I couldn’t get the cylindrical neodymium magnet of the required size so I skipped experiment 26. Next experiment 27: Loudspeaker Destruction of Make: Electronics is a very simple and very short experiment but worthwhile nevertheless. It demonstrates how a loudspeaker works by literally cut it to pieces. Luckily I had an old 2 inch speaker lying around from a broken alarm clock. Something keeps me back in destructing brand new components.
First the black paper (the diaphragm) at the front facing side of the speaker is removed by cutting a wide circular piece out of it. A flexible yellow fabric (the spider) becomes visible. Now this yellow fabric is cut out in a wide cirkel. When the yellow fabric is pulled out of the speaker it contains a coil on a plastic cilinder (the coil former). The coil on the plastic cilinder is placed between a static inner and -outer magnet. When an (varying) electrical current is going through the coil a (varying) magnetic field is created. This varying magnetic field interacts with the magnetic field of the static magnets forcing the coil and the fabric and the black paper to move up and down creating sound waves.
There are many images and videos on the internet to illustrate how a speaker works but I discovered that none of them is as instructive as taking one apart yourself.
|The black paper (diaphragm) of a 2 inch speaker cut out with an X-Acto blade.
|The flexible yellow fabric (spider) cut out of the speaker. A left over of the diaphragm is visible on the spider.
|The spider pulled out of the speaker. On the inside of the spider a coil becomes visible. The coil fits right between the two magnets of the speaker.
|In the centre of this image the yellow fabric with the coil, a very fine copper wire wound around a plastic cilinder.