Running Two Stepper Motors (3rd try)
Archiver
Posts: 46,084
Hi Ian,
(seems re-joining the group did the trick for me)
I tried posting this last night, but for some reason it didn't get
posted. I had a typo. (had to do with serial current and
parallel `current' not parallel `voltage')
A bit about steppers ; The industry puts a nameplate voltage on the
motors for calculations only. [noparse][[/noparse]except for Pacific Scientific] you
can verify your BASE DATA with ohms law and the resistance and
voltage or current. PacSci will be way off as they rate at
recommended voltage not lab calculation voltage. Has to do with
charging the motor.
Run them at a MINIMUM of 5 times nameplate voltage. At about 25
times nameplate voltage, the coils become saturated and there is no
additional benefit.
more voltage = more speed. 5 to 20 times nameplate is the range
where they actually perform well. Check the manufactures site, they
will use either 24 volts or 48 volts typically when showing
performance of their 5 volt motors.
Current is limited to nameplate for unipolar, but the power drain on
unipolar power supplies makes large motors expensive to run in
unipolar mode. Unipolar is fine for hobby work or applications where
power is not important. you will find dozens of very low power
unipolar drives and few for higher power units. Inversely, you will
mostly find chopper drives for high power units. Chopper perform so
much better it is not worth the effort to try to design a new uni-
polar drive.
Unipolar has an advantage when it comes to reversing speed. That is
from the nature of the V/L (voltage/inductance) relationship.
Unipolar drives charge one coil to spin one way, and another coil to
spin opposite. Bi-polar need to drain the coil first before they can
charge it to spin in the opposite direction. Typically reversing
speed is not critical.
If you use a chopper drive and wire the coils in series, you cut the
current in half. Wire them in parallel and you use nameplate
current. You can think of the motor nameplate as it's parallel rated
current. If you wire in series, you double the resistance, but
increase inductance by 4. Let me know if you want more data on this,
this post is long already and I don't want to add math to it.
Wiring the coils in series reduces top speed, but the motors run
cooler. At peak performance your hand would feel very uncomfortable
on a running stepper in parallel. they run HOT.
Most chopper drives in a reasonable price (less than $125.00) peak
out at about 70 volts so your 3 volt motors are perfect for a 25x
rating. This voltage is the highly sought voltage for the CNC-
machine tool crowd. Many steppers you see on e-bay are 5 volts or
over and are poor candidates. Higher voltage means very poor
performance.
If you have access to the unit you are looking into, check the power
supply voltage, and remember that on power supplies of this sort,
multiply the rectified DC by 1.414 to get the full DC voltage they
are using. Huge caps on the power supply are needed and they yield
near peak AC voltage, not RMS that you may be expecting or used to.
Math on request.
Choppers will also bring your coils up to full amps quickly and will
not use the full rated amps of the motor from the power supply. If
you have a 3 amp motor run from a chopper driver, expect to size the
power supply to 2 amps. Steppers are NOT like standard motors.
Again, math if you want it.
Another thing to be concerned about is back emf from the collapsing
coil, if you try to size your driver at peak voltage, the back emf
can increase the voltage over the power supply voltage by 5-10%. if
your driver chips are rated for 35 volts, design for 30 volts to be
on the safe side.
sounds like the unit you are looking into is engineered as a decent
piece of equipment, do you have a link to what you are trying to
duplicate ?
Dave
--- In basicstamps@yahoogroups.com, "Ian Phillips" <iphillips@s...>
wrote:
> I have looked at these but the amperage is to low. The stepper in
the
> demo unit is rated at 3.1 amp, 2.9vdc. I'm also not sure what kind
of a
> signal you would send to the driver.
>
>
Original Message
> From: Dennis P. O'Leary [noparse][[/noparse]mailto:doleary@e...]
> Sent: January 15, 2003 3:34 PM
> To: basicstamps@yahoogroups.com
> Subject: RE: [noparse][[/noparse]basicstamps] Running Two Stepper Motors
>
> Ian -
>
> Check out the motor controller and driver chips from SGS-Thomson,
> particularly the L297 and L298 combination.
