Portable VLF receiver

Custom 9 V alkaline natural-radio receiver for whip or wire antennas, with an earth terminal and mono output to an original ZOOM H5. Circuit revision C now has assigned footprints and a routed 43 × 66 mm prototype PCB incorporating the manual connector adjustments.

Resume work: Latest session handoff. The first board has been assembled and heard through the H5. Next is an internal antenna-base mount using the user's 12 × 6 mm lug once samples arrive. Current lid exports still use the earlier external mount; defer printing them for the preferred internal design.

• Schematic PDF / editable KiCad project
• Enclosure and mechanical fit notes / existing external-mount prototype lid / PCB STEP / FreeCAD enclosure
• Routing notes and validation / top copper / bottom copper
• PCB placement and footprint review / placement drawing / editable PCB
• Revision C changes and enclosure interfaces
• BOM review and substitution requirements
• Circuit explanation, response plot and bring-up plan
• Preliminary DigiKey BOM: approximately $41.72 budget for three receivers, including plugs and resistor strips
• Settled specification and workflow

Open hardware/vlf-receiver.kicad_pro in KiCad 9. The installed Flatpak works; no native installation is necessary. Symbols and footprints are local to the project. The routed board passes DRC with zero unconnected items and zero schematic-parity issues. Sample fit checks for custom footprints and enclosure details remain pending.

Reproduce with python3 scripts/build_schematic.py, the commands in scripts/export.sh, python3 scripts/check_design.py, and python3 scripts/analyze.py. The generator overwrites the schematic: preserve GUI edits in git before rerunning it, and carry intentional changes back into the generator or retire it when hand editing takes over.