People love to see a trick that fools their senses. This truism was in play at the Crash Space booth this weekend as [Steve Goldstein] and [Kevin Jordan] showed off a drip fountain controlled by a bike pump.

These optical illusion drip fountains use strobing light to seemingly freeze dripping water in mid-air. We’ve seen this before several times (the work of Hackaday alum [Mathieu Stephan] comes to mind) but never with a user input quite as delightful as a bike pump. It’s connected to an air pressure sensor that is monitored by the Arduino that strobes the lights. As someone works the pump, the falling droplets appear to slow, stop, and then begin flowing against gravity.

Sadly this phenomenon is quite difficult to record in a video since the latency of our vision is integral for the trick to work. The frame rate of the video above doesn’t quite mesh with the strobing but look closely and you still see the illusion at times.

In person, the effect is so perfect that it drew a crowd all day throughout the weekend. Kids were invited to run their fingers through the dripping stream to confirm that the water was indeed real. Even if you stick your hand into the illusion it doesn’t break the effect.

The fit and finish of the fountain is commendable. Dark acrylic makes up a triangular case in the shape of the hackerspace’s logo. Water droplets are produced by an oscillating pump and fall from the apex of the triangle. A martini glass at the bottom catches the drops with some steel wool to prevent splashes. The system to recirculate the water is completely hidden from view. It’s a piece of art and really tops off the overall experience. It was a Maker Faire Bay Area hit and rightly so!