![]() If you use a PWM (analogWrite()) signal to modulate the holding force you can adjust it to your liking. The amount of force it takes to move a stepper will depend on how much current is flowing. To understand people's answers, will a stepper motor allow itself to be rotated while active? To understand people's answers, will a stepper motor allow itself to be rotated while active? Is there a way to adjust how much torque would be required, so that it's the right amount that a person can do it (would gearing do the trick here?) And how, physically, would you attach a stepper motor to an encoder? I've seen this done with gears ( Converting a Stepper Motor to a Closed-loop Stepper Motor - Part 1 - YouTube ), is that the standard way to achieve this? It'd also be ideal for the motion to be stepped (is that the right word?) so that when moving it with your hand, it'd "click" through each second, rather than just smoothly rotating, but again that's a nice-to-have. Ideally, three hands with precision to 1/60th of a rotation, but two hands with precision to a 12th would be fine too. ![]() It would also help to know how many hands and how many positions for each hand. I guess it'd be a nice-to-have for the clock to have an actual time-keeping mode, but it's not a necessity. I should have made this clearer in the original post, but keeping accurate true time is actually a secondary priority.įor some context, an example use of this would be a game teaching kids to tell time with an analog clock, where either they have to set the hands to the time displayed on a screen, or type in the time which the hands have moved to. I was thinking standard kind of wall-clock size, but something like a desk-clock size would be okay too. Thanks for the ideas so far! To answer a few questions:įlexible on this. (You'd also need to gear-down if you wanted the movement to appear smooth.) ![]() The trickiest part might be the coaxial shaft.Ī standard stepper motor has 200 steps per revolution which doesn't divide evenly by 60, so that's the reason for gearing-down. If the software is continuously aware of the true-time, it can check for mechanical-home once per hour and make any required corrections (and/or it can correct before the hour is up, if mechanical-home comes too soon). Then, the clock will have to "find home" every time the software automatically re-sets it. Those will probably be some kind of optical sensors. The line frequency is very accurate and it's slowly adjusted /corrected over time so you'll get exactly the right number of cycles over a month or a year, etc., as long as there's no power outage.Įither way, if the computer/software has to know the mechanical position of the hands, you'll need home sensors (or least a home sensor for the minute-hand). Of course, commercial clocks don't have more than one motor.)ĪC clocks usually use a synchronous AC motor. (Or, a single motor if you can figure-out the mechanics. ![]() You probably want geared-down stepper motors. ![]()
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