Ultra-simple Electric Generator (c)1996 William Beaty 4 - 1cm x 2cm x 5cm ceramic magnet, Radio Shack #64-1877 $ .99 1 - #30 Magnet wire 200ft, Radio Shack # 278-1345 $3.99 1 - Miniature Lamp, 1.5Volt 25mA Radio Shack #272-1139 $1.29 1 - Cardboard strip, 8cm x 30cm 1 - Large nail, 8cm long or more Misc. - Knife or sandpaper to strip the wires Misc. - tape Optional: hand drill or electric drill This AC generator is made up of a hollow-ended cardboard box with a nail through the center, many turns of wire wound around the box, and four magnets clamped around the nail. When the nail and magnets are spun fast by hand, the little light bulb lights up dimly. First make the hollow-ended box. Score the cardboard strip like so: ___________________________________________________________________ | 8cm | 3.5cm | 8cm | 3cm | 7.5cm | | | | | | | | | | | | | | | | | | | |8 | | | | | |cm | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |________________|________|_________________|_______|_______________| _____8_________ _|______________ \ |\ 7 | \ 3.5 |3\ | \ | \_____________|___\ | | 8 | | | | | | | | | | Fold it like this and tape | | | it securely. | | | | | | | | | | | | \ | | \|__________________| _______________ _|______________ \ |\ | \ | \ | \ | \_____________|___\ | | | Use the nail to poke a hole perfectly | | | straight through the center of the | | | box, going through both sides and all | | (hole) | three layers of cardboard. Then pull | | | the nail out and use it to widen all | | O | the holes slightly, so when you put | | | the nail back through, it will be a | | | bit loose and able to spin. | | | \ | | \|__________________| Pick the spool of number-30 magnet wire from _______________ the kit of spools. This is the thinnest. _|______________ \ Tape one end of the number-30 magnet wire |\ | \ to the side of the box, then wind all of | \ | \ the wire onto the box as shown. It's OK | \_____________|___\ to cover up the nail hole. Pull the taped | | | end of the wire out, then tape down both \ | | of the wires so you have about 10cm \\ | | of wire sticking out. \\\====================| \\\====================/___ |\\====================/ \ -----+-\====================/ \ / | ==================== \ / | | | \ Use sandpaper or the edge of a | \ | | | knife to scrape the thin plastic | \|__________________| | coating off 2cm of the wire ends. | Remove every bit of red coating, so the wire ends are coppery. _______________ _|______________ \ |\ | \ | \ | \ | \_____________|___\ Spread the wire away from the | | | nail hole and tape it in place. \ | | Stick the nail back through the \\ | | holes and make sure it can spin. \\\====================| Take your four magnets, stick \\\========---=========/___ them face to face in two pairs, |\\========(\\)========/ \ Then stick the two pairs inside -----+-\===========(_)======/ \ the box and on either side of the / | ==================== | nail so they grab the nail. Push / | | | | them around until they are some- \ | | | what balanced and even, then spin \|__________________| | the nail and see if they turn freely. If you wish, you can stick 2cm squares of cardboard between the magnets to straighten them, and tape the magnets so they don't move around on the nail. _____ magnets |_____| _____________ |_____| |_____________| 2 magnets =================|| NAIL |_____________| |_____| ______O______ |_____| |_____________| 2 magnets |_____________| SIDE VIEW OF THE NAIL AND MAGNETS VIEW FROM THE END Twist the scraped end of each generator wire securely around each wire from the small light bulb. One generator wire goes to one light bulb wire, the other generator wire goes to the other light bulb wire, and the two wire connections should not touch together. Spin the magnet REALLY fast and the bulb will light dimly. If it doesn't work, try spinning it in a dark room so you don't miss the dim glow. If needed, adjust the position of the magnets so they don't hit or scrap the cardboard. This thing has to spin *fast*, and if the magnets whack the cardboard and stop, you won't see any light. Once you get it to work, try clamping the point of the nail into the chuck of a hand-drill. Spin the magnets fast with the drill and the bulb will light brightly. Don't go too fast or you'll burn out the bulb, or fling magnets all over the room. Note: your generator produces Alternating Current, not Direct Current. The output voltage is about 