Experiment 27: Loudspeaker Destruction

Chapter Experiment 27: Loudspeaker Destruction

Make Electronics Book Learning by Discovery
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Make Electronics Book Learning by Discovery

  • Experiment 27: Loudspeaker DestructionChapter 5242Experiment 27: Loudspeaker DestructionI’d like you to sacrifice a 2-inch loudspeaker, even though it means wasting the $5 or so that it probably costs. Actually, I don’t consider this a waste, because if you want to learn how a component works, there’s no substitute for actually seeing inside it. You might also have such a speaker already, part of a piece of cast-off personal electronics or toy you have in your basement.You will need:• Cheapest possible 2-inch loudspeaker. Quantity: 1. Figure 5-24 shows a typical example.ProcedureTurn the loudspeaker face-up (as shown in Figure 5-25) and cut around the edge of its cone with a sharp utility knife or X-Acto blade. Then cut around the circular center and remove the ring of black paper that you’ve created. The result should look like Figure 5-26: you should see the flexible neck of the loudspeaker, which is usually made from a yellow weave. If you cut around its edge, you should be able to pull up the hidden paper cylinder, which has the copper coil of the loudspeaker wound around it. In Figure 5-27, I’ve turned it over so that it is easily visible. The two ends of this copper coil normally re-ceive power through two terminals at the back of the speaker. When it sits in the groove visible between the inner magnet and the outer magnet, the coil reacts to voltage fluctuations by exerting an up-and-down force in reaction to the magnetic field. This vibrates the cone of the loudspeaker and creates sound waves.Large loudspeakers in your stereo system work exactly the same way. They just have bigger magnets and coils that can handle more power (typically, as much as 100 watts). Whenever I open up a small component like this, I’m impressed by the preci-sion and delicacy of its parts, and the way it can be mass-produced for such a low cost. I imagine how astonished the pioneers of electrical theory (such as Faraday and Henry) would be, if they could see the components that we take for granted today. Henry spent days and weeks winding coils by hand to create electromagnets that were far less efficient than this cheap little loudspeaker.Figure 5-25. Loudspeaker ready for creative destruction.Figure 5-26. The cone has been removed.Figure 5-27. The neck of the cone has been pulled out. Note the coil of copper wire, which fits precisely in the groove between two magnets in the base of the speaker.Figure 5-24. A 2-inch loudspeaker can be instructively destroyed with a utility knife or X-Acto blade.