They probably won’t please the audiophiles, but [KJMagnetics] shows you that can create a pair of speakers with some magnets, some plastic cups, and a bit of magnet wire. Creating speakers out of junk isn’t a new idea, of course. However, there’s something pleasant about the build. Maybe it is the symmetry of the cups or the workbench look of the woodworking.
We couldn’t help but think that this would make a good science fair project or a classroom activity. Especially since there is a good write up on how speakers work and it would be easy to make simple changes to test different hypothesis about speakers. For example, what happens with more or less wire in the coils? What magnets work best? What does best even mean? Is it louder? Less distortion?
There’s a video (below) of the speakers in action if you want to hear what they sound like. We couldn’t help but start sketching really geeky looking headphones. However, if beer pong cups are too ordinary for you, you might prefer making a speaker out of a hard drive. Or if you want something using off the shelf speakers, we thought these would make a good rainy day project.
10 thoughts on “Speaker Science Project”
And after you’ve shown your protoge'(s) the speakers, show them they are also microphones!
Better yet, let each make their own set and then use one side as a mic and another as a speaker, connect the two sets together and you have a telephone :)
You know we used to do that as kids, but out BOM was significantly cheaper: 2 cups + string.
WSDT (Wired Short DistanceTelecom)
They sound kind of tinny uh- err plasticky B^)
Great build, the simpler the better! Its a shame how few back to basics projects show up, one of the best ways to learn is to reproduce existing experiments, whether it’s physics or OS vulnerabilities.
You can also make a simple “ribbon speaker” (think back to the 60’s) with aluminium foil and some finger-snapping magnets. https://www.youtube.com/watch?v=aagJUujcxsQ (shameless self promotion) I was using an old stereo amplifier to drive the foil at almost the lowest volume (as the impedance is pretty much 0 compared to an actual speaker) but it still squeaked out some recognizable noise.
The cup makes the narrow band resonance that you hear. Nothing else is audible.
The typical YouTube vid that is shot with a camera mic. I could barely hear it. I wish YouTube would normalize these. They de-shake vids.
This demo would have been more interesting if only one was in operation, the one closest to the camera. It’s to water down the demo it would seem.
Try other material for sure, experiment!
This is just a twist on what any kid in the 80’s probably tried with their cheap Memorex headphones (you know the ones with sizeable drivers compared to ear buds), especially if one had a busted head band; while dreaming of a righteous boombox under the Christmas tree. I seem to recall that the thick cardboard cones that yarn/twine was spooled on was quite effective as the small end was perfectly sized and only required some scotch tape to affix the driver. Cheating a bit and not as educational perhaps, but sounded about the same.
I wound my own voice coils and then taped them to the metal end of Pringles tubes. It gave an interesting sound, though never very loud (of course, I was only using a Walkman to drive it, and I was trying to be careful with it).
I did similar experiments with my memorex-style cheapo headphones!
We discovered headphones work under water, and also discovered that speakers with a mirror and laser pointer would work as a simple light show – all when we were like 12 years old, maybe a bit younger.
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