[Photo from Connors934 on Flickr]
This speaker project was part of the electricity and electronics class at DHS. The parts were mostly junk except for the magnet wire. We made headphones from bottle caps, speakers from shipping tubes, lights, pvc, coffee cups and italian ice cups. Packing tape or regular adhesive tape works well for the membrane attach the coil of magnet wire directly to the membrane and mount the magnet a bit away from it.
When the coil is charged by the audio circuit, the coil either attracts or repels the magnet. We used an old stereo and drive the home made speakers off the speaker outputs, which was moderately successful, because some kids found a little too much joy from destroying the speaker by turning the volume way up until the wire heated through the plastic cone material. An old radio, cd player or mp3 player might be a better device to drive them from because of the decreased output from the headphone jacks.
The magnets we started with were mostly ceramic disks that I bought for the mendocino motor project. They turn out to be not very powerful. The rare earth magnets in hard drives, or the ones found in busted speakers work much better.
[Photo from Connors934 on Flickr]
These speakers did work, but they were anything but high fidelity. The real value in the project is seeing and showing kids that it can be done. Kids should see that they can make their own stuff like speakers rather than believe that everything comes from factories. A number of the students in the class went on to study engineering in college, others are just more curious as they move through the world.
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