Hello, I searched this forum and other internet sources for a circuit to interface a electret mic with my arduino. I found the following and bought the components, but I cant get it to work, when I turn the trim pot the analog value goes from 600 to 1000 without any response to sound. Can anyone see an error in the circuit?
Thanks
//Chrille
I can't see anything wrong with it, I've used similar circuits in the past. I'd have used two resistors instead of the pot to bias the non-inverting input. There are much better devices than the ancient 741, BTW. Try removing the diode and the capacitor on the output, and setting the bias to 2.5V.
I'm using a single transistor amplifier for a similar application with a dsPIC.
http://www.national.com/mpf/LM/LM741.html#Parametrics
LM741 the Power Supply Min is 10 Volt
You need to try other Op Amp that working with lower voltage like LM358
Ohh, ok, thanks for the quick answers. 
Edit:
Could it possible work if I use a power supply from a computer and use the 5v to the arduino and the 12v rail to power the amp?
Anyone?
fwiw using a PC PSU would be fine in theory (can't comment on more than that).
If you just want a go/no-go sound detector (not measured... just triggered if a threshold is broken) then I'd recommend this guy;
http://www.parallax.com/Store/Sensors/AllSensors/tabid/760/CategoryID/46/List/0/SortField/0/catpageindex/4/Level/a/ProductID/614/Default.aspx
I've personally used it with my Arduino and it fits that bill perfectly. Read the features and see if it fits your needs. Super easy, super small and no building your own (over sized) circuit, but it wont measure sound levels.