Anti-Mag case alternative? | Perception Neuron by Noitom

Anti-Mag case alternative?

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Strob
Anti-Mag case alternative?

Hi,
I would like to know more about the anti-mag case. What is the anti-mag material that you  are using? Is this that Mu metal?:

Your anti-mag case looks cool but I am looking for a cheaper alternative, just an ugly can big enough so I could put my suit in it and avoid removing all the sensors each time. Do you think it's possible to make my own using some cheap material?

 

Strob

I just found out that info on wikipedia: https://en.wikipedia.org/wiki/Electromagnetic_shielding
 
Magnetic shielding[edit]

Equipment sometimes requires isolation from external magnetic fields. For static or slowly varying magnetic fields (below about 100 kHz) the Faraday shielding described above is ineffective. In these cases shields made of high magnetic permeability metal alloys can be used, such as sheets of Permalloy and Mu-Metal,[5] or with nanocrystalline grain structure ferromagnetic metal coatings.[6] These materials don't block the magnetic field, as with electric shielding, but rather draw the field into themselves, providing a path for the magnetic field lines around the shielded volume. The best shape for magnetic shields is thus a closed container surrounding the shielded volume. The effectiveness of this type of shielding depends on the material's permeability, which generally drops off at both very low magnetic field strengths and at high field strengths where the material becomes saturated. So to achieve low residual fields, magnetic shields often consist of several enclosures one inside the other, each of which successively reduces the field inside it.

Because of the above limitations of passive shielding, an alternative used with static or low-frequency fields is active shielding; using a field created by electromagnets to cancel the ambient field within a volume.[7] Solenoids and Helmholtz coils are types of coils that can be used for this purpose.

Additionally, superconducting materials can expel magnetic fields via the Meissner effect.

Strob

Maybe I could buy 5 sheets of these (around 110$) but still a bit expensive:
http://www.ebay.ca/itm/Ultraperm-80-Metal-Shield-MuMetal-Mu-Metal-Alloy-...

giroudf

after looking at the permallyo sheet , i found that the price largely exceed the price of the antimag case from neuron, so i ordered the case.
After reception, i checked how it is antimag, and was a bit disappointed to find they just glue some metallic plate on each side.
The metallic plate are not fully covering  the case , so there is a big chance that the antimag effect is not perfect.
to make it better i covered one of the pocket (the wallet is made of two pockets) with the permalloy sheet.
The sheets you can buy on ebay are pretty thin and ineffective against magnets (you would need at least 6 or 7 layers), but inside the antimag case they should be ok.
It very depends from what kind of magnetic field you want to protect.
Strong magnets like loudspeakers cannot be easily stopped but weak fields like electrical wires, natural ones ar ok.
If i need to put the wallet into a plane , i will remove the neurons from the suit and put them back in the small case, and the small case into the big antimag.
 

mlawler

There's nothing you could build or make cheaper than what they offer:

https://neuronmocap.com/content/product/anti-mag-box

Strob

But if it's just some permalloy plates glued on each side, buying a 34$ cad plastic case (selling in my area: https://jpgrimard.com/fabricants/pelican/1120wf-caisse-pelican-avec-mous...) (or a 10,54" x 6,04" x 3,16" one for 50$ cad) and 2 sheets of Ultraperm on ebay would cost a lot less (and they are self adesive (8'' x 10'') 29$ cad each. I'm in Canada and 200$ USD is around 270$ cad, add custom that are so expensive (cost me 300$ in customs for the suit) so the case will end up costing me 350$ Cad. A custom solution of glued metal plates on a cheap case would cost me only around 100$ cad so 1 third the price and all I have to do is glues some pieces of metal ojn each side. It will also be smaller to carry only one suit.

Does anyone have photo on the inside of the case showing the plates glued on the sides? I would like to see their exact thickness and coverage.

Strob

And giroudf, I don't understand when you say:

"The sheets you can buy on ebay are pretty thin and ineffective against magnets (you would need at least 6 or 7 layers), but inside the antimag case they should be ok."

