Definition 1 of 2
Definition
A control or signal arrangement in which a portion of the output is fed back into the input in a way that reinforces and amplifies the original signal. In electronics, positive feedback is used in oscillators to sustain a continuous output. Uncontrolled positive feedback in a control system causes the output to grow until it reaches a limit or the system becomes unstable.
Plain English
When part of a system's output is sent back to its input in a way that adds to and strengthens the signal, making the effect grow rather than settle.
Context Anchor
Seen in discussions of aircraft systems, autopilots, electrical circuits, and stability problems.
Derivation
From Latin positivus meaning 'placed' or 'affirmative,' and 'feedback,' meaning a return of output to input. 'Positive' here means the returned signal adds to the input rather than opposes it — not that the result is good or desirable.
Why Pilots Care
Positive feedback can produce runaway oscillations or loss of control in flight systems, requiring prompt pilot override.
Analogy
It is like a microphone placed too close to a speaker: a small sound is picked up, sent back through the speaker, picked up again, and quickly grows into a loud squeal.
Intuition Check
Do not read “positive” as “good.” In this term, “positive” means the feedback adds to the change and makes it larger.
Example Sentence 1
The radio's oscillator circuit relies on positive feedback to generate a steady signal.
Example Sentence 2
Technicians traced the erratic heading hold to positive feedback in the rudder channel.