2 layers80 × 125.3 mm
Phone robot
HeyPCB/phone-robot
Bolt, the phone stand robot: A little robot that holds your phone, charges it, and peeks over the top to tell you how it's eating. KiCad 10, heypcb.ai merch.
35 partsCERN-OHL-S-2.0
2 layers50.6 × 62.2 mm
Air ghost
HeyPCB/air-ghostAir Ghost: A little ghost that blushes red when your room needs fresh air. KiCad 10, heypcb.ai merch.
- Size
- 50.6 × 62.2 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 19
- Nets
- 28
- Pads
- 102
- Tracks, vias
- 176, 10
- Pours
- 7
- Routed
- Yes
- KiCad
- KiCad 10.0 (file 20260206)
- Created
- 5 Oct 2026
- Updated
- 5 Oct 2026
Overview
Air ghost is an open-source printed circuit board by HeyPCB, from the HeyPCB/air-ghost repository on GitHub, published under the CERN-OHL-S-2.0 licence. It is a 2-layer board of 50.6 × 62.2 mm with 19 parts on 28 nets, routed with 176 tracks and 10 vias.
It is built around the CH32V003F4P6, SCD40-D-R2 and CC0603KRX7R9BB104, with the CL21A106KAYNNNE, WS2812C-2020-V1 and TS-1187A-B-A-B among its other parts. Its parts include 6 capacitors, 4 resistors, 2 ICs, 2 diodes and 1 connector. It belongs with the sensors and measurement boards and the RISC-V boards of this library.
Main components
7
CH32V003F4P6
TSSOP-20-175milTSSOP-20-175mil Microcontrollers (MCU/MPU/SOC) ROHSWCH (Nanjing Qinheng Microelectronics)Microcontrollers (MCU/MPU/SOC)
SCD40-D-R2
LGA-20(10.1x10.1)-10℃~+60℃ 10.1mm 10.1mm 15mA 2.4V~5.5V 400ppm~2000ppm 6.5mm Air quality I2C Reset function ±5% LGA-20(10.1x10.1) Gas Sensors ROHSSensirionGas Sensors
CC0603KRX7R9BB104
0603100nF 50V X7R ±10% 0603 Multilayer Ceramic Capacitors MLCC - SMD/SMT ROHSYAGEOMultilayer Ceramic Capacitors MLCC - SMD/SMT
CL21A106KAYNNNE
080510uF 25V X5R ±10% 0805 Multilayer Ceramic Capacitors MLCC - SMD/SMT ROHSSamsung Electro-MechanicsMultilayer Ceramic Capacitors MLCC - SMD/SMT
WS2812C-2020-V1
SMD,2x2mm0.5mA 0.84mm 2.2mm 2kHz 2mm 3.7V~5.3V 800Kbit/s Built-in power-on reset circuit、Built-in power-on reset circuit G:520nm、R:624nm、B:467nm R:130mcd、G:320mcd、B:60mcd SMD,2x2mm RGB LEDs(Built-in IC) ROHSWorldsemiRGB LEDs(Built-In IC)
TS-1187A-B-A-B
SMD-4P,5.1x5.1mm-30℃~+85℃ 1.5mm 1.6N 100,000 cycles 12V 5.1mm 5.1mm 50mA Gold No Round Button SPST Surface Mount,Vertical Without Bracket SMD-4P,5.1x5.1mm Tactile Switches ROHSXKB ConnectionTactile Switches
TYPE-C-31-M-12
SMD-30℃~+80℃ 1 10,000 cycles 16P 20V 5A 7.35mm Female Surface Mount, Right Angle Type-C SMD USB Connectors ROHSHRO ElectronicsUSB Connectors
README
README.mdAir Ghost
A little ghost that blushes red when your room needs fresh air.
Air Ghost is a desk CO2 monitor shaped like a ghost, on USB-C. A Sensirion SCD40 measures real CO2 (photoacoustic NDIR, not a VOC estimate) plus temperature and humidity every 5 s, and a CH32V003 turns the reading into the colour of the ghost's two WS2812 cheeks: green when the air is fresh, through yellow and orange to a pulsing red at 2000 ppm. Its round "O" mouth is a button: boop it for temperature and humidity colours, hold it for night mode.
| Layers | Size | Parts | Nets | Connections routed | Vias | ERC errors | DRC errors / unconnected / parity | BOM @100 |
|---|---|---|---|---|---|---|---|---|
| 2 | 50.7 x 62.3 mm | 16 (+3 pads) | 12 | 50 -> 0 open | 10 | 0 | 0 / 0 / 0 | $15.66 |
Not fabricated, assembled or powered yet. Every number on this page is measured by KiCad 10.0.6 on
the files in this repository (report.json, measured.json) or read
from the live JLC/LCSC catalogue (bom_cost.json).
| Spec, power budget, BOM | SPEC.md |
| Store copy | STORE_COPY.md |
| KiCad 10 project | kicad/ |
| Gerbers, drill, BOM, CPL, STEP, schematic PDF | fab/ |
| Firmware | firmware/ |
| Renders | front, back, hero, Circuit World thumbnail |
| Brief and generator | design/ |
What's on it
- Sensor: Sensirion SCD40-D-R2 (CO2 400-2000 ppm, temperature, humidity) at I2C 0x62, from 5 V, with 10 uF + 100 nF beside it and 10k pull-ups.
- MCU: CH32V003F4P6 from 5 V; bit-banged I2C with CRC checks (ch32fun's static_i2c.h).
