This project guides you through building a Bluetooth-controlled room light switch using an Arduino Uno and an HC-05 Bluetooth module. This allows you to wirelessly toggle your room light ON and OFF using a smartphone application.
Components Required
- Arduino Uno Board: The microcontroller that executes the program logic.
- HC-05 Bluetooth Module: The wireless communication device that receives commands from the smartphone.
- 5V Relay Module: An electronic switch that isolates the low-voltage Arduino circuit from the high-voltage AC light circuit.
- Light Bulb, Bulb Holder, and Plug: The high-voltage load being controlled.
Phase 1: Wiring the Components
The connection involves linking the Bluetooth module and the Relay module to the Arduino board:
| Component Pin | Arduino Pin |
| HC-05 VCC | 5V Supply Pin |
| HC-05 GND | GND Pin |
| HC-05 TX (Transmit Data) | RX Pin (Receive Data) |
| HC-05 RX (Receive Data) | TX Pin (Transmit Data) |
| Relay IN1 | Digital Pin D8 |
How It Works
This fun and useful project lets you control your room light using your smartphone and Bluetooth — no need to get up or fumble with switches!
- You use an Arduino Uno as the brain of the system. It listens for commands sent over Bluetooth from your phone.
- The HC-05 Bluetooth module acts like a wireless bridge, receiving your phone’s signals and telling the Arduino what to do.
- The 5V relay module acts as a sturdy electronic switch that can turn your light bulb ON or OFF safely, even though the Arduino works on low voltage and the light bulb usually runs on high voltage.
- The light bulb and holder are the part you want to control in your room, like your regular ceiling or desk light.
Watch the full video tutorial here: How to make a Room light control with Mobile Bluetooth and Arduino at home | step by step process