Ad3-feature module

AD3 modular test rig

Passive, single-sided 100 × 100 mm baseboard for an Analog Discovery 3 flywire cable, a 170-point breadboard or the included 70 × 90 mm plug-in feature module. Nine populated baseboard footprints plus two removable source shunts; every purchased PCB component is matched to data/dtu_component_shop.csv in data/bom.csv or module/bom.csv.

Assembly renders

The plug-in configuration adds a low-pass filter, attenuator, selectable loopback paths, signal terminals, two buttons and two LEDs. Remove the breadboard before fitting the module. See the module assembly and test guide for wiring, soldering and AD3 commissioning.

The module uses a printed support and taller storage cover. Download the Blender assembly, support STL and tall cover STL.

The original breadboard configuration remains available. These are design renders with illustrative component bodies; physical hardware and first-print fit have not yet been verified.

Open hardware/ad3-test-rig.kicad_pro in KiCad 10. Start the showcase with python serve.py, then visit http://localhost:8081.

• hardware/: schematic, routed board, project-local footprint library and rules.
• hardware/production/: unmirrored B.Cu Gerber, outline, silkscreen and drill data.
• enclosure/: Blender source, editable scene, base/cover STLs and assembly GLB.
• website/: local showcase, interactive pinout, model inspection and assembly checklist.
• bench/: commissioning procedure and opt-in WaveForms SDK loopback test.
• tests/: generated electrical, inventory and mechanical reports.

Design decisions

J1/J2 are male 15-pin banks for the individual female flywires. J3/J4 are matching female sockets, 60 mm between bank centre lines, for patching or a future module. Pins 1–15 run toward increasing PCB Y. All four grounds are common. CH1− and CH2− remain independent differential inputs. The AD3's positive and negative supplies pass straight to J3/J4 pin 4.

J5 is bench input (+, GND, −), J6 is selected-power screw terminal and J7 a selected-power module socket. JP1/JP2 choose AD3 (1–2), bench (2–3), or disconnected (no shunt). The selected rails do not replace raw supplies on J3/J4. A future module can ignore bank pin 4 and use J7 if it needs selected power. A module and the breadboard may occupy the same central space; remove the breadboard before fitting a full-width module. The optional feature module is now included in module/: a separate 70 × 90 mm KiCad project with analog experiments, buttons, LEDs, a printed support and taller cover. See module instructions.

Fabrication and fit

B.Cu tracks are 1.0 mm wide; global copper clearance is 0.85 mm. Header pads were narrowed to 1.6 mm with 1.0 mm drills: their 2.54 mm pitch leaves 0.94 mm copper clearance. All joints are soldered from the bottom; no vias, top tracks, plated-through connectivity or wire bridges. Through-hole pads appear on both KiCad copper layers, but only bottom copper is fabricated. No mask is needed. If the blank has copper on both sides, remove the unused top copper rather than leaving it shorting the component leads.

The 100 × 100 mm finished outline assumes stock large enough for fixturing and an outline cut; a blank exactly that size cannot provide sacrificial edge stock. CAM must use the actual tool and machine settings. A nominal 0.8 mm cutter has only 0.05 mm total margin against the 0.85 mm rule. Verify tool runout and a small milling coupon before the board. Gerbers are not machine-ready motion programs; perform the bottom-view mirroring once in CAM/fixturing, not in these files.

The shop CSV names generic parts, not manufacturers or exact mechanical sizes. Assumptions to check before milling: headers 2.54 mm pitch; terminal blocks 5.08 mm pitch with pin/housing geometry fitting the vendored Phoenix-style footprint. No claim of measured fit or actual shelf quantity is made. The breadboard, existing AD3 cable, patch wires, PCB blank and print filament are user-selected equipment/fabrication supplies; the breadboard is not listed in the CSV. No extra purchased fasteners are needed.

Enclosure

PETG suggested for the four flexible retention fingers; 0.2 mm layers, at least 3 perimeters. Base 112 × 112 × 14 mm; cover 117.6 × 117.6 × 34.4 mm. STLs are millimetres and already oriented with their solid floor/roof on the build plate. Verify slicer dimensions. The PCB rests at Z=8.4 mm, leaving 6 mm above the inside floor for solder tails. Trim tails below 3 mm. A front-wall notch clears the bench terminal wiring. Four 2.8 mm printed locating pins enter the 3.2 mm PCB holes; snap fingers retain the edges with 0.4 mm nominal clearance above a 1.6 mm board. Cover is for storage with all cables removed. First-print mechanical fit remains untested; tune clip and cover clearances to your printer. The Blender component bodies and breadboard are illustrative, not manufacturer-certified CAD models.

Rebuilding

Python 3.14 with KiCad's pcbnew and sexpdata, KiCad 10, Blender 5.2 and numpy for bench analysis were used. scripts/build.py uses the local schematic drawing toolkit at /home/mads/Projects/claude-skills/kicad-schematic/scripts; set that path in the script on another machine. Generated KiCad files are standalone and do not need the toolkit to open or edit. Run scripts/build.py only to regenerate from its design specification; it overwrites generated hardware files. After hand edits in KiCad, export and validate without regenerating. python scripts/export.py refreshes ERC/DRC, schematic PDF and fabrication exports after edits. python tests/verify.py verifies inventory, pinout, copper-layer constraints, print meshes and loopback fault rejection. scripts/geometry.py refreshes layout data for blender -b --python enclosure/build_enclosure.py.

Pinout and instrument reference: Digilent AD3 guide. The included pinout image comes from the installed Digilent WaveForms documentation. Stock footprints derive from KiCad libraries (CC-BY-SA 4.0 with library exception).

Optional feature module

The baseboard schematic, copper and outline are unchanged. The new module replaces the breadboard while fitted, retains all AD3 signals on top sockets, and provides patchable filter/attenuator/loopback and digital test sections. Its purchased components also match the original shop CSV, with exact category matching for ambiguous part names. Use the dark-mode showcase for module placement, resistor colour codes and jumper states. Module hardware and first-print fit remain unverified; digital and analog commissioning instructions and SDK scripts are in module/.