2 layers104 × 60 mm UTAC PCB, the printed circuit board in 3D

UTAC PCB

4-channel smart relay control board with ESP32-C3 SuperMini - KiCad PCB Design v0.2.0

Size: 104 × 60 mm
Copper layers: 2
Thickness: 1.6 mm
Parts: 59
Nets: 52
Pads: 168
Tracks, vias: 444, 5
Routed: Yes
KiCad: KiCad 10.0 (file 20260206)
Created: 8 May 2026
Updated: 8 May 2026

Overview

UTAC PCB is an open-source printed circuit board by X-zeed, from the X-zeed/UTAC-PCB repository on GitHub. It is a 2-layer board of 104 × 60 mm with 59 parts on 52 nets, routed with 444 tracks and 5 vias.

It is built around the HLK-10M05, MMBT2222A and MRA4003T3G-MS, with the SRA-05VDC-CL among its other parts. Its parts include 19 resistors, 11 connectors, 9 diodes, 8 capacitors and 4 transistors. It belongs with the home automation and IoT boards and the ESP32 and RISC-V boards of this library.

Main components

README

README.md

UTAC PCB — v0.2.0

4-Channel Smart Relay Control Board powered by ESP32-C3 SuperMini with onboard AC–DC power supply.

Overview

UTAC PCB is a compact, mains-powered relay control board designed for home automation and industrial switching applications. It features four independently controllable relay channels driven by an ESP32-C3 SuperMini, enabling Wi-Fi and Bluetooth control without an external power adapter.

Attribute	Value
Version	0.2.0
EDA Tool	KiCad 8
PCB Layers	2 (F.Cu / B.Cu)
Board Outline	See `pcb/pcb.kicad_pcb`
3D Model	`pcb/UTAC_PCB.step`

Features

4 relay channels — SPDT 5 V relays (SRA-05VDC-CL), rated for mains-level switching
ESP32-C3 SuperMini — Wi-Fi 4 (802.11 b/g/n) + Bluetooth 5 LE MCU
Onboard AC–DC supply — Hi-Link HLK-10M05 module (100–240 V AC → 5 V / 2 A DC)
Boost converter — LM2577T-ADJ provides an adjustable higher-voltage rail
NPN relay drivers — MMBT2222A transistors with flyback diode protection (MRA4003T3G)
Status LEDs — one per relay channel for visual feedback
Screw terminals — load connections on J1, J11–J14 (3-pin) and J2 (4-pin)
Expansion headers — J4/J5/J6 (5-pin sockets) and J15 (2-pin socket)

Hardware Block Diagram

text

  AC Mains
     │
     ▼
 HLK-10M05          ┌──────────────────┐
 (AC → 5V)  ──5V──► │  ESP32-C3        │
     │               │  SuperMini (U1)  │
     │               └──────┬───────────┘
     │                      │ GPIO x4
     │               ┌──────▼───────────┐
     ├──5V──────────►│ MMBT2222A (Q1-Q4)│  ← NPN drivers
     │               └──────┬───────────┘
     │                      │
     │               ┌──────▼───────────┐
     └──5V──────────►│ SRA-05VDC-CL     │  ← 4× SPDT Relay
                     │ Relays (K1-K4)   │
                     └──────┬───────────┘
                            │
                     Screw Terminals (Load)

  5V ──► LM2577T-ADJ (U2) ──► Boost Rail (adjustable)

Bill of Materials

Reference	Qty	Value / Part
U1	1	ESP32-C3 SuperMini TH
U2	1	LM2577T-ADJ NOPB (boost converter)
PS1	1	HLK-10M05 (AC–DC module)
K1–K4	4	SRA-05VDC-CL (5 V relay)
Q1–Q4	4	MMBT2222A (NPN transistor)
D1–D4	4	MRA4003T3G (flyback diode)
D5	1	1N5821 (Schottky diode)
LED1–LED4	4	LED (status)
L1	1	100 µH
C1	1	100 nF
C2–C5	4	10 nF
C6	1	100 nF
C7	1	330 nF
C8	1	680 µF
R1, R5, R9, R13	4	1 kΩ
R2, R3, R6, R7, R10, R11, R14, R15	8	10 kΩ
R4, R8, R12, R16	4	100 Ω
R17	1	17.4 kΩ
R18	1	2 kΩ
R19	1	2.2 kΩ
J1, J11–J14	5	Screw Terminal 3-pin
J2	1	Screw Terminal 4-pin
J3	1	Pin header 1-pin
J4, J5, J6	3	Socket 5-pin
J15	1	Socket 2-pin

Full BOM CSV: pcb/pcb.csv

Repository Structure

text

UTAC-PCB/
├── README.md
├── .gitignore
└── pcb/                        # KiCad project root
    ├── pcb.kicad_pro           # KiCad project file
    ├── pcb.kicad_pcb           # PCB layout
    ├── pcb.kicad_sch           # Schematic
    ├── pcb.rules               # Custom DRC rules
    ├── pcb.dsn                 # Specctra DSN (autorouter export)
    ├── pcb.csv                 # Bill of Materials
    ├── UTAC_PCB.step           # 3D model (STEP)
    └── Gerber/                 # Fabrication outputs
        ├── pcb-F_Cu.gbr        # Front copper
        ├── pcb-B_Cu.gbr        # Back copper
        ├── pcb-F_Mask.gbr      # Front solder mask
        ├── pcb-B_Mask.gbr      # Back solder mask
        ├── pcb-F_Silkscreen.gbr
        ├── pcb-B_Silkscreen.gbr
        ├── pcb-Edge_Cuts.gbr   # Board outline
        ├── pcb-PTH.drl         # Plated through-holes drill
        ├── pcb-NPTH.drl        # Non-plated through-holes drill
        ├── pcb-job.gbrjob      # Gerber job file
        └── Gerber.zip          # All Gerber files packaged

Getting Started

Opening in KiCad

Install KiCad 8 or later.

