Several years ago we built our own custom made residential wind turbine, used to charge 12vDC batteries. It was made from spare farm machinery parts, components purchased on eBay, and other purchased materials. Pictures of it are shown below.
Structure:
Binzie sits atop a 25' telephone pole and rotates horizontally so that the prop is always facing oncoming wind. The unit is grounded to help protect the windmill and barn from lightning. The actual body, props, tail assembly, and swivel unit weigh around 250 pounds total.
Mechanical details:
The props are constructed of sheet metal around a 1" copper pipe. Each prop is about 53" in length and each assembly consists of a the metal wrapped around and riveted a spine made from a piece of the copper pipe. The three props are then connected to the hub. The face of the hub has three, 3/4" x 18" shafts welded to it (120 degrees apart) where the copper spine of each prop slides over each shaft, and the pitch of each prop can be adjusted via one turnbuckle connected from the base of each prop to the central shaft that extends horizontally to the back side of the structure. The ends of each 18 inch shaft have threaded holes, where a threaded rod is inserted and runs the entire length, inside of each copper spine, so that it exits each spine and then holds each prop on via nut and large washer.
At the back of the structure are two sets of large and small belt pulleys that act as a transmission, and allow 1 complete rotation of the prop to turn an Ametek permanent magnet DC motor (generator) about 8 to 10 revolutions. This translates to a situation of when the prop is turns at 60rpm, the generator turns about 480-600 rpm. The generator begin to produce once movement begins, its output increases with speed.
Extending off of the main windmill structure is a tail constructed of 2" square tube steel and tin. This tail continually swings the main structure to rotate and always face the wind. This ability to rotate comes about as a result of a truck tire hub welded to a 8" piece of well casing that is dropped down over top of the telephone pole. The main windmill structure is fastened to this truck hub.
At the pivot point of the unit, we also mounted a power transfer collar from a silo unloader. This allows us to transfer power over the wiring paths described below, with out having to worry about wires wrapping around the pole as the windmill rotates to face the wind. The power transfer collar consists of three brass rings and a set of brushes that maintain contact with each ring as the unit rotates.
Wiring path for a Permanent Magnet DC motor-generator (current power source):
The generator has a positive and negative wire, and does not require an excitation circuit to begin to produce power. These wires are connected to two 12v lights on the windmill's tail so that it can be known when the windmill is producing power. The wires then also run down to a battery bank at the base of the windmill, with a diode assembly at the base to prevent the battery bank from actually running the permanent magnet motor (generator). To prevent overcharge of the batter bank, we have a NC25A charge controller to divert our electrical load to another power consumer (110v lights) once the battery bank is at full charge.