A completed solenoid.
Paper Plate Speaker
Take a strip of scrap paper and wrap it around the magnet. This piece will act as a spacer.
Wrap a second piece of paper, approximately 5-10 cm tall, around the first and tape or glue it to itself.
Remove the inner paper and you should have a small paper tube that slides freely over the magnet.
Secure one end of the copper wire to the paper tube leaving approximately 15 cm of tail.
Wrap the wire repeatedly around the tube 50-100 times. Try to keep each wrap as close as possible to the others; it doesn’t have to be neat.
Secure the wire leaving another 15 cm free.
If the wire has a coating, remove it from each end. A lighter works well for this.
Turn one of the plates upside down and attach the magnet to its center.
Construct 2 paper springs using scrap paper or another paper plate. They should be strong enough to support another paper plate and be approximately the same height as the solenoid.
Attach the two springs to the plate with the magnet.
Attach the solenoid to bottom of another plate. You can either glue the paper directly to the plate or cut flaps and tape it. The solenoid should rest overtop of the magnet, with enough space to move up and down. Trim the solenoid, or the paper springs to fit before attaching it.
Attach the top plate (with the solenoid) to the bottom plate (with the springs and magnets). The top plate should move freely.
Post-it Note Speaker
Wrap a length of wire around the four fingers of your hand, around 10-20 turns should be sufficient, leaving a length of extra wire on each end.
Put the wire loops on a Post-it Note or piece of scrap paper and cover it entirely in tape.
Remove the coating from the ends of the wire.
Audio Adapters
Attach wires to the leads on the 3.5mm stereo adapter. These wires can also be attached to alligator clips.
Amplifier
The amplifier is much more complex and difficult to build. The main component is an operational amplifier integrated circuit powered by a 9V battery. Construction will require a breadboard, as well as other common electronic components.
