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How to Make an Electricity Generator for a Model Windmill

A model wind turbine that will spin when subjected to the air flow from an electric fan is a fairly simple and popular science fair project. Testing various turbine designs to find out which one spins fastest at a certain fan speed is a good way to learn about alternative energy sources. However, the project is much more educational and impressive if you build a turbine that can actually generate enough electricity to operate an electrical component such as a light bulb. You can simply attach your turbine to a small DC motor to generate current, but it will operate at a very low efficiency and require a diode to prevent the battery your turbine is charging from spinning the motor in the opposite direction. The best solution is to build your own permanent magnet alternator to generate the electricity.

Things You'll Need

2 coffee can lids
Box cutter or hobby knife
2 small bearings
Superglue or silicon adhesive
10 disc-shaped magnets
Protractor
Uninsulated wire
Sewing machine bobbin
Small bolt with nut and washers
Lantern battery
Multimeter

Instructions

- 1
  Cut a hole in the center of two plastic coffee can lids just large enough for a small bearing. Bearings from skateboard or roller skate wheels work well. Insert the bearings into the holes. Glue them into place using super glue or silicone adhesive.
- 2
  Glue the magnets in a ring at the outer edge of one of the coffee can lids using super glue. The magnets should be glued on the side opposite the lip of the lid and need to be evenly spaced. Mark the locations of the magnets using a protractor or degree wheel. Since you are using 10 magnets, they will need to be evenly spaced 36 degrees around the edge of the wheel. The polarity of the magnets will need to be alternated, so that each magnet you glue with the north pole facing up needs to have two neighbors with the south pole facing up.
- 3
  Wrap a length of uninsulated thin wire tightly around a sewing machine bobbin. To make a good coil, you will need to wrap it about 400 times around the bobbin in as tight a coil as possible. Both coils should have the same number of turns, so keep careful count. When you have reached 400 turns, twist the wire ends together and drip super glue into the coils to hold the wires in place. When the super glue has dried, detach the top of the bobbin and slide off the coil. Repeat the procedure to make a second coil.
- 4
  Place the second coffee can lid on top of the first, lining up the edges as closely as possible. The magnet side of the first coffee can lid should be facing upward, and the lips of the lids should be facing away from one another. Glue the coils to the second coffee can lid so that they are perfectly centered over two magnets on the opposite side of the ring from one another.
- 5
  Connect the two lids with a small bolt just large enough to pass through the center of the bearings. Place three washers in between the coffee can lids and secure the bolt with a nut. Apply a bead of super glue to the head of the bolt, which needs to be on the same side of the lids as the coils. When the glue dries, you should be able to hold the lid with the coils stationary and spin the lid with the magnets.
- 6
  Attach the shaft of your wind turbine to the coffee can lid holding the magnets by gluing a small nut to the end of the shaft and the bearing on the coffee can lid. Glue the coffee can lid holding the coils to the wind turbine's tower.
- 7
  Connect the wire ends of your coils to the positive and negative terminals of a lantern battery. Check the charge of the battery using an electrical multimeter and run the turbine for five to 10 minutes. Check the charge again. If there is no change, swap the wires to the opposite terminals.

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