NOTICE: We have
recently updated this instruction page. Please report any errors
or ambiguity to
info@MiniScience.com or to (973)777-3113.
Making a simple electric motor
is an educational activity that may also be tried as school
project or science project. With this project students can learn
and demonstrate conversion of electrical energy to mechanical
energy. In this simple motor you will use a 1.5-volt battery.
Batteries offer a one directional flow of electricity also known
as DC or Direct Current. That is why this motor is really a
simple DC motor.
List of materials
The main components of a simple DC
motor are a piece of magnet wire and a small magnet. Almost any
type of magnet and any type of magnet wire will work fine. All
other components are optional and may easily be substituted by
other materials. Use the links and images in this page to see
how others make their own simple DC motors. This special design
of DC motor is well fitted for school projects.
Materials
include:
1. Battery Holder
2. Ceramic Disk Magnet
3. Magnet Wire
4. Safety Pins
5. Screws
6. Wood Block
Introduction
Electric motors are everywhere; even your computer has electric
motors to power its cooling fans and hard disks. Building a simple
DC electric motor is a great way to learn how they work, and it's
really fun to watch your creation spin.
Objective
The objective of this project is to build a simple electric motor
from scratch.
How to make?
Start by winding the armature, the part of the motor
that moves. To make the armature nice and round, wind it on a
cylindrical form, such as a pipe or a small AA
battery. The diameter is not critical, but should be related to the
wire size. Thin wire requires a small form, thick wire requires a
larger form. For best results, the diameter of the coil must be the
same as the diameter of the magnet you are using.
Leaving a couple of inches of wire free at
each end, wind
6 to 9
turns around the cylinder form. Don't try to be neat, a little
randomness will help the bundle keep its shape better.
Now carefully pull the coil off of the form, holding the wire so
it doesn't spring out of shape.
To make the coil hold its
shape permanently, twist the free ends and wrap one free end of the wire around the
coil a couple of times, then pass it through and across the loop
and wrap a few turns in the opposite side. Make sure that the new binding turns
are exactly opposite each other, so the coil can turn easily on
the axis formed by the two free ends of wire, like a wheel.
If this method of holding the coil together is too difficult,
feel free to use scotch tape or electrical tape to do the job. The
important thing is to keep the coil together, and to have the two
ends of the wire anchored well, and aligned in a straight line, so
they form a good axle.
Now is where the secret trick comes in, the thing that makes the
motor work. It is a secret trick because it is a small and subtle
thing, and is very hard to see when the motor is running. Even
people who know a lot about motors may be puzzled until they examine
it closely and find the secret.
Hold the coil at the edge of a table, so the coil is
straight up
and down (not flat on the table), and one of the free wire ends is
lying flat on the table. With a sharp knife, remove the top half of
the insulation from the free wire end. Be careful to leave the
bottom half of the wire with the enamel insulation intact. The top
half of the wire will be shiny bare copper, and the bottom half will
be the color of the insulation.
Do the same thing to the other free wire end, making sure that
the shiny bare copper side is facing up on both wire ends.
The idea behind the trick is that the armature is going to rest
on two supports made of bare wire safety pins. These supports will be attached
to each end of the battery, so electricity can flow from one support
into the armature and back through the other support to the battery.
But this will only happen when the bare half of the wire is facing
down, touching the supports. When the bare copper half is facing up,
the insulated half is touching the supports, and no current can
flow.
The next step is to prepare the axle supports.
Use a pair of pliers to bend two safety pins from the middle. The
safety pins can conduct electricity to the armature while the loops of wire
on the safety pin can hold it up.
The base for this motor will be a
wood block. It
makes a nice base because it is heavy, stable and looks good
for presentation in classroom or science fair. The wood block is
large enough to hold the battery as well.
Use screws to mount the bent safety
pins on the wood block so that the loops are faced to each other and
about 1 inch apart.
Attach the wires from battery holder to
the supports (bent safety pins)
Place the safety pins so the rings are just
far enough apart for the armature to spin freely. Insert the screws
through the lock of the safety pins into the wood. Swing the safety pins apart a
little and insert the armature into both rings, then swing them back
so they are close to the coil, but not touching it.
Insert the battery into the holder. Place the magnet on top of
the wood block just underneath the coil. Make sure the coil can
still spin freely, and that it just misses the magnet.
In some images you may see that there is a toothpick
or plastic strip stuck in between the battery
and the electrical contact in the holder. This is the on/off switch.
Remove it to allow electricity to flow into the motor, and
replace it when you want to stop the motor and save the
battery.
Spin the armature gently to get the motor started. If it doesn't
start, try spinning it in the other direction. The motor will only
spin in one direction.
If the motor still doesn't start, carefully check all the
electrical connections. Is the battery connected so one support
touches the positive end of the battery, and the other touches the
negative end? Is the bare copper half of the armature wire touching
the support wires at the bottom, and only at the bottom? Is the
armature freely spinning?
If all these things are correct, your little motor should be
spinning around at a pretty fast rate. Try holding it upside down.
The motor should spin in the opposite direction if the magnet is on
top instead of on the bottom. Try turning the magnet upside down and
see which direction the motor spins. If you want a motor that has
the magnet on the side instead of the top or bottom, you can simply
make a new armature, but this time lay the coil flat on the table
when you scrape the insulation off of the top half of the free wire
ends.
Terms, Concepts and Questions to Start Background Research
To do an experiment in this area, you should do research that
enables you to understand the following terms and concepts:
Another way of preparing the
armature is wrapping the two ends of the wire in two
opposite sides of the loop. In this way, one half of loop
will have more wire than the other half and it will become
heavier. This will change the balance and make it harder for
the armature to spin. In this case you can move one of the
ties slightly toward the heavier side to gain the balance
again.
It is important for the
loop to be balanced and spin freely around its axle.
It is not necessary, but some
people wrap a couple turns around
these binding turns as well, threading the wire into the space
between the large coil and the small coils that hold it together.
This makes for a neat, tight package, as in the photo below:
If you don't have this
kit, you can order it now! It is available both as a single
pack and class pack. Kit content may be different from the
images shown in this page.
