How to Use 4 Channel Relay Module: Examples, Pinouts, and Specs

The 4 Channel Relay Module is an electronic component designed to control up to four separate high-power devices using low-voltage control signals. It acts as an interface between microcontrollers (e.g., Arduino, Raspberry Pi) and high-voltage devices, enabling safe and efficient switching. The module typically features opto-isolation to protect the control circuit from high-voltage spikes, ensuring safety and reliability.

• Home Automation: Controlling lights, fans, and other household appliances.
• Industrial Control: Managing motors, pumps, and other industrial equipment.
• Robotics: Switching actuators or other high-power components.
• IoT Projects: Enabling remote control of devices via the internet.
• Prototyping: Testing and developing circuits that require high-power switching.

The following are the key technical details of the 4 Channel Relay Module:

The 4 Channel Relay Module has the following pin layout:

Each relay has three output terminals:

1. Power the Module: Connect the VCC pin to a 5V DC power source and the GND pin to ground.
2. Connect Control Signals: Use digital output pins from a microcontroller (e.g., Arduino) to connect to the IN1, IN2, IN3, and IN4 pins. Ensure the control signals are active low.
3. Connect the Load: For each relay, connect the high-power device to the NO, NC, and COM terminals as required:
   • For devices that should turn on when the relay is activated, use the NO and COM terminals.
   • For devices that should turn off when the relay is activated, use the NC and COM terminals.
4. Write Control Code: Program the microcontroller to send signals to the IN pins to activate or deactivate the relays.

• Power Supply: Ensure the module is powered with a stable 5V DC supply. Avoid exceeding the voltage rating.
• Isolation: Use opto-isolation to protect the microcontroller from high-voltage spikes.
• Load Ratings: Do not exceed the maximum load ratings (250V AC @ 10A or 30V DC @ 10A) to prevent damage.
• Active Low Logic: Remember that the relays are triggered by a LOW signal on the IN pins.
• Safety: Always disconnect power when wiring high-voltage devices to the relay module.

Below is an example code snippet to control the 4 Channel Relay Module using an Arduino UNO:

// Define relay control pins
#define RELAY1 2  // Pin connected to IN1
#define RELAY2 3  // Pin connected to IN2
#define RELAY3 4  // Pin connected to IN3
#define RELAY4 5  // Pin connected to IN4

void setup() {
  // Set relay pins as outputs
  pinMode(RELAY1, OUTPUT);
  pinMode(RELAY2, OUTPUT);
  pinMode(RELAY3, OUTPUT);
  pinMode(RELAY4, OUTPUT);

  // Initialize all relays to OFF (HIGH state)
  digitalWrite(RELAY1, HIGH);
  digitalWrite(RELAY2, HIGH);
  digitalWrite(RELAY3, HIGH);
  digitalWrite(RELAY4, HIGH);
}

void loop() {
  // Example: Turn on Relay 1 for 2 seconds, then turn it off
  digitalWrite(RELAY1, LOW);  // Activate Relay 1
  delay(2000);                // Wait for 2 seconds
  digitalWrite(RELAY1, HIGH); // Deactivate Relay 1
  delay(2000);                // Wait for 2 seconds

  // Repeat similar logic for other relays as needed
}

1. Relays Not Activating:

   • Cause: Insufficient power supply or incorrect wiring.
   • Solution: Ensure the module is powered with 5V DC and the GND is connected properly.

2. Microcontroller Resetting When Relays Activate:

   • Cause: Voltage spikes or insufficient power supply to the microcontroller.
   • Solution: Use a separate power supply for the relay module and microcontroller. Add a flyback diode across the relay coil if not already present.

3. LED Indicators Not Lighting Up:

   • Cause: Faulty module or incorrect control signals.
   • Solution: Verify the control signals are active low and check the module for damage.

4. Load Not Switching Properly:

   • Cause: Incorrect wiring of the load to the relay terminals.
   • Solution: Double-check the connections to the NO, NC, and COM terminals.

• Q: Can I use a 3.3V microcontroller with this module?
  A: Yes, the module is compatible with 3.3V control signals, but ensure the power supply to the module is 5V.

• Q: Can I control DC motors with this module?
  A: Yes, as long as the motor's voltage and current ratings are within the relay's specifications.

• Q: Is it safe to use this module with 220V AC appliances?
  A: Yes, but ensure proper insulation and follow safety precautions when working with high voltages.

• Q: Can I use fewer than 4 relays?
  A: Yes, you can use only the required number of relays and leave the unused channels unconnected.