> Can anyone help: I'm looking for a circuit to be used to sense walls and
> solid objects with for a mobile robot. I though of using optics, but what
> will happen when you paint your
> walls black???
Sharp makes several stand-alone IR ranging modules that are great for
this sort of thing. Go to
http://www.acroname.com/robotics/parts/parts.html, at the bottom of the
page.

BTW, Acroname is a great source for robot parts...

Dave Johnson