DIY levitation isolation device

[Andrew Pratt]

Anyone built a DIY version of one of these...how much do we need to worry about EMI with these magnets? I have an idea on how to get around the side support poles using other magnets on the front and sides to keep it floating but the number of magents would jump to 16 double what they're using (cost may be an issue too in that case)



details

[aud19]

Hey Andrew, good idea about the front/side magnets... I wonder where ya got that from :B

:roflmao: :roflmao:

Jason

[ThomasW]

Well some kind of device is needed to prevent the top from sliding. I don't think an all magnet version is a 'safe' idea.

BTW, before jumping on the bandwagon checkout the current prices for thick acrylic sheeting ......... 8O

[aud19]

Well I suppose you could make the shelves etc out of whatever material you wanted, the lighter/stronger the better obviously, but I think they use acrylic for styling/appearance more than anything else.

EDIT:I also don't see how it would be unsafe..? You would need to mount the front/side magnets on 90 degree posts that, worst case scenario the magnets fail, the posts would stop the platform from flying anywhere...

Jason

[aud19]

Did a quick render of what I'm talking about. Of course after I drew it I figured out you could likely cut the corner magnets in half by having opposing pairs on a 45 degree angle from the shelf right in the corners facing diagonally but anyways....



Jason

[Dennis H]

Cool! To keep the cost down and still have good looks, you could do it with MDF and hardwood. Build a shallow "box" with hardwood sides, MDF bottom and no top. The floating MDF top piece would sit just below the top of the hardwood sides and be hidden from normal view. The sides would keep the top from moving too far if you bumped it.

[Brandon B]

Don't think magnet cost will be much of an issue. These things cost small numbers of dollars, even in fairly big sizes (1" or so).

By the way, anyone who has some of these magnets wants to see a cool electromagnetic effect, do the following:

Find a piece of copper or aluminum tubing that is a little larger in diameter than you magnets are sized, and about 2-3' long.

Hold the tube at one end loosely between two fingers so the tube hangs down (close to) perfectly vertically.

With your other hand, drop a few of the magnets stacked together down the tube. They will semi-levitate slowly down the tube instead of falling at the normal acceleration.

Next, come back to this thread and explain why a magnet is slowed by interaction with a non-magnetic material. The techno-whizzes in the audience please refrain from responding, like to see if anyone can puzzle this one out on their own.

Fun science trick for the kids to show at school too. My friend had an old turntable that used this principle for fine speed adjustment.

BB

These

[aud19]

Cool Brandon, those are cheap! Now, who knows what to do about the EMI...?

Jason

[ThomasW]

Next, come back to this thread and explain why a magnet is slowed by interaction with a non-magnetic material. The techno-whizzes in the audience please refrain from responding, like to see if anyone can puzzle this one out on their own.

Pixie dust! ............ :T

who knows what to do about the EMI...?

MuMetal

[David Meek]

Next, come back to this thread and explain why a magnet is slowed by interaction with a non-magnetic material. The techno-whizzes in the audience please refrain from responding, like to see if anyone can puzzle this one out on their own.

Are they called "eddy currents"? Maybe? :huh:

[Brandon B]

You may pick a stuffed animal fom the top shelf.

BB

[David Meek]

I was hoping for an anatomically-correct inflata. . . oh, nevermind, gimme the purple platypus. :

Brandon, it's funny you should ask that question right now. The other evening, I was reading an interview with amp designer Dennis Morecroft of DNM in Stereophile, and he mentioned a similar experiment with a large magnet, and a tilted aluminum bar. Put the magnet on the aluminum and raise one end of the bar. The magnet will eventually slide down the bar, but at a reduced rate of speed.

FWIW, a large part of the interview focused on DNM's fanaticism on minimizing metal in amps and pre/pros due specifically to eddy currents and other EM interaction issues. Even to the point of the chassis' and cases being constructed of acrylic, and replacing metal rods in volume controls with ceramic ones. Pretty interesting stuff, IMO.

Has anyone heard any of the DNM products? Oops, O/T again. ops:

[Brandon B]

The magnet on the bar is the exact same trick. But it's much cooler to watch these little neodymium guys sort of wobble and hover their way down a tube without touching the walls. A friend took his magnets to Home Depot and was showing this to passers by with copper tube. One was so upset by it, he ran off screaming it had to be air resistance.

