Here is a simple 5-watt mono audio amplifier using IC TA7222 that drives a 4-ohm speaker using a 9V battery or a 9V DC adaptor. You can also make a stereo amplifier by using two identical circuits.
Circuit and working of Mono Audio Amplifier
The schematic diagram of the 5-watt mono audio amplifier is depicted in Figure 1. In addition to the audio amplifier TA7222 (IC1) and a 4-ohm speaker (LS1), this 5-watt AF amplifier incorporates several resistors and capacitors, along with a potentiometer and two connectors.
IC TA7222 (IC1) serves as the core component of the circuit, featuring ten pins in total. Pin 1 is linked to the +9V power supply, with a 470µF, 25V capacitor (C1) bridging between +9V and the ground to function as a filter. Pins 2 and 3 of the IC remain unconnected. Pin 4 is tethered to the audio input terminal via potentiometer VR1, capacitor C2, and resistor R1. The potentiometer VR1 is employed for regulating the audio input signal.
Pin 5 of the IC connects to the ground through resistor R2 and capacitor C3. Pin 6 is not utilized. Pins 7 and 8 are grounded. A connection between pins 9 and 10 is established with the assistance of capacitor C4. Pin 9 links to the ground via capacitor C6 and is also coupled to the 4-ohm speaker (LS1) through capacitor C5.
Construction and testing
Upon circuit assembly, proceed with the calibration and adjustment process as outlined below: Attach a 9V battery to CON1 on the circuit. Connect a 4-ohm, 5-watt speaker to LS1. Next, carefully position the volume-control potentiometer (VR1) at its midpoint. Utilize a metal screwdriver to gently make contact with the audio input (CON2). You should be able to detect a humming sound emanating from the speaker. If this occurs, your amplifier is now prepared for operation.
After calibration, enclose the assembled PCB in a small plastic box.
1. This circuit can work with power supplies ranging from 6V to 12V DC.
2. Do not use a high-wattage soldering iron for IC1 as it can damage the IC. Use a suitable heat-sink to protect IC1 from overheating.