Light Is On When Power Is Out

Abstract:AlossofACpowerduringdarkness(sensedbyaphotoresistor)turnsonanarrayofbattery-poweredwhiteLEDs.Toconservepower,atimerturnsofftheLEDsafteraparticularperiodoftime(forexample,10minutes).Maxim>AppNotes>AmplifierandComparatorCircuitsDisplayDriversKeywords:Emergencylighting,whiteLEDs,lightdetection,photoresistor,comparatorsFeb16,2005APPLICATIONNOTE3444LightIsOnWhenPowerIsOutAbstract:AlossofACpowerduringdarkness(sensedbyaphotoresistor)turnsonanarrayofbattery-poweredwhiteLEDs.Toconservepower,atimerturnsofftheLEDsafteraparticularperiodoftime(forexample,10minutes).Poweroutagescanoccurwhenleastexpected,leavingyouintotaldarkness.Whetherinahospital,atheater,oryourhome,suchoccasionscallforanemergencylightingsystemthatturnsonautomaticallywithlossofpower.ThepreferredemergencylightsourceisthewhiteLED,whichisgainingpopularityasacompact,power-