The concept of feedback refers to a system
where the output is connected to the input.
In this way the result influences the system itself.
Feedback is not limited to the electronics. You can find it
in many different systems in biology, chemistry, economics, etc.
Feedback circuits in the electronics return a part of the
output voltage back into the input via a coupling element...
Doing so two types of feedback can be distinguished...
Positive feedback :
the feedback voltage adds to the input voltage.
the feedback voltage subtracts from the input voltage.
Typical applications of feedback...