Monthly Archives: October 2016

Homebrew Fermentation Temperature Control

I was planning to build out a BrewPi but decided to go with a DIY BlackBox Brew. The BlackBox is more than capable of handling what I need and it only cost ~$42 CAD all in.

The main parts for the project were:

  • Wine Fridge – $50 Used (Excellent price!)
    • I slightly cut down one of the wire shelves so it fit just above the compressor hump.
      • Liquid Electrician’s Tape sealed up the cut ends nicely.
    • A short length of ABS pipe was added to help support things.
  • VIVOSUN Waterproof Seedling Warming Heat Mat – $21.95
    • Using an aquarium heater in a mason jar while I wait on the mat to arrive
  • STC-1000 A-400P version – $25.36
    • Note you _must_ use this seller to ensure the A-400P version
  • HomeDepot Junction Box – $13.16
  • HomeDepot Grey Outlet – $3.80

I also needed an extension cord which I cut down to run power to the BlackBox, an outlet face-plate (as a template and for its included screw) and an Arduino to do the programming.

I started by opening the STC-1000 and soldering in a programming header. I attached cables so I can route out the header allowing for easy updates in future.

controller-programming-headercontroller-parts

 

I had to cut off the receptacle’s tabs so it would fit the enclosure. I used a horizontal metal cutting bandsaw but a hacksaw would be fine too. You also want to break off the tab from the ‘hot’ side of the outlet (narrow slot side) to separate the outlet into heating/cooling sides.

controller-plug-modified

 

I located the center of the box and drilled an undersized hole for the screw. Using that, I screwed the receptacle cover to the box and traced the shape with a sharpie. Following that template I simply plunge milled a wallop of 1/8 holes using my mill. The resulting cutout was a surprisingly accurate snap fit. For the STC-1000 I measured and traced a template then similarly plug milled a bunch of holes; followed up with a pass on the mill to smooth the lines.

controller-plug-installed controller-dryfit

 

Ultimately, the fit was very very tight! The STC-1000 has a little wiring cover which I had to leave off. Further, it had a little nub to receive the screw for this cover, I had to cut that off to make it all fit.

controller-dryfit2

 

You end up needing two neutral wires (one to power the STC-1000, one for the outlet) and three hot wires (one for the STC-1000, one for the Heating relay, one for the Cooling relay) and a single ground for the outlet. Merretting all those connections would consume too much space so I soldered and used heat shrink instead. I tinned the ends that will go into the STC-1000 as I find that prevents stray wires and tends to grab better. I drilled a tight fitting hole for the power cord and split/knotted the insulation to act as a stress relief. A tight fitting hole for the temp sensor was added on the other side.

controller-wiring-prepped controller-wired

Once it was all together, I connected it to the configured Arduino and programmed it. Note the STC-1000 will emit a disconcerting buzzing sound during programming, apparently that’s normal/expected.

controller-programming

 

For the header I installed the connections were:

  • ICSPCLK – Pin 9 – Blue
  • ICSPDAT – Pin 8 – Purple
  • GND – GND – Grey
  • VDD – 5V – White
  • nMCLR – Pin 3 – Black

 

The ultimate plan is to strap the temperature sensor to the side of the carboy with a sponge/insulation over it. This won’t be as accurate as a thermowell but it’s simple, cheap and ought to be sufficient.