Introduction: Building a Stereo Audio Amplifier Circuit With the TDA7297 Amplifier IC

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A Stereo Audio amplifier is a straightforward electronic circuit that elevates a low-power AC audio signal to a level capable of effectively driving an audio transducer, be it a headphone or loudspeaker. Audio amplifiers have firmly established their significance in contemporary electronics, whether applied in a simple toy or a complex music production setup. Consequently, in the present tutorial, we will meticulously explore the process of crafting a Stereo Audio Amplifier Circuit utilizing the TDA7297 Dual Bridge Amplifier IC.


At the core of this circuit resides the TDA7297 amplifier IC. The TDA7297 IC represents a stereo dual bridge amplifier, belonging to the Class AB category, offering dual channels for audio amplification. Housed within a conveniently compact 15-pin IC package, it exhibits operational compatibility within the voltage range of 6V to 18V, rendering it an apt choice for various consumer electronics applications such as TV, radio, and home theater systems. The TDA7297 IC possesses the capability to produce a substantial 30W (15+15) of output power, thereby enabling the simultaneous operation of two 4Ω speakers, each receiving 15W of power for achieving stereo audio excellence. For more details about TDA7297, you can read this article.

Supplies

  • TDA7297 Amplifier IC
  • Loudspeaker
  • Stereo Audio Amplifier PCB
  • Audio jack
  • LED
  • Diode
  • Capacitor
  • Potentiometer
  • Resistor
  • Soldering Iron
  • Soldering Wire with Flux
  • DC Battery
  • Battery Clips

Step 1: Design the PCB

To design the PCB using a PCB layout tool like EasyEDA and proceed to order the PCB via an online PCB fabrication service such as AllPCB.

Step 2: Solder All the Components on the PCB Board

Prepare Your Workspace:

Find a clean, well-ventilated area with ample lighting.

Set up your soldering station with a soldering iron, solder, soldering flux, and any necessary tools like wire cutters and tweezers.

Safety Precautions:

Wear safety goggles to protect your eyes from solder splatter.

Avoid inhaling solder fumes. If working in an enclosed space, use a fume extractor or ensure proper ventilation.

Component Placement:

Place all the components onto the PCB board according to your design or schematic.

Double-check the component values, orientations, and positions to ensure accuracy.

Soldering Process:

Begin with the smaller and low-profile components like resistors and capacitors.

Insert the component leads into the corresponding PCB pads.

Heat the soldering iron and apply a small amount of solder to the tip to ensure good thermal contact.

Soldering Technique:

Touch the soldering iron to both the component lead and the PCB pad simultaneously. The heat will melt the solder, creating a secure electrical and mechanical connection.

Ensure that the solder flows smoothly and forms a shiny, concave joint. Avoid creating solder bridges (unwanted connections between adjacent pads).

Trim Excess Leads:

After soldering each component, trim any excess component leads using wire cutters or flush cutters. Cut as close to the PCB as possible without damaging the joint.

Repeat the Process:

Continue soldering and trimming components in a systematic order, gradually moving to larger components such as integrated circuits (ICs) and connectors.

Special Components:

Pay extra attention when soldering sensitive components, such as ICs. Ensure correct orientation, and avoid excessive heat exposure to prevent damage.

Inspect Your Work:

After soldering all components, closely inspect the PCB for solder joints. Look for any solder bridges, cold solder joints (dull, grainy appearance), or other issues.

Use a magnifying glass if necessary for a detailed examination.

Testing:

Before applying power to the PCB, perform continuity and short-circuit checks using a multimeter to ensure there are no unintended connections.

Follow any specific testing procedures or guidelines relevant to your project.

Clean the PCB:

Remove any flux residues from the PCB using a suitable cleaning agent, if required.

Final Inspection:

Once you're confident that all solder joints are correctly made, and the PCB is clean and free from defects, your PCB assembly is complete.

Step 3: Connect the Terminals

To connect the +ve and -ve terminals of the two 4-ohm loudspeakers to the amplifier output through block connectors and attach a heat sink to the PCB board to reduce temperature.

Step 4: Connect the 3.5mm Audio Jack

To connect the 3.5mm audio jack to an audio source such as a smartphone, power up the circuit, and test it, follow these steps:

Prepare the 3.5mm Audio Jack:

  • Identify the terminals on the 3.5mm audio jack. Typically, it has three connections: left audio (L), right audio (R), and ground (GND).

Connect the Audio Jack:

  • Using appropriately sized wires, connect the L terminal of the 3.5mm audio jack to the left audio input on your amplifier's PCB.
  • Connect the R terminal of the audio jack to the right audio input on the PCB.
  • Connect the GND terminal of the audio jack to the ground (GND) on the PCB.

Power Up the Circuit:

  • Ensure the PCB is connected to a suitable power source, which could be a power supply unit or a battery, depending on your circuit design.
  • Power up the circuit by turning on the power source.

Test the Circuit:

  • Prepare an audio source, such as a smartphone, with a 3.5mm audio cable. Connect one end of the cable to the smartphone's audio output (usually the headphone jack).
  • Connect the other end of the audio cable to the 3.5mm audio jack you previously connected to the amplifier circuit.

Audio Playback:

  • Play an audio track or sound on your smartphone. The audio signal should now be transmitted from your smartphone to the amplifier through the 3.5mm audio jack.

Speaker Output:

  • Make sure the loudspeakers are correctly connected to the amplifier's output, as described in a previous step.

Volume Adjustment:

  • Gradually increase the volume on your smartphone to test the amplification capability of your circuit.
  • You should hear the audio output through the connected speakers. Make sure the volume is set to a reasonable level to avoid damaging the speakers or your hearing.

Audio Quality Check:

  • Listen to the audio output and check for sound quality, balance, and any distortion. If you encounter any issues, you may need to further inspect and fine-tune your circuit.



Operational Overview


This setup facilitates the processing of dual audio inputs and can deliver the audio output to a pair of distinct 15W 4 Ohm speakers. The operation of this arrangement unfolds as follows: Audio input sourced from a device, like a smartphone, is directed to the inverting inputs located at pins 4 and 12 of the TDA7297 IC. To ensure optimal signal transmission, two 220nF coupling capacitors are deployed to effectively isolate the DC component, permitting solely the AC component to pass through.

For sound output adjustments, this circuit incorporates the capability to modulate sound intensity. This is accomplished by manipulating the MUTE and ST-BY pins, achieved through a combination of a 10uF capacitor and a 50K potentiometer. The two 15W 4 Ohm speakers can be effortlessly linked to the dual outputs provided by the IC. Powering this circuit can be efficiently executed using a 12V battery.