DIY Audio Amplifier Board

by Arnov Sharma in Circuits > Audio

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DIY Audio Amplifier Board

Greetings everyone, and welcome back.

Here's a small audio-based project I prepared for an upcoming Game Boy project.

The PAM8403 Audio Amplifier IC Setup, in addition to a few additional components, drives a 3 ohm speaker on this audio board.

Since the PAM8403 is a 5V device and will short circuit if given more than 5V, we integrated the AMS1117 linear voltage regulator setup. To charge the battery, we have added a con2 port that is connected through a diode, and we can also connect a DC barrel jack to this setup. The battery supply used in this audio board is a 12V Li-ion battery pack.

This audio board essentially serves as a battery power distribution board, charging the battery and supplying other devices with 12V and 5V power from the battery in addition to a separate audio amplifier board for audio output.

This project is about the whole construction of this project, so let's get started with the build.

Supplies

Below are the materials used in this project:

Custom PCB (Provided by Seeed Studio Fusion)
PAM8403 Audio Amplifier IC
AMS1117 Voltage Regulator 5V
1uF 0603 Capacitors
0.47uF, 0603 Capacitors
10uF 1206 Capacitor
1uF 1206 Capacitor
220pF 0603 Capacitors
SR206 Diode
M7 Diode SMA Package
CON2 JST Connector
Rocker Switch
3 Ohms Speaker
3.5mm Audio Jack Cable
XIAO SAMD21

PCB Design

We started the project by first looking into the PAM8430 datasheet and understanding the workings of the amplifier IC.

Using the provided minimal connection diagram for PAM8403, we created the design. Following the datasheet's instructions, we included a coupling of capacitors to reduce noise and smooth out the output side (speaker side) of the signal.

Since the PAM8403 is a 5V device and we intend to utilize a 12V battery source, we selected the widely used AMS1117 voltage regulator IC, a low dropout (LDO) voltage regulator that is frequently used to control voltage levels in a variety of electrical projects and applications.

Check out its datasheet here. https://www.advanced-monolithic.com/pdf/ds1117.pdf

Additionally, we added a CON2 Port, which we will use to connect a rocker switch for switching the audio board ON and off, between the battery positives and the VDD Pin.

In order to charge the battery pack, we added an additional CON2 port, which is connected to the anode of a diode and its cathode to the positive port of the battery.

Additionally, there is an LED and resistor connected to the CON2 port that serve as a charging indication. The indicator LED will illuminate when 12+V is applied to the CON2 port.

Following the completion of the schematic, we used the PCB outline—which was modeled for the next project—to produce the PCB design and complete the board.

Seeed Fusion Service

After finalizing the PCB and generating its Gerber data, it was sent to SEEED Studio for samples.

The PCB was ordered in a white solder mask with black silkscreen.

PCBs were received in a week, and their quality was super good considering the rate, which was also pretty low.

Seeed Fusion PCB Service offers one-stop prototyping for PCB manufacture and PCB assembly, and as a result, they produce superior-quality PCBs and fast turnkey PCBAs within 7 working days.

Seeed Studio Fusion PCB Assembly Service takes care of the entire fabrication process, from Seeed Studio Fusion Agile manufacturing and hardware customization to parts sourcing, assembly, and testing services, so you can be sure that they are getting a quality product.

After gauging market interest and verifying a working prototype, Seeed Propagate Service can help you bring the product to market with professional guidance and a strong network of connections.

Next is the PCB assembly process.

PCB Assembly Process

Using a solder paste dispensing syringe, the solder paste is first added to the PCB during PCB assembly.
Next, we pick and place all the SMD components in their places using an ESD tweezer.
Following the pick and place procedure, we placed the PCB on the SMT Reflow hotplate, which heats the board from below to the melting point of the solder paste. The solder melts at that temperature, soldering every component to its pad.
The THT process followed next. To begin, we placed the THT diode and soldered its pads to the PCB's bottom side. We placed CON2 port on the PCB Next and repeated the same process.

PCB assembly was completed.

Wiring

For testing this audio board, we needed to first connect the battery to it along with the rocker switch and the speaker.

We did the wiring by following the wiring schematic attached.

The audio module was tested using the XIAO SamD21 M0 Dev Board. We uploaded a test sketch that output the Super Mario theme music on loop via the D3 pin of the XIAO. We linked the D3 pin of XIAO to the R-IN port of the audio module.

CODE

Here's the Super Mario theme song code that was used in this project.

