So I recently got into the whole beer and wine thing, and decided if I really wanted to be professional about this, I needed a temperature controlled cellar right? Well the problem was that I didn't want to spend any money on it, so here is what I did to make my own for minimal cost. Keep in mind much of the stuff I was able to scrounge up in my room or through various other sources, but a resourceful person such as yourself should be able to do some scrounging as well.
Well time to get started. The basic idea is that in order for beer (only very certain beers) and wine (certain wines) to age nicely it should be at a good constant temperature (usually somewhere between 10C-15C). This is a bit warmer than your typical fridge and people usually have more to store than fits in their fridge.
To start off I wanted to get a really basic idea of how big this box would be, so I made a simple Google Sketchup just so I could get a feel for size. 2' by 2' by 2' seemed perfect because you can buy the foam board in 2'x4' pieces.
The first step was to build the box that all my delicious booze will go in. Styrofoam is an excellent material because it is cheap, and insulates very well. So I went to home depot and picked up the following supplies:
I had no tools in my new apartment so I had to invest in those as well. From top to bottom we see Foam Board, Caulking gun, Saw, Foam Glue, and a tape measure.
I opted for the easiest way to build this which meant mostly only having to cut boards in half (with some exceptions)
On the last image you see a meat thermometer that I will conveniently shove into the foam in order to calibrate my box and make sure it's working properly.
Now we can get to some of the cool electronics stuff. First order of business is how to keep the box cold. To accomplish this feat I used a Peltier Junction. To learn more about what this is exactly check out the Thermoelectric Effect. Luckily I was able to procure a device that already had a heat sink on one side, so all I had to do was apply thermal grease, and rubber band another head sink (stolen from an old computer) onto the other side. So now when power is applied one side of this will get hot and the other cold, guess which sides faces into the box?
Some people may not have one like mine laying around so you can just buy the actual peltier junction and fasten heatsinks and fans to both sides. Here we see it lays nicely onto the hole I made earlier in the lid of the box, we can also see how the door of the fridge will work. By glueing a smaller sheet onto the front panel it now pressure fits snuggly without letting any cold out.
Now that there's a method to cool the fridge, we now need some way to control it. I didn't have any thermocouples laying around so I ripped apart an old iPod battery and removed a part called an NTC (Negative temperature coefficient) Thermister from it. How this component works is that the resistance changes with temperature. So i can use it in a voltage divider wired to a microcontroller's ADC and calculate temperature from it. One side effect from taking from a consumer product is the size was...very small, an 0201 package to be exact. With the help of a microscope and some blank circuit boards laying around I soldered it to some open pads and used the board as a breakout for it. I added a penny to give an idea of size.
Next up is the microcontroller. My buddy had recently given me one called an Electric Imp. This controller is neat because it is wifi enabled and connects to a cloud service, so with this I can monitor and control my fridge online (I can also modify and upload new code online). Here is my code
Now I had to create a circuit to allow the Imp to control my cooler. The cooler takes several amps of power so I opted to use a relay to control it, plus relays sound cool. I then proceeded to design the circuit using advanced circuit design techniques (drew it on a sticky note). I would like to note that my circuit is not very good. It wastes a lot of power (3/4 of a watt) but I only had limited parts at my disposal and I was too lazy to solder in more transistors since I only had surface mount packages available. To help out with the circuit I grabbed some random circuit card I had laying around and soldered the components to it and then wired my own point to point connections. Very advanced techniques indeed.
Here we have it, the final product jerry-rigged together:
So this is my adventure of going from no beer/wine fridge, to having a fully functioning one at my service in under 24 hours. I know I left out many details, and if there's any questions you may have or suggestions to make this very advanced web page any better, feel free to Email Me.
|Microcontrollers||Cooling Elements||Other Hardware|