Dear friends, what is C2 doing in the picture

[DF96]

The right value of capacitor can aid stability.

The wrong value of capacitor can cause instability.

 

[Pano]

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[qq91816]

Ignoring the effect of the big electrolytic capacitor, the amp has a DC gain of 1 (0dB) which essentially continues until the unknown reactance of unknown value of C2 equals the resistance in parallel with it. This will be the corner frequency of +3dB, an if you continue increasing frequency, the amp theoretically reaches infinite gain, only limited by the opamp ihnherent gain.

This is how the schematic works in few and simple words.

My English level is very poor, although it is not easy to understand, but I thank you very much for your patience.

 

[jan.didden]

Sorry, I may have doubts on this issue.

I was told that C2 is a "dominant pole compensati" capacitor and that it stabilizes the circuit？？

But you said it would lead to circuit instability
.

I'm sorry to disturb you.

It's not dominant pole, it does not cause a pole. It is very strange, might well lead to instability; in fact I believe it definitely causes instability, unless there is some weird load at the output we don't see that advances phase.

That is why I said before, if this is a diy schematic, all bets are off, meaning: it may work or it may totally f*uck it up. Diy-ers do weird things sometimes without understanding.
Then it oscillates and they praise the 'clean and detailed reproduction'. Go figure...

Jan

 

[qq91816]

It's not dominant pole, it does not cause a pole. It is very strange, might well lead to instability; in fact I believe it definitely causes instability, unless there is some weird load at the output we don't see that advances phase.

That is why I said before, if this is a diy schematic, all bets are off, meaning: it may work or it may totally f*uck it up. Diy-ers do weird things sometimes without understanding.
Then it oscillates and they praise the 'clean and detailed reproduction'. Go figure...

Jan

I see. Thank you.