2 layers130 × 56 mm
ML3
brucemack/microlink
An open source EchoLink/AllStarLink implementation that runs on a simple microcontroller.
73 parts18GPL-3.0
2 layers125 × 56 mm
An open source EchoLink/AllStarLink implementation that runs on a simple microcontroller.
- Size
- 125 × 56 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 73
- Nets
- 74
- Pads
- 278
- Tracks, vias
- 294, 161
- Pours
- 6
- Routed
- Yes
- KiCad
- KiCad 8.0 (file 20240108)
- Created
- 23 Jan 2024
- Updated
- 28 Oct 2025
Overview
ML2 is an open-source printed circuit board by brucemack, from the brucemack/microlink repository on GitHub, published under the GPL-3.0 licence. It is a 2-layer board of 125 × 56 mm with 73 parts on 74 nets, routed with 294 tracks and 161 vias.
It is built around the LTV-356T, BAT54S and DMG2305UX-13, with the TS04-66-55-BK-160-SMT among its other parts. Its parts include 24 resistors, 18 capacitors, 6 ICs, 4 diodes and 4 connectors. It belongs with the radio and wireless boards and the RP2040 boards of this library.
Main components
4
LTV-356T
SOP-4-2.54mm-55℃~+110℃ 1 1.2V 200mV@1mA,20mA 3.75kV 3us 4us@2mA,100Ω 50% 50mA 50mA 600% 6V 80V DC Phototransistor SOP-4-2.54mm Transistor, Photovoltaic Output Optoisolators ROHSLite-OnTransistor, Photovoltaic Output Optoisolators
BAT54S
SOT-231 Pair Series Connection 1V@100mA 200mA 2uA@25V 30V 600mA SOT-23 Schottky Diodes ROHSMDDSchottky DiodesDMG2305UX-13
SOT-23-55℃~+150℃ 1 P-Channel 1.4W 10.2nC@4.5V 20V 40mΩ@4.5V、52mΩ@2.5V 5A 77pF 808pF 85pF 900mV P-Channel SOT-23 MOSFETs ROHSDiodes IncorporatedMOSFETs
TS04-66-55-BK-160-SMT
SMD-4P,6x6mm-30℃~+80℃ 1.6N 12V 5.5mm 50mA 6mm 6mm 80,000 cycles Gull Wing Round Button SPST-NO Surface Mount,Vertical SMD-4P,6x6mm Tactile Switches ROHSCUITactile Switches
README
hw/ML3/README.mdThis file contains the details for the version 3 (ML3) of the MicroLink hardware. This is the first version that has a real enclosure so we are paying more attention to mechanical detail.
Enclosure Considerations
Connectors That Penetrate the Enclosure
- DC power connector - 5.5mm jack, male center pin positive.
- Signal/audio connector - DB9, female.
Indicators That Penetrate the Enclosure
- Three indicator LEDs - D1 Red, D3 blue, D4 green
Thermal
- The 3.3V LDO gets warm so there should be airflow in that vicinity
Change Log (V3)
R1 (17-Apr-2024)
- Moved Pi Pico W daughter card up by 1.00mm.
- Moved clear area under Pi Pico W daughter card up by 0.75mm.
- Moved J2 (5.5mm power jack) up by 2.5mm.
- Moved J1 (DB9) right by 2.5mm.
DRC Notes:
- There are 12 warnings: "Silkscreen clipped by board edge."
Parts
73| Qty | Value | Footprint | References |
|---|---|---|---|
| 7 | 47u | bruce-footprints:CPOL_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C5, C7, C8, C9, C11, C19, C20 |
| 4 | 220 | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R17, R19, R20, R22 |
| 4 | MountingHole | MountingHole:MountingHole_4mm | H1, H2, H3, H4 |
| 4 | TestPoint | TestPoint:TestPoint_Pad_2.5x2.5mm | TP2, TP3, TP4, TP5 |
| 3 | 0.1u | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C6, C18, C21 |
| 2 | 0R | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R3, R26 |
| 2 | 0R | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R18, R23 |
| 2 | 1.5k | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R1, R15 |
| 2 | 10k | bruce-footprints:POT_3362P | RV1, RV2 |
| 2 | 10k | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R5, R6 |
| 2 | 10n | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C4, C27 |
| 2 | 10u | bruce-footprints:CPOL_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C1, C2 |
| 2 | 2.2k | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R12, R13 |
| 2 | 2.7k | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R2, R16 |
| 2 | 22n | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C3, C26 |
| 2 | LTV-356T | Package_SO:SO-4_4.4x3.6mm_P2.54mm | U2, U5 |
| 2 | Transformer_1P_1S | bruce-footprints:CheapAudioTransformer | T1, T2 |
| 1 | 1k | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R9 |
| 1 | 1k | Resistor_THT:R_Axial_DIN0309_L9.0mm_D3.2mm_P2.54mm_Vertical | R24 |
| 1 | 1u | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C17 |
