2 layers266.7 × 81 mm Stepper synth, the printed circuit board in 3D

Stepper synth

An electronic instrument that uses stepper motors to make music

Size: 266.7 × 81 mm
Copper layers: 2
Thickness: 1.6 mm
Parts: 224
Nets: 183
Pads: 903
Tracks, vias: 1,559, 264
Pours: 2
Routed: Yes
KiCad: KiCad 9.0 (file 20241229)
Created: 4 Dec 2025
Updated: 31 Dec 2025

Overview

Stepper synth is an open-source printed circuit board by udu3324, from the udu3324/stepper-synth repository on GitHub, published under the GPL-3.0 licence. It is a 2-layer board of 266.7 × 81 mm with 224 parts on 183 nets, routed with 1,559 tracks and 264 vias.

It is built around the TMC2209-LA, CD74HC4067M and TPS2115APW, with the WS2812B, SS14 and USB4105-GF-A among its other parts. Its parts include 83 capacitors, 49 ICs, 27 resistors, 9 diodes and 8 connectors. It belongs with the robots and motor control and audio and music boards and the ESP32 boards of this library.

Main components

README

README.md

stepper-synth

An electronic instrument that uses stepper motors to make music. Powered by the esp32 ecosystem, it is a synthesizer with 3 octaves with velocity support using hall effect sensors. It is inspired by the musician/engineer Love Hultén.

Why I Made This

There's so many electronic instruments that make sounds purely through cables and rely on other devices to output to them. Instead, what if I used the power of stepper motors to make sound and create a standalone device? I notice how harmonic these motors could be while 3d printing, they sometimes have a noticable pattern and variable pitch that can be utilized.

Photos

render sc1 sc2

PCB

pcb 3d pcb

Schematics

Bill of Materials

Sadly I was aiming for tier 2 budget but didn't realize how much tariffs and shipping would push me out of it 😭

Interactive Link: google sheets

Part	Cost	Count	Count Cost	Note	Status	Link
Regular Switches		2	0		On hand	https://divinikey.com/collections/linear-switches
Hall Effect Switches	$13.50	2	$27.00	18x per		https://divinikey.com/collections/hall-effect-switches/products/gateron-magnetic-genty-he-switches
Rotary Encoder		3	0		On hand	https://www.mouser.com/ProductDetail/Alps-Alpine/EC11E183440C?qs=YMSFtX0bdJC6PoDF7K4k%252Bg%3D%3D
Button		1	0		On hand	https://www.digikey.com/en/products/detail/te-connectivity-alcoswitch-switches/1825910-6/1632536
WS2812	$0.80	8	$6.40	neopixels		https://www.mouser.com/ProductDetail/SparkFun/COM-24837?qs=dbcCsuKDzFUNFvBH5VYBTw%3D%3D
LRS-350-24		1	0	power supply	On hand	https://www.digikey.com/en/products/detail/mean-well-usa-inc/LRS-350-24/7705034
IEC320 C14 Switch		1	0	cable input	On hand	https://www.aliexpress.us/item/3256804155743663.html
Screw Terminal	$0.35	1	$0.35			https://www.mouser.com/ProductDetail/Same-Sky/TB002-500-02BE?qs=vLWxofP3U2x9716kcgva%2Fw%3D%3D
Nema 17 0.8 Motors		4	$0.00	reused prusas	On hand	https://www.omc-stepperonline.com/nema-17-bipolar-0-9deg-46ncm-65-1oz-in-2a-2-9v-42x42x48mm-4-wires-17hm19-2004s
ESP32-S3-WROOM-2	$11.87	1	$11.87	microcontroller		https://www.mouser.com/ProductDetail/Espressif-Systems/ESP32-S3-WROOM-2-N32R16V?qs=%252BHhoWzUJg4Kf%2FwmS40wg%252BQ%3D%3D
Solder Paste Syringe	$16.95	1	$16.95	mine dried out		https://www.mouser.com/ProductDetail/Chip-Quik/TS391LT?qs=1mbolxNpo8dzjCIcP7S2Kg%3D%3D
150uF Polarized Capacitor	$1.40	4	$5.60			https://www.mouser.com/ProductDetail/Panasonic/EEH-AZA1E151B?qs=sGAEpiMZZMsh%252B1woXyUXj7hTFrnMyX90Ysfyv/7vmlA%3D
Female Pin Headers	$0.84	2	$1.68			https://www.mouser.com/ProductDetail/Samtec/CES-102-02-G-S?qs=0lQeLiL1qyY%2FrwXtinpohw%3D%3D
Hot-swap Switch Plug		2	0		On hand	https://www.gateron.com/products/gateron-low-profile-switch-hot-swap-pcb-socket?srsltid=AfmBOop0aFTt__A_sBY2D5LC6GJteiDSPO9H3qEt2M2Dhil_s2AUwsRR&VariantsId=10234
M3x5mm Screws		18			On hand	https://www.moddiy.com/products/1264/M3.0-x-5mm-Black-Screws-(KM3X5).html?srsltid=AfmBOorXbTDS16CG3UQ8tCHJn64vKhPv2bQRUskhtAbTRuyfojuJ6yEs_D8

