elec1 Posted January 11, 2007 Report Share Posted January 11, 2007 Hi everibody,Someone can help me to realize a circuit with three LM3915 and 30 leds, with an electret mic? :) Quote Link to comment Share on other sites More sharing options...
audioguru Posted January 11, 2007 Report Share Posted January 11, 2007 Hi Elec,Welcome to our forum. ;D90dB is a very wide range. A sound pressure of 30dB is extremely low and background sounds and noise from the electret microphone and its preamp are higher. Then add 90dB to the 30dB and you have 120dB which is extremely loud and will overload the electret microphone and its preamp.I made one with a 60dB range and only 50dB was usable due to background noise and noise from the electret microphone and its preamp. It needed the input offset voltage of the preamp IC carefully adjusted to a null.That is why my Sound Level Indicator project has a range of "only" 50dB. If my home is completely quiet and I hold my breath, its lowest LED turns off. Its highest LED lights when sounds are extremely loud. Quote Link to comment Share on other sites More sharing options...
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