Turn Old Hard Drives Into Planar Speaker Drivers

We love technology here at Hackster, but we also recognize the reality that e-waste is a serious problem when it comes to sustainability and environmental protection. That's why we're big fans of projects that recycle or upcycle electronics that have become obsolete and that would otherwise end up in landfills. By giving old electronics new purpose, you both avoid purchasing a new product and you keep that device from going in the garbage. If that sounds good to you and you have access to old hard drives, then JGJMatt has a tutorial that explains how to turn them into planar speaker drivers.

All speaker drivers turn electrical signals into mechanical energy: generally vibrations in a speaker cone. Most speakers do that by passing the amplified audio signal through an electromagnet, which attracts a permanent magnet attached to a speaker cone. But there are other types, including planar speakers. A planar speaker has permanent magnets on either side of a membrane with an embedded coil. As the amplified audio signal runs through that coil, the membrane vibrates between the two magnetic planes. That vibration pushes air and makes sound, just like any other speaker.

That requires powerful permanent magnets and hard disk drives just happen to contain some. Hard drives also have other useful components that you can use in different projects. As JGJMatt explains, you will need to cut the magnets in half with a diamond cutting wheel on a Dremel. Hard drive magnets have their poles at opposite ends, so this is necessary to create a more uniform magnetic plane.

Those chopped magnets will fit into 3D-printable holders that JGJMatt designed. The driver then needs a membrane with coil in-between the two magnetic planes. JGJMatt provides a few different fabrication techniques that you can choose from depending on the tools you have. The simplest is a thin 3D-printed membrane with a spool-like structure where you can wrap copper wire to create the coil. You can also make a membrane using UV-etching techniques like what you'd use for a custom PCB. Or, if you have a resin 3D printer, you can take advantage of a similar method to cure resin that acts as the mask.

The method you choose will absolutely affect sound quality, but JGJMatt uploaded an audio clip demonstrating the 3D-printed membrane and it sounds pretty decent. It won't satisfy the audiophiles, but it is enough for low-stakes applications and would be a fun weekend project.