I saw this on the TV show Beakman's World and I was very impressed
that you could actually build a working electric motor with so few parts.
I built one and brought it to work where it was a big hit with all the
engineers around here. This writeup was for a friend of mine who wanted
instructions that his son could follow for a science fair project. So,
if you missed the show, here's how to build one. If you are using a text
only browser, you can click on the "Figure" links to download
the drawing s (GIF files). BTW, my friend's son won second place in the
school's science fair.
BTW, I am not Beakman, nor do I have anything to do with
the show. I am just a fan...
To contact me directly: Chris Palmer
'I play "Lester," the guy in the rat suit on "Beakman's
World," and I'm delighted to see my personal favorite Beakman experiment
so faithfully rendered and explained on the Web. Thanks!'
Mark "Lester" Ritts, Los Angeles, California
Visitors to this page since January, 1998.
I had around 80,000 when my old counter broke last September, so you can probably add around 90-100K to the above counter.
How It Works
- 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 plastic
- 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 illustration below:
Figure 1: M1.gif
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.
Figure 2: M2.gif
- Bend the two paper clips into the following shape (needle-nosed pliers
may be useful here):
Figure 3: M3.gif
- Use the rubber band to hold the loop ends (on the left in the above
drawing) to the terminals of the "D" Cell battery:
Figure 4: M4.gif
- Stick the ceramic magnet on the side of the battery as shown:
Figure 5: M5.gif
- 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 proper position:
Figure 6: M6.gif
- Here is a diagram of the finished motor:
Figure 7: motor.gif
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?
You can get the magnet wire and ceramic magnets at Radio Shack. I think
the wire comes in a pack of three spools of different gauges, you want
to use the medium gauge, not too heavy, but thick enough to hold its shape.
Be sure to bring a fresh (extra) battery to school with the project.
You should include the Beakman's World show in your bibliography.
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Christopher M. Palmer / Intergraph Corporation / firstname.lastname@example.org