Tuesday 25 September 2012

Make a motor powered by sound!

another title I could have used would be make your own phone!  This is a great project to learn about the interaction between sound and electricity.

You will need:
  • 2 speakers -  I used the ones out of a pair of old computer speakers, but any speakers will do.
  •  A lead - like in a lamp lead, I found that the speaker lead itself was perfect for the job, but the longer the better to ensure it's really working!  What you are looking for is copper leads (copper is a great conductor) this is what ours looked like...
  • You will also need a pair of wire cutters, scissors or a sharp knife and Phillips head screwdrivers.  (You may also need a hammer for some speakers)
First you have to remove the speakers out of their cases so they look like this...

Next connect the wires up.  You may get away with connecting the wires quite simply - we stripped a couple of cms of the wire insulation from the ends of all the wires and then just twisted them together.  You might have to cut off whatever they have at the end, you can use wire cutters for this or probably scissors if you don't have wire cutters because copper is a soft metal.  Use electrical tape to make the connections safe.
I needed to use the solder to connect the wire to one of the speakers that had been broken.  It should be as simple as above though and ready to use!  If you don't have much wire, put a closed door between the two people using the phone you have made and make sure the rooms are quiet so you can test it.  Alternatively you can buy a length of lamp lead from some Maplin or somewhere similar.
It may need a little tweaking if you need to solder so it is a lot easier if you keep the original connectors attached to the speaker (it was frustrating having to fix mine, even though it was fun trying out my new soldering iron).  This is a great toy and lots of fun as a science project. 

How does it work?

Well, it's the relationship between sound and electricity.  Sound is vibrations, vibrations produce energy; vibrations cause a back a forth movement.  If you put your finger on your neck near your voice box (your larynx) and speak you will feel vibrations. 

In this project, the vibrations from us talking are then turned into electricity by the speakers and then the electricity turns it back into sound the other end!  Cool hey!  This is also why it works without batteries!

In fact, what we have made is another type of motor that is powered by sound.  It works in a similar way to the simple motor we made in our last motor project in that the permanent-magnet that normally consumes electricity to make motion can also be used a generator of electricity if you supply motion. The only difference is that a speaker is both a motor and generator that vibrates back and forth instead of moving round and round.

I love science!

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