Water-to-Wine Cooler

For this project you’ll need to do some soldering, drilling, cutting, and simple microcontroller programming. Total project cost is about $300.

You’ll also need to grab our Water to Wine (W2W) code for the AVR microcontroller: https://github.com/partyrobotics/water-to-wine or git@github.com:partyrobotics/water-to-wine.git

Here’s the block diagram that shows how all the components of the system interact.

And here’s the layout diagram showing where all the secret components will go inside the cooler.

First, remove the top cap on the water cooler with a half turn.

Remove all visible screws in the cooler, and strip it of all excess insulation, tubing and wiring. Don’t throw anything out yet; you’ll need some of it later.

CAUTION: The metal chassis can be sharp, so take care not to cut yourself.

Work with a friend, as extra hands will come in handy. We took our time, about 3 hours picking apart the guts, and it was fun seeing how the water cooler works and how its mechanisms inside are packaged.

TIP: To keep track of where the small screws come from, it helps to label pieces of duct tape and add the screws to the sticky side.

Refrigerant compressors made before 1995 may contain chlorofluorocarbons (CFCs), which harm the ozone, so you need to take them to a refrigerator repair shop where they can safely evacuate those gases.

Our compressor was new and contained R134A refrigerant, which is not illegal to vent, but still contains greenhouse gases. I used heavy bolt cutters to cut and quickly crimp the copper tubing to minimize leakage.

WARNING: This is a job best done outdoors, and you should avoid inhalation and skin contact.

If in doubt about your compressor, call a local refrigerator repair shop or learn more at epa.gov.

Remove the water reservoir (surrounded with foam insulation) and set it aside; you’ll reuse it.

Finally, remove the LED assembly behind the front panel. You’ll substitute your own LEDs. You should be left with an empty chassis.

Add a 4″ extension to the mini lever switch and superglue it in place. We used a scrap of aluminum sheet cut with tinsnips. If your switch has a roller on the lever, that can be a useful attachment point.

The hot and cold dispense buttons activate the valves inside by pushing plastic sliders. Position the switch body on the plastic bracket on the hot water side, so that the cold water slider will click down its lever. Make marks for its mounting holes.

To secure the switch, drill and tap #2-56 screw holes. We used metal screws, but plastic screws would probably be better because the plastic is pretty soft.

Screw the switch into place and make sure you get reliable clicks when the button is pressed from the outside.

Make the float extensions by cutting 1/2″ acetal tubing: a 4” length for the water sensor, a 3/4″ length for the “wine is full” sensor, and a 4-1/2″ length with a 2″ right-angle extension for the “wine is empty” sensor. For this extension, drill the main tube, or miter both tubes, then glue the extension on with silicone.

Thread the bottom of each tube with an M8 tap, and screw each sensors into its tube, feeding the wires through.

Use a step drill to make a 1-1/8″ hole in the cooler’s back cover for a bulkhead fitting, and another small hole for the “wine is full” LED to shine through.

TIP: Step drills are great for drilling thin material. They make much cleaner holes than spade bits or hole saws.

The wine reservoir is made of polypropylene, which has a great combination of chemical resistance, availability, cost, and workability. It’s usually milky in color and marked with the number 5.

In the bottom of the reservoir, drill a 1-1/8″ outlet hole and mount another bulkhead fitting. Keep placement in mind because you’ll need to make a matching cutout in the metal shelf it sits on.

Drill a hole in the side of the reservoir to fit the “empty” right-angle float sensor. It’s best to make this hole high up on the container to minimize potential leaks.

Drill 2 holes in the lid: one for the “full” float sensor, the other for the wine fill tube. Both holes should roughly match up with holes in the plastic shelf above.

Mount the wine float sensors and use silicone glue to seal any gaps.

Make 4 holes in the water cooler’s lower, metal shelf: 2 to match the holes in the pump container lid (make sure there’s space for the pump outlet barb to poke through), one for the pump connector to pass through, and one for the flex riser to pass through.

Use a Dremel or other high-speed rotary tool to make a cutout in the metal shelf for the wine reservoir’s bulkhead fitting.

The wine pump sits in a plastic snap-lid container of its own, surrounded with bubble wrap to quiet it down. This is optional since the pump comes with its own mounting bracket, but silencing the pump improved the illusion.

Make 2 holes in the pump container, one for the wine inlet and one for the pump wires.

Make 3 holes in the pump container lid: one for the pump outlet, and 2 for machine screws that will suspend the container under the cooler’s metal shelf.

For the W2W status indicators, use the cooler’s original front indicator panel, swapping in your own green, blue, and red LEDs and their matching resistors.

On the LED circuit board, desolder the LEDs and resistors, and clip off the diodes. Solder your new green, blue and red LEDs in place, adding 560Ω, 1kΩ, and 390Ω resistors, respectively. Crimp a 4-pin connector to the wire bundle and install the board back in place with 2 screws.

Solder the end of a standard power cable to the power cord wires inside the water cooler.

Connect the cooler’s original power switch to the output side of your power adapter, using spade connectors.

Insulate all individual wire connections, and each bundle, with electrical tape or heat-shrink tubing.

