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Line busy indicator 

This circuit flashes an LED if the phone line is in use or is ringing. It is powered by the phone line, and it uses so little current that several of them could be used on the same line without interference. 

When first connected, let the circuit charge on an idle line for a couple minutes before expecting it to work. A high-brightness LED is recommended.

 Andrew R. Morris
morr3763@bellsouth.net

 

 
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