Welcome to this tutorial of building headphones out of Lego bricks! We are very thankful that you want to put your plastic toys into a cool use. First off, before we get started, with any D.I.Y contraption, anything can go wrong. Sometimes we even had trouble, mainly with the AUX cable, which we will go into later.
We have important explanations for how sound and headphones work, as well as our results here. If you don't want to read them and get into building, scroll down to Step 1.
Our results: In the end, we could hear sound, but not as expected. The reason why is because the magnets were too far apart and we had trouble with the AUX cable wiring. During prototyping, we heard sound as well, but they were not used with legos; the magnets were blocked only by less than half a millimeter. We used a large plastic cup, since we had no small cups during the time. Also, the AUX cable was a broken one, meaning we can wrap the coils on both ends for the speaker to work.
Sound waves travel through air pressure changes, and the sounds you hear differ depending on how frequent and how big those waves are. Speakers work like reverse microphones. They turn the electrical currents into physical vibrations that make the sound waves for your ears to pick up. The three most important parts of a speaker are the voice coil, the permanent magnet, and the diaphragm.
The voice coil component of a speaker is just an electromagnet. Electromagnets are coils of wire, and they're wrapped around some kind of magnetic metal, usually iron. When the coil moves, it pushes and pulls on the speaker diaphragm. This vibrates the air in front of the speaker, creating sound waves. The electrical audio signal can also be perceived as a wave. The frequency and amplitude of this wave, which represents the original sound wave, dictates the rate and distance that the voice coil moves. This, in turn, determines the frequency and amplitude of the sound waves produced by the diaphragm. By running an electrical current through the wire, you produce a magnetic field surrounding the coil. The difference between an electromagnet and a permanent magnet is that you can switch the orientation of the poles on an electromagnet just by reversing the current's flow.
The permanent magnet is fixed firmly into position whereas the electromagnet is mobile. The electromagnet is positioned in a constant magnetic field created by a permanent magnet. These two magnets, the electromagnet and the permanent magnet, interact with each other like any other magnets. The positive end of the electromagnet is attracted to the negative pole of the permanent magnetic field, and the negative pole of the electromagnet is repelled by the permanent magnet's negative pole. When the electromagnet's polar orientation switches, so does the direction of repulsion and attraction. This way, the alternating current constantly reverses the magnetic forces between the voice coil and the permanent magnet. This pushes the coil back and forth very fast, like a piston.
A driver produces sound waves by rapidly vibrating a flexible cone, also known as the diaphragm. The diaphragm, usually made of paper, plastic or metal, is attached on the wide end to the suspension. The suspension is a rim of flexible material that allows the diaphragm to move, and is attached to the driver's metal frame, which is called the basket. The narrow end of the diaphragm is connected to the voice coil. The coil is attached to the basket by the spider, a ring of flexible material like fabric. The spider holds the coil in position, but allows it to move freely back and forth, and not in any other directions so it doesn't transmit sound waves every direction. As the diaphragm vibrates, sound is produced.
If you have any questions, leave it in the comments. We will do our best to answer your question.
Step 1: Gather Your Supplies!
What you will need is the following:
28 AWG (American Wire Gauge) Copper Wire: This is to create the coils and connect every working part.
4 Neodymium Magnets (1 cm diameter recommended): This will create vibrations through small movements, created by the electromagnetic coils.
Electrical Tape, Fabric, aluminum foil, or something to cover up the inner workings: This is so the headphones look firmly assembled and to prevent any loose parts from falling off.
Lego Bricks (Color doesn’t matter. What most is the design fits your head and that it doesn't break)
Krazy Glue (optional)
AUX Cable (commonly known as well as a 3.5 mm headphone jack): This is what we will be using to make the connection between the audio device and headphones.
An audio source (MP3 player, smartphone, etc.)
A glue stick or something circular (to coil the wire) Sandpaper (160-180 grit size recommended)
Have all the items? Great! Let's get started!
Step 2: Coiling
Wrap the copper wire around the glue stick. Keep wrapping the wire and don’t overlap them. You can stop whenever you feel that there is enough. We chose to use 20-30 coils because the higher amount of coils the better (since it increases quality and clarity of the sound). Make sure to leave at least one inch unwrapped on both ends. The reason why we use the extra wire is because later, when you plug in the headphones into your device, the device sends electricity through the copper wires, causing them to be highly conductive (when sanded, of course) and vibrate at different levels, depending on what type of sound you’re playing. The coils act as circular magnetic wall, to cause the magnet to vibrate evenly.
Step 3: Sanding and Removing Coils
Tape the coils in place so that they don’t unwind. Sand off the unwrapped ends of the wires to remove any extra insulation. The reason why we need to sand the coils is because the insulation prevents any electricity from flowing through the wire. Remove the coils from the glue stick, without destroying the coils.
Step 4: Design
Now we are going to create the headphone design, we chose to use Legos for creativity. We recommend LEGO Technic, since they are adjustable and highly functional. Assemble the headphones using the LEGO bricks shown in the picture. Or don't! Be creative! (You can create your own design, but follow the instructions closely in order to get your headphones to work). The Krazy Glue is optional, if you choose to make these headphones permanently usable.
Step 5: Headband Wire
Add a 10-15 inch copper wire through the headband of your headphones. Make sure there is enough copper wire on both ends to connect to the coils. Again, the ends need to be sanded.
Step 6: Magnet Installation
Place two of your magnets to the exterior and interior of each headphone cup. Place the coils carefully around the magnet and tape them. Then remove the interior magnets and carefully place them close or on the other magnet. The magnets help the electromagnetic coils move around because you need two different magnets in order for them to “stick”.
Step 7: AUX Connection
Take the AUX cable and 8 inches of copper wire (10 if you don’t have a pre-installed wire ). If the cable doesn’t have any pre-installed wire, insert the copper wire (after you sand the ends) and connect the wire with the headphones. If you have a pre-installed wire, wrap part of the wire on the AUX cable wire and connect the other end to your headset.
Step 8: AUX to Headphones
Wrap the ends of the headset copper wire to one end of the circular coils. Then, take two lengths of wire (about 10 inches) and sand them fully. Attach the ends of both wires to the other ends of the circular coils.
Step 9: Beautification ( Also Known As Securing the Build )
Cover the wires using fabric or aluminum and tape them to the cups. Make sure the build is secure.
Step 10: Try Them Out!
Plug the AUX cable into the audio device and test them out! Make sure the volume is at a maximum if you can’t hear anything.
Step 11: Troubleshooting
If the headphones don’t work, there are 3 possible reasons. You either didn’t connect the wires securely through any section. (The AUX cable is the most common reason why the headphones don’t work. Make sure both ends don’t touch each other, but touch the bottom prongs of the AUX cable), the magnets are too far apart (there should be little if any obstruction between the magnets), or you didn’t turn your device’s loudness to its maximum. (Remember, these are experimental. They aren’t high tech, so you need to have the loudness as high as possible).