4 layers58 × 100 mm
4 layers50 × 110 mm
KiCad designs for DIY Eurorack modular synthesizer modules.
- Size
- 50 × 110 mm
- Copper layers
- 4
- Thickness
- 1.6 mm
- Parts
- 62
- Nets
- 44
- Pads
- 172
- Tracks, vias
- 274, 7
- Pours
- 1
- Routed
- Yes
- KiCad
- KiCad 10.0 (file 20260206)
- Created
- 18 Oct 2026
- Updated
- 1 Nov 2026
Overview
Vco is an open-source printed circuit board by AlejandroHerr, from the AlejandroHerr/modular-synth repository on GitHub. It is a 4-layer board of 50 × 110 mm with 62 parts on 44 nets, routed with 274 tracks and 7 vias.
It is built around the BC548 and BC558. Its parts include 27 resistors, 9 capacitors, 1 diode and 1 connector.
Main components
2README
README.mdModular Synth
KiCad designs for DIY Eurorack modular synthesizer modules.
Acknowledgements
This project is based on the work of Erica Synths and Moritz Klein, in particular their collaboration on the mki x es.EDU DIY series: nine educational kits (sequencer, VCO, wavefolder, noise/S&H, mixer, VCF, envelope generator, dual VCA, and output stereo mixer with headphone amp) that walk through the design of analog synth circuits step by step. The VCO was the first kit released.
Moritz Klein's YouTube series explaining the circuit design is the main reference. All credit for the original circuit designs goes to them.
Contents
vco/: KiCad project for a sawtooth-core analog VCO (schematic and PCB), with a separate power block schematic.vcf/: KiCad project for a VCF (schematic and PCB).envelope-generator/: KiCad project for an envelope generator (schematic only for now, the PCB is not laid out yet).
References
Parts
62| Qty | Value | Footprint | References |
|---|---|---|---|
| 7 | 100k | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal | R6, R7, R9, R10, R19, R23, R24 |
| 5 | 0.1uF | Capacitor_THT:C_Rect_L4.0mm_W2.5mm_P2.50mm | C3, C4, C6, C7, C9 |
| 4 | 10k | Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P2.54mm_Vertical | VR1, VR2, VR3, VR4 |
| 3 | B100k | Synth PCB:Alpha POT Original | R1, R2, R3 |
| 2 | 10 | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal | R14, R15 |
| 2 | 1M | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal | R8, R18 |
| 2 | 1N5819 | Diode_THT:D_DO-41_SOD81_P7.62mm_Horizontal | VD1, VD2 |
| 2 | 1k | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal | R26, R27 |
| 2 | 47uFx16v | Capacitor_THT:CP_Radial_D5.0mm_P2.00mm | C1, C2 |
| 2 | 68k | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal | R20, R25 |
| 1 | -VCC | TestPoint:TestPoint_Keystone_5000-5004_Miniature | TP4 |
| 1 | 1.5k | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal | R16 |
| 1 | 100k | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P2.54mm_Vertical | R11 |
| 1 | 14k | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P2.54mm_Vertical | R21 |
| 1 | 1N4148 | Diode_THT:D_DO-35_SOD27_P7.62mm_Horizontal | D1 |
| 1 | 1V/OCT | CustomComponents:Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHoles_3d | XS2 |
| 1 | 1uF | Capacitor_THT:C_Rect_L13.5mm_W5.0mm_P10.00mm_FKS3_FKP3_MKS4 | C8 |
| 1 | 2.2nF (2n2/film) | Capacitor_THT:C_Rect_L7.2mm_W2.5mm_P5.00mm_FKS2_FKP2_MKS2_MKP2 | C5 |
| 1 | 33k | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P2.54mm_Vertical | R12 |
| 1 | 33k | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal | R13 |
| 1 | 40106 | Package_DIP:DIP-14_W7.62mm_Socket | DD1 |
| 1 | 47k | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal | R22 |
| 1 | A | TestPoint:TestPoint_Keystone_5000-5004_Miniature | TP1 |
| 1 | B | TestPoint:TestPoint_Keystone_5000-5004_Miniature | TP2 |
| 1 | B1M | Synth PCB:Alpha POT Original | R4 |
| 1 | B250k | Synth PCB:Alpha POT Original | R5 |
| 1 | BC548 | Package_TO_SOT_THT:TO-92_Inline | VT2 |
| 1 | BC558 | Package_TO_SOT_THT:TO-92_Inline | VT1 |
| 1 | C | TestPoint:TestPoint_Keystone_5000-5004_Miniature | TP6 |
| 1 | D | TestPoint:TestPoint_Keystone_5000-5004_Miniature | TP7 |
| 1 | EURORACK | CustomComponents:IDC-Header_2x05_P2.54mm_Vertical-NoSign | J1 |
| 1 | FM CV | CustomComponents:Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHoles_3d | XS3 |
| 1 | GND | TestPoint:TestPoint_Keystone_5000-5004_Miniature | TP5 |
| 1 | PULSE | CustomComponents:Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHoles_3d | XS5 |
| 1 | PULSE | TestPoint:TestPoint_Keystone_5000-5004_Miniature | TP9 |
| 1 | PWM CV | CustomComponents:Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHoles_3d | XS1 |
| 1 | SAW | CustomComponents:Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHoles_3d | XS4 |
| 1 | SAW | TestPoint:TestPoint_Keystone_5000-5004_Miniature | TP8 |
| 1 | TL074 | Package_DIP:DIP-14_W7.62mm_Socket | DA1 |
| 1 | VCC | TestPoint:TestPoint_Keystone_5000-5004_Miniature | TP3 |
| 1 | v1k | Synth PCB:Alpha POT Original | R17 |
Questions
How big is the Vco PCB?
It measures 50 × 110 mm and has 4 copper layers, 1.6 mm thick.
What parts does the Vco use?
62 parts, built around the BC548 and BC558. 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 Vco KiCad files?
From the AlejandroHerr/modular-synth repository on GitHub, at the commit this page was made from: the board is vco/vco.kicad_pcb and its schematic envelope-generator/envelope-generator.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Vco design in my own project?
Its repository states no licence, so its author keeps all rights: ask AlejandroHerr before reusing the design.
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