UselessFinds
The Circuit Board That Holds a Bead in Mid-Air With Sound

sound holding a thing up

Desk Toys

The Circuit Board That Holds a Bead in Mid-Air With Sound

Two ultrasonic transducers facing each other, standing wave in between, and a polystyrene bead suspended in the null.

Buy this nonsense$9.11$4.28(sponsored link, opens in a new tab)
  • ultrasonic levitation
  • diy kit
  • physics
  • desk toy
  • science gift
  • acoustic

What Is This Thing?

Two ultrasonic transducers mounted facing each other on brass standoffs, driven by a small green board underneath. Switch it on and the sound between them forms a standing wave. Drop a fleck of polystyrene into it and the fleck stops falling — it settles into one of the nodes and hangs there, turning slightly, held up by nothing you can see or hear.

The frequency is well above hearing, so from a foot away the whole thing is silent. It arrives as a kit with the board, the transducers and the hardware.

Why You Don't Need It

It lifts objects weighing approximately nothing, a few millimetres, and only into the specific points where the sound cancels itself out. There is no application here. It will not hold your keys.

It also needs assembling, and the instructions on kits at this price are the instructions you would expect at this price.

Why You'll Buy It Anyway

Because acoustic levitation is one of those effects that sounds made up until it is on your desk doing it. The bead does not wobble or drift. It sits in the air with the stillness of something resting on a surface, except there is no surface.

Physics you have read about is not the same as physics happening eighteen inches from your coffee. This is the cheapest version of that gap closing.

The Circuit Board That Holds a Bead in Mid-Air With Sound — photograph 2

Who It's Actually For

Anyone who liked the useless box for the same reason: a machine built to demonstrate one idea and nothing else. Engineers, teachers, and people who solder.

It is a genuinely good gift for a curious teenager, and a better desk object than most things that cost ten times more.

before you click buy

This is a kit, not a finished product. Expect to assemble it, expect the documentation to be thin, and expect to spend a few minutes finding the right size of bead — too heavy and it drops straight through.

Check the listing for what powers it and whether an adapter is included, since these ship with different plug standards from the same page.

more things nobody needs