Dimming LED's *can* be done by just PWMing the device.  How about if I have=
 3 or 4 LED's in a string.....ie...constant voltage setup vs constant curre=
nt....seems reasonable that I can PWM the base of a transistor (assuming it=
 can sink 20mA) and it should do the same thing....dim the LED's that are i=
n series.   And of course, since the PWM dims them by rapidly turning them =
on and off...this should also conserve power as well....
   =

  So, if that is true....I'd need some sort of SEPIC convertor since its ru=
nning on batteries, to keep the voltage constant, and would be even better =
if the SEPIC could be PWMed rather than the string, but how fast can a typi=
cal SEPIC actually turn on and off?  Better to just stick with the transist=
or approach maybe...?
   =

  thoughts or comments?

 		=

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