2 layers60 × 30 mm
Controller
google/mozc-devices
Circuit diagrams and firmware source code for Gboard DIY keyboards
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2 layers19.5 × 30 mm
TrafficLights
Ch3ema/Tracffic-LightsArduino traffic light simulator, breadboard prototype to custom KiCad PCB
- Size
- 19.5 × 30 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 11
- Nets
- 7
- Pads
- 20
- Tracks, vias
- 21, 0
- Routed
- Yes
- KiCad
- KiCad 10.0 (file 20260206)
- Created
- 10 Sep 2026
- Updated
- 10 Sep 2026
Overview
TrafficLights is an open-source printed circuit board by Ch3ema, from the Ch3ema/Tracffic-Lights repository on GitHub. It is a 2-layer board of 19.5 × 30 mm with 11 parts on 7 nets, routed with 21 tracks and 0 vias.
Its parts include 3 resistors, 3 diodes and 1 connector.
README
README.mdTraffic Light Simulator
An Arduino-controlled traffic light, built on a breadboard and then turned into a custom PCB in KiCad.
What it does
Three LEDs cycle through a standard traffic light sequence.
| Light | Arduino Pin | Duration |
|---|---|---|
| Green | D4 | 3 s |
| Yellow | D3 | 1 s |
| Red | D2 | 3 s |
Hardware
- Arduino Uno R3
- 3x 5 mm THT LEDs (red, yellow, green)
- 3x 220 Ω current-limiting resistors
- 1x 4-pin male header (GND + 3 signals)
Each LED anode connects to its Arduino pin through a 220 Ω resistor; all cathodes share a common ground. That gives roughly 14 mA per LED, well under the Uno's 20 mA per-pin limit.
PCB
Designed in KiCad 10. LEDs grouped at the top, resistors in a row below, 4-pin header at the bottom edge, and four M3 mounting holes at the corners.
Footprints:
- LEDs:
LED_THT:LED_D5.0mm - Resistors:
Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P5.08mm_Horizontal - Header:
Connector_PinHeader_2.54mm:PinHeader_1x04_P2.54mm_Vertical
Running it
- Flash
TrafficLights.inoto an Arduino Uno - Connect the header to the Uno: GND to GND, signals to D2, D3, D4
- Power over USB
Gerbers are in /kicad if you want to fabricate the board.
Possible improvements
- Pedestrian crossing button with interrupt-driven state change
- Replace blocking
delay()calls withmillis()timing so the board can respond to input mid-cycle - Second light head to simulate a full intersection
Parts
11| Qty | Value | Footprint | References |
|---|---|---|---|
| 4 | MountingHole | MountingHole:MountingHole_2.5mm_Pad | H1, H2, H3, H4 |
| 3 | 220 | Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P5.08mm_Horizontal | R1, R2, R3 |
| 3 | LED | LED_THT:LED_D3.0mm | D1, D2, D3 |
| 1 | Conn_01x04_Pin | Connector_PinHeader_2.54mm:PinHeader_1x04_P2.54mm_Horizontal | J1 |
Questions
How big is the TrafficLights PCB?
It measures 19.5 × 30 mm and has 2 copper layers, 1.6 mm thick.
What parts does the TrafficLights use?
11 parts. 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 TrafficLights KiCad files?
From the Ch3ema/Tracffic-Lights repository on GitHub, at the commit this page was made from: the board is KiCad/TrafficLights.kicad_pcb and its schematic KiCad/TrafficLights.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the TrafficLights design in my own project?
Its repository states no licence, so its author keeps all rights: ask Ch3ema before reusing the design.
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