

Ioboard
Open hardware eurorack synth modules
- Size
- 39.4 × 107.9 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 66
- Nets
- 66
- Pads
- 196
- Tracks, vias
- 600, 50
- Pours
- 2
- Routed
- Yes
- KiCad
- KiCad 7 (file 20221018)
- Created
- 9 Sep 2022
- Updated
- 18 Dec 2024
Overview
Ioboard is an open-source printed circuit board by jypma, from the jypma/modsynth repository on GitHub. It is a 2-layer board of 39.4 × 107.9 mm with 66 parts on 66 nets, routed with 600 tracks and 50 vias.
It is built around the RB521S30 and 1N5817W. Its parts include 19 resistors, 17 connectors, 12 diodes, 4 capacitors and 3 switches. It belongs with the audio and music boards of this library.
Main components
2README
README.mdEurorack modules collection

This repository contains a collection of eurorack module open hardware designs. It is a combination of designs found elsewhere (with references where relevant), and designs by me.
All schematics and boards are in Kicad format, and schematics, board and gerber exports are automated using KiBot and docker (see export.sh).
Modules
The following modules are available:
- A AS3340-based oscillator designed by me (based on a combination of earlier designs from the internet)
- A PT2399-based delay designed by me (based on a combination of earlier designs from the internet)
- A Dual 4-channel mixer module designed by me (based on basic opamp mixer essentials)
- A Quad Attenuverter with offset, based on an internet design
- Ornament & Crime, a well-known open hardware design
- Ray Wilson's Dual-VCA as originally designed by Gerbrand Sterrenburg
- Roland System 100 ADSR as originally designed by Gerbrand Sterrenburg
- The YUSynth Steiner VCF as originally designed by Gerbrand Sterrenburg
- Music Thing Modular's Turing Machine, a well-known open hardware design
Utilities
- A 16-bin DIP to SOIC adapter board (to mount SOIC chips on DIP sockets)
- A Power distribution board for eurorack modules
Combined bill of material and shopping list
I'm maintaining a merged bill of material for all modules, with component lists in stock at time of writing.
The only exception is the Teensy 3.0 / 3.1 / 3.2 required for Ornament & Crime. Those are impossible to find at the moment (I happen to have some, hence it's on the list).
Generating BOM, gerbers, and pictures
The script export.sh in the root of the project will generate or update the artifacts in the export/ directory, such as BOMs, gerber files, packages, and various documentation pictures. Most of these files are not version-controlled (but those linked from the markdown documentation are).
Whenever changing a schematic, the export script will update the relevant pictures and artifacts. Re-exporting the same schematic will result in the same picture, so git plays nice with this.
Link for simulation of triangle to sine converter
Parts
66| Qty | Value | Footprint | References |
|---|---|---|---|
| 6 | SolderJumper_3_Bridged12 | Jumper:SolderJumper-3_P1.3mm_Bridged12_RoundedPad1.0x1.5mm_NumberLabels | JP1, JP2, JP3, JP4, JP5, JP6 |
| 5 | 3.9k | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R14, R16, R17, R18, R19 |
| 5 | LED_Dual_Bidirectional | LED_THT:LED_D3.0mm | D6, D9, D10, D11, D12 |
| 4 | 100n | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C1, C2, C3, C4 |
| 4 | 270k | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R3, R4, R5, R6 |
| 4 | RB521S30 | Diode_SMD:D_SOD-523 | D4, D5, D7, D8 |
| 3 | 100k | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R8, R10, R12 |
| 3 | 1N5817W | Diode_SMD:D_SOD-123 | D1, D2, D3 |
| 3 | 1k | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R7, R9, R11 |
| 2 | 100k | Potentiometer_THT:Potentiometer_Alps_RK09K_Single_Vertical | CV_ADJ1, CV_ADJ2 |
| 2 | 3.3k | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R13, R15 |
| 2 | 33k | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R1, R2 |
| 2 | RotaryEncoder_Switch | Rotary_Encoder:RotaryEncoder_Alps_EC12E-Switch_Vertical_H20mm | ENC1, ENC2 |
| 1 | CV1_IN | Library:Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHoles_Hole | J1 |
| 1 | CV2_IN | Library:Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHoles_Hole | J2 |
| 1 | Conn_02x03_Odd_Even | Connector_PinHeader_2.54mm:PinHeader_2x03_P2.54mm_Vertical | J6 |
| 1 | Conn_02x08_Odd_Even | Connector_PinHeader_2.54mm:PinHeader_2x08_P2.54mm_Vertical | J3 |
| 1 | Conn_MIDI | Connector_PinHeader_2.54mm:PinHeader_1x06_P2.54mm_Vertical | J5 |
| 1 | IN1 | Library:Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHoles_Hole | J9 |
| 1 | IN2 | Library:Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHoles_Hole | J10 |
| 1 | IN3 | Library:Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHoles_Hole | J11 |
| 1 | MIDI_IN | Library:Low-profile Minijack | J17 |
| 1 | MIDI_OUT | Library:Low-profile Minijack | J8 |
| 1 | MIDI_THRU | Library:Low-profile Minijack | J7 |
| 1 | MountingHole | MountingHole:MountingHole_3.2mm_M3_DIN965 | H1 |
| 1 | OUT1 | Library:Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHoles_Hole | J12 |
| 1 | OUT2 | Library:Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHoles_Hole | J13 |
| 1 | OUT3 | Library:Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHoles_Hole | J14 |
| 1 | OUTA | Library:Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHoles_Hole | J15 |
| 1 | OUTB | Library:Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHoles_Hole | J16 |
| 1 | SCREEN | Connector_PinSocket_2.54mm:PinSocket_1x04_P2.54mm_Vertical | J4 |
| 1 | SW_IN1 | Button_Switch_THT:SW_PUSH_6mm_H13mm | SW1 |
| 1 | SW_IN2 | Button_Switch_THT:SW_PUSH_6mm_H13mm | SW2 |
| 1 | SW_IN3 | Button_Switch_THT:SW_PUSH_6mm_H13mm | SW3 |
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Questions
How big is the Ioboard PCB?
It measures 39.4 × 107.9 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Ioboard use?
66 parts, built around the RB521S30 and 1N5817W. 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 Ioboard KiCad files?
From the jypma/modsynth repository on GitHub, at the commit this page was made from: the board is DuinoRack/ioboard/ioboard.kicad_pcb. PCBKit opens the board in the browser, with nothing to install.
Can I use the Ioboard design in my own project?
Its repository states no licence, so its author keeps all rights: ask jypma before reusing the design.