Kdb v1

Lambda keyboard

A custom 36-key wired ChocV1 split keyboard.

Note : this keyboard is my first design, and while taking it as an inspiration can be a good idea, please think before building exactly this design : there are a few flaws that I wrote about below.

Building the keyboard

Components

To build the keyboard, you'll need :

• 2 RP2040-Zero micro controllers
• 2 4-pin mini DIN connectors
• 5 YS-SK6812mini-e LEDs (optional, the keyboard will work without them)
• 36 Kailh hot-swappable sockets
• 36 Choc v1 (and not Choc v2 !!) switches
• 36 Choc v1 keycaps

The keyboard is diode-less !

You can also design your own case, but I did not bother.

Price

Ordering everything in France, including soldering tools, it cost about 110 €, where approximately a third was for electrical components and the PCB, a second third for key caps and switches, and the last third for shipping costs.

Firmware

This repo also contains QMK firmware for this keyboard, using the BÉPO french layout. The keyboard layout was inspired by Miryoku, and you can view it on keyboard-layout-editor.com.

About the project

Why design yet another split keyboard ?

I fell into the rabbit hole of custom split keyboards, and with all the summer holidays in front of me, I couldn't hold back. It was a fun project !

I chose to make my own design because none where satisfying all my requirements, which were :

• Exactly 36 keys, I was afraid to go with only two thumb keys, but still wanted to go with few keys.
• A layout with enough stagger for my pinky.

With enough research I maybe could have found something, but designing it myself was far more interesting.

If you want a split keyboard, you can definitely think about creating your own ! It is not as difficult as it would seem, and this journey is well documented and there are a lot of tools to make your life easier.

Why lambda ?

I like this Greek letter, and my name starts with an L.

Inspirations

• the Corne keyboard and the TOTEM keyboard for the layout (among others)
• axhixh/mini-kbd which helped me a lot to figure out the PCB design.

What would I change ?

As my first design, nothing is perfect, and here are some things I would change for a future design.

A different connector

I like that the mini DIN protects my keyboard from shorting, but the cable is really bulky. I'll think about changing to USB C next time, or just TRRS, even with the lack of shorting safety.

4 rows instead of 3 to make writing french accents easier.

Writing in English is not a problem, but in french with accents everywhere I find it painful to constantly use layers. It is possible and can even become reliable, but for now I couldn't really get used to it (maybe I haven't used the keyboard enough yet...).

Also, for coding, where a lot of special symbols are needed, a couple more keys could be useful.

More leds

Only 5 underglow LEDs are not enough in my opinion, you can see their light but there are some "holes". Also, for a future keyboard I'd like per key lighting as well, even if it requires more work.

An OLED display

Seems fun.

Writing JLCJLCJLC on the PCB

Without this text, JLC PCB wrote a random number in a random place on my PCBs... Fortunately it does not look that bad.