Maglev trains

[shadow67]

ye thanks

[CraigD]

can somebody tell me how do i tell which side of the electromagnet is north and which side is south?

Grab another magnet that's marked. Hold the North end upward, and put the other magnet near the north end. If it attracts, then the end of the "other" magnet is south. If it repels, then it's north.

 

You can also get a compass…

And, of course, if you want to change an electromagnet’s polarity (swap its N and S poles), just reverse its current (swap the battery terminals the wires are connected to).

 

If you want to calculate the electromagnet’s polarity using theory, use the “right hand rule”: if you have wrapped wire around a nail in a counter-clockwise direction (looking downward) from top to bottom, and you attach the top wire to the negative terminal of the battery, the bottom to the positive (electric current flows from negative to the positive), wrap the fingers of your right hand in the direction of the current flow, and note the direction your thumb is pointing – up. The N pole of the electromagnet is its top, pointing up.

[shadow67]

i just wanted to know in a little detail if someone can explain me how to position those electromagnets along the track with its wires. and how many switches will be required for turning on and off the magnetic field? my track is 20" in width and 40" in length.:eek_big:

[CraigD]

i just wanted to know in a little detail if someone can explain me how to position those electromagnets along the track with its wires. and how many switches will be required for turning on and off the magnetic field?

Something like the attached thumbnail, I would think, where each of the clusters of 6 dots is a double pole/double throw switch. (note that the nails should have many more wraps than the sketch shows. You can buy slide or toggle DPDT switches at stores like (a decent) Radio Shack, or coble workable versions out of wire, foamboard, and bits of metal.

 

You’ll likely want to try different distances between electromagnets to see what works best. Such tinkering is where all the fun is.

[shadow67]

Something like the attached thumbnail, I would think, where each of the clusters of 6 dots is a double pole/double throw switch. (note that the nails should have many more wraps than the sketch shows. You can buy slide or toggle DPDT switches at stores like (a decent) Radio Shack, or coble workable versions out of wire, foamboard, and bits of metal.

 

You’ll likely want to try different distances between electromagnets to see what works best. Such tinkering is where all the fun is.

so does it mean that if you turn the electromagnet on it will attract the train and if you turn it off it will repel the train?

and can you please tell me a little simple terms because i am still in high school LOL.

[CraigD]

hey craig another question where exactly have you placed those nails? have you placed it on the track between the two magnet strips or where. and is the heads of those nails that is gonna be attracting and repelling the train?

Yes and yes

and can you tell me tht to move the train for do i have to keep turning on and off all the switches quickly in order for the train to move forward or what? please expalin in a little detail

Just switching all the electromagnets to “attract”, then switching each one off as the train passes it, should be adequate. (Which, incidently, would require only SPST switches) Switching them to “repel” as the train passes should make the train go faster, but may not be necessary

.here is a site of a radio shack staion : RadioShack.com - Cables, Parts & Connectors: Component parts: Switches: DPDT Heavy-Duty Slide Switch please check and tell me if it is okay and how many of them to buy?:eek_big:

These would work, though they’ve much more current capacity than needed. Ones with a center off position would be better, and give you more flexibility in experimenting with controlling the train’s motion, but look to be much pricier ($3.49 vs. $1.40 each).

 

Don’t be tempted to try using 120V, even though the switches can handle them. For safety reasons, it’s best to use batteries whenever possible, since they can give you a lethal shock.

 

My thought was to space the electromagnets about as far apart as the length of the car train, so I’d calculate the number of switches you need based on that. Keep in mind that you can keep the switches for later projects, and much of the value in this kind of project comes from trying different arrangements, so, budget permitting, more is better.

[CraigD]

do i have to connect a 9 volt battery to each iron nail?

Not necessarily. I’d try connecting them all (in parallel, as my little sketch shows) to one battery, then, if they prove too weak, rewire to reduce the number of electromagnets connected to each battery. You could safely put 2 9V batteries in series to make an 18V battery, but I’d stop at 2, as that’s beginning to get into “ouch” territory for electrical shock or hot batteries.

what length and thickness should the iron nail be?

The bigger the better, I think. The bigger the nail, the more windings it can easily hold, and the greater its magnetic field strength for a given electric current. Not too big, or the wrapped nail may tear up the foamboard too much, and be hard to manage underneath. You’re going to have to build something to support the track off of the table surface to provide room underneath it for the nails and wires, which will impose some practical limits on how long the nails can be – 4 inches or so, would be my guess.

can you tell me what type of switches do you mean?

Nearly any kind will work. Use you imagination, and experiment. Find what works best.

and finally do i have to place another strip of magnet between the two strips under the train so that it is right above the iron nail heads?

That sounds like a good idea. Other stuff could work, too, like a steel washer, a strip of steel staples – pretty much anything that’s attracted by a magnet.

does the iron nail head have enough power to attract the train?

That’s the big question, isn’t it? I suspect it will, because the train has so little rolling – err, floating friction, but you wont really know until you’ve tried. If it doesn’t, you have a lot of flexibility to reposition magnets, rewire them, etc.

 

Projects like this wouldn’t be much fun if you were absolutely certain the first, guessed-at design, would work. Plan to allow time after your initial build to try new things, even if it does work on the first try.

