One of the problems about learning too much control system theory is that you start to realize almost everything is some sort of control system. That’s the case with [Fernando Zigunov]. After observing a Rayleigh-Plateau instability in his kitchen sink, he decided to build a little display piece that shows water apparently defying gravity that he calls The Piddler.
We’ve seen things like this before, of course. A coffee pump, a check valve, and a strobe lamp with a controller is all that it takes. What makes this project interesting is the over hour-long video lecture on the theory behind why this works and how it relates to aliasing and the z-transform. You can check out the video, below.
In addition, there’s an analysis of what’s going on physically using a high-speed camera, which is interesting. Sometimes we see a video like this that glosses over the math, but not this one. Bring your calculus book and your slide rule. There’s even a differential equation or two hiding in there.
Even though The Piddler isn’t as fancy as some of these we’ve seen, it may be the best documented, at least from the theory point of view. If you don’t want to cut open your coffee maker, maybe you have a bicycle pump?