1 Watt Audio Amplifier Circuit Diagram

Description

This amplifier was developed to be self-contained within a compact speaker enclosure. It can be powered by Walkmans, Mini-Discs, iPods, and CD players, alongside computers and similar devices possessing line or headphone outputs. Naturally, for stereo operation, two separate enclosures would generally be required.

Circuit Diagram:

Parts:

Circuit Operation:

The circuit was intentionally structured utilizing no integrated circuits and in a somewhat antiquated method to achieve favorable harmonic distortion characteristics and to circumvent the scarcity of certain components. The amplifier(s) can be conveniently supplied by a 12V wall-mounted adapter. Activating SW1 introduces a bass boost, concurrently necessitating an augmentation of the volume control to mitigate power loss at elevated frequencies. During operation, R9 ought to be meticulously adjusted to produce minimal perceptible signal crossover distortion aligned with minimal measured quiescent current consumption; a suitable compromise is to establish the quiescent current at approximately 10-15 mA. To measure this current, a DC current meter may be temporarily connected in series with the collector of Q3.

Integrated Circuits Description

The circuit incorporates several integrated circuits, each playing a vital role in its functionality. The BC560C, designated as Q1, is a general-purpose NPN transistor commonly employed in amplification applications. Its characteristics include a moderate gain and relatively high current handling capability, making it suitable for driving the loudspeaker. The BC337, designated as Q2, is another NPN transistor, known for its reliable performance and is often selected for its specific gain and current capabilities. Finally, the TIP31A and TIP32A, denoted as Q3 and Q4 respectively, are Darlington transistors. Darlington transistors are characterized by a very high current gain, making them suitable for driving loads that require significant current, such as a loudspeaker. They typically provide a more compact solution when high current demands exist.