DVDdoug,
That was a nice post.
It's so frustrating to be so close to all the electronic goodies and just miss a little detail and know exactly too little. My first specs were for a stepper .. in chinese.
I have a handful of photo-interrupters and I can do without some .. I often feel better off without the specs and then 'try by error'. My setup worked before I popped this post .. and I realize now that a particular resistor on the test-circuit is a pull-up, so I do come out a little wiser.
I've started looking at a Hall sensor .. with plenty of info not strictly targeted at professionals. Now, thats a walk in the park (so far).
Thanks