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

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

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


******************************************************************
Embed Inc, Littleton Massachusetts, (978) 742-9014.  #1 PIC
consultant in 2004 program year.  http://www.embedinc.com/products
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist