Bluetooth-Controlled Smart Home AC Hub

80 viewsMarch 12, 2026

ArduinoBluetoothHome AutomationRelayAC PowerSafety

A wireless AC appliance switching hub using an Arduino Uno and Bluetooth (HC-05/06). Safely bridge the gap between low-voltage DC signals and high-voltage AC power to control lights, fans, or heaters from your smartphone via a serial terminal app.

Components & Supplies

×1Arduino Uno R3

×1HC-05 Bluetooth Module

×12-Channel Relay Module (5V)

×13S 18650 Li-ion Battery Pack

×1LM2596 Buck Converter

×1AC Plug & Socket Connector

Circuit Connections

Component	Pin		Pin	Component
Arduino	D10 (RX)	→	TX	HC-05
Arduino	D11 (TX)	→	RX	HC-05
Arduino	D7	→	IN1	Relay Module
Relay Module	COM	→	Live	AC Mains
Relay Module	NO	→	Live	Load (Bulb)

The Concept

This project transforms an Arduino into a Bluetooth-enabled switch for mains appliances. It uses the HC-05 module to receive serial data from a mobile app. When specific characters are received (e.g., '1' or '0'), the Arduino triggers a logic signal to a Relay module, physically closing or opening the high-voltage AC circuit.

Emphasis is placed on power isolation and rugged power delivery using a 3S Li-ion battery stepped down for the Arduino.

Safety First

CAUTION: Working with 220V/110V AC power is extremely dangerous. Ensure all connections are insulated, use a proper enclosure, and always disconnect from the wall before modifying the circuit. Grounding is mandatory for metal surfaces.

arduino— Bluetooth Relay Sketch

#include <SoftwareSerial.h>

SoftwareSerial BTSerial(10, 11); // RX, TX
const int relayPin = 7;

void setup() {
  pinMode(relayPin, OUTPUT);
  digitalWrite(relayPin, HIGH); // Relay is often Active LOW
  BTSerial.begin(9600);
  Serial.begin(9600);
}

void loop() {
  if (BTSerial.available()) {
    char data = BTSerial.read();
    if (data == '1') {
      digitalWrite(relayPin, LOW); // ON
      BTSerial.println("Light: ON");
    } else if (data == '0') {
      digitalWrite(relayPin, HIGH); // OFF
      BTSerial.println("Light: OFF");
    }
  }
}