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

The 2-Channel Relay Module (GM002), manufactured by PCBCIBID, is an electromechanical switch designed to control two independent circuits. This module allows low-power control signals, such as those from a microcontroller, to switch high-power devices like motors, lights, or appliances. It provides electrical isolation between the control circuit and the load, ensuring safety and reliability.

• Home automation systems (e.g., controlling lights or fans)
• Industrial equipment control
• Motor and pump control
• IoT projects requiring high-power switching
• Robotics and automation

• Manufacturer: PCBCIBID
• Part ID: GM002
• Number of Channels: 2
• Operating Voltage: 5V DC
• Trigger Voltage: 3.3V to 5V (compatible with most microcontrollers)
• Maximum Load Voltage: 250V AC or 30V DC
• Maximum Load Current: 10A
• Relay Type: SPDT (Single Pole Double Throw)
• Isolation: Optocoupler-based isolation between control and load circuits
• Dimensions: 50mm x 40mm x 18mm

The 2-CH relay module has two sets of pins: control pins and load terminals.

1. Power the Module:

   • Connect the VCC pin to a 5V DC power supply.
   • Connect the GND pin to the ground of the power supply.

2. Connect the Control Signals:

   • Connect the IN1 and IN2 pins to the digital output pins of a microcontroller (e.g., Arduino UNO).
   • Ensure the control signals are within the 3.3V to 5V range.

3. Connect the Load:

   • Identify the load you want to control (e.g., a light bulb or motor).
   • Connect one terminal of the load to the COM terminal of the relay.
   • Connect the other terminal of the load to either the NO or NC terminal, depending on the desired default state:
     • Use NO if the load should be OFF by default.
     • Use NC if the load should be ON by default.

4. Control the Relay:

   • Send a HIGH signal (3.3V to 5V) to the IN1 or IN2 pin to activate the corresponding relay.
   • When the relay is activated, the COM terminal will connect to the NO terminal.

• Power Supply: Ensure the module is powered with a stable 5V DC supply.
• Load Ratings: Do not exceed the maximum load voltage (250V AC or 30V DC) or current (10A).
• Isolation: The module provides optocoupler-based isolation, but additional safety measures (e.g., fuses) are recommended for high-power applications.
• Inductive Loads: When switching inductive loads (e.g., motors), use a flyback diode across the load to prevent voltage spikes.
• Microcontroller Compatibility: The module is compatible with 3.3V and 5V logic levels, making it suitable for most microcontrollers, including Arduino, Raspberry Pi, and ESP32.

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

• Connect the VCC pin of the relay module to the 5V pin of the Arduino.
• Connect the GND pin of the relay module to the GND pin of the Arduino.
• Connect the IN1 and IN2 pins of the relay module to digital pins 7 and 8 of the Arduino, respectively.

// Define the control pins for the relays
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 the relay pins as outputs
  pinMode(relay1, OUTPUT);
  pinMode(relay2, OUTPUT);

  // Initialize both relays to OFF state
  digitalWrite(relay1, LOW); // Relay 1 OFF
  digitalWrite(relay2, LOW); // Relay 2 OFF
}

void loop() {
  // Turn Relay 1 ON and Relay 2 OFF
  digitalWrite(relay1, HIGH); // Relay 1 ON
  digitalWrite(relay2, LOW);  // Relay 2 OFF
  delay(2000); // Wait for 2 seconds

  // Turn Relay 1 OFF and Relay 2 ON
  digitalWrite(relay1, LOW);  // Relay 1 OFF
  digitalWrite(relay2, HIGH); // Relay 2 ON
  delay(2000); // Wait for 2 seconds
}

1. Relay Not Activating:

   • Cause: Insufficient control signal voltage.
   • Solution: Ensure the control signal is within the 3.3V to 5V range.

2. Load Not Switching:

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

3. Module Overheating:

   • Cause: Exceeding the maximum load current or voltage.
   • Solution: Ensure the load does not exceed 10A or 250V AC/30V DC.

4. Interference with Microcontroller:

   • Cause: Voltage spikes from inductive loads.
   • Solution: Use a flyback diode across the load to suppress voltage spikes.

• Q: Can I use this module with a 3.3V microcontroller like ESP32?
  A: Yes, the module is compatible with 3.3V logic levels.

• Q: Can I control DC motors with this relay?
  A: Yes, but ensure the motor's voltage and current are within the relay's ratings.

• Q: Is the module safe for high-power applications?
  A: Yes, but additional safety measures, such as fuses and proper insulation, are recommended.

• Q: Can I use both relays simultaneously?
  A: Yes, both relays can operate independently and simultaneously.

This concludes the documentation for the 2-CH Relay Module (GM002).