Open Hardware Files: A Fuji75 Keyboard PCB, Drum-Machine Timing, and More

November 5, 2026

A replacement keyboard PCB, a timing modification for a vintage drum machine, a two-computer keyboard-and-mouse switch, and a USB-connected LTE modem make up this edition of our open hardware roundup. Each project provides editable schematic and PCB files, giving makers something to inspect and adapt beyond manufacturing outputs.

The Fuji75 design and DX TimeShift have new or substantially updated engineering files dated November 5. KMSwitch and Koppar LTE Modem are recent additions from the preceding week. All four are early designs: available source files should not be mistaken for a tested product.

Fuji75: A Replacement PCB for an Existing Keyboard

Fuji75 replacement PCB, shown as a source-derived 2D top view from commit 484da984c1ba. This editorial projection is not a photograph or KiCad screenshot. It shows top-layer tracks, pad and hole positions, and board cuts; copper pours, back-side routing, most silkscreen text and 3D parts are omitted. The source has not been independently validated for manufacture. PCB design: Brian Lai (blai30), CERN-OHL-P-2.0. Footprint contributors: marbastlib and the KiCad library community. Source-derived editorial projection prepared for Tindie Blog. Pinned source · License.

The Fuji75 project is a hot-swap replacement PCB for the Sakura Workshop Fuji75 keyboard. Its RP2040 controller and per-key RGB lighting are designed around the stock case, plate mount, USB daughterboard, and cable. The bottom-right modifier arrangement differs from the stock layout, so builders should check the proposed key layout before committing to a build.

The November 5 update changes the USB power-protection circuit and stabilizer spacing. The engineering files first appeared late on November 4, so this is a design update rather than a November 5 debut. The source includes KiCad 9 schematics and a two-layer PCB saved in KiCad 10; the author recommends opening the project in KiCad 10. The hardware is licensed under CERN-OHL-P-2.0.

Before building: the author has not verified the daughterboard connector pinout with a multimeter. The generated schematic and modified footprints also need review. We have not run design-rule checks or tested a physical board.

Read the project notes · Browse the editable engineering files

DX TimeShift: A Snare Delay Knob for the Oberheim DX

DX TimeShift rev A bare-board engineering render from the project repository, not a photograph of built hardware. The design targets the Oberheim DX 1721A board and had not been bench-tested on a real drum machine at this snapshot. Image: DX TimeShift project owner and contributors (sabrehagen), CERN-OHL-P-2.0. Pinned source · License.

DX TimeShift proposes a new control for the Oberheim DX drum machine: a knob that delays the snare trigger relative to the sequencer. The delay is specified in beats rather than milliseconds, so the intended timing relationship follows tempo changes. An Arduino Nano and a small add-on board handle the modification.

First publicly released on November 5, the project includes editable KiCad 9 schematics and a two-layer PCB under CERN-OHL-P-2.0. Its documentation covers the build, installation, and measurements still needed before use.

Before building: the design targets the plain DX with a 1721A main board, not the DXa. It has not been bench-tested in a real drum machine. Every ribbon-cable conductor needs a continuity check, and the Nano should be removed before USB debugging to avoid back-powering an installed, switched-off DX. Working inside vintage mains-powered equipment calls for a qualified technician. The author’s ERC/DRC claims have not been independently rerun for this roundup.

Read the project notes · Browse the editable engineering files

KMSwitch: One Keyboard and Mouse, Two Computers

KMSwitch variant B rev 1.0 front-layer PCB export, with two RP2040 chips. This is a design view, not a built-board photograph; the project says both variants are untested on physical hardware. PCB view: Kourosh Torabijafroudi / KooroshTorabi, CERN-OHL-P-2.0. Pinned source · License.

KMSwitch is designed to move a USB keyboard and mouse between two computers without installing host-side software. Two RP2040 controllers communicate through a digital isolator. The project offers both a carrier board for RP2040-Zero modules and a version built around discrete RP2040 chips, giving builders two different assembly routes.

A November 4 update added USB ESD protection and RGB indication for variant B. Both variants provide KiCad 7 schematics and two-layer PCB files; their shared libraries live in hardware/lib. The hardware and enclosure use CERN-OHL-P-2.0. This is a recent-week addition, not a new November 5 release.

Before building: neither variant has been tested on a physical board. The author warns that variant A can back-feed approximately 4.7 V into a switched-off computer through the module’s USB power connection. Check the RP2040-Zero footprint against the actual module before ordering, and treat switching and isolation behavior as design intentions awaiting hardware validation.

Read the project notes · Variant A files · Variant B files

Koppar LTE Modem: A Phone-Line Interface Over USB-C

Koppar LTE modem schematic from the pinned repository, rasterized from its published PDF. The sheet is marked Rev A, while the README calls the current design Rev B. The board had not yet been built and tested, and the USB sound-card firmware was not supplied at this snapshot. Schematic: Koppar (Koppar-AI), CERN-OHL-P-2.0. PDF-to-PNG rendering prepared for Tindie Blog. Pinned source · License.

Koppar LTE Modem combines a Quectel EC25-EUX cellular module, USB hub, and RP2040 on a four-layer board. The proposed USB-C interface brings LTE data and serial control to a computer, while the RP2040 is intended to expose call audio as a USB microphone and speaker.

First publicly released on October 31, the project provides editable KiCad schematic and PCB files under CERN-OHL-P-2.0. The author recommends KiCad 10. It joins this edition as another recent-week engineering project.

Before building: the author reports that boards are being ordered, not that a working prototype has been demonstrated. USB sound-card firmware is still to come, and VoLTE depends on the module firmware and carrier support. The README labels the design Rev B, while the inspected schematic and PCB title blocks still say Rev A; confirm the intended revision before fabrication. We have not validated the hardware or its cellular compatibility.

Read the project notes · Browse the editable engineering files

Explore the Sources Before Ordering Boards

The links above point to the fixed repository revisions reviewed for this edition. They open engineering directories, where individual files can be downloaded; they are not preverified one-click project archives. Keep project libraries and license notices with any files you use, and review upstream documentation and current changes before starting a build.

This roundup is based on the November 5 engineering-file report, with coverage through approximately 6:04 p.m. Pacific time (America/Los_Angeles). The reviewed sources included Hackaday, Hackster, CNX Software, and GitHub. Verification was limited to static inspection of editable engineering sources and documentation. No project code was executed, no independent ERC/DRC run was performed, and no physical hardware was tested.

source https://blog.tindie.com/2026/11/open-hardware-files-a-fuji75-keyboard-pcb-drum-machine-timing-and-more/