> Even easier is to use a bunch of spring fingers to read the
> conduct/no conduction to a piece of PCB. No optical biasing issues.

That only works with gold contacts and they have to be debounced properly. Paper
tape does not have error correction ...
 
> Someone could probably write code to use a web cam to
> track the holes as they moved past a backlight.

Contrast is much better if they are pulled in front of a flat black platen, with
front light. The camera does not take kindly to direct light sources pointing
into it. Also the software to handle the output already exists, it is the same
as used with the scanner. Please see the bottom of my previous posting.

Peter P.



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