Post by ampersands on Mar 6, 2023 1:00:37 GMT
We did it!
As always, big thanks to keurslagerkurt for doing all the work to kick things off and inspiring the whole project.
I hit a few bumps along the way, made three separate prototypes, melted a button or two with the soldering iron and destroyed at least one Pico with poor power delivery.
But ultimately crammed all the EuroPi functionality into a 2U AE format (what a squeeze!)
Under the hood - I tried in vain to find two-sided board in the correct size and ended up fudging it by using bits of thin protoboard cut to shape and mounted back-to-back where I needed to solder something in 'backwards'. It worked a lot better than i expected actually. The red board is from the official TW DIY kit and was left over from something else but turned out to be a godsend; it's double-sided and has central power and ground rails so it was perfect for mounting the op-amps on.
Rear side is a million times neater than previous attempts. I knew the amps and Pico needed to be detachable & mounted on headers for space reasons but it took a while to figure out a good way to do it.
Sideways. It's tight! The bus connector only just fits below the op-amp board. I didn't measure that bit when planning, so phew!
The whole thing ends up sitting ever so slightly higher than an official TW module, but not so much that it looks silly.
So far it all seems to work really well. I'd love to see some other people build the same - maybe when i'm confident in this build we could put together a kiCAD layout so people could order PCBs?? That would simplify the build a lot, as most of the complexity comes from using wire to route connections here and there. Otherwise there really isn't a crazy amount of parts needed, off the top of my head:
2x momentary push buttons
3x op amps + chip holders
Various resistors - a £5 box of mixed values will have everything needed
Nice AE pin headers x2
Generic pin headers for connecting the boards and making a plug for the bus cable (Pi Hut has a bag with a bunch of sizes which is perfect, just cut em up if needed)
6x 1nf caps
Legs & screws and whatnot for mounting
That's about it!! I'll draw up my version of the schematic when i get the chance.