Re: Microphone Sensitivity
First,I apologize for my terrible handwriting.It is not 1ms,it is 1M5 ; i.e. 1.5 MOhms.This value is approximate since I don't know the exact H21(beta) ot the transistor.Rb also depends on the microphone V-A curve.You'll have to find the value experimentally.
On the left side of the picture (input) is the microphone itself;the right side (output) is connected to the microphone connector of the sound card.It is stereo and has three wires one of which is ground.
It is possible that your microphone has a stereo connector,too.Don't worry,just short-circuit the active ends.They are most probably connected together anyway.
What I described applies to a relatively modern sound card (after 2000).I don't know if there used to exist cards of different types which have a different way to connect to a microphone.
All soundcards that I have seen have a stereo microphone input.However only the one active connector is really input; the other supplies +5V through 5kohms resistor to the electrete microphone.My idea was to use this feature and power up an additional amplifier.
!!!!! By the way,the input capacitor is 47nF,not 47uF.It is important to place the right one .
That's all for now ; don't worry to ask me again if I did not explain something.