Step 1: Materials
- Scrap Wood or another material for a base
- Electromagnets, I pulled the ones you see from a broken CD drive
- Magnets, the smaller round magnets are pulled from magnetic ball and stick toys from the dollar store, and the two larger ones from a CD drive
- Plastic, such as from many electronics packaging
- Cardboard, such as from a cereal box
Step 2: Prepare the Base
You will want to make the cuts about 3mm deep and about 7-8 cm apart for each speaker. This is just enough for the plastic edges to catch hold.
Step 3: Add the Plastic Sheets
The plastic is cut longer then the grooves are apart so it bows up about 1.5 cm in the middle, where the electromagnet will sit.
To get the sheets to stay in place, use pliers to bend a lip downward on each end of the rectangle, about the depth of the groove in the base.
Step 4: Add the Electromagnets
Step 5: Add the Magnets
Next you will need to add a stack of smaller magnets under the sheet so they are held in place by the magnet above the sheet. Be sure to add the largest magnet on the bottom of the stack.
The size of the stack will depend on your speaker, the point is to get the larger magnet close to the electromagnet without touching it.
Next place the ends on the plastic sheet in the corresponding grooves in the speaker base, as shown in the picture.
Step 6: Fasten Everything in Place
Take the strips and push them into the grooves alongside the plastic. Once you have it in place, tape the end down so nothing will move. Be sure to leave extra tape to be trimmed off later.
You will want to put some tape over the edge of the speaker to reinforce it, as seen in the pictures below.
Step 7: Power It!
For my amplifier I used an H-bridge motor driver, good to 1A at 36 V.
For my music source I used an Atmega168 using PWM to generate sound.
There are many good instructions on the internet on how to build amplifiers, so I won't bore you with more details.