With two cups, some wire coil, a headphone plug, sticky notes, tissues, and a some magnets, make your own headphones, which will transmit sound from a radio, MP3 player or cell phone.
Step 1: Understanding How a Speaker Works
Speakers are part of our everyday life. They are the ones that produce sound in our electronic devices, like cell phones, radios, TV's, MP3 players, etc. Manufactured speakers have many different components that allow it to produce what we perceive as sound. But in order to understand the basics, it’s important to know about the 3 main parts that help a speaker produce sound.
The 3 Essential parts of any speaker are: Magnet, Voice Coil, and Diaphragm
Magnet – it provides a stationary magnetic field to oppose the electromagnetic field of the voice coil and causes the cone to move inward and outward, which produces sound.
Voice Coil – the voice coil is a coil of wire through which the electrical audio signal flows. The current of the audio alternates, creating an electromagnetic field which is opposed by the magnetic field of the magnet circuit. This causes the voice coil and diaphragm to vibrate and help produce sound.
Diaphragm – it’s a rim of flexible material that vibrates in order to create sound waves. The magnetic suspension created by the voice coil and magnet moves the diaphragm back and forth.
Step 2: Gather Your Materials
28 Gauge Red Coil (the thinner the coil, the better it conducts sound)
½ inch neodymium magnets ( 4 Packets of 3 magnets each )
Plastic cups (2)
1 normal-sized glue stick (Any Brand)
Something to play music (MP3, Computer, Etc)
7” by 5” Piece of Foil (optional)
Marker (Color of your Choice); anything to decorate your speaker (optional)
Soft tissues (2)
Beanie/Headband (something to cover the coils, so the two speakers look like headphones).
Step 3: Making the Speakers (Part One)
1. Gather the cups, magnets, the coil, and any other accessories you might want.
2. Take out the neodymium magnets from the packaging they came. Now, take out the plastic disk between the magnets. Put 3 magnets on top of the cup, and the other 3 on the other side. The magnets should now be fixed in place.
3. Wrap a post it around the glue stick. Remove the note and put some scotch tape to fix it in place. Cut two-thirds of the note and using electrical tape, place it around the magnets. This will act as the base for the speaker’s voice coil (you are welcome to use rubber for the voice coil, but it’s easier to make one out of a post-it note).
4. Cut a length of about 2 feet (about 60 cm) of wire (this is about 40 coils, the more coils, the better the quality of the sound).
Step 4: Burning and Wrapping the Coils
1. The wire is coated, so burn about one inch (2 cm) of the coating on both ends of the wire.
2. Wrap the coated part of the wire around the glue-stick (if you would like to, you could first wrap a post-it, and then wrap the coil around it), leaving 5 inches (13 cm) of wire free at each end.
3. Twist the ends of the wire together several times to fix the coil in place.
4. Remove the coil from the glue-stick (if you wrapped the coil around a post-it, the time-lapsed video above will demonstrate you how to remove it). Then, wrap 2 strips of tape (vertically) in the coil. There should be a loop of wire with two bare ends sticking out from the twisted section.
5. Place the loop of coil around the voice coil (the wrapped post-it), making sure to keep the loose ends of wire free. Be sure that coil is firm and stays in place.
Step 5: Making the Speaker Cup (Cont.)
1. Using a marker or other materials, do any optional decorating to your speaker. If you want to, you could wrap your speaker with some foil/electrical tape.
2. Now, follow the same steps (3-5) to make the other speaker cup.
Step 6: Making the Headphones
1. After you are done with the two speakers, wrap the ends of one coil from one speaker with the ends of the coil of the other speaker (make sure it leaves enough space for the two cups to fit between your head).
2. Next, strip the plastic coating off the end of the aux plug and separate the two strands. Twist the other ends of the two coils together (similar to what you did in the last step; but just make sure to leave at least 2 inches of separated wire after the twisted part), then wrap the each ends of the coils around the holes of the aux plug.
3. Now, use a beanie/headband to cover the coils that will go around your head. Then using electrical tape, cover the rest of the coils so they are not visible.
4. With the two tissues, place each firmly on the open side of each cup, and put some scotch tape on the tissues so they stay in place. The tissues will act as the diaphragms of the speakers.
Step 7: Testing Your Headphones
1. Turn on the MP3 player, CD player, or anything that can play music; plug the aux plug into the source. Make sure to turn the volume louder than you normally would.
2. With both hands, hold the cups to your ear. You should now be able to hear music coming from your cup speaker.
Step 8: What Affects the Quality of the Sound?
The sound in your homemade cup speaker isn’t as good as the sound from a speaker you can buy. But there are various ways to make the sound quality better. The variables that affect the quality of sound are:
- How many times you wrap your coil and how tight and firm the coil is wound.
- The quality and gauge of the coil wire (thinner coil/higher gauge is better, and it should be coated)
- The strength of the magnets (neodymium magnets would be the best) and how many you use (we suggest 2-3, but you could use more)
- Material of the cup (cardboard, styrofoam, and plastic, for example, all produce different sounds). Plastic cups are recommended (make sure the plastic is not too hard or too wobbly)
Step 9: How Is the Sound Produced?
When you plug the headphone cable into your sound source, the sound (in the form of an electric current) goes out the wire, through the coil, and out the other end. When electric current goes through a coil of wire, the coil of wire becomes an electromagnet; when it goes around the loop clockwise there is a south magnetic pole nearest you, when it reverses there is a north magnetic pole.
If south magnetic pole of a magnet is near the coil of wire it will attract a north pole and repel a south pole of the coil electromagnet. The coil will move toward and away from the magnet (in other words, it vibrates), depending on the direction of the electric current. Because the coil is attached to the cup, the cup will also move toward and away from the magnet.
The bottom of the cup will push air back and forth, creating sounds that will travel through the air to your ear. The coil itself does not move much air, and so does not produce a lot sound. However, if the coil is attached to a large, low-mass material, it will vibrate that material, which in turn will vibrate the air, making a louder sound.
Step 10: Troubleshooting
Here are some tips that can possibly help you if you are having trouble hearing sound from your speaker:
- The coil has to be firmly wrapped around the voice coil. If the coil is not sturdy, it will be more difficult for the sound to travel.
- Make sure that there is absolutely no coating on the bare ends of the wrapped coil. You may need to burn the coil more (it’s better to burn the coating off the coil instead of using sandpaper).
- The ends of the coil should be wrapped tightly and firmly around the holes of the aux plug. Check to see if the are knots on the coil. If there are, try to fix them, or in some cases, you may actually have to replace the coil.
- Whenever you’re wrapping, make sure that the coil is straight and not knotted. The ends of the coil should be long (at least 5 inches each) and part of the ends should be tightly twisted (with at least 2 inches of separated wire after the twisted part.
- Make sure you are using a good cup. It shouldn’t be too hard or too wobbly.
Step 11: Works Cited
Tom Harris "How Speakers Work" 2 February 2001.HowStuffWorks.com. 29 February 2016