How to Use Amphenol ACJS-MHDR 6.35mm Switched Stereo Jack: Examples, Pinouts, and Specs

The Amphenol ACJS-MHDR is a high-quality 6.35mm (1/4 inch) switched stereo jack designed for audio applications. This component is widely used in audio equipment to connect stereo audio signals, such as headphones, amplifiers, and musical instruments. Its built-in switch functionality allows it to control other circuit elements when a plug is inserted, making it a versatile choice for signal routing and control in audio systems.

• Audio equipment such as mixers, amplifiers, and audio interfaces
• Musical instruments like electric guitars and keyboards
• Headphone jacks in professional audio systems
• Signal routing in audio processing circuits

The ACJS-MHDR has five pins, as detailed in the table below:

1. Mounting the Jack: Secure the ACJS-MHDR to a panel or enclosure using the provided mounting hardware. Ensure the jack is properly aligned for easy plug insertion.
2. Wiring the Audio Signals:
   • Connect the Left (L) pin to the left audio signal source.
   • Connect the Right (R) pin to the right audio signal source.
   • Connect the Ground (G) pin to the common ground of the circuit.
3. Using the Switch Contacts:
   • The Switch 1 and Switch 2 pins can be used to control other circuit elements. For example, they can disconnect a speaker when a headphone plug is inserted.
   • When no plug is inserted, the switch contacts are closed, allowing current to flow. When a plug is inserted, the contacts open, interrupting the circuit.

• Signal Integrity: Use shielded cables for audio signals to minimize noise and interference.
• Switch Ratings: Ensure the switch contacts are not subjected to currents or voltages beyond their rated capacity.
• Mechanical Stress: Avoid excessive force when inserting or removing plugs to prevent damage to the jack.
• Soldering: Use a soldering iron with a temperature-controlled tip to avoid overheating the pins during assembly.

The ACJS-MHDR can be used with an Arduino UNO to detect when a plug is inserted. Below is an example circuit and code:

• Connect Switch 1 to an Arduino digital input pin (e.g., pin 2).
• Connect Switch 2 to the Arduino ground (GND).
• Use a pull-up resistor (internal or external) to ensure a stable signal.

// Define the pin connected to Switch 1
const int switchPin = 2;

// Variable to store the switch state
int switchState = 0;

void setup() {
  // Configure the switch pin as an input with an internal pull-up resistor
  pinMode(switchPin, INPUT_PULLUP);
  
  // Initialize serial communication for debugging
  Serial.begin(9600);
}

void loop() {
  // Read the state of the switch (LOW when plug is inserted)
  switchState = digitalRead(switchPin);
  
  // Print the switch state to the serial monitor
  if (switchState == LOW) {
    Serial.println("Plug inserted");
  } else {
    Serial.println("No plug detected");
  }
  
  // Add a small delay to avoid spamming the serial monitor
  delay(500);
}

1. No Audio Signal:
   • Check the connections to the Left (L), Right (R), and Ground (G) pins.
   • Ensure the audio source and destination are powered and functioning correctly.
2. Switch Not Working:
   • Verify the wiring of Switch 1 and Switch 2.
   • Check for continuity using a multimeter to ensure the switch contacts are functioning.
3. Noise or Interference:
   • Use shielded cables and ensure proper grounding.
   • Avoid running audio cables near high-power or high-frequency circuits.

• Testing the Jack: Use a multimeter to test continuity between the pins and verify the switch operation.
• Plug Compatibility: Ensure the plug used is a standard 6.35mm stereo plug for proper contact alignment.
• Durability: Periodically inspect the jack for wear and tear, especially in high-use environments.

By following this documentation, users can effectively integrate the Amphenol ACJS-MHDR 6.35mm Switched Stereo Jack into their audio projects and troubleshoot common issues with ease.