Smart Barrel

These instructions are for a barrel with an electronic fill meter, or "smart barrel." This project involves some relatively complicated woodworking, along with some basic soldering. Here's a list of materials needed for this project:

• 1in x 4in x 8ft wooden plank (2 planks)
• 10ft 5in of metal banding (for hoops)
• 3 bolts and nuts
• 3 gallon water jug
• PCB board and breadboard
• PVC pipe
• 680k ohm resistors (6 resistors)
• 220nf capacitor
• 1nf capacitor
• LED strip
• Arduino Uno
• Wire
• Hot glue

Using the above diagrams, build the circuit and solder it together. I created it first on a breadboard and then did a final version on a PCB board. You could mill your own board for this, but since it was a prototype I just used a PCB.

The first diagram shows the entire circuit along with the water sensor, while the second diagram shows you how to wire the sensor itself. You will notice that the first diagram does not show an Arduino Uno, but you can use one anyway.

Using a table saw, cut down the wood into 1in x 1in x 17.5in staves. Once you have a sufficient number of them you can assemble them in a circle using the hoops. I created the metal hoops by cutting out 3 45in lengths of metal banding and bolting them together. I drilled a hole through the ends of each one, then used a bolt and nut to secure it. The staves will be progressively harder to force in, but once you get the last one in the internal tension should hold the whole thing together. I created a jig in order to keep the staves from collapsing inward while assembling the barrel, but this step is optional.

After the barrel itself was completed, I glued a circular piece of wood about 2in from the bottom to create a ledge for the jug. It also had a secondary effect of creating a compartment for the electronics, which can be accessed using a pivoting bottom. The bottom is easily made by cutting out a thin wooden circle and using a screw to allow it to pivot.

When you've finished the barrel, you need to get the jug ready. I decided that the best way to integrate the sensor was by hot gluing the wires to a PVC pipe and inserting the PVC into the jug. I first assembled the PVC sensor assembly, and the cut a hole in the bottom of the jug. I placed the PVC inside, and then sealed the hole using acrylic sheets and hot glue. This takes some trial and error to get right, but once you are done the jug should we waterproof.

The final step is to put it all together. First, put the jug on ledge and allow the electronics to dangle through the hole. Then you need to secure the jug in place. I did so with a series of wooden pieces that prevented it from sliding, but other methods would work too. Next, the jug needs a PVC extension in order to make the top fit on. Once that is added, cut out another wooden circle like the one you used for the bottom, except put a hole in the center slightly wider than the PVC pipe. I then simply secured the top with 4 screws and put a PVC endcap on as a lid.

Once you have added the top, your barrel should be ready to be filled! Just hook up a 9V battery to the circuit and start pouring in water!

For more pictures, visit this folder: Pictures

For a more detailed workflow, visit this project journal: Project Journal

For a premade list of materials with links, visit this spreadsheet: Materials