The little box we have to store the neurons are also very thin and those Permalloy sheets on eBay (http://www.ebay.ca/itm/Ultraperm-80-Metal-Shield-MuMetal-Mu-Metal-Alloy-...) are made of 80.3% Nickel 14.3% Iron 5.4% Molybdenum, so thats' the best alloy in the world to protect agaisnt magentic fields. On the other end, magnetic field intensity decreases as the square of the distance so they become zeroed pretty easily buy keeping a good distance. so air is also helping and is also pretty cheap ;) !

giroudf

the little boxes you receive with the neurons are pretty thick, between 1-2mm. Permalloy sheet comes in 0.1T or 0.37T that is 0.1mm or 0.35mm.
so to get the same thickness as the neuron's box you would need at least 5 layers of the 0.35T sheet.
if you calculate the price to fully cover a box like the antimag case, you would probably go to over 400$.
the plates in the antimag case are not joined because the case is round on the edge and the plate are about 1mm thick, so you got about half inch of space left around each sheet.
The plates are not permalloy, it looks like a crystalline alloy and you can probably not bend it without breaking it.
that's a pity because they could have used a layer of plastic foam to make the inside like a sharp corner box, put joined plates and add an additional layer of foam.
that is what i would have done with permalloy sheet.
it would not have added a lot of work.
but if they said the antimag case is ok, i think we can believe them. (but i added the permalloy sheet just in case)
even covering only one pocket of the wallet (half of the available space), it took me 2 sheets of 8"x11" 0.35T permalloy, about 70$

if you search "permalloy" on ebay, there are some vendor who illustrate the offer with measure of different magnetic source and the attenuation provided by different number of layers.
for a strong magnet , they totally cancel the mag field with not less than 8 layers, but the sensor of the measuring tool is very close the magnet, so i doubt you will go in that kind of proximity. check this one http://www.ebay.com/itm/Mumetal-Nikel-Permalloy-Magnetic-shielding-Sheet-Mu-metal-0-35T-30-30cm-/181425781046?hash=item2a3dd1b936:g:8rIAAOxyhS9Tid3h
you can imagine that to cover a full wallet, you would need about 3 sheets of the bigger and thickest (and most expensive) ones.
so about 120$ per layer. multiply by 5 layers and your box cost around 600$.

So again, if neuron claims their wallet is ok to store the suit equipped with neurons, for 200$ it is good business for us.
 

Strob

The little boxes I received to store my neuron are really far from 1mm, it's more like 0.1mm so exactly the same thickness as the 22$ usd 8'' x 10'' self adhesive sheets on this link: (http://www.ebay.ca/itm/Ultraperm-80-Metal-Shield-MuMetal-Mu-Metal-Alloy-...)  0.004 inches = 0.1016 mm. So I can easily make a perfect case for 100$ instead of 350$. I think the goal is to protect from accidentally going too close of a magnetic source, not to store the suit next to a strong magnet (in the test you are talking they used a neodymium magnets placed at only 5mm, which are the strongest type of permanent magnet commercially available!) My home is large and I live in the countryside so there's many large area without any mag field at all in my home. So a protection with the same thickness as the boxes Noitom provides should be more than enough. So I think I can safely save my 250 bucks.

Strob

Also did you read that info from tobiasbaumann from Noitom, meaning the neurons don't really get broken when demagnetized, you can just correct them with the software as many times as you wish.:

Our Neurons can magnetize and demagnetize an infinite amount of times without any damage to the Neurons. The demagnetization process inside NEURON DOCTOR doesn't actually demagnetization the sensor. What it does is it'll re-evaluate the magnetic environment inside the Neuron and write this environment data into the flash drive of the Neuron. The Neuron will then collect data based upon this new environment. The flash drive of our Neuron can be written 100'000+ of times under our stress tests so theres is need for worry.

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Strob

Also if you go on this link: http://www.allianceorg.com/magnetic_field_calculator.html
you can have an idea on how fast even the strongest magnet's field will go to zero when increasing the distance (so using only air as a shield by increasing air thickness).

If at 5mm you read 1200 Gauss, at 20 inches you will read 0.029. At 39.37 inches (100cm) you will read 0.004...

 

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