2 layers
2 layers91.9 × 77.8 mm
Keychain
adonutartist/Nemo-PCB-Keychain1as the title says its a pcb and a keychain
- Size
- 91.9 × 77.8 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 11
- Nets
- 5
- Pads
- 13
- Tracks, vias
- 21, 1
- Pours
- 2
- Routed
- Yes
- KiCad
- KiCad 10.0 (file 20260206)
- Created
- 20 Aug 2026
- Updated
- 23 Aug 2026
Overview
Keychain is an open-source printed circuit board by adonutartist, from the adonutartist/Nemo-PCB-Keychain repository on GitHub. It is a 2-layer board of 91.9 × 77.8 mm with 11 parts on 5 nets, routed with 21 tracks and 1 via.
It is built around the TTP223-BA6 and CR2032. Its parts include 1 resistor, 1 IC and 1 diode.
Main components
2README
README.mdTotal Time Spent: 4h 01m
Nemo's PCB Keychain
This is a smol interactive PCB keychain that looks super cute :3 Made for Hackclub Gadget Market.
How It Works
The keychain uses a TTP223 capacitive touch sensor to detect when someone touches the copper artwork on the front of the PCB which ativates the LED.
The basic flow is:
Finger Touches Golden Part of PCB (f.Cu Layer Art) --> TTP223 Capacitive Touch Sensor --> Q Output --> 1kΩ Resistor --> LED lights up
The board is powered by a CR2032 coin cell battery. The copper artwork on the front doubles as the touch electrode so no extra buttons are required. The LED is mounted on the back of the PCB and faces toward the FR-4 nose. When the artwork is touched, the LED illuminates the PCB from behind, producing a glow diffused well by the FR4 Layer.
Project Journal
The development process, experiments, decisions, and progress are documented in the project journal.
Read the development journal -->
Schematic
The schematic:
PCB Layout
The PCB layout:
3D Render
A 3D render of the finished PCB:
Bill of Materials
| Component | Quantity | Description | Est. Cost |
|---|---|---|---|
| TTP223-BA6 | 1 | Capacitive touch sensor | ₹10 / $0.10 |
| CR2032 | 1 | 3V coin-cell battery | ₹219 / $2.29 |
| CR2032 Holder | 1 | PCB-mounted coin-cell holder | ₹53 / $0.55 |
| LED | 1 | 0603 SMD LED | ₹1.38 / $0.01 |
| Resistor | 1 | 1kΩ 0603 SMD resistor | ₹0.34 / $0.0001 |
| PCB | 5 | Custom 2-layer PCB | ₹900 / $9.40 |
| Total | ₹1,183.72 / $12.36 |
| TTP223-BA6 | CR2032 | CR2032 Holder |
|---|---|---|
| 0603 LED | 1kΩ Resistor | Custom PCB |
|---|---|---|
Features
- Custom copper artwork doubles as the touch sensor
- Custom silkscreen art
- FR4 Nose for good light diffusion
- Capacitive touch activation
- Hidden reverse-mounted LED
- CR2032 battery powered
- Compact keychain sized PCB
- No microcontroller required
- Custom PCB artwork
Parts
11| Qty | Value | Footprint | References |
|---|---|---|---|
| 6 | LOGO | LOGO | G***, G***, G***, G***, G***, G*** |
| 1 | 1kΩ | Resistor_SMD:R_0603_1608Metric | R1 |
| 1 | CR2032 | Battery:BatteryHolder_Keystone_1060_1x2032 | BT1 |
| 1 | LED | LED_SMD:LED_0603_1608Metric | D1 |
| 1 | TTP223-BA6 | keychain:SOT23-6 | U1 |
The 10 most common of 11 parts.
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Questions
How big is the Keychain PCB?
It measures 91.9 × 77.8 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Keychain use?
11 parts, built around the TTP223-BA6 and CR2032. 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 Keychain KiCad files?
From the adonutartist/Nemo-PCB-Keychain repository on GitHub, at the commit this page was made from: the board is keychain/keychain.kicad_pcb and its schematic keychain/keychain.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Keychain design in my own project?
Its repository states no licence, so its author keeps all rights: ask adonutartist before reusing the design.