Editing Gyrator (section)

==== Applications ====

The primary application for a gyrator is to reduce the size and cost of a system by removing the need for bulky, heavy and expensive inductors. For example, [[RLC circuit|RLC]] bandpass filter characteristics can be realized with capacitors, resistors and operational amplifiers without using inductors. Thus [[graphic equalizer]]s can be achieved with capacitors, resistors and operational amplifiers without using inductors because of the invention of the gyrator.

Gyrator circuits are extensively used in telephony devices that connect to a [[Plain old telephone service|POTS]] system. This has allowed telephones to be much smaller, as the gyrator circuit carries the [[Direct current|DC]] part of the line loop current, allowing the transformer carrying the AC voice signal to be much smaller due to the elimination of DC current through it.<ref>
Joe Randolph.
[http://www.randolph-telecom.com/articles/AN-5,%20Transformer-based%20phone%20line%20interfaces%20_DAA,%20FXO_.pdf AN-5: "Transformer-based phone line interfaces (DAA, FXO)"].
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Gyrators are used in most DAAs ([[data access arrangement]]s).<ref>
[http://www.daycounter.com/Circuits/Gyrator/Gyrator.phtml "Gyrator - DC Holding Circuit"]
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Circuitry in telephone exchanges has also been affected with gyrators being used in [[line card]]s. Gyrators are also widely used in [[hi-fi]] for graphic equalizers, [[parametric equalization|parametric equalizers]], discrete [[Bandstop filter|bandstop]] and bandpass filters such as [[Rumble measurement|rumble filters]]), and [[Pilot signal|FM pilot tone]] filters.

There are many applications where it is not possible to use a gyrator to replace an inductor:
* [[High voltage]] systems utilizing flyback (beyond working voltage of transistors/amplifiers)
* RF systems commonly use real inductors as they are quite small at these frequencies and integrated circuits to build an active gyrator are either expensive or non-existent.  However, passive gyrators are possible.
* Power conversion, where a coil is used as energy storage.