# Design choices, components, and verification

The small board makes the inspection workstation's two contact states visible without pretending to control its axes or camera. It uses only passive dry-contact loops. R1–R3 are generic 1 kΩ 0805 resistors, D1–D3 are Würth Elektronik `150080RS75000` red 0805 LEDs, and J1–J3 use KiCad's 2-pin 2.54 mm vertical header footprint. H1–H4 are 3.2 mm non-plated M3 clearance holes. The native BOM is `BOM.csv`; a purchasing-qualified resistor order code, specific connector mating assembly, fasteners, and PCB laminate are intentionally unresolved.

The [Würth LED datasheet](https://www.we-online.com/components/products/datasheet/150080RS75000.pdf) identifies the 0805 red part and lists a 2–2.4 V forward-voltage range at 20 mA. The [Vishay D/CRCW-P datasheet](https://www.vishay.com/docs/20009/dcrcwp.pdf) shows that a representative 0805 1 kΩ resistor is in range and rated 0.125 W at 70 °C under its stated PCB/temperature conditions; the calculated 25 mW fault-branch ceiling is below that nominal rating, but does not qualify a substitute or thermal design. The [Würth 61300211121 header datasheet](https://www.we-online.com/components/products/datasheet/61300211121.pdf) illustrates a possible 2-pin 2.54 mm vertical header family. The selected generic KiCad footprint and its 1.0 mm finished holes still require a chosen part's actual pin and tolerance check before fabrication. None of these manufacturer parts has been physically fitted or tested here.

The PCB's 80 × 60 mm outline, four-hole 70 × 50 mm pattern, routed tracks, top silkscreen, and connector labels are in the editable `.kicad_pcb`. The `.kicad_pro` sets 0.20 mm minimum copper clearance, 0.15 mm minimum silkscreen clearance, 0.50 mm minimum copper-to-edge clearance, and 0.50 mm minimum hole-to-hole clearance. The `erc.json` and `drc.json` files retain the full KiCad 10.0.6 reports. The DRC included schematic parity and all-track connectivity and found no violations or unconnected items; ERC found no violations. KiCad's standard ignored categories are disclosed in those reports. This verifies software geometry and net agreement only. CAM exports are supplied for inspection, with no supplier rule review, 3D connector clearance check, assembly review, environmental check, or energized measurement.

The circuit and board layout are original work for this cookbook extension. Selected KiCad symbol and footprint snippets are vendored under their upstream terms, described in `KICAD-LIBRARY-LICENSE.md`. This work is separate from the original model-produced inspection-workstation artifacts, which remain unchanged as provenance records.