4 layers49 × 34 mm
C92 decoder A1
slonket/c92-decoder
An MM1/MM2/Lenz decoder for classic Märklin locomotives and the pre-mfx digital systems.
93 partsCERN-OHL-S-2.0
4 layers49 × 34 mm
C92 decoder B1
slonket/c92-decoderAn MM1/MM2/Lenz decoder for classic Märklin locomotives and the pre-mfx digital systems.
- Size
- 49 × 34 mm
- Copper layers
- 4
- Thickness
- 1 mm
- Parts
- 73
- Nets
- 49
- Pads
- 228
- Tracks, vias
- 306, 78
- Pours
- 168
- Routed
- Yes
- KiCad
- KiCad 10.0 (file 20260206)
- Created
- 13 Aug 2026
- Updated
- 16 Oct 2026
Overview
C92 decoder B1 is an open-source printed circuit board by slonket, from the slonket/c92-decoder repository on GitHub, published under the CERN-OHL-S-2.0 licence. It is a 4-layer board of 49 × 34 mm with 73 parts on 49 nets, routed with 306 tracks and 78 vias.
It is built around the STM32G031G8U6, TPS70933DBVR-MS and DSK34, with the DMN3190LDW, 3314J-1-104E and BZD27C27P among its other parts. Its parts include 18 resistors, 15 capacitors, 14 connectors, 6 diodes and 4 transistors. It belongs with the STM32 boards of this library.
Main components
7
STM32G031G8U6
UFQFPN-28(4x4)-40℃~+85℃ 1.7V~3.6V 12bit 26 32 Bit 64KB 64MHz 8KB ARM Cortex-M0+ Built-in+External FLASH UFQFPN-28(4x4) Microcontrollers (MCU/MPU/SOC) ROHSSTMicroelectronicsMicrocontrollers (MCU/MPU/SOC)
TPS70933DBVR-MS
SOT-23-5SOT-23-5 Voltage Regulators - Linear, Low Drop Out (LDO) Regulators ROHSMSKSEMIUncategorised
DSK34
SOD-123FL-55℃~+125℃ 3A 40V 500uA 520mV@3A 80A Independent SOD-123FL Schottky Diodes ROHSTWGMCSchottky Diodes
DMN3190LDW
SC-70-6(SOT-363)-55℃~+150℃ 122mΩ@10V、181mΩ@4.5V 12pF 17pF 1A 2 N-Channel 2.8V 30V 400mW 87pF 900pC@4.5V、2nC@10V N-Channel SC-70-6(SOT-363) MOSFETs ROHSDiodes IncorporatedMOSFETs
3314J-1-104E
SMD,4.5x4.5mm1 100kΩ 250mW ±100ppm/℃ ±20% SMD,4.5x4.5mm Potentiometers, Variable Resistors ROHSBournsPotentiometers & Variable Resistors
BZD27C27P
SOD-123FLZener DiodesLGEDDC114YU
SOT-363-55℃~+150℃ 1.4V 1.4V@1mA,300mV 100 100mA 2 NPN (Pre-Biased) 200mW 250MHz 300mV 50V NPN SOT-363 Digital Transistors ROHSDiodes IncorporatedDigital Transistors
README
README.mdc92-decoder
An MM1/MM2/Lenz decoder for classic Märklin locomotives and the pre-mfx digital systems.
The c92 decoder was spawned out of a passion for the classic (pre-mfx) Märklin digital systems. The controllers of this era operated with three different protocols:
- MM1 (6020, 6021, 6022, 6023)
- MM2 (6021)
- Lenz (6027, 6029)
However, no single decoder from this era can operate on all three protocols, nor with all of their capabilities. Furthermore, there is a matrix of incompatibility between different controllers and combinations of decoders using MM1 and MM2. The c92 decoder is a superset of all decoder capabilities and their respective protocols; a universal classic decoder.