#define NOTE_B0  31
#define NOTE_C1  33
#define NOTE_CS1 35
#define NOTE_D1  37
#define NOTE_DS1 39
#define NOTE_E1  41
#define NOTE_F1  44
#define NOTE_FS1 46
#define NOTE_G1  49
#define NOTE_GS1 52
#define NOTE_A1  55
#define NOTE_AS1 58
#define NOTE_B1  62
#define NOTE_C2  65
#define NOTE_CS2 69
#define NOTE_D2  73
#define NOTE_DS2 78
#define NOTE_E2  82
#define NOTE_F2  87
#define NOTE_FS2 93
#define NOTE_G2  98
#define NOTE_GS2 104
#define NOTE_A2  110
#define NOTE_AS2 117
#define NOTE_B2  123
#define NOTE_C3  131
#define NOTE_CS3 139
#define NOTE_D3  147
#define NOTE_DS3 156
#define NOTE_E3  165
#define NOTE_F3  175
#define NOTE_FS3 185
#define NOTE_G3  196
#define NOTE_GS3 208
#define NOTE_A3  220
#define NOTE_AS3 233
#define NOTE_B3  247
#define NOTE_C4  262
#define NOTE_CS4 277
#define NOTE_D4  294
#define NOTE_DS4 311
#define NOTE_E4  330
#define NOTE_F4  349
#define NOTE_FS4 370
#define NOTE_G4  392
#define NOTE_GS4 415
#define NOTE_A4  440
#define NOTE_AS4 466
#define NOTE_B4  494
#define NOTE_C5  523
#define NOTE_CS5 554
#define NOTE_D5  587
#define NOTE_DS5 622
#define NOTE_E5  659
#define NOTE_F5  698
#define NOTE_FS5 740
#define NOTE_G5  784
#define NOTE_GS5 831
#define NOTE_A5  880
#define NOTE_AS5 932
#define NOTE_B5  988
#define NOTE_C6  1047
#define NOTE_CS6 1109
#define NOTE_D6  1175
#define NOTE_DS6 1245
#define NOTE_E6  1319
#define NOTE_F6  1397
#define NOTE_FS6 1480
#define NOTE_G6  1568
#define NOTE_GS6 1661
#define NOTE_A6  1760
#define NOTE_AS6 1865
#define NOTE_B6  1976
#define NOTE_C7  2093
#define NOTE_CS7 2217
#define NOTE_D7  2349
#define NOTE_DS7 2489
#define NOTE_E7  2637
#define NOTE_F7  2794
#define NOTE_FS7 2960
#define NOTE_G7  3136
#define NOTE_GS7 3322
#define NOTE_A7  3520
#define NOTE_AS7 3729
#define NOTE_B7  3951
#define NOTE_C8  4186
#define NOTE_CS8 4435
#define NOTE_D8  4699
#define NOTE_DS8 4978

#define melodyPin 3
//Mario main theme melody
int melody[] = {
  NOTE_E7, NOTE_E7, 0, NOTE_E7,
  0, NOTE_C7, NOTE_E7, 0,
  NOTE_G7, 0, 0,  0,
  NOTE_G6, 0, 0, 0,

  NOTE_C7, 0, 0, NOTE_G6,
  0, 0, NOTE_E6, 0,
  0, NOTE_A6, 0, NOTE_B6,
  0, NOTE_AS6, NOTE_A6, 0,

  NOTE_G6, NOTE_E7, NOTE_G7,
  NOTE_A7, 0, NOTE_F7, NOTE_G7,
  0, NOTE_E7, 0, NOTE_C7,
  NOTE_D7, NOTE_B6, 0, 0,

  NOTE_C7, 0, 0, NOTE_G6,
  0, 0, NOTE_E6, 0,
  0, NOTE_A6, 0, NOTE_B6,
  0, NOTE_AS6, NOTE_A6, 0,

  NOTE_G6, NOTE_E7, NOTE_G7,
  NOTE_A7, 0, NOTE_F7, NOTE_G7,
  0, NOTE_E7, 0, NOTE_C7,
  NOTE_D7, NOTE_B6, 0, 0
};
//Mario main them tempo
int tempo[] = {
  12, 12, 12, 12,
  12, 12, 12, 12,
  12, 12, 12, 12,
  12, 12, 12, 12,

