3 open source boards using the 4N25
Real designs built with the 4N25, from public GitHub projects: a quick way to see how others power, decouple and connect it. Each board comes with its KiCad files, full parts list and a render — and you can simulate its firmware on HardLabs.
Kicad project
Invisible-Luna
63.6 × 63.6 mm25 parts2LNo license1
ESP32Smart-Home-Controller
Ajith-Anand-R
100 × 80 mm11 parts2LMIT1
LTC3 Charge Controller
psas
103.5 × 85 mm110 parts4LNo license19
The 4N25 in open source designs
The gallery holds 3 open source boards using the 4N25 from 3 GitHub repositories; a typical one measures about 100 × 80 mm and carries around 25 components.
67% are two-layer designs, the rest use four layers or more, and 33% carry an open source license.
The most starred is LTC3 Charge Controller by psas.
Microcontrollers on boards using the 4N25
What boards using the 4N25 are built for
4N25: common questions
Where can I find a 4N25 reference design?
Each of the 3 boards on this page is a real design using the 4N25. Open one to see how it is wired up, with the full BOM, a render of the layout and links to its KiCad files.
Which microcontrollers do boards using the 4N25 use?
Most are built on ESP32 (1).
How big is a typical board using the 4N25?
The median is 100 × 80 mm, and 67% are two-layer designs.
What is the most popular open source board using the 4N25?
By GitHub stars, LTC3 Charge Controller by psas, with 19 stars.
Can I simulate one of these boards using the 4N25 before building it?
Yes. HardLabs turns a board's netlist and BOM into a working simulation, so you can boot and test firmware against it with no hardware on your desk.