The process of taking a fraction of a system's output voltage or current and applying it back to the input. Negative feedback subtracts from the input to stabilize gain, increase bandwidth, and reduce distortion in amplifiers. Positive feedback adds to the input, pushing the circuit into oscillation or creating a latching state. In live audio, unintended positive feedback creates a loud, continuous squeal when a microphone picks up the speaker output.
Heard on the job
Add a 10-kiloohm resistor in the feedback loop to set the op-amp's gain to exactly two.