> WR> LED's come in all sorts of voltage ratings, with different
 > WR> current ratings too.
 >
 >Eh?  Most of what I've seen is spec'd in the 1.6 - 1.8 volt range,  with
 >the exception of the stuff that's designed with a built-in current
 >limiter,  but that's not the same thing at all.
 >
 > WR> If wired in series (N of one hooked to P of the next, and so
 > WR> on) 3 volt LED's can have four across a 12 volt circuit.
 >
 >Where do you find 3 volt LEDs?  And what's going to limit the current in
 >that setup?  Have you ever seen the voltage vs. current curve of one of
 >those parts?  It's damn near a vertical line!
 WR> The intent was to show that there are different voltage/current 
 WR> combinations, and the original poster needs to pick the right 
 WR> one for his application. Generalized examples were given for 
 WR> series and parallel circuits. In a series circuit, the devices 
 WR> themselves will provide some current limiting. 
Oh no they won't!  Look at the voltage vs. current curve of any 
forward-biased semiconductor junction some time...
 WR> Increased current flow will decrease the voltage drop across 
 WR> them, causing the forward bias to decrease.  In the real world, 
 WR> if the devices are spec'd right, lead resistance combined with 
 WR> the voltage drops will limit current. 
I'm not really comfortable with that sort of a design,  counting on "lead 
resistance" and such to do the job,  not when even a small value resistor 
will do it much better for me.
 WR> Remember, the thread started with putting several LED's along 
 WR> baseboards, for inexpensive long lasting night lights in the 
 WR> hallways & elsewhere.
Yeah,  I remember how the thread started...
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