Guest
I took apart an old inkjet printer and was surprised the stepper motor has such resistance to it, if it's just an iron gear rotor. What gives?
Guest
On Friday, May 13, 2016 at 7:35:17 PM UTC-7, mrda...@gmail.com wrote:
Never mind, I think I figured it out. It's got a permanent magnet for a rotor. (?!)
This is the exact one.
http://www.eminebea.com/en/product/rotary/steppingmotor/pm/standard/pm35s-048.shtml
Michael
Never mind, I think I figured it out. It's got a permanent magnet for a rotor. (?!)
This is the exact one.
http://www.eminebea.com/en/product/rotary/steppingmotor/pm/standard/pm35s-048.shtml
Michael
J
Jasen Betts
Guest
On 2016-05-14, mrdarrett@gmail.com <mrdarrett@gmail.com> wrote:
yeah, they're steppers, not switched reluctance.
--
\_(ă)_
yeah, they're steppers, not switched reluctance.
--
\_(ă)_
Guest
On Saturday, May 14, 2016 at 12:02:39 AM UTC-7, Jasen Betts wrote:
The search for a cheap reluctance motor continues.
What's the difference between variable and switched reluctance, anyway?
Michael
The search for a cheap reluctance motor continues.
What's the difference between variable and switched reluctance, anyway?
Michael
Guest
On Saturday, May 14, 2016 at 12:39:47 PM UTC-7, John Larkin wrote:
Oh nice!
And to think, I thought the resistance was due to precision micrometer spacing between the (reluctance) rotor and stator, such that air was having a hard time getting out of the way
Michael
Oh nice!
And to think, I thought the resistance was due to precision micrometer spacing between the (reluctance) rotor and stator, such that air was having a hard time getting out of the way
Michael
J
John Larkin
Guest
On Fri, 13 May 2016 19:35:13 -0700 (PDT), mrdarrett@gmail.com wrote:
>I took apart an old inkjet printer and was surprised the stepper motor has such resistance to it, if it's just an iron gear rotor. What gives?
It's even harder if you short the leads.
They make pretty good AC generators and speed sensors. Or, with a cap,
an AC-powered synchronous motor.
--
John Larkin Highland Technology, Inc
lunatic fringe electronics
>I took apart an old inkjet printer and was surprised the stepper motor has such resistance to it, if it's just an iron gear rotor. What gives?
It's even harder if you short the leads.
They make pretty good AC generators and speed sensors. Or, with a cap,
an AC-powered synchronous motor.
--
John Larkin Highland Technology, Inc
lunatic fringe electronics
J
John Larkin
Guest
On 14 May 2016 06:46:09 GMT, Jasen Betts <jasen@xnet.co.nz> wrote:
There are/were some VR steppers, but not as common as PM types.
--
John Larkin Highland Technology, Inc
lunatic fringe electronics
There are/were some VR steppers, but not as common as PM types.
--
John Larkin Highland Technology, Inc
lunatic fringe electronics
J
Jasen Betts
Guest
On 2016-05-14, mrdarrett@gmail.com <mrdarrett@gmail.com> wrote:
just me using the wrong word
If you can disassemble and reassemble them easily, possilby you could
put a laser-cut steel rotor in there to make a variable reluctance
motor.
--
\_(ă)_
On Saturday, May 14, 2016 at 12:02:39 AM UTC-7, Jasen Betts wrote:
On 2016-05-14, mrdarrett@gmail.com <mrdarrett@gmail.com> wrote:
On Friday, May 13, 2016 at 7:35:17 PM UTC-7, mrda...@gmail.com wrote:
I took apart an old inkjet printer and was surprised the stepper motor has such resistance to it, if it's just an iron gear rotor. What gives?
Never mind, I think I figured it out. It's got a permanent magnet for a rotor. (?!)
yeah, they're steppers, not switched reluctance.
The search for a cheap reluctance motor continues.
What's the difference between variable and switched reluctance, anyway?
just me using the wrong word
If you can disassemble and reassemble them easily, possilby you could
put a laser-cut steel rotor in there to make a variable reluctance
motor.
