Engineering > Electromagnetics > Simple Maglev Train

Site: http://amasci.com/maglev/train.html

Grade Category: High School

Subject Category: Engineering

Sub Category: Electromagnetics

(c)1996 W. Beaty

Lots of people have emailed me about building some sort of maglev train as a science project. Here are my suggestions.

A truely levitated maglev train is a very complex device. Permanent magnets alone cannot suspend a train car. You'd also need coils, amplifiers, and negative feedback too. I'd only recommend the coils/sensors approach if you are a college student or fairly advanced highschooler.

However, there's a way to make a simple permanent-magnet maglev train. Instead of using coils and electronics, we just put guide rails on the sides of the track. The guide rails will lightly touch your train and keep it centered. Because real science involves striking out into the unknown, I'm not going to give detailed plans here. Just enough info to get you started.

The lifter-rails under your train will be small square ceramic magnets. Radio Shack stores in the US sell a good type, the 1" x 3/4" square with a hole in the center. Each foot of train track will require 32 of these magnets. Less expensive magnets are available from All Electronics, but I haven't tried these (see links at end of article).

First mark one pole on all of your magnets so you later can lay them down with the same pole facing upwards. To do this, stick your magnets all together in one big long stack. Now use a permanent marker to make an "X" on flat face of one end of the stack. Pull the marked magnet off the stack, make an "X" on the next one, etc., until you're out of magnets. Mark every single one on the same side.

Before building an entire huge track, make a "test bed" about one foot long. For a base, you can use cardboard or wood. Don't use iron or steel of course. You'll be lining up your magnets side by side in long rows. One way to do this is to stick them to a strip of duct tape, then lay the strip down on the cardboard or wood and rub the tape down to hold the magnets underneath. Position each magnet carefully on the tape so the row is very straight. Make two parallel rows of magnets with about 5cm of space between the rows. Make sure the rows are perfectly parallel. It might help to measure with a ruler and draw lines on the base first.

For a temporary "car", cut out a square of cardboard 9cm by 15cm . Tape four magnets to the corners, flipping the magnets correctly so they will repel from the tracks when the cardboard is layed down. Position the magnets on the cardboard so they will be exactly over the magnets on the track.

If you place your cardboard "car" on your magnet track, you'll find that it will twist or flip over and fall, and will not hover. But if you gently hold it by its sides, you can keep it floating in position. Does this give you ideas? What if you place one long board on each side of your track? The "car" will touch the two boards and will stop slipping sideways, but the boards will not stop the car from slipping down the track.

                   MAGLEV TRACK,

    board          VIEW FROM THE END         board

    ____                                      ____

   |    |                                    |    |

   |    |                                    |    |

   |    |        magnet         magnet       |    |

   |    |        row            row          |    |

   |    |     _____                _____     |    |



                      wood or cardboard


               CARDBOARD CAR IN PLACE  

    ____       (end view)                     ____

   |    |                                    |    |

   |    |                                    |    |

   |    | __________________________________ |    |

   |    ||__________________________________||    |

   |    |    |_____|              |_____|    |    |

   |    |     _____                _____     |    |



Once you get this part working, you can build a much longer track. You can build a real car too, one that looks like a train, although you'll have to find very lightweight construction materials. You can try thinking up ways to reduce the friction with the side rails. Maybe try aluminum angle strips instead of wood, or sand the wood smooth and paint it with something hard and shiny.

But how can you drive your train forward? I don't know. You'll have to think of something. There are only two ways to move a hovering object. One is to grab something on the ground and pull or push forwards (this includes tilting the rail to become a ramp; using gravity to pull the car forwards.) The other way is to force something out the back, which drives the car forward. Use the car to launch marbles rolling down a tiny ramp? Use a propellor? Squirt water? Rocket engine?


