2 layers114.2 × 100 mm Envelope pcb, the printed circuit board in 3D

Envelope pcb

A collection of free & open source DIY synthesizer module designs for Eurorack

Size: 114.2 × 100 mm
Copper layers: 2
Thickness: 1.6 mm
Parts: 61
Nets: 87
Pads: 231
Tracks, vias: 461, 0
Pours: 2
Routed: Yes
KiCad: KiCad 8.0 (file 20240108)
Created: 17 Dec 2019
Updated: 3 Nov 2026

Overview

Envelope pcb is an open-source printed circuit board by QuinnFreedman, from the QuinnFreedman/modular repository on GitHub. It is a 2-layer board of 114.2 × 100 mm with 61 parts on 87 nets, routed with 461 tracks and 0 vias.

It is built around the MCP4922-E/P, MCP6004-E/P and TL1105SPF250Q. Its parts include 26 resistors, 14 connectors, 4 diodes, 3 capacitors and 2 ICs. It belongs with the audio and music boards and the AVR (ATmega, ATtiny) boards of this library.

Main components

README

README.md

This project is an attempt to make Eurorack modular synthesis affordable and accessible to everyone.

This repository contains open source software and hardware schematics for Eurorack modules which are designed to be assembled easily and cheaply without any technical knowledge. Every module should be able to be assembled for around $20 in about an hour of work, even with limited experience.

To get started, check out some of the links below. Or get in touch! Send me a message at freemodular@gmail.com. Follow my reddit, Etsy shop, or GitHub.

Happy travels on your modular journey!

Go to the website to see more

Modules

{% include_relative docs/modules.md %}

Parts

Qty	Value	Footprint	References
12	100kΩ	Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	R1, R3, R5, R7, R13, R14, R15, R16, R17, R18, R19, R20
8	THONKICONN	FreeModular:THONKICONN	J1, J2, J3, J4, J5, J6, J7, J8
4	10kΩ	Potentiometer_THT:Potentiometer_Alpha_RD901F-40-00D_Single_Vertical	RV1, RV2, RV3, RV4
4	10kΩ	Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	R21, R22, R23, R24
4	200kΩ	Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	R2, R4, R6, R8
4	2kΩ	Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	R9, R10, R11, R12
2	100nF	Capacitor_THT:C_Disc_D4.7mm_W2.5mm_P5.00mm	C2, C3
2	1kΩ	Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	R25, R26
2	2N3904	Package_TO_SOT_THT:TO-92L_Inline_Wide	Q1, Q2
2	Board	kikit:Board	B1, B2
1	10uF	Capacitor_THT:CP_Radial_D4.0mm_P1.50mm	C1
1	Arduino_Nano_v3.x	Module:Arduino_Nano	A1
1	BLUE	LED_THT:LED_D3.0mm	D2
1	Conn_01x07_Pin	Connector_PinSocket_2.54mm:PinSocket_1x07_P2.54mm_Vertical	J11
1	Conn_01x07_Socket	Connector_PinSocket_2.54mm:PinSocket_1x07_P2.54mm_Vertical	J12
1	Conn_01x08_Pin	Connector_PinSocket_2.54mm:PinSocket_1x08_P2.54mm_Vertical	J9
1	Conn_01x08_Socket	Connector_PinSocket_2.54mm:PinSocket_1x08_P2.54mm_Vertical	J10
1	Conn_02x02_Odd_Even	Connector_PinHeader_2.54mm:PinHeader_2x03_P2.54mm_Vertical	J14
1	Eurorack_2x8_Power	Connector_IDC:IDC-Header_2x08_P2.54mm_Vertical	J13
1	GREEN	LED_THT:LED_D3.0mm	D4
1	MCP4922	Package_DIP:DIP-14_W7.62mm	U1
1	MCP6004	Package_DIP:DIP-14_W7.62mm	U2
1	Pin_D0.7mm_L6.5mm_W1.8mm_FlatFork	Connector_Pin:Pin_D0.7mm_L6.5mm_W1.8mm_FlatFork	G2
1	RED	LED_THT:LED_D3.0mm	D3
1	TL1105SPF250Q	Button_Switch_THT:SW_PUSH_6mm_H13mm	SW1
1	YELLOW	LED_THT:LED_D3.0mm	D1
1	logo_small	FreeModular:logo_small	G1

Questions

How big is the Envelope pcb PCB?

It measures 114.2 × 100 mm and has 2 copper layers, 1.6 mm thick.

What parts does the Envelope pcb use?

61 parts, built around the MCP4922-E/P, MCP6004-E/P and TL1105SPF250Q. 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 Envelope pcb KiCad files?

From the QuinnFreedman/modular repository on GitHub, at the commit this page was made from: the board is modules/Envelope/PCBs/envelope_pcb/envelope_pcb.kicad_pcb. PCBKit opens the board in the browser, with nothing to install.

Can I use the Envelope pcb design in my own project?

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

Category and platform

Audio and music AVR (ATmega, ATtiny)

Topics

eurorack music modular

Project files

Show this board on your page

A live frame, for any web page

<iframe src="https://pcbkit.io/embed/boards/quinnfreedman-modular-envelope-pcb" title="Envelope pcb 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/quinnfreedman-modular-envelope-pcb.jpg" alt="Envelope pcb" width="1200" height="900">

A picture that opens the board, for a README

[![Envelope pcb](https://pcbkit.io/embed/boards/quinnfreedman-modular-envelope-pcb.jpg?size=s)](https://pcbkit.io/boards/quinnfreedman-modular-envelope-pcb)

Source

Repository: QuinnFreedman/modular
Board file: modules/Envelope/PCBs/envelope_pcb/envelope_pcb.kicad_pcb
Commit: c78d208
Homepage: freemodular.org
Licence: Not stated

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