This circuit is a universal amplifier which can be used in many applications such as telephone amplifier, head-phone amplifier (mono), and general audio signal amplification. The circuit is based around the popular power amplifier IC LM386 capable of delivering 0.5W of audio power. The circuit's quiescent (stand-by) current consumption is under 10mA and is therefore ideal for battery operation. It's perfect for any of those projects that need an inexpensive and efficient amplifier that takes up minimal space. Due to its simplicity it is a great circuit for beginners and is very easy to assemble.