4 layers95 × 43 mm
Reflow Plate Controller
incend1um3/USB-C-PD-Reflow-Plate
300W PCB Reflow Plate with USB-C PD Support
83 parts2CERN-OHL-S-2.0
2 layers122 × 84 mm
SYS StepAtten
schilkp/SYS_StepAttenA 127 Step Relay Step-Attenuator and 4-way input switcher designed to fit into a Schiit SYS enclosure.
- Size
- 122 × 84 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 145
- Nets
- 117
- Pads
- 505
- Tracks, vias
- 1,715, 216
- Pours
- 7
- Routed
- Yes
- KiCad
- KiCad 5 (file 20171130)
- Created
- 8 Mar 2020
- Updated
- 6 Feb 2026
Overview
SYS StepAtten is an open-source printed circuit board by schilkp, from the schilkp/SYS_StepAtten repository on GitHub, published under the MIT licence. It is a 2-layer board of 122 × 84 mm with 145 parts on 117 nets, routed with 1,715 tracks and 216 vias.
It is built around the STM32F030K6T6, MC34063AD and LM317, with the SD03 among its other parts. Its parts include 58 resistors, 20 diodes, 16 switches, 14 transistors and 13 capacitors. It belongs with the home automation and IoT boards and the STM32 boards of this library.
Main components
4
STM32F030K6T6
LQFP-32(7x7)-40℃~+85℃ 12bit 2.4V~3.6V 26 32 Bit 32KB 48MHz 4KB ARM Cortex-M0 Built-in FLASH LQFP-32(7x7) Microcontrollers (MCU/MPU/SOC) ROHSSTMicroelectronicsMicrocontrollers (MCU/MPU/SOC)
MC34063AD
SOIC-80℃~+70℃@(TA) 1 1.25V~40V 1.5A 100kHz 3V~40V Adjustable Boost、Buck Buck、Boost Built-in No SOIC-8 DC-DC Converters ROHSonsemiDC-DC Converters
LM317
SOT-223-40℃~+85℃@(Ta) 0.003%Vout 1 1.3V~37V 1A 40V 80dB@(120Hz) Adjustable Positive Short Circuit Protection、Thermal shutdown SOT-223 Voltage Regulators - Linear, Low Drop Out (LDO) Regulators ROHSJSMSEMIVoltage Regulators - Linear, Low Drop Out (LDO) Regulators
SD03
SOD-323ESD And Surge Protection (TVS/ESD)LGE
README
README.mdSYS StepAtten
Philipp Schilk
A 127 Step Relay Step-Attenuator and 4-way input switcher designed to fit into a Schiit SYS enclosure.
Specifications
| Spec | Value |
|---|---|
| Inputs | 2x Stereo 3.5mm, 2x Stereo RCA |
| Attenuator Type | Constant input impedance |
| Expected Input Impedance | 10K (can be adjusted) |
| Steps | 127 + Relay Mute |
| Power Input | 9Vdc, center positive barrel jack. 500mA+ |
| Power Consumption | Max 2.25W (250mA at 9VDc) |
| Control | Internal controls or wired remote control |
Grounding
All inputs are fully isolated from each other. RCA grounds can be kept seperate or joined. (Internal Jumper) Audio ground can be kept seperate or joined to digital ground (Internal Jumper)
Remote Control
Remote Control connector pinout (looking at connector from back of unit):
| 3V | GND |
|---|---|
| Sense | Poti |
A remote consists of a potentiometer between 3V and GND with wiper connected to 'Poti' A 10K resistor has to be placed between GND and Sense for the remote to be detected. If the remote features a switch, it should short Sense to GND.
Riser Board
Design files for the 3.5mm Connector Riser board can be found here.
Switch Selection
The SYS is normally fitted with a toggle switch (ALPS SPUN191400), but a momentary version of that switch also exists (ALPS SPUN190900).
The momentary switch is probably the better choice, but just in case one wants to harvest as many parts as possible from an original SYS, both are supported by the firmware.
