Eu sensor board

Sladdseg

Sladdseg is a wall plate that replaces a light switch on a circuit where every bulb is a smart bulb (here IKEA Matter-over-Thread). The bulbs stay powered. An IKEA BILRESA scroll-wheel remote sits recessed in the plate and lifts out; behind it a rocker switch cuts line and neutral to the circuit. The full edition adds mmWave presence, temperature, humidity and push-to-talk voice at the switch location, powered from the box.

North American single-gang (Decora)	European round flush box (DIN 49073)

Two variants: NA for a 2 × 3 in single-gang box, EU for a Ø60 / 68 mm round flush box. Printed parts and small PCBs, all generated from this repository.

Design

• The remote is the control. The BILRESA sits in the plate, held by a magnet.
• The rocker is the fallback. Hidden behind the remote, it breaks line and neutral to the load and the plate's electronics; off and on brings the lights up without Home Assistant.
• Mains side: a certified rocker (Marquardt 1802.2504 or E-Switch RA412C1100), a certified 5 V supply and push-in terminal blocks, on a board designed to IEC 62368-1 spacing.

Editions

The barrier and the mains board are the same in every edition.

What is on the plate

From the room inwards:

Operation

Day to day the lights are controlled wirelessly: the remote, Home Assistant, the IKEA app or a voice assistant. The rocker switch is for two cases:

• Controller or network down: turn the rocker switch off and on. The bulbs restart and come on at their power-on setting, which must be set to "On" in each bulb.
• Safety: off cuts line and neutral to the fixtures on this circuit and powers down the plate's electronics.

Warning: the rocker switch does not replace the breaker. Turn the circuit's breaker off, and check with a tester that the wires are dead, before working on any wiring, the plate or the fixtures.

Warning: polarity matters. Connect the supply's line to L IN and its neutral to N IN, as marked on the board, with the load wires on L SW / N SW (NA) or L LOAD / N LOAD (EU). Earth goes to PE on the NA board; on the EU plate it is joined in the box with a WAGO 221-412 lever connector. The PSU's fuse is in the line; with line and neutral swapped, the fuse sits in the neutral and line stays on the PSU when it blows. Confirm which supply wire is line with a tester before connecting.

The microphone (full edition) streams to Home Assistant's Assist pipeline only when listening is started from Home Assistant. There is no wake word and no speaker.

North American single-gang / Decora

Full edition:

Remote in place	Remote out, rocker switch exposed

Half-section	Back, box side

Exploded, front to back: remote, face plate, barrier, sensor board with the MSR-2, pin board with the spring pins on two spacer posts, four nylon standoffs, mains board.

Switch edition:

Remote in place	Remote out, rocker switch exposed

Batt Free edition:

Remote in place	Remote out, rocker switch exposed

European round flush box (DIN 49073)

The barrier closes the box and carries the remote; under it the mains board at the rocker's seat and the pin board; on the wall the sensor board in a printed carrier, and the face plate snapped into the carrier.

Full edition:

Remote in place	Remote out, rocker switch exposed

Half-section	Back, box side

On the back: the mains board with its two WAGO push-in blocks (grey) and the PSU (black); the pin board sits between it and the barrier.

Switch edition:

Remote in place	Remote out, rocker switch exposed

Batt Free edition:

Remote in place	Remote out, rocker switch exposed

Battery-free back cover

For fixed installs: the printed cover replaces the remote's own and runs it from the plate with no cells; lifted out, the remote is off. Two pads behind windows in the cover's back take 5 V from the spring pins, and a 3.3 V regulator on the cover's flex feeds two spring fingers on the remote's battery contacts. Not a charging circuit; it holds no energy.

Cover with its flex	Exploded in the EU plate

Building from source

CAD in Python (build123d); boards in Python to KiCad 9 projects (ERC and DRC clean, schematic parity); slicer projects; PCBWay packs; order lists with live DigiKey and Mouser stock. make check includes a test that no air path leads from the mains volume through the printed barrier to the room.

make system-deps     # once, Ubuntu 24.04 (KiCad 9, headless slicer libs)
make setup           # once (venv + pinned ElegooSlicer)
make pcb             # boards: ERC / DRC, STEP, fab packs
make cad check       # CAD to build/, all checks (shared parts, NA, EU)
make na              # NA variant: CAD, checks, renders
make eu              # EU variant: CAD, checks, renders
make print           # ElegooSlicer projects in print/
make renders         # docs/renders/*.png
make order           # DigiKey / Mouser lists, PCBWay packs

Status

• Ready to order: the NA and EU mains boards and both pin boards have PCBWay packs, after the human review in pcb/na/fab/README.md and pcb/eu/fab/README.md.
• Not ready to order: the NA and EU sensor boards (CN2's position on the MSR-2 is a photo estimate) and the back cover flex (contact positions not yet measured on a remote).
• To measure: the MEASURE and ESTIMATE values in docs/MEASUREMENTS.md.
• Not started: the ESPHome configuration for the MSR-2 with the SHT40 and the microphone.

