Printed circuit boards used to be green or tan, and invariably hidden. Now, they can be artful, structural, and like electronic convention badges, they are the entire project. In this vein, we find Open LEV, a horseshoe-shaped desktop bauble bristling with analog circuitry supporting an acoustic levitator. [John Loefler] is a mechanical engineer manager at a college 3D printing lab in Florida, so of course, he needs to have the nerdiest stuff on his workspace. Instead of resorting to a microcontroller, he filled out a parts list with analog components. We have to assume that the rest of his time went into making his PCB show-room ready. Parts of the silkscreen layer are functional too. If you look closely at where the ultrasonic transducers (silver cylinders) connect, there are depth gauges to aid positioning. Now that’s clever.
Acoustic levitation takes advantage of the nodes in a standing sound wave. Nodes are points surrounded by higher pressure regions. In other words, if something rests inside a node, any direction it wanders, it will encounter pressure pushing it back. There are also antinodes where nothing wants to hang out. If something disrupts the wave, even from above, the levitating thing will fall.