Finally, working on the bench, with Bobson's Ek box
(Thank you Bob for your patience!). The deep red LED is barely visible.. at 17mA current it is not much of a sight - because it emits very close to IR part of the spectrum...
What took so long were PCB's... not that they are complicated.. I combined them with some other projects I am involved with at my friend's company, and there were other priorities.. so I had to wait.
Today I managed to get hold of them and mounted two US Digital modules, and tried the whole thing with shiny strips, and it works.
The next step is proper encoder tape (printed on white paper) and experiment on my dobson..