A flashlight is only useful if it has power to operate. No battery or a dead battery can be more than a small hassle when fumbling about in the dark. In order to ensure that there's always light available, you can create your own flashlight that's quickly powered with only a few shakes of the flashlight body. Using Faraday's law of induction, a few magnets inside a coiled wire will provide you with all the charge you need.
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The material components for a shake flashlight are fairly inexpensive and most can be found in the home or bought at a local electronics and hardware store. You'll need an old flashlight, a plastic tube that fits snugly inside the flashlight, thin enameled copper wire, two pieces of heavy gauge wire, two pieces of silicone rubber about 1/4 inches thick, two pieces of insulated wires, a 5.5 V, 1F electrolytic capacitor, an on-off switch, a graetz circuit, an LED diode and a neodymium magnet. The only tools you'll need are a soldering iron, wire cutters and a drill.
Fit the plastic tube into the flashlight, cutting it to size so it can be contained fully within the flashlight body. Take your copper coil and roll it around the plastic tube. You'll want to make the coil winding about the same length as the magnet you're using, rolling so that it centers at the center of the tube. Wind the copper wire in one direction only. You should create multiple layers of wiring so once you reach the end of your coiled size go back to the starting point and begin again on a new layer. This will take awhile as you should continue until you've completed about 1,500 turns of the wire. Leave the ends of the coil free for later connection.
After completing the coiling you'll need to close the end of the tube to prevent the magnet from slipping out when you shake it. Drill four holes in the tube ends then slip a piece of heavy gauge wire through one side to close off that end. Cut a piece of rubber to fit snugly in the end of the tube, then push down onto the wire end. This rubber should keep the magnet from escaping the tube as well as cut down on the noise when you shake the flashlight. Place the magnet into your tune then repeat the wire and rubber step on the other end of the tube.
Solder the insulated wires to the LED and replace the old flashlight bulb with it. Solder the gratz circuit to the electrolytic capacitor, paying attention to match the positive and negative leads. Then solder the ends of your coil to the gratz circuit. Now solder a single insulated wire directly from your lead to the gratz, and a second insulated wire to the other lead from the gratz for later use with the switch.
Drill holes into the flashlight body under the screw top area. Place everything inside the flashlight body except the switch, and the two remaining loose wires, one from the gratz and the other from the led. Run those two wires through the newly drilled holes and attach to the on-off switch. Tape the switch to the outside of the flashlight body before attaching the flashlight top.
After you've assembled the flashlight all that's left is the shaking. By shaking the flashlight you run the magnet within the coils, creating electricity that is stored in the capacitor. Once enough charge is built you can flip the switch and you'll have light.