On 8/30/2010, Gene wrote >> > Guys, would you recommend some inexpensive encoder type hand controls? >> > I would like to control "speed override" with a rugged encoder type >> > rotary control. >> > > A thought that I have played with in my mind, and gone as far as to order a > few parts, is to use a more or less std small stepper motor with 12 or 24 > volt rated coils, as an encoder by feeding it to a pair of comparators > which should give a quadrature A& B output. I haven't worked out a 100% > reliable method of protecting the comparator inputs from the over-voltage a > fast spin of the knob on the motor shaft would feed them, nor have I worked > out the most reliable hysteresis feedback to prevent low level vibrations > and such from outputting spurious signals. But, based on the fact that the > average $3 stepper motor is also a heck of a good generator, I see no > reason why it couldn't be done. Gene:
I had what seemed a brilliant "aha" several years ago while idly spinning a stepper motor in my hands and feeling the detent-like resistance. Gee, it could almost be an electromagnetic encoder, I thought. My sense of discovery dimmed when I went Googling and discovered that only about a gazillion others had got there before me :-( Still, the advantage of being a johnny-come-lately is that I could profit from the experiences of others. I particularly liked the notion I came across of biasing a motor winding to improve the signal-to-noise ratio. I doubt I would have come up with that by myself. See, for example, http://www.piclist.com/techref/io/sensor/pos/enc/stepper_as_encoder.htm Regards, Kent PS - I got bogged down in family health crises and never got around to testing the approach and posting the results, at least not yet. Maybe someday. ------------------------------------------------------------------------------ Sell apps to millions through the Intel(R) Atom(Tm) Developer Program Be part of this innovative community and reach millions of netbook users worldwide. Take advantage of special opportunities to increase revenue and speed time-to-market. Join now, and jumpstart your future. http://p.sf.net/sfu/intel-atom-d2d _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
