of 2, 2.5 will be plenty.
Only need open strings for tuning, yes? So filtering off above G on the upper E string would be plenty.
Try a simple RC lowpass filter to start, may be plenty.
1)While its true that I said I'm only gonna use it for standard tuning for now, I want it to be able to recognize any note on the fretboard from lowest E at 82Hz to highest, which is i think F at about 1.6kHz
Filter as you wish, some experimenting may be needed.
LM386 is used for playing sound thru a speaker. You're just driving an ADC input.
Guitar output is ~ +/-1V, like a microphone. ADC wants 2.5V +/-2.5Vmax.
