Stereo Amplifier Using TDA2822

Project Overview:

This project presents a compact, low-power stereo amplifier based on the TDA2822M integrated circuit. The amplifier is designed to drive two 4-ohm, 1-watt speakers and is powered by a classic linear power supply unit. It's ideal for small DIY audio applications such as portable speaker systems, desktop audio, or embedded audio modules.

Background & History:

The TDA2822M is a popular dual audio amplifier IC introduced by STMicroelectronics. It's known for its simplicity, low cost, and suitability for battery-powered or small-scale audio projects. The chip supports both stereo and bridge configurations, with minimal external components required. This makes it a perfect candidate for learning and experimentation in analog audio electronics.

The project also incorporates a classic linear power supply (e.g., transformer, rectifier, capacitor filtering), offering a stable 15V DC source for the TDA2822M. Unlike switching power supplies, classic power supplies are favored for their low noise in sensitive analog circuits like audio amplification.

Main Features:

Amplification IC: TDA2822M (Dual-channel amplifier)

Input Source: Standard 3.5mm stereo audio (from AUX/PC/phone

Output: 2x 4Ω 1W speakers (Stereo Output)

Volume Control: Dual potentiometers (VR1 & VR2) for left/right channels

Power Supply: Classic 15V DC linear power supply (transformer + diode + filter caps)

Decoupling Capacitors: C1, C2, C3, C4 used for noise reduction and DC blocking

Compact Layout: Simple design with minimal parts, ideal for prototyping

How It Work

• Audio Input: The signal is received via a 3.5mm stereo jack and separated into left and right channels.
• Volume Control: Potentiometers (VR1 & VR2) adjust the amplitude of the incoming audio signals.
• Amplification: The signals are fed into the TDA2822M, which amplifies each channel separately (OUT1 and OUT2).
• Output Capacitors (C3, C4): These block any DC components before delivering the amplified signal to the speakers.
• Power Supply Filtering: Capacitors C1 and C2 stabilize the power supply and reduce ripple/noise.

Speakers: The LS1 and LS2 speakers reproduce the amplified signals as stereo sound.

Power Stage Description:

The classic power supply includes:

Step-down Transformer: Converts 230V AC to a safer low AC voltage.

Bridge Rectifier: Converts AC to pulsating DC.

Filter Capacitors (C1, C2): Smooth the pulsating DC into a stable DC voltage.

Regulation (if used): Optional voltage regulators (like 7803) may ensure a consistent 15V output.