Electric generators are devices that use alternating magnetic fields to create current through a circuit. While large-scale ones are expensive and complex to build, you can still make a small one quite easily. All you have to do is prepare a structure that will hold the magnet and the cable, wind the latter to create a coil and connect it to an electrical device; finally, you have to glue the magnet to a rotating pin. The procedure described in the article is also perfect for teaching electromagnetic properties or as a science project.
Steps
Part 1 of 3: Building the Structure
Step 1. Cut the cardboard
This material forms the frame and supports your modest generator. Use a ruler to measure a strip 8cm wide and 30.4cm long; cut it out with a pair of scissors or a utility knife. Just fold this simple piece to make the structure.
Step 2. Draw the references
Use a ruler to measure the long edge of the strip and make a mark at 8 cm; the second mark should be at 11.5cm and the third at 19.5cm, while the last should be at the 22.7cm mark.
By doing so, divide the strip into 8cm segments, one 3.5cm, another 8cm, one 3.2cm and a final 7.7cm; be careful not to cut such segments
Step 3. Fold the cardboard following the various references
In this way, the strip is transformed into a rectangular structure that will house the components of the electric generator.
Step 4. Thread the metal pin through the frame
Push it into the cardboard, so that it passes through all three segments that are folded in the center; with this trick, you drill a hole in which to leave the metal pin (which you can replace with a large nail).
The pin must not have any special features; any metal rod capable of entering the hole and piercing the structure is fine. The nail you used to make the hole is fine
Part 2 of 3: Creating the Circuit
Step 1. Wrap the copper wire
Make several turns around the cardboard structure using enameled copper wire (30 gauge). Wrap 60m of electrical cable as tightly as possible, leaving 40-45cm free on each end to connect the wire to a multimeter, light bulb or electronic device of your choice; the greater the number of turns, the greater the power generated.
Step 2. Strip the ends of the cable
Use a knife or wire stripping pliers to remove the insulation layer; remove about 2-3 cm from each end of the electric wire, so that you can connect it to the electrical device.
Step 3. Connect the wires to the device
Connect the ends you stripped to a red LED, a small light bulb or other similar element; alternatively, you can decide to join the generator to the probes of an alternating current voltmeter or a multimeter. Remember that you are going to generate a small voltage which is unable to power large electronic tools (like a regular light bulb).
Part 3 of 3: Place the Magnets
Step 1. Glue the magnets
Use high tack hot melt glue or epoxy glue to attach four ceramic magnets to the metal pin; these must remain stationary with respect to the auction. Take care to proceed after inserting the nail into the cardboard structure. Let the adhesive dry for several minutes (you should read the exact times on the product packaging).
For the best results, opt for the ceramic magnets in size 2,5x5x12 cm (you can buy them online for a reasonable price). Glue them so that the north side of two magnets and the south side of the other two are facing the coil
Step 2. Rotate the pin with your fingers
This way, you can make sure that the end of each magnet does not hit the inside of the structure. The elements must rotate freely, but as close as possible to the coils of the copper cable, to maximize the action of the magnetic field on the electrons of the coil.
Step 3. Rotate the pin as quickly as possible
You can wrap some string around the end of the nail and pull it sharply to make the magnets spin; you can also just use your fingers. As the magnets rotate, they generate a small potential difference that allows a 1.5 volt bulb to light up.
