🚀 go-pugleaf

In article <mcmurtri-072F3E.12090107102002@typhoon.sonic.net>, Kevin McMurtrie <mcmurtri@sonic.net> wrote:
>In article <ans94t$moab$2@hades.csu.net>,
> Lizard Blizzard <NOSPAM@rsccd.org> wrote:
>
>>John Woodgate wrote:
>>[snip]
>>
>>> A good guide is that the string should
>>> not take up more than half the lowest supply voltage.
>>
>>That will guarantee that the dissipation in the resistors exceeds the 
>>LED dissipation.  In other words, the circuit is not power efficient.
>
>But this is for automotive power.
>
>Let's say you use 10V of LEDs.  Now the voltage drop will be between 
>1.5V and 6V with a normal of 4.5V.  You can't maintain good current 
>regulation with a simple resistor.  For 225 Ohms: 6mA min, 20mA normal, 
>27mA max.
>
>If you use 6V of LEDs, the voltage drop will be between 5.5V and 10V 
>with a normal of 8.5V.  A resistor is good enough here.  For 425 Ohms: 
>13mA min, 20mA normal, 24mA max.
>
>I imagine there's at least 4 amps to spare on the brake light line.

Why not just use a simple 8v or 10v voltage regulator ahead of the 
resistor? Then you can have the LEDs using most of the voltage, and the 
resistor will still have a relatively stable voltage across it, assuring 
constant current.

Chris