Thursday, August 9, 2012

Notebook / Netbook Audio Amplifier

The audio output from a standart notebook or netbook with built-in speakers is low and the quality is also low. Alternatively, you can use a earphones to make good quality audio output, but for some people, earphones is unconfortable for them.

A power amplifier is needed to achieve a high volume. The following diagram is a simple circuit to amplify the notebook’s audio output.

The circuit is very simple and inexpensive, it use power amplifier IC LA4440 (IC1) and a few other components. LA4440 is a dual channel audio power amplifier, so you just need an IC for stereo application. It has low distortion over a wide range of low to high frequencies with good channel separation. Inbuilt dual channels enable it for stereo and bridge amplifier applications.

In dual mode LA4440 gives 6 watts per channel and in bridge mode 19- watt output. It has ripple rejection of 46 dB. The audio effect can be realized by using two 6-watt speakers. Connect pins 2, 6 and ground of IC1 to the stereo jack which is to be used with the notebook. Assemble the circuit on a general-purpose PCB and enclose in a proper case. The circuit is recommended to be powered using regulated 12V power supply to minimalize the noise or "hum" sound. It is recommended to use audio input socket in the circuit board. Mount the LA4440 on heatsink to prevent overheating on IC.

About Audio Amplifier
An audio amplifier is an electronic amplifier that amplifies low-power audio signals (signals composed primarily of frequencies between 20 - 20 000 Hz, the human range of hearing) to a level suitable for driving loudspeakers and is the final stage in a typical audio playback chain.
The preceding stages in such a chain are low power audio amplifiers which perform tasks like pre-amplification, equalization, tone control, mixing/effects, or audio sources like record players, CD players, and cassette players. Most audio amplifiers require these low-level inputs to adhere to line levels.
While the input signal to an audio amplifier may measure only a few hundred microwatts, its output may be tens, hundreds, or thousands of watts. More explanation about power audio amplifier can be found at
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:

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