Bubble Displays Are Increasing In Resolution

PipeDreams 3 bubble display

[Bruce] has created a pretty cool bubble display that is capable of showing recognizable photographs of people. This entire art installation is no slouch at 3-stories tall! This one resides at the Ontario Science Centre in Toronto, Canada. If you are unfamiliar with bubble displays, they consist of several clear vertical tubes filled with a liquid. A pneumatic solenoid valve mounted at the bottom of each tube allows a controlled amount of air to enter the tube at a very specific time. Since the air weighs less than the liquid, the air bubble travels up the tube of liquid. Interesting patterns can be made if these bubbles are timed correctly. This setup uses a Linux-based computer with custom control software to manipulate the valves.

[Bruce] didn’t start off making super-complex bubble displays. This is actually his 3rd go-around and with 96 individual tubes and capable of displaying raster images, it is the most complicated so far. His first creation consisted of 16 tubes, each larger in diameter than the most recent creation. With the larger diameter and less number of tubes came less resolution and the ability to only display simple shapes. Version 2 had twice as many tubes, 32 this time. In addition to doubling the tube quantity [Bruce] also colored the fluid in the tubes, not all the same color but all the colors of the rainbow, from red to violet. Still, this version could not show raster images. It appears to us that the third time’s the charm! Video after the break….

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An improved bubble display with RGB LEDs

Making a bubble display is quite an undertaking, but [Jay] takes advantage of iterative design to construct this impressive (and at 60 tubes, massive) bubble display. The display functions by dispensing bubbles to serve as illuminated pixels in each tube as they rise through the fluid. His build log steps through the display’s construction with a keen attention to detail and above all, patience.

Rather than diving right in and slapping some tubes together, [Jay] took the time to research other bubble display projects, including one we featured a few years back that grew out of yet another HackaDay article. His prototypes started off small to test potential features: whether to use water or glycerin, timing for the air pumps and bubble size, and several others. [Jay] even filled the log with videos of every test, so you can watch the problems and solutions unfold at each step.

The finished display boasts sixty 30″ tall tubes, making it 64″ wide. [Jay] also installed RGB LEDs at every edge where the tubes meet to better distribute the light. You can watch one of the many videos of the display at work below.

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Logging bubble frequency and pressure in your fermenter

In an attempt to add technology to his brewing process [hpux735] build a sensor rig that monitors bubbles and pressure during fermentation. What does this have to do with brewing great beer? We’re not sure and neither is [hpux735], but he’s got some preliminary readings to spark your imagination.

The bubble sensor itself was inspired by a SparkFun Tutorial where fermenting wine was monitored with a data logger. It uses an optical gate to detect the passage of air. But the goal here was to combine bubble frequency with internal pressure measurements to calculate how much CO2 is being vented. Perhaps it would be possible to get an idea of how close the batch is to completion based on those calculations. A hole was drilled into the fermenter side of an airlock to take these pressure readings.

This actually works quite well during secondary fermentation when the bubble frequency is quite slow. The hardware is able to discern a pressure difference before and after a bubble has passed the lock. Unfortunately the system breaks down during the vigorous bubbling that takes place soon after pitching yeast. See a few bubble-counting clips in the video after the break.

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Bubble Display

As hackers we have come up with some pretty wild and unique ways to display data, but that never stops us from creating even wilder ways such as this Bubble Display. Inspired by a Hackaday article called Liquid Display the bubble display started out as a one column lexan tank so the team could check out different liquids, and build methods, which gave them the opportunity to test out their wet/dry vacuum in the basement as well.

After the leaks were solved in the prototype, different fluids were tried out to see what would work best,  glycerine (though the most expensive out of the 3 items tested) gave the best performance in how the bubbles rose to the top, and the uniformity of each individual bubble.

The final tank design features (24?) channels to keep bubbles from interacting with each other and are fitted with some Parker A005-C23-2P pneumatic valves hooked up to a standard air compressor. Electrically it’s pretty standard, with the solinoid driver stuff all run by a PIC18F4455 clocked at 48MHz.

Software wise the device has 3 modes, one mode allows users to enter text or simple bitmaps from a computer using a homebrew GUI written in Visual Basic, there is also a demo loop for when you still want to show it off, but there is not someone there to constantly bang data into it, and finally a live keyboard mode which acts as a bubble music visualizer when there is a keyboard connected via MIDI. Check all 3 out in a short video after the break.

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