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rotor magnets

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Fri Jul 18, 2008 10:25 pm PostPost subject: rotor magnets
lostcauses
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A post to were I can follow this stuff on them.

Al
"but my rotor magnets came from Active Surplus in Toronto"

""I have done some rough strength measurements on the rotor magnets (I got them from a surplus store in downtown TO, and I think I got the last 20 they had). They are nickel-plated NdFeB's with estimated energy product 35-40 MGO. The field viewing film doesn't reveal anything obvious."

"
alsetalokin wrote:
OK, like I said I don't have very good measuring tools at the cavern, and I don't like using my good micrometers on magnets anyway, so I generally use a plastic dial indicator caliper made by General. I just checked again using this caliper. The rotor magnets all measure between 0.53 and 0.54, or very close to 14 mm, using this caliper.
This is "nominally" 1/2 inch.


Gauss readings

alsetalokin wrote:
Toroidal coil==even weirder. Shouldn't be much flux leakage from the toroidal coil.

Anyway, I did some measurements with the Allegro Microsystems 3515 ratiometric HE sensor, 5.0 mV/Gauss.
Power supply = HP regulated benchtop supply @5.00 VDC
Sensor monitored on oscilloscope (calibrated voltage)
Measured the magnet marked "5" in the HS vids
Measured magnet in place in rotor (all magnets in place)
Technique: HE sensor mounted on skinny popsicle stick, inserted in slot in rotor and moved toward magnet until sensor saturated (output at rail); distance from chip surface to magnet measured at that point
Results:
"Black" end of magnet--approached with label side of chip, saturation at 6.5 mm, 0.00 volts
"Black" end of magnet--approached with back side of chip, saturation at 6.5 mm, 5.00 volts
"White" end of magnet--approached with label side of chip, saturation at 6.0 mm, 5.00 volts
"White" end of magnet--approached with back side of chip, saturation at 5.0 mm, 0.00 volts

(sensor reads 2.50 volts when distant from any magnets)
(distances accurate only to 0.5 mm)

Vidio
http://yirkha.fud.cz/whipmag/HallEffect1.avi


Other on readings:
Fri Jun 06, 2008 3:12 am
alsetalokin wrote:
Ahh, I wondered why it was L instead of Z. Impedance matching, in the mechanical sense, has to do with momentum transfer between collliding, or mysteriously at-a-distance-interacting, objects that may be of wildly disparate masses and/or velocities. If your billiard balls are all the same mass, they bounce differently off one another than, say, a mixed assortment of bowling and basket balls. When Harvey drags a finger on a stator in order to allow the rotor to synch and be driven, he is essentially altering the mechanical impedance of the stator to more closely match the rotor.

I don't recall saying that I had actual gaussmeter readings at the surface of the magnets. K&J publishes this info for their magnets, IIRC (the stator magnets). Is it really important to know the value for the mysterious generic rotor magnets? If so, it will have to wait for a while, as I can't spare the lab time right now, things are quite hectic. Sorry.
(It just occurred to me, though, that since the field strength of the stator magnets can be looked up at K&J, an oscilloscope and sense coil could be used to make a rough comparison and an educated guess at the rotor magnet field strength. Maybe I could do this at home over the weekend. But I can't use any of the actual Gaussmeters at the lab until this current cycle of madness, er, discovery has run its course.)



Al Sat May 03, 2008 12:36 am
"Sometimes it's just easier to build what I need, so I did some magnetometry using a couple of Allegro Microsystems ratiometric Hall effect sensors; they produced nice Lissajou figures on the old Philips scope that showed a bit of asymmetry in the rotor fields. Was it fun, and did I learn a lot from it? Yes, absolutely. Do I think it revealed anything about the behavior of interest? No, it did not. I don't believe my sensors were picking up the true driving fields (if such exist.) Actually, that was, in my mind, the main result of my experimentation with the gaussimetry. "



other info



Due to this by Oc it shows his stator will float,

http://s285.photobucket.com/albums/ll48/overconfident/wacko/?action=view&current=017.jpg

Als response to this
"Second, I tried the OC levitating stator, and I can report that to all appearances, my magnets act just the same as his do in his video. It's pretty weird to see that stator jumping up and down as the rotor slows. When the rotor is spinning fast, the stator floats at just about the same height wrt the rotor as the mounted stators. But when the rotor slows sufficiently enough, the floating stator starts bouncing up a little and mostly down from that position, and usually mostly comes to rest in the floating position.

