From: bretcahill@aol.com   
      
   > > The sealed-up-in-plastic power supply comes with the plug, 110v U.S. or   
   220v EU.    
   > >    
   > > On a 110 v AC U. S. plug the output appears to be 110 v DC and 220 AC on a   
   volt meter.    
   > >    
   > > The LED part of the rope light plugs into the output of the power supply.   
   It looks like two rails go the length of the LED section which can be cut   
   every meter at a marked location. Some LEDs can burn out while the others   
   remain lit. The LEDs are in    
   parallel.    
   > >    
   > > Do the LEDs run off the 220 AC or the 110 v DC?    
   > >    
   > > The connector from the adapter to the rope has an orientation indicating   
   it might be DC. If so is the 220 voltage just extraneous, part of a simple low   
   power rectification?    
   > >    
   > >    
   > >    
   > >    
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   > >   
   > Neither. The individual LEDs are around 1 to 3 volts depending on the    
   > led type. There is a resistor to limit the current through them.    
   >    
   > So comming down the rail on each side is a low voltage DC of around 12    
   > to 24 volts. Often a switching supply is used so the voltage is not a    
   > very good DC, but a DC with lots of ripple voltage. You can count the    
   > number of leds in a section and get an idea of the voltage.    
   >    
   > Usually each section will have a resistor and seveal leds in series.    
   >    
   > Leds are really current sensitive and not voltage . The led will take    
   > form 1 to 3 volts to start to light up. However if you do not limit the    
   > current the led burns up. So you put a few leds in series with a    
   > resistor and supply a few more volts than the leds require to light to    
   > the brightness desired.    
   >    
   > Leds operate on DC through them.   
      
   LEDs can operate on AC, it's just not quite 50% of the time.  Unless the   
   flashing is undesirable, rectification seems redundant.   
      
   Also, if the goal is DC, how does the 220v AC appear as a by product?     
      
   A lower extraneous AC voltage might make sense but a higher voltage?  That   
   seems intentional.   
      
      
   Bret Cahill   
      
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