CDROM Spindle Stepper motor

[fritz]

geoff <geoff@nospam-paf.co.nz> wrote in message news:j6mdnSmgJdMeu7fVnZ2dnUVZ_tyknZ2d@giganews.com...

fritz wrote:
geoff <geoff@nospam-paf.co.nz> wrote in message
news:m_mdnXICIObeXLXVnZ2dnUVZ_obinZ2d@giganews.com...
fritz wrote:
Has anyone tried using a stepper motor from a CDROM ?

I have one, it was used to drive the spindle i.e. spin the disk
of a Sony CDROM.
It has 9 windings (coils) on the stator and 6 magnetic poles on the
rotor. (North poles only - 12 N+S in total)
The 9 stator windings are connected to only 3 terminals.

Stepper motor ?!!!

How would you servo control a stepper motor to track a CD pre-groove
?

geoff

Look up 'spindle'. i.e. it spins the disk
The motor I was talking about isn't part of the laser groove tracking
system at all.....

A stepper motor spinning the spindle - that doesn't sound very smooth !

Why not ?
Commmon stepper motors have 1,8 degree steps, while a typical
commutator DC motor has only 3 or 5 commutator segments being
discretely energised per revolution, is that any smoother ????
It all depends on the drive electronics, with the right timing a
'stepper motor' will be far smoother than a commutator motor.

I think you'll find it is a conventional brushless DC motor - not a stepper
motor.

geoff

You clearly do not understand the construction of these types of motor.
There is really fuck-all difference between what is called a 'stepper motor'
and what is called a 'brushless DC motor'.
Mechanically, they are virtually identical. The differences lie mostly in the
drive electronics for the application, and the way the stator coils are terminated.
The 'brushless DC motor' usually (but not always) has Hall-effect devices
mounted to sense the rotor position and control the phase of the (typically)
3-phase coil drivers, while 'Stepper motors' usually don't have rotor sensors.

Have a look at the May 2008 issue of Silicon Chip, page 16.
Leo Simpson argues that 'In reality, there is no such thing as a brushless
DC motor', and I totally agree that the terminology is misleading.

 

[fritz]

Clint Sharp <clint@clintsmc.demon.co.uk> wrote in message news:UZZ67pMX+pKIFwZn@clintsmc.demon.co.uk...

In message
482a5e0d$0$22170$5a62ac22@per-qv1-newsreader-01.iinet.net.au>, Bob
Parker <bobp.deletethis@bluebottle.com> writes
On 14/05/2008 09:37 geoff wrote:
A stepper motor spinning the spindle - that doesn't sound very
smooth !
I think you'll find it is a conventional brushless DC motor - not a
stepper motor.
geoff

Strange - that's exactly what I was thinking too. I always had the
idea that the disc rotates at a very constant velocity, which stepping
motors don't do.

CD-ROM spindle motors are generally brushless hall effect sensor types
(at least all the ones I've seen recently are) but isn't that just a
variant of stepper motor? Not trying to be argumentative, I'm just not
sure where the lines are drawn.

Correct.
Some people do not understand that there is no fundamental difference
between 'stepper motors' and ' brushless DC motors'. They both will move
to a fixed position and stop when their coils are driven by DC, to make them spin
continuously requires sequential coil drive, which is really AC not DC, isn't it ?

Have a look at the May 2008 issue of Silicon Chip, page 16.
Leo Simpson argues that 'In reality, there is no such thing as a brushless
DC motor', and I totally agree that the terminology is misleading.

Bob



--
Clint Sharp

 

[fritz]

geoff <geoff@nospam-paf.co.nz> wrote in message news:9tKdndQZbNAv_bbVnZ2dnUVZ_trinZ2d@giganews.com...

Clint Sharp wrote:
In message
482a5e0d$0$22170$5a62ac22@per-qv1-newsreader-01.iinet.net.au>, Bob
Parker <bobp.deletethis@bluebottle.com> writes
On 14/05/2008 09:37 geoff wrote:
A stepper motor spinning the spindle - that doesn't sound very
smooth !
I think you'll find it is a conventional brushless DC motor - not a
stepper motor.
geoff

Strange - that's exactly what I was thinking too. I always had the
idea that the disc rotates at a very constant velocity, which
stepping motors don't do.
CD-ROM spindle motors are generally brushless hall effect sensor types
(at least all the ones I've seen recently are) but isn't that just a
variant of stepper motor? Not trying to be argumentative, I'm just not
sure where the lines are drawn.

No. CD motors spin continuously.

Stepper motors action is to , surprising, step, one distinct step for every
driving pulse. Would not give a very nice clan smooth spin, even at high
speed.


geoff

WRONG !!!!

