2 layers125 × 56 mm
ML2
brucemack/microlink
An open source EchoLink/AllStarLink implementation that runs on a simple microcontroller.
73 parts18GPL-3.0
2 layers130 × 56 mm
An open source EchoLink/AllStarLink implementation that runs on a simple microcontroller.
- Size
- 130 × 56 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 73
- Nets
- 76
- Pads
- 284
- Tracks, vias
- 322, 163
- Pours
- 6
- Routed
- Yes
- KiCad
- KiCad 9.0 (file 20241229)
- Created
- 23 Jan 2024
- Updated
- 28 Oct 2025
Overview
ML4 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 130 × 56 mm with 73 parts on 76 nets, routed with 322 tracks and 163 vias.
It is built around the LTV-356T, LM1117MP-3.3 and LM4040D30IDBZR, with the SM-LP-5001, BAT54S and DMG2305UX-13 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
8
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
LM1117MP-3.3
SOT-2230℃~+125℃@(Ta) 1 1.2V@(800mA) 15V 3.3V 5mA 75dB@(120Hz) 800mA 99uVrms Fixed Over Current Protection、Over Temperature Protection Positive SOT-223 Voltage Regulators - Linear, Low Drop Out (LDO) Regulators ROHSTexas InstrumentsVoltage Regulators - Linear, Low Drop Out (LDO) Regulators
LM4040D30IDBZR
SOT-23-40℃~+85℃@(Ta) 150ppm/℃ 15mA 35uVrms 3V 82uA Fixed Parallel ±1% SOT-23 Voltage Reference ROHSTexas InstrumentsVoltage ReferenceSM-LP-5001
SMD-6P,12.8x9mmSMD-6P,12.8x9mm Audio Transformers ROHSBournsAudio TransformersBAT54S
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
PJ-102AH
插件-25℃~+85℃ 24V 2mm 5A 6.5mm DC Power Jack Right Angle Plugin DC Power Connectors ROHSCUIDC Power Connectors
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 |
|---|---|---|---|
| 8 | 47u | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C5, C7, C8, C9, C11, C17, C19, C20 |
| 4 | 2.2k | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R5, R6, R12, R13 |
| 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 |
| 3 | 100 | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R17, R20, R22 |
| 2 | 1.5k | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R1, R15 |
| 2 | 10n | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C4, C27 |
| 2 | 2.7k | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R2, R16 |
| 2 | 220 | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R8, R19 |
| 2 | 22n | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C3, C26 |
| 2 | 22u | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C1, C2 |
| 2 | 50k | bruce-footprints:POT_3362P | RV1, RV2 |
| 2 | LTV-356T | Package_SO:SO-4_4.4x3.6mm_P2.54mm | U2, U5 |
| 2 | SM-LP-5001 | bruce-footprints:TRAN6_SM-LP-5001_BRN | TR1, TR2 |
| 1 | 0R | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R18 |
| 1 | 0R | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R3 |
| 1 | 0R 1206 | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R26 |
| 1 | 10 | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R7 |
| 1 | 1k | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R9 |
| 1 | 2,.2k | Resistor_THT:R_Axial_DIN0309_L9.0mm_D3.2mm_P2.54mm_Vertical | R24 |
| 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 | 39k | 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 | 620 | Resistor_THT:R_Axial_DIN0309_L9.0mm_D3.2mm_P2.54mm_Vertical | 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_01x20 | Connector_PinHeader_2.54mm:PinHeader_1x20_P2.54mm_Vertical | J3 |
| 1 | DE9_Receptacle | bruce-footprints:CONN_A-DF 09 A&slash_KG-T2S_ASM | J1 |
| 1 | DMG2305UX-13 | Package_TO_SOT_SMD:SOT-23_Handsoldering | Q1 |
| 1 | Green | LED_SMD:LED_0805_2012Metric_Pad1.15x1.40mm_HandSolder | D4 |
| 1 | LM1117MP-3.3 | Package_TO_SOT_SMD:SOT-223-3_TabPin2 | U3 |
| 1 | LM4040D30IDBZR | Package_TO_SOT_SMD:SOT-23 | U7 |
| 1 | MCP4725A0T-E/CH | Package_TO_SOT_SMD:SOT-23-6 | U4 |
| 1 | PJ-102AH | bruce-footprints:Power_5.5mm_CUI_PJ-102AH | J2 |
| 1 | Red | LED_SMD:LED_0805_2012Metric_Pad1.15x1.40mm_HandSolder | D1 |
| 1 | SolderJumper_2_Bridged | Jumper:SolderJumper-2_P1.3mm_Bridged_Pad1.0x1.5mm | JP1 |
| 1 | TLV9164PWR | Package_SO:TSSOP-14_4.4x5mm_P0.65mm | U1 |
| 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 ML4 PCB?
It measures 130 × 56 mm and has 2 copper layers, 1.6 mm thick.
What parts does the ML4 use?
73 parts, built around the LTV-356T, LM1117MP-3.3, LM4040D30IDBZR and SM-LP-5001. 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 ML4 KiCad files?
From the brucemack/microlink repository on GitHub, at the commit this page was made from: the board is hw/ML4/ML4.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 ML4 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
ML3
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 layers70 × 54 mm
- 6 layers100 × 100 mm
- 2 layers78 × 622 mm
- 2 layers50 × 45 mm
- 2 layers36.3 × 21.8 mm
Ic-705 audio interface
project802/ic-705_audio_interface
This project was done as a learning exercise for me, and a way to have some fun. I wanted to use my IC-705 with just an iPhone to drive digital mode communications, but limitations of both the radio and the phone meant…
11 parts - 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 - 4 layers46 × 110 mm
Aware01 h7 rev2 0
95lux/aware01
Aarebot is a dynamic realtime sampler built as a Eurorack module. At its core is a stereo tape-style engine with a hot-swapping record/playback buffer - this enables to record and play simultaneously.
158 parts15GPL-3.0 - 2 layers80 × 40 mm
