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    it (the thing to which the motor belongs) used to be battery powered, but i wanted it to run off the mains so i modified it, and now it has an adapter from the mains powering it.

    it works 'n all but the motor doesn't go round without being persuaded. it only starts if you give it a spin to get it going, after which it runs fine

    what could be the reason for this, and how can i fix it? i assume it's because the polarity isn't switching soon enough in the cycle, but i have no clue as to how i could have altered that with my modifications....
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    The voltage output from the power supply is probably too low.
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    yeah, make sure the voltage is the same as whatever battery you were running it off, and if possible try to provide the right current to match up with whatever power rating the motor has... some AC adaptors only provide 200mA or something
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    (Original post by JayEm)
    The voltage output from the power supply is probably too low.
    well it's a variable adapter that goes from 1.5 to 12 volts (300mA) and i've tried 'em all (previously it ran on 3xAAA)

    inside the motor there are.... hmmm picture better than words

    http://www.rccartips.com/motor-parts.jpg
    http://catalog.pitsco.com/sharedimag...or_cutaway.gif

    it's similar to that. the motor will get stuck at 0, 60, 120, 180... degrees of rotation if you get me... if you turn it round but don't let it spin of it's own accord it just sticks on each 1/6 of a rotation.

    i can't see how any more or less power will change it. it'll just stick with more force afaict.
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    sounds like some kind of stepper motor if it's sticking at specific angles (and not just 0 and 180)

    They're different from the ones you'd have done in school (where you have one coil, and two fixed magnets, and some sort of 'brush' type mechanism to reverse the current in the coil each half-rotation) and I'm not really an expert on them... beyond replicating the exact current and voltage produced by your AAAs I can't really suggest much for you to do. Presumably with 3xAAA you'd have had 4.5 volts (3x1.5V). Maybe that wikipedia article can be of help?
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    (Original post by alex-hs)
    sounds like some kind of stepper motor if it's sticking at specific angles (and not just 0 and 180)

    They're different from the ones you'd have done in school (where you have one coil, and two fixed magnets, and some sort of 'brush' type mechanism to reverse the current in the coil each half-rotation) and I'm not really an expert on them... beyond replicating the exact current and voltage produced by your AAAs I can't really suggest much for you to do. Presumably with 3xAAA you'd have had 4.5 volts (3x1.5V). Maybe that wikipedia article can be of help?
    nope, it's definitely got brushes, but it has 3 coils (like the first pic i posted)

    :confused:

    the only thing i can think is that the commutator is at the wrong angle?
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    well if it still runs ok off batteries I'd doubt it's that... tbh it's not really my field of expertise though, sorry!
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    ok ok, just tried it out and the 3xAAA does still work perfectly so....

    why exactly would it not work with the adapter? what can i do to make it work off the mains? can i beef up the power and still have it working?
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    What is this device exactly? Is the motor loaded? Is the motor driven directly from the DC supply or is there some control circuitry? Hard to diagnose without more information

    When you first switch on, the current is limited only by the resistance in the windings as the magnetic fields are set up, and current will decrease as it starts to turn. If you can't provide enough current to produce enough torque to start the motor then it will stick until you give it a helping hand.

    Measure the voltage across the motor while it is stalled, my suspicion is that it will be much lower than you expect and your power supply will have lost regulation. Don't leave it stalled for too long or you risk damaging the motor and your power supply.

    Try placing a big capacitor across your power supply and allow it to charge before switching the motor on.
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    (Original post by EdwardCurrent)
    What is this device exactly? Is the motor loaded? Is the motor driven directly from the DC supply or is there some control circuitry? Hard to diagnose without more information

    When you first switch on, the current is limited only by the resistance in the windings as the magnetic fields are set up, and current will decrease as it starts to turn. If you can't provide enough current to produce enough torque to start the motor then it will stick until you give it a helping hand.

    Measure the voltage across the motor while it is stalled, my suspicion is that it will be much lower than you expect and your power supply will have lost regulation. Don't leave it stalled for too long or you risk damaging the motor and your power supply.

    Try placing a big capacitor across your power supply and allow it to charge before switching the motor on.
    I second what this guy is saying. Motors depending on whether they're ac or Dc need to have considerations taken into account to function properly.

    Matt
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    it's a grinder for um.... herbs....



    that's literally all there is to it. there is a little blade attached to the motor, but it makes no difference whether it's on or off.
 
 
 
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