Please provide the links for the gunderson patent. Look at Don Smith pdf for his circuits on his rod generators and Terfenol-D insights as an option.

This is all conjecture on my part, I don't know

If you vibrate a metal, like striking a gong, you can measure a magnetic output. If you have magnetic flux that you can turn on and off you can generate current. If you had harvesting coils around fixed magnetic fields from permanent magnets, and had some element(magnetostrictive) that you could excite to bend or disrupt the flux, you might be able to augment the effect. Of course you need to optimize the relationship with the natural resonance of the rod, the exciter coil resonance and the harvesting coil(s) resonance. It should all sing together in harmony.

There maybe a song that interacts with the Earth magnetic fields, because magnetism might be a reflection or tuned relationship from the Earth's Geo structure.

I would place a harvesting coil with a scope attached, and sweep the frequencies until I found a sweet spot. If it is a rod shape you can strike it like a tuning fork, and use a spectrum analyzer or phone app, to determine the ring frequency, that should be the natural resonance frequency. So you know what frequency to create a standing wave.

Terfenol-D is like magic, because it is not just magnetic aggregator like a ferrite rod, nor a coil that creates magnetism through current flow. I think it creates magnetism just by vibration, and I assume lots of it. They are used on sonar for subs.

Terfenol-D is a material which, when magnetised, increase in length. For this reason, it is used in some loudspeakers and, as you say, in sonar. It is very expensive and I cannot see any point in spending unless you want to use this property of it.

https://en.wikipedia.org/wiki/Terfenol-D

I don't follow its purpose in the D Smith invention with the rotating interrupting disc.

What might be interesting might be to see how much power it takes to energise and get an expansion in length and then see what sort of power might be generated by having that change in length move a coil in a magnetic field.

The stuff can be found on Alibaba and there is a firm in the States selling it. I reckon £500 - £700 would be what it might cost to get a rod the size of a pencil.

Here is an a Don Quote from hereI think the point is varying the magnetic flux which can be harvested for power generation. Same as the rod designs.

patent

https://patents.google.com/patent/US8093869B1/en

This is the patent. In it the magnetostrictive response, the change in permeability when compressed, of the material is utilized to generate an output current. And the placement of the output coil serves to create a magnetic field which acts as positive feedback on the compression of the material.

It seems to me that using a laminated Galfenol or Terfenol-D rod would be ideal. The laminate would reduce eddy currents at ultrasonic frequencies.

I was curious if anyone had tried this. Several years ago I contacted Etrema regarding getting a laminated Terfenol or Galfenol rod made and they said it would be hundreds of dollars so I stuck with experimenting with ferrite rods but the current output was very low and I couldn't observe the effect described in the patent regarding lower input current or self reinforcing oscillations within the rod, but I might have been missing something.

I tried different types of ferrite. Unfortunately, I broke my most responsive ferrite and couldn't find one as good though I tried many different types primarily ordered through ebay from the Ukraine.

So you are trying to squeeze this thing to give current?

Patent

It's an interesting concept to me. Do you not agree?

Well, not necessarily disagree. But I look at the magnitude potential. I piezo element does somewhat the same thing, we all should be familiar with a gas igniter that produces enough current to create spark, so we know the effect is achievable. The question how big of an energy pulse do you need to place to get a sustained energy output, and is there gain from the process to be viable as an energy source.

I assume that's what you are trying to achieve.

patent

The way I have interpreted the patent is you drive the end of a rod with a piezo to setup a standing longitudinal wave. At the third harmonic two nodes are setup and at each node there is the greatest swing in expansion and compression.

Loaded output coils are placed at the nodes thus generating current in the coils. The generated current has a second order effect, which is where the overunity is: the current through the coils generates a magnetic field which acts on the rod to actually add to the compression/expansion of the rod at the nodes.

The output is proportional to the magnetostriction response of the rod as well as other factors like properly placed secure mounting.

In a bigger sense, and this is just my opinion, instead of trying to make a device that is only manipulating magnetic or electrical fields, it mixes physical and magnetic action to bypass the classical limitations of E/M fields which are a zero sum game with no path to overunity (I know that's debatable). The physical action indirectly induces a change in the magnetic permeability of the rod which is what ultimately allows this thing to produce output in excess of the input.

The subject matter is exciting, no doubt.

I like the idea of feedback, that really has to be one of the mechanisms of over unity. If you have the Terfenol-D rod, then you have a commitment I couldn't make. I would be interested in the response once you placing a resonant vibration through it. I must point out that in Don Smith's Rod generators, he said that a viable substitute was thin walled stainless steel, that had remarkable results, and Terfenol-D was overkill.

Find Text "stainless steel tube"

In thinking about a vibration device, here are some of my thoughts:

The patent description you lay out is interesting because, In Don Smith's rod device, the placement of the exciter coil is not on the end, but I assume would be where the node is on a vibrating rod length with a standing wave exists from resonating. In fact it is known to be at .224 of the length of the bar.

https://youtu.be/_aPl4Taroow?t=481

https://youtu.be/sIw0Fh-fXIM?t=45

This allows free oscillation of the bar, as long as the bar is supported at the node, and possibility of the center of the exciting coil?

The pickup coil may need to be at the end of the bar, as that is where sound emanates, so it seems the maximum of the wave energy.

https://youtu.be/sIw0Fh-fXIM?t=112