3_8th ortho keeb

Wireless Bluetooth, RGB, 18650 powered, USB C, 39 key, ortho mechanical keyboard.
39 keys is exactly 3/8ths of a full 104 key keyboard.

When I set out to build a custom keyboard, my original inspiration was that it would be a work of art as much as it would be a functional keyboard. Early designs were handwired and consisted of many layers of laser cut acrylic that sandwiched the wires in place. I wanted it's construction to be as much a feature as anything else. The original schematic used MAX7219 8-segment display driver chips to address 4 pin LEDs. I soon realized, with that many connections per key, a hand wired approach would not be feasible. I swapped the LEDs to SK6812 MINI-E RGB ( WS2812B) rear mount SMD addressable leds and moved my design into Kicad.

Here are all the components layed out. (The 3D printed case is not the final design at this time.)

Very standard switch matrix with ortho layout and a single key missing. This will be my Space and Enter key. Or, a double Spacebar depending on layout.

This is the bus of addressable RGB LEDs with a 300ohm resistor to cut down on noise.

I knew from the beginning that I wanted this to be a wireless battery powered keyboard. Since each LED could draw 60mA each I knew I had to size my power traces and power supply accordingly! Because of this constraint the LEDs are powered from the battery via the external Pololu U3V70F5 step-up regulator.

The Nice!Nano is a promicro replacement that supports bluetooth, customizable zmk firmware, and 500mA battery charging and protection.

Routing all the traces while staying within acceptable distances from other traces and holes was the biggest difficulty while designing the PCB layout.

Here is the populated PCB

Each panel of the laser cut frame was a double-sided operation; with indents to embed keys into the surface. This gives a final lower profile, while accounting for the difference between key-height and the acrylic material thickness.

You can see the reliefs for the keys, key retaining latches, and diode legs.

PCB loosely assembled in the frame and case.

All key installed.

RGB test!