This thread deserves a bump!
I finally gave up on making a foot controller out of a nanoKontrol. I used a wireless keyboard instead, which I actually messed up half-way, but I succeeded in making it work as a foot controller.
I started with this, a 45€ 2.4GHz wireless keyboard (with a French layout, AZERTY) that I bought two years ago (and have replaced since).
The conductive traces are on a folded and glued plastic sheet that I had to separate carefully with a thin blade. Notice the ribbon cable that goes from the sheet to the PCB. I tested each key that I wanted to use with a multimeter (one probe on the trace on the sheet, another sweeping the connector on the PCB to find the corresponding terminal) and labelled them with a code to see to which combination of terminals each letter was associated (for instance, A: 8L 4R
, 8th terminal from the left with 4th terminal from the right).
Then I messed up everything (the terminal connector especially) while trying to solder wires on the legs of the connector. For a moment I thought the project was over, but I managed to solder the wires directly on the PCB. Long story short — I got what I wanted and soldered enough wires to have 26 working combinations plus the caps lock key. I cut the wires that did not produce any combination. The result is ugly, but hey — it works!
I labelled the wires and taped them to a piece of aluminium so as to avoid tearing them accidentally from the PCB.
Then I taped the piece of aluminium to the PCB...
... and cut out the battery compartment from the keyboard (and added an on-off switch):
I re-tested everything again, and checked the wires combinations:
Then the layout. I initially planned to make a 4x5 switches controller and bought 20 switches, but finally ended up with a 4x6 layout. Not a problem, I'll add the remaining switches later — the upper row will be 1 2 3 4 7 Capslock. For the time being there will be only 19 switches, as I used one for another project.
Now the enclosure. I used 1cm MDF (3/8 inches). The board itself is 40cm wide, 25cm deep and 6.5cm high (16x10x2.5 inches). There is 7cm (3 inches) between each switch. It is not very refined inside, but it is rather strong.
And finally, after two hours of soldering...
The best thing is that it actually works!
I may change the switches for sturdier ones later, but these ones will do for now. Thanks to all the contributors in this thread who inspired me!