What makes you think a 'brushless DC motor' is any smoother than a
'stepper motor' ? How many poles does a 'brushless DC motor' have ?
What is the size of the 'step' for a 'brushless DC motor' (they don't
actually work with just DC, do they ?)
How many poles does a' stepper motor' have ?
Neither type has commutators, so any 'smoothness' is entirely due to the
design of the drive electronics, and is ultimately limited only by the number
of poles, isn't it ?

You clearly do not understand the construction of these types of motor.
There is really fuck-all difference between what is called a 'stepper motor'
and what is called a 'brushless DC motor'.
Mechanically, they are virtually identical. The differences lie mostly in the
drive electronics (for the application), and the way the stator coils are terminated.
A 'brushless DC motor' usually (but not always) has Hall-effect devices
mounted to sense the rotor position and control the phase of the (typically)
3-phase coil drivers, while 'Stepper motors' usually don't have rotor sensors,
but have more poles in the rotor.. ...

Have a look at the May 2008 issue of Silicon Chip, page 16.
Leo Simpson argues that 'In reality, there is no such thing as a brushless
DC motor', and I totally agree that the terminology is misleading.

 

[Phil Allison]

"fritz"

I think you'll find it is a conventional brushless DC motor - not a
stepper
motor.


You clearly do not understand the construction of these types of motor.

** You clearly are a narcissistic, nit picking idiot who cannot take being
corrected.

Brushless DC motors and stepper motors are the NOT the SAME - each type
is suited to particular applications and they have very different
characteristics.

See:

http://en.wikipedia.org/wiki/Brushless_DC_electric_motor

The see:

http://en.wikipedia.org/wiki/Stepper_motor

Have a look at the May 2008 issue of Silicon Chip, page 16.
Leo Simpson argues that 'In reality, there is no such thing as a brushless
DC motor', and I totally agree that the terminology is misleading.

** Completely irrelevant.



....... Phil

 

[geoff]

fritz wrote:


Why have you got 'steper motors' stuck in your 'brain' ?

CD players and CD-ROMs do NOT use stepper motors. None. Never.

geoff

 

[Bob Parker]

On 15/05/2008 11:30 geoff wrote:

fritz wrote:


Why have you got 'steper motors' stuck in your 'brain' ?

CD players and CD-ROMs do NOT use stepper motors. None. Never.

geoff

Thanks Geoff. I used to repair CD players which at that time mostly
used DC commutator spindle motors.
One of the most common problems was the commutator becoming slightly
erratic, causing increased rotational speed variations which caused the
data from the disc to overflow/underflow the buffer.
When you turn an unenergised stepper motor's shaft by hand, it jumps
from one magnetically-held step to the next. Normal motors move smoothly
and stop wherever you stop turning them.
Leo Simpson's a good bloke, but I kinda doubt that he's an expert on
the characteristics and applications of motors. Stepper motors and small
linear-rotation motors all have magnets and coils but they don't all
behave in the same way.

 

[Phil Allison]

"Bob Parker"

Leo Simpson's a good bloke,

** ??????????

but I kinda doubt that he's an expert on the characteristics and
applications of motors.

** All he said was that the name " Brushless DC " ( invented by the
Japanese as a marketing title ) is a * misnomer * - which it is. Cos they
are all really AC motors.

A better name might be " Electronically Commutated Motors " - but that
has no mass market appeal.

Stepper motors and small linear-rotation motors all have magnets and coils
but they don't all behave in the same way.

** For sure.


....... Phil

 

[Bob Parker]

On 15/05/2008 13:35 Phil Allison wrote:

"Bob Parker"

Leo Simpson's a good bloke,

** ??????????

Well he's been nice to me in the past.

** All he said was that the name " Brushless DC " ( invented by the
Japanese as a marketing title ) is a * misnomer * - which it is.

When I get a new SC I just skim through it for 15 minutes then give
it to a mate who collects them, so I don't even remember seeing anything
about motors (or anything much else in it).

Cos they are all really AC motors.

Exactly!

A better name might be " Electronically Commutated Motors " - but that
has no mass market appeal.

That's what I call them.

 

[Clint Sharp]

In message <6Z-dna1E4eoSD7bVnZ2dnUVZ_hSdnZ2d@giganews.com>, geoff
<geoff@nospam-paf.co.nz> writes

fritz wrote:


Why have you got 'steper motors' stuck in your 'brain' ?