The internal Jumper CFG1 is used to indicate which kind is installed.
| Switch | CFG1 Setting |
|---|---|
| Momentary (ALPS SPUN190900) | 0 |
| Toggle (ALPS SPUN191400) | 1 |
Note that the unit has to be turned off and on again for this setting to take effect.
Schematics, Gerbers, BOMs, ...
See Github Releases.
Parts
145| Qty | Value | Footprint | References |
|---|---|---|---|
| 14 | 10K | Resistor_SMD:R_0603_1608Metric | R1, R17, R34, R35, R36, R37, R40, R41, R44, R45, R46, R47, R57, R58 |
| 14 | 1N4001 | Diode_SMD:D_SOD-123F | D5, D11, D12, D13, D14, D15, D16, D17, D18, D19, D20, D21, D22, D23 |
| 14 | 2N7002 | Package_TO_SOT_SMD:SOT-23 | Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8, Q9, Q10, Q11, Q12, Q13, Q14 |
| 14 | TQ2SA | Panasonic_TQ2SA:Panasonic_TQ2SA | K1, K2, K3, K4, K5, K6, K7, K8, K9, K10, K11, K12, K13, K14 |
| 8 | 0u1 | Capacitor_SMD:C_0603_1608Metric | C1, C2, C4, C8, C10, C13, C14, C16 |
| 4 | 1K | Resistor_SMD:R_0603_1608Metric | R4, R5, R6, R7 |
| 4 | SD03 | Diode_SMD:D_SOD-323 | D3, D4, D6, D7 |
| 2 | 0R | Resistor_SMD:R_0603_1608Metric | R48, R49 |
| 2 | 100R | Resistor_SMD:R_0603_1608Metric | R2, R3 |
| 2 | 12K | Resistor_SMD:R_0603_1608Metric | R50, R52 |
| 2 | 160K | Resistor_SMD:R_0603_1608Metric | R38, R39 |
| 2 | 18K | Resistor_SMD:R_0603_1608Metric | R22, R23 |
| 2 | 1K1 | Resistor_SMD:R_0603_1608Metric | R32, R33 |
| 2 | 1K87 | Resistor_SMD:R_0603_1608Metric | R13, R14 |
| 2 | 261R | Resistor_SMD:R_0603_1608Metric | R9, R10 |
| 2 | 2K | Resistor_SMD:R_0603_1608Metric | R28, R29 |
| 2 | 39K | Resistor_SMD:R_0603_1608Metric | R26, R27 |
| 2 | 3K6 | Resistor_SMD:R_0603_1608Metric | R24, R25 |
| 2 | 560R | Resistor_SMD:R_0603_1608Metric | R42, R43 |
| 2 | 5K | Potentiometer_THT:Potentiometer_Bourns_3296W_Vertical | R51, R53 |
| 2 | 5K9 | Resistor_SMD:R_0603_1608Metric | R20, R21 |
| 2 | 6K49 | Resistor_SMD:R_0603_1608Metric | R18, R19 |
| 2 | 82K | Resistor_SMD:R_0603_1608Metric | R30, R31 |
| 2 | 8K25 | Resistor_SMD:R_0603_1608Metric | R15, R16 |
| 2 | 9K53 | Resistor_SMD:R_0603_1608Metric | R11, R12 |
| 2 | A/D GND Jumper | Connector_PinHeader_2.54mm:PinHeader_2x03_P2.54mm_Vertical | J9, J10 |
| 1 | 0.15A | Fuse:Fuse_1206_3216Metric | F2 |
| 1 | 0R33 / 0.5W min | Resistor_SMD:R_1210_3225Metric | R54 |
| 1 | 1000u | Capacitor_SMD:CP_Elec_10x10.5 | C3 |
| 1 | 10K Linear | Potentiometer_THT:Potentiometer_Alps_RK09K_Single_Horizontal | RV1 |
| 1 | 1A | Fuse:Fuse_1206_3216Metric | F1 |
| 1 | 1K2 | Resistor_SMD:R_0603_1608Metric | R56 |
| 1 | 1K5 | Resistor_SMD:R_0603_1608Metric | R8 |
