On Sun, 26 Dec 2010 01:17:12 -0600, G. Morgan wrote:

wrote:

From some recent work, a blue LED at about 5mA drops about
3V. At 20mA the drop is closer to 3.3V. Now, put thirty of these in a
string and the difference is 10V. You only have 20V across the
resistor - it's changed 50%. ...and this is quite nonlinear.

The resistor is a current regulator not a voltage regulator.

AN LED DOES NOT HAVE A VOLTAGE DROP, the voltage can only be
measured with a resistor in series with the DIODE. This is not a
lamp, incandescent, or CFL. It's a ****ing DIODE.

A resistor regulates nothing. R==V/I. If you say that I is constant
because V is constant and V is constant because I is constant, you're
getting nowhere. ;-).

Bull****, you pick resistor sizes based on how much current you
need/want. The R is fixed, thus so is the voltage drop. Are you
talking about a simulated dimmer like he suggested?

Perhaps you should read the thread. This time for comprehension.