2 layers83.3 × 65.3 mm
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46 parts14kMIT
2 layers90 × 48 mm
Intercom carrier
haarts/intercomA serverless home intercom system based on an ESP32 P4
- Size
- 90 × 48 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 38
- Nets
- 49
- Pads
- 122
- Tracks, vias
- 88, 1
- Pours
- 2
- Routed
- Yes
- KiCad
- KiCad 10.0 (file 20260206)
- Created
- 3 Oct 2026
- Updated
- 26 Oct 2026
Overview
Intercom carrier is an open-source printed circuit board by haarts, from the haarts/intercom repository on GitHub. It is a 2-layer board of 90 × 48 mm with 38 parts on 49 nets, routed with 88 tracks and 1 via.
It is built around the BC547. Its parts include 16 resistors, 8 connectors, 6 capacitors and 4 transistors.
Main components
1README
README.mdIntercom boerderij
A home intercom built from Waveshare ESP32-P4-WIFI6-POE-ETH wall boxes. There are two routes:
- Mumble: the boxes run a Mumble client. There is one Mumble server for the house, Mumble channels route audio to rooms, and Home Assistant is integrated.
- lanicom (
lanicom/): serverless. Boxes find each other on the LAN and talk directly, with encrypted unicast. No Mumble server, and Home Assistant is optional (it can join as a peer), so friends can build it too. See lanicom/README.md and the plan with its design review in lanicom/PLAN.md.
| Path | What |
|---|---|
lanicom/ | Serverless intercom: protocol spec, C core, ESPHome component, Python CLI, HA integration |
esp32-mumble/ | dchote/esp32-mumble (git subtree) with ESP32-P4 support and audio fixes. Board config: esp32-mumble/esphome/waveshare-esp32-p4-poe.yaml |
esphome/p4-bringup.yaml | Minimal bring-up config for the board (Ethernet, codec, mic level) |
server/mumble/ | Docker Compose file for the Mumble server (Murmur) |
tools/voicetest/ | End-to-end voice test: play speech near the board, record it from Mumble, score it with Whisper |
PROJECT_NOTES.md | Decisions, measurements and open items |
Build and flash
python3 -m venv .venv && .venv/bin/pip install esphome==2026.7.1
cd esp32-mumble/esphome
../../.venv/bin/esphome run waveshare-esp32-p4-poe.yaml # first flash over USB-C, later OTAThe Mumble server address is filled in automatically with Home Assistant's IP when the device is adopted, or set it under the device's "1. Server" setting.
Voice test
tools/voicetest/run.sh local ptt tools/voicetest/berend-nl-pad.wav nlPlays the clip on this machine's default audio output, records what the board sends
to the Mumble server, and prints Whisper's transcript and word error rate. See the
comments in run.sh for the options.
Parts
38| Qty | Value | Footprint | References |
|---|---|---|---|
| 8 | 1k | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal | R1, R2, R3, R4, R5, R6, R7, R8 |
| 5 | 100nF | Capacitor_THT:C_Disc_D3.0mm_W1.6mm_P2.50mm | C1, C2, C3, C4, C6 |
| 4 | 0R | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal | R13, R14, R15, R16 |
| 4 | 10k | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal | R9, R10, R11, R12 |
| 4 | BC547 | Package_TO_SOT_THT:TO-92_Inline | Q1, Q2, Q3, Q4 |
| 4 | MountingHole_3.2mm_M3 | MountingHole:MountingHole_3.2mm_M3 | H1, H2, H3, H4 |
| 1 | 10uF | Capacitor_THT:CP_Radial_D5.0mm_P2.00mm | C5 |
| 1 | Button 1 (JST-XH) | Connector_JST:JST_XH_B4B-XH-A_1x04_P2.50mm_Vertical | J2 |
| 1 | Button 2 (JST-XH) | Connector_JST:JST_XH_B4B-XH-A_1x04_P2.50mm_Vertical | J3 |
| 1 | Button 3 (JST-XH) | Connector_JST:JST_XH_B4B-XH-A_1x04_P2.50mm_Vertical | J4 |
| 1 | Button 4 (JST-XH) | Connector_JST:JST_XH_B4B-XH-A_1x04_P2.50mm_Vertical | J5 |
| 1 | Off switch (JST-XH) | Connector_JST:JST_XH_B2B-XH-A_1x02_P2.50mm_Vertical | J8 |
| 1 | P4 pins 1-20 | Connector_PinSocket_2.54mm:PinSocket_1x20_P2.54mm_Vertical | J1 |
| 1 | P4 pins 21-40 | Connector_PinSocket_2.54mm:PinSocket_1x20_P2.54mm_Vertical | J7 |
| 1 | Spare GPIO2/3 | Connector_PinHeader_2.54mm:PinHeader_1x04_P2.54mm_Vertical | J6 |
Questions
How big is the Intercom carrier PCB?
It measures 90 × 48 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Intercom carrier use?
38 parts, built around the BC547. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the Intercom carrier KiCad files?
From the haarts/intercom repository on GitHub, at the commit this page was made from: the board is hardware/carrier/intercom-carrier.kicad_pcb and its schematic hardware/carrier/intercom-carrier.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Intercom carrier design in my own project?
Its repository states no licence, so its author keeps all rights: ask haarts before reusing the design.
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