The bifilar pancake coil at its resonant frequency

[web000x]

Insert facepalm character here.   

I too was once dyslexic about that which reversed in a discharging coil.......

[citfta]

I never said the pancake coil was different.  If you would read the thread you would understand that the current DOES NOT reverse when a coil discharges.  That is true for any coil whether pancake, bilifer or any other configuration.  The idea of the current reversing apparently comes from people that get their education from YouTube.  I know of no one that has actually worked in electronics that believes the current reverses when a coil discharges.  The analogy of a flywheel holds true because the very definition of an inducter is that it resists any change in current flow just like a flywheel resists any change in rpm.  I am not going to rehash that whole thread in this post.  Read it and learn or ignore  it.  The choice of course is yours.  I was just offering you a source of experiments and observations to help you.

Respectfully,
Carroll

[Zephir]

the current DOES NOT reverse when a coil discharges.  That is true for any coil whether pancake, biflifar or any other configuration

OK - but at least the voltage of the opposite sign appears at the coil, once its magnetic field collapses. When the circuit is still closed, then the current of reversed polarity emerges in circuit. After all, it's visible easily in every circuit simulator, which traces current in circuit visually. Magnetic field is oriented - so that the charged coil remembers the direction of the original current, which created the flux.

You're pointing to situation, when the state of circuit also changes during collapse of circuit, for example during disconnecting the already energized coil from circuit - but this is special case. In steady state conditions of coil permanently connected into a circuit without active elements (diode, etc.) and similar exceptions the current following the collapse of magnetic field around coil will always have the opposite polarity, than the current, which created this field.

In hydrodynamic analogy the inductance of coil corresponds the behavior of hose with elastic walls. The introduction of current (i.e. hydrodynamic flow) leads to formation of  pressure drop due to inertia of fluid inside the hose. This pressure difference expands the hose a bit, so it accumulates the energy into itself. Once the pressure gets released at one end, then the accumulated fluid becomes ejected from hose in opposite direction. This model looks stupid, but it can illustrate even complex phenomena, like the skin-effect, which occurs in conductors during fast changes of flow direction. Because of inertia of fluid in the bulk of hose, the hose is forced to expand and collapse repeatedly so that the flow concentrates at the thin surface layer of hose only - and the interior of hose doesn't move.

[citfta]

https://www.quora.com/Why-does-the-current-direction-change-when-an-inductor-discharges

[Zephir]

I know of no one that has actually worked in electronics that believes the current reverses when a coil discharges.

Actually you're the very first person, who I know he believes in opposite... :-) For example the very existence of oscillations within resonance circuits illustrates, that the current reverses during collapse of magnetic field within coil (the capacitor and coils charge and discharge mutually during it). How did you got into the opposite?

Edit: From Quora link above given it seems, it's because of semantic fuzziness in application of the back electromotive force.  This force always acts in the opposite direction to the existing current, as its name ("BACK") implies. I.e. it decreases the existing current while the existing current still runs in the original direction. Once the original current doesn't change, then the inductor doesn't actually discharge, because it's magnetic field didn't collapse yet. Now it just depends, which current do you actually have on mind, when you talk  about collapsing field within coil: the original one - or this new one, induced with change of collapsing magnetic field.

At any case, once you believe, that the behavior of pancake bifilar coil doesn't actually differ from normal inductor, then the discussion of this semantic isn't interesting for me. What is interesting for me is the explanation of the role of bifilar coils in overunity circuits. And such an explanation must differ from description of normal solenoid coil, which is  behaving in classical way with respect to energy conservation law. Normal coil conserves the energy of magnetic field induced in it and it returns it back - but it never returns more than input. Once the bifilar coil returns more, it just means we missed some important piece in description of its electromagnetic field.