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> Project: Audio Spectrum Analyzer
> Designed by: Abdullah M. Abdul-Hadi
> Date:
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Introduction:
A source of sound can have many different frequencies mixed together. Spectrum analysis is the technical process of decomposing a complex signal to many individual frequency components which mixed together to give that signal.
Decomposing any complex signal can be accomplished in real life by using filters. most of Audio spectrum analyzer in our cars used filter, especially Band Pass filter (BPF), which used to extract the single tone signals and display the analogue output on LED bar display or an LCD, in this project 3 bands had been built to give you an idea about how to build this device.
The Schematic Diagram:
As you can see in Fig.(1), the circuit contain many stages:
- The first stage that is starting with MIC to pick up the voice and low voltage audio power amplifier to amplify the input voice.
Fig.(1)
- The second stages contain a 3 band pass filters with different center frequency, the first fo=3KHZ, the second fo=5KHZ, and the third fo=8KHZ.
- The third stages contain a 3 bar display driver that senses the analogue voltage levels ( The outputs of band pass filters) and drive 10 LEDs, providing a linear analogue display.
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