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Old 01/12/2008, 07:24 AM   #12
BeanAnimal
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Join Date: Feb 2003
Location: Pittsburgh
Posts: 20,771
Exactly Kim. The audio is "always" on and there is a certain noise floor for present for EACH input. You need a simple audio level meter with 2 adjustments. 1) for noise floor, or in laymens terms to set the minimum peak that will trigger the light. and 2) a sensativity adjustment to tune the circuit to fit your needs. You are basically looking at a mV scale that will rise and fall with the presense or lack of audio.

As Kim mentioned, we can do this with an OP amp or two. However it may be easier to just adapt a simple VU meter design instead of trying to come up with your own circuit.

Elliot sound products is a great resource:
http://sound.westhost.com/project60.htm
Also if you email Rod he may be able to offer some advice.

http://www.free-electronic-circuits....vel-meter.html

http://www.4qdtec.com/avu.html

On this page: LED VU METER http://ourworld.compuserve.com/homep...tm#vumeter.gif


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