In this article, we’ll walk through the steps to create a high-quality audio amplifier for home audio or DIY speaker projects using the TDA1905 integrated circuit (IC). The TDA1905 is a versatile power amplifier designed for driving speakers in audio applications, with a focus on providing reliable performance in consumer electronics, radios, and small audio systems. The project will guide you in using the TDA1905 to design an amplifier circuit capable of delivering clear and powerful sound to your audio setup.

Components Needed

1．TDA1905 Audio Power Amplifier IC

2．Capacitors (220nF, 1µF, 100µF, 10µF)

3．Resistors (1kΩ, 100Ω, 10kΩ)

4．Heat Sink for the TDA1905

5．Speaker (8Ω, typically)

6．Power Supply (12V or 15V, depending on the application)

7．PCB or Breadboard for mounting the components

8．Jumper wires and connectors

9．Diodes (1N4007 for protection)

10．Volume Potentiometer (10kΩ)

11．Input Capacitor (1µF)

12．Bypass Capacitor (100nF)

13．Thermal Paste (for heat sink mounting)

Introduction to the TDA1905

The TDA1905 is a medium power audio amplifier designed to drive speakers directly. It is commonly used in consumer audio devices, such as radios, television sets, and small public address systems. The chip is capable of delivering up to 14W of output power at a 12V supply with minimal external components, making it an excellent choice for DIY audio amplifier projects.

This amplifier is a Class AB amplifier, meaning it offers a good balance between sound quality and power efficiency. The TDA1905 has built-in protection circuits to prevent damage from overload, thermal shutdown, and short circuits, which makes it suitable for use in simple DIY projects.

Project Overview

In this project, we will create a simple stereo audio amplifier circuit using the TDA1905. The amplifier will be designed to drive an 8Ω speaker with a clean audio signal. The TDA1905 provides a good level of amplification with minimal distortion, making it ideal for driving a speaker from a low-voltage source, such as an audio output from a smartphone, audio player, or even a small microcontroller.

We will also integrate a volume control to adjust the output audio level. The circuit will include basic speaker protection from voltage spikes, noise filtering, and heat management to ensure safe and optimal operation.

Circuit Design

1. Input Stage and Volume Control

The input signal for this project could come from a variety of sources, such as a smartphone, a laptop, or a microcontroller with an audio output. The first stage of the circuit is the input stage, where the audio signal is fed into the amplifier.

We will use a 1µF capacitor to couple the audio signal, ensuring that no DC components are passed through to the amplifier. The capacitor blocks any DC voltage and only allows the AC audio signal to reach the amplifier.

For volume control, we’ll use a 10kΩ potentiometer. This will allow you to adjust the audio signal before it reaches the input of the TDA1905, enabling control over the output volume.

2. Amplifier IC: TDA1905

The core of this project is the TDA1905 power amplifier IC. The IC has an internal pre-amplifier and output stage, which significantly reduces the need for additional external components.

Here’s how the TDA1905 connects in the circuit:

1．Pin 1 (Input Pin): The audio signal enters the input of the IC through the potentiometer and coupling capacitor.

2．Pin 2 (Ground): This is the ground pin, which connects to the system’s ground.

3．Pin 3 (Output Pin): This pin drives the speaker. It provides the amplified audio signal to the speaker through a 220µF capacitor, which acts as a coupling capacitor to block DC voltage.

4．Pin 4 (Supply Pin): This pin is connected to the positive voltage rail, typically 12V or 15V depending on your design.

5．Pin 5 (Bias Pin): This pin is used to set the biasing for the internal stages of the IC. A 100nF bypass capacitor will be connected here to stabilize the voltage and reduce noise.

6．Pin 6 (Vcc Pin): This pin connects to the power supply, providing the necessary operating voltage for the amplifier.

The TDA1905 will automatically regulate the internal gain and output levels, making it easy to use with minimal external adjustments.

