GM folks, I'm trying to find the 'proper' stuff to make a reflective opto quadrature rotary encoder. I'm having problems in as much as the black ( spirit based felt tip pen ) is reflecting as much IR as the white Please share your experience .. I'm using an old VCR head for the mechanics, with two OPB706a reflective opto couplers as the detectors. they are mounted inside the head assembly and shine on the inside of the VCR head which has a computer drawn wotzit ( can't think of its name ) stuck on the head. spaceing is about 1mm from opto's to wotzit. thanks v much mike -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics