Sound Level Detecting Circuit

[minhal]

Hi guys, im new to this website
I have been given a project in a 4 credit course to design an Analogue Sound level detecting circuit
I was thinking of maybe the output being designed as a series of LEDs connected in parallel with resistors in each branch so that as the sound increases, a condensation mic would produce a signal which would be amplified by an OpAmp and then fed to the LEDs which light up. More LEDs means a louder detected sound.
This is my first circuit laboratory course in university and im honestly starstruck.
Can someone please help me make the circuit design on LTspice?
Any help would be appreciated!

 

[rjenkinsgb]

I'd suggest something like this:

Low Noise Mic Preamp Using NE5534 IC | Circuit Diagram

This is a project of a low noise mic preamp with NE5534 IC. NE5534 is a low noise opamp IC manufactured in 8 pin dip package and designed to use in audio equipments and instruments.

www.circuitdiagram.org

Followed by something like this:

LED VU Meter circuit diagram and instructions

The circuit below uses two quad voltage comparators (LM339) to illuminate a series of 8 LEDs indicating volume level. Each of the 8 comparators is biased at increasing voltages set by the voltage divider so that the lower right LED comes on first when the input is about 400 millivolts or about...

www.hobby-circuits.com

The preamp brings the mic signal up to a reasonable level, then the VU meter circuit rectifies the audio and feeds it to the comparator inputs, which switch the appropriate LEDs depending on level.

I would also replace the simple diode rec at the input of the VU circuit with an active rectifier, something like this:

http://en.m.wikipedia.org/wiki/File:Op-Amp_Precision_Rectifier_(Improved).svg

You could use an NE5532 dual audio opamp for both the preamp and rectifier.


You will need to adapt some things and adjust gains, bias circuits, the levels of the comparators etc. - but that's where you need to start experimenting and calculating.

(It's not reasonable for someone else to do the whole project for you; help and advise is a different thing, as long as you put a reasonable effort in to it.)

 

[ronsimpson]

LED VU Meter using LM3914 and LM358
I think there are some problems with it but worth looking at.

 

[audioguru]

Sound levels and our hearing are logarithmic like an obsolete LM3915. An LM3914 is still made but it makes a linear voltmeter, it is not logarithmic.
I designed and made my Sound Level Indicator project 14 years ago and it has been working day and night nonstop. It uses an LM3915, a dual opamp and 3 transistors.