- Cheeks: two WS2812C-2020 RGB LEDs, each with its 100 nF, chained from PC6.
- Mouth: a TS-1187A button; its round plunger is the ghost's "O".
- Power: USB-C with 5.1 kOhm CC pull-downs, about 25 mA (SPEC.md).
- BOM: $15.66 at 100, of which the SCD40 is $14.82: the collection's one deliberate exception to its $8 target (SPEC.md says why).
Finish
White solder mask, Black silkscreen, ENIG copper finish, 1.6 mm FR4, top-side SMT assembly (J1: an SMD part whose shell legs go through plated holes, soldered on the same SMT line). The gold art is bare copper under a mask opening (ENIG), drawn with its own keep-out so no track runs under it. The QR code on the back opens https://heypcb.ai/world/b/0fc87b5d15f5.
How it was made
Designed with the HeyPCB method on KiCad 10.0.6, headless, by the heypcb-kicad pipeline: a written
brief composed from reusable circuit blocks, every pin from KiCad's own symbol library, every part bound
to an LCSC number from a dated catalogue read, then ERC, a netlist round trip, locked placement,
Freerouting 2.4.1, pours, silkscreen and board art, DRC with schematic parity, DFM and a fab gate,
each stage gated by a measurement. design/make_brief.py regenerates the brief (outline, part
locks and art) from code.
Part of the heypcb.ai merch collection.
License
Hardware: CERN-OHL-S v2. Firmware: MIT (see firmware/LICENSE). KiCad's symbol, footprint and 3D
libraries used in the design are CC-BY-SA 4.0 with the KiCad library exception.
Parts
19| Qty | Value | Footprint | References |
|---|---|---|---|
| 2 | 100nF | Capacitor_SMD:C_0603_1608Metric | C2, C4 |
| 2 | 100nF | Capacitor_SMD:C_0402_1005Metric | C5, C6 |
| 2 | 10k | Resistor_SMD:R_0402_1005Metric | R3, R4 |
| 2 | 10uF | Capacitor_SMD:C_0805_2012Metric | C1, C3 |
| 2 | 5.1k | Resistor_SMD:R_0402_1005Metric | R1, R2 |
| 2 | WS2812C-2020-V1 | LED_SMD:LED_WS2812B-2020_PLCC4_2.0x2.0mm | D1, D2 |
| 1 | CH32V003F4P6 | Package_SO:TSSOP-20_4.4x6.5mm_P0.65mm | U1 |
| 1 | GND | TestPoint:TestPoint_Pad_1.0x1.0mm | TP3 |
| 1 | SCD40-D-R2 | Sensor:Sensirion_SCD4x-1EP_10.1x10.1mm_P1.25mm_EP4.8x4.8mm | U2 |
| 1 | SWIO | TestPoint:TestPoint_Pad_1.0x1.0mm | TP2 |
| 1 | TS-1187A | Button_Switch_SMD:SW_Push_1P1T_XKB_TS-1187A | SW1 |
| 1 | USB-C | Connector_USB:USB_C_Receptacle_HRO_TYPE-C-31-M-12 | J1 |
| 1 | VDD | TestPoint:TestPoint_Pad_1.0x1.0mm | TP1 |
Questions
How big is the Air ghost PCB?
It measures 50.6 × 62.2 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Air ghost use?
19 parts, built around the CH32V003F4P6, SCD40-D-R2, CC0603KRX7R9BB104 and CL21A106KAYNNNE. 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 Air ghost KiCad files?
From the HeyPCB/air-ghost repository on GitHub, at the commit this page was made from: the board is kicad/air_ghost.kicad_pcb and its schematic kicad/air_ghost.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Air ghost design in my own project?
Its repository publishes it under the CERN-OHL-S-2.0 licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).
Similar boards
- 6 layers72.4 × 115 mm
FujiNet-7800-Rev0
FujiNetWIFI/fujinet-hardware
Schematics and design files for FujiNet hardware
135 parts142 - 2 layers53.9 × 62.6 mm
Moon light
HeyPCB/moon-light
Luna, the night-light moon: A sleepy moon that turns on at dusk and tucks itself in after you fall asleep. KiCad 10, heypcb.ai merch.
36 parts1CERN-OHL-S-2.0 - 2 layers69.6 × 66.4 mm
Pomodoro pal
HeyPCB/pomodoro-pal
Pomodoro Pal: A tomato on your desk that keeps you focused for 25 minutes, without your phone. KiCad 10, heypcb.ai merch.
41 partsCERN-OHL-S-2.0 - 4 layers85.1 × 87.7 mm
Art big paw
HeyPCB/led-art
Shaped LED boards inspired by films, each in its own colour: KiCad 10, JLCPCB-ready, CERN-OHL-S-2.0
48 partsCERN-OHL-S-2.0 - 4 layers55.6 × 101.5 mm
Art melody
HeyPCB/led-art-2
More shaped LED boards inspired by films, each in its own colour: KiCad 10, JLCPCB-ready, CERN-OHL-S-2.0
26 partsCERN-OHL-S-2.0 - 4 layers100 × 75 mm
Freedo radio
CappyT/freedo
Local coordinator for tado V3+ heating devices, with a Home Assistant integration and add-on
135 parts33Apache-2.0 - 4 layers65 × 45 mm
Lora gps tracker rev a
bogdan-kovalchuk/esp32-lora-gps-tracker
Encrypted point-to-point GPS telemetry over 433 MHz LoRa between two ESP32 boards.
69 partsMIT