--
\_(ă)_
Guest
On Saturday, May 14, 2016 at 6:59:51 PM UTC-7, Tim Wescott wrote:
Ahh, ok.
But, if precise motion is not required, a brushless DC motor would be more efficient than a stepper, right?
Yep, it looks like I'll have to wind my own reluctance motor. I just wanted to study how a real one is made. Why would they laminate the iron rotor...? Is laminating the stator coils recommended too?
Thanks,
Michael
On Sat, 14 May 2016 09:54:08 -0700, mrdarrett wrote:
On Saturday, May 14, 2016 at 12:02:39 AM UTC-7, Jasen Betts wrote:
On 2016-05-14, mrdarrett@gmail.com <mrdarrett@gmail.com> wrote:
On Friday, May 13, 2016 at 7:35:17 PM UTC-7, mrda...@gmail.com wrote:
I took apart an old inkjet printer and was surprised the stepper
motor has such resistance to it, if it's just an iron gear rotor.
What gives?
Never mind, I think I figured it out. It's got a permanent magnet
for a rotor. (?!)
yeah, they're steppers, not switched reluctance.
--
\_(ă)_
The search for a cheap reluctance motor continues.
snip
PM steppers actually do have variable reluctance magnetic paths -- that's
why they have favored positions when they're powered down.
Basically, when you have a magnetic path, the magnetic attraction is in
the direction that reduces the reluctance of the path and takes the most
energy out of the magnetic circuit. With a magnetic circuit "powered" by
a permanent magnet, this energy comes out of the magnet (and is returned
when you pull things apart). With a variable reluctance motor, this
energy comes out of motor's source of current.
If you just want to do a science experiment with reluctance motors, you
could make one by hand -- a soft iron bar or ferrite on a shaft and a
pair of coils should give you something that will spin if you treat it
right.
--
Tim Wescott
Control systems, embedded software and circuit design
I'm looking for work! See my website if you're interested
http://www.wescottdesign.com
Ahh, ok.
But, if precise motion is not required, a brushless DC motor would be more efficient than a stepper, right?
Yep, it looks like I'll have to wind my own reluctance motor. I just wanted to study how a real one is made. Why would they laminate the iron rotor...? Is laminating the stator coils recommended too?
Thanks,
Michael
Guest
On Saturday, May 14, 2016 at 7:20:21 PM UTC-7, Tim Wescott wrote:
On that note, is this a reasonable low-power 3-phase circuit?
http://www.homemade-circuits.com/2014/12/3-phase-signal-generator-using.html
Maybe I'll replace the transistors with PN2222s which can take about 1 amp.
Thanks,
Michael
On Sat, 14 May 2016 20:59:48 -0500, Tim Wescott wrote:
On Sat, 14 May 2016 09:54:08 -0700, mrdarrett wrote:
On Saturday, May 14, 2016 at 12:02:39 AM UTC-7, Jasen Betts wrote:
On 2016-05-14, mrdarrett@gmail.com <mrdarrett@gmail.com> wrote:
On Friday, May 13, 2016 at 7:35:17 PM UTC-7, mrda...@gmail.com
wrote:
I took apart an old inkjet printer and was surprised the stepper
motor has such resistance to it, if it's just an iron gear rotor.
What gives?
Never mind, I think I figured it out. It's got a permanent magnet
for a rotor. (?!)
yeah, they're steppers, not switched reluctance.
--
\_(ă)_
The search for a cheap reluctance motor continues.
snip
PM steppers actually do have variable reluctance magnetic paths --
that's why they have favored positions when they're powered down.
Basically, when you have a magnetic path, the magnetic attraction is in
the direction that reduces the reluctance of the path and takes the most
energy out of the magnetic circuit. With a magnetic circuit "powered"
by a permanent magnet, this energy comes out of the magnet (and is
returned when you pull things apart). With a variable reluctance motor,
this energy comes out of motor's source of current.
If you just want to do a science experiment with reluctance motors, you
could make one by hand -- a soft iron bar or ferrite on a shaft and a
pair of coils should give you something that will spin if you treat it
right.
Oops -- I think you need at least three independent coils if there's not
a magnet involved. But you may know more than me at this point.