| 1 | 1N5819 | Diode_SMD:D_SOD-123F | D1 |
| 1 | 1u | Capacitor_SMD:C_0603_1608Metric | C15 |
| 1 | 1uf | Capacitor_SMD:C_0603_1608Metric | C5 |
| 1 | 22uH/800mA | Inductor_SMD:L_Taiyo-Yuden_MD-4040 | L1 |
| 1 | 3K8 | Resistor_SMD:R_0603_1608Metric | R55 |
| 1 | 470u | Capacitor_SMD:CP_Elec_8x10.5 | C7 |
| 1 | 47pf | Capacitor_SMD:C_0603_1608Metric | C6 |
| 1 | ADJ_L | Connector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_Vertical | J11 |
| 1 | ADJ_R | Connector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_Vertical | J12 |
| 1 | ARM SWD | Connector_PinHeader_1.27mm:PinHeader_2x05_P1.27mm_Vertical_SMD | J8 |
| 1 | AUX-1-2 | 3.5mm_RiserPCB:3.5mm_RiserPCB | J4 |
| 1 | BarrelPolarity_CenterPos | BarrelPolarity_3mm:BarrelPolarity_3mm_CenterPos | G1 |
| 1 | Barrel_Jack 9Vdc | Connector_BarrelJack:BarrelJack_Horizontal | J5 |
| 1 | INPUT_SWITCH | ALPS_SPUN191400:ALPS_SPUN191400 | SW1 |
| 1 | LED_RGBA | RGB_LED_1.6x1.6x0:RGB_LED_1.6x1.6x0.6 | D10 |
| 1 | LM317 | Package_TO_SOT_SMD:TO-252-2 | U1 |
| 1 | MC34063AD | Package_SO:SOIC-8_3.9x4.9mm_P1.27mm | U2 |
| 1 | MH 1 | MountingHole_4.3mm_M4_ReducedSize:MountingHole_4.3mm_M4_Pad_Via | H2 |
| 1 | ON/OFF | Connector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_Vertical | SW2 |
| 1 | POT_EXT Conn | Connector_PinHeader_2.54mm:PinHeader_2x02_P2.54mm_Horizontal | J6 |
| 1 | RCA-1 | RCA_KobiCon_161-4220-E:RCA_KobiCon_161-4220-E | J2 |
| 1 | RCA-2 | RCA_KobiCon_161-4220-E:RCA_KobiCon_161-4220-E | J3 |
| 1 | RCA-Out | RCA_KobiCon_161-4220-E:RCA_KobiCon_161-4220-E | J1 |
| 1 | STM32f030K6T6 | Package_QFP:LQFP-32_7x7mm_P0.8mm | U4 |
| 1 | cfg jumper | Connector_PinHeader_2.54mm:PinHeader_2x03_P2.54mm_Vertical | J7 |
| 1 | debug | TestPoint:TestPoint_Pad_2.5x2.5mm | TP2 |
| 1 | gnd_case | Resistor_SMD:R_0603_1608Metric | JP1 |
| 1 | nrst | TestPoint:TestPoint_Pad_2.5x2.5mm | TP1 |
Questions
How big is the SYS StepAtten PCB?
It measures 122 × 84 mm and has 2 copper layers, 1.6 mm thick.
What parts does the SYS StepAtten use?
145 parts, built around the STM32F030K6T6, MC34063AD, LM317 and SD03. 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 SYS StepAtten KiCad files?
From the schilkp/SYS_StepAtten repository on GitHub, at the commit this page was made from: the board is KiCad/SYS_StepAtten/SYS_StepAtten.kicad_pcb. PCBKit opens the board in the browser, with nothing to install.
Can I use the SYS StepAtten design in my own project?
Its repository publishes it under the MIT licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).
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