A bunch of folks have asked (well, two) about a build thread for the fermentation chamber I posted on in the ebay aquarium temp controller build thread
. Even though I REALLY didn't do anything that other people already haven't done, I'm happy to oblige in the hope that it helps folks out.
Credit where credit's due.
The original build that completely inspired this was thomcat333's thread.
This is a reproduction of his work, with a few minor modifications. Really really really, all credit goes to him. Mad brownie points to shushkiary for coming up with the idea of using the relay to control the fan.
I didn't take any pictures of the build in progress (too busy working on it!) unfortunately, but thomcat's build thread details it nicely - I was able to follow it without an issue (and I'm dumb as a rock). I just sized it bigger, because I want to be able to roll a sankey in there and ferment in that, plus I live in Northern California, so I wasn't too worried about having to control the box in extreme temperatures. If you live in Arizona or Alaska, where extreme ambient temperatures are more of an issue, your mileage might vary with a box this size. The insulation I used was 3/4" R5 R-Max stuff from Home Depot
, which fit perfectly in the frame, and was easy to cut and work with.
A word of warning
- like every project, this started out "cheap". I scored the mini fridge for nothing, literally a day after seeing thomcat's build thread, and thought SCORE! But honestly, by the time I bought the lumber for the frame, plywood for the exterior, laminated board for the inside, hinges and hardware for the door, plus a tube of liquid nails, tube of silicone, and screws, I could probably have scored an upright freezer on Craigslist - and not have the FUN three hours of delicate work (and not cut the ****e out of my fingers and hands) from gutting that fridge, plus the 3-4 evenings of putting the cabinet together after work. But there's something inherently groovy about having built this thing myself from scratch, and it made it a LOT easier punching holes for the heating pad and fan, knowing that there were no coils to rupture. But here's a rough breakdown of the cost:
Lumber: (Four 1.5x1.5 furring strips, two 2x4) $17 (Local lumber store)
One sheet 8x4 1/4" plywood: $16 (Local lumber store)
One sheet 2x4 1/4" plywood: $9 (Local lumber store)
One sheet 8x4 3/4" RMax insulation: $14 (Home Depot)
Hinges: $4 (Ace)
Draw latches: $6 (Ace)
Two sheets 8x4 1/4" laminated MDF panelling: $22 (Local lumber store)
One tube liquid nails, one tube silicone caulk: $12 (Lowes)
Ye Olde ebay aquarium temperature controller: $29.00 shipped
6x4x2 project box from Radioshack
(a little tight, a bigger one might be better): $4.99
Rocker switch from Radioshack
Two pilot lights
(one blue, one red - neon 115v AC) from Electronic Plus: $12
Two three-port terminal blocks from Electronic Plus: $1 each or so.
Relay from Radio Shack
12v Computer Muffin Fan: $5
Power Supply (old ac adapter): Free
Mounting Screws (4x 3.5" #10 screws, 12 nuts): $4
Cooling is provided by the guts of an old mini fridge I scored for free.
The heating is provided by a $29.90 Brewer's Edge space heater pad from Williams Brewing
which sticks to the back of the cabinet.
Grand total: $199.39 (phew!)
So, once the cabinet's built, there are two areas of wiring that went on: the control box itself, and then another box at the back of the cabinet. The rear wire box is just a standard two-gang plastic junction box
that I had lying around that houses a ton of wire nut connections, and the relay which provides power to a clipped female end of extension cord for the 12v fan.
So here's the wiring diagram. Basically, power comes into the junction box at the back via an extension cord that was clipped. (I cut it 6" from the end of the outlet, which I saved and used for the fan.) The control box, mounted on the top, has four wires heading down to the junction box - one black for power, one white for neutral, and then two more (I used red and blue tags on the wire, so I could tell them apart) which will provide power from the switch to the heater and cooler. While the control box is nice and neat, the rear junction uses copious amounts of solder and wire nuts, but they're tucked out of the way and hidden at the back, so I'm not worried about them.
Shushkiary explains the relay a lot better than I could,
but basically tag one is always on unless there's power to the coil (7 and 8). Which means when the box fires the fridge guts, it also provides power to tag 2 because that's where the switch stays naturally. So when the fridge works, the fan works. When the controller fires the heater, it powers the coil which causes tag 2 to flip. Now it's in contact with tag 3, so there's power to the fan still.
That should make sense. Hopefully, at least. I understand if it doesn't, since it took a few reads and rereads of many posts and threads in order for me to figure it out - at which point a light went on and I thought "Oh yeah!" But if you have any other questions, let me know. (Hopefully someone who knows what they're doing can answer them, I probably can't.)