How to Use QTRX 13A: Examples, Pinouts, and Specs

The QTRX 13A, manufactured by Pololu (Part ID: HD 13A), is a high-performance relay designed for switching applications. It is capable of handling up to 13 amps of current, making it ideal for controlling high-power devices in electronic circuits. Its compact design ensures easy integration into various projects, including home automation, industrial control systems, and robotics.

• Home automation systems (e.g., controlling lights, fans, or appliances)
• Industrial equipment control
• Robotics and motor control
• Power management in electronic circuits
• Automotive electronics

The QTRX 13A relay is designed to provide reliable performance in demanding applications. Below are its key technical details:

The QTRX 13A relay has five pins, as described in the table below:

1. Power the Relay Coil: Connect the Coil+ pin to a 5 V DC power source and the Coil- pin to ground. This energizes the relay coil and switches the contacts.
2. Connect the Load:
   • For devices that should turn on when the relay is activated, connect the load between the COM and NO pins.
   • For devices that should turn off when the relay is activated, connect the load between the COM and NC pins.
3. Control the Relay: Use a microcontroller (e.g., Arduino UNO) or a transistor circuit to control the relay coil. Ensure the control circuit can handle the relay's coil current.

• Flyback Diode: Always use a flyback diode across the relay coil to protect the control circuit from voltage spikes when the relay is deactivated.
• Current Rating: Ensure the load current does not exceed the relay's maximum rating of 13 A.
• Isolation: Use optocouplers or transistors to isolate the relay from sensitive control circuits if needed.

Below is an example of how to control the QTRX 13A relay using an Arduino UNO:

// Example code to control the QTRX 13A relay with an Arduino UNO

const int relayPin = 7; // Pin connected to the relay's control circuit

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

void loop() {
  digitalWrite(relayPin, HIGH); // Activate the relay
  delay(5000); // Keep the relay on for 5 seconds
  digitalWrite(relayPin, LOW); // Deactivate the relay
  delay(5000); // Keep the relay off for 5 seconds
}

Note: Use a transistor or relay driver circuit between the Arduino and the relay to handle the coil current safely.

1. Relay Not Activating

   • Cause: Insufficient voltage or current to the relay coil.
   • Solution: Verify the power supply to the Coil+ and Coil- pins. Ensure the control circuit can provide enough current.

2. Load Not Switching

   • Cause: Incorrect wiring of the load to the relay contacts.
   • Solution: Double-check the connections to the COM, NO, and NC pins.

3. Voltage Spikes Damaging the Circuit

   • Cause: Lack of a flyback diode across the relay coil.
   • Solution: Add a flyback diode (e.g., 1N4007) across the Coil+ and Coil- pins.

Q: Can the QTRX 13A handle AC loads?
A: Yes, the relay can handle AC loads up to 250 V, provided the current does not exceed 13 A.

Q: What is the minimum voltage required to activate the relay?
A: The relay requires a 5 V DC supply to activate the coil.

Q: Can I use the QTRX 13A with a 3.3 V microcontroller?
A: Yes, but you will need a transistor or relay driver circuit to step up the control voltage to 5 V for the relay coil.

Q: Is the relay suitable for switching inductive loads?
A: Yes, but ensure proper snubber circuits or flyback diodes are used to suppress voltage spikes.