 

PS: You’ve been using PMs a lot for what would have been good posts in the threads. It’s best to keep all the discussion in the thread, where all can read and comment on, and use PMs only for communication of a personal nature that you don’t want the whole world to see.

[shadow67]

does anybody know a specific type of magnet that would create a good repulsion for a model maglev train. would a screw replacing a nail work better? PS. i have a plywood base so it is pretty sturdy and good looking.:shrug:

[Jay-qu]

Do you need some permanent magnets aswell? The ones you can get out of a computers hard drive are normally very strong. If your making an electromagnet a nail is recomended as its probably made from iron, so it will have a good field induced within it - note that there may be better materials for induction, but im not sure what property makes them better suited and where to find it.

[shadow67]

i am talking about permanent magnets as they will be the ones levitating the train.

[shadow67]

The bigger the better, I think. The bigger the nail, the more windings it can easily hold, and the greater its magnetic field strength for a given electric current. Not too big, or the wrapped nail may tear up the foamboard too much, and be hard to manage underneath. You’re going to have to build something to support the track off of the table surface to provide room underneath it for the nails and wires, which will impose some practical limits

on how long the nails can be – 4 inches or so, would be my guess

 

do the nail heads have to be flush with the bottom ply or placed a little bit up towards the magnet or piece of metal so that it can attract and repel much better?and when using a switch for toggling attraction and repelling modes for an electromagnet does it mean that when you switch it on the electromagnet will attract and when you switch it off the electromagnet willl repel? PS. how does turning off the electromagnet repel the magnet? or is it the positive or negative current that does that? can somebody please go to RadioShack- Audio/Video Electronics, MP3, LCD TVs, GPS, Digital Cameras, DVD Players, Accessories and send me a thumbnail of the picture of a a suitable SPST switch that can repel and attract the magnet or piece of metal?:confused: :lightning :D with a centre off position? i tried but couldnt find it. if the nail heads are not strong enough what about placing a small bar of iron wrapped with copper so it has more surface area . will it have much more effect?

[Jay-qu]

The changing of positive current to neg will flip the poles of the magnet.

[shadow67]

hey thanks jay-qu but i just wanted to know that if the iron nail head is not strong enough for attracting the train what about keeping a 2" by 1" iron bar wrapped with thin insulated copper wire? for more surface and more attraction? or will this setup pull the train down?:doh:

PS. i am planning to attach a 9 volt battery to each peice of iron ( bar or nail).so please help in making a decision:D. I have also gone to this site Tubular Electromagnet     E-66-38     Magnetic Sensor Systems

can somebody please go to this site and tell me if this will have the same effect as wrapping lots of thin copper insulated wire on an iron nail or bar. PLEASE!!!

[CraigD]

I have also gone to this site Tubular Electromagnet E-66-38 Magnetic Sensor Systems

can somebody please go to this site and tell me if this will have the same effect as wrapping lots of thin copper insulated wire on an iron nail or bar. PLEASE!!!

This “how do I make an electromagnet” page describes and has photos of what I’ve been suggesting. Note that you don’t have to follow it exactly – your nail could be a bit smaller or larger (they suggest a 6” nail), and you’re planning to use a 9V battery instead of “one or more [1.5V] D-cells batteries”.

 

I wouldn’t worry about the electomagnets being too strong and pulling the car down – if they are, you can just remove some windings to reduce their strength.

[CraigD]

… does the copper wire or electromagnet attract the train?

Technically, neither. The electromagnet creates a magnetic field, as does the magnetic materials in the train. The fields are what create the forces that make things move.

 

What’s really happening can get very deep, but it’s accurate to say magnetic force is due to the interaction of fermions (matter, like nails and magnets) with bosons (in the case of magnetic force, photons). You can easily spend months or years studying the physics of even the most simple-seeming mechanical things. I highly recommend it.

[CraigD]

hey craig can you please go to RadioShack- Audio/Video Electronics, MP3, LCD TVs, GPS, Digital Cameras, DVD Players, Accessories

and recommend me a switch for the electromagnet please. thanks

This center-off DPDT toggle switch does practically everything a switch can do, but at $3.49 each, would increase the cost of your project considerable, especially if you have a lot of electromagnets in your final design. The slide switches you posted earlier don’t have a center-off position, but are much cheaper.

 

Keep in mind that you can make lots of simple, low-power switches from scratch, using various arrangements of conductors like sheet steel, for a few dollars and a bit of craftiness and time.

[CraigD]

how do i know that the electromagnets are going to push the train front and not backwards towards the station cause' the magnetic field is in a circular motion?

Because your train car it itself a magnet, the electromagnet will attract it if unlike pole of the car and the electromagnet are pointed toward one another, repelled from it if like ones are. If the car was not a magnet, just a magnetic material, it would be attracted to either pole of the electromagnet.

 

Keep in mind that, although it’s traditional to draw magnetic fields using arrows (eg: GSU’s “HyperPhysics” “Iron Core Solenoid”), this doesn’t mean they’re in “circular motion”. By convention, the arrows point in the direction that the N pole of a compass placed at that location in the field would point.

 

Time to get building, I think. Many questions raised in this thread are better answered by hands-on experience than words.