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 interface between low-power control systems (e.g., microcontrollers like Arduino) and high-power devices such as lights, motors, or appliances. This module is widely used in home automation, industrial control systems, and robotics to enable remote control and automation of devices.

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

• Operating Voltage: 5V DC
• Trigger Voltage: 3.3V to 5V (compatible with most microcontrollers)
• Relay Type: Electromechanical
• Relay Channels: 4
• Maximum Load (per channel):
  • AC: 250V at 10A
  • DC: 30V at 10A
• Isolation: Optocoupler isolation for signal protection
• Dimensions: Approximately 75mm x 55mm x 20mm
• Indicator LEDs: One LED per channel to indicate relay status
• Control Logic: Active low (relay is triggered when input pin is LOW)

Each relay channel has three output terminals:

1. Power the Module:

   • Connect the VCC pin to a 5V DC power source and the GND pin to ground.
   • Ensure the power supply can provide sufficient current for all four relays (approximately 70-80mA per active relay).

2. Connect the Control Signals:

   • Connect the IN1, IN2, IN3, and IN4 pins to the digital output pins of a microcontroller (e.g., Arduino).
   • Use a common ground between the relay module and the microcontroller.

3. Connect the Load:

   • For each relay channel, connect the load to the COM, NO, or NC terminals based on your requirements:
     • Use COM and NO for devices that should turn ON when the relay is active.
     • Use COM and NC for devices that should turn OFF when the relay is active.

4. Control the Relays:

   • Send a LOW signal to the corresponding input pin (IN1, IN2, etc.) to activate the relay.
   • Send a HIGH signal to deactivate the relay.

• 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 at 250V AC or 30V DC) to prevent damage.
• Inductive Loads: For inductive loads (e.g., motors), use a flyback diode across the load to suppress voltage spikes.
• Power Supply: Use a stable 5V power supply to avoid relay malfunction.

// Example code to control a 4-channel relay module with 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 sequence to toggle relays
  digitalWrite(RELAY1, LOW); // Turn ON Relay 1
  delay(1000);               // Wait for 1 second
  digitalWrite(RELAY1, HIGH); // Turn OFF Relay 1
  delay(1000);               // Wait for 1 second

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

  // Repeat for RELAY3 and RELAY4 as needed
}

1. Relays Not Activating:

   • Cause: Insufficient power supply.
   • Solution: Ensure the power supply provides 5V and sufficient current for all active relays.

2. Microcontroller Resetting When Relays Activate:

   • Cause: Voltage spikes or insufficient power supply.
   • Solution: Use a separate power supply for the relay module or add a capacitor across the power lines.

3. Load Not Turning ON/OFF:

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

4. Indicator LEDs Not Lighting Up:

   • Cause: Faulty module or incorrect control signals.
   • Solution: Check the control signals with a multimeter and ensure they are active LOW.

Q1: Can I use this module with a 3.3V microcontroller like ESP32?
A1: Yes, the module is compatible with 3.3V control signals, but ensure the VCC pin is powered with 5V.

Q2: Can I control AC and DC loads simultaneously?
A2: Yes, each relay channel is independent, so you can control AC and DC loads on different channels.

Q3: How do I protect the relays from damage when controlling motors?
A3: Use a flyback diode across the motor terminals to suppress voltage spikes caused by inductive loads.