The Goldenrod Paper Secret was passed on to me around 1987 by Dr. 
      Roy Gould of the Harvard CFA, who got it from his brother, an R&D 
      chemist in NYC, who heard about it as the "secret" traveled from 
      chem lab to chem lab  across the country.  I wrote up this paper and 
      posted it on the web around 1995.  Since then it has spread all over 
      the place!
         TAKE NOTE:
      On 4/98 somebody bought some Astrobrights Goldenrod paper which
      DID NOT WORK, it did not change colors.  Therefore, perhaps it is
      time to run out and buy reams of "goldenrod" quickly, before the
      "good" kind is entirely replaced with the "doesn't work" kind.
      Also, take some baking soda with you to the stationery store, so you 
      can test the paper (the "good" kind will turn red when moist baking
      soda is rubbed on it.)
      The "good" kind is Astrobrights Galaxy Gold WAAB57A, from Wausau Papers.
      Goldenrod paper is available at Teachersource
THE "GOLDENROD PAPER" SECRET                (c)1996 William J. Beaty
Office supply stores and Kinko's copy centers sell a type of paper called
Astrobrights(tm) Galaxy Gold.  It's "goldenrod" in color, sort of a
yellow/orange. Big deal.  However, IF ALKALINE SUBSTANCES HIT IT, IT TURNS
MAGENTA!  Spray it with Windex, and it instantly turns bright red!  Cool!!
Astrobrights Galaxy Gold paper is the worlds largest acid/base indicator
strip.  Dip it in a base solution (like ammonia cleaner, baking soda 
in water, etc.) and it turns bright red.  Dip it in acid (vinegar, lemon
juice, etc.) and it turns yellow again. 
  (Note: there are other brands of goldenrod which do not work.  If in 
  doubt, wet a sample of the paper with ammonia glass cleaner.  Kinko's 
  usually has bottles of Windex around)
The fact that an 8.5 x 11 sheet of goldenrod is enormously larger than 
your typical acid/base litumus paper test strip makes numerous classroom
demonstrations possible that never could be done before.
Cut it into strips, dip it in acid or base.  It turns colors.  duh.
Dip it in base so it turns red, then dry it out.  This gives you an
acid-indicating paper which starts out red  ...and turns yellow in acid.
Put dilute vinegar in one jar, baking-soda solution in another.  (Baking
soda dissolves better in warm water.) Use paintbrushes to paint on the
goldenrod.  Baking soda solution turns the yellow paper red.  The vinegar
solution turns previously-reddened paper yellow.  Paint an invisible
picture with vinegar on yellow goldenrod, let it dry, then spray it with
baking soda solution.  It turns red everywhere except the places having
Draw "invisible" patterns or messages on the paper with rubber cement,
diluted Elmer's glue, transparent tape, etc., then spray it with alkaline
solution.  The paper turns red except where your drawing has sealed it. 
Yellow artworks on red background appears.
Wet a strip of previously-reddened goldenrod, then lower the strip into a
half-full glass of carbonated beverage.  Don't let the strip touch the
liquid.  The strip turns orange as the transparent pool of carbon dioxide
forms carbonic acid in the wet paper.  This lets you "see" the invisible 
pool of CO2 gas which fills the cup.  (Only works in a draft-free room,
where the CO2 gas remains atop the cola.)
Dust your hands with baking soda. Claim that you have "Alien DNA Test
Paper," and if it turns red, it indicates that you are not human.  Have
your audience put their thumbprints on some wet Goldenrod paper.  Anyone with
baking soda on their fingers (you!) will leave a thumbprint which slowly 
turns red. 
ELECTROLYSIS: wet some goldenrod paper with salt water and place it on a
sheet of aluminum foil.  Use clipleads to connect the positive terminal of
a 6v or 9v battery to the foil.  Connect a wire to the negative battery
terminal.  Now drag the negative wire across the wet goldenrod, and it
turns red.  Write with electrochemistry!  If you reverse the polarity of
the battery, you can erase your red drawings.  If you replace the
goldenrod with previously-reddened paper, the reversed battery connections
let you draw in yellow on a red background.  (the positive plate creates
acidic solution, while the negative plate makes alkaline.)
MY OLD ACID RAIN DEMO: Wet the inside of a glass jar.  Light a match, blow
it out, then collect the smoke inside the upside-down jar.  After awhile
the drops of water collect nasty combustion products from the smoke and
become acidic.  Touch the drops to previously reddened goldenrod paper,
and it turns yellow, indicating acid.  Instant acid rain!  And might you
think twice about smoking cigarettes and putting acid in your lungs?  I
thought up this one while working at the Museum of Science in Boston. 
   NOTE: Young kids shouldn't perform the following demonstrations.
   Ammonia is somewhat toxic, is nasty if inhaled, and is dangerous
   if splashed in eyes.  Adult supervision only.  Wear safety goggles. 
Wet some goldenrod paper, then drip some ammonia-based cleaner upon it. 
Notice that the red drops have red haloes around them?  Just the ammonia
fumes alone can turn the paper red. 
Wet some goldenrod paper.  Put some ice cubes in a jar, then pour in a
little ammonia and wait for some cold ammonia gas to build up.  Carefully
pour the transparent ammonia gas over the wet goldenrod paper, and it
flares red.  Dip a wet strip of un-reddened goldenrod into the
seemingly-empty jar, and you'll discover the depth of the pool of cold
ammonia gas.  Make wet marks on dry goldenrod, and when cold ammonia gas
is poured over it, the wet marks turn red.  (Don't leave the jar of ice
cubes sitting around, dump it out so that passersby can't take a sip from
your glass of "icewater.") 
Use a smoke-ring box to shoot invisible ammonia "smoke rings" at wet 
goldenrod paper.  Little red puffs appear where they hit.
Freak out Kinko's Copies employees by buying one sheet of goldenrod,
asking for the bottle of glass cleaner, then yelling "look!" while
spraying the paper with the ammonia-based cleaner.  But be warned, I've
been doing this for awhile, so the secret is spreading from Kinko's to
Kinko's like a mind-virus.  They may already know about it