Hi,
I made a first protoype of the box (in carton paper), having both ir sensors as i wanted first. It is working, but not accurate enough.
So i built a second protoype (see picture attached), using the idea of the ramp.
I figured out that both ir sensors is front of each other is actually working as a beam break (2 beam breaks, as there are 2 sensors). So i only need to hide 1 sensor (the small piece of carton on the left), and it’s working really accurate.
Now the problem is that the ramp makes the piece falling slowlier, which is not good for the productivity of counting. So i’ll not consider the ramp anymore, meaning noto considering using a piezoelectric sensor anymore.
So i’ll come back to the 1st idea, but putting the 2 sensors in front of each other.
I’ll also try to had 2 more sesnors, to have a bigger surface to cover.
Let’s see how it will work 
Little by little we are getting to the final solution.
