Create a cone from paper.
This cone is constructed from an 11 cm diameter circle cut on
a radius line and overlapped 3 cm.
Create a face plate to hold the magnet and secure the cone in place.
This face plate is 12 cm square.
The magnet is mounted with double-sided tape with cardboard as a spacer.
Wind a coil around any convenient cylinder (3 to 5 cm). A film canister
This coil uses 1.5 meters of 28 gauge magnet wire.
Leave 15 cm of wire for each end.
Secure the finished coil by looping the ends through the coil.
Sand the enamel off of the ends of each wire.
Tape the cone to the face plate with magnet inside.
Center the coil over the top of the cone and tape in place.
Create a bracket from folded card and tape it to the face plate.
The finished speaker.
Caution: This speaker may damage a radio
or other electronic device. This speaker has a very low impedance (similar
to resistance) and could short circuit some electronic
devices damaging them.
This speaker is very inefficient. Sound levels will be low, you
have to have your ear close to the face plate to hear anything.
Here is an electronic circuit you can build to test your speaker with: -
555 Two-Tone Alarm