--
Tim Wescott
Control systems, embedded software and circuit design
I'm looking for work! See my website if you're interested
http://www.wescottdesign.com
On that note, is this a reasonable low-power 3-phase circuit?
http://www.homemade-circuits.com/2014/12/3-phase-signal-generator-using.html
Maybe I'll replace the transistors with PN2222s which can take about 1 amp.
Thanks,
Michael
Guest
Why, increased cost?
J
John Larkin
Guest
On Sat, 14 May 2016 15:07:07 -0700 (PDT), mrdarrett@gmail.com wrote:
In an inkjet printer?
--
John Larkin Highland Technology, Inc
lunatic fringe electronics
On Saturday, May 14, 2016 at 12:39:47 PM UTC-7, John Larkin wrote:
On Fri, 13 May 2016 19:35:13 -0700 (PDT), mrdarrett@gmail.com wrote:
I took apart an old inkjet printer and was surprised the stepper motor has such resistance to it, if it's just an iron gear rotor. What gives?
It's even harder if you short the leads.
They make pretty good AC generators and speed sensors. Or, with a cap,
an AC-powered synchronous motor.
--
John Larkin Highland Technology, Inc
lunatic fringe electronics
Oh nice!
And to think, I thought the resistance was due to precision micrometer spacing between the (reluctance) rotor and stator, such that air was having a hard time getting out of the way
Michael
In an inkjet printer?
--
John Larkin Highland Technology, Inc
lunatic fringe electronics
T
Tim Wescott
Guest
On Sat, 14 May 2016 20:59:48 -0500, Tim Wescott wrote:
Oops -- I think you need at least three independent coils if there's not
a magnet involved. But you may know more than me at this point.
--
Tim Wescott
Control systems, embedded software and circuit design
I'm looking for work! See my website if you're interested
http://www.wescottdesign.com
On Sat, 14 May 2016 09:54:08 -0700, mrdarrett wrote:
On Saturday, May 14, 2016 at 12:02:39 AM UTC-7, Jasen Betts wrote:
On 2016-05-14, mrdarrett@gmail.com <mrdarrett@gmail.com> wrote:
On Friday, May 13, 2016 at 7:35:17 PM UTC-7, mrda...@gmail.com
wrote:
I took apart an old inkjet printer and was surprised the stepper
motor has such resistance to it, if it's just an iron gear rotor.
What gives?
Never mind, I think I figured it out. It's got a permanent magnet
for a rotor. (?!)
yeah, they're steppers, not switched reluctance.
--
\_(ă)_
The search for a cheap reluctance motor continues.
snip
PM steppers actually do have variable reluctance magnetic paths --
that's why they have favored positions when they're powered down.
Basically, when you have a magnetic path, the magnetic attraction is in
the direction that reduces the reluctance of the path and takes the most
energy out of the magnetic circuit. With a magnetic circuit "powered"
by a permanent magnet, this energy comes out of the magnet (and is
returned when you pull things apart). With a variable reluctance motor,
this energy comes out of motor's source of current.
If you just want to do a science experiment with reluctance motors, you
could make one by hand -- a soft iron bar or ferrite on a shaft and a
pair of coils should give you something that will spin if you treat it
right.
Oops -- I think you need at least three independent coils if there's not
a magnet involved. But you may know more than me at this point.
--
Tim Wescott
Control systems, embedded software and circuit design
I'm looking for work! See my website if you're interested
http://www.wescottdesign.com
T
Tim Wescott
Guest
On Sat, 14 May 2016 09:54:08 -0700, mrdarrett wrote:
<snip>
PM steppers actually do have variable reluctance magnetic paths -- that's
why they have favored positions when they're powered down.
Basically, when you have a magnetic path, the magnetic attraction is in
the direction that reduces the reluctance of the path and takes the most
energy out of the magnetic circuit. With a magnetic circuit "powered" by
a permanent magnet, this energy comes out of the magnet (and is returned
when you pull things apart). With a variable reluctance motor, this
energy comes out of motor's source of current.
If you just want to do a science experiment with reluctance motors, you
could make one by hand -- a soft iron bar or ferrite on a shaft and a
pair of coils should give you something that will spin if you treat it
right.
