ESP32-C3 SuperMini Based 3-Channel Relay Board for IoT Home Automation

Overview

This DIY project is a 3-channel relay module based on the ESP32-C3 SuperMini, perfect for controlling home appliances like lights, fans, or AC sockets over Wi-Fi using Tasmota firmware. It supports I2C sensors like DHT11 or BMP280, enabling environment-based smart switching.

🧩 Key Features

• ✅ 3 Relay Outputs (AC/DC load control)

• ✅ ESP32-C3 SuperMini with Wi-Fi & BLE

• ✅ Supports Tasmota firmware (web-based control + MQTT)

• ✅ Voice control via Alexa and Google Home

• ✅ Onboard 5V DC Regulator (supports 220V AC input via Hi-Link)

• ✅ I2C Expansion Header (connect sensors like DHT11, BH1750, BMP280)

• ✅ Power and Relay Status LEDs

• ✅ Compact and reliable PCB design

🔧 Hardware Used

⚙️ Schematic Design

The design includes:

• Transistor driver circuits for each relay

• Flyback diodes to protect against voltage spikes

• 7805 voltage regulator to step down from 9–12V to 5V

• Onboard Hi-Link 5V AC–DC module for direct AC input

• I2C breakout header to connect sensors like DHT11

🖥️ PCB Layout and 3D View

🟨 PCB Design (Top View)

🔵 3D Preview

A clean and compact board with:

• Isolated AC/relay side

• ESP32-C3 mounting

• Power indication

• Screw terminals for safe connection

🌐 Firmware: Tasmota

This board is 100% Tasmota compatible with the ESP32 build:

1. Flash Tasmota for ESP32-C3 using Tasmota Web Installer

2. Configure GPIOs in Tasmota:

   • Relay1 → GPIO10

   • Relay2 → GPIO3

   • Relay3 → GPIO21

   • I2C SDA → GPIO4

   • I2C SCL → GPIO5

3. Connect to Wi-Fi and control via MQTT, Alexa, or Google Assistant

🌡️ Add-ons via I2C

Easily connect sensors like:

• DHT11/DHT22 – temperature/humidity

• BH1750 – light intensity

• BMP280/BME280 – temperature/pressure

Connect them to the I2C header and configure in Tasmota.

💡 Use Cases

• Turn on/off lights, fans, water pumps

• Automate devices based on sensor data

• Monitor temperature and humidity

• Integrate with Home Assistant, Node-RED, or openHAB
  
  

  🛠️ Build Tips

  • Ensure proper isolation between AC and low-voltage sides

  • Use heat shrink on AC terminals for safety

  • Double-check Hi-Link input/output polarity

  • Always test with a multimeter before applying AC power

  GITHUB Repo For Code And Other Details 
  https://github.com/ElectroIoT/ESP32-C3-3chRelay