This 3 page article discusses building a simple audio amplifier circuit that can be powered by a 9V battery. It provides a detailed circuit diagram and instructions on selecting and connecting the components which include a transistor, resistors, capacitors and other basic electronic parts. The completed amplifier circuit is able to power a small speaker and amplify audio signals from a microphone or other audio source for listening or recording purposes.

1. Everyday Practical Electronics, Feb 1997 Copyright Wimbourne Publishing Ltd.
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