R
S
properly and the magnets are placed correctly with no wobble. Sometimes you can
coax a motor into running by moving the light
rhythmically and getting it to rotate. You can
also gently spin the motor to get it started. Be
careful not to spin it too fast, or it may jump
out of the magnetic field and break.
The stator magnets provide a stationary
force that the motor turns against. Your motor
may turn without them, but the fastest-run-ning motors I’ve seen used stators.
reconnect it to the opposite cell.
Reversed polarity — If everything above
is correct, and the rotor still just wobbles back
and forth in the light, try this technique. Neatly
cut one pair of coil wires from one pair of cells.
Re-sand the ends of the wires, then solder
them onto the cell leads opposite from the
leads they were on originally. This changes the
direction of the electricity flowing through that
particular coil. If your problem was reversed
polarity, this should fix it.
13. Troubleshoot the motor.
Balance is a common problem. Remove the
stator magnets, then turn the rotor ½ turn
and let go (don’t spin it). If it rotates back to
its original position instead of rotating forward,
you can add weight to the highest part of the
circle. Try bits of brass or solder. Don’t add
nails or other steel weights, because they’re
made with iron, attractive to magnets.
Magnets must be accurately placed. If
they can wobble out of position, they will. If
needed, neatly tape the base magnets to keep
them aligned straight up and down. Make sure
all South poles are facing inward. If needed,
add tape to the bushings to keep the rotor
magnets from wobbling. Again, the front rotor
magnet is centered over the frontmost base
magnet, and the rear rotor magnet is centered
over the rear pair of base magnets.
Solar cells — Make sure you have continuity between each pair of opposite cells, and
not between adjacent cells. If your continuity
is off, you may have to rewire the connections.
If a cell is connected to an adjacent cell, then
14. Show off your Mendocino Motor!
When I show the Mendocino Motor to electrical engineers or physics teachers, I have fun
hearing them think out loud about how
it works.
Place your Mendocino Motor in a sunny
window, and you’ll see it start up when the
sunlight is bright enough, and slow to a stop
when the day fades. Put it on your desk and
watch it turn in the light of your lamp as you
work. Try different types of bulbs for differing
results in speed.
The Mendocino Motor has little torque or
turning power, so it’s a challenge to harness
its motion for other uses. You could fashion a
fan on the rotor axle to move some air. (Stick
more magnets onto the stators to increase
torque.) What other uses can you think of? ;
MAKE contributor Chris Connors is a teacher who loves
to learn with curious people who are interested in inventing
the future. His students have made hundreds of Mendocino
Motors over the years.
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