need a project idea on noise sensing

[rachna.sangwan86]

i want to make a major project on the idea of making a noise sensor for our library where an automatic announcement is made when the noise level rises upto preset value. kindly help.

 

[audioguru2]

One of these electronics chat forums had your question but I can't remember which one and when.

This site had a project that detects 3 different sound levels then lights an LED. You could build it with only one output to turn on your message machine and use a pot to set the sound level that activates it. I think it needs a diode added.
Then everybody in the library will laugh each time a motorcycle outside activates it.
The project is here: http://www.redcircuits.com/Page16.htm

 

[Keena]

hi..

is it possible that aside from the LED to be used, we can also add some audio into it??.. a programmed human voice giving the warning?? to be more recognized??

 

[audioguru2]

The circuit can turn on a transistor that can apply power to any electric circuit you want, including a voice player. Make sure that the microphone is muted or cannot hear the recording so it doesn't keep it playing over and over and over and ...

 

[Keena]

thanks..

i hope u can help me if ever we will try  this project..

 

[Hero999]

I designed a simple cirucit that will do this and posted it over on Electrotech Online but don't expect any help from me over there because the idiot administrator
banned me for disagreeing with him.

Fortunatley it can be found on the second Google hit:
http://www.google.co.uk/search?hl=en&client=opera&rls=en&q=electrotechonline+audio+light++Hero999&aq=f&aqi=&aql=&oq=&gs_rfai=
http://www.electro-tech-online.com/electronic-projects-design-ideas-reviews/106030-make-lights-flash-music-circuit-help-needed.html#post866658