  12, 12, 12, 12,
  12, 12, 12, 12,
  12, 12, 12, 12,
  12, 12, 12, 12,

  9, 9, 9,
  12, 12, 12, 12,
  12, 12, 12, 12,
  12, 12, 12, 12,

  12, 12, 12, 12,
  12, 12, 12, 12,
  12, 12, 12, 12,
  12, 12, 12, 12,

  9, 9, 9,
  12, 12, 12, 12,
  12, 12, 12, 12,
  12, 12, 12, 12,
};
//Underworld melody
int underworld_melody[] = {
  NOTE_C4, NOTE_C5, NOTE_A3, NOTE_A4,
  NOTE_AS3, NOTE_AS4, 0,
  0,
  NOTE_C4, NOTE_C5, NOTE_A3, NOTE_A4,
  NOTE_AS3, NOTE_AS4, 0,
  0,
  NOTE_F3, NOTE_F4, NOTE_D3, NOTE_D4,
  NOTE_DS3, NOTE_DS4, 0,
  0,
  NOTE_F3, NOTE_F4, NOTE_D3, NOTE_D4,
  NOTE_DS3, NOTE_DS4, 0,
  0, NOTE_DS4, NOTE_CS4, NOTE_D4,
  NOTE_CS4, NOTE_DS4,
  NOTE_DS4, NOTE_GS3,
  NOTE_G3, NOTE_CS4,
  NOTE_C4, NOTE_FS4, NOTE_F4, NOTE_E3, NOTE_AS4, NOTE_A4,
  NOTE_GS4, NOTE_DS4, NOTE_B3,
  NOTE_AS3, NOTE_A3, NOTE_GS3,
  0, 0, 0
};
//Underwolrd tempo
int underworld_tempo[] = {
  12, 12, 12, 12,
  12, 12, 6,
  3,
  12, 12, 12, 12,
  12, 12, 6,
  3,
  12, 12, 12, 12,
  12, 12, 6,
  3,
  12, 12, 12, 12,
  12, 12, 6,
  6, 18, 18, 18,
  6, 6,
  6, 6,
  6, 6,
  18, 18, 18, 18, 18, 18,
  10, 10, 10,
  10, 10, 10,
  3, 3, 3
};

void setup(void)
{
  pinMode(3, OUTPUT);//buzzer
  pinMode(13, OUTPUT);//led indicator when singing a note

}
void loop()
{
  //sing the tunes
  sing(1);
  sing(1);
  sing(2);
}
int song = 0;

void sing(int s) {
  // iterate over the notes of the melody:
  song = s;
  if (song == 2) {
    int size = sizeof(underworld_melody) / sizeof(int);
    for (int thisNote = 0; thisNote < size; thisNote++) {

      // to calculate the note duration, take one second
      // divided by the note type.
      //e.g. quarter note = 1000 / 4, eighth note = 1000/8, etc.
      int noteDuration = 1000 / underworld_tempo[thisNote];

      buzz(melodyPin, underworld_melody[thisNote], noteDuration);

      // to distinguish the notes, set a minimum time between them.
      // the note's duration + 30% seems to work well:
      int pauseBetweenNotes = noteDuration * 1.30;
      delay(pauseBetweenNotes);

      // stop the tone playing:
      buzz(melodyPin, 0, noteDuration);

    }

  } else {

 
    int size = sizeof(melody) / sizeof(int);
    for (int thisNote = 0; thisNote < size; thisNote++) {

      // to calculate the note duration, take one second
      // divided by the note type.
      //e.g. quarter note = 1000 / 4, eighth note = 1000/8, etc.
      int noteDuration = 1000 / tempo[thisNote];

      buzz(melodyPin, melody[thisNote], noteDuration);

      // to distinguish the notes, set a minimum time between them.
      // the note's duration + 30% seems to work well:
      int pauseBetweenNotes = noteDuration * 1.30;
      delay(pauseBetweenNotes);

      // stop the tone playing:
      buzz(melodyPin, 0, noteDuration);

    }
  }
}

void buzz(int targetPin, long frequency, long length) {
  digitalWrite(13, HIGH);
  long delayValue = 1000000 / frequency / 2; // calculate the delay value between transitions
  //// 1 second's worth of microseconds, divided by the frequency, then split in half since
  //// there are two phases to each cycle
  long numCycles = frequency * length / 1000; // calculate the number of cycles for proper timing
  //// multiply frequency, which is really cycles per second, by the number of seconds to
  //// get the total number of cycles to produce
  for (long i = 0; i < numCycles; i++) { // for the calculated length of time...
    digitalWrite(targetPin, HIGH); // write the buzzer pin high to push out the diaphram
    delayMicroseconds(delayValue); // wait for the calculated delay value
    digitalWrite(targetPin, LOW); // write the buzzer pin low to pull back the diaphram
    delayMicroseconds(delayValue); // wait again or the calculated delay value
  }
  digitalWrite(13, LOW);

}

RESULT

Considering that the audio board is entirely homemade, it sounds fairly excellent. We were able to operate it successfully after uploading the code into the XIAO and powering it externally using a USB cable

I have included a short clip that features a small audio track and the overall sound of the setup.

Furthermore, we connected the GND of a 3.5MM Audio Jack cable to the audio board's GND and the right channel pin of the audio Jack to the audio board's R-IN.

Then, we were able to use the smartphone with the 3.5mm audio jack. This audio board was functioning fairly well overall, indicating that it is prepared for use in the upcoming project.

What's Next?

We will be using this audio board in an upcoming Game Boy project as the next step or phase. This audio board will be used in that project to both supply power and output the audio produced by the Raspberry Pi. To obtain an audio signal, we will link the input pins of the audio board through the Raspberry Pi's GPIO.

Overall, this project is working and requires no further revisions.

Leave a comment if you need any help regarding this project. This is it for today, folks.

Thanks to Seeed Studio for supporting this project.

You guys can check them out if you need great PCB and stencil service for less cost and great quality.

And I'll be back with a new project pretty soon!