Open-source boards designed in KiCad by hmerrett on GitHub, from 2 repositories. A board’s address here is its repository’s there.
hmerrett/HenryFlops
OpenFlops is an Open Hardware implementation of such an emulator, inspired from the ubiquitous Gotek hardware. It is designed to run the FlashFloppy firmware, which gives it several improvements over the original Gotek…
hmerrett/pico506-pcb
A dedicated PCB for the Pico506 ST-506/MFM/RLL hard drive emulator: two-layer, 138 × 74 mm, all through-hole, with real card-edge tabs so it plugs into a period ST-506 control/data cable pair the same way an ST-225 does.