>
> Dennis
>
>
Original Message
> From: iphillipsca <iphillips@s...>
> [noparse][[/noparse]mailto:iphillips@s...]
> Sent: Wednesday, January 15, 2003 6:32 AM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Running Two Stepper Motors
>
>
> I am building a large (4'x 7') scroller similar to those display
> signs you see around. I have a demo unit that is using two large
> steppers and being controlled by a PIC to motor driver and then
> MOSFETs. They want $3000 for this unit and needless to say I think
> that I could build it much cheaper. Questions- to run two steppers
> and look for switches( initiate, limits, and possibly speed
control)
> could the 2sx do this quickly enough? To drive the higher load of
the
> larger than average steppers, I was planning to use a PAK 5(AWC are
> you out there?) to a MOSFET. Is this the best device for this? Any
> opinions, ideas appreciated. Ian
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the
Subject
> and Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
>
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the
Subject
> and Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
(seems re-joining the group did the trick for me)
I tried posting this last night, but for some reason it didn't get
posted. I had a typo. (had to do with serial current and
parallel `current' not parallel `voltage')
A bit about steppers ; The industry puts a nameplate voltage on the
motors for calculations only. [noparse][[/noparse]except for Pacific Scientific] you
can verify your BASE DATA with ohms law and the resistance and
voltage or current. PacSci will be way off as they rate at
recommended voltage not lab calculation voltage. Has to do with
charging the motor.
Run them at a MINIMUM of 5 times nameplate voltage. At about 25
times nameplate voltage, the coils become saturated and there is no
additional benefit.
more voltage = more speed. 5 to 20 times nameplate is the range
where they actually perform well. Check the manufactures site, they
will use either 24 volts or 48 volts typically when showing
performance of their 5 volt motors.
Current is limited to nameplate for unipolar, but the power drain on
unipolar power supplies makes large motors expensive to run in
unipolar mode. Unipolar is fine for hobby work or applications where
power is not important. you will find dozens of very low power
unipolar drives and few for higher power units. Inversely, you will
mostly find chopper drives for high power units. Chopper perform so
much better it is not worth the effort to try to design a new uni-
polar drive.
Unipolar has an advantage when it comes to reversing speed. That is
from the nature of the V/L (voltage/inductance) relationship.
Unipolar drives charge one coil to spin one way, and another coil to
spin opposite. Bi-polar need to drain the coil first before they can
charge it to spin in the opposite direction. Typically reversing
speed is not critical.
If you use a chopper drive and wire the coils in series, you cut the
current in half. Wire them in parallel and you use nameplate
current. You can think of the motor nameplate as it's parallel rated
current. If you wire in series, you double the resistance, but
increase inductance by 4. Let me know if you want more data on this,
this post is long already and I don't want to add math to it.
Wiring the coils in series reduces top speed, but the motors run
cooler. At peak performance your hand would feel very uncomfortable
on a running stepper in parallel. they run HOT.
Most chopper drives in a reasonable price (less than $125.00) peak
out at about 70 volts so your 3 volt motors are perfect for a 25x
rating. This voltage is the highly sought voltage for the CNC-
machine tool crowd. Many steppers you see on e-bay are 5 volts or
over and are poor candidates. Higher voltage means very poor
performance.
If you have access to the unit you are looking into, check the power
supply voltage, and remember that on power supplies of this sort,
multiply the rectified DC by 1.414 to get the full DC voltage they
are using. Huge caps on the power supply are needed and they yield
near peak AC voltage, not RMS that you may be expecting or used to.
Math on request.
Choppers will also bring your coils up to full amps quickly and will
not use the full rated amps of the motor from the power supply. If
you have a 3 amp motor run from a chopper driver, expect to size the
power supply to 2 amps. Steppers are NOT like standard motors.
Again, math if you want it.
Another thing to be concerned about is back emf from the collapsing
coil, if you try to size your driver at peak voltage, the back emf
can increase the voltage over the power supply voltage by 5-10%. if
your driver chips are rated for 35 volts, design for 30 volts to be
on the safe side.
sounds like the unit you are looking into is engineered as a decent
piece of equipment, do you have a link to what you are trying to
duplicate ?