2 volts max, so there is no shock hazard at all. HOW IT WORKS When a circle of wire surrounds a magnetic field, and the magnetic field then changes, a circular voltage appears and forces the movable charges in the wire to rotate around the circle. In other words, moving magnets create current in closed circles of wire. This is a basic law of physics, and is the basis of electric generators. OTHER THINGS TO TRY: Disconnect one wire from the light bulb. Spin the magnet. While still spinning the magnet, have a friend touch the wires together so the bulb lights up again. Is the nail still as easy to spin? Keep spinning the magnet while your friend connects and disconnects the bulb. Feel any difference in how hard you must spin the nail? SO WHAT? When you crank the generator and make the lightbulb turn on, you are working against electrical friction in order to create the heat and light. You can FEEL the work you do, because when you connect and disconnect the bulb, it gets harder and easier to crank the generator. Think of it like this. If you rub your hands together lightly, the skin stays cool, but if you rub your hands together hard, your skin gets hot. It's hard to heat skin, it takes work. And it's hard to heat the lightbulb filament, it takes work. You twist the generator shaft, the generator pushes the wire's charge slowly through the tiny filament, and if you don't keep spinning the magnet, the magnet will be slowed quickly. FEEL AN ELECTRON When your hand spins the magnet, you can feel the extra work it takes to light the bulb. This happens because your hand is connected to the flowing charge in the bulb, and when you push on it, you can feel it push back on you! Your hand twists the nail, the nail spins the magnet, the magnet pushes the invisible magnetic fields, the fields push the movable charges, the charges flow slowly through the light bulb filament, and the tiny filament causes friction against the flow of charge and heats up. But then the reverse happens! The charge can't move much because of the tiny filament, so it resists the pressure from the magnetic fields, which in turn resist the pressure from the magnet, which resists the twisting pressure from the nail, which resists the twisting pressure from your fingers. So, in a very real way, you can FEEL the electrons in the light bulb filament. When you push them, you can FEEL their reluctance to move through the narrow filament! A CHALLENGE: there is a simple way to convert your generator into a motor. It involves putting some insulating paint on part of the nail, then using a 6V battery and using the generator wires as "brushes" touching the nail. Can you discover the trick? WARNING: Keep the magnets away from computers, disks, color TV sets, and wallets and purses containing credit cards. Try this: Keep the generator far from your color TV, turn on the TV, start spining the nail so the magnet is spinning fast, then bring the generator about 2ft away from the TV screen. DON'T BRING IT CLOSER!!! Keep spinning the magnets, and you'll see a cool wobbling effect in the TV picture, along with some color changes. The field from the magnet is bending the electron beam that paints the picture on the screen. Be careful, if you bring the magnet about 15cm away, the iron sheet inside the TV picture tube will become magnetized and the distorted colors will be permanent. DEBUGGING If the generator refuses to work, inspect the place where you twisted the wires together. The generator wire has a very thin red plastic coating, and you must clean all of it off the wire ends before twisting them to the light bulb wires. If there is plastic between the metal of the generator wire and the light bulb wire, the circuit will be "open" and no charge will flow. Don't substitute the magnets with a different type. Don't use a different kind of light bulb. Don't use fewer magnets. Weaker magnets may work, but you won't be able to spin them fast enough by hand, and a motor will be required. The generator can be improved by using more turns of wire. You used only the spool of #30 wire. With more wire, the magnets don't have to spin as fast to light the bulb. Connect the thinnest of the remaining spools of wire to the wire that's there, making sure to scrape the wire ends well clean before twisting them together. Make sure to wind the extra wire in the same direction as the rest of the coil. Mail me at: billb a eskimo com