DIY Magnetic Speaker
If you have ever sat down to binge watch your favorite show on a Friday night or blasted your favorite tunes on a long road trip, the question may have crossed your mind, “How do these devices actually transmit sound?” In short, how are electrical signals converted to sound waves we can hear? While the electronic files that store this information are a crucial part of the process, the key lies in the power of electromagnetism. Without such, that favorite song you find caught in your head all day long would cease to exist.
A Look Behind The Science
To better understand how this process works, we must first look at a basic principle of magnetism: magnetic fields. When electrical currents flow through a wire, they create a magnetic field around that wire. While weak, this magnetic field is an indisputable part of translating electronic files to sound waves. In response to the changing magnetic field that affects the nearby permanent magnet, this phenomenon triggers a push and pull effect creating the necessary motion to produce sound. To simplify this process, the permanent magnet is attached to a thin membrane that collides with nearby air molecules, causing them to vibrate and produce what our brains recognize as sound.
Typically, speaker systems are built inside plastic or metal casings, leaving little room for scientific discovery without completely disassembling the unit. Building your own DIY speaker is the perfect way to teach your kids about the wonders of magnets and sound.
Gather the following materials to get started:
- 6+ feet of 30-gauge magnet wire (The wire must be insulated and not bare copper)
- At least one paper or plastic cup
- Clear tape
- Wire strippers
- Fine grit sandpaper
- Cell phone or computer with a headphone jack
- 3.5-millimeter stereo cable that you will be cutting
Remember: this project should be carefully conducted and/or supervised by a responsible adult.
- Cut the 3.5-mm audio cable in half. Strip the insulation approximately two inches off the cut end using scissors or wire strippers (available at home improvement stores)
- Inside the cable, you will notice three wires. A copper wire that serves as your “ground” wire and two additional insulation wires (typically one with a red coating and one with a white coating). These wires are the signals that your stereo system connects to
- Next, you will strip two inches of insulation from one of the audio wires (you may choose either wire inside the cable (red or white)
Start constructing your speaker system:
What to do:
- Create a tightly wrapped coil of wire with your magnet wire, using your finger as an anchor point (try to wrap the wire around your finger at least 50 times, leaving 6 inches of straight wire at each end)
- Tape the coil to the bottom of your plastic cup
- Using sandpaper, carefully strip about 2 inches off of each end of your wire
- Secure your coil wire ends to one of your pre-made stripped wires from your audio cable by tightly twisting them together, ensuring strong contact
- Wrap your wires in tape to protect against dislodgement and avoid short circuiting the connection
- Plug the other end of the 3.5-mm cable into your respective device’s headphone jack (phone, laptop, etc.)
- Choose a song and start playing it on your device
- Hold the cup up to your ear
With the other hand, hold your neodymium magnet directly below the coil almost touching the bottom of the cup
- If your wires are tightly connected, you should begin to hear the music playing (test how bringing the magnet closer and further away impacts the volume)
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