5V 4-Channel Relay Module With Arduino

by Rachana Jain in Circuits > Arduino

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5V 4-Channel Relay Module With Arduino

Interfacing-5V-4-Channel-Relay-Module-with-Arduino-2.jpg

Relays are essential components in electronic projects that allow low-power microcontrollers like Arduino to control high-power devices such as lights, fans, and appliances. A 5V 4-Channel Relay Module is a widely used interface that enables switching multiple AC or DC loads with ease.

In this tutorial, we will explore how to interface a 5V 4-Channel Relay Module with an Arduino. We will cover the relay module’s pinout, working principle, internal circuitry, and specifications, followed by a practical example to control LED and motor using Arduino.

Supplies

Arduino UNO R31 Revision R3- Banggood

1 9V Battery Amazon

1 Half Size Bread board1 Banggood

1 multicolour LED Common cathode Amazon | Banggood

19V DC DC Motor Amazon

10 Jumper Wires Banggood

12V Supply Adapter Amazon

How Relays Work?

A relay is an electrically operated switch that allows a low-voltage signal to control a higher voltage or current load. Relays use an electromagnetic coil to mechanically switch contacts, isolating the control circuit from the load circuit. When current flows through the coil, it generates a magnetic field that pulls a metal contact, closing or opening the circuit. This makes relays ideal for controlling high-power devices like motors, lights, and appliances using microcontrollers like Arduino. The 5V four-channel relay module used in Arduino projects is an EMR type, which can handle up to 250V AC or 30V DC loads.

5V Four-Channel Relay Module Pinout

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A 5V four-channel relay module consists of multiple pins that enable communication with a microcontroller. The pinout is as follows:

Power and Control Pins

  1. VCC — Powers the module (5V input from Arduino or an external power source)
  2. GND — Ground connection
  3. IN1 — Control signal for Relay 1
  4. IN2 — Control signal for Relay 2
  5. IN3 — Control signal for Relay 3
  6. IN4 — Control signal for Relay 4

These input pins (IN1 to IN4) are active LOW, meaning that sending a LOW (0V) signal to any input pin activates the corresponding relay.

Relay Output Connections

Each of the four relays has a set of three terminals:

  1. COM (Common Terminal) — The common contact for the relay.
  2. NO (Normally Open Terminal) — When the relay is inactive, this terminal is disconnected from COM. When the relay is activated, it connects to COM, completing the circuit.
  3. NC (Normally Closed Terminal) — When the relay is inactive, this terminal remains connected to COM. When the relay is activated, it disconnects from COM.

To control an external device, you can use either the NO or NC terminal based on your application requirements.

Internal Circuit Diagram of 5V Four-Channel Relay Module

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The internal circuit of the relay module consists of the following key components:

  1. Microcontroller Interface — The IN1 to IN4 pins receive signals from the Arduino or other microcontrollers.
  2. Transistor Driver Circuit — Each relay is controlled by a transistor (e.g., NPN type) that acts as a switch, allowing the control signal to energize the relay coil.
  3. Flyback Diodes — These diodes prevent voltage spikes when the relay is turned off, protecting the transistor and microcontroller.
  4. Optocouplers — These components isolate the low-voltage Arduino circuit from the high-voltage relay circuit, improving safety and reducing electrical noise.
  5. Relay Coils and Contacts — The relays contain electromagnetic coils that switch the COM, NO, and NC terminals.

This design ensures reliable operation while minimizing potential damage to the microcontroller or power supply.

Four-Channel Relay Module Specifications

Below are the key specifications of the 5V four-channel relay module:

  1. Number of Channels: 4
  2. Supply voltage — 3.75V to 6V
  3. Trigger current at input pins– 5mA
  4. Current through coil when the relay is active — ~70mA (single), ~300mA (all four)
  5. Relay maximum current at output– 10A
  6. Relay maximum contact voltage at output– 250VAC, 30VDC
  7. LED Indicators: Yes (each relay has an LED to indicate its ON/OFF status)
  8. Dimensions: Varies by manufacturer, typically around 75mm x 55mm x 18mm

This module is widely used in home automation, industrial control, and smart electronics projects, allowing microcontrollers to safely control high-power electrical devices.

Interfacing Four-Channel Relay Module With Arduino

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Now let us learn how to interface 4-Channel Relay module with Arduino.

Here, we will control a motor and an RGB LED. First, the motor will turn ON, and then the LED will cycle through different colors as its red, blue, and green anodes are connected to the supply one by one. Finally, the motor will stop, and the LED will turn OFF.

Code for Interfacing Four-Channel Relay Module With Arduino

#define RELAY_ON 0
#define RELAY_OFF 1
#define MOTOR_PIN 2
#define RED_PIN 3
#define BLUE_PIN 4
#define GREEN_PIN 5
void setup() {
// set the all relay pins as output
pinMode(MOTOR_PIN, OUTPUT);
pinMode(RED_PIN, OUTPUT);
pinMode(BLUE_PIN, OUTPUT);
pinMode(GREEN_PIN, OUTPUT);
digitalWrite(MOTOR_PIN, RELAY_OFF);
digitalWrite(RED_PIN, RELAY_OFF);
digitalWrite(BLUE_PIN, RELAY_OFF);
digitalWrite(GREEN_PIN, RELAY_OFF);
}
void loop() {
// Turn MOTOR_PIN ON
digitalWrite(MOTOR_PIN, RELAY_ON);
delay(1000); // Delay of 1 sec
// Turn RED_PIN ON
digitalWrite(RED_PIN, RELAY_ON);
delay(1000); // Delay of 1 sec
// Turn BLUE_PIN ON
digitalWrite(RED_PIN, RELAY_OFF);
digitalWrite(BLUE_PIN, RELAY_ON);
delay(1000); // Delay of 1 sec
// Turn GREEN_PIN ON
digitalWrite(BLUE_PIN, RELAY_OFF);
digitalWrite(GREEN_PIN, RELAY_ON);
delay(1000); // Delay of 1 sec
delay(1000); // Delay of 1 sec
// Turn Off All Relays
digitalWrite(MOTOR_PIN, RELAY_OFF);
digitalWrite(RED_PIN, RELAY_OFF);
digitalWrite(BLUE_PIN, RELAY_OFF);
digitalWrite(GREEN_PIN, RELAY_OFF);
delay(1000); // Delay of 1 sec
delay(1000); // Delay of 1 sec
}


By understanding how relays work and how to use the 5V four-channel relay module, you can integrate it into various projects requiring high-voltage switching. For a complete guide on wiring and coding the relay module with Arduino, visit Interfacing 5V 4-Channel Relay Module with Arduino