This RGB “Time Fountain” Makes Water Droplets Float in Midair

Yours eye and brain — and the connections between them — are imperfect organs. They aren’t analogous to a camera connected to a computer that is constantly recording. A more apt analogy would be a lookout on a ship relaying what they’re seeing to the captain on the bridge over a radio. That introduces the opportunity for all kinds of interesting optical illusions that rely on our inherently mushy brains. One such optical illusion can make falling droplets appear to float in midair, and Isaac879’s RGB “Time Fountain” is a perfect example of that illusion that you can build yourself.

This is actually the second version of Isaac879’s RGB Time Fountain, and the original version was built a couple of years ago. Both versions take advantage of the same optical illusion, which is essentially the same thing you see in a dark room with a strobe light. When a bright light flashes quickly, your eyes don’t have time to adjust to the dark “frames” and you only see the bright ones. With a strobe light, this makes it appear like you’re watching an old movie with every moving thing “skipping” more than it should. In the case of the Time Fountain, the light flashes are synced to be timed with the falling water droplets. That makes them look like they aren’t moving at all.

Those lights, in this case, are a strip of NeoPixels that span the space between the water nozzle and the reservoir at the bottom. A small water pump is used to pull water from that reservoir back to the nozzle at the top. The lights are controlled by an Arduino Nano. By timing the flashing of the LEDs, the stroboscopic effect can be adjusted to make the water droplets freeze in place, or even to look like they’re floating upwards. Because RGB LEDs are used, each drop can be made to look like a different color. Those components are all housed within an attractive enclosure made from laser-cut acrylic, with some 3D-printed parts inside to help mount things. If you want to build your own RGB Time Fountain, Isaac879 has published the design files and code on GitHub.