Author Topic: Need advice for op-Amp for Arduino Mega/Duemilanove  (Read 4548 times)

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DividedSky

Need advice for op-Amp for Arduino Mega/Duemilanove
« on: August 13, 2010, 05:05:26 PM »
Howdy Folks,

This is my first post on this website, so please forgive me if I've put this in the wrong area.

I need a little help building an op-amp for a mini-grant project I received from my University. I'm building a simple guitar tuner that will use an Arduino Mega to detect pitch and represent each of the 12 notes as a color in the chromatic light spectrum (using a http://thingm.com/products/blinkm-maxm.html). The arduino will play a few random notes with PWM while flashing and then you try and play the same pattern (just like Simon).

http://www.tonychai.com/guitar.html <- This guy was kind enough to post his code for a guitar tuner project he built with an Arduino. I can't figure out what IC he used for his op-amp circuit... I've already modified his code to do what I need, but I can't get the arduino to read my signal. 

Here's his schematic:

I can't find an ECG891N anywhere.

I'm a Computer Science major and some of this EE stuff is over my head. I have it working using an FFT via Processing's Minim library and serial communication, but I want this to be a standalone project.

Please help!!!

Thanks,

DividedSky

RonaldB

Re: Need advice for op-Amp for Arduino Mega/Duemilanove
« Reply #1 on: August 14, 2010, 01:39:05 PM »
I think a simple opamp will do. Something like a TL071 or something.

best of luck
RONALDB

DividedSky

Re: Need advice for op-Amp for Arduino Mega/Duemilanove
« Reply #2 on: August 16, 2010, 04:12:50 PM »
Thanks RonaldB I'll give it a shot! I think i have to boost the voltage to 5V so the arduino can read it.

auximines

Re: Need advice for op-Amp for Arduino Mega/Duemilanove
« Reply #3 on: November 10, 2010, 07:13:24 PM »
Thanks RonaldB I'll give it a shot! I think i have to boost the voltage to 5V so the arduino can read it.

I was working on something similar and found this schematic and the website you mentioned.  The boost circuit you posted is designed to increase the voltage from the guitar but I found that I needed a 0.1 uF filter on the input and output to get decent readings and a resistor to ground befor the output in order to zero the readings when the strings weren't vibrating.

Hope this helps.