How to Use HK19F-DC Relay (AUX/RCA Board): Examples, Pinouts, and Specs

The HK19F-DC Relay is an electromagnetic switching device commonly used in AUX/RCA audio boards. It allows low-voltage control circuits to manage higher voltage or current signals, making it ideal for audio signal routing or power control applications. This relay is compact, reliable, and designed for use in low-power electronic systems.

• Switching audio signals in AUX/RCA boards
• Controlling power to audio amplifiers or other devices
• General-purpose low-power switching in electronic circuits
• Signal isolation between control and load circuits

The HK19F-DC Relay typically has 5 pins. The pinout is as follows:

1. Power the Coil: Connect the relay coil pins (1 and 2) to a DC voltage source matching the relay's rated coil voltage (e.g., 5V DC). Use a transistor or MOSFET to control the coil if driven by a microcontroller.
2. Connect the Load:
   • Connect the load to the Common (COM) pin (Pin 3).
   • Use the Normally Open (NO) pin (Pin 4) if the load should be powered only when the relay is activated.
   • Use the Normally Closed (NC) pin (Pin 5) if the load should be powered when the relay is inactive.
3. Add a Flyback Diode: Place a diode (e.g., 1N4007) across the coil terminals to protect the circuit from voltage spikes when the relay is deactivated.
4. Control the Relay: Use a microcontroller, such as an Arduino UNO, to control the relay by switching the coil on and off.

• Ensure the coil voltage matches the relay's rated voltage to avoid damage.
• Do not exceed the contact rating (1A at 30V DC or 0.5A at 125V AC) to prevent overheating or failure.
• Use proper insulation and spacing to avoid short circuits, especially in high-voltage applications.
• For audio applications, ensure the relay's switching noise does not interfere with the signal quality.

Below is an example of how to control the HK19F-DC Relay using an Arduino UNO:

// Example: Controlling the HK19F-DC Relay with Arduino UNO
// Pin 7 is used to control the relay via a transistor or MOSFET

const int relayPin = 7; // Define the pin connected to the relay 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(1000); // Keep the relay on for 1 second
  digitalWrite(relayPin, LOW); // Deactivate the relay
  delay(1000); // Keep the relay off for 1 second
}

Note: Use a transistor or MOSFET to drive the relay coil, as the Arduino's GPIO pins cannot supply sufficient current directly.

1. Relay Not Activating

   • Cause: Insufficient coil voltage or current.
   • Solution: Verify the power supply voltage and ensure it matches the relay's rated coil voltage. Check the transistor or MOSFET driver circuit.

2. Relay Stuck in One State

   • Cause: Damaged relay contacts or coil.
   • Solution: Replace the relay if it is physically damaged or not switching properly.

3. Noise in Audio Signals

   • Cause: Relay switching noise or improper grounding.
   • Solution: Use a relay with low switching noise and ensure proper grounding in the circuit.

4. Voltage Spikes Damaging Components

   • Cause: Lack of a flyback diode across the relay coil.
   • Solution: Add a flyback diode (e.g., 1N4007) across the coil terminals to suppress voltage spikes.

• Q: Can the HK19F-DC Relay handle AC loads?
  A: Yes, it can handle AC loads up to 0.5A at 125V AC, but ensure the load does not exceed the contact rating.

• Q: Is the relay suitable for high-frequency switching?
  A: No, the HK19F-DC Relay is not designed for high-frequency switching. Use a solid-state relay for such applications.

• Q: Can I use the relay directly with an Arduino GPIO pin?
  A: No, the Arduino GPIO pin cannot supply enough current to drive the relay coil. Use a transistor or MOSFET as a driver.

By following this documentation, you can effectively integrate the HK19F-DC Relay into your electronic projects for reliable switching applications.