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                   DiscoverCircuits.com -- Hobby Corner 
                  Last Updated on: 
                  
    Friday, December 29, 2017 05:52 AM 
                   
                  Hobby Circuits List 
                   
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                 More 
                Switch Circuits, 
                Micropower Circuits  | 
               
              
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                Audio Signal Detector/Switch Circuit 
                
                designed by David A. Johnson, P.E. 
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                For some audio systems it is desirable to have 
                an automatic switch circuit turn on other devices, such as an Amplifier, if an audio 
                signal is detected on one line.  The hobby circuit below will activate a 
                transistor switch when it detects at least 50mv peak to peak of an audio signal.   
                The switch could be used to turn on a relay, routing the signal to where it is 
                needed.  A single 3v lithium cell will power the electronic circuit for about 5 
                years. | 
               
             
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            Click on Drawing Below to view PDF version of Schematic  | 
           
          
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