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  • ChrisO138 commented on tdonoclift's instructable Hanging Gear Clock2 months ago
    Hanging Gear Clock

    Yeah, I was thinking about the reed switch after I posted, and remembered that it's difficult to control the precise trigger point with those. Ranges typically vary by about an inch, depending on various properties of the magnet and the approach angle, which wouldn't work well for "homing" a clock. I'm going to play around with an optical sensor and a hall-effect sensor. Given the small gap between the base of the clock and the moving parts, I believe that an optical sensor will be the easiest and will provide the highest level of precision.But then again... Back on the reed switch idea. With some simple tricks in software, the trigger and release positions could be calculated each time the trigger (magnet) passes the switch, and the mid-point should be acceptably close to the...

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    Yeah, I was thinking about the reed switch after I posted, and remembered that it's difficult to control the precise trigger point with those. Ranges typically vary by about an inch, depending on various properties of the magnet and the approach angle, which wouldn't work well for "homing" a clock. I'm going to play around with an optical sensor and a hall-effect sensor. Given the small gap between the base of the clock and the moving parts, I believe that an optical sensor will be the easiest and will provide the highest level of precision.But then again... Back on the reed switch idea. With some simple tricks in software, the trigger and release positions could be calculated each time the trigger (magnet) passes the switch, and the mid-point should be acceptably close to the middle of the switch. So, the calibration points could be known on each revolution, and a calibration could conceivably take place after each instance in which the trigger has left the area of affect and the reed switch re-opens.The main advantage of magnetic triggering is that the parts that perform the nerdery can remain hidden. It would be a shame to dork up this design by punching holes through it for sensors. You've done an unusually great job of hiding all of that in your design, so I'd be willing to bet that you're sensitive to that.Now if only I could be back at my shop.

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