How to Use Relay 4 channel: Examples, Pinouts, and Specs

The Relay 4 Channel module is an electronic component designed to control four independent circuits using low voltage signals. It acts as an electrically operated switch, allowing you to control high-power devices such as lights, fans, or appliances with a microcontroller or other low-power control systems. This module is widely used in home automation, industrial control systems, and IoT projects.

• Home automation (e.g., controlling lights, fans, or appliances)
• Industrial equipment control
• IoT projects for remote device management
• Robotics and automation systems
• Smart energy management systems

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

• Operating Voltage: 5V DC
• Trigger Voltage: 3.3V to 5V (compatible with most microcontrollers)
• Relay Type: Electromechanical
• Maximum Load (per channel):
  • AC: 250V at 10A
  • DC: 30V at 10A
• Isolation: Optocoupler isolation for signal protection
• Dimensions: Varies by manufacturer, typically ~75mm x 55mm x 20mm

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

Each relay has three output terminals: COM (Common), NO (Normally Open), and NC (Normally Closed).

1. Power the Module:
   • Connect the VCC pin to a 5V power supply and the GND pin to the ground of your microcontroller.
2. Connect Control Signals:
   • Connect the IN1, IN2, IN3, and IN4 pins to the digital output pins of your microcontroller.
   • Ensure the control signals are active LOW (sending a LOW signal activates the relay).
3. Connect the Load:
   • For each relay, connect the load to the COM and NO/NC terminals based on your requirements:
     • Use NO if you want the circuit to be OFF by default and ON when the relay is activated.
     • Use NC if you want the circuit to be ON by default and OFF when the relay is activated.
4. Write Control Code:
   • Use your microcontroller to send LOW signals to the IN pins to activate the relays.

• Power Supply: Ensure the module is powered with a stable 5V DC supply. Avoid exceeding the voltage rating.
• Isolation: The module uses optocouplers for isolation, but ensure proper grounding to avoid electrical noise.
• Load Ratings: Do not exceed the maximum load ratings (10A for AC or DC) to prevent damage to the relays.
• Inductive Loads: When controlling inductive loads (e.g., motors), use a flyback diode across the load to suppress voltage spikes.

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

// Define the 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 relays ON and OFF with a delay
  digitalWrite(RELAY1, LOW); // Activate Relay 1
  delay(1000);               // Wait for 1 second
  digitalWrite(RELAY1, HIGH); // Deactivate Relay 1
  delay(1000);               // Wait for 1 second

  digitalWrite(RELAY2, LOW); // Activate Relay 2
  delay(1000);               // Wait for 1 second
  digitalWrite(RELAY2, HIGH); // Deactivate Relay 2
  delay(1000);               // Wait for 1 second

  digitalWrite(RELAY3, LOW); // Activate Relay 3
  delay(1000);               // Wait for 1 second
  digitalWrite(RELAY3, HIGH); // Deactivate Relay 3
  delay(1000);               // Wait for 1 second

  digitalWrite(RELAY4, LOW); // Activate Relay 4
  delay(1000);               // Wait for 1 second
  digitalWrite(RELAY4, HIGH); // Deactivate Relay 4
  delay(1000);               // Wait for 1 second
}

1. Relays Not Activating:

   • Cause: Insufficient power supply or incorrect wiring.
   • Solution: Ensure the module is powered with a stable 5V DC supply and check all connections.

2. Microcontroller Resetting:

   • Cause: High current draw from the relays causing voltage drops.
   • Solution: Use a separate power supply for the relay module and connect the grounds.

3. Load Not Switching:

   • Cause: Incorrect wiring of the load to the relay terminals.
   • Solution: Verify the load is connected to the correct COM and NO/NC terminals.

4. Relay Clicking Noise:

   • Cause: Rapid switching or unstable control signals.
   • Solution: Check the control code and ensure proper signal timing.

Q1: Can I use the Relay 4 Channel module with a 3.3V microcontroller?
A1: Yes, the module is compatible with 3.3V control signals, but ensure the VCC pin is powered with 5V.

Q2: Can I control DC motors with this module?
A2: Yes, but for inductive loads like motors, use a flyback diode to protect the relay from voltage spikes.

Q3: How do I know if a relay is active?
A3: Most modules have an LED indicator for each relay that lights up when the relay is active.

Q4: Can I use this module to control 220V AC appliances?
A4: Yes, but ensure the load does not exceed 250V AC at 10A, and follow proper safety precautions.