How to Use PT2399: Examples, Pinouts, and Specs

The PT2399, manufactured by Princeton Technology Corp, is a digital delay chip designed for audio applications. It is widely used in devices such as guitar pedals, karaoke systems, and audio processors to create echo and delay effects. The chip combines digital signal processing with an analog interface, making it a versatile and cost-effective solution for audio delay effects. Its adjustable delay time and feedback make it a popular choice for both hobbyists and professionals in the audio industry.

• Guitar effects pedals (e.g., delay and echo effects)
• Karaoke machines
• Audio mixing consoles
• DIY audio projects
• Sound effects processors

The PT2399 is a monolithic IC that integrates digital delay processing with analog input/output stages. Below are its key technical details:

The PT2399 is available in a 16-pin DIP or SOP package. Below is the pinout and description:

The PT2399 is straightforward to use in audio delay circuits. Below are the steps and considerations for integrating it into your design:

1. Power Supply: Provide a stable 5V DC power supply to the VDD pin (Pin 8). Connect AGND (Pins 1 and 16) and DGND (Pin 5) to the ground.
2. Audio Input: Feed the audio signal into the LIN (Pin 14) and/or RIN (Pin 15) pins. Use coupling capacitors to block DC components.
3. Delay Time Adjustment: Connect an external resistor and capacitor to the OSC1 (Pin 6) and OSC2 (Pin 7) pins to set the delay time. The delay time can be calculated using the formula provided in the PT2399 datasheet.
4. Audio Output: The delayed audio signal is available at the LOUT (Pin 13) and ROUT (Pin 2) pins. Use coupling capacitors to connect these outputs to the next stage of your circuit.
5. Low-Pass Filter: Use the LPF_IN (Pin 10) and LPF_OUT (Pin 9) pins to implement a low-pass filter for smoothing the delayed signal.

The PT2399 can be controlled using an Arduino to adjust the delay time dynamically. Below is an example code snippet:

// PT2399 Delay Time Control with Arduino
// This example uses a potentiometer connected to an analog pin to adjust delay time.

const int potPin = A0;  // Potentiometer connected to analog pin A0
const int vcoPin = 9;   // VCO pin connected to digital pin 9 (PWM output)

void setup() {
  pinMode(vcoPin, OUTPUT);  // Set VCO pin as output
}

void loop() {
  int potValue = analogRead(potPin);  // Read potentiometer value (0-1023)
  
  // Map potentiometer value to PWM duty cycle (0-255)
  int pwmValue = map(potValue, 0, 1023, 0, 255);
  
  // Output PWM signal to VCO pin
  analogWrite(vcoPin, pwmValue);
  
  delay(10);  // Small delay for stability
}

• Use decoupling capacitors (e.g., 0.1µF) near the power supply pins to reduce noise.
• Keep the external resistor and capacitor for the oscillator as close to the chip as possible to minimize interference.
• Use shielded cables for audio input and output to reduce noise and hum.
• Avoid exceeding the maximum supply voltage (5.5V) to prevent damage to the chip.

1. No Output Signal:

   • Check the power supply voltage and ensure it is within the specified range (4.5V to 5.5V).
   • Verify that the audio input signal is properly connected and within the acceptable range.
   • Ensure that the external oscillator components (resistor and capacitor) are correctly connected.

2. Distorted Output:

   • Check the low-pass filter design and ensure it is properly tuned.
   • Verify that the input signal level is not too high, as this can cause clipping.

3. Excessive Noise:

   • Use proper grounding techniques to minimize noise.
   • Ensure that the power supply is clean and free from ripple.

Q: Can the PT2399 be used for stereo audio processing?
A: Yes, the PT2399 has separate left and right input/output pins, making it suitable for stereo applications.

Q: How do I calculate the delay time?
A: The delay time is determined by the external resistor and capacitor connected to the OSC1 and OSC2 pins. Refer to the PT2399 datasheet for the exact formula.

Q: What is the maximum delay time achievable with the PT2399?
A: The maximum delay time is approximately 340ms, depending on the external oscillator components.

Q: Can I use the PT2399 with a 3.3V power supply?
A: No, the PT2399 requires a minimum supply voltage of 4.5V to operate correctly.

By following this documentation, you can effectively integrate the PT2399 into your audio projects and achieve high-quality delay and echo effects.