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'[semiOT] Stepper as Sensor was(Best way to read '
|I like your idea. what did you observe the speed of turning needed to get a
definite pulse was? Will you always reliably get a good pair of pulses for
each movement from one stepper motor step to the next one at a time, or do
you need to keep it moving quickly? I am guessing the stepper's magnetic
snap action will give you a good pair of pulses each time with fingers
turing the shaft. If you connected one up to a thing to track by a cogged
rubber belt you would probably keep that snap action intact if the tension
is right and so get good pulses. the stepper's bearings could probably take
the tension necessary to be a good sensor without wearing too rapidly, then
you would need only one idler wheel at the other end of the belt, a link
from the belt to the thing to track, and a limit sensor to make a complete
linear position sensor that zero calibrates itself every time past the limit
John Griessen Austin TX cibolo.comjohn_g
Andrew Mayo wrote:
Very slowly indeed, like, even if you resist the cogging step as you
turn it, it still seems to work, though my simple transistor decoder
would need a little more gain. But the scope shows a definite pulse,
still, at reduced amplitude. A couple of op-amps would cope nicely, I
think. The quadrature is quite reliable, too, though you want to rely on
the phase relationship between edges and not assume that pulse widths
remain consistent with speed (they don't). But the edge relationships
are quite stable. You can use a monostable to create consistent pulse
widths if you wanted.
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