How to Use 4 Channel Relay : Examples, Pinouts, and Specs

Introduction

The 4 Channel Relay by JLC PCB (Manufacturer Part ID: UNIO) is an electromechanical switch designed to control four independent circuits using a single control signal. This versatile component is widely used in automation, home appliances, and industrial control systems. It allows low-power control signals, such as those from a microcontroller, to manage high-power devices like motors, lights, and heaters.

Explore Projects Built with 4 Channel Relay

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Arduino-Controlled Relay Switch with Pushbutton Activation

This circuit utilizes a 4-channel relay module controlled by an Arduino UNO, allowing for the switching of multiple devices based on input from several pushbuttons. Each pushbutton can activate a corresponding relay channel, which can be used to control various loads, while LEDs provide visual feedback for the relay states.

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Battery-Powered 4-Channel Relay Control with LED Indicators

This circuit consists of a 5V battery powering a 4-channel relay module, which controls four LEDs (red, yellow, green, and blue) through individual resistors. Each relay channel is activated by a corresponding SPST toggle switch, allowing manual control of the LEDs.

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Arduino UNO Controlled Smart Lighting System with Relay and Micro Switches

This circuit uses an Arduino UNO to control a 4-channel relay module, which in turn controls four bulbs. Each relay channel is connected to a bulb and can be toggled by corresponding micro switches, allowing for manual control of the bulbs.

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Wi-Fi Controlled Relay System with ESP32 and LED Indicators

This circuit is a control system using an ESP32 microcontroller to manage a 4-channel relay module, which in turn controls various loads. The relays are activated by rocker switches and provide visual feedback through LEDs, while power is supplied and regulated by an HLK-PM12 module and protected by a fuse and circuit breaker.

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Common Applications

• Home automation systems (e.g., controlling lights, fans, or appliances)
• Industrial equipment control
• Robotics and IoT projects
• Motor and actuator control
• Security systems (e.g., activating alarms or locks)

Technical Specifications

The following table outlines the key technical details of the 4 Channel Relay:

Pin Configuration and Descriptions

The 4 Channel Relay module has the following pin configuration:

Input Pins

Output Terminals (Relay Channels)

Each relay channel has three terminals: | Terminal | Description | |--------------|---------------------------------------------------| | NO (Normally Open) | Open circuit when the relay is inactive. Closes when activated. | | NC (Normally Closed) | Closed circuit when the relay is inactive. Opens when activated. | | COM (Common) | Common terminal for the relay switch. |

Usage Instructions

How to Use the 4 Channel Relay in a Circuit

1. Power the Relay Module: Connect the VCC pin to a 5V DC power source and the GND pin to the ground.
2. Connect Control Signals: Use a microcontroller (e.g., Arduino UNO) to send control signals to the IN1, IN2, IN3, and IN4 pins. A HIGH signal activates the corresponding relay.
3. Connect Load Devices: Attach the devices you want to control to the relay's output terminals (NO, NC, and COM) based on your desired switching configuration.
4. Ensure Safety: Use proper insulation and avoid exceeding the relay's voltage and current ratings.

Important Considerations

• Isolation: The module uses optocouplers to isolate the control circuit from the high-power load, ensuring safety.
• Power Supply: Ensure the power supply can provide sufficient current for the relay coils.
• Flyback Diodes: If controlling inductive loads (e.g., motors), use flyback diodes to protect the relay from voltage spikes.
• Avoid Overloading: Do not exceed the maximum load voltage (250V AC / 30V DC) or current (10A).

Example: Connecting to an Arduino UNO

Below is an example of how to control the 4 Channel Relay using an Arduino UNO:

// Example: Controlling a 4 Channel Relay with Arduino UNO
// Connect IN1, IN2, IN3, and IN4 to Arduino digital pins 2, 3, 4, and 5 respectively.

#define RELAY1 2  // Pin connected to IN1
#define RELAY2 3  // Pin connected to IN2
#define RELAY3 4  // Pin connected to IN3
#define RELAY4 5  // Pin connected to IN4

void setup() {
  // Set relay pins as outputs
  pinMode(RELAY1, OUTPUT);
  pinMode(RELAY2, OUTPUT);
  pinMode(RELAY3, OUTPUT);
  pinMode(RELAY4, OUTPUT);

  // Initialize all relays to OFF
  digitalWrite(RELAY1, LOW);
  digitalWrite(RELAY2, LOW);
  digitalWrite(RELAY3, LOW);
  digitalWrite(RELAY4, LOW);
}

void loop() {
  // Example sequence to toggle relays
  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

  digitalWrite(RELAY2, HIGH); // Turn ON Relay 2
  delay(1000);                // Wait for 1 second
  digitalWrite(RELAY2, LOW);  // Turn OFF Relay 2
  delay(1000);                // Wait for 1 second

  // Repeat for RELAY3 and RELAY4 as needed
}

Troubleshooting and FAQs

Common Issues and Solutions

1. Relays Not Activating

   • Cause: Insufficient power supply or incorrect wiring.
   • Solution: Ensure the VCC pin is connected to a stable 5V DC source and the GND pin is properly grounded.

2. Relay Clicking but Load Not Switching

   • Cause: Incorrect wiring of the load to the relay terminals.
   • Solution: Verify the load is connected to the correct NO, NC, and COM terminals.

3. Microcontroller Resetting When Relay Activates

   • Cause: Voltage spikes from inductive loads.
   • Solution: Add flyback diodes across the load to suppress voltage spikes.

4. Relays Always ON or OFF

   • Cause: Control signal voltage mismatch or damaged relay module.
   • Solution: Ensure the control signal voltage matches the relay's trigger voltage (3.3V to 5V). Replace the module if damaged.

FAQs

Q: Can I use the 4 Channel Relay with a 3.3V microcontroller?
A: Yes, the relay module supports trigger voltages as low as 3.3V, making it compatible with 3.3V microcontrollers like ESP32 or Raspberry Pi.

Q: Is the relay module safe for high-power applications?
A: Yes, but ensure the load does not exceed the maximum ratings (250V AC / 30V DC, 10A). Use proper insulation and safety precautions.

Q: Can I control DC motors with this relay?
A: Yes, but for inductive loads like motors, use flyback diodes to protect the relay from voltage spikes.

Q: How do I know if a relay is active?
A: The module typically includes an LED indicator for each relay channel that lights up when the relay is activated.