How to Use MX-RM-5V: Examples, Pinouts, and Specs

The MX-RM-5V is a 5V relay module designed to enable the control of high-voltage devices using low-voltage signals. This module is commonly used in automation, home appliances, and control systems where electrical isolation and safety are critical. It features an opto-isolator to protect the low-voltage control circuit from high-voltage spikes, making it a reliable choice for switching AC or DC loads.

• Home automation systems (e.g., controlling lights, fans, or appliances)
• Industrial control systems
• Robotics and IoT projects
• Motor control and power management
• Arduino and microcontroller-based projects

The MX-RM-5V relay module is designed for ease of use and compatibility with a wide range of microcontrollers and circuits. Below are its key technical details:

The MX-RM-5V module typically has six pins or terminals. Below is the pinout description:

1. Power the Module: Connect the VCC pin to a 5V DC power supply and the GND pin to the ground.
2. Control Signal: Connect the IN pin to a microcontroller (e.g., Arduino) or a low-voltage control circuit. A HIGH signal (3.3V to 5V) will activate the relay.
3. Load Connection:
   • Connect the power source or load to the COM terminal.
   • Use the NO terminal if you want the load to be OFF by default and turn ON when the relay is activated.
   • Use the NC terminal if you want the load to be ON by default and turn OFF when the relay is activated.
4. Isolation: Ensure proper electrical isolation between the low-voltage control circuit and the high-voltage load.

Below is an example of how to connect and control the MX-RM-5V relay module using an Arduino UNO:

• Connect the VCC pin of the relay module to the 5V pin on the Arduino.
• Connect the GND pin of the relay module to the GND pin on the Arduino.
• Connect the IN pin of the relay module to digital pin 7 on the Arduino.
• Connect the load (e.g., a light bulb) to the COM and NO terminals of the relay.

// Define the relay control pin
const int relayPin = 7;

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

void loop() {
  // Turn the relay ON
  digitalWrite(relayPin, HIGH);
  delay(5000); // Keep the relay ON for 5 seconds
  
  // Turn the relay OFF
  digitalWrite(relayPin, LOW);
  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 load voltage (250V AC / 30V DC) or current (10A).
• Isolation: Always use the opto-isolator feature to protect your control circuit from high-voltage spikes.
• Safety: When working with high-voltage loads, ensure proper insulation and follow electrical safety guidelines.

1. Relay Not Activating:

   • Check if the VCC and GND connections are secure.
   • Ensure the control signal (IN pin) is within the required voltage range (3.3V to 5V).
   • Verify that the power supply provides sufficient current for the relay module.

2. Load Not Switching:

   • Confirm that the load is properly connected to the COM and NO/NC terminals.
   • Check the load's voltage and current ratings to ensure they are within the relay's specifications.
   • Inspect the relay module for any physical damage or loose connections.

3. Interference with Microcontroller:

   • Use a separate power supply for the relay module to avoid noise interference.
   • Add a flyback diode across the relay coil to suppress voltage spikes.

Q: Can I use the MX-RM-5V with a 3.3V microcontroller like the ESP8266?
A: Yes, the relay module can be triggered with a 3.3V control signal. However, ensure the module's VCC is powered with 5V.

Q: Is the relay module suitable for switching inductive loads like motors?
A: Yes, but it is recommended to use a snubber circuit or flyback diode to protect the relay from voltage spikes caused by inductive loads.

Q: Can I control multiple relays with one microcontroller?
A: Yes, as long as the microcontroller has enough GPIO pins and the total current draw does not exceed its limits.

Q: How do I know if the relay is activated?
A: The relay module typically includes an onboard LED that lights up when the relay is activated.