building a microphone that will spit out 0-5v

Forum 2005-2010 (read only) Hardware Interfacing
1

Hey You Guys (in the voice of Sloth from The Goonies),

So I need to build, as cheaply as possible, a small microphone which will spit out 0-5v to go into an analog input. The quality of the mic and its sound isn't important since I'm just trying to get amplitude (volume/decibel) values. If I can get all the necessary parts for under or around $5, that would be great. (I need to build 10 of these things, so keeping the costs down is important.)

I've been working with a couple RadioShack mic elements (don't have the parts numbers, but they're a 2-pin and a 3-pin condenser element, respectively), but I don't really know how to properly wire them, as I'm getting nonsense from them in the serial monitor, so I'm clearly doing something wrong. I've been getting some constant value, not a fluctuating one, although I suppose this could be because the code I'm using to interpret the signal coming in off the mic could be wrong. I'd imagine I'm going to need an "abs" value, as mics are bipolar (running from negative X to positive X), but even after including the "abs" method selector, I'm still geting gibberish.

HELP! If anyone has a simple schematic or wiring description/protocol for such a mic (condensers are probably overkill; a dynamic or electret should be fine, unless the condenser is easier and cheaper), I'd really appreciate you posting it up here, as well as a parts list. I'd imagine I can get all this stuff from either Jameco or DigiKey, but I still need to know which parts I need.

Also, will I need any special/uncommon code to properly read this analog data? If so, please tip me off to what it would be.

Thanks again, and I apologize for the noobishness. The tips I've been getting from these forums have been indispensible so far, and I really appreciate all of your help.

Jake

2

hi

the mic already puts out a varying voltage, so the task is just to bring it into the 0-5V range. You need an amplifier that is powered from 5V, like this one. Should be buildable for under 2$ a channel.
Here also is a nice diagram showing how to wire the two-pin variety of electret mics into your amplifier. Power is supplied through a resistor, and the signal is extracted from that by the capacitor.
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