I had to work a little bit on an audio solution to get sound samples using a micro-controler. I based my design on an Internet really known circuit but I had to optimize it a little bit to be more efficient in terms of energy. This post is giving the result of my hack.
This circuit have 3 resistor and a transistor. I’m using a High gain transistor BC848C. The two resistors R2 and R3 are defining the Vout average around 1V.
R1 resistor is defining the microphone sensitivity depend of what you are expecting, in my case I do not need to be high sensitive, I choose 22K. This is the most consuming resistor so as much as possible choose a high value.
In this configuration the circuit is consuming 0.159mA.