I would like to design my projects/products so the ubiquitous ON indicator
LED is serving the secondary purpose of sending debug info serially, to a
phototransistor or some such which I have placed over it.  This would be
useful for development, but also for periodic sample testing of production
devices, don't you think?

I've found that spacing out the bytes, and sending at reasonably high data
rates results in a visibly steady LED glow (comm feature transparent).  My
problem is that I can't find phototransistors fast enough to switch fully
on and off with so little illumination (a few mA through a standard
brightness LED).

Yet it seems to me that this SHOULD work.  How about you smart folks who
have done this kind of thing a million times giving me the benefit of your
wisdom?

Bruce Cannon