Editing Gyrator (section)

===Magnetic circuit analogy===
{{main|Gyrator–capacitor model}}

In the two-gyrator [[equivalent circuit]] for a transformer, described above, the gyrators may be identified with the transformer windings, and the loop connecting the gyrators with the transformer magnetic core. The electric current around the loop then corresponds to the rate-of-change of magnetic flux through the core, and the [[electromotive force]] (EMF) in the loop due to each gyrator corresponds to the [[magnetomotive force]] (MMF) in the core due to each winding.

The gyration resistances are in the same ratio as the winding turn-counts, but collectively of no particular magnitude. So, choosing an arbitrary conversion factor of <math>r</math> ohms per turn, a loop EMF <math>V</math> is related to a core MMF <math>\mathcal{F}</math> by

: <math>V = r \mathcal{F},</math>

and the loop current <math>I</math> is related to the core flux-rate <math>\dot{\Phi}</math> by

: <math>I = \frac{1}{r} \frac{\partial}{\partial t} \Phi.</math>

The core of a real, non-ideal, transformer has finite [[permeance]] <math>\mathcal{P}</math> (non-zero [[reluctance]] <math>\mathcal{R}</math>), such that the flux and total MMF satisfy

: <math>\Phi = \frac{\mathcal{F}}{\mathcal{R}} = \mathcal{P} \mathcal{F},</math>

which means that in the gyrator loop

: <math>I = \frac{\mathcal{P}}{r^2} \frac{\partial}{\partial t} V</math>

corresponding to the introduction of a series capacitor

: <math>C = \frac{1}{r^2} \mathcal{P}</math>

in the loop. This is Buntenbach's capacitance–permeance analogy, or the [[gyrator–capacitor model]] of magnetic circuits.