CD players and CD-ROMs do NOT use stepper motors. None. Never.
Well, with respect Geoff, I have disassembled probably far too many and

an awful lot of them use a stepper to move the laser sled. As to the
definition of the spindle motor, I don't really see the difference
between a stepper and a brushless but I admit I'm not sure how you
define the two types to see the difference, maybe you can clarify that?

geoff

--
Clint Sharp

 

[geoff]

Clint Sharp wrote:

In message <6Z-dna1E4eoSD7bVnZ2dnUVZ_hSdnZ2d@giganews.com>, geoff
geoff@nospam-paf.co.nz> writes
fritz wrote:


Why have you got 'steper motors' stuck in your 'brain' ?

CD players and CD-ROMs do NOT use stepper motors. None. Never.
Well, with respect Geoff, I have disassembled probably far too many
and an awful lot of them use a stepper to move the laser sled. As to
the definition of the spindle motor, I don't really see the difference
between a stepper and a brushless but I admit I'm not sure how you
define the two types to see the difference, maybe you can clarify
that?

Are you sure ? How can a stepper motor, with it's "quantised' discrete
stepped positions track a continuous spiral groove ? My understanding is
that all CD spindle motors are servo-controlled , to enable accurate
tracking.

Could it be that people are not aware of what stepper-motors are. They are
NOT the same as a multi-pole DC motor, as the OP seems to think, from his
description ...


geoff

 

[fritz]

geoff <geoff@nospam-paf.co.nz> wrote in message news:RMmdnU8_MoLcLLHVnZ2dnUVZ_sninZ2d@giganews.com...

Clint Sharp wrote:
In message <6Z-dna1E4eoSD7bVnZ2dnUVZ_hSdnZ2d@giganews.com>, geoff
geoff@nospam-paf.co.nz> writes
fritz wrote:


Why have you got 'steper motors' stuck in your 'brain' ?

CD players and CD-ROMs do NOT use stepper motors. None. Never.
Well, with respect Geoff, I have disassembled probably far too many
and an awful lot of them use a stepper to move the laser sled. As to
the definition of the spindle motor, I don't really see the difference
between a stepper and a brushless but I admit I'm not sure how you
define the two types to see the difference, maybe you can clarify
that?


Are you sure ? How can a stepper motor, with it's "quantised' discrete
stepped positions track a continuous spiral groove ? My understanding is
that all CD spindle motors are servo-controlled , to enable accurate
tracking.

You don't understand what a spindle motor does, obviously.
It just spins the disk, it has nothing to do with the tracking of the laser, which I
have already explained. The spindle motor has feedback to spin the CD at
the right speed, usually with Hall effect sensors. The coarse tracking is controlled
by a separate motor with position feedback, and fine tracking is controlled with
a 'voice coil' suspension connected to the laser lens.

Could it be that people are not aware of what stepper-motors are. They are
NOT the same as a multi-pole DC motor, as the OP seems to think, from his
description ...

Actually they are very similar in construction and theory.
They both have a multi-pole rotor and a number of stator coils.
They both will move to fixed position and stay there when a coil is energised
by DC. To get either type to spin requires a controller to drive the coils
in the correct sequence. The main difference is the coil terminations, steppers
bring out all coils separately while so-called 'DC brushless' motors usually have
the coils connected in star or delta (for 3-phase types).

geoff

 

[fritz]

Phil Allison <philallison@tpg.com.au> wrote in message news:691fi8F2qg3jsU1@mid.individual.net...

"fritz"

I think you'll find it is a conventional brushless DC motor - not a
stepper
motor.


You clearly do not understand the construction of these types of motor.


** You clearly are a narcissistic, nit picking idiot who cannot take being
corrected.

ROTFLMFHO !!!
You are obviously describing yourself there, Philthy !!!!!

Brushless DC motors and stepper motors are the NOT the SAME - each type
is suited to particular applications and they have very different
characteristics.

They both have a multi-pole rotor and several stator coils, both will move
the rotor to a fixed position when a coil is energised by DC. They have far
more in common than you realise.

See:

http://en.wikipedia.org/wiki/Brushless_DC_electric_motor

QUOTES from YOUR link above :
'Brushless DC electric motor......'
'Two subtypes exist:
The stepper motor type may have more poles on the stator.
The reluctance motor. '

The see:

http://en.wikipedia.org/wiki/Stepper_motor

 

[Phil Allison]

"fritz the fuckhead "


** You clearly are a narcissistic, nit picking idiot who cannot take being
corrected.

Brushless DC motors and stepper motors are the NOT the SAME - each type
is suited to particular applications and they have very different
characteristics.

http://en.wikipedia.org/wiki/Brushless_DC_electric_motor




....... Phil

 

[Phil Allison]

" fritz the fuckhead "


** You clearly are a narcissistic, nit picking idiot who cannot take being
corrected.

Brushless DC motors and stepper motors are the NOT the SAME - each type
is suited to particular applications and they have very different
characteristics.

http://en.wikipedia.org/wiki/Brushless_DC_electric_motor


Then FOAD.