Open items

Suitable for a contribution:

• a back cover with a battery and a charger;
• a UK variant (86 mm plate, shallow back box);
• a version for the BILRESA dual-button remote (IKEA E2489);
• a jumbo-plate option.

AGENTS.md has the conventions, the hard constraints and the checks that must stay green.

Cost (2026-10-12)

Parts and PCBs per plate, USD.

Sources and assumptions:

• Parts at 1, 5 and 100 (sourced): DigiKey US list prices for the order lists' parts (pcb/order/), cheapest packaging and price break for the total need, read 2026-10-12. Per plate:
  • 1 plate: NA full 50.97, NA battery-free 33.71, NA switch only 15.68; EU full 42.17, EU battery-free 25.83, EU switch only 10.59.
  • 5 plates: NA full 47.70, NA battery-free 31.63, NA switch only 14.96; EU full 36.86, EU battery-free 22.26, EU switch only 8.18.
  • 100 plates: NA full 34.20, NA battery-free 22.64, NA switch only 9.36; EU full 27.60, EU battery-free 16.92, EU switch only 6.00.
• Parts at 1,000 and 10,000 (assumption): 10 % and 15 % below the 100-plate price. DigiKey shows no prices above about 100 without a quote.
• PCBs at 1 and 5 (sourced): PCBWay's 5-piece minimum order, 2026-10-12; one plate pays for the whole order.
  • Mains board, pin board, EU mains board, EU pin board: 5.00 each order.
  • Sensor board 24.93, EU sensor board 25.44.
  • Cover flex: about 25 (estimate).
  • Per plate: 1 plate NA full 59.93, NA battery-free 35.00, EU full 60.44, EU battery-free 35.00, switch only 5.00 (the mains board alone); 5 plates one fifth of that.
• PCBs at 100 (sourced): PCBWay quotes for 100 pieces, 2026-10-12.
  • Mains board 0.64, sensor board 1.17, pin board 0.36.
  • EU mains board 0.64, EU pin board 0.45, EU sensor board 1.21.
  • Cover flex 1.24.
  • Per plate: NA full 3.41, NA battery-free 2.23, EU full 3.53, EU battery-free 2.32, switch only 0.64.
• PCBs at 1,000 and 10,000 (assumption): the 100-piece price (no quote). This is cautious: board prices usually fall at volume.
• MSR-2 (assumption): Apollo's retail price at every quantity, 37.99 base and 57.99 with CO2. No volume price is published.

Known gaps:

• Quote specs differ from the design:
  • The mains boards were quoted with 1 oz copper; the NA board is 2 oz. The copper bars are not quoted.
  • The pin board was quoted at 1.6 mm, not 0.8.
• Not included:
  • PCB assembly (the sensor board, the EU sensor board and the cover flex need it);
  • the IKEA remote;
  • printed parts, screws and heatshrink;
  • shipping and duties.
• Cheaper terminal blocks: Same Sky TBL-0021-500-06GR (NA) and TBL-0020-500-02GR (EU), push-in without a lever, fit the WAGO 2604 footprint and cost about 5–6 (NA) and 3 (EU) less per plate at 100. Not in the design.

Printed parts (own printer, 2026-10-13)

The barrier (one per variant, printed with the blank board for switch only, D-127) is printed in Elegoo PC-FR; the face plate, the EU carrier and the back cover in Elegoo PETG. Grams and times come from the slicer projects (make print). USD per plate.

Sources and assumptions:

• Filament (sourced): Elegoo US store, 10 kg packs, read 2026-10-12.
  • PC-FR: 229.99, 23.00 / kg (1 kg spool 34.99).
  • PETG Pro: 109.99, 11.00 / kg (1 kg spool 13.99).
• PETG weights (assumption): the face plates and carriers are sliced in PLA only. Their weight is scaled by the density ratio (PETG 1.27 / PLA 1.24) at the same print time.
• Electricity (assumption): 150 W average at 0.15 / kWh.
• Printer wear (assumption): about 440 for the CC2 Combo (Elegoo's bundles list at 435–499) over 5,000 print hours.
• Not included: labour, failed prints, bed adhesive.
• Print services: not quoted.