Relay Module En

The Arduino relay module is an electronic switch that allows control of high-voltage devices through microcontrollers like Arduino.

It can open and close high-voltage circuits using low-voltage signals, making it useful for controlling household electrical appliances and industrial equipment.

Components

Relay Module : The relay module consists of one or more relays and the electronic circuits required to control them.

Control Pin : This is the pin that receives the signal from Arduino to control the relay.

Contacts : This part performs the electrical switching, typically categorized as NO (Normally Open), NC (Normally Closed), and COM (Common).

Relay Operating Principle

It operates based on electromagnetic principles. Inside, there is a coil, and when current flows through it via the control pin, the coil generates a magnetic field that activates the internal switch.

Low Level Trigger : When a low voltage (typically 0V or GND) is applied to the control pin, the relay is activated.

High Level Trigger : When a high voltage (typically 5V) is applied to the control pin, the relay is activated.

Example Hardware Used

• Arduino
• Relay Module
• Jumper Cable
• Resistor
• LED

Usage Example

1. 1 Channel Relay

This is an example of changing the state of a single-channel relay three times. The changes can be confirmed through an LED.

1-1. Connections

Arduino Nano	Relay	LED Red	LED Green
5V	VCC
3.3V	2
GND	GND	-	-
D4	In1
	1	+
	3		+

1-2. Code

const int relay = 4;

void setup() {
  pinMode(relay, OUTPUT);
  digitalWrite(relay, HIGH);
}

void loop() {
  for (int i = 0; i < 3; i++) {
    digitalWrite(relay, LOW);
    delay(500);
    digitalWrite(relay, HIGH);
    delay(500);
  }
  delay(9999);
}

2. 2-Channel Relay

This example controls each LED connected to the two channels so that they turn on in sequence and then turn off again.

2-1. Connections

Arduino Uno	2ch Relay Module	Resistor1	Resistor2	LED1	LED2
GND	Gnd			K	K
5V	Vcc, 2, 4
D6	IN1
D7	IN2
	1	Connect
	3		Connect
		Connect		A
			Connect		A

2-2. Code

#define IN1 6
#define IN2 7

void setup() {
  pinMode(IN1, OUTPUT);
  pinMode(IN2, OUTPUT);
  digitalWrite(IN1, HIGH);
  digitalWrite(IN2, HIGH);
  delay(300);
  digitalWrite(IN1, LOW);
  delay(300);
  digitalWrite(IN2, LOW);
  delay(300);
  digitalWrite(IN1, HIGH);
  delay(300);
  digitalWrite(IN2, HIGH);
  delay(300);
}

void loop() {
}

3. 4-Channel Relay

This is an example of controlling each LED connected to the four channels to turn on in sequence and then turn off.

3-1. Connections

Arduino	4ch relay module	LED1	LED2	LED3	LED4	Resistor1	Resistor2	Resistor3	Resistor4	5V
5V	VCC
GND	GND	K	K	K	K					-
D8	IN1
D9	IN2
D10	IN3
D11	IN4
	1					Connect
	3						Connect
	5							Connect
	7								Connect
	2,4,6,8									+
		A				Connect
			A				Connect
				A				Connect
					A				Connect

3-2. Code

#define IN1 8
#define IN2 9
#define IN3 10
#define IN4 11

void setup() {
  for (int i = 0; i < 4; i++) {
    pinMode(IN1 + i, OUTPUT);
    digitalWrite(IN1 + i, HIGH);
  }
  delay(100);
  for (int i = 0; i < 4; i++) {
    digitalWrite(IN1 + i, LOW);
    delay(100);
  }
  delay(1000);
  for (int i = 0; i < 4; i++) {
    digitalWrite(IN1 + i, HIGH);
    delay(100);
  }
  delay(2000);
}

void loop() {
}

4. 8-Channel Relay

This is an example of controlling each LED connected to the eight channels to turn on in sequence and then turn off.

4-1. Connections

4-2. Code

const int IN8 = 4;
const int IN7 = 5;
const int IN6 = 6;
const int IN5 = 7;
const int IN4 = 8;
const int IN3 = 9;
const int IN2 = 10;
const int IN1 = 11;

void setup() {
  Serial.begin(9600);
  for (int i = 0; i < 8; i++) {
    pinMode(IN8 + i, OUTPUT);
    digitalWrite(IN8 + i, HIGH);
  }
  delay(100);
  for (int i = 0; i < 8; i++) {
    digitalWrite(IN1 - i, LOW);
    delay(100);
  }
  delay(1000);
  for (int i = 0; i < 8; i++) {
    digitalWrite(IN1 - i, HIGH);
    delay(100);
  }
}

void loop() {
}

Precautions

• The power supply to the relay module should be stable.
• Safety should be prioritized when handling high-voltage devices.
• Care should be taken not to exceed the maximum current and voltage ratings of the relay module.

Applications

1. Home Automation

• Lighting Control: Relays can be used to remotely turn on and off home lighting.
• Appliance Control: Various appliances like air conditioners, heaters, and coffee machines can be controlled.

2. Security Systems

• Door Lock Control: Relays can be used to control electronic door locks.
• Alarm Systems: A security system can be built by integrating sensors with relays.

3. Automated Control Systems

• Temperature Control: Temperature sensors and relays can be used to control fans or heaters.
• Water Pump Control: Water pumps can be automatically controlled in conjunction with level sensors.

4. Remote Control

• IoT (Internet of Things) Projects: Relays can be controlled remotely via the internet to manage various devices.

5. Traffic Signal Control

• Traffic Lights: Relays can be used to control traffic signal systems.

Purchase Links

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