Clone this repository:

bash

git clone https://github.com/X-zeed/UTAC-PCB.git

Open pcb/pcb.kicad_pro in KiCad.

PCB Fabrication

Send the pcb/Gerber/Gerber.zip file directly to your PCB manufacturer (JLCPCB, PCBWay, OSHPark, etc.).

Recommended fab specs:

Parameter	Value
Layers	2
Surface finish	HASL or ENIG
Min trace / space	0.2 mm / 0.2 mm
Min drill	0.8 mm

Safety Notice

WARNING — MAINS VOLTAGE This board connects directly to AC mains (100–240 V). Always ensure proper isolation, enclosure, and adherence to local electrical regulations before powering the board. Do not touch the board when mains is connected.

License

This hardware design is released under the CERN Open Hardware Licence Version 2 – Permissive (CERN-OHL-P v2).

Designed with KiCad · Wachirawit Tanleng · 2026

Category and platform

Home automation and IoT ESP32 RISC-V

Project files

Show this board on your page

https://pcbkit.io/boards/X-zeed/UTAC-PCB

The board's own page, for a message or a post.

Source

Repository: X-zeed/UTAC-PCB
Board file: pcb/pcb.kicad_pcb
Commit: a6dd0a0
Licence: Not stated

Parts

Qty	Value	Footprint	References
8	10K	Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal	R2, R3, R6, R7, R10, R11, R14, R15
5	Screw_Terminal_01x03	Connector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_Vertical	J1, J11, J12, J13, J14
4	100	Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal	R4, R8, R12, R16
4	10n	Capacitor_THT:C_Disc_D3.0mm_W1.6mm_P2.50mm	C2, C3, C4, C5
4	1K	Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal	R1, R5, R9, R13
4	LED	LED_THT:LED_D3.0mm	LED1, LED2, LED3, LED4
4	MMBT2222A	Package_TO_SOT_THT:TO-92_Inline	Q1, Q2, Q3, Q4
4	MRA4003T3G	Diode_THT:D_DO-41_SOD81_P10.16mm_Horizontal	D1, D2, D3, D4
4	SRA-05VDC-CL	RELAY_SRA-05VDC:RELAY_SRA-05VDC-CL	K1, K2, K3, K4
3	Conn_01x05_Socket	Connector_PinHeader_2.54mm:PinHeader_1x05_P2.54mm_Vertical	J4, J5, J6
1	0.1u	Capacitor_THT:C_Disc_D3.0mm_W1.6mm_P2.50mm	C6
1	0.33u	Capacitor_THT:C_Disc_D3.0mm_W1.6mm_P2.50mm	C7
1	100n	Capacitor_THT:C_Disc_D3.0mm_W1.6mm_P2.50mm	C1
1	100uH	Inductor_THT:L_Radial_D10.0mm_P5.00mm_Fastron_07M	L1
1	17.4k	Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal	R17
1	1N5821	Diode_THT:D_DO-201AD_P15.24mm_Horizontal	D5
1	2.2k	Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal	R19
1	2k	Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal	R18
1	680u	Capacitor_THT:CP_Radial_D10.0mm_P2.50mm	C8
1	Conn_01x01_Pin	Connector_PinHeader_2.54mm:PinHeader_1x01_P2.54mm_Vertical	J3
1	Conn_01x02_Socket	Connector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_Vertical	J15
1	ESP32-C3_SUPERMINI_TH	ESP32_SuperMini:MODULE_ESP32-C3_SUPERMINI_TH	U1
1	HLK-10M05	Converter_ACDC:Converter_ACDC_Hi-Link_HLK-10Mxx	PS1
1	LM2577T-ADJ_NOPB	LM2577T-ADJ_NOPB:VREG_LM2577T-ADJ_NOPB	U2
1	Screw_Terminal_01x04	Connector_PinHeader_2.54mm:PinHeader_1x04_P2.54mm_Vertical	J2

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Questions

How big is the UTAC PCB PCB?

It measures 104 × 60 mm and has 2 copper layers, 1.6 mm thick.

What parts does the UTAC PCB use?

59 parts, built around the HLK-10M05, MMBT2222A, MRA4003T3G-MS and SRA-05VDC-CL. 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 UTAC PCB KiCad files?

From the X-zeed/UTAC-PCB repository on GitHub, at the commit this page was made from: the board is pcb/pcb.kicad_pcb and its schematic pcb/pcb.kicad_sch. PCBKit opens the board in the browser, with nothing to install.

Can I use the UTAC PCB design in my own project?

Its repository states no licence, so its author keeps all rights: ask X-zeed before reusing the design.