You must have seen the live audio spectrum built-in low to high-end audio amplifier. Even a normal computer with built in sound card has it. How does sound wave produced relate with alternating bar graphs represent?
Sound wave is a continuous waveform. It can also be quantized into discrete levels of signal spectrum corresponds to the amplitude level.
Audio spectrum analyzer is a form of graphical display of the level of different frequency bands present in an audio signal. In order to tune for better sound quality, an accurate frequency response analyzer tool should be used.
There were two main audio spectrum analyzers available which are real time analyzer and non-real time analyzer.
Real time analyzer received input signal and concurrently split it into few adjacent frequency bands. In contrast, non-real time analyzer can only display a single tune-able filter and display a fixed frequency band up as needed.
The advantage of real time analyzer compared to non-real time analyzer is the average energy level of entire spectrum is sufficient to determine the separated display bands simultaneously. The only drawback of real time analyzer is about the cost.
In my small project, I will be making a small single spectrum audio analyzer with few components. The components used were:
- 1 x LM 3915/3916
Some information extracted from the datasheet of LM 3915.
- 1 x Resistor 1kOhm
- 1 x Trimmer/potentiometer 100kOhm.
- 1 x Capacitor 220uF (Optional)
- 4 x green LED
- 3 x amber LED
- 3 x red LED
- 1 x 3.5 mm audio jack with splitter
- 1 x Breadboard
- 1 x 6V or 9V battery
- 1 x Switch SPST/SPDT
The similar circuit is found from the datasheet, which displays the simplest application of the IC. The equation of obtaining the reference value is also shown.
A slight-modified and tested circuit is simulated with Proteus Design.
The actual hands-on circuit is assembled into breadboard.
I will upload the video on Youtube channel soon.
See you.
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