Negative feedback.

[caps]

Id like to request any links that you may have that get into the nuts and bolts of feedback. Obviously, it reduces distortion, affects output impedance yada yada...

However, I cant find any information , for example, on exactly HOW distortion is reduced. A friend told me its because the output signal fed back to the input is 180 degress out of phase (I know this already), and the difference supposedly cancels out any distortion.

I got my doubts about how correct that is, and Id like to understand it more in depth than that anyhow. So, thanks ! :thumb:

 

[NewYorkDave]

This'll keep you busy for a while.

Harold Black's Patent--7MB(!) PDF

 

[caps]

Strike me pink Dave!!

errr., know of anything else about a little more intuitive and not quite so...

um...

damn brain straining ? :grin: :grin:

 

[NewYorkDave]

try this, then.

1Meg zipped PDF

Thanks to PRR for the hosting space.

 

[caps]

Thanks dave, Ill get to reading that tonight. In further searching I found thid

"The famous number 25 resistor returns the signal from the output of the amp to the input where it is compared with the input signal by subtraction. Any part of a signal that wasn't in the input is immediately corrected. By applying negative feedback the input stage has a reservoir of amplification it can draw from if anything goes wrong. "

Ok then, how exactly... is this difference actually "corrected" ? :shock:

 

[CJ]

http://vacuumbrain.com/The_Lab/TA/Tubes/nfb1.bmp

 

[Larrchild]

Because most amplifier stages are phase-inverting, it is important to count the number of inverting stages in a circuit, when adding a feedback loop.

For instance, the output signal used for feedback must go back to an earlier stage that will invert it. Then it is degenerative or inverse feedback.

The other way, it just howls.