Editing Negative feedback (section)

== Examples ==
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* [[Thermostat#History|Mercury thermostats]] (circa 1600) using expansion and contraction of columns of mercury in response to temperature changes were used in negative feedback systems to control vents in furnaces, maintaining a steady internal temperature.
* In the [[Invisible hand|invisible hand of the market]] metaphor of economic theory (1776), reactions to price movements provide a feedback mechanism to match [[supply (economics)|supply]] and [[demand]].
* In [[centrifugal governor]]s (1788), negative feedback is used to maintain a near-constant speed of an engine, irrespective of the load or fuel-supply conditions.
* In a [[steering engine]] (1866), power assistance is applied to the rudder with a feedback loop, to maintain the direction set by the steersman.
* In [[servomechanism]]s, the [[speed]] or position of an output, as determined by a [[sensor]], is compared to a set value, and any error is reduced by negative feedback to the input.
* In [[Sound|audio]] [[amplifiers]], negative feedback flattens [[frequency response]], reduces [[distortion]], minimises the effect of manufacturing variations in component parameters, and compensates for changes in characteristics due to temperature change.
* In [[analog computing]], feedback around [[operational amplifiers]] is used to generate [[mathematical functions]] such as [[addition]], [[subtraction]], [[Integral|integration]], [[Derivative|differentiation]], [[logarithm]], and [[antilog]] functions.
* In [[Delta-sigma modulation|delta-sigma]] [[Analog-to-digital converter|analog-to-digital]] and [[digital-to-analog converters]] (particularly for high [[Sound quality|quality]] [[Audio engineer|audio]]), a negative feedback loop is used to repeatedly correct accumulated [[Quantization (signal processing)|quantization error]] during conversion.
* In a [[phase locked loop]] (1932), feedback is used to maintain a generated alternating [[waveform]] in a constant phase to a reference signal. In many implementations the generated waveform is the output, but when used as a [[demodulator]] in an [[FM broadcasting|FM]] radio receiver, the error feedback voltage serves as the demodulated output signal. If there is a [[frequency divider]] between the generated waveform and the phase comparator, the device acts as a [[frequency multiplier]].
* In [[organisms]], feedback enables various measures (e.g. body temperature, or [[blood sugar]] level) to be maintained within a desired range by [[homeostatic]] processes.
[[File:An example of a negative feedback loop is the process of increasing and decreasing glucose levels in out bloodstream.svg|thumb|]]