原文说明：
a step motor from an old floppy drive 5 1/4 inch disk can be used,
the two windings generate voltage when the motor is turned,
the pulse relations from the two windings is in perfect gray code,
but needs to be amplified and level converted to fit the 5 volt input level of the pic controller：
http://www.webx.dk/oz2cpu/20m/pic.htmthis type from a teac drive has 200 steps / revolution
has ball-barings and a super good feeling
note on the picture the small aluminium thing that was on the 5mm axle,
to remove it simply heat it up fast up to 150 c use wide screw driver to pull it off,
don't use force to pull it off, this will kill the ball-barings.
detail to mention here: the need for a big and heawy knob on the stepper axle,
becourse at slow turning the magnet will push and pull small and weak pulses,
some of them powerfull enough be seen on the output, this is removed totaly with a heawy knob.
also: both outputs will be at high state everytime the knob is standing still,
so the verry first low-pulse on output a or b, should be ignored in the software.
the whole floppy drive costed me under 1us$ at a ham marked !!
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