CDROM spindle motors really are stepper motors too

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There is no fundamental difference between what is called
a 'stepper motor'  and a 'brushless DC motor'.  Either can
'step' or 'run' according to the drive electronics. Both require
electronic drive circuits to rotate to a step or to spin.

A CDROM motor with 9 stator windings and a 12 pole rotor
(6N + 6S), although designed to spin a CD continously,
will behave like a 10 degree stepper motor - energising
the coil terminals  with DC in the  right sequence will result
in 36 different rotor positions.
Energising the coil terminals with DC quickly in the correct
sequence (ie. AC) will result in smooth rotation, just as
energising the coils in ANY stepper motor with the correct
phase and amplitude will result in smooth rotation.









Re: CDROM spindle motors really are stepper motors too
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OK CDs and DVDs all  use stepper motors.

geoff



Re: CDROM spindle motors really are stepper motors too

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Spindle motors won't  be called stepper motors in your
spare parts index....they will be labelled brushless DC motors..
I am just pointing out that from an engineering point of view,
they differ in detail, not in their fundamental operation.












 


Re: CDROM spindle motors really are stepper motors too
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You could say then that a motor is only a 'stepper motor' if it is used in
that configuration.

Like a Delivery Van is on ly a Delivery Van if the van is used in Delivery
Van configuration.

geoff



Re: CDROM spindle motors really are stepper motors too

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The general class is 'brushless DC motors'. As I have been pointing out,
if they are used for positioning they are called stepper motors. If they
spin, then they are usually just labelled 'brushless DC motors', but this is
misleading because if you just apply DC to them, they will NOT spin.
From an engineering point of view, they differ in detail, not in their
fundamental operation. A 'stepper' will rotate continously if it's coils are
driven in the correct sequence, and they can be very smooth when
compared to 'brush commutated DC motors', by the way.

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That is a bad analogy.



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Re: CDROM spindle motors really are stepper motors too
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 From http://en.wikipedia.org/wiki/Stepper_motor :

Stepper motors operate much differently from normal DC motors, which
rotate when voltage is applied to their terminals. Stepper motors, on
the other hand, effectively have multiple "toothed" electromagnets
arranged around a central gear-shaped piece of iron. The electromagnets
are energized by an external control circuit, such as a microcontroller.
To make the motor shaft turn, first one electromagnet is given power,
which makes the gear's teeth magnetically attracted to the
electromagnet's teeth. When the gear's teeth are thus aligned to the
first electromagnet, they are slightly offset from the next
electromagnet. So when the next electromagnet is turned on and the first
is turned off, the gear rotates slightly to align with the next one, and
from there the process is repeated. Each of those slight rotations is
called a "step." In that way, the motor can be turned a precise angle.



 From http://en.wikipedia.org/wiki/Internet_troll :

An Internet troll, or simply troll in Internet slang, is someone who
posts controversial and usually irrelevant or off-topic messages in an
online community, such as an online discussion forum or chat room, with
the intention of baiting other users into an emotional response or to
generally disrupt normal on-topic discussion.




Re: CDROM spindle motors really are stepper motors too

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Steppers operate exactly the same as 'brushless DC motors', which also
are different from 'normal DC motors' in that neither will rotate (continously)
when voltage is applied to their terminals.

If you actually have a close look at the link you quoted above,
http://en.wikipedia.org/wiki/Stepper_motor :
you will find a diagram of a stepper motor with 3 coils connected in delta,
for smooth rotation, which is the same configuration as most CDROM
9-pole spindle motors.


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Re: CDROM spindle motors really are stepper motors too
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Best thing to do is just KF him and forget he exists. Oh, don't quote
him either, it defeats the object of the killfile some of us have placed
him in.
--
Clint Sharp

Pommy Go Home !!!



**  FUCK OFF  HOME

  -   you festering pile of pommy shit.




...  Phil






Re: Pommy Go Home !!!

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Philthy, Off the meds - I can tell.
Some consolation is you're here causing a stink and not on aus.hi-fi for a
change.



Re: Pommy Go Home !!!
In message
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Please don't quote him, if you don't quote him I don't see his ranting.
Although I do like the idea that he's expending all that energy getting
angry and foaming at the mouth in vain.
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--
Clint Sharp

Re: Pommy Go Home !!!

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No quoting.  Normal Usenet reply.  Info too brief to snip.
Besides, how was I to know you had PA kill-filed?
If I knew that I'd be predicting the Lotto numbers - right?  :-)




Re: Pommy Go Home !!!
In message
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Yeah, I Know. Mind you, if you do get a vision on those numbers......
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--
Clint Sharp

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