Dave
--- In basicstamps@yahoogroups.com, "Ian Phillips" <iphillips@s...>
wrote:
> I have looked at these but the amperage is to low. The stepper in
the
> demo unit is rated at 3.1 amp, 2.9vdc. I'm also not sure what kind
of a
> signal you would send to the driver.
>
>
Original Message
> From: Dennis P. O'Leary [noparse][[/noparse]mailto:doleary@e...]
> Sent: January 15, 2003 3:34 PM
> To: basicstamps@yahoogroups.com
> Subject: RE: [noparse][[/noparse]basicstamps] Running Two Stepper Motors
>
> Ian -
>
> Check out the motor controller and driver chips from SGS-Thomson,
> particularly the L297 and L298 combination.
>
> Dennis
>
>
Original Message
> From: iphillipsca <iphillips@s...>
> [noparse][[/noparse]mailto:iphillips@s...]
> Sent: Wednesday, January 15, 2003 6:32 AM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Running Two Stepper Motors
>
>
> I am building a large (4'x 7') scroller similar to those display
> signs you see around. I have a demo unit that is using two large
> steppers and being controlled by a PIC to motor driver and then
> MOSFETs. They want $3000 for this unit and needless to say I think
> that I could build it much cheaper. Questions- to run two steppers
> and look for switches( initiate, limits, and possibly speed
control)
> could the 2sx do this quickly enough? To drive the higher load of
the
> larger than average steppers, I was planning to use a PAK 5(AWC are
> you out there?) to a MOSFET. Is this the best device for this? Any
> opinions, ideas appreciated. Ian
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the
Subject
> and Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
>
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the
Subject
> and Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
Comments
rather tell you off group(copyrights and all that, don't want to get in
trouble). The motors are from Tamagawa code TS3134N9. I couldn't find
the exact match but found some close matches. The demo unit does have
very large caps and at least 10 MOSFETS and 4 transistors in what must
be the final output stage. I got a large amount of motor info from
Thomson/Aipax. Too much almost. It'll take me a while to get through it
all. I still have to find a similar motor. Digikey has a couple of large
Thomson units that might do it but they are 5 and 12 volt at 7.5 degree
with only 48 steps. If you know of a good source for large steppers I
would appreciate it. Ian
Original Message
From: david_mucha <david_mucha@y...> [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=Ku0TP-XKbtvNtcNvTl3Rg83cLomnesZtEjT25_lqHWuieMQH_9eE46BoiaSAjxJ2xcY5j4Se1OOTaHQ074HaLw]david_mucha@y...[/url
Sent: January 16, 2003 8:12 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Re: Running Two Stepper Motors (3rd try)
Hi Ian,
(seems re-joining the group did the trick for me)
I tried posting this last night, but for some reason it didn't get
posted. I had a typo. (had to do with serial current and
parallel `current' not parallel `voltage')
A bit about steppers ; The industry puts a nameplate voltage on the
motors for calculations only. [noparse][[/noparse]except for Pacific Scientific] you
can verify your BASE DATA with ohms law and the resistance and
voltage or current. PacSci will be way off as they rate at
recommended voltage not lab calculation voltage. Has to do with
charging the motor.
Run them at a MINIMUM of 5 times nameplate voltage. At about 25
times nameplate voltage, the coils become saturated and there is no
additional benefit.
more voltage = more speed. 5 to 20 times nameplate is the range
where they actually perform well. Check the manufactures site, they
will use either 24 volts or 48 volts typically when showing
performance of their 5 volt motors.
Current is limited to nameplate for unipolar, but the power drain on
unipolar power supplies makes large motors expensive to run in
unipolar mode. Unipolar is fine for hobby work or applications where
power is not important. you will find dozens of very low power
unipolar drives and few for higher power units. Inversely, you will
mostly find chopper drives for high power units. Chopper perform so
much better it is not worth the effort to try to design a new uni-
polar drive.
