(Forked from this thread: Free PCBs!(yes actually discourse) - turns out you can get small PCBs made for free!)
Does anybody want to play a bit of PCB golf?
What’s the most useful/cool module core we can build in 100x150mm? White noise machines, mults, maybe even a filter or a VCO?
Not sure how scoring would work, either highest part count, or just most nifty module…
Stacked, or one board? SMD or through hole? Panel or PCB mount pots/jack’s?
I am happy to play along.
edit: @analogoutput No, all the options are there, fastest of which is DHL(2-3 days). I suspect there will be long lead times though for the actual PCB.
I think: One board, through hole, jack and pots can be either molex/pads or mounts, power can either be 10 pin euro or 3-pin molex/pad. 100x150 is too small for “real” Kosmo spec, so this should be just for any kind of DIY synth. Maybe we can award style points for mounted Kosmo-style pots since they make assembly easier.
Scoring concepts so far:
If you wire panel mounted pots and jacks, that’s plenty of space for a module of any format.
Be mindful of things that do take up a lot of space. Things like pots and faders are necessarily space takers cause of finger sausages.
Anybody got any tips for routing? I keep making islands that can’t be reached! 
Try separating horizontal and vertical traces between the two layers . Also, 80 percent of routing is done during component placement.
PS, looking at your 3D model: all non-panel components are usually placed on the back of the module, makes them easily reachable. Also don’t forget mounting holes.
Horizontal traces on the bottom, vertical on the top. Use plenty vias. Also in Route> Interactive Router Settings, change it to push and shove routing and the router effort to high.
I’ve seen it both ways (Befaco Even VCO for example) but that’s my preference. For me that includes the Molex connectors, making the board short and/or narrow enough to route the wiring around it, rather than trying to jam the wiring between the panel and the PCB.
Thanks for the tip! I hadn’t explored vias yet. I think I like power on the back, molex on the front, so I can just use short wires to hold the board up without them wrapping around the sides and possibly bumping into another module on the sides, but that’s preference. I think you’re right about the other bits though, especially the ICs.
You have enough room on that board to shift the components a little and shorten it, so running wires over the ends is easy. Zip ties will keep them from straying out to the sides. As for using wiring and Molex to support the PCB, yeesh, no. That’s asking for trouble down the road. Use standoffs or a bracket or something meant to take the strain. The weight of the board and power cable isn’t negligible. At the very least forego the Molex and solder the wires, if you’re going that route.
I put all the components that fit on the front side of the module (between the pcb and the panel), so that they are a bit protected. Apart from the power socket, obviously xD. I have first seen it on the Kassutronics builds and thought it very clever 
But there are issues: electrolytic caps can be quite large, so they don’t fit and then I need to lay them on the side (or buy smaller caps, but that’s annoying too), which is not really elegant. And yeah, it’s a bit harder to troubleshoot, if you don’t see the components. But I usually remove the panel anyway when something is not working. In the end it’s mostly preference, I guess… I like the “cleaner” look with the components hidden away
Or just solder those on the back side.
I have trouble figuring out what people are trying to “protect” or “hide” the components from; mice inside the case? But yeah, it’s a personal preference.
Once they are in the case, they are pretty safe, but not while I have them on a full desk where I might dump a new pile of stuff, pushing them off the edge 
It’s probably irrational, but I have an aversion to using any more vias than I have to. Sometimes I catch myself sending a trace all around the Horn rather than using a via, which is silly. But most of the time I can get away with no more than a handful of vias and often none at all. I do find it easier to follow the routing if it’s not flipping sides all the time.
Certainly there’s no reason to add a via for a direction change if the new trace segment doesn’t need to cross another trace, and it’s even fine to put an entire non-crossing trace in the “wrong” direction.
As for fixing or avoiding islands, I guess there’s no substitute for experience. Look for traces you can flip to the other side — maybe two or more would have to flip to make it work — to get the island connected. Try not to put traces so close to pads that there’s no room for the ground plane fill in between, if you can avoid it. Use ground fills on both sides. Then just sticking a via in the middle of an island will often cure its unconnectedness.
My effort - a multiple mixer. Basically Sam’s buffered mult(1->5) and the mini mixer(5->1). I’ll use it to split the 1v/oct CV from my CVpal into 5 eventual oscillators, and then to mix the final output into the audio interface after each has been filtered etc.
It measures up at 50x100mm, for use in a 10cm module.
files are here:
Hell yeah! A big swing for our first entry!
