The circuit below is of a 15 Watts Class B audio amplifier circuit designed using a dual Op-amp and transistors.
The circuit shown here is of a simple Class-B audio amplifier based on opamp TL082, transistors TIP41 and TIP42. LM833 is a dual opamp with a high slew rate and low distortion particularly designed for audio applications. This audio amplifier circuit can deliver 15-watt audio output into an 8-ohm speaker at +12/-12V DC dual supply.
Both opamps in the IC are used here. IC1a is wired as a buffer and capacitor C3 does the job of input DC decoupling. Ic1b is wired in the inverting mode and it provides negative feedback. Complementary power transistors TIP41 and TIP42 are wired in the Class B push-pull scheme and they drive the loudspeaker. Diode D1 provides 0.7V bias voltage for the push-pull pair and capacitor C2 protects the 0.7V bias voltage across D1 from heavy voltage swings at the IC1b’s output.
Circuit diagram of Audio amplifier-15W
- The audio amplifier circuit must be assembled on a good quality PCB.
- Use a holder for mounting IC1.
- Use a +12/-12V dual supply for powering the amplifier.
- Potentiometer R2 can be used as a volume control.
- Raising the power supply voltage will increase the output power. Anyway, note the following points.
- TIP42 and 41 can handle only up to 6A.
- The maximum supply voltage IC1 can handle is +16/-16 V DC.
The audio amplifier’s configuration includes a transistor to handle input signals and a speaker for audio output. The arrangement of transistors is determined by specific requirements. When designing an audio amplifier, crucial factors to take into account are gain, noise, frequency response, and distortion. Increasing gain results in elevated distortion and noise levels, but the application of negative feedback can mitigate the amplifier’s gain.
The primary objective of audio amplifiers is to faithfully and efficiently replicate input audio signals at the sound-producing output components while maintaining desired volume and power levels, all with minimal distortion.