- One 'D' Cell Alkaline Battery
- One Wide Rubber Band
- Two Large Paper Clips
- One Rectangular Ceramic Magnet
- Heavy Gauge Magnet Wire (the kind with red enamel insulation, not
- One Toilet Paper Tube
- Fine Sandpaper
- Optional: Glue, Small Block of Wood for Base
- Starting about 3 inches from the end of the wire, wrap it 7 times
around the toilet paper tube. Remove the tube (you don't need it any
more). Cut the wire, leaving a 3 inch tail opposite the original starting
point. Wrap the two tails around the coil so that the coil is held
together and the two tails extend perpendicular to the coil. See
Note: Be sure to center the two tails on either side of the
coil. Balance is important. You might need to put a drop of glue where the
tail meets the coil to prevent slipping.
- On one tail, use fine sandpaper to completely remove the insulation
from the wire. Leave about 1/4" of insulation on the end and where the
wire meets to coil. On the other tail, lay the coil down flat and lightly
sand off the insulation from the top half of the wire only. Again, leave
1/4" of full insulation on the end and where the wire meets the coil.
- Bend the two paper clips into the following shape (needle-nosed pliers
may be useful here):
- Use the rubber band to hold the loop ends (on the left in the above
drawing) to the terminals of the "D" Cell battery:
- Stick the ceramic magnet on the side of the battery as shown:
- Place the coil in the cradle formed by the right ends of the paper
clips. You may have to give it a gentle push to get it started, but it
should begin to spin rapidly. If it doesn't spin, check to make sure that
all of the insulation has been remove d from the wire ends. If it spins
erratically, make sure that the tails on the coil are centered on the
sides of the coil. Note that the motor is "in phase" only when it is held
horizontally (as shown in the drawing).
- For display, you will probably need to build a small cradle to hold
the motor in the proper position. It might also help to bend the ends of
the coil a bit so that as it slips right or left, the bends keep it in the
- Here is a diagram of the finished motor:
Since this is an existing design, you might want to do some further
experiments to make it more of a Science Fair experiment instead of just a
model. Here are some suggestions:
- Try to adjust the phase angle of the motor so that it will operate in
a vertical position. This involves removing a different area of insulation
from the partially bared tail of the coil.
- Try making different shaped coils and seeing how they work. Is the
circle the best shape? Try squares, ovals, etc. Make a display showing
each of the coils you tried with a short summary of the results underneath
- Try varying the number of turns of wire in the coil. I don't know
where they came up with seven. Does even or odd number of turns matter?
Does the number of turns determine the speed? Again, include the different
coils in the display and describe the results.
- How long can you get the motor to run before it falls off the cradle?
- Turn the coil slowly by hand and feel the magnetic attraction at each
position of the coil. Make drawings showing the different coil positions
and describe how the attractions vary at each position.
- HARD ONES: Can you think of an interesting way of determining the
speed of the motor (in RPM)? Can you make the motor do any work?
I used a used toilet paper roll, but any round form about the same size
will work just fine.
The wire should be enamel coated magnet wire. This is solid copper wire
with a baked on insulation, usually red, although it can be clear.
Uninsulated wire will not work. Wire with rubber or plastic insulation will
not work without some extra work.
If your motor looks like the one in the picture, you are most of the way
there. Study the picture carefully....
If your magnet is dark grey or brown, it is probably a ceramic magnet.
Just about any kind of magnet should work, but it has to be strong (small
refrigerator magnets or those rubbery sheet magnets probably won't work). If
all you have is small magnets, try stacking them together. The large
rectangular magnets from Radio Shack work very well. If your Radio Shack
doesn't carry them (or you don't have a Radio Shack nearby), try your local
hardware store (such as Lowe's or Home Depot), they usually have a large
selection of magnets for doing things like magnetizing tools or hanging
tools on walls. Again, get a strong, relatively flat magnet. Circular
magnets should work.
The sanding of the coils is probably the trickiest part. Reread these
directions and see if the correspond with your understanding of the web page
- Make the coil per the directions.
- Take your sandpaper and sand all of the insulation off of one tail of
the coil (the wire sticking out from the coil). It should be bright and
shiny copper all the way around.
- Now, lay the coil down on something that is safe to sand on. On the
other tail, sand off all of the insulation on the top half of the wire.
When you get through, the wire should be red on one side and copper
colored on the other.
Other things to try:
- Make sure your paper clips are good quality metal and are not covered
with plastic or rubber. Sand them lightly on the surfaces that contact the
battery and on the surfaces that the coil lays on.
- If all else fails, make sure you have a fresh battery -- previous
errors in sanding the coils may have created a short circuit that drained
- Have someone else read the instructions without looking at your
construction -- sometimes a fresh viewpoint can point out problems and