Wednesday, August 5, 2009

Audio Level Meter with 8 LEDs Indicator

This audio level meter required 2 pieces of LM324 for each channel. Every single LM324 contain 4 op-amps, then you need 2 pieces of LM324 to cover 8 LEDs. And need 4 piece of LM324 for 16 LEDs (for stereo channel)
Here the schematic:
Audio Level Meter with 8 LEDs Indicator circuit diagram

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 a video tutorial about how to a very simple audio amplifier based on the LM386 amplifier chip. It can be built for less than $20 (or might be less than $8 in some countries) and used to amplify any low level audio signal including a guitar, bass or mp3 player.

Watch the video:

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