2 layers304.8 × 170.8 mm
2 layers40 × 82 mm
Gemini BC
Spr1ngLif3/Gemini_BC1A simple and affordable board computer for bistage rockets
- Size
- 40 × 82 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 12
- Nets
- 41
- Pads
- 128
- Tracks, vias
- 76, 12
- Pours
- 1
- Routed
- Yes
- KiCad
- KiCad 10.0 (file 20260206)
- Created
- 16 Jun 2026
- Updated
- 16 Jun 2026
Overview
Gemini BC is an open-source printed circuit board by Spr1ngLif3, from the Spr1ngLif3/Gemini_BC repository on GitHub. It is a 2-layer board of 40 × 82 mm with 12 parts on 41 nets, routed with 76 tracks and 12 vias.
It is built around the IRLZ44N. Its parts include 5 connectors, 1 transistor and 1 switch. It belongs with the RP2040 boards of this library.
Main components
1README
README.md[blocked]
Gemini Board Computer
A simple and affordable board computer for bistage rockets!
Scripts
·
Gerbers
·
Request Feature
Table of Contents
About The Project
Building avionics for rockets can be really difficult: you have to choose the microcontroller, the sensors and how to use it for implement all the feature you want.
The experience looks overwhelming.
This is the right project for you! I developed a first simple platform to implement a complete bistage rocket avionic. This board contains the essential parts for satisfy only two tasks:
- Starting the second stage of a rocket.
- Log all the data from the launch in a microSD card.
I used a cheap and modular microcontroller (the Raspberry Pi Pico) for control all the components and I programmed it with the easiest programming language in the world: Python.
Getting Started
Hardware
The board is designed with KiCAD software, an open source for making schematics and PCBs.
For editing and take a look to the project, you can open KiCAD and select the option Open Project (CTRL + O) in the top-left menu.
After that, select the .kicd_pro file in the hardware folder.
If you want to send in production the board (with serivces like JLCPCB or PCBWay etc.) you can zip the gerbers folder and upload the zip file to the production service site. I can also modify the PCB and regenerate the gerbers via KiCAD and make your own board.
Note!!!
The KiCAD project needs the TP4056 battery manager footprint to work. You can find it in the utils folder. For help KiCAD recognize it, move the .kicad_mod file in the same folder of the project file. If you notice some problems, please open a issue or contact me.
Software
- Install VSCode and setup the environment for the Raspberry Pi Pico. Check this tutorial (not related to me).
- Clone the repo.
sh git clone https://github.com/Spr1ngLif3/Gemini_BC.git - Open the
softwarefolder in VSCode.sh code Gemini_BC/software - Now you can upload the basic script on the board with the command MicroPico: Upload current file to Pico.
Please do your checks before uploading the scripts and put the board inside a rocket! I'm not responsible for all missusage of this scripts.
- Board ready for launch.
Usage
For using it in the wild (in the rocket), be careful to the polarity of the connectors on the board. The battery has a specific polarity but not the igniter (it should not care). I tested the board with some solid rocket engines designed for small rocket models, and I adjusted the timer for the second stage ignition based on the simulation and the specs of the engine.
The board can also charge the battery itself via USB-C with the TP4056 module on board.
Before the launch, be sure that the microSD card is correctly inserted and formatted in the FAT32 filesystem, the battery led is solid blue and the board is well secured on the rocket body.
After that, when you pull the switch to on the Pico boot and start executing the script loaded in it.
Contributing
Contributions are what make the open source community such an amazing place to learn, inspire, and create. Any contributions you make are greatly appreciated.
If you have a suggestion that would make this better, please fork the repo and create a pull request. You can also simply open an issue. Don't forget to give the project a star! Thanks again!
- Fork the Project
- Create your Feature Branch (
git checkout -b feature/AmazingFeature) - Commit your Changes (
git commit -m 'Add some AmazingFeature') - Push to the Branch (
git push origin feature/AmazingFeature) - Open a Pull Request
License
Hardware files are licensed under CERN-OHL-S v2.
Software and scripts are licensed under GPLv3.
See LICENSE folder for more information.
Contact
Website: SpaceZero
Acknowledgments
I list here some resources that I feel useful for you:
Made with <3 by an hacker.
Parts
12| Qty | Value | Footprint | References |
|---|---|---|---|
| 4 | MountingHole_2.2mm_M2_DIN965_Pad_TopBottom | MountingHole:MountingHole_2.2mm_M2_DIN965_Pad_TopBottom | M2, M2, M2, M2 |
| 1 | BM180 | Connector_PinHeader_2.54mm:PinHeader_1x04_P2.54mm_Vertical | J1 |
| 1 | IRLZ44N | Package_TO_SOT_THT:TO-220-3_Vertical | Q1 |
| 1 | Lipo | Connector_JST:JST_PH_B2B-PH-K_1x02_P2.00mm_Vertical | J3 |
| 1 | MicroSD | Connector_PinHeader_2.54mm:PinHeader_1x06_P2.54mm_Vertical | J2 |
| 1 | Motor | Connector_JST:JST_PH_B2B-PH-K_1x02_P2.00mm_Vertical | J4 |
| 1 | RaspberryPi_Pico | Module:RaspberryPi_Pico_SMD_HandSolder | A1 |
| 1 | SWITCH | Connector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_Vertical | SW1 |
| 1 | TP4056_PB | Module:TP4056-18650 | J5 |
Questions
How big is the Gemini BC PCB?
It measures 40 × 82 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Gemini BC use?
12 parts, built around the IRLZ44N. 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 Gemini BC KiCad files?
From the Spr1ngLif3/Gemini_BC repository on GitHub, at the commit this page was made from: the board is hardware/Gemini_BC.kicad_pcb and its schematic hardware/Gemini_BC.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Gemini BC design in my own project?
Its repository states no licence, so its author keeps all rights: ask Spr1ngLif3 before reusing the design.
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