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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