How to use a stepper motor with a normal battery instead of a driver and software

Discussion in 'DC Costumes and Props' started by Moviepropmaker6, Jul 11, 2015.

  1. Moviepropmaker6

    Moviepropmaker6 Active Member

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    Hi guys as most of you know i am making a motorised arkham knight cowl and i need to know how to use a stepper motor with anormal battery.normally you need a driver circuit board and an arsuino computer software.i need to know how to use a normal battery to make a unipolar stepper motor work
     
  2. MWiggs

    MWiggs Well-Known Member

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    I'm curious about this too for my own automated helmet. I've been looking into motors, servos, steppers, just about everything. Can't seem to come up with an ideal solution tho. Subbed!
     
  3. nomuse

    nomuse Sr Member RPF PREMIUM MEMBER

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    That's the problem -- a stepper is a stepper because it requires sequencing of the leads. That's what gives it the accurate positionability; the software drivers can count exactly how many times they've cycled through the different motor windings.

    Now, a servo is a slightly different beast; they are given a PWM signal (a square wave with a specified difference between the length of the positive and negative cycles) and they self-monitor; internal electronics built into the servo check the value of a potentiometer attached to the shaft and move the shaft until that value agrees with the value commanded by the input.

    Neither of these motors will do anything when connected to a simple DC voltage. The only motors that will move are regular DC motors. Which can be had in the form of gear-motors; aka a reduction gear train is already attached to the shaft and packaged conveniently into one housing. These can be controlled in speed as easily as by limiting the current, and controlled in position as easily as by putting limit switches into your circuit.
     
  4. maas101

    maas101 New Member

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    A battery just supplies the power for a stepper, to make the motor turn it needs the power to be switched to the control lines in a fixed sequence. It's possible to do with a couple of chips and a few ancillary components. PIC chips are ideal for this application coupled with a darlington driver. The following link shows a neat solution for controlling steppers with minimal components.

    http://www.rakeshmondal.info/USB-Stepper-Motor-Driver
     
  5. Moviepropmaker6

    Moviepropmaker6 Active Member

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    Thanks guys

    - - - Updated - - -

    Thanks alot
     
  6. juliegrrl

    juliegrrl New Member

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    As long as you don't need it to move more than 180 degrees or so a servo might be a good solution. There are quite a few components needed to build a servo driver, but you can run a single hobby servo directly from an arduino. You can pick up an arduino clone for less than 10 bucks and the wiring guide and library for running servos is one of the basic tutorials on arduino.cc. After just getting done building a second 3d printer I can say with some confidence that getting steppers to work requires a bit more effort, so unless you need the force that a stepper can provide I'd advise going the servo route.
    If all you need is a slow moving motor without the ability to accurately control it's movements a geared DC hobby motor might work, in which case you just wire it to a battery switch it on and switch it off.
     
  7. nomuse

    nomuse Sr Member RPF PREMIUM MEMBER

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    I pretty much argue for servo, too, but this is not because it is always the best solution, or even the best solution for this particular project, but because once you've gotten "over the hump" in software control, it adds a whole new tool to your prop-making.

    Yes -- for opening a visor a gear motor and a couple of limit switches will work quite well. In a way is even safer; you won't crash the prop if you have a software problem. (Otherwise known as micro snap action lever switches...a tiny switch with a metal feeler that will cut the power when the motor reaches the point where it should stop).

    And you can get very tricky with those thing; in the industrial world, there are controllers that ramp them up to full speed (instead of jerking into motion), go to several different positions on command, etc.

    But...you can also do stuff like this in software. It seems like using dynamite to fish; to put a whole micro-computer in just to run a motor. But the thing is, once you have that micro, you can ask it to handle a bunch of other things besides. Control the lighting, for instance. And once again; in the battery-and-switch world, you click a switch and the lights are on. Period. In software (or in more complex analog circuitry!) you merely tap a button and the lights fade up. A second tap, and they fade down.

    I'm doing a simple raygun right now, but I'm putting a micro in it; the micro will play back the sound effect, bring the LED to full intensity, hold it there for a moment, then fade it down; thus a complete "shot" takes place each time the trigger is touched. And by adding a potentiometer, I also have the ability to select other sounds/lighting, including a pulsating continuous beam mode.

    It is a bit to grasp. Even the really, really friendly Arduino platform can take you a long weekend to grok (it took me longer!) But I think it is a good skill to be thinking about adding for certain kinds of prop work.
     
  8. frizzen

    frizzen New Member

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  9. nomuse

    nomuse Sr Member RPF PREMIUM MEMBER

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    Just saw a new option for this; SparkFun has a servo controller board -- https://www.sparkfun.com/products/13118 -- For twenty bucks, it will take a switch or button and translate it into the commands to run a servo without any additional electronics. Three trim-pots on the board set the start point, end point, and traverse time.
     
    Wes R likes this.

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