--
Tim Wescott
Control systems, embedded software and circuit design
I'm looking for work! See my website if you're interested
http://www.wescottdesign.com
On Saturday, May 14, 2016 at 12:02:39 AM UTC-7, Jasen Betts wrote:
On 2016-05-14, mrdarrett@gmail.com <mrdarrett@gmail.com> wrote:
On Friday, May 13, 2016 at 7:35:17 PM UTC-7, mrda...@gmail.com wrote:
I took apart an old inkjet printer and was surprised the stepper
motor has such resistance to it, if it's just an iron gear rotor.
What gives?
Never mind, I think I figured it out. It's got a permanent magnet
for a rotor. (?!)
yeah, they're steppers, not switched reluctance.
--
\_(ă)_
The search for a cheap reluctance motor continues.
<snip>
PM steppers actually do have variable reluctance magnetic paths -- that's
why they have favored positions when they're powered down.
Basically, when you have a magnetic path, the magnetic attraction is in
the direction that reduces the reluctance of the path and takes the most
energy out of the magnetic circuit. With a magnetic circuit "powered" by
a permanent magnet, this energy comes out of the magnet (and is returned
when you pull things apart). With a variable reluctance motor, this
energy comes out of motor's source of current.
If you just want to do a science experiment with reluctance motors, you
could make one by hand -- a soft iron bar or ferrite on a shaft and a
pair of coils should give you something that will spin if you treat it
right.
--
Tim Wescott
Control systems, embedded software and circuit design
I'm looking for work! See my website if you're interested
http://www.wescottdesign.com
J
Jasen Betts
Guest
On 2016-05-15, mrdarrett@gmail.com <mrdarrett@gmail.com> wrote:
every two steps the flux path through the rotor reverses (WRT rotor)
if it wasn't laminated there would be large eddy currents getting in
the way of the flux, and producing extra heat..
--
\_(ă)_
every two steps the flux path through the rotor reverses (WRT rotor)
if it wasn't laminated there would be large eddy currents getting in
the way of the flux, and producing extra heat..
--
\_(ă)_
D
default
Guest
On Sat, 14 May 2016 12:39:46 -0700, John Larkin
<jjlarkin@highlandtechnology.com> wrote:
There was an interesting application in "Nut's and Volts" years ago
where the author used one as a rotary encoder and to read out the
position on an up-down counter. One phase was input to the clock and
the other to the U/D pin.
I did that for a kind of selsyn. One stepper generates the signal to
turn the slave (driving a potentiometer in my application). I used
op-amps with protection diodes with their full open loop gain of ~200K
(with protection diodes to limit the voltage on the inputs). I
couldn't turn the input stepper so slow that it wouldn't make the
slave move...
No holding torque (but that's the way I wanted it). Add some flip
flops and I could have also had holding torque.
<jjlarkin@highlandtechnology.com> wrote:
There was an interesting application in "Nut's and Volts" years ago
where the author used one as a rotary encoder and to read out the
position on an up-down counter. One phase was input to the clock and
the other to the U/D pin.
I did that for a kind of selsyn. One stepper generates the signal to
turn the slave (driving a potentiometer in my application). I used
op-amps with protection diodes with their full open loop gain of ~200K
(with protection diodes to limit the voltage on the inputs). I
couldn't turn the input stepper so slow that it wouldn't make the
slave move...
No holding torque (but that's the way I wanted it). Add some flip
flops and I could have also had holding torque.
M
Michael Black
Guest
On Sat, 14 May 2016, John Larkin wrote:
and I got a white LED to light. I needed a bigger capacitor, but the
concept was there. I didn't find that stepper motor difficult to turn.
Yes, it was't like a cheap DC motor out of a toy, but it wasn't "hard" to
turn.
Michael
Yes, I took a random stepper motor and added some diodes and a capacitor,
and I got a white LED to light. I needed a bigger capacitor, but the
concept was there. I didn't find that stepper motor difficult to turn.
Yes, it was't like a cheap DC motor out of a toy, but it wasn't "hard" to
turn.
Michael