The following diagram is the circuit diagram of 15W OTL power amplifier which is build based single amplifier chip TDA2030 produced by STMicroelectronics. This circuit is very simple, the main active component was the TDA2030 while the others discrete components supposed to support the TDA2030 to work properly.
15W OTL Power Amplifier Schematic Diagram:
15W OTL Power Amplifier PCB Layout
This is the video tutorial about how to build a realy simple headphone amplifier. The circuit powered with 9V battery and use an IC to amplify the input signal from mp3 player.
Watch the video: