I'll take it that you too are desperate for a cold drink during a hot drink while sitting behind your desk. Sadly, placing a fridge next to your desk is a bit impractical. Luckily, there's a diy solution to that: the CoolCup. Above you can find a list of what you will need to make this cool device work:
- A normal ruler and a triangle ruler
- Thermal paste
- A drill (or any other electric drilling tool, like a Dremel)
- A soldering iron and soldering tin
- A thin aluminum sheet
- A normal or electric saw (one for metal cutting is advised)
- A heatsink (don't take one that's too small, you will come to regret it)
- A peltier element
- A 5A 12V DC power source
- 2 12V fans to keep the heatsink from overheating
- A raspberry Pi
- Wires for electric wiring
- A 5V relay (that can survive the 5A, here I use one that can withstand 8A and 250V DC)
- Superglue (don't go cheap on this)
- 2 LM35 temperature sensors
- A PNP transistor
- A 1000ohm resistor and a 220 ohm one
- A diode
- Multiplex wood
Step 1: Soldering
So let's start with what is important: getting the electronic circuit to work. If you make a mistake here, your project might make your drink go up in flames instead of cooling it off, so follow this fritzing scheme carefully.
Note: make sure you don't put your relay in the actual board, the large current will cause overheating and might damage your circuit.
EDIT: I have tested my circuit out again, and there seems to be a problem with my transistor. If this is the case, I suggest connecting the diode pin with a ground pin. This will unable you to toggle your cooling on or off with code, but it should keep the pertier element running.
Step 2: The Casing
The casing is rather simple to make, if you have the proper material.
First off, you need to cut out 2 plexiglass squares of 18x18cm. Then you cut out the appropriate walls for it (keep in mind that you must compensate for the thickness of the plexiglass for this, so 2 of the walls should be 2x the thickness of your plexiglass extra in cm (for example, I use 4mm thick plexiglass: 2 walls will be 18.8cm wide while the other 2 are 18cm wide).
Next up: the aluminum. For this, you want to cut out a sheet of aluminum. You want it to be roughly 20.4 cm long, and about 5cm in width. You bend it into a circular shape until you can fit a can in it.
Next, you cut out a circle of around 7cm in diameter in aluminum. This will also have 4 'arms' extending from it. This is so you can glue the previously mentioned aluminum piece to it. I suggest the usage of aluminum, since it's light and it conducts heat and cold really well. But feel free to use any other material of your choice with the same qualities.
Don't forget to drill holes at the appropriate spots for your raspberry, your power supply, your fans, and your pertier element.
UPDATE: I have redone the casing for the project in wood, since in the end the plexiglass didn't fit my needs when it came to thickness.
Any wood will do for this. This time though the squares are 19x19 cm. And at the top cover, I have cut out a hole to let the aluminum cupholder through. Said cover also has 4 squares of 3.5x3.5cm. This should allow you to easily remove the cover and to keep it in place when it's closed.
Step 3: The Heatsink
The pertier element works really simple: you create a current inside the element, due to which heat will be extracted from one side of it to the other. Problem here is: one of the 2 sides will be extremely hot. We will counter this by placing a heatsink under the pertier element, to which we will also attach 2 fans to stop the heatsink from overheating.
NOTE: Make sure the fans are blowing the heat outwards, and not inwards.
Step 4: Finishing
Once you have applied thermal paste to the pertier element and the aluminum cup, You put them together firmly, and assemble the parts inside. Once that is done, you close off the casing and you are fnished! You now have a working cooler for on your desk!