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Advanced 4-Channel 5V Relay Module with Onboard LM2596 Power

This project is an advanced 4-channel relay module designed for home automation and IoT applications. Unlike standard relay boards, this design integrates an LM2596 buck converter for onboard 12V-to-5V power regulation, making it compact, efficient, and safe. It includes reverse polarity protection, ON/OFF jumper control, improved LED indicators, and optimized PCB track widths for handling up to 10A per relay channel.

Advanced 4-Channel 5V Relay Module with Onboard LM2596 Power
 
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Story

📝 Introduction

This project is an advanced 4-channel relay module designed for home automation and IoT applications.
Unlike standard relay boards, this design integrates an LM2596 buck converter for onboard 12V-to-5V power regulation, making it compact, efficient, and safe.

It includes reverse polarity protection, ON/OFF jumper control, improved LED indicators, and optimized PCB track widths for handling up to 10A per relay channel.


⚡ Features

  • 4 Independent Relays (SRD-05VDC-SL-C) – each rated 10A @ 250VAC / 30VDC
  • Onboard LM2596SX Buck Converter – accepts 12V DC input and outputs regulated 5V
  • ON/OFF Control Jumper (H1) – enable/disable relay board manually
  • Reverse Polarity Protection with SS14 Schottky diode
  • Flyback Diodes (1N4007) across relay coils
  • Indicator LEDs with optimized 680Ω resistors for better brightness
  • MMBT2222A NPN Transistor Drivers for reliable switching
  • Compact & Efficient PCB Layout with 3D preview
  • High-current tracks (4mm+) for relay outputs, safe for up to 10A

📐 Schematics

Relay Driver Section

Each relay is driven by a transistor with flyback diode, LED indicator, and input header.

Power Supply Section

LM2596-based buck converter powers the relays and logic from a 12V input.

 

🛠️ PCB Layout

  • Relay coil traces (5V): 0.8mm
  • Relay output traces (COM/NO/NC): 4mm (supports 10A)
  • Separate high-voltage (AC) and low-voltage (5V) sections

 

🎨 3D Board Preview

Visual representation of the final PCB design:

📦 Bill of Materials (BOM)

Component Value / Part No. Qty
Relay SRD-05VDC-SL-C 4
Driver Transistor MMBT2222ALT1G 4
Flyback Diode 1N4007 4
Indicator LED XL-3216SURC 4
LED Resistor 680Ω 4
Base Resistor 1kΩ 4
Buck Converter IC LM2596SX-5.0/NOPB 1
Inductor 33µH 1
Schottky Diode SS54 1
Reverse Protection SS14 1
Input Capacitor 680µF / 35V 1
Output Capacitor 220µF / 16V 1
Ceramic Capacitors 100nF 2
DC Jack 5.5mm × 2.1mm 1
Screw Terminals WJ128V-5.0 6

🔧 Applications

  • 🏠 Home Automation – fans, lights, appliances
  • ⚙️ Industrial Projects – pumps, motors, solenoids
  • 💡 IoT Devices – WiFi/ESP32/Arduino-based controllers
  • 🔋 DIY Electronics – safe switching between microcontroller and AC/DC loads

🚀 Conclusion

This 4-Channel Relay Module with onboard LM2596 regulator is a complete, safe, and compact solution for powering and controlling AC/DC devices with a single 12V input.

It’s perfect for Arduino, ESP8266, ESP32, Raspberry Pi, and other microcontrollers.


📂 Downloads


🌐 Author & Contact

👨‍💻 Designed by ElectroIoT
🔗 Website: https://electroiot.in
▶️ YouTube: ElectroIoT-IN
📸 Instagram: @electroiot_in
📧 Email: electroiot.in@gmail.com


 

Open Source Hardware for Makers – Share, Learn & Build Together!

 

 

Code
  • https://github.com/ElectroIoT/Advanced-4-Channel-5V-Relay-Module-with-Onboard-LM2596-Power-Supply
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Schematic and Layout
  • https://github.com/ElectroIoT/Advanced-4-Channel-5V-Relay-Module-with-Onboard-LM2596-Power-Supply
    View
CAD-Custom parts and enclosures
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Advanced 4-Channel 5V Relay Module with Onboard LM2596 Power

This project is an advanced 4-channel relay module designed for home automation and IoT applications. Unlike standard relay boards, this design integrates an LM2596 buck converter for onboard 12V-to-5V power regulation, making it compact, efficient, and safe. It includes reverse polarity protection, ON/OFF jumper control, improved LED indicators, and optimized PCB track widths for handling up to 10A per relay channel.

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