PCB Prototype	$12.20
PCBA	$90.68			6 extended parts only
Merchandise Total	$102.88			pcb + pcba
Shipping Estimate	$55.24
Duties & Taxes (US)	$46.30
Sales Tax	$13.04
Grand Total	$217.46			only count this

	$217.46		69.85

Needed for Grant	$287.31			not including shipping and taxes from mouser/divinikey!!!
				though mouser shipping should be really low

Parts

224

Qty	Value	Footprint	References
36	0.01µF	Capacitor_SMD:C_0805_2012Metric	C27, C28, C29, C30, C31, C32, C33, C34, C35, C36, C37, C38, C39, C40, C41, C42 +20
36	DRV5055A3xDBZxQ1	Package_TO_SOT_SMD:SOT-23	U10, U11, U12, U13, U14, U15, U16, U17, U18, U19, U20, U21, U22, U23, U24, U25 +20
22	100nF	Capacitor_SMD:C_0805_2012Metric	C7, C12, C14, C20, C21, C26, C63, C64, C65, C66, C67, C68, C69, C70, C71, C72 +6
8	220Ω	Resistor_SMD:R_0805_2012Metric	R14, R15, R16, R17, R18, R19, R20, R21
8	WS2812B	LED_SMD:LED_WS2812B_PLCC4_5.0x5.0mm_P3.2mm	D2, D3, D4, D5, D6, D7, D8, D9
6	10kΩ	Resistor_SMD:R_0805_2012Metric	R1, R2, R11, R12, R13, R26
4	0.1μF	Capacitor_SMD:C_0805_2012Metric	C3, C4, C82, C83
4	150µF	Capacitor_THT:C_Radial_D10.0mm_H12.5mm_P5.00mm	C9, C10, C19, C25
4	1kΩ	Resistor_SMD:R_0805_2012Metric	R8, R10, R23, R25
4	2.2µF	Capacitor_SMD:C_0805_2012Metric	C11, C16, C22, C78
4	20kΩ	Resistor_SMD:R_0805_2012Metric	R7, R9, R22, R24
4	22nF	Capacitor_SMD:C_0805_2012Metric	C13, C17, C23, C79
4	4.7µF	Capacitor_SMD:C_0805_2012Metric	C15, C18, C24, C80
4	Conn_01x04_Pin	Connector_PinHeader_2.54mm:PinHeader_1x04_P2.54mm_Vertical	J3, J4, J5, J6
4	TMC2209-LA	Package_DFN_QFN:VQFN-28-1EP_5x5mm_P0.5mm_EP3.7x3.7mm_ThermalVias	U3, U4, U5, U6
3	CD74HC4067M	Package_SO:SOIC-24W_7.5x15.4mm_P1.27mm	U45, U46, U48
3	MCP6002-xMC	Package_DFN_QFN:DFN-8-1EP_3x2mm_P0.5mm_EP1.75x1.45mm	U43, U44, U47
3	RotaryEncoder_Switch	Rotary_Encoder:RotaryEncoder_Alps_EC11E-Switch_Vertical_H20mm	SW2, SW5, SW6
2	0Ω	Resistor_SMD:R_0805_2012Metric	R3, R4
2	5.1kΩ	Resistor_SMD:R_0805_2012Metric	R5, R6
2	SW_Push_45deg	EasyEDA:TH_L10.9-W5.9-CPG151101S11	SW3, SW4
2	TestPoint	MountingHole:MountingHole_3.2mm_M3_Pad	TP1, TP2
1	0.47μF	Capacitor_SMD:C_0805_2012Metric	C5
1	100kΩ	Resistor_SMD:R_0805_2012Metric	R27
1	10μF	Capacitor_SMD:C_0805_2012Metric	C2
1	1uF	Capacitor_SMD:C_0805_2012Metric	C1
