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.
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.
Original reference: hackaday.com →