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Variable gain amplifier

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T

treez

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Hello,
We need a variable gain amplifier. But very simple. The gain should be variable with a control voltage. Non-inverting.
Do you know of one.
All the Analog devices ones have way more features than we would like

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We have a half sine control voltage which we wish to gradually vary the magnitude of. (ie not different discrete switchable gain levels)
 
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Many possible solutions, different by linearity, noise and drift, bandwidth, accuracy and repeatability. Some specs needed.
 

its just the 100Hz half sine reference to a error amplifier of a pfc stage....we need to change its magnitude slowly. from 2v peak to 0v peak
 

A light-dependent resistor (usually Cadmium-sulfide cell) is an option.

A jfet varies its gain as you vary bias voltage. These are less readily available than they used to be.

Also consider a magnetic amplifier (made from a transformer). Gain is altered by running a DC voltage in one winding, while running the signal through the other winding.
 

For these types of uses, a CA3080 would fit the bill. But my understanding is that it is nowadays obsolete.
 

Hi,

Now we know:
* 100Hz half sine
* 2V peak --> 0V peak

Any trimmer, any pot, any EEpot should do.

Klaus
 

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