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 independent circuits using a single microcontroller or switch. Each relay on the module acts as an electrically operated switch, allowing low-power control signals to manage high-power devices. This makes the module ideal for applications such as home automation, industrial control systems, and robotics.

• Home automation (e.g., controlling lights, fans, or appliances)
• Industrial equipment control
• Robotics and motor control
• IoT (Internet of Things) projects
• Smart home systems

The 4 Channel Relay Module is designed to interface with microcontrollers like Arduino, Raspberry Pi, and other control systems. Below are its key technical details:

• Operating Voltage: 5V DC
• Trigger Voltage: 3.3V to 5V (compatible with most microcontrollers)
• Relay Type: SPDT (Single Pole Double Throw)
• Maximum Load (per relay):
  • AC: 250V at 10A
  • DC: 30V at 10A
• Isolation: Optocoupler isolation for safe operation
• Dimensions: ~75mm x 55mm x 20mm
• Weight: ~70g

The module has two main interfaces: the control pins and the relay output terminals.

Each relay has three output terminals:

1. Power the Module:

   • Connect the VCC pin to a 5V DC power source.
   • Connect the GND pin to the ground of your power source or microcontroller.

2. Connect the Control Signals:

   • Connect the IN1, IN2, IN3, and IN4 pins to the digital output pins of your microcontroller.
   • Ensure the microcontroller's ground is connected to the module's GND.

3. Connect the Load:

   • For each relay, connect the device you want to control to the COM and NO or NC terminals, depending on your desired behavior:
     • Use NO for devices that should be off by default.
     • Use NC for devices that should be on by default.

4. Control the Relays:

   • Send a LOW signal (0V) to the corresponding IN pin to activate the relay.
   • Send a HIGH signal (5V) to deactivate the relay.

• Power Supply: Ensure the module is powered with a stable 5V DC supply. Using a higher voltage may damage the module.
• Isolation: The module uses optocouplers for isolation, but always exercise caution when working with high voltages.
• Load Ratings: Do not exceed the maximum load ratings (250V AC/10A or 30V DC/10A) to avoid damage or hazards.
• Active Low Logic: The relays are triggered by a LOW signal. Ensure your microcontroller code accounts for this.

Below is an example of how to control the 4 Channel Relay Module using an Arduino UNO:

// Example: Controlling a 4 Channel Relay Module with Arduino UNO

// Define the relay control pins
#define RELAY1 2  // Relay 1 connected to digital pin 2
#define RELAY2 3  // Relay 2 connected to digital pin 3
#define RELAY3 4  // Relay 3 connected to digital pin 4
#define RELAY4 5  // Relay 4 connected to digital pin 5

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 sequence to toggle relays
  digitalWrite(RELAY1, LOW);  // Turn ON Relay 1
  delay(1000);                // Wait 1 second
  digitalWrite(RELAY1, HIGH); // Turn OFF Relay 1

  digitalWrite(RELAY2, LOW);  // Turn ON Relay 2
  delay(1000);                // Wait 1 second
  digitalWrite(RELAY2, HIGH); // Turn OFF Relay 2

  digitalWrite(RELAY3, LOW);  // Turn ON Relay 3
  delay(1000);                // Wait 1 second
  digitalWrite(RELAY3, HIGH); // Turn OFF Relay 3

  digitalWrite(RELAY4, LOW);  // Turn ON Relay 4
  delay(1000);                // Wait 1 second
  digitalWrite(RELAY4, HIGH); // Turn OFF Relay 4
}

1. Relays Not Activating:

   • Cause: Insufficient power supply.
   • Solution: Ensure the module is powered with a stable 5V DC source.

2. Microcontroller Not Triggering Relays:

   • Cause: Incorrect wiring or logic level mismatch.
   • Solution: Verify the control pins are connected properly and sending LOW signals to activate the relays.

3. Load Not Switching:

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

4. Relay Clicking Noise but No Load Switching:

   • Cause: Load exceeds the relay's maximum rating.
   • Solution: Ensure the load is within the specified voltage and current limits.

Q1: Can I use the module with a 3.3V microcontroller like ESP32?
A1: Yes, the module is compatible with 3.3V logic levels, but ensure the power supply to the module is 5V.

Q2: Can I control AC and DC loads simultaneously?
A2: Yes, as long as each relay's load does not exceed the specified ratings.

Q3: Is it safe to use the module for high-power devices?
A3: Yes, but always ensure proper insulation and follow safety guidelines when working with high voltages.