3. Output Stage and Speaker Connection

The TDA1905 is designed to drive speakers with an 8Ω impedance. The output is coupled with a 220µF capacitor to block any DC offset and ensure that only the AC audio signal reaches the speaker. The positive output from the IC is connected to one side of the speaker, and the other side of the speaker is connected to ground.

It’s important to use a good quality speaker that can handle the power output from the TDA1905. In our design, the power output will be sufficient to drive a small to medium-sized speaker at moderate volume levels.

4. Power Supply and Filtering

The TDA1905 requires a stable power supply to operate correctly. A 12V DC power supply will work well for this project, providing adequate power for the amplifier. The current draw will depend on the output power and speaker impedance but typically ranges from 2A to 3A.

We’ll use a 100µF capacitor on the power supply input to filter out any noise or ripples that could affect the performance of the amplifier. This capacitor will smooth the voltage and ensure the amplifier gets a clean, stable supply.

Additionally, we’ll include a 1N4007 diode across the power supply to protect the circuit from power surges and reverse voltage.

5. Heat Management

The TDA1905 has an integrated thermal shutdown feature, but it's still important to manage heat dissipation. We’ll attach a heat sink to the IC to help dissipate the heat generated during operation. Applying thermal paste between the IC and heat sink ensures better thermal contact and efficient heat transfer.

Assembly Instructions

Step 1: Prepare the Components

Gather all the components required for this project. Ensure you have the TDA1905 IC, capacitors, resistors, potentiometer, and speaker. Prepare your breadboard or PCB for assembly.

Step 2: Connect the Power Supply

Connect the 12V DC power supply to the Vcc pin (pin 6) of the TDA1905. Connect the ground of the power supply to the ground pin (pin 2) of the IC.

Step 3: Input Stage

1. Connect the input audio signal to one side of the 1µF capacitor.

2. Connect the other side of the capacitor to the input pin (pin 1) of the TDA1905.

3. Insert the 10kΩ potentiometer between the input signal and the IC, so you can control the volume of the audio signal.

Step 4: Output Stage

1. Connect the 220µF capacitor to the output pin (pin 3) of the TDA1905.

2. Connect the other side of the capacitor to one terminal of the 8Ω speaker.

3. Connect the other terminal of the speaker to the ground of the power supply.

Step 5: Power Filtering and Protection

1. Place a 100µF capacitor between the power supply's positive rail and ground to filter any power supply noise.

2. Attach the 1N4007 diode across the power supply pins for protection from voltage spikes or reverse voltage.

Step 6: Heat Sink Installation

1. Attach the heat sink to the TDA1905 IC to prevent overheating. Use thermal paste for better heat dissipation.

2. Ensure the heat sink has sufficient surface area to manage heat during continuous operation.

Step 7: Final Assembly and Testing

1. Double-check all connections and ensure the circuit is correctly wired.

2. Connect the 12V power supply and turn on the system.

3. Feed an audio signal into the input and use the potentiometer to control the volume.

4. Listen for clean, distortion-free sound through the speaker.

Troubleshooting Tips

1．No sound output: Check the power supply connections and ensure the IC is receiving the correct voltage. Verify that the input signal is connected properly and the potentiometer is functioning.

2．Distortion at high volumes: Ensure that the 220µF capacitor is correctly placed in series with the speaker and that the TDA1905 is not overheating.

3．IC overheating: Make sure the heat sink is properly installed. If the IC is still overheating, reduce the output power or improve ventilation around the amplifier.

Conclusion

This DIY audio amplifier project using the TDA1905 IC is an excellent choice for building a high-quality, medium-power audio amplifier. The TDA1905 provides easy-to-use, reliable amplification with minimal external components required. By following this simple design, you can create a solid audio amplifier suitable for a wide range of audio applications, from home speaker systems to portable audio setups.

With its built-in protection features and simple design, the TDA1905 is perfect for DIY enthusiasts looking to build a robust and efficient amplifier for audio projects. With proper heat management, filtering, and basic setup, this project can deliver clear and powerful sound with ease.