Hi Ling,

You could use a microphone , operational amplifier with gain ,precision
rectifier with OPA, RC filter , log amplifier. Meter.
If you use a 4 Opa package like 324 it could be a small circuit.
Perhaps you could do it with a 8 pin PIC with A/D

Fernando

-----Original Message-----
From: V sml <decoder@BIGFOOT.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Date: Quarta-feira, 28 de Junho de 2000 8:06
Subject: [EE]: Sound level meter circuit?


>Hi all,
>
>I checked RS and Farnel cat., the meters are really expensive.  I just
>need a way to set the volume of 20 fixed public address output to
>level that customer accepted.
>
>Current method of setting at site is taking up too much time, and also
>too difficult because the room that holds the amplifier circuit cannot
>hear the speaker sound.
>
>I would like to do all settings in the lab, but I have to be sure that
>the level do not need to adjusted further when installed.  So I am
>thinking of capturing the dB from an installed set then go on to
>preset the rest in the lab.  I suppose if I put the sensor near to the
>speaker then the environment effects are reduced.
>
>Anyone has done it before? Comments? or have circuit of sound level
>meter that can interface to a dumb ascii terminal (so it is portable
>and I can use the 200lx or palm pilot)?
>
>Cheers, Ling SM
>