A speaker project isn’t usually very different, but we couldn’t help but notice [Electronoob’s] latest speaker not for its audio performance but because it features dancing ferrofluid and is an unusual work of art. The housing is 3D printed and includes some translucent portions for LEDs.You can see and hear the speaker at work in the video below.
Apparently, not all ferrofluid is created equal. You can get just the fluid, but then you have to work up some sort of carrier fluid. You can also get the material already in a glass with a carrier fluid, which is a better option. Apparently, you can also get cheap material that is little more than iron filings suspended in a liquid. That’s not really ferrofluid.
The rest of the build is what you’d expect: some speakers and a simple amplifier. The magnetic portion uses a 24V electromagnet. A few MOSFETs and some discrete components make a simple driver for the magnet. We wondered if it would be possible to use multiple magnets that would drive at different frequencies to make a kind of spectrum display using the ferrofluid.
The holes for the brass threaded inserts were accidentally too big, so he epoxyed them in. We don’t want to reveal if we’ve ever done that, but we know it works fine in a pinch.