Build your own microphone and record sound
Build a simple working microphone from a paper cup, magnet, and coil, record sounds on a phone, and compare what you hear.
Step-by-step guide to build your own microphone and record sound
Step 1
Gather all your materials and clean a small workspace so you have room to build.
Step 2
Wind the copper wire tightly around the pen 150 to 200 times leaving about 10 cm of wire free at each end.
Step 3
Slide the coil off the pen and wrap a small piece of tape around the coil so it keeps its round shape.
Step 4
Press the taped coil flat against the inside center of the paper cup bottom and tape the coil edges so it sits snugly but can still vibrate a little.
Step 5
Put the magnet on the outside center of the cup directly under the coil and tape it so the magnet lines up with the coil.
Step 6
Rub the two wire ends with sandpaper or a nail file until the metal shines to remove the insulation.
Step 7
Have an adult carefully cut open the headset cable near the plug to expose the thin internal wires.
Step 8
Have the adult point out the headset’s microphone wire so you know which wire to use.
Step 9
With adult help twist one stripped end of the coil wire to the headset microphone wire so the electricity path is connected.
Step 10
Secure that twisted connection with tape so it stays steady while you test it.
Step 11
Plug the headset into your phone and open the phone’s voice recording app so you are ready to record.
Step 12
Hold the cup microphone so the open end faces you and press record in the app while you speak loudly into the cup for a short clip, then save that file.
Step 13
Make a second recording by speaking directly into the phone’s normal microphone and save that file for comparison.
Step 14
Play both recordings back and listen carefully to compare the loudness and tone of the cup microphone versus the phone microphone.
Step 15
Share a photo and a short description of your finished microphone and your recordings on DIY.org
Final steps
You're almost there! Complete all the steps, bring your creation to life, post it, and conquer the challenge!
Help!?
What can we use if we can’t find thin copper wire or a pen for winding?
Use enamel-coated magnet wire salvaged from a small motor or the thin insulated wire from a broken electronics cable and substitute a similarly sized marker or wooden dowel for the pen while still winding 150–200 tight turns and leaving about 10 cm free at each end.
Why does my microphone record very quietly or not at all?
Check that you thoroughly sanded the two wire ends to remove the insulation (step 8), that the magnet is taped directly under and aligned with the coil (step 5), and that the twisted connection to the headset microphone wire is secure with tape (step 11) so the coil can vibrate and generate a signal.
How can we adapt this activity for younger or older children?
For younger kids have an adult do the headset cutting and wire identification (steps 6–7) while they help wind fewer turns (about 50–100) and decorate the cup, and for older children require the full 150–200 turns, let them sand the wire themselves and compare recordings from different turn counts (steps 2, 8, 13).
How can we improve or personalize the microphone and recordings?
Try swapping magnets for different strengths, vary the number of coil turns, add a light paper diaphragm over the coil to change sensitivity, and decorate the cup before sharing the photo and description on DIY.org (steps 2, 4, 5, 14).
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Facts about sound and basic electronics
🎤 Microphones turn tiny air vibrations into electrical signals that devices can record and play back.
🌀 More turns of fine copper wire in your coil usually make a stronger signal because they increase the induced voltage.
🧲 Move a magnet near a coil and you create an electric signal — that’s electromagnetic induction, the trick behind simple dynamic microphones.
🌡️ Sound travels about 343 meters per second in air at 20°C, so a clap crosses a room in a fraction of a second.
📱 Your phone records sound as digital files (like WAV or MP3) after its microphone converts air vibrations to electrical signals.
How do you build and use a paper-cup microphone to record sounds on a phone?
What materials do I need to make a paper-cup microphone and record with a phone?
What ages is this DIY microphone activity suitable for?
What safety tips and fun variations should I know before starting?
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