Automatic Gain Control

[Frosty_47]

Hello,

I am looking to built an op-amp based automatic gain control for low frequency sine wave signals (1Khz-10Khz). The circuit must detect varying amplitudes and stabilize them to a set value (say 10Vpp). Example: Input = 1Vpp sine wave of 1Khz, Output = must be 1Khz sine wave at 10Vpp. This circuit needs to manage it without user input. Please help, I have looked through all the books in my library but cannot find an answer.

 

[Dx3]

You need a "compander"...compresor/expander
Signetics usta make one. Now they don't.
Search for compander.

 

[crutschow]

One of **broken link removed** may work for you.

Another technique is to use an analog multiplier for gain control.

The gain control is typically done by rectifying and filtering the output voltage to generate the gain control voltage.

 

[Frosty_47]

I like the analog multiplier idea however that particular one has 4 inputs and it's output is (X1-X2)(Y1-Y2)/10V.
How can I use it for only two inputs?

-Thanks

 

[Frosty_47]

Bahaha I am such an idiot!
I just realized that I can turn the AD633 into a two signal multiplier (X*Y/10V) simply by grounding X2 and Y2.....

Sorry for the stupid post above and thanks for your help, I can now move on with my project....