2 layers63 × 75 mm
2 layers74.5 × 63 mm
Relay board v2
slimmsehli/RelayBoardRelay Board for 250VAC/10VDC controlled by 5v
- Size
- 74.5 × 63 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 33
- Nets
- 38
- Pads
- 98
- Tracks, vias
- 146, 0
- Routed
- Yes
- KiCad
- KiCad 8.0 (file 20240108)
- Created
- 9 May 2025
- Updated
- 29 May 2025
Overview
Relay board v2 is an open-source printed circuit board by slimmsehli, from the slimmsehli/RelayBoard repository on GitHub. It is a 2-layer board of 74.5 × 63 mm with 33 parts on 38 nets, routed with 146 tracks and 0 vias.
It is built around the BC817. Its parts include 8 resistors, 8 diodes, 5 connectors, 4 ICs and 4 transistors. It belongs with the home automation and IoT boards of this library.
Main components
1README
README🟢 4-Channel Relay Board with Opto-Isolation for Arduino/Raspberry Pi
This project is a modular, 4-channel relay control board designed for microcontrollers like **Arduino, Raspberry Pi, ESP32, etc. The board features opto-isolation for electrical protection and safety, and is ideal for home automation, IoT, or industrial control applications.
📦 Features
- ✅ 4 independent relays (SPDT type) – control AC/DC loads up to 250V AC / 30V DC
- ✅ 4 opto-isolated inputs – control each relay with 3.3V or 5V logic
- ✅ Load-side isolation – added safety through PCB cutouts (drilled part under relay contacts)
- ✅ Status indicator LEDs – per-relay operation feedback
- ✅ Designed for Arduino, Raspberry Pi, ESP8266, ESP32, etc.
- ✅ Screw terminals for easy wiring of relays and power
⚙️ Technical Specs
| Feature | Description |
|---|---|
| Relay type | 5V SPDT |
| Input voltage | 5V logic compatible |
| Isolation | Optical + PCB drilled spacing |
| Max switching | 10A 250V AC / 10A 30V DC |
| Board size | 65mmx70mm |
| Control headers | 4-pin input control (IN1–IN4) |
| Load terminals | NO, COM, NC per relay |
📌 Pinout
| Pin | Description |
|---|---|
| IN1 | Control for Relay 1 |
| IN2 | Control for Relay 2 |
| IN3 | Control for Relay 3 |
| IN4 | Control for Relay 4 |
| VCC | Input side power (5V) |
| GND | Ground |
Each control input drives one relay via an optocoupler for full isolation.
Parts
33| Qty | Value | Footprint | References |
|---|---|---|---|
| 4 | 1K | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal | R1, R3, R5, R7 |
| 4 | 1N4007 | Diode_THT:D_DO-41_SOD81_P10.16mm_Horizontal | D1, D4, D6, D8 |
| 4 | 510R | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal | R2, R4, R6, R8 |
| 4 | BC817 | Package_TO_SOT_SMD:SOT-23 | Q1, Q2, Q3, Q4 |
| 4 | Conn_01x03_Pin | TerminalBlock:TerminalBlock_bornier-3_P5.08mm | J1, J2, J3, J4 |
| 4 | LED | LED_SMD:LED_1206_3216Metric_Pad1.42x1.75mm_HandSolder | D2, D3, D5, D7 |
| 4 | PC817 | Package_DIP:DIP-4_W7.62mm | U1, U2, U3, U4 |
| 4 | SANYOU_SRD_Form_C | Relay_THT:Relay_SPDT_SANYOU_SRD_Series_Form_C | K1, K2, K3, K4 |
| 1 | Conn_01x06_Pin | Connector_PinHeader_2.54mm:PinHeader_1x06_P2.54mm_Vertical | J5 |
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Questions
How big is the Relay board v2 PCB?
It measures 74.5 × 63 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Relay board v2 use?
33 parts, built around the BC817. 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 Relay board v2 KiCad files?
From the slimmsehli/RelayBoard repository on GitHub, at the commit this page was made from: the board is Relay_board_kiCad_v2/Relay_board_v2.kicad_pcb and its schematic Relay_board/Relay_board/Relay_board.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Relay board v2 design in my own project?
Its repository states no licence, so its author keeps all rights: ask slimmsehli before reusing the design.