....... Phil

 

[fritz]

Phil Allison <philallison@tpg.com.au> wrote in message news:6940miF30ifl7U1@mid.individual.net...

"fritz the fuckhead "


** You clearly are a narcissistic, nit picking idiot who cannot take being
corrected.

Brushless DC motors and stepper motors are the NOT the SAME - each type
is suited to particular applications and they have very different
characteristics.

http://en.wikipedia.org/wiki/Brushless_DC_electric_motor

QUOTES from YOUR link above :
'Brushless DC electric motor......'
'Two subtypes exist:
The stepper motor type may have more poles on the stator.
The reluctance motor. '

 

[fritz]

Phil Allison <philallison@tpg.com.au> wrote in message news:6940qtF30vgsbU1@mid.individual.net...

" fritz the fuckhead "


** You clearly are a narcissistic, nit picking idiot who cannot take being
corrected.

Brushless DC motors and stepper motors are the NOT the SAME - each type
is suited to particular applications and they have very different
characteristics.

http://en.wikipedia.org/wiki/Brushless_DC_electric_motor

QUOTES from YOUR link above :

'Brushless DC electric motor......'
'Two subtypes exist:
The stepper motor type may have more poles on the stator.
The reluctance motor. '

 

[Phil Allison]

" fritz the ASD fucked fuckhead "


** You clearly are a narcissistic, nit picking idiot who cannot take being
corrected.

Brushless DC motors and stepper motors are the NOT the SAME - each type
is suited to particular applications and they have very different
characteristics.

http://en.wikipedia.org/wiki/Brushless_DC_electric_motor





....... Phil

 

[Phil Allison]

" fritz the ASD fucked fuckhead "


** You clearly are a narcissistic, nit picking idiot who cannot take being
corrected.

Brushless DC motors and stepper motors are the NOT the SAME - each type
is suited to particular applications and they have very different
characteristics.

http://en.wikipedia.org/wiki/Brushless_DC_electric_motor



Fuck off and Die - you MORON !!



....... Phil

 

[geoff]

fritz wrote:

You don't understand what a spindle motor does, obviously.
It just spins the disk, it has nothing to do with the tracking of the
laser, which I
have already explained. The spindle motor has feedback to spin the CD
at
the right speed, usually with Hall effect sensors. The coarse
tracking is controlled
by a separate motor with position feedback, and fine tracking is
controlled with
a 'voice coil' suspension connected to the laser lens.

Dude, I think I know eactly what a spindle motor does - I fix Denon, Sony,
and Nad ones every week and have don for decades. Also DVD and
DVD/CD-ROM/RWs.

None of these contain stepper motors, and I can't see how any other CD
could, given the pusly buzzy motion that a stepper can only supply. I have
never seen a CD with a spindle motor or a sled motor, that is a stepper. I
have seen stepper motors in telex machines,printers, and iindustrial process
machines.

Stepper motors move one discrete finite 'step' (surprisingly ?) for each
discrete DC pulse that is sent to drive it. All CD motors I have ever seen
are driven by a continuous DC, the voltage of which is finely varied to
control the speed of the spindle, or the position of the sled.

Grateful you specify which make/model CD contains a stepper motor.

by DC. To get either type to spin requires a controller to drive the
coils
in the correct sequence. The main difference is the coil
terminations, steppers
bring out all coils separately while so-called 'DC brushless' motors
usually have
the coils connected in star or delta (for 3-phase types).

So now you are trying to fudg the distinction between stepper motors and the
type you really mean. OK, I concede the I can therefore never 'win'.....


geoff

 

[geoff]

fritz wrote:

Phil Allison <philallison@tpg.com.au> wrote in message
news:6940qtF30vgsbU1@mid.individual.net...
" fritz the fuckhead "


** You clearly are a narcissistic, nit picking idiot who cannot take
being corrected.

Brushless DC motors and stepper motors are the NOT the SAME -
each type is suited to particular applications and they have very
different characteristics.

http://en.wikipedia.org/wiki/Brushless_DC_electric_motor

QUOTES from YOUR link above :
'Brushless DC electric motor......'
'Two subtypes exist:
The stepper motor type may have more poles on the stator.
The reluctance motor. '

Have you ever seen a CD drive with a stepper motor ?

geoff