2 Channel Relay Module

A 2-Channel Relay Module is an electronic module that allows you to control two separate devices (such as lights, motors, or other high-voltage appliances) using a low-voltage control signal, like from a microcontroller (e.g., Arduino or Raspberry Pi). The module uses relays to isolate and switch high-power devices safely using low-power signals.

Overview of 2-Channel Relay Module:

• Relay: A relay is an electrically operated switch. When the control signal is received, the relay switches the circuit from an "off" state to an "on" state (or vice versa), allowing current to flow through a connected high-power device.
• 2-Channel: This refers to the fact that the module contains two relays, meaning it can control two separate devices at once.
• Low Power Control, High Power Switching: The module allows you to control devices that use high current or high voltage (like 220V AC appliances) from a low-voltage control system (like an Arduino, which operates at 5V or 3.3V).

Key Features:

1. Channels: The 2-channel relay module allows control of two different circuits. Each relay can control a device independently.
2. Relay Type: The module typically uses SPDT (Single Pole Double Throw) or DPDT (Double Pole Double Throw) relays, which can either be normally open (NO) or normally closed (NC).
3. Control Pins: The module will have pins for controlling the relays, usually labeled as IN1, IN2, where you send a control signal (HIGH or LOW).
4. Power Supply: The module usually operates on a 5V DC supply, which powers the relay’s coil and internal logic.
5. Optocoupler Isolation: Most 2-channel relay modules have optocouplers that provide electrical isolation between the low-voltage control side (like Arduino) and the high-voltage side (the device being controlled).

Pinout of a 2-Channel Relay Module:

1. VCC (Power): This pin connects to the 5V supply of the microcontroller or a separate power supply to power the relay module.
2. GND (Ground): Connect to the ground (GND) of your control circuit (e.g., Arduino or Raspberry Pi).
3. IN1 & IN2 (Control Inputs): These are the pins that you connect to your microcontroller to control the relays. A HIGH signal will turn the relay ON, and a LOW signal will turn it OFF.
4. NO (Normally Open): The NO terminal of the relay is where you connect the high-power device. When the relay is activated, the circuit closes between NO and COM.
5. NC (Normally Closed): The NC terminal is also connected to the high-power device but will be active when the relay is NOT activated (it’s an alternative to NO).
6. COM (Common): The common terminal is the shared connection between the relay and the device you are controlling.

How It Works:

• When the control input pin (IN1 or IN2) receives a HIGH signal from the microcontroller, it activates the relay, causing the NO and COM pins to connect. This completes the circuit and allows power to flow to the high-power device.
• When the control pin is LOW, the relay is deactivated, and the COM pin is disconnected from the NO pin (or connected to NC, depending on your circuit configuration), thus turning off the device.

Applications:

1. Home Automation: Control home appliances such as lights, fans, or security systems using microcontrollers like Arduino or Raspberry Pi.
2. Automated Systems: Turn on/off equipment in industrial or research setups.
3. IoT Projects: Enable remote control of electrical devices using wireless modules (e.g., Wi-Fi or Bluetooth) integrated with the relay.
4. Automation of Electrical Devices: For example, turning on/off a water pump, controlling a door lock, or switching on/off high-power motors.

Example: Controlling a Light with a 2-Channel Relay Module and Arduino

Here's a basic example where you use the relay module to control a light:

Wiring:

1. Relay Module:

• VCC → 5V on Arduino
• GND → GND on Arduino
• IN1 → Pin 7 on Arduino (Control Pin for Relay 1)
• IN2 → Pin 8 on Arduino (Control Pin for Relay 2)
• COM1 → Common Pin for the first device (e.g., a light)
• NO1 → Normally Open Pin for the first device
• COM2 → Common Pin for the second device (if needed)
• NO2 → Normally Open Pin for the second device (if needed)

1. Arduino Code Example:

int relayPin1 = 7;  // Pin connected to IN1 of relay
int relayPin2 = 8;  // Pin connected to IN2 of relay

void setup() {
  pinMode(relayPin1, OUTPUT);  // Set relayPin1 as output
  pinMode(relayPin2, OUTPUT);  // Set relayPin2 as output
  Serial.begin(9600);  // Start serial communication
}

void loop() {
  // Turn on Relay 1 (light ON)
  digitalWrite(relayPin1, HIGH);  
  Serial.println("Relay 1 ON");
  delay(2000);  // Wait for 2 seconds

  // Turn off Relay 1 (light OFF)
  digitalWrite(relayPin1, LOW);  
  Serial.println("Relay 1 OFF");
  delay(2000);  // Wait for 2 seconds

  // You can control Relay 2 similarly (if you have a second device connected)
}

1. Explanation:

• In the setup(), the pins connected to the relay module are set as OUTPUT.
• In the loop(), Relay 1 is turned on for 2 seconds, and then turned off for 2 seconds.

Advantages of Using a 2-Channel Relay Module:

1. Multiple Device Control: You can control two separate devices with a single module.
2. Isolation: Provides electrical isolation between your low-voltage control system and the high-voltage appliances, reducing the risk of damaging your microcontroller.
3. Easy Integration: Simple to use with common platforms like Arduino, Raspberry Pi, or other microcontroller-based projects.
4. Affordable and Compact: These modules are inexpensive and compact, making them ideal for DIY projects and home automation systems.

Origin:- China

Brand:- Generic