I forgot about the pictures.
I made two pictures with the mic and what i did with it. I put them
online here :

http://electronica.asm.ro/electret/


OL> Dumitru Stama wrote:
>> I am trying to implement an aquisition system for a voice recording
>> project and i decided to go ahead using the attached schematics.
>> It is from a project found on the internet

OL> Looks like you got about what you paid for it.  This circuit only has a gain
OL> of 500 if the mic has 0 output impedence, 250 at 500ohms, and it goes down
OL> from there.  I haven't used an electret microphone before, but for most
OL> microphones that is way too little.

OL> I also don't like how the stages are DC coupled.  This will multiply the DC
OL> offset of the first stage by 100.  That may be OK in this case since the
OL> gain is so low.  If you increase gain the output offset will also increase.


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OL> consultant in 2004 program year.  http://www.embedinc.com/products

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