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I designed this speaker as an easy, inexpensive way for artists to embed sound in their work. I also created it as part of a larger (somewhat quixotic) quest to knit working electronics. The speaker can be made with or without knitting. Instructions for both designs are included.

The Basic Design

Rows of parallel magnet wire, glued between two pieces of paper, carry the audio signal. The wires are positioned over the mid-section of the magnet.

This creates an effective speaker because hard drive magnets are dipolar.
The broad face of the magnet has both a north and south pole.

When the red line on the paper rests on the red line on the magnet, it produces a clearly audible speaker.

Video:

Hard Drive Magnet Speaker Demo

Knitted Speaker Demo

Step 1: Build the Speaker

Materials:

  • masking tape
  • 32-36 AWG magnet wire
  • tracing paper
  • cooking parchment paper
  • metal leaf spray adhesive
  • hard drive magnet
  • two 8 ohm 20 Watt resistors
  • Class D or T amplifier

Find a jig to wrap your wire around.

Tape one end of the wire down on the jig. Wrap the wire tightly around the jig to create at least 10 parallel rows of wire. Avoid twisting. Once you're done wrapping, tape the other end of the wire down as well.

In the photos, I'm wrapping the wire on a warping board, but a large square of cardboard will work just as well. Place a piece of double sided tape along opposite edges of the cardboard to hold the wire in place as you go.

The total width of the wires should be narrower than the length of your hard drive magnet.

<p>I am definately going to test this out. Cool!</p>
<p>Awesome! I'd love to see how they turn out. </p>
<p>This is awesome! Thanks for sharing! I love homemade speakers and yours turned out looking simply amazing!</p>
this is do rad! thanks for sharing your project and providing such stellar documentation!
<p>Thank you! People have asked me for more info on the design so I wanted to create an accessible explanation. </p>
<p>This is awesome! Thanks for sharing! I love homemade speakers and yours turned out looking simply amazing! </p>
<p>Thanks! I'm hoping this will be useful to other people designing their own-- so many interesting approaches out there!</p>
Electric current is the movement of electrons (which have a negative charge). This would mean that the current moves from negative to positive. Perhaps the orientations of the forces you proposed are not affected but just be aware of this.
<p>Fleming's Left Hand Rule uses conventional current flow (from positive to negative) instead of electron current flow. It's kind of a funny story how the difference between the two started, <a href="http://www.allaboutcircuits.com/vol_1/chpt_1/7.html" rel="nofollow">going back to Ben Franklin</a>. Either notation works as long as it's consistent. </p>

About This Instructable

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Bio: I'm an artist and associate professor at Columbia College Chicago, where I teach audio and electronic art. I make sound art, kinetic sculpture, and ... More »
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