Cloning
This project uses slonket-footprints as a submodule for all PCB designs. All KiCAD projects within this repository are configured to use the submodule libraries with local paths. Run the following to clone the repository with its submodule:
git clone --recurse-submodules https://github.com/slonket/c92-decoder.gitParts
73| Qty | Value | Footprint | References |
|---|---|---|---|
| 7 | 47k | Slonket_Footprints:R_0402 | R20, R21, R24, R25, R28, R29, R32 |
| 6 | 1k | Slonket_Footprints:R_0402 | R18, R19, R22, R23, R26, R27 |
| 5 | 100n | Slonket_Footprints:C_0402 | C6, C7, C9, C17, C18 |
| 5 | DSK34 | Slonket_Footprints:D_SOD-123F | D1, D2, D3, D4, D8 |
| 4 | 10u | Slonket_Footprints:C_1206 | C1, C2, C2, C2 |
| 3 | 100n | Slonket_Footprints:C_0603 | C3, C3, C3 |
| 3 | DMN3190LDW | Slonket_Footprints:U_SOT-363 | Q5, Q6, Q7 |
| 2 | 10k | Slonket_Footprints:R_0402 | R2, R31 |
| 2 | 3314J-1-104E | Slonket_Footprints:RV_BOURNS_3314J | RV1, RV2 |
| 2 | 4u7 | Slonket_Footprints:C_0402 | C4, C8 |
| 1 | 100k | Slonket_Footprints:R_0402 | R1 |
| 1 | 100u | Slonket_Footprints:CP_1210_CASE_B | C5 |
| 1 | 12k | Slonket_Footprints:R_0402 | R3 |
| 1 | 220 | Slonket_Footprints:R_0805 | R30 |
| 1 | ADDRESS | Slonket_Footprints:SW_DIP_8_P1.27 | SW1 |
| 1 | BZD27C27P | Slonket_Footprints:D_SOD-123F | D5 |
| 1 | CAP | Slonket_Footprints:J_Pad_1mm_2mm | J14 |
| 1 | DDC114YU | Slonket_Footprints:U_SOT-363 | Q4 |
| 1 | F0F_OUT | Slonket_Footprints:J_Pad_1mm_2mm | J4 |
| 1 | F0R_OUT | Slonket_Footprints:J_Pad_1mm_2mm | J5 |
| 1 | F1_OUT | Slonket_Footprints:J_Pad_1mm_2mm | J9 |
| 1 | F2_OUT | Slonket_Footprints:J_Pad_1mm_2mm | J10 |
| 1 | F3_OUT | Slonket_Footprints:J_Pad_1mm_2mm | J11 |
| 1 | F4_OUT | Slonket_Footprints:J_Pad_1mm_2mm | J12 |
| 1 | GND | Slonket_Footprints:J_Pad_1mm_2mm | J13 |
| 1 | MOTOR_L | Slonket_Footprints:J_Pad_1mm_2mm | J6 |
| 1 | MOTOR_R | Slonket_Footprints:J_Pad_1mm_2mm | J7 |
| 1 | STM32G031G8U6 | Slonket_Footprints:U_STM_UFQFPN-28_4x4_P0.5 | U2 |
| 1 | SWD | Slonket_Footprints:J_Pad_4_1.5mm | J2 |
| 1 | TPS70933DBVR | Slonket_Footprints:U_SOT-23-5 | U1 |
| 1 | TRACK_1 | Slonket_Footprints:J_Pad_1mm_2mm | J1 |
| 1 | TRACK_2 | Slonket_Footprints:J_Pad_1mm_2mm | J3 |
| 1 | VDD | Slonket_Footprints:J_Pad_1mm_2mm | J8 |
The 62 most common of 73 parts.
Questions
How big is the C92 decoder B1 PCB?
It measures 49 × 34 mm and has 4 copper layers, 1 mm thick.
What parts does the C92 decoder B1 use?
73 parts, built around the STM32G031G8U6, TPS70933DBVR-MS, DSK34 and DMN3190LDW. 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 C92 decoder B1 KiCad files?
From the slonket/c92-decoder repository on GitHub, at the commit this page was made from: the board is hardware/c92_decoder_B1/c92_decoder_B1.kicad_pcb and its schematic hardware/c92_decoder_A1/c92_decoder_A1.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the C92 decoder B1 design in my own project?
Its repository publishes it under the CERN-OHL-S-2.0 licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).
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