Sound Level Meter

Sound Level Meter Circuit

Description

This is a one chip sound level meter that can be use for displaying sound level of an amplifier or simply the sound level from a microphone.The heart of the circuit is  IC LM 3915 Audio level IC.Even though it is a stand alone IC , a peak detector based on Transistor BC 558  and diode 1N4001  is also included for better performance.

Tips

Supply voltage  can be  from 3V to 20V.The input is set for  audio line voltage (1V peak to peak) and has a max  input voltage of 1.3V.   To make the circuit use a moving dot display instead of  bar graph display,Pin 9 can be should be disconnected from +V.

Parts List.

C1                            2.2uF 25V Electrolytic Capacitor
C2, C3                    0.1uF Ceramic Disc Capacitor
R1, R3                    1K 1/4W Resistor
R2                          10K 1/4W Resistor
R4                          100K 1/4W Resistor
R5                          1M 1/4W Resistor
D1                          1N4001 Silicon Diode
Q1                         BC 558 PNP Transistor
LED1-LED10       Standard LED or LED Array
U1                         LM3915 Audio Level IC
MISC                    Board, Wire, Socket For U1

Sound Level Meter Circuit Diagram.

Sound Level Meter Circuit/Acoustic Level Meter

Sound Level Meter

 

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4 Responses to “Sound Level Meter”

  • Carlos Senna says:

    I need to build a current level indicator with colors leds showing the current level. Seeing your circuit above I guess that maybe it could be adapted to my needs. So I ask you if you have a specific circuit to meet my needs or if you can give me directions to change this one to my needs.
    Thnks a lot

  • Chris says:

    Does it work with a PC. And if not, how sould I change it?

  • Murilo says:

    Hi Howre
    Try to connect 2 9v bateries in series. This IC needs more power to work fine.
    This circuit will work just for one channel. Chose left or right and connect it at the “input”. The ground must be connected to the ground of the circuit.
    Hope it is clear.

  • howry says:

    hey there, ive tried your way, but i have a huge problem!!! as i connect the “project” to 9v, only 7 of my leds work(which is stupid cause they are working great!) other thing is it does not react to sound!!! what could be the problem?
    and in this circuit, input ? what does it mean? cause in the input there is 3 ,ground left and right… what is the right way to connect them?