1	4.7μF	Capacitor_SMD:C_0805_2012Metric	C81
1	47μF	Capacitor_SMD:C_0805_2012Metric	C6
1	Conn_01x02_Pin	Connector_PinSocket_2.54mm:PinSocket_1x02_P2.54mm_Vertical	J8
1	Conn_01x02_Socket	Connector_PinSocket_2.54mm:PinSocket_1x02_P2.54mm_Vertical	J9
1	ESP32-S3-WROOM-2	RF_Module:ESP32-S3-WROOM-2	U1
1	LM3940IMPX-3.3/NOPB	EasyEDA:SOT-223-4_L6.5-W3.5-P2.30-LS7.0-BR	U2
1	LOGO	1_udu_lib:stepper_drawing_f	G***
1	LOGO	1_udu_lib:stepper_drawing_b	G***
1	LRS-350-24	TerminalBlock_MetzConnect:TerminalBlock_MetzConnect_Type055_RT01502HDWU_1x02_P5.00mm_Horizontal	J2
1	SS14	Diode_SMD:D_SMA	D1
1	SW_SPST	Button_Switch_THT:SW_PUSH_6mm	SW1
1	TPS2115APW	2_udu_lib:PW8	U49
1	USB4105	Connector_USB:USB_C_Receptacle_GCT_USB4105-xx-A_16P_TopMnt_Horizontal	J1

The 186 most common of 224 parts.

Questions

How big is the Stepper synth PCB?

It measures 266.7 × 81 mm and has 2 copper layers, 1.6 mm thick.

What parts does the Stepper synth use?

224 parts, built around the TMC2209-LA, CD74HC4067M, TPS2115APW and WS2812B. 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 Stepper synth KiCad files?

From the udu3324/stepper-synth repository on GitHub, at the commit this page was made from: the board is pcb/steppersynth/steppersynth.kicad_pcb and its schematic pcb/steppersynth/arp_mod.kicad_sch. PCBKit opens the board in the browser, with nothing to install.

Can I use the Stepper synth design in my own project?

Its repository publishes it under the GPL-3.0 licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).

Category and platform

Robots and motor control Audio and music ESP32

Project files

Show this board on your page

A live frame, for any web page

<iframe src="https://pcbkit.io/embed/boards/udu3324-stepper-synth" title="Stepper synth 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/udu3324-stepper-synth.jpg" alt="Stepper synth" width="1200" height="900">

A picture that opens the board, for a README

[![Stepper synth](https://pcbkit.io/embed/boards/udu3324-stepper-synth.jpg?size=s)](https://pcbkit.io/boards/udu3324-stepper-synth)

Source

Repository: udu3324/stepper-synth
Board file: pcb/steppersynth/steppersynth.kicad_pcb
Commit: bcdcb2d
Licence: GPL-3.0

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