Back on topic, I wonder if one thing to look out for is that the space between your base and the floating shelf is not the right distance to harbor a standing wave of some frequency and acoustically couple, transmitting vibration. What's the fequency of a standing wave in a 1-2" space?

BB

[Cam McFarland]

Don't think magnet cost will be much of an issue. These things cost small numbers of dollars, even in fairly big sizes (1" or so).

Just curious, after going to this page & seeing magnet "strengths",
if one 1" magnet could handle 30#s, would the total "levitation" power
of two 1" magnets be 60#s??

[aud19]

Alright, where's the experts with some useful help Thomas? Jon? :B

Thomas, I'm afraid "Pixie Dust" does not qualify as helpul information :rofl:

Jason

[ThomasW]

Alright, where's the experts with some useful help Thomas? Jon?

Jon's either in route home or getting ready to depart from his 2 week stay in Singapore.

And my help is worth exactly what people pay for it ..... :roflmao:

Pixie dust, or was it fairy dust? Whatever the stuff was that 'Tinker-Bell' uses in Peter Pan?

Hey I saw it in the movies it must be true..... right? :T

[Brandon B]

Yes, but I haven't figured out what a magnet's "happy thought" is.

Jason, yes your lateral magnet idea would work. But you would need to load up the shelf with its final weight ahead of time to make sure the lateral magenets were lined up correctly in the vertical dimension.

As to the "levitation power", that would vary from the lifting power. The lifting power is with the magnet in contact with a metal surface, whereas this application will be acting at a distance. Probably your best bet is to buy a pair and try them to see what it is. The less distance you need between them, the greater the weight can be.

BB

[Cam McFarland]

As to the "levitation power", that would vary from the lifting power. The lifting power is with the magnet in contact with a metal surface, whereas this application will be acting at a distance. Probably your best bet is to buy a pair and try them to see what it is. The less distance you need between them, the greater the weight can be.
BB

Easier said than done, how do you keep them aligned
for the test, lol??

[aud19]

Yeah I guess the weight/height interaction could be a bit tricky... Perhaps some form of strip magnets for the corners or would those not be strong enough? They'd only be needed for directional stability and not weight so I would think they could be a fair bit weaker....?

Jason

[Andrew Pratt]

What about having a bar type magnet on each corner at a 45 degree angle so that you'd get some lift but also some directional support as well? You might need to use stronger magnets to as the lift would be reduced over the conventional horizontal arrangement but it could work I think?

[brucek]

Andrew,

I think you're going down the wrong road with those magnets.

Monks seem to have this whole levitation thing down to a science.

If this guy was into DIY HT tweaks, he'd make a fortune..... 8O

Image not available

.....brucek

[aud19]

What about having a bar type magnet on each corner at a 45 degree angle so that you'd get some lift but also some directional support as well? You might need to use stronger magnets to as the lift would be reduced over the conventional horizontal arrangement but it could work I think?

Andrew, It could even work with the "regular" round magnets in the corners at even less of an angle something like a 10-15 degree tilt on each of the corners should be enought to keep the shelf elevated while also pushing towards eachother just enough to keep it centered.... Of course you'd probably want some physical barrier "just in case"...

EDIT: The smaller angle should help minimize and height dicrepencies due to weight as well

Jason

[Hank]

Or...forget the corner magnets (they'd have to be perfectly 90 degrees and exactly the same distance from the center line of the shaft hole. Why not place a sleeve of Teflon on the four shafts that would protrude above and below the plexi (or MDF) plate a bit. Then line the four plate holes with a Teflon ring. Then, it would be Teflon against Teflon when the shafts contacted the holes. Pretty "slick" :roll: , eh?

[Dennis H]

Hank, I think the idea is to get rid of the shafts and not have any contact at all between the base and the floating platform. Horizontal vibrations would get transmitted through the shafts no matter how slick they were.

I really like the idea of 4 corner magnets tilted to keep the platform centered. Very elegant in its simplicity and very easy to build. Just make some little 15 degree hardwood wedges and glue 'em to the bottom of the magnets. If I did my sines and cosines right, at 15 degrees, the vertical force would be 97% of the magnet strength and the horizontal force would be 26%. Should be just about right.

[Brandon B]

One problem with the corner magnets is alignment. Try to push to magnets together. What happens, they slip sideways along the slightest little misalignment of force.

Now if you have this same situation at all 4 corners, and your platform is no rather perfectly balanced, one corner is going to be forced up, another down, and the whole thing is going to pitch one way or the other. Build a small scale lightweight one and try it.

BB

[Dennis H]

Brandon, although I don't have any magnets handy, my mental image (and my hazy recollection of vector physics) is somewhat different. The force increases dramatically (1/distance cubed) as you move the magnets closer together and vice versa so it will be hard for it to get very far out of level or off center. Just like a ball always rolls to the center of a bowl. If it wants to "skate," you can always tip the magnets more, i.e. make the bowl's walls steeper. I guess we'll just have to build one and see. :wink:

[Brandon B]

Ah, missed the tilted remark. I was still thinking about the earlier design with levitation magnets below, and corner magenets for centering.

I thought magnetic force wasa simple inverse square force just like gravity, EM and everything else. 1/distance cubed?

BB

[aud19]

Brandon, although I don't have any magnets handy, my mental image (and my hazy recollection of vector physics) is somewhat different. The force increases dramatically (1/distance cubed) as you move the magnets closer together and vice versa so it will be hard for it to get very far out of level or off center. Just like a ball always rolls to the center of a bowl. If it wants to "skate," you can always tip the magnets more, i.e. make the bowl's walls steeper. I guess we'll just have to build one and see. :wink:

So Dennis, are you volunteering?! :P

Jason

[Dennis H]

Brandon, I was wrong about the force between two disk magnets. It's actually 1/D^4 at large distances but doesn't change as fast at small distances relative to the magnet diameter. It's because of the dipole nature of the magnet.

http://www.exo.net/~pauld/activities/magnetism/forcebetweenmagnets.html

Jason, yeah I'll put that on my to do list (I'm only a couple of years behind on it ). Actually, if I still had a turntable, I'd go for it in a second. Looks like a great way to keep the stylus from bouncing. I'm not sure it's real high on my list with digital sources and solid state components although some claim it helps even then.

[Andrew Pratt]

I won't be building one for awhile now having just sold my DVD player for a monster DVD jukebox...I'd like to try it later on though for what ever transport I end up buying for CD's...in the mean time guys work out the bugs for me would ya Actually I might build one for fun as I've got a few idea's I'd like to try

[aud19]

Ok so I woke up this morning and had this in my head so I decided to quickly render it this afternoon :B

We had decided that if you had both magnets underneath and on a 45 degree angle both in the XY plane and Z plane that it would both levitate and have directional stability. However it wasn't adjustable! :B

This "arm" would work similar to the adjustable tracks I'm sure most of you have seen many times before. Anyhoo, here's pics :B

[cjd]

Getting it so all forces are entirely perfectly in balance goes to heck as soon as you put anything on it that might interact even slightly with the magnetic forces. IF it's entirely floating.

That's if I remember the experiments I did in my youth with similar things.

Nothin to stop y'all from having fun experimenting. :T

C

[downhill]

I love this type of stuff....

I've been playing with this same idea for a couple of years when I have time.

First...from what I read, there isn't a way to truly decouple the two platforms without using some kind of computerized setup and running electromagnets...

Don't care what physics sez....I've just had to try. After all, MDF is cheap as are them magnets....

The only thing I've come close to get to working is using repelling forces on the platforms facing each other...and made so the top or the bottom "slides" over the other with side pieces...with an air gap and repelling forces on the side pieces....only use a smaller magnet as your only keeping the sides from touching the other platform and not trying to levitate with them. The platform will still twist somewhat.

Also...you really need to plan what magnets to use. You want the platforms to have a small air gap. Why? That helps keep it level. If the magnets are too strong..the heavier side will sink lower.



The idea posted in the above picture is really about the only way you can get it to work without a lot of hassle. The only thing is.....it's still coupled..Probably not like sitting on a shelf though and from my own experiences......it works ok..

The magnets are cheap enough though...you can find them in bulk on ebay or here...

http://www.gaussboys.com/default.php

There is a lot of discussion on this idea on the web. Try a google search..