40W audio amplifier

john April 7, 2010 10 Comments

This is a very excellent 40W power amplifier design using TDA2030 IC and two transistors. The circuit employs only few components and does not require a dual power supply. The input signal is coupled to the non inverting input of TDA2030 through the DC decoupling capacitor C5. The TDA 2030 performs the major part of voltage amplification. As the IC performs amplification, the power supply current to the IC varies according to the input signal. The variations in the positive supply pin are coupled to the base of Q1 and variations in the negative supply pin are coupled to the base of Q2.The major part of current amplification is done by these two complementary transistors.

Circuit Diagram.



  • The circuit must be assembled on good quality PCB.
  • The PCB tracks through which there is high current flow should be made broader.
  • 12V to 40V can be used for powering the circuit. For maximum output, use 40V supply and 4 Ohms speaker.
  • Transistors and IC must be heatsinked.
  • Input and output grounds must be properly decoupled for optimum performance.

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