From: *@eli.users.panix.com   
      
   In sci.electronics.basics, Ralph Mowery   wrote:   
   > 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.   
      
   About ten years ago I bought an LED candelabra bulb which lasted for   
   about five years before dying. I took it apart to see if I could figure   
   out what's wrong (mind you, I'm not an electronics wizard). The power   
   adapter part, which I suspected to be the problem, was turning out 150v   
   DC. The whole thing had a circuit even I could decipher. There was a   
   simple recifier with four diodes, two capacitors, and three resistors.   
   Inspection of the light board showed that it had all 20 (old-school T1   
   3/4 size through-hole soldered) LEDs in series. I suspect that one of   
   them failed, and that's what killed the whole.   
      
   I don't think they make LED bulbs like that any more. More recent bulbs   
   I've taken apart have been much different inside.   
      
   Elijah   
   ------   
   saved the LEDs but hasn't used them yet   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)