Although the pressure regulator will work just fine if it is assembled like my first prototype (see previous log), I want a cleaner, more integrated solution. That means designing a manifold, which will be a block of machined aluminum with ports for the input, output, pressure sensor, and valves.

It must be possible to make it with a mill, maybe even just a drill press. It should also be as small as possible while still leaving space for the two valves, the pressure sensor, and a PCB which will house a microcontroller along with all the components and connectors needed to drive this thing.

The design is not finalized yet -- I will need to design the PCB first, and make sure that everything will fit as intended -- but here is my current idea for the manifold:

The barbed connector on the right is the outlet. The one on the top is to connect tubing to the pressure sensor. The threaded hole on the left face will be plugged; it's just there to make it possible to drill the hole for the top barbed connector. Hidden on the left-back side is the inlet connector.

This may be a bit more clear with the hidden edges visible:

Before I had gotten this far, I made use of our university's makerspace (think[box]) and their fancy 3D printer that can print translucent material, to have a better idea of what the manifold would look like, and weed out any glaring errors. This earlier version is a little smaller (38 x 38mm rather than 50 x 50), and didn't include the top-side connector for the pressure sensor:

Besides the small amount of support material that didn't dissolve, it looks great and is very helpful in visualizing what goes where. I am waiting on more valves to arrive, but here is what it looks like with the one proportional valve I currently have:

I still have to refine some parts of this design, which will be easier to do once I have finished designing the PCB. Eventually, I want the PCB to stack on top of the valves. I am also trying to lay it out in a way that makes it possible to stack these regulators. They will end up being a little under 50 x 50 x 50 mm^3, so stacking one on top of another would be useful at least in my application (where they will reside in a box ~130mm tall).