>I'm interested in a device that can be used to count revolutions of a
>slow turning shaft, 10 turns/minute,  with 1 or 2 degree resolution.  I

How accessible, and what diameter is the shaft?

My thinking is you may get away with printing a single line graticule onto a
paper strip with a laser printer, and wrap this round the shaft. Then use a
reflective opto sensor to sense the lines going past. It is about the only
way to "add-on" a fine sensor unless you can add a rotation sensor to the
end of the shaft.

Just a thought after watching what was done to sense the position of a
linear piezo motor by the guys on the Star Tiger project
(http://www.startiger.org/ ). This was exactly how they did it, and it gave
them lines about 0.5mm thick with equal spaces. Good for a quick sensor :)

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