How to Use 12V 8-Channel Relay Module: Examples, Pinouts, and Specs

The 12V 8-Channel Relay Module (Manufacturer: Hong Wei, Part ID: JQC3F-12VDC-C) is a versatile electronic component designed to control multiple high-power devices using low-voltage signals. This module features 8 independent relays, each capable of switching high-voltage loads, making it ideal for home automation, industrial control systems, and robotics.

• Home automation (e.g., controlling lights, fans, or appliances)
• Industrial equipment control
• Robotics and mechatronics
• IoT (Internet of Things) projects
• Signal isolation between low-power microcontrollers and high-power devices

• Control Side: Connect the microcontroller's GPIO pins to IN1-IN8, and provide 5V to VCC and GND.
• Power Side: Connect a 12V DC power supply to JD-VCC and GND. Ensure proper isolation between the control and power sides.

1. Power the Module:
   • Connect a 12V DC power supply to the JD-VCC pin for the relay coils.
   • Connect the ground of the power supply to the module's GND pin.
2. Connect the Control Circuit:
   • Provide 5V DC to the VCC pin for the control circuit.
   • Connect the GND pin of the module to the ground of your microcontroller.
   • Use GPIO pins from your microcontroller to control the IN1-IN8 pins.
3. Connect the Load:
   • For each relay, connect the load's live wire to the COM terminal.
   • Use the NO terminal for devices that should be OFF by default or the NC terminal for devices that should be ON by default.
4. Control the Relays:
   • Send a HIGH signal (5V) to the desired INx pin to activate the corresponding relay.

• Isolation: Ensure proper electrical isolation between the control and power sides to prevent damage to the microcontroller.
• Current Ratings: Do not exceed the maximum current and voltage ratings of the relays.
• Flyback Diodes: If controlling inductive loads (e.g., motors), use flyback diodes to protect the relays from voltage spikes.
• Power Supply: Use a stable 12V DC power supply with sufficient current capacity to power all 8 relays simultaneously.

// Example code to control an 8-channel relay module with an Arduino UNO
// Ensure the relay module's VCC and GND are connected to the Arduino's 5V and GND pins.

#define RELAY1 2  // Define pin 2 for relay 1
#define RELAY2 3  // Define pin 3 for relay 2
#define RELAY3 4  // Define pin 4 for relay 3
#define RELAY4 5  // Define pin 5 for relay 4
#define RELAY5 6  // Define pin 6 for relay 5
#define RELAY6 7  // Define pin 7 for relay 6
#define RELAY7 8  // Define pin 8 for relay 7
#define RELAY8 9  // Define pin 9 for relay 8

void setup() {
  // Set all relay pins as OUTPUT
  pinMode(RELAY1, OUTPUT);
  pinMode(RELAY2, OUTPUT);
  pinMode(RELAY3, OUTPUT);
  pinMode(RELAY4, OUTPUT);
  pinMode(RELAY5, OUTPUT);
  pinMode(RELAY6, OUTPUT);
  pinMode(RELAY7, OUTPUT);
  pinMode(RELAY8, OUTPUT);

  // Initialize all relays to OFF state
  digitalWrite(RELAY1, LOW);
  digitalWrite(RELAY2, LOW);
  digitalWrite(RELAY3, LOW);
  digitalWrite(RELAY4, LOW);
  digitalWrite(RELAY5, LOW);
  digitalWrite(RELAY6, LOW);
  digitalWrite(RELAY7, LOW);
  digitalWrite(RELAY8, LOW);
}

void loop() {
  // Example: Turn relays ON and OFF sequentially
  digitalWrite(RELAY1, HIGH);  // Turn ON relay 1
  delay(1000);                 // Wait for 1 second
  digitalWrite(RELAY1, LOW);   // Turn OFF relay 1
  delay(1000);                 // Wait for 1 second

  // Repeat for other relays
  digitalWrite(RELAY2, HIGH);
  delay(1000);
  digitalWrite(RELAY2, LOW);
  delay(1000);

  // Add similar code for RELAY3 to RELAY8 as needed
}

1. Relays Not Activating:

   • Ensure the JD-VCC pin is connected to a 12V DC power supply.
   • Verify that the INx pins are receiving a HIGH signal (5V).
   • Check for loose or incorrect wiring.

2. Microcontroller Resetting:

   • This may occur if the relays draw too much current. Use a separate power supply for the relay module.

3. Load Not Switching:

   • Verify the wiring of the load to the COM, NO, and NC terminals.
   • Ensure the load's voltage and current are within the relay's rated limits.

Q: Can I use a 5V power supply for the relay coils?
A: No, the relay coils require a 12V DC power supply. The control circuit, however, operates at 5V.

Q: Can this module be used with a Raspberry Pi?
A: Yes, but you may need level shifters if the Raspberry Pi's GPIO pins output 3.3V instead of 5V.

Q: How many relays can I activate simultaneously?
A: All 8 relays can be activated simultaneously, provided your 12V power supply can handle the total current draw.

Q: Is the module safe for high-voltage applications?
A: Yes, but ensure proper insulation and follow safety guidelines when working with high voltages.