How to Use 2-Channel 12V Relay Module: Examples, Pinouts, and Specs

The 2-Channel 12V Relay Module is an electronic component designed to control two independent circuits using a 12V power supply. It acts as an interface between low-power control systems (e.g., microcontrollers like Arduino) and high-power devices, such as motors, lights, or appliances. This module enables the safe switching of high-voltage or high-current loads using low-voltage control signals.

• Home automation systems (e.g., controlling lights, fans, or appliances)
• Industrial automation for switching high-power devices
• Robotics and motor control
• IoT projects requiring high-voltage device control
• Security systems (e.g., activating alarms or locks)

• Operating Voltage (Control Side): 12V DC
• Relay Output Voltage: 250V AC (max) or 30V DC (max)
• Relay Output Current: 10A (max)
• Trigger Voltage (Input Signal): 3-12V DC (logic low trigger)
• Number of Channels: 2
• Isolation: Optocoupler isolation for safe operation
• Dimensions: ~50mm x 40mm x 20mm
• Indicator LEDs: Onboard LEDs for relay status indication

The 2-Channel 12V Relay Module has two main sections: the input (control) side and the output (load) side.

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

1. Power the Module:

   • Connect the VCC pin to a 12V DC power supply and the GND pin to the ground.
   • Ensure the power supply can provide sufficient current for the relays (typically ~70mA per relay).

2. Connect the Control Signals:

   • Connect the IN1 and IN2 pins to the control signals from a microcontroller (e.g., Arduino).
   • A logic LOW (0V) on IN1 or IN2 will activate the corresponding relay.

3. Connect the Load:

   • Identify whether the load should be connected to the NO or NC terminal based on the desired default state.
   • Connect the power source and load to the appropriate terminals (COM, NO, or NC).

4. Test the Circuit:

   • When the control signal is LOW, the relay will activate, switching the load between the COM and NO terminals.

• 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 (250V AC or 30V DC) or current (10A) ratings of the relays.
• Flyback Diodes: For inductive loads (e.g., motors), use flyback diodes across the load to protect the relay from voltage spikes.
• Power Supply: Use a stable 12V DC power supply to avoid relay malfunction.

Below is an example of how to control the 2-Channel 12V Relay Module using an Arduino UNO.

• Connect the module's VCC to the Arduino's 12V power supply.
• Connect the module's GND to the Arduino's GND.
• Connect IN1 to Arduino digital pin 7 and IN2 to Arduino digital pin 8.

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

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

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

void loop() {
  // Turn Relay 1 ON
  digitalWrite(relay1, LOW); // LOW signal activates the relay
  delay(2000); // Wait for 2 seconds

  // Turn Relay 1 OFF
  digitalWrite(relay1, HIGH); // HIGH signal deactivates the relay
  delay(2000); // Wait for 2 seconds

  // Turn Relay 2 ON
  digitalWrite(relay2, LOW);
  delay(2000);

  // Turn Relay 2 OFF
  digitalWrite(relay2, HIGH);
  delay(2000);
}

1. Relays Not Activating:

   • Ensure the module is powered with a stable 12V DC supply.
   • Verify that the control signals (IN1/IN2) are correctly connected and set to logic LOW.

2. Load Not Switching:

   • Check the wiring of the load to the COM, NO, and NC terminals.
   • Ensure the load does not exceed the relay's voltage or current ratings.

3. Relay Clicking Noise:

   • This may indicate an unstable power supply. Use a regulated 12V DC source.

4. Arduino Resetting When Relays Activate:

   • The relays may draw too much current, causing voltage drops. Use a separate 12V power supply for the relay module.

Q: Can I use a 5V power supply instead of 12V?
A: No, this module is designed specifically for 12V operation. Using a lower voltage may cause malfunction.

Q: Can I control AC and DC loads simultaneously?
A: Yes, as long as each load is connected to a separate relay and does not exceed the relay's ratings.

Q: Is it safe to use this module with high-voltage devices?
A: Yes, but ensure proper insulation and safety precautions when working with high voltages.