Arduino project · Smart doors and home · Easy
Bluetooth Home Switch (Two Relays)
Switch two relay-controlled loads from your phone with ON and OFF buttons.
What you will learn
- How to switch real loads from a phone
- How relays isolate mains from the Arduino
- Why you should test with a bulb or a 12 V lamp first
How it works
Phone buttons 1 and 2 set and clear relay 1. Buttons 3 and 4 do the same for relay 2. The green LED mirrors relay 1 so you can see it from a distance.
Try this next
- Add a third relay.
- Make a timer that turns the load off after 1 minute.
- Show relay state on an LCD.
The simulator program and explanation on this page are original. The idea follows a classic Arduino project that students have built for years.
Caution: single-phase mains (230 V AC). The wall socket, relay contacts and load in this circuit carry mains voltage, which can kill. Work only with an adult, with the plug out of the wall, switch the LIVE wire only, fit a fuse or MCB, join Earth to metal bodies, use a closed insulated box, and have an electrician check it before you power it. In the simulator everything is safe. In real life, test with a low-voltage lamp first.
Parts: sensors and actuators (tap to show or hide)
Try the inputs (virtual sensors)
Pins (you can change them)
| Part | Arduino pin (change it here) | How to wire it |
|---|
Every wire, one by one
Red rail = 5 V from the Arduino 5V pin. Black rail = GND. The coloured wires carry signals. Match the wire colours on the drawing to this list.
| # | Colour | From (part and leg) | To |
|---|
Steps run from top to bottom, then start again. While the simulation runs, the active step is highlighted in green.
Quantities come from the parts you added. The store links open a search for that item on Robu.in, Amazon.in and ThinkRobotics, so you always see what is in stock today. Check the model, voltage and price before you order.
| # | Item | Qty | Search term | Buy / compare |
|---|
The PDF has the circuit sketch, pin table, every wire, sequence, full code, the parts list with store links, do’s and don’ts for each part, and the safety notes. The project file lets you come back and keep editing.
In the real world
A room with a lamp and a fan
Each relay switches one appliance. Watch the lamp and the fan in the real room.
Tip: use the gold tab at the bottom of the circuit drawing to pull the real-world view up over the Arduino board. Your parts stay visible above it, so you can press a button and watch the real scene react.
- Relay 1 = the lamp
- Relay 2 = the fan