| 1 | 200 | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R8 |
| 1 | 270k 1% | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R11 |
| 1 | 330k 1% | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R10 |
| 1 | 33k | Resistor_THT:R_Axial_DIN0309_L9.0mm_D3.2mm_P2.54mm_Vertical | R25 |
| 1 | 4.7 | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R21 |
| 1 | 47u (Optional DC Block) | Capacitor_THT:CP_Radial_D5.0mm_P2.50mm | C10 |
| 1 | 5-12V Supply | Connector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_Vertical | J2 |
| 1 | 570 | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R4 |
| 1 | AF Out | TestPoint:TestPoint_Pad_2.5x2.5mm | TP1 |
| 1 | BAT54S | Package_TO_SOT_SMD:SOT-23 | D2 |
| 1 | Blue | LED_SMD:LED_0805_2012Metric_Pad1.15x1.40mm_HandSolder | D3 |
| 1 | Conn_01x02 | Connector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_Vertical | J4 |
| 1 | Conn_01x07 | Connector_PinHeader_2.54mm:PinHeader_1x07_P2.54mm_Vertical | J1 |
| 1 | Conn_01x20 | Connector_PinHeader_2.54mm:PinHeader_1x20_P2.54mm_Vertical | J3 |
| 1 | DMG2305UX-13 | Package_TO_SOT_SMD:SOT-23-3 | Q1 |
| 1 | Green | LED_SMD:LED_0805_2012Metric_Pad1.15x1.40mm_HandSolder | D4 |
| 1 | Jumper_2_Bridged | Connector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_Vertical | JP2 |
| 1 | LM4040DBZ-3 | Package_TO_SOT_SMD:SOT-23 | U7 |
| 1 | LMV324 (Actually LTV9161) | Package_SO:TSSOP-14_4.4x5mm_P0.65mm | U1 |
| 1 | MCP4725xxx-xCH | Package_TO_SOT_SMD:SOT-23-6 | U4 |
| 1 | NCP1117-3.3_SOT223 | Package_TO_SOT_SMD:SOT-223-3_TabPin2 | U3 |
| 1 | Red | LED_SMD:LED_0805_2012Metric_Pad1.15x1.40mm_HandSolder | D1 |
| 1 | TS04-66-55-BK-160-SMT | bruce-footprints:SW_TS04-66-55-BK-160-SMT | SW0 |
| 1 | ~ | bruce-footprints:RPi_PicoW_SMD_TH | S1 |
Questions
How big is the ML2 PCB?
It measures 125 × 56 mm and has 2 copper layers, 1.6 mm thick.
What parts does the ML2 use?
73 parts, built around the LTV-356T, BAT54S, DMG2305UX-13 and TS04-66-55-BK-160-SMT. 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 ML2 KiCad files?
From the brucemack/microlink repository on GitHub, at the commit this page was made from: the board is hw/ML2/ML2.kicad_pcb and its schematic hw/ML0/AudioIn.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the ML2 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).
More from brucemack/microlink
5- 2 layers130 × 56 mm
ML4
brucemack/microlink
An open source EchoLink/AllStarLink implementation that runs on a simple microcontroller.
73 parts18GPL-3.0 - 2 layers125 × 56 mm
ML1
brucemack/microlink
An open source EchoLink/AllStarLink implementation that runs on a simple microcontroller.
71 parts18GPL-3.0 - 2 layers100 × 59 mm
ML0
brucemack/microlink
An open source EchoLink/AllStarLink implementation that runs on a simple microcontroller.
65 parts18GPL-3.0 - 2 layers56 × 49 mm
SA818-Breakout
brucemack/microlink
An open source EchoLink/AllStarLink implementation that runs on a simple microcontroller.
21 parts18GPL-3.0
Similar boards
- 4 layers35.7 × 35.7 mm
Opendocimeter v2
georges-mars/Docimeter
A wearable redesign of the OpenDosimeter platform focused on compact electronics, custom PCB integration, embedded firmware, and practical radiation-monitoring applications.
133 parts - 2 layers170 × 140 mm
LibreVerter Controller
imendizabal/LibreVerter
Open Source Power Converter - Hardware Components
215 parts22 - 2 layers108 × 55 mm
Power control pcb
HacklabJKL/sergei_cnc2
Second version of Hacklab's custom built CNC machine
89 parts6 - 2 layers50.8 × 22.9 mm
Minimain esp32-s2
DepartmentOfAlchemy/minimain-esp32-s2
PCB files for the MiniMain ESP32-S2 in an Adafruit Feather compatible format.
39 parts4 - 2 layers60 × 52 mm
ADuM3165 USB ISOLATION
Fominsky/HIGH-SPEED-USB-ISOLATOR
High-speed USB isolator with external power based on ADuM3165/ADuM3166
68 parts4 - 2 layers100 × 100 mm
Xaar128-Driver
tuwrraphael/inkjet-printer
Inkjet printer for printing ceramic thin films: software, electronics and CAD designs
188 parts4Apache-2.0 - 2 layers25.2 × 64.4 mm
Beogram esp32
wr/beonos
Control your vintage Bang & Olufsen Beogram turntable from Home Assistant or Sonos.
19 parts2 - 2 layers230 × 160 mm
