> 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

        There is always the obvious: use an opto coupler with a
      visible light LED.

> 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.

      If the pattern is computer drawn, then there is little you can do
about it (what happened to the felt tip pen?). If your printer is a laser
printer, try using a dot matrix instead, otherwise, try vice-versa.

John Power

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