Hi Michael.

And what would be the benefit of connecting like that ?
( besides it's being described in every book how to handle LEDs :)

WBR Dmitriy.

PS. Olin already outlined that way.


michael brown wrote:
> 
> From: "Dmitriy Kiryashov"
> 
> > Hi Olin.
> >
> > CCP pin to base of NPN  ( 2N4401 or 2N2222 , Vcbo about 50v )
> > collector to +5v, emitter to current limiting resistor
> > 2nd pin of current limiting resistor to anode of LED
> > cathode of LED to ground
> >
> > One resistor less and smaller pcb estate.
> >
> > Any objections ?
> >
> >
> > WBR Dmitry.
> >
> > PS. 2N4401 with hFE = 50 on 100 mA sounds scary :)
> 
> With an NPN transistor (2n3904, 2n2222 etc), I'd connect the emitter to
> ground and the collector to the cathode of the LED.  The LED's anode
> should be connected to the dropping resistor and the other end of the
> resistor goes to Vcc.  IOW, I'd use it as a low side switch.  I'd
> probably use something like a 1K resistor to limit base current.
> 
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