Using TDA2030 integrated circuit, some power transistor and few passive electronic components can be made a very simple audio power amplifier.
This TDA2030 audio amplifier can deliver a maximum output power of about 40W on a 4-ohm load.
The audio signal is applied to the noninverting input of the TDA2030 integrated amplifier IC1.
IC1's supply current varies according to the input signal. Consequently, there is a similar variation of the voltage across resistors R6, R7, R8 and R9, as they are placed on the supply lines of the AO. While the current is less than 1A, voltage drop resistor is insufficient to open transistors T1 and T2. This means that the 2W output power in 4 ohms is entirely provided by the integrated circuit. When the output current exceeds 1A, transistors open and contribute to power output.
Voltage must be between 12 V and a maximum of 44 V.