How to Use Relay 2 channel: Examples, Pinouts, and Specs

The Relay 2 Channel module is an electronic component designed to control high-voltage devices using low-voltage signals. It features two independent relays, allowing users to switch two separate circuits. Each relay is opto-isolated, ensuring safety and protecting the low-voltage control side from potential high-voltage spikes. This module is widely used in home automation, industrial control systems, and remote control applications.

Common applications include:

• Controlling lights, fans, or other household appliances.
• Automating industrial equipment.
• Interfacing with microcontrollers like Arduino or Raspberry Pi for IoT projects.

The Relay 2 Channel module has the following key specifications:

The module has two sets of pins: control pins and relay output terminals.

1. Power the Module: Connect the VCC pin to a 5V DC power source and the GND pin to ground.
2. Connect the Control Signals: Use a microcontroller (e.g., Arduino) or other control device to send signals to the IN1 and IN2 pins. A LOW signal (0V) will activate the corresponding relay.
3. Connect the Load:
   • For each relay, connect the device you want to control to the COM terminal.
   • Choose either the NO (Normally Open) or NC (Normally Closed) terminal based on your application:
     • 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. Test the Circuit: Once everything is connected, send control signals to the IN1 and IN2 pins to toggle the relays and control the connected devices.

• Isolation: Ensure proper isolation between the high-voltage and low-voltage sides to prevent damage or hazards.
• Power Supply: Use a stable 5V DC power source to avoid erratic relay behavior.
• Load Ratings: Do not exceed the maximum load ratings (250V AC @ 10A or 30V DC @ 10A) to prevent damage to the relays.
• Active LOW Trigger: Remember that the relays are triggered by a LOW signal (0V). Sending a HIGH signal (5V) will deactivate the relay.

Below is an example code to control the Relay 2 Channel module using an Arduino UNO:

// Define the control pins for the relays
const int relay1Pin = 7; // Pin connected to IN1
const int relay2Pin = 8; // Pin connected to IN2

void setup() {
  // Set the relay pins as outputs
  pinMode(relay1Pin, OUTPUT);
  pinMode(relay2Pin, OUTPUT);

  // Initialize relays to OFF state (HIGH signal)
  digitalWrite(relay1Pin, HIGH);
  digitalWrite(relay2Pin, HIGH);
}

void loop() {
  // Turn Relay 1 ON (LOW signal)
  digitalWrite(relay1Pin, LOW);
  delay(1000); // Keep it ON for 1 second

  // Turn Relay 1 OFF (HIGH signal)
  digitalWrite(relay1Pin, HIGH);
  delay(1000); // Keep it OFF for 1 second

  // Turn Relay 2 ON (LOW signal)
  digitalWrite(relay2Pin, LOW);
  delay(1000); // Keep it ON for 1 second

  // Turn Relay 2 OFF (HIGH signal)
  digitalWrite(relay2Pin, HIGH);
  delay(1000); // Keep it OFF for 1 second
}

1. Relays Not Activating:

   • Cause: Insufficient power supply.

   • Solution: Ensure the VCC pin is connected to a stable 5V DC source.

   • Cause: Incorrect control signal.

   • Solution: Verify that the IN1 and IN2 pins are receiving a LOW signal (0V) to activate the relays.

2. Erratic Relay Behavior:

   • Cause: Noise or interference in the power supply.
   • Solution: Use a decoupling capacitor (e.g., 100µF) across the VCC and GND pins.

3. Load Not Switching Properly:

   • Cause: Exceeding the relay's load ratings.
   • Solution: Ensure the connected load does not exceed 250V AC @ 10A or 30V DC @ 10A.

4. Microcontroller Resetting When Relay Activates:

   • Cause: Voltage spikes or back EMF from the relay.
   • Solution: Use a flyback diode across the relay coil or ensure proper grounding.

Q1: Can I use the Relay 2 Channel module with a 3.3V microcontroller?
A1: Yes, the module can be triggered with 3.3V signals, but ensure the VCC pin is still powered with 5V DC.

Q2: Is it safe to control high-voltage devices with this module?
A2: Yes, the module is designed for high-voltage control, but always follow safety precautions and ensure proper isolation.

Q3: Can I control both relays simultaneously?
A3: Yes, you can activate both relays at the same time by sending LOW signals to both IN1 and IN2 pins.

Q4: What happens if I connect the NO and NC terminals at the same time?
A4: This is not recommended as it may cause a short circuit or damage the relay. Always use either NO or NC, not both.