# Open-source linear capacitive encoder hits 40-micrometer accuracy

> **Key takeaway:** Nick has published an open-source linear capacitive encoder design achieving 40-micrometer accuracy using PCB-etched antennas and an STM32 microcontroller.

**Published:** 2026-10-22T20:00:48+00:00 
**Source:** Hackaday Hardware 
**Category:** open-hardware 
**Canonical URL:** https://fosswire.org/news/open-source-linear-capacitive-encoder-hits-40-micrometer-acc.html 

## Summary
A maker known as Nick has released an open-source linear capacitive encoder built from standard PCB fabrication. The design uses eight transmitting antennas on a moving sensor PCB and a fixed reflector PCB; an STM32 reads the varying capacitance to determine position. The system achieves 40-micrometer accuracy. Design files and documentation are available on GitHub.

## How the capacitive encoder works
- **Sensor PCB**: grid of eight transmitting antennas etched into the PCB, plus a larger receiving antenna
- **Reflector PCB**: fixed in place; its elements bounce signals back to the sensor
- **Principle**: as the sensor moves, relative position of reflector elements changes capacitive coupling, varying pulse strength at the receiver
- **Microcontroller**: STM32 reads pulses and computes displacement
- **Accuracy**: 40 micrometers
- **Availability**: PCB files and explanatory documentation on GitHub

## Why it matters
The project offers a reproducible, low-cost alternative to commercial linear encoders for precision positioning in DIY CNC, robotics, and metrology equipment.