An alternator can be built into a power generating wind turbine with lightweight parts and make enough electricity for a moderate home. By linking the cyclical motion of the homemade blades to the rotary pulley of the alternator, electricity can be harnessed from the wind. The average backyard builder can make a wind turbine out of an alternator in about three hours.
Remove the gears from the bike wheel by turning the axle nut counterclockwise, or pulling the axle quick-release handle. Leave the largest gear on the axle, and tighten the axle nut.
Affix the automotive pulley wheel to the large gear on the bike wheel, tack welding or using bolts and nuts to secure it. The pulley should match the pulley on the alternator, and a single belt pulley is recommended. Serpentine systems use thicker, grooved pulleys that don't work as well in this application.
Cut the sheet metal into sections four inches wide and four feet long, using the metal snips. This will result in nine long strips of sheet metal. Bend the strips by hand longways, creating a ten to fifteen degree difference from one end to the other. The strips should be bent clockwise, but the direction will depend on the position of the alternator. Thinner metal will have a harder time holding the warped shape, thicker metal might be too heavy for the wind conditions.
Secure all nine of the homemade propeller blades (props) to the bike wheel, on the opposite side of the gear/pulley. They can be bolted or screwed to the spokes of the wheel, the hub, and the outer edge. They should not be secured to the axle, which needs to spin freely. The props should all be aligned with one another, going in the same direction.
Secure the axle to a stand or mount by bolting it directly with the axle nut, or welding it to the mount. Mounts can vary, but a common one for this design is a rooftop satellite dish mount. These can be extended and used to mount the axle and alternator by adding a section of steel pole to the base, then drilling holes for the equipment onto the pole.
Mount the alternator underneath the wheel's pulley, lining up the pulleys evenly. Place the belt over both pulleys, and make adjustments to the mount so that there is a 1/2" of play in the belt. When wind strikes the props, it will spin the wheel, which in turn spins the pulley, belt and alternator. Most domestic alternators have internal voltage regulators, which protects against overload. Tap the primary alternator output bolt (red wire) for up to 100 amps of 12-volt electricity, connecting the alternator's body bolt for a ground (negative power coupling).
Add a vane, if necessary, to point the props into the wind by cutting a section of sheet metal and placing it vertically behind the wheel. It can attach to the mount, and the mount can be modified to use a bicycle wheel bearing to turn easily. The addition of a small, horizontal rod can place the vane far enough back to catch the wind direction and turn the props into the wind. This usually requires as much technical skill as building the entire apparatus, and the wind turbine will function perfectly fine without it.
Use more props for more power, until the weight exceeds the gains.
Use gloves when handling sheet metal, and use caution when working with electrical equipment.