2 layers21.5 × 14.1 mm Bessel filter, the printed circuit board in 3D

Bessel filter

Size: 21.5 × 14.1 mm
Copper layers: 2
Thickness: 1.6 mm
Parts: 23
Nets: 13
Pads: 63
Tracks, vias: 128, 24
Pours: 1
Routed: Yes
KiCad: KiCad 9.0 (file 20241229)
Created: 2 Apr 2026
Updated: 2 Apr 2026

Overview

Bessel filter is an open-source printed circuit board by Pgr18, from the Pgr18/testtt repository on GitHub. It is a 2-layer board of 21.5 × 14.1 mm with 23 parts on 13 nets, routed with 128 tracks and 24 vias.

It is built around the RS721SXH. Its parts include 12 capacitors and 7 resistors.

Main components

RS721SXH
SOT-23-6-2.75V~-1.25V、1.25V~2.75V -40℃~+125℃ 1 1.15mA 10MHz 10pA 1pA 2.5V~5.5V 2.6uV/℃ 500uV 70mA 7V 7V/us 85dB 9.5nV/√Hz@1kHz Enable/shutdown function Rail-to-Rail Input, Rail-to-Rail Output SOT-23-6 Operational Amplifier ROHSJiangsu RUNIC TechOperational Amplifier

README

README.md

testtt

Parts

Qty	Value	Footprint	References
7	20к	EDA_lib:RES_0603	R1, R2, R3, R4, R5, R6, R7
6	0,1мк	EDA_lib:CAP_0603	C3, C4, C7, C8, C11, C12
6	10мк	EDA_lib:CAP_0603	C1, C2, C5, C6, C9, C10
3	RS721S	EDA_lib:SOT23-6	DA1, DA2, DA3
1	PLS-7	Connector_PinHeader_2.54mm:PinHeader_1x07_P2.54mm_Vertical	XP1

Questions

How big is the Bessel filter PCB?

It measures 21.5 × 14.1 mm and has 2 copper layers, 1.6 mm thick.

What parts does the Bessel filter use?

23 parts, built around the RS721SXH. 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 Bessel filter KiCad files?

From the Pgr18/testtt repository on GitHub, at the commit this page was made from: the board is bessel_filter.kicad_pcb and its schematic bessel_filter.kicad_sch. PCBKit opens the board in the browser, with nothing to install.

Can I use the Bessel filter design in my own project?

Its repository states no licence, so its author keeps all rights: ask Pgr18 before reusing the design.

Project files

Show this board on your page

A live frame, for any web page

<iframe src="https://pcbkit.io/embed/boards/pgr18-testtt" title="Bessel filter in PCBKit" width="100%" height="480" style="border:0;border-radius:12px" allow="fullscreen" loading="lazy"></iframe>

A picture

<img src="https://pcbkit.io/embed/boards/pgr18-testtt.jpg" alt="Bessel filter" width="1200" height="900">

A picture that opens the board, for a README

[![Bessel filter](https://pcbkit.io/embed/boards/pgr18-testtt.jpg?size=s)](https://pcbkit.io/boards/pgr18-testtt)

Source

Repository: Pgr18/testtt
Board file: bessel_filter.kicad_pcb
Commit: 0dbed2a
Licence: Not stated

Similar boards

2 layers65 × 56 mm
Pi servo hat
earthtojake/text-to-cad
Design physical products with AI
23 parts26kMIT
2 layers14 × 100 mm
Yunomi
google/mozc-devices
Circuit diagrams and firmware source code for Gboard DIY keyboards
23 parts3kApache-2.0
2 layers50.8 × 52.2 mm
Fuhhni
hackclub/OnBoard
💡 Join 1,000 teenagers and make your first PCB with a $100 grant!
23 parts915
2 layers138.8 × 89.8 mm
Keyboard pcb
diepala/cantor
Cantor keyboard, a 42 key diodeless split keyboard.
23 parts756GPL-3.0
2 layers32.9 × 53.3 mm
Goatgdo
Kaldek/rat-ratgdo
Open source schematics for ratgdo PCB
23 parts511MIT
2 layers35.5 × 50 mm
Tobo
kelu124/echomods
Open source ultrasound processing modules and building blocks
23 parts463
2 layers19 × 19 mm
Keybit
notaroomba/keybytes
A truly modular keyboard
23 parts444
2 layers88.5 × 28 mm
ExpBreakout
Duet3D/Duet-2-Hardware
The KiCAD source for the Duet 3d printer controller see www.duet3d.com
23 parts258