I've tried a lot of weird things, and they don't often work out, but maybe there's something to learn from it - or maybe someone else can pick up the pieces and make something useful.
I wanted to use this space to talk about one project in particular that I was playing with, but it didn't really work out. It might, but I kind of lost the impetus to keep going with it. I know I've tried a few other oddball things in the past, but never posted about them, because making a thread for some experimental thing that doesn't go anywhere seems kind of wasteful, so I intend to keep posting stuff into here.
Anyone else is welcome to share in here as well.
So, on with the show...
I like working with PCBs, it makes things neat and tidy. Hand wiring is cheaper. I saw those Kailh low profile Choc switches and I wanted to make something, but I didn't want to make a huge PCB for it, so I ordered some last December (2017) and I set about trying to come up with a way to get the best of both worlds.
I blocked out the pattern of a typical stagger, taking into account key sizes of those Kailh Chocs, and I found the patterns of how the keys lined up. It turns out, it's not really all that bad. It's messy, yes, but it works.
So I had some bits made. DirtyPCBs to the rescue. $13 for ~10 little strips to make a keypad (I think I got 12 of them, I can't remember).
I have some weird keypad layouts, so you can do a half-key vertical stagger with these, but otherwise it could be made into a 6x[whatever] grid. The strips have pad/connectors at the edges (I wanted castellated edges, but ran into being cheap about manufacturing) and 4x M2 mounting holes in the corners.
The rows connect together by bridging the pads along the vertical edge. The columns would connect with wire from the pads at the top or bottom of each strip. There are pads to pass VCC & GND through to each strip, and a pad for LED control. The LED control is a simple NPN Diode circuit, that turns all of the LEDs on, on the strip.
I wasn't sure what to do about a controller, so I just made a simple ATMega32U2 controller that fit into the same width as one of the strips, and had some of those made as well. I'm sure there's a better option, if this is half PCB/half hand wired, but this was my quick solution. I tried to be inspired by bpiphany and use some 74HC138 decoders/demuxers to expand out the number of pins, but I must have gotten something wrong there, because I just couldn't get that to work. Oh well. That's failure #1.
For testing, I didn't bridge all of the pads to hold the strips together, just some of them - and really it was enough to add quite a bit of stiffness to the assembly.
The LEDs worked out just fine, so that was good, I was happy with the way this was turning out, I just needed a different controller solution.
I decided to make some more pieces.
And then I realized I did something wrong.
*sigh*
If you look back at the design, there is an A and an A' layout.
They're identical, just flipped 180 from each other. That was part of my plan, just flip over the strip, and voila! Well, during all of the layout of all of the different positions of everything, I forgot about this, and I didn't account for flipping over the strip in the placement of the LEDs... or the resistors... or the diodes... or the LED control transistor... or... anything at all. So close... yet... not close enough. That's failure #2.
So here's all sat for... 8 months? Overcome by events, and I've since determined that I don't need the whole thing, and it would probably be easier for me to just create the keypad part (the part I really want) as a single PCB and put the controller on the back of that.
Maybe something could come of this, I don't know, but I've lost the inspiration to continue with it.
At least the switch footprints work!
