There are two sensors, that are positioned so their outputs change
alternately. The sequence then shows direction. In discrete logic it
takes about two quad logic chips to take the two outputs and produce a
direction. Essentially the two square waves are 90 waveform degrees
apart. Often for fine resolution the "holes" are more of a refraction
grid.
I know there's an explanation in my old IC-211 manual, ought to be one
on any of the web pages of rotary encoder makers, like Agilent.
73, Jerry, K0CQ
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Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.
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