BrewPi: Raspberry Pi and Arduino Powered Fermentation Chamber

For the homebrew hardware nerds out there who also homebrew beer: "BrewPi is an open source fermentation controller that runs on an Arduino (for now) and a Raspberry Pi. It can control your beer temperature with 0.1 degree precision, log temperature data in nice graphs and is fully configurable from a web interface." Source code. The article has lots of photos and screenshots. The project involves rewiring the compressor's electrical connection through a PID controller, and includes both a fancy OLED display on the fridge and support for logging statistics and control over the web. If you've ever had the joy of gradually crash-cooling a lager (not too fast, not too slow), the software includes settings to effect gradual temperatures changes in the fermenting wort. Certainly fancier than a Johnson controller and a probe attached to a fermenter with a strip of insulating tape.

Do the same with a handful of transistors

[Gothmolly]

Why does it have to be a Raspberry? Why do you have to control it in C? Is it because people don't teach or know how to do it the old school way anymore? Is the effect somehow less if you DONT have a fancy OLED display?

THIS is why I cancelled my "MAKE" subscription - too much sizzle and not enough steak.

multiple control points

[exabrial]

I'd be interested in multiple control points... I've started to do pressurized fermentation once the gravity of the beer of approaches the final gravity. This carbonates the beer without a secondary fermentation, and reduces risk of introducing oxygen and contamination into the beer. If the system could electronically monitor specific gravity then seal the airlock, but blow off any excess over 10psi... would be awesome!

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Re:Do the same with a handful of transistors

[anubi]

I guess if you consider the problems you would have calibrating an analog version, along with the display interface, the digital stuff has become more practical than the old analog stuff we grew up with. Did you forget all those trimpots we always had to design in because we never knew the exact parameters of our parts?

Those old analog panel meters are now quite expensive. As well as being fragile, and never were much better than 2% accurate. The cheapest 3 1/2 digit display you get today blows them out of the water.

Personally, I enjoyed this article - as I build a lot of heat transfer controllers - and I find it very interesting what others are doing.... Not to say I would do it the same way, but others often find some way around a situation that has stymied me in the past.

I am very interested in when people start controlling compressor speed via variable-speed three-phase drives. Some washing machines already use these pancake-like motors to completely eliminate the transmission, controlling the motor speed and direction directly from a microcontroller so as to seamlessly shift the motor function between agitate and spin. I have been waiting with baited breath for a refrigeration compressor made in that manner so I can optimize the refrigeration process for whatever heat transfer I can get into the evaporator coil and out of the condenser coil. The only control point I now have is either flat all-or-nothing from the compressor and limited control of the thermal expansion valve. With finer control of heat exchanger temperatures, I can control not only air temp but also the humidity.

Articles like this constitute a design snippet to show a usable part of a larger system.

Re:Do the same with a handful of transistors

[ncc74656]

That sounds a bit fishy. A Raspberry Pi can't keep up with switching a fridge on and off to keep temperature in a range? That beggars belief. I have an Apple II bit-banging a 1-Wire temperature sensor and clock and toggling a relay on and off for the same purpose. If a 1-MHz 6502 can run a fermentation fridge, I'd think a Raspberry Pi would be more than up to the task. I'm pretty sure there's a 1-Wire USB interface available that would let the RPi use the same sensor I'm using, with less overhead.

Primitive Cider Can Still Be Amazing

[Unknown Lamer]

You can definitely make great cider that way (I've done it!). Instead of Champagne yeast, try Cote Des Blanc or an English ale yeast to get a bit of extra complexity (Champagne yeast is really neutral... an estery yeast really helps in a cider), and bump the gravity up to around 1.070-80 (maybe even 1.100 if you want to make an Applewine instead). You have to let it ferment for around 3 months (and rack it at least once! Sulfites are your friend), but the end result is pretty great with not much more effort than "try to forget that it exists for a while".

Starting off that way, I've gotten into making a lot of Cysers (think mead, but with apple cider instead of water diluting the honey)... super simple brewing process compared to beer, but the whole "it really does only start tasting great at 12-18 months after you made it" part is so painful (well, it's certainly good well before then, but once you've tasted a wine you've let properly age you realize how much you were missing... ignorance, unfortunately, proves yet again to be bliss). I'm on my third year so I have a reasonable stock built up, but boy was it hard at first...