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Topic: Audio Input from Microphone (Read 3239 times) previous topic - next topic


I'm attempting to build a audio spectrum analyzer (using addressable RGB LEDs).  I'm probably OK at the programming side and hopefully doing the FFTs on the arduino but it's the electronics I'm new to.

The hard part is looking like getting audio in from a microphone.

I started out trying to follow the Instructable at http://www.instructables.com/id/Arduino-Audio-Input/ but it uses two 9v batteries as power, and I'd like to use the standard 5v power.  (This could be from an external power regulator - not the ardunio  - so I can power enough LEDs).

This - http://proto-pic.co.uk/breakout-board-for-electret-microphone/ - component would probably be ideal but it has a fixed 100x gain, whereas I'd like an adjustable gain, as the comment on that page explains.

Finally I found this - http://learning-arduino.tumblr.com/post/12046833573/automatic-beat-detector .  Does that look like it would do what I need?  I'm wary because (s)he says "Overall, I'm not satisfied with the result" but it's all I've been able to find.

I'm starting to think I might have bitten a bit too much off for my first arduinio project!

Thanks :)


I'd not worry about fixed gain mic, you always can re-scale / re-map input signal to your wish in software. You even can implement AGC (automatic Gain Control) and keep led's bliking up and down with variable input loudness.
An example in a link in signature.


But if the input is > 5V won't the arduio clip it?

I like the look of that breakout board in your link.  Might give that a go, turns out I can even get it from my local h/w store :)


Place I get a board: http://www.abra-electronics.com/products/BRD125-Printed-Circuit-Board%252d3-3%7B47%7D4%22x5-1%7B47%7D2%22.html
Used already in several  projects, it has routed power lines, very convenient with multiple IC design. 
Regarding clipping, mic linked above receiving power from arduino 5V (VCC), so if clipping happened it would be on mic board, before it reach arduino input.
100x not really big gain, and if your sound level too high there is no way to avoid clipping, as first amplification stage - unregulated inside mic itself. Use Styrofoam ear protection  :)



I got that BOB board working fine but only after I wired it into a 3.3V VCC off my arduino board (although the datasheet suggests 5V as better). You will probably need to regulate the voltage first.

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