I also tried (wait, is this a third thing?) a couple ring magnets, one a ceramic and one a strong NdBFe. They too levitate quite nicely and squirm around their central pole in a sensual manner somewhat reminiscent of...Ahem. Yes."
Also a note from on this
"Harvey, Tue May 20, 2008 9:49pm
Also, thanx for doing the suspended stator test. I think this is important as I am able to obtain AGW with my weak rotor magnets but am not able to suspend the stator. So I am concluding here that my magnets are too weak and I will increase the size a bit to just where they will suspend the stator and see what happens. "


So more as I find it of this thread gets added at..
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Wed Jul 23, 2008 12:34 am PostPost subject:
lostcauses
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"Al- Dec 27th 2007
Well, I think it's jumping the gun a bit, but here are some specs on the 13x8 test jig, so
that Debaser can play around. Bearing in mind that there will be additions to the design
as OC has pointed out.
Magnets:
Stator Magnets: 13 ea. K&J p/n 834DIA N42 grade, ring, 0.5 in dia, 0.25 in thick, ~3/16
central hole, diametrically polarized.
# Surface Field: 5340 Gauss
# Brmax: 13,200 Gauss
# BHmax: 42 MGOe
Rotor magnets: 8 ea. generic N35 grade, bar, 0.25 in dia, 0.5 in length, axially polarized.
#BHmax: ~35 MGOe
Stator magnet spacing: on a circle, radius 3.375 in, spaced 1.6 in apart around the circle
(or every 27.7 degrees)
Stator magnets each mounted on (above) single ball bearing, 1/2 x 3/16 x 1/8"
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Wed Jul 23, 2008 12:44 am PostPost subject:
lostcauses
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Al- Jan 3th 2007


They are generic N35 grade NdBFe, so BH product is approx. 35 mega-Gauss-Oersteds. I
don't know what the surface field strength is.
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Thu Mar 12, 2009 5:15 pm PostPost subject:
lostcauses
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"OK, so I haven't replicated Axle's system exactly, but here's what I did:
I used a Minute Maid orange juice bottle, 450 ml (didn't these used to be 500 ml?)
and I used a Canadian dime, 1980 (99.9 percent nickle, so worth about 2 cents on the spot market) and I taped this dime to the inside (underside) of the plastic top to the bottle, which material is black plastic 0.06 inch thick. I ballasted the bottle with water, and I put the bottle on the digital kitchen scale, 1 gram resolution. I adjusted the weight of the bottle until I bracketed the magnet's "pickup" strength. The spare rotor magnet was able to pick up 173 grams, and was not able to pick up 174 grams. Interestingly, with this magnet, I felt that one pole seemed stronger than the other, although this difference was below the resolution of my scale. The stronger pole was the one that attracts the South-pointing compass needle."

http://www.steorn.com/forum/comments.php?DiscussionID=61567&page=10#Item_27

http://retroroast.net/store/OrangeJuice.jpg

"Yep, my bottle looks the same but the label is different. Mine says "Jus D'Orange, Fait de concentre, 100% JUS, Excellente Source de Vitamine C" and of course, that 450 ml.

(The first one, not the second.) "
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Fri Mar 13, 2009 6:22 pm PostPost subject:
lostcauses
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EDIT to add: It's always something. I can't find my early Canadian dimes, for some reason. But I did find a 1960 Canadian Nickel, which is also supposed to be 99.9 percent nickle. I'm gluing it to the top of a 450 ml minutemaid OJ bottle, which I will ballast with lead and water, as before. Results soon

I can pick up 771.43 grams
I cannot pick up 772.11 grams
(I can't decant the water more accurately without a better setup)
This is with the date side (the buffalo) up.
Once again, one pole seems slightly stronger, but still within the bracket range above.
From steorn thread posted above.
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