⚡ Relay Control Circuit via I2C (24V Power Supply) ⚡

📜 Schematic

📷 Circuit Diagram:

🖼️ PCB Images

🔻 Bottom Layer

🔺 Top Layer

🎥 3D View

🛠️ Introduction

This circuit operates on a 24V power supply and can control relays via I2C communication. The key components include:

• 🔹 MCP23017: GPIO expander with I2C interface.
• 🔹 ULN2803A: Darlington transistor driver for relay activation.
• 🔹 VOM617A-2T: Optocoupler for signal isolation.
• 🔹 Relay: Controls electrical loads by turning them on/off.
• 🔹 LM2596: Step-down module to convert 24V to 5V for powering the microcontroller and MCP23017.
• 🔹 RJ45: Used for remote control signal connections.

📋 Circuit Diagram

• 🟢 Main 24V power supply for the entire system.
• 🟢 LM2596 steps down 24V to 5V to power MCP23017, ULN2803A, and the microcontroller.
• 🟢 MCP23017 expands GPIO ports to control multiple relays.
• 🟢 ULN2803A amplifies current from MCP23017 to drive relays.
• 🟢 Optocoupler VOM617A-2T isolates the control signal from the power circuit.
• 🟢 RJ45 enables remote transmission of I2C signals or other control signals.
• 🟢 24V relay is activated to switch high-power loads.

⚡ Features

✅ Relay ON/OFF control via I2C-compatible microcontroller.
✅ Electrical isolation between control signals and high-voltage loads.
✅ Supports multiple relay expansion with MCP23017.
✅ Uses LM2596 to step down 24V to 5V, eliminating the need for an additional power circuit.
✅ Remote control signal transmission via RJ45.

🔌 Usage Guide

1️⃣ Hardware Connections

🔋 Input power: 24V for relay and LM2596
⚡ LM2596: Converts 24V to 5V for the control IC
🔗 SDA, SCL of MCP23017 → Microcontroller (ESP32, Raspberry Pi, Arduino...)
🖲️ OUTPUT of MCP23017 → INPUT of ULN2803A
🔌 OUTPUT of ULN2803A → 24V Relay
🛡️ Optocoupler (VOM617A-2T) → Isolates control signal
🌐 RJ45 → Connects the circuit to a remote control system