DIY Modular Synth Case: Power Distribution

So, I’m building a case for my home-made modular synth. Not this case, which I made just a couple of months ago when I was first dabbling in DIY electronics. Oh no, I’ve outgrown that one already. I’ll be keeping it, though, as a test frame for the workbench.

No, I’m talking about this case:

13U x 2 row modular case

2 rows of modules, each row 13U wide. So, potentially, 26 x 1U modules.

Believe it or not, I’ve already got 17U in the build process… so this one’s probably going to fill up pretty fast, too.

At the moment I’m waiting on parts in order to get this build moving – I’m having a whole bunch of blank aluminium module panels laser-cut , and until they arrive I can’t see the tolerances in the cutting process. Which means I can’t finalise dimensions for the frame they’ll mount into. Which means I can’t finalise dimensions for anything else.

But, that doesn’t stop me putting together some useful things that I’ll need for this project. I’m designing the power supply, for example (internal, this time; no wall warts allowed in this beauty). While that’s going on, what I’ll definitely need is a means of transporting that power to the various modules when they’re mounted. Usually, this is done by means of a bus board or flying bus cable. The power is distributed to a whole bunch of sockets that the modules plug into. The sockets are either mounted on a long and skinny circuit board (bus board) or on a long and skinny ribbon cable (flying bus). Both, in my miserly opinion, are unreasonably expensive when bought ready-made (the flying bus cable in my previous little DIY case was the single most expensive component in it).

So, once again, I’ve set out to build my own. I’ve built a series of bus boards, each with 5 Eurorack-style 8×2 IDC connectors, connected to each other by short jumper cables. The whole thing was stupidly cheap to build. The boards are a standard size stripboard (and therefore cheap) and I bought a bulk pack of sockets on eBay (and therefore paid very, very little). The cables I put together from hookup wire and DuPont crimp connectors that I have as stock anyway.

IMG_6702.JPG

These will mount on the two wooden battens that you can see in the middle-back of the case – ideally placed for powering modules in either the upper or lower row. 5 boards fit nicely in the 600mm or so that I have to work with, which means there’ll be 25 connectors available to power my modules. Some of my 26U of modules will be double-width 2U modules, so I should actually end up with connectors to spare.

I settled on the Eurorack power standard for a number of reasons:

  1. If I ever build a custom case for my Eurorack-format modules, I can use the same design to power them
  2. I could potentially mix-and-match 5U and Eurorack modules in the same case
  3. Eurorack power cables are cheap and easy to make
  4. It’s easier to adhere to an existing standard than try to enforce your own
  5. I already understand the Eurorack power format and I’m too lazy to learn a new one

I suspect this might be the simplest, single, electronic thing that you can build for a modular system that’s of actual use.

All the docs are below in case anyone wants them.

Schematic

Power Distro schematic

Stripboard layout

Power Distro board

Flipped stripboard layout

Power Distro board flipped

BOM

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