How to Use 2-channel relay module: Examples, Pinouts, and Specs

The 2-Channel Relay Module by Michael Faraday 1830 is a versatile electronic component designed to control two independent circuits using a single microcontroller or switch. Each relay on the module acts as an electrically operated switch, allowing you to control high-voltage devices (such as lights, fans, or appliances) safely and efficiently.

This module is ideal for applications where isolation between the control circuit and the high-power circuit is required. It is commonly used in home automation, industrial control systems, and IoT projects.

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

• 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: 50mm x 40mm x 18mm
• Weight: ~30g
• Indicator LEDs: One LED per relay to indicate activation status

The 2-channel relay module has two sets of pins: Input Pins for control signals and Relay Output Terminals for connecting the load.

Each relay has three output terminals: COM, NO, and NC.

1. Power the Module:

   • Connect the VCC pin to a 5V power source and the GND pin to ground.
   • Ensure the power supply can provide sufficient current for the relays (typically ~70mA per relay when active).

2. Connect the Control Signals:

   • Connect the IN1 and IN2 pins to the digital output pins of a microcontroller (e.g., Arduino UNO).
   • When the microcontroller sends a HIGH signal to IN1 or IN2, the corresponding relay will activate.

3. Connect the Load:

   • Identify whether the load should be connected to the NO (Normally Open) or NC (Normally Closed) terminal.
   • Connect the power source for the load to the COM terminal.
   • Connect the load to either the NO or NC terminal, depending on the desired default state.

4. Test the Circuit:

   • Power on the system and send control signals to the IN1 and IN2 pins to toggle the relays.
   • Verify that the connected loads are switching as expected.

• Isolation: The module uses optocouplers for isolation, but ensure proper grounding between the control and load circuits.
• Load Ratings: Do not exceed the maximum voltage or current ratings of the relays.
• Flyback Diodes: For inductive loads (e.g., motors), use flyback diodes to protect the relays from voltage spikes.
• Safety: Always disconnect power before wiring high-voltage loads to the relay module.

Below is an example of how to control the 2-channel relay module using an Arduino UNO:

• VCC → Arduino 5V
• GND → Arduino GND
• IN1 → Arduino Digital Pin 7
• IN2 → Arduino Digital Pin 8
• Connect a 220V AC lamp to Relay 1 (COM and NO terminals).

// Define the relay control pins
const int relay1 = 7; // Relay 1 control pin
const int relay2 = 8; // Relay 2 control pin

void setup() {
  // Set relay pins as outputs
  pinMode(relay1, OUTPUT);
  pinMode(relay2, OUTPUT);

  // Initialize relays to OFF state
  digitalWrite(relay1, LOW);
  digitalWrite(relay2, LOW);
}

void loop() {
  // Turn Relay 1 ON for 2 seconds
  digitalWrite(relay1, HIGH); // Activate Relay 1
  delay(2000);                // Wait for 2 seconds

  // Turn Relay 1 OFF
  digitalWrite(relay1, LOW);  // Deactivate Relay 1
  delay(1000);                // Wait for 1 second

  // Turn Relay 2 ON for 3 seconds
  digitalWrite(relay2, HIGH); // Activate Relay 2
  delay(3000);                // Wait for 3 seconds

  // Turn Relay 2 OFF
  digitalWrite(relay2, LOW);  // Deactivate Relay 2
  delay(1000);                // Wait for 1 second
}

1. Relays Not Activating:

   • Cause: Insufficient power supply or incorrect wiring.
   • Solution: Ensure the module is powered with 5V and the control signals are HIGH.

2. Load Not Switching:

   • Cause: Incorrect connection to the relay terminals.
   • Solution: Verify the load is connected to the correct terminals (COM, NO, or NC).

3. Microcontroller Resetting:

   • Cause: Relays drawing too much current, causing voltage drops.
   • Solution: Use an external power supply for the relay module.

4. Relay Clicking Noise:

   • Cause: Rapid switching of the control signal.
   • Solution: Add a delay in the control code to prevent rapid toggling.

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

• Q: Can I control DC motors with this module?
  A: Yes, but use flyback diodes to protect the relays from voltage spikes caused by the motors.

• Q: Is the module safe for high-voltage applications?
  A: Yes, but always follow proper safety precautions when working with high voltages.

This concludes the documentation for the 2-Channel Relay Module by Michael Faraday 1830.