Control Devices with a Relay Module

Required Components

• Arduino board (e.g., Uno, Nano)
• Relay module (1-channel or more)
• High-voltage device (e.g., lamp, fan, or appliance)
• Jumper wires
• Breadboard (optional)
• Power supply for the high-voltage device

Wiring Instructions

Follow these steps to connect the relay module to the Arduino and the high-voltage device:

• Connect the VCC pin of the relay module to the 5V pin on the Arduino.
• Connect the GND pin of the relay module to the GND pin on the Arduino.
• Connect the IN pin (control pin) of the relay module to a digital pin on the Arduino (e.g., pin 7).
• For the high-voltage device:
  • Connect one terminal to the normally open (NO) terminal of the relay.
  • Connect the other terminal to the AC power supply.
  • Connect the common (COM) terminal of the relay to the AC power supply as well.

Code Explanation

The Arduino code controls the relay using digital signals:

• The relay is connected to a digital pin (e.g., pin 7).
• A HIGH signal from the Arduino closes the relay, allowing current to flow through the high-voltage device.
• A LOW signal opens the relay, cutting off the current and turning off the device.
• The delay() function creates a simple timer to toggle the relay on and off.

Arduino Code

const int relayPin = 7; // Pin connected to the relay module

void setup() {
    pinMode(relayPin, OUTPUT); // Set relay pin as an output
    digitalWrite(relayPin, LOW); // Initialize relay as OFF
}

void loop() {
    digitalWrite(relayPin, HIGH); // Turn the relay ON (device ON)
    delay(5000); // Keep it ON for 5 seconds
    digitalWrite(relayPin, LOW); // Turn the relay OFF (device OFF)
    delay(5000); // Keep it OFF for 5 seconds
}
        

Upload and Test

1. Assemble the circuit according to the wiring instructions.
2. Connect your Arduino to your computer via USB.
3. Upload the provided code using the Arduino IDE.
4. Observe the high-voltage device turning ON and OFF in 5-second intervals.

How It Works

The relay acts as an electrically operated switch:

• When the Arduino sends a HIGH signal to the relay, it closes the circuit, allowing current to flow through the high-voltage device.
• When the signal is LOW, the relay opens the circuit, cutting off current and turning the device OFF.
• This isolation ensures the Arduino handles only low voltage, keeping the high-voltage circuitry separate and safe.

Safety Precautions

Working with high-voltage devices requires caution:

• Ensure the relay is rated for the voltage and current of your device.
• Use insulated tools and wires to avoid accidental shocks.
• Never touch live wires or connections.
• Use a case or enclosure to protect the relay and connections.

Applications

Here are some practical uses for this project:

• Home automation to control lights or fans.
• Industrial automation for machines or appliances.
• Temperature or motion-triggered systems using additional sensors.

Troubleshooting

If the project doesn't work as expected, check the following:

• Ensure the relay module is receiving power and connected properly.
• Verify the control pin connection between the Arduino and the relay.
• Double-check your wiring for loose connections.
• Test the high-voltage device with a manual switch to ensure it works.

Conclusion

This project demonstrates how to safely control high-voltage devices using an Arduino and a relay module. By expanding the code and setup, you can create automated and remotely controlled systems for various applications.