The more observant among you may notice that I've not written about my mother's illness late last year. I didn't want to proceed writing this blog without addressing it, and I've written an entry, but I'm not ready to publish it, and I might never be. I am happy to report that my mother is recovering well from her bilateral lung transplant last year.
I've recently gotten back into DIY and electronics and robotics and things of this nature, which is going to be an ongoing process but it's a return to a hobby much beloved in my childhood. Moreover, now, with more experience under my belt, and the advent of affordable DIY microcontrollers like the Arduino, I'm having a lot more fun with it, too.
One of the notions I had that was the inspiration for this return to DIY electronics was the idea of a microcontroller-maintained sensor network inside a beer fermenter that would accurately chart the progress of the beer over time, alert me of any problems occurring during fermentation (such as excessive barometric pressure, rapid changes in temperature, possible stuck fermentation), but most of all just be something cool and beer-related I can geek out over for a couple of months in my all-too-scarce free time.
The first challenge I had to overcome while designing the brewbot (it'll have a proper name once it's built; I don't want to name it yet) was how to digitally and accurately measure the density of a liquid. I asked many engineer and physicist friends of mine how this could be accomplished, and they came up with some pretty cool ideas, but in the end the direction I decided to go with was the same way that industrial proximity and density detectors work: by measuring the relative capacitance of the subject material (in industry, this is usually steam or something, I think; I wasn't exactly clear on that).
As it happens, capacitance sensors are also familiar to most people as the way that touchscreens now work, as well as buttons and switches on many electronics (my TV and my computer monitor both have touch-operated switches that work by surface capacitance). So, these kinds of sensors are both easy to come by and also inexpensive relative to their industrial counterparts. I purchased a breakout board for one such sensor from Sparkfun and have assembled it. Going to test it out today.
I've also hooked up a small 2x16 letter LCD display that will be a convenient way to display the data the sensors collect until I can work out something better. Ideally I'd like the data to be available over the internet, but also I think I'd like the Arduino to be able to store them to an SD card or something for me to read later and construct time graphs of for each beer I make. That information would be not necessarily vital to my brewing process but certainly fascinating. In particular knowing how different strains of yeast react would be useful information for planning my future brews.
I will be assembling a prototype for the capacitance sensor setup today, which I will hopefully be able to use to get some data points of capacitance measured vs specific gravity or density measured. Ideally I'll have something that can output specific gravity or Balling scale, and do it a few times every hour. More on this later, space cadets; that's why I put "part I" in the title.