How to Use 1 Channel Relay 5V: Examples, Pinouts, and Specs

The 1 Channel Relay 5V is an electromechanical switch module that allows a low voltage control signal (e.g., from a microcontroller) to control a higher voltage circuit. This module is widely used in automation, home appliances, and industrial control systems to safely isolate and switch high-power devices such as lights, motors, and heaters.

• Home automation (e.g., controlling lights or fans)
• Industrial control systems
• IoT projects
• Motor control
• Smart home devices

The following table outlines the key technical details of the 1 Channel Relay 5V module:

The 1 Channel Relay 5V module has the following pins:

1. Power the Module: Connect the VCC pin to a 5V DC power source and the GND pin to ground.
2. Control Signal: Connect the IN pin to a digital output pin of a microcontroller (e.g., Arduino UNO). The relay will activate when the control signal is HIGH.
3. Load Connection:
   • Connect the device you want to control (e.g., a light bulb) to the NO (Normally Open) terminal.
   • Connect the other end of the device to the power source.
   • The COM terminal should be connected to the other side of the power source.
4. Isolation: Ensure proper isolation between the low voltage control circuit and the high voltage load circuit to prevent damage or hazards.

Below is an example of how to connect the 1 Channel Relay 5V to an Arduino UNO to control a light bulb:

• Relay Module:
  • VCC → 5V pin on Arduino
  • GND → GND pin on Arduino
  • IN → Digital pin 7 on Arduino
• Load:
  • Connect the light bulb to the NO terminal and the power source.
  • Connect the COM terminal to the other side of the power source.

// Example code to control a 1 Channel Relay 5V with Arduino UNO

#define RELAY_PIN 7  // Define the digital pin connected to the relay module

void setup() {
  pinMode(RELAY_PIN, OUTPUT);  // Set the relay pin as an output
  digitalWrite(RELAY_PIN, LOW);  // Ensure the relay is off at startup
}

void loop() {
  digitalWrite(RELAY_PIN, HIGH);  // Turn the relay ON (activates the load)
  delay(5000);  // Keep the relay ON for 5 seconds
  digitalWrite(RELAY_PIN, LOW);  // Turn the relay OFF
  delay(5000);  // Keep the relay OFF for 5 seconds
}

• Power Supply: Ensure the relay module is powered with a stable 5V DC supply.
• Load Ratings: Do not exceed the maximum voltage (250V AC / 30V DC) or current (10A) ratings of the relay.
• Isolation: Use optocoupler isolation to protect the microcontroller from high voltage spikes.
• Flyback Diode: If controlling an inductive load (e.g., a motor), use a flyback diode across the load to prevent voltage spikes.

1. Relay Not Activating:

   • Check if the VCC and GND connections are secure.
   • Ensure the control signal (IN pin) is receiving the correct voltage (3.3V to 5V).
   • Verify that the Arduino pin is set as an output and is providing the correct signal.

2. Load Not Switching:

   • Confirm that the load is properly connected to the NO and COM terminals.
   • Check the load's power source and ensure it is functioning correctly.
   • Verify that the load does not exceed the relay's voltage or current ratings.

3. Relay Stuck in ON or OFF State:

   • Inspect the relay module for physical damage or debris.
   • Ensure the control signal is toggling correctly between HIGH and LOW states.

4. Indicator LED Not Lighting Up:

   • Check the VCC and GND connections.
   • Ensure the control signal is HIGH when the relay is supposed to activate.

Q1: Can I use the 1 Channel Relay 5V with a 3.3V microcontroller like ESP8266?
A1: Yes, the relay module can be triggered with a 3.3V control signal. However, ensure the VCC pin is still powered with 5V.

Q2: Is the relay safe for switching high-power devices?
A2: Yes, the relay is designed for high-power devices up to 250V AC or 30V DC at 10A. Always ensure proper isolation and follow safety guidelines.

Q3: Can I control multiple relays with one Arduino?
A3: Yes, you can control multiple relays by connecting each relay's IN pin to a separate digital output pin on the Arduino.

Q4: Why is the relay clicking but not switching the load?
A4: This could be due to incorrect wiring of the load or a faulty relay. Double-check the connections and ensure the load is within the relay's specifications.