2 layers48.4 × 106.3 mm
2 layers35.1 × 89.7 mm
Simple signal adder for Eurorack. 1U
- Size
- 35.1 × 89.7 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 36
- Nets
- 22
- Pads
- 88
- Tracks, vias
- 114, 4
- Pours
- 3
- Routed
- Yes
- KiCad
- KiCad 10.0 (file 20260206)
- Created
- 28 Apr 2026
- Updated
- 6 Jun 2026
Overview
Add is an open-source printed circuit board by thismatters, from the thismatters/EurorackAdd repository on GitHub. It is a 2-layer board of 35.1 × 89.7 mm with 36 parts on 22 nets, routed with 114 tracks and 4 vias.
It is built around the TL072 and BAT54S. Its parts include 9 resistors, 9 connectors, 3 capacitors, 2 diodes and 1 IC. It belongs with the audio and music boards of this library.
Main components
2README
README.mdSimple Add
This simple adder could come from any textbook which introduces op-amp circuits. Really simple, pretty useful too!
The KiCAD project here uses the library/footprints found in my companion repo.
Width
7hp on an Intellijel 1U rack.
Inputs
Three signal jacks
Outputs
One signal jack with the sum of the three inputs
Vendors
There are part numbers in the BOM for many of the parts (not for basic passives though) at the following vendors:
- Mouser: Needs no introduction. Get your ICs from here (or digikey).
- Tayda Electronics: Good supplier for passive components; audio jacks, and potentiometers. Their audio jacks are slightly smaller than the thonkiconn from thonk.
- Love My Switches: Has really good knobs to go on those potentiometers!
- OSHPark: Fast and (relatively) cheap PCB manufacturer. Prototype run pending.
Changelog
Parts
36| Qty | Value | Footprint | References |
|---|---|---|---|
| 6 | 100K | Resistor_SMD:R_0805_2012Metric | R3, R4, R5, R6, R7, R8 |
| 4 | Standoff | MountingHole:MountingHole_2.7mm_M2.5 | H5, H6, H7, H8 |
| 3 | mount1 | Eurorack:Mech-MountingHole | H2, H3, H4 |
| 2 | 10 | Resistor_SMD:R_0805_2012Metric | R1, R2 |
| 2 | 22u 50V | Capacitor_THT:CP_Radial_D5.0mm_P2.50mm | C1, C2 |
| 2 | BAT54S | Package_TO_SOT_SMD:SOT-23 | D1, D2 |
| 2 | Conn_01x03_Pin | Connector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_Vertical | J6, J8 |
| 2 | Conn_01x03_Socket | Connector_PinSocket_2.54mm:PinSocket_1x03_P2.54mm_Vertical | J7, J9 |
| 1 | 100n | Capacitor_SMD:C_0805_2012Metric | C3 |
| 1 | 1K | Resistor_SMD:R_0805_2012Metric | R9 |
| 1 | Conn_02x05_Odd_Even | Eurorack:PinHeader_2x05_P2.54mm_Vertical | J1 |
| 1 | TL072 | Package_SO:SOIC-8_3.9x4.9mm_P1.27mm | U1 |
| 1 | in0 | Eurorack:AudioJack2_Tayda_A-2566 | J2 |
| 1 | in0 | Eurorack:Mech-AudioJack-Hole-Input | H9 |
| 1 | in1 | Eurorack:AudioJack2_Tayda_A-2566 | J3 |
| 1 | in1 | Eurorack:Mech-AudioJack-Hole-Input | H10 |
| 1 | in2 | Eurorack:AudioJack2_Tayda_A-2566 | J4 |
| 1 | in2 | Eurorack:Mech-AudioJack-Hole-Input | H11 |
| 1 | mount0 | Eurorack:Mech-MountingHole | H1 |
| 1 | out | Eurorack:Mech-AudioJack-Hole-Output | H12 |
| 1 | out | Eurorack:AudioJack2_Tayda_A-2566 | J5 |
Similar boards
- 4 layers100 × 100 mm
- 16 layers39.6 × 110.9 mm
- 4 layers180.9 × 110 mm
- 2 layers100 × 100 mm
- 4 layers90 × 120 mm
Body
mattybrad/bjarkardottir2
A synthesizer/guitar hybrid. Somewhere between a MIDI guitar and a synthesizer. Not commercially viable. A time sink. A rabbit hole. An obsession. A mistake. An exercise in blind faith. A reason to tidy the shed.
294 parts1 - 2 layers152.1 × 64.7 mm
- 2 layers30 × 241 mm
Mix2
thismatters/EurorackMix2
Another simple signal mixing module, this time 3U and only regular patch jacks
39 parts1
Questions
How big is the Add PCB?
It measures 35.1 × 89.7 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Add use?
36 parts, built around the TL072 and BAT54S. 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 Add KiCad files?
From the thismatters/EurorackAdd repository on GitHub, at the commit this page was made from: the board is add.kicad_pcb and its schematic add.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Add design in my own project?
Its repository states no licence, so its author keeps all rights: ask thismatters before reusing the design.