Hello, I want to make auto gain amplifier. However, I cannot find anything that works. I will take a signal from a microphone and then it will be amplified but the gain must be autogain. For example, when I give 1m volts peak i will obtain 1 Volt peak and when I 2m Volts peak again I should obtain nearly 1 Volt peak. And my project must be compelety with analog components. Can you suggest me a way or is there any sample circuits that works?

 

I think, you are looking for an AGC circuit (AGC amplifier)?
AGC=Automatic Gain Control.
Perhaps you will find something via Google ("AGC circuit") ?

 

I think, you are looking for an AGC circuit (AGC amplifier)?
AGC=Automatic Gain Control.
Perhaps you will find something via Google ("AGC circuit") ?

Actually I tried both of them but none of the circuits work for my needs. Thank you.

 

Actually I tried both of them but none of the circuits work for my needs. Thank you.

So - you have some specific needs?
In most cases, such anAGC amplifier is "linear-in-dB".
It has a control input which receives the feedback signal.
Do you need a block diagram?

 

Maybe this will help: Synthesizing an Audio AGC Circuit

 

Here's the LTspice simulation of an AGC circuit using a JFET and an op amp.
It responds to the average value of the signal so it's less affected by short, high intensity sounds as a peak responder would be.

 

AGC using OTA a classic -

http://www.synthdiy.com/files/2002/LM13600.pdf page 10

Also VCR (Voltage Controlled R) possibilities.


Regards, Dana.