Here's a great demonstration of how a motor can be used as a speaker for less than 5 dollars. It took 5 minutes to put this whole thing together, without soldering a thing!
Step 1: Materials
Materials and tools used to make this:
(1) LM386 Chip from Amazon
(1) Breadboard from Amazon
(1) Slow motor, got mine from an old printer
(a couple) alligator clips and jumper wire
(1) Cheap earbuds
(1) Multimeter or continuity tester
(1) hobby knife
(1) wire cutter
(1) piece of fine sandpaper
(1) Something to play music
Step 2: The Schematic
Here's a schematic so that it's easier to follow along. If you don't know what a schematic is it's basically like a little map of electronics that tells how things are connected. The big rectangle thing is the chip, and the rest is pretty self explanitory.
numbering of pins on the 2nd picture
Step 3: Prepare the earbuds
Cut of the ear bud part leaving you with the audio jack part
Step 4: Strip the wires
Using a Hobby knife (careful, they are very sharp!) cut through the rubber insulation on either the left or right side (doesn't matter, we only need one)
Once you cut through the insulation, use some fine grit sandpaper to uninsulate the 2 fine wires.
Step 5: Lable the wires
Using a continuity tester (testing if 2 things are connected) place one end on the jack (see picture) and the other on one of the wires. If they are connected then then we'll call it audio negative, if not connected we'll call it audio positive, and the other wire is audio negative
Step 6: Insert the Chip
Insert the LM386 into the center of the bread board, so that no pins are connected. You might have to push the pins in a little to make them square.
Step 7: Connecting the audio
Since the audio wires are really thin, we need to use a jumper cable (any thick wire that fits in the bread board will do) and alligator clips. Insert a jumper wire into pin 2. Insert another one into pin 3. Attach an aligtor clip to each wire. atach the Pin 2 to audio + and Pin 3 to Audio -.