THINGS YOU NEED: Model airplane propeller about 6" long. Two nails 1" long. Two nails 3" long. Four small nails. Small bar magnet 1" long. Two metals strips 1½" by 4", cut from a tin can. Magnet wire from Experiment 2. Germanium diode type 1N34A (most electronics stores carry this inex- pensive part). Tape. Glue. Soldering iron and solder. Wood block about 3½" by 5".The galvanometer you made in Experiment 2.

     The model wind generator you’re going to make works much like the new “wind turbines” for generating electricity. When the propeller spins, the magnet whizzing past the nail head generates a tiny alternating current (AC) in the coil around the nail. The small germanium diode connected across the two nail terminals converts the AC into DC (directcurrent), which is what we need in this experiment.

     To make the wind generator, begin by wrapping 1000 turns of magnet wire around one of the large nails. The coil should be 2" long, measured from the head end. Leave a few inches of wire for connections. Twist them so they won’t unravel.

     Drive this nail into the center of the wood block. Also drive in the two smaller nails where shown.

     After scraping the enamel insulation off the ends of the coil wires, wrap the bared ends around the nail heads. Then hook the diode across the nails, and make all connections secure by soldering.

     Next, glue the bar magnet to the head of the other large nail. Be sure the magnet is centered on the head and the glue is given plenty of time to set. This will be our propeller shaft.