Unipolar has an advantage when it comes to reversing speed. That is
from the nature of the V/L (voltage/inductance) relationship.
Unipolar drives charge one coil to spin one way, and another coil to
spin opposite. Bi-polar need to drain the coil first before they can
charge it to spin in the opposite direction. Typically reversing
speed is not critical.
If you use a chopper drive and wire the coils in series, you cut the
current in half. Wire them in parallel and you use nameplate
current. You can think of the motor nameplate as it's parallel rated
current. If you wire in series, you double the resistance, but
increase inductance by 4. Let me know if you want more data on this,
this post is long already and I don't want to add math to it.
Wiring the coils in series reduces top speed, but the motors run
cooler. At peak performance your hand would feel very uncomfortable
on a running stepper in parallel. they run HOT.
Most chopper drives in a reasonable price (less than $125.00) peak
out at about 70 volts so your 3 volt motors are perfect for a 25x
rating. This voltage is the highly sought voltage for the CNC-
machine tool crowd. Many steppers you see on e-bay are 5 volts or
over and are poor candidates. Higher voltage means very poor
performance.
If you have access to the unit you are looking into, check the power
supply voltage, and remember that on power supplies of this sort,
multiply the rectified DC by 1.414 to get the full DC voltage they
are using. Huge caps on the power supply are needed and they yield
near peak AC voltage, not RMS that you may be expecting or used to.
Math on request.
Choppers will also bring your coils up to full amps quickly and will
not use the full rated amps of the motor from the power supply. If
you have a 3 amp motor run from a chopper driver, expect to size the
power supply to 2 amps. Steppers are NOT like standard motors.
Again, math if you want it.
Another thing to be concerned about is back emf from the collapsing
coil, if you try to size your driver at peak voltage, the back emf
can increase the voltage over the power supply voltage by 5-10%. if
your driver chips are rated for 35 volts, design for 30 volts to be
on the safe side.
sounds like the unit you are looking into is engineered as a decent
piece of equipment, do you have a link to what you are trying to
duplicate ?
Dave
Dover, NH. You might want to look at
Part Number LB42BLK-5 or something similar. Be aware that they are
expensive.
Jim
Original Message
From: Ian Phillips [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=JJzUvyEctgV64V6H8k_u6tif6f16WL21nUUcqJ7Bg6F_Caw8HBL0Yi0DV5rc4eimsvqr5I3nuIGdJXzxFtE]iphillips@s...[/url
Sent: Thursday, January 16, 2003 8:53 AM
To: basicstamps@yahoogroups.com
Subject: RE: [noparse][[/noparse]basicstamps] Re: Running Two Stepper Motors (3rd try)
Thanks Dave for all the info. If you would like to know the make I'd
rather tell you off group(copyrights and all that, don't want to get in
trouble). The motors are from Tamagawa code TS3134N9. I couldn't find
the exact match but found some close matches. The demo unit does have
very large caps and at least 10 MOSFETS and 4 transistors in what must
be the final output stage. I got a large amount of motor info from
Thomson/Aipax. Too much almost. It'll take me a while to get through it
all. I still have to find a similar motor. Digikey has a couple of large
Thomson units that might do it but they are 5 and 12 volt at 7.5 degree
with only 48 steps. If you know of a good source for large steppers I
would appreciate it. Ian
Original Message
From: david_mucha <david_mucha@y...> [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=KfDK3AKpPo6NQ3-dNfIHOe0kzCClHSoX9RevNGTGxyw91VEKev3RqLu1FTnz-W03toFd77iAGaUuMrHQ]david_mucha@y...[/url
Sent: January 16, 2003 8:12 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Re: Running Two Stepper Motors (3rd try)
Hi Ian,
(seems re-joining the group did the trick for me)
I tried posting this last night, but for some reason it didn't get
posted. I had a typo. (had to do with serial current and
parallel `current' not parallel `voltage')
A bit about steppers ; The industry puts a nameplate voltage on the
motors for calculations only. [noparse][[/noparse]except for Pacific Scientific] you
can verify your BASE DATA with ohms law and the resistