Welcome
Username:

Password:


Remember me

[ ]
[ ]
Online
Guests: 30, Members: 1 ...
Cristian viewing forum.php

most ever online: 333
(Members: 3, Guests: 330) on 06 Jun : 15:15

Members: 3376
Newest member: mike_van_eman
Members Birthdays:
All today's birthdays', congrats!
Andrea87 (30)
WertWiktor (23)
Bill k (48)


Next birthdays
06/23 Bill Fain (63)
06/24 SpyrosF (59)
06/24 Berni (26)
Contact
If you need assistance, please send an email to forum at 4hv dot org. To ensure your email is not marked as spam, please include the phrase "4hv help" in the subject line. You can also find assistance via IRC, at irc.shadowworld.net, room #hvcomm.
Support 4hv.org!
Donate:
4hv.org is hosted on a dedicated server. Unfortunately, this server costs and we rely on the help of site members to keep 4hv.org running. Please consider donating. We will place your name on the thanks list and you'll be helping to keep 4hv.org alive and free for everyone. Members whose names appear in red bold have donated recently. Green bold denotes those who have recently donated to keep the server carbon neutral.


Special Thanks To:
  • Aaron Holmes
  • Aaron Wheeler
  • Adam Horden
  • Alan Scrimgeour
  • Andre
  • Andrew Haynes
  • Anonymous000
  • asabase
  • Austin Weil
  • barney
  • Barry
  • Bert Hickman
  • Bill Kukowski
  • Blitzorn
  • Brandon Paradelas
  • Bruce Bowling
  • BubeeMike
  • Byong Park
  • Cesiumsponge
  • Chris F.
  • Chris Hooper
  • Corey Worthington
  • Derek Woodroffe
  • Dalus
  • Dan Strother
  • Daniel Davis
  • Daniel Uhrenholt
  • datasheetarchive
  • Dave Billington
  • Dave Marshall
  • David F.
  • Dennis Rogers
  • drelectrix
  • Dr. John Gudenas
  • Dr. Spark
  • E.TexasTesla
  • eastvoltresearch
  • Eirik Taylor
  • Erik Dyakov
  • Erlend^SE
  • Finn Hammer
  • Firebug24k
  • GalliumMan
  • Gary Peterson
  • George Slade
  • GhostNull
  • Gordon Mcknight
  • Graham Armitage
  • Grant
  • GreySoul
  • Henry H
  • IamSmooth
  • In memory of Leo Powning
  • Jacob Cash
  • James Howells
  • James Pawson
  • Jeff Greenfield
  • Jeff Thomas
  • Jesse Frost
  • Jim Mitchell
  • jlr134
  • Joe Mastroianni
  • John Forcina
  • John Oberg
  • John Willcutt
  • Jon Newcomb
  • klugesmith
  • Leslie Wright
  • Lutz Hoffman
  • Mads Barnkob
  • Martin King
  • Mats Karlsson
  • Matt Gibson
  • Matthew Guidry
  • mbd
  • Michael D'Angelo
  • Mikkel
  • mileswaldron
  • mister_rf
  • Neil Foster
  • Nick de Smith
  • Nick Soroka
  • nicklenorp
  • Nik
  • Norman Stanley
  • Patrick Coleman
  • Paul Brodie
  • Paul Jordan
  • Paul Montgomery
  • Ped
  • Peter Krogen
  • Peter Terren
  • PhilGood
  • Richard Feldman
  • Robert Bush
  • Royce Bailey
  • Scott Fusare
  • Scott Newman
  • smiffy
  • Stella
  • Steven Busic
  • Steve Conner
  • Steve Jones
  • Steve Ward
  • Sulaiman
  • Thomas Coyle
  • Thomas A. Wallace
  • Thomas W
  • Timo
  • Torch
  • Ulf Jonsson
  • vasil
  • Vaxian
  • vladi mazzilli
  • wastehl
  • Weston
  • William Kim
  • William N.
  • William Stehl
  • Wesley Venis
The aforementioned have contributed financially to the continuing triumph of 4hv.org. They are deserving of my most heartfelt thanks.
Forums
4hv.org :: Forums :: General Science and Electronics
<< Previous thread | Next thread >>   

Magnetic levitation

Go to page  1 2 [3]
Author Post
flannelhead
Sun Jul 06 2008, 03:14PM
Registered Member #952
Joined: Mon Aug 13 2007, 11:07AM
Location: Finland
Posts: 388
Bringing the old but interesting topic up. I have a question: could hall switches (nonlinear; just on and off) used instead of linear hall effect sensors? Or do the sensors absolutely have to be linear?
Back to top
cjk2
Sun Jul 06 2008, 04:53PM
Registered Member #51
Joined: Thu Feb 09 2006, 04:17AM
Location: Tennessee Tech University, Cookeville, TN, USA
Posts: 263
Using switches rather than sensors would probably lead to the object vibrating. Linear feedback is really needed for stable levitation.
Back to top
flannelhead
Mon Jul 07 2008, 08:17AM
Registered Member #952
Joined: Mon Aug 13 2007, 11:07AM
Location: Finland
Posts: 388
Okay then. I'll just have to use infrared phototransistors. Hall sensors would've been so cool.
I'd want to get rid of the need for a dual power supply for the op-amps. Maybe a noobish question, but how could this be done?
Back to top
Conundrum
Tue Jul 08 2008, 06:17PM
Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: Republic of Guernsey
Posts: 3774
You can get linear sensors from old broken 5 1/4" floppy drives. Other sources include old style Panasonic VCRs (three are used in the capstan motor) as well as some hard drives.
There is a modern equivalent which is SMD, however its inferior in sensitivity and directionality to the 4 pin SIL equivalent.

It may also be possible to modify the read head on a hard drive (this consists of a very small nanowire) with a constant current as a magnetic sensor, though this is very finicky and hard to do.

Regards, -A
Back to top
Website
MagLev
Wed Oct 29 2008, 03:05PM
Registered Member #1512
Joined: Fri May 30 2008, 01:16AM
Location:
Posts: 4
Tesladownunder wrote ...

Reaching wrote ...

.. does anyone know if its possible to levitate a copper or aluminium disc stable via eddy currents(induction)?

It is possible to levitate a dish shaped copper or Al disc vertically but the power is large and the dish may be close to melting. I've not been able to manage it but 50Hz is rather low to work well.

You can in fact pick up non-magnetic washers with an AC electromagnet with an additional copper washer added to the core. Now a levitator for aluminium objects would be really cool

Peter


Actually, there are several types of levitators for aluminum (and, presumably, copper) objects. The book Propulsion Without Wheels by E.R. Laithwaite is an excellent source for these levitators. Unfortunately, the book is rare, expensive, and out-of-print. I had to get it through inter-library loan. The book is mainly about induction motors, but has a whole chapter just on magnetic levitation, with plenty of how-to diagrams and theory. It's a great resource.

Keep in mind, though, that any sort of induction levitator for copper, aluminum, or other diamagnetic materials will cause the materials to become hot if they are pushed deeper into the magnetic field than is necessary for them to levitate (i.e. an aluminum bowl which floats at 12 inches and stays cool will become very hot if pushed 6 inches into the magnetic field with a nonconducting object such as a wooden rod).

Here's a link to another aluminum levitator that works on the same principle. http://aether.lbl.gov/www/classes/p10/levitator.gif
Back to top
cjk2
Wed Oct 29 2008, 08:44PM
Registered Member #51
Joined: Thu Feb 09 2006, 04:17AM
Location: Tennessee Tech University, Cookeville, TN, USA
Posts: 263
"Maglev", your link is broken. Now that this topic is active again, ill go ahead and post my most recent work. This is repulsive levitation.

Back to top
101111
Wed Oct 29 2008, 09:41PM
Registered Member #575
Joined: Sun Mar 11 2007, 04:00AM
Location: Norway
Posts: 263
cjk2 wrote ...

"Maglev", your link is broken. Now that this topic is active again, ill go ahead and post my most recent work. This is repulsive levitation.





Wow, That is impressive! Please, make a project thread out of it so we can see more ;)
Back to top
cjk2
Thu Oct 30 2008, 03:11AM
Registered Member #51
Joined: Thu Feb 09 2006, 04:17AM
Location: Tennessee Tech University, Cookeville, TN, USA
Posts: 263
I will actually be updating rfhv.com soon to reflect my 5th version design. In the mean time, enjoy a picture of my controller board.

Back to top
MagLev
Mon Jan 12 2009, 01:10AM
Registered Member #1512
Joined: Fri May 30 2008, 01:16AM
Location:
Posts: 4
All righty, let's try to fix that link...

http://aether.lbl.gov/www/classes/p10/levitator.gif

Hopefully that'll do it. The device pictured here is very similar to a description of a levitator found in Harry F. Meiners' Physics Demonstration Experiments (more info can be found at Rick Hoadley's excellent magnet site- see link below.

http://www.coolmagnetman.com/magpie.htm

As he notes, a levitator like this is quite expensive and labor-intensive. However, they are quite fascinating to see in action. Here's a picture of one (with a funny comment about cooking pancakes).

http://blog.modernmechanix.com/mags/qf/c/PopularScience/11-1939/med_floating_bowl.jpg

Now to build/fix my own levitators when the parts arrive in a few days...

EDIT: Links still aren't working. Just copy and paste into your browser.
Back to top
aonomus
Mon Jan 12 2009, 02:04PM
Registered Member #1497
Joined: Thu May 22 2008, 05:24AM
Location: Toronto, Ontario, Canada
Posts: 799
@ MagLev: Your links are incorrectly formatted (valid url, but you borked the bbcode)

As for the levitators, could a 'quick, dirty and cheap' version be made using MOT's perhaps with the top "I" sections ground off exposing the E section?
Back to top
MagLev
Tue Jan 13 2009, 12:22AM
Registered Member #1512
Joined: Fri May 30 2008, 01:16AM
Location:
Posts: 4
I've never seen a microwave oven transformer, so I am uncertain. However, I do know one thing: an essential component of eddy current levitators (which is what an aluminum or copper levitator is) is the requirement that there be (at least) two currents, and that the two currents be out of phase with each other. For instance, one type of levitator described in Propulsion Without Wheels involves levitating an aluminum sphere. To achieve this, the author recommends two methods. In the first, one coil is placed inside another, and the two are separated by some sort of iron ring or pipe (to concentrate the field). These two coils are then powered by different legs of a 3-phase supply, giving you two coils that are 120 degrees out of phase.

A variation on this (also described in the book) is where you have the same setup, with the difference being that the inner coil is replaced with a piece of very thick, solid (i.e. not split) copper pipe. In this case, current is induced in the copper pipe by virtue of the magnetic field generated by the first coil. So you still have some sort of phase difference between the outer coil (powered by AC) and the inner "coi", a.k.a. the pipe, which is "powered" by eddy currents.

Either one of these setups is used to levitate a small aluminum sphere.

A variation on this involves levitating a piece of aluminum shaped something like a dish or pie pan. This is described in Meiners' Physics Demonstration Experiments book. However, this one requires 3-phase power.

So I don't know about the MOTs- all I know is that there would need to be some sort of phase difference between different windings. Also, from my research, the shape and size of the object to be levitated is fairly critical, depending on your setup. That is, the sphere levitator described above will only levitate spheres of a specific size- it will not levitate discs, sheets, toroids, or whatever else. So I don't know what shape an "MOT levitator" would be best suited for, either.
Back to top
BigBad
Sat Nov 27 2010, 07:53AM
Registered Member #2529
Joined: Thu Dec 10 2009, 02:43AM
Location:
Posts: 599
Classic Laithwaite maglev video of his 'magnetic river'. Rather cool!



There's also a paper here:



that talks about Laithwaites lev stuff quite a bit.
Back to top
BigBad
Fri Mar 16 2012, 05:45PM
Registered Member #2529
Joined: Thu Dec 10 2009, 02:43AM
Location:
Posts: 599
FWIW a few months back I built a maglev set up using a combination of permanent magnets for the lift and a spinning aluminium disk giving the electrodynamic levitation for the stability. Air gap was about a centimeter.

I did some measurements of the drag on the aluminium from the magnets and it was only about 50-100 mN, so the overall lift power seems to be about a watt per kilogram, or so, and I could probably get it a lot lower.

Technically it was only pseudo levitation in the actual demo version, because I had to tether it laterally against the electrodynamic drag- my final version works like a train, so it will be pulled along by a propulsion system (probably a linear motor) rather than the tether.
Back to top
BigBad
Sun Jul 22 2012, 09:44PM
Registered Member #2529
Joined: Thu Dec 10 2009, 02:43AM
Location:
Posts: 599
This is pretty cute, albeit a bit wobbly looking because of the lumpy fields they're generating:

Back to top
invintive
Wed Oct 09 2013, 02:05AM
Registered Member #26228
Joined: Tue Jun 25 2013, 12:22PM
Location:
Posts: 1
I know this is an old thread, but I am trying to build a magnetic levitator and I am a self taught electronics hobbyist (noob). Currently I have a working levitator, but it becomes quite unstable if it is disturbed at all. I am hoping to implement the feed forward circuit in the first post, but I am unfamiliar with OPAMPs. How am I supposed to power it? does it require a negative voltage?

Any comments, suggestions, or ideas would be greatly appreciated!
Back to top
BigBad
Sun Oct 20 2013, 07:42PM
Registered Member #2529
Joined: Thu Dec 10 2009, 02:43AM
Location:
Posts: 599
There's plenty of circuits around to do that.

I haven't tried it:


Back to top
Go to page  1 2 [3]

Moderators: Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Bjørn, Dave Billington, Steve Conner, Wolfram, Kizmo, Mads Barnkob

Jump:     Back to top

Powered by e107 Forum System
 
Legal Information
This site is powered by e107, which is released under the GNU GPL License. All work on this site, except where otherwise noted, is licensed under a Creative Commons Attribution-ShareAlike 2.5 License. By submitting any information to this site, you agree that anything submitted will be so licensed. Please read our Disclaimer and Policies page for information on your rights and responsibilities regarding this site.