Brain (based on Urchin by Duckyb)

My first ever keyboard build was the Ferris Sweep, it's a wonderful keyboard! But I missed a few keys, the ctrl and shift keys on the left side and since I'm Swedish, I also wanted keys for åäö. Apart from this I was also only interested in wireless designs and was not interested in the TRRS jacks etc. The Urchin was the perfect solution for me, but I were still missing those oh so sought after keys. So I decided to make my own version of the Urchin, with a few extra keys and a little tweek to the edge cut to fit them nicely.

The result of this is the Brain, a wireless split keyboard based on the Urchin with 3 extra keys on each side. One extra pinky column with two keys and one extra thumb key. All 5 pinky keys are placed 2mm lower than the original Urchin keys, to make it easier to reach them.

This is a strictly wireless-only design, and is only compatible with ZMK / nice!nano. Only Choc v1 switches + Hotswap are supported!

Features compared to Urchin

• Original pinky column lowered 2mm.
• A new pinky column added with two buttons, also 2mm offset down from its neighbour.
• One new thumb button added.
• Holes that fit Corne Acrylic cover for nice!view.

Feature requests for 2.0

• Raise last pinky column, maybe as much as 7-8 mm. For easier access to both the keys and not only the top one.
• Add back the fourth hole for tenting puck.
• Rotate the diode for switch 17, it's reversed now which causes confusion.
• Change the reset switch B3U-1000P(M) to regular tactile reset switch such as https://kriscables.com/product/tactile-reset-switch/ since it's a pain to get hold of the original reset switch.
• Do a non battery RGB blingbling version? I almost only use my keyboard without battery and a cable like this anyway https://www.amazon.se/dp/B0CYT426GZ?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1

Part list (for both sides)

Required

• 1× PCB Kit (files for it are in releases)
• 40× Kailh CHOC Hotswap Sockets (https://splitkb.com/products/kailh-hotswap-sockets?variant=39472161456205)
• 40× Kailh Choc v1 Switches (https://splitkb.com/collections/switches-and-keycaps/products/kailh-low-profile-choc-switches)
• 40× Keycaps 1u (https://splitkb.com/collections/switches-and-keycaps/products/blank-mbk-choc-low-profile-keycaps)
• 2× nice!nano (https://splitkb.com/products/nice-nano?_pos=1&_sid=0e4cc26b1&_ss=r)
• 40× SMD diodes (SOD-123) (https://kriscables.com/product/smd-diodes-sod123fl/)
• 48× mill-max machined pins (https://kriscables.com/product/mill-max-socket-pins/)
• 2× Pair of female mill-max headers (raised ones to fit battery) (https://kriscables.com/product/mill-max-low-profile-sockets/)
• 2× Lipo battery (301230) (https://kriscables.com/product/li-po-battery-3-7v-110mah/)
  • OR 1x split USB-C cable to use the keyboard without batteries (https://www.amazon.se/dp/B0CYT426GZ?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1) (this also means you could go with "regular" millmax sockets and not the raised ones)
• 2x Power switch (MSK 12C02) (https://kriscables.com/product/msk-12c02-power-switch/)

Optional

• 2× nice!view (needs higher sockets to get level above raised mill-max sockets, TODO add exact ones) (https://splitkb.com/collections/keyboard-parts/products/nice-view)
• 2× Reset switch (B3U-1000P(M)) (https://www.digikey.se/sv/products/detail/omron-electronics-inc-emc-div/B3U-1000P/1534338?srsltid=AfmBOop7zspfRjYOQ7LR1wDdW5W1PJkAlY6OWJ5YXfqCBF3_GB-U63jH)
• 16× adhesive silicone feet 8mm (https://www.amazon.se/-/en/Adhesive-Silicone-Semicircle-Transparent-Furniture/dp/B09QSKVBL5)

How do I make this?

Follow the the excellent build guide in the link below. The only difference is the 3 extra keys on each side.

Note that diodes should only be mounted on the "BOTTOM" side of the PCBs.

Firmware

Brain supports ZMK only.

Firmware is provided by the lovely iamDrakkir and can be found in his zmk-brain repo.

My personal fork can be found here if it's of interest for anyone (it has automatic picture generation of the layout for the readme #humbleflex)

3D Printed Cases

Top	Side

Closed	Open

Credits

• Urchin by duckyb
• Logo by Ariyanto Deni
• 3D case by iamDrakkir
• ZMK Firmware iamDrakkir

Featured In

• KBD Issue #122

License

MIT