How to build Mini Audio Analyzer

August 8, 2010 - category: Sound level meter


This analyst is, a sensitive instrument, in the frequency changes and width of a acoustic signal. Thus the brightness of LED that turns on each moment of is proportional signal width, while the colour of proportionally frequency. The circuit input sensitivity is regulated with R2, in order that in powerful signals they turn on the red LED, in the middle the yellow LED and in the low green LED. The display unit, is constituted by 3 lines of 10 LED the every, what is checked by a counter decoder (IC2). Two gates ICα-b, function as the IC2, with the R6 regulate the frequency. When does not exist signal in the input, then no one LED does not turn on. As soon as it will be applied signal, then the LED will begin to blink depending on the rythm and the intensity of signal. Can experiment with the prices of resistances R4, R5, so that you find the value that suits in like your. Initially it can they are placed trimmer 1KΩ, in the place of R4, R5 and after is found the suitable value, they are replaced with permanent resistances. What it wants it can it adds also other LED, adding other a completed same press with the IC2. The particular circuit does not have the claim, the precision of measurement input signal.

Circuit diagram

Circuit diagram

Parts list

  • R1= 1K8Kohm
  • R2= 100Kohm trimmer
  • R3= 1Kohm
  • R4= 100 ohm.....1Kohm
  • R5= 100 ohm.....1Kohm
  • R6= 100Kohm trimmer
  • C1= 100nF 100V
  • D1....10= RED LED
  • D11....20= YELLOW LED
  • D21....30= GREEN LED
  • IC1= LM3915
  • IC2= 4017
  • IC3= 4011

circuit from http://users.otenet.gr/~athsam/mini_audio_analyzer.htm

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