Polarity doesn’t matter for the mini lever switch, gravity valve, and float switches, so you can solder a same-color wire pair to each of these components. Then connect matching wire pairs to the control board’s screw terminals, as seen here in yellow, white, and green.

The pump wires are polarized, so connect a different-color wire pair here — in our case brown for power, black for ground.

Crimp Molex connectors onto all wire pairs, so you can plug the matching pairs together. This makes the cooler easy to disassemble for cleaning and maintenance, and foolproof to reassemble.

Solder and crimp a connector for the power input to the logic board that matches the output of the power supply brick.

In the center of the board, connect the blue, red, and green LEDs, respectively, to GPIO pins PA7, PA6 and PA5. The black wire goes to ground.

NOTE: Since all the inputs are used up, you’ll wire the “wine is full” float sensor directly to the LED pointed out the back of the cooler, later in Step 23.

We had to play with our pump voltage to get the desired speed. Although the pump was rated for 12V, using 5V gave us the perfect flow rate to match the water flow rate. So, we soldered a 7805 voltage regulator on the board to get us there. The gravity valve runs directly off 12V.

In this photo, all red wires are power, all black wires are ground. The heavy red and black wires extending to the top are 12V and ground coming into the board.

Along the right edge in this view, the red wires are tying one end of the terminal block high, to 5V, so that when a float sensor is triggered and closes its circuit, the microcontroller can detect a signal going high.

The black wire below and to the left of the chip is the grounding of the black LED wire from Step 13.

The voltage regulator hanging off the board gets 12V from the red and black wires going to it, and has 10µF electrolytic capacitors on both the input and output for stable operation.

It may be useful to refer to the board schematic: https://www.olimex.com/Products/AVR/Development/AVR-IO-M16/resources/AVR-IO-M16-SCH-REV-A.pdf

Wrap Teflon tape around the end of the metal tube going to the cold water valve. Attach a 34″ length of 3/8″ tubing and use a hose clamp lined with a thin piece of rubber to secure it in place. The other end of this tube will connect to the pump’s output barb.

Similarly, clamp a 23″ length of 3/8″ tubing to the metal tube coming out of the side of the water reservoir. The other end of this tube goes to the input of the gravity valve.

Replace the water reservoir in the chassis. Attach the opaque white tubing coming from the hot water valve to the bottom of the reservoir, using 2 small zip ties to secure it.

Attach the float sensor with a 4″ extension to the tube inside the water reservoir using a ziptie. Feed the wires through the tube and crimp a connector on.

For the “water is empty” sensor, attach a straight float sensor to the metal vent tube that runs into the water reservoir.

Anchor the sensor with a zip tie, and run its wires out through the tube.

Connect the power supply and attach the pump lid underneath the metal shelf using 2 machine screws and nuts.

Stuff the pump container with bubble wrap or foam around the pump and use the flaps of the lid to lock the container in place.

Attach the tube coming from the cold water valve to the pump outlet.

Feed the gravity valve’s wires up through a corner hole in the plastic shelf, and then mount the valve in the hole. Attach 1/2″ couplers on both sides using Teflon tape.

Run the flexible sprinkler riser from the bottom coupler through the hole in the metal shelf.

Attach a 3/8″ barbed fitting to the top coupler and connect the hose coming from the water reservoir to it.

Attach a 3/8″ barbed fitting to the bulkhead and glue it in place with silicone, since the inner threads are straight and not tapered.

Set the assembly on the metal shelf and connect a 14″ length of 3/8″ tubing from the bottom barb to the wine pump inlet.

Download the W2W code from GitHub at git@github.com:partyrobotics/water-to-wine.git or https://github.com/partyrobotics/water-t… and then upload it to the microcontroller.

Attach standoffs to the logic board and use double-sided tape to attach it to the inner wall of the chassis in an accessible spot.

Mate all the connector pairs. Connect the switch and reattach the top cover.

Put a 3gal water bottle in the lower compartment with the flex riser going to it from the gravity valve. Unfortunately, the standard 5gal size doesn’t fit, so use the 3gal size for easy swapping.

Assemble the back cover by attaching a bulkhead fitting through the large hole and attaching a right-angle barbed fitting to the bulkhead.

Attach a length of tubing to reach down about halfway into the wine reservoir, about 10″.

Attach the “wine is full” LED to the water reservoir using duct tape. Connect the LED to the float sensor in the wine reservoir lid and make sure it lines up with the hole in the back cover.

Attach the cover and grate with their original screws.

Slip-fit about 8″ of tubing onto the bottom of the funnel, and on the other end attach a 3/8″ barb to a 1/2″ NPT fitting. This threaded end fits into the wine port bulkhead for party in-flight refueling.

Power up the machine. All the lights flash briefly to let you know the code is running properly and all the LEDs are hooked up. The code implements a simple state machine with all the inputs and outputs. There are 5 main states: Idle, Dispense, Out of Water, Out of Wine, and Out of Water & Wine.

The top green LED is on whenever the machine is on. The blue LED lights up when water is out, and the red LED when wine is out.

Test that the sensors turn the appropriate LEDs on, then fill with water and wine, checking for leaks. The first time the pump is run, it will take about 30 seconds to prime; this is normal.