Pulse and re-form, you electromagnetic-driven speaker display

Hands up who remembers Lava Lamps from the 1970s? Fancy a 2020s version, sitting in the side of a Bluetooth speaker?

The project, by Dakd Jung, is covered on Hackaday. He calls it a “ferrofluid display cell Bluetooth speaker” (apparently the material was developed by NASA and was used both as both spacecraft fuel and sealing material).

It’s an impressive project because he makes everything himself, including the design of the speaker. We’re talking an electromagnet device, LED lighting, an Arduino, 3D printing the speaker module enclosure…

This ferrofluid display cell Bluetooth speaker moves in response to music! https://t.co/FbyHjcflyz pic.twitter.com/4WokHBuDCL

— Arduino (@arduino) April 16, 2021

How does he control the movement – the dance of the ferrofluid? It’s by controlling both the strength of the electromagnet inside and the shape of the magnetic field (via an MSGEQ7 chip, a seven band graphic equalizer). Dakd says he has programmed the device to react to the volume of each range, and it’s modifiable via a dial switch on the front.

You can get the MSGEQ7 from Sparkfun, the data sheet for which describes the separation of the sound range:

The seven band graphic equalizer IC is a CMOS chip that divides the audio spectrum into seven bands, 63Hz, 160Hz, 400Hz, 1kHz, 2.5kHz, 6.25kHz and 16kHz. The seven frequencies are peak detected and multiplexed to the output to provide a DC representation of the amplitude of each band. No external components are needed to select the filter responses. Only an off chip resistor and capacitor are needed to select the on chip clock oscillator frequency. The filter center frequencies track this frequency.

And you can read Hackaday for more details.

I particularly like the way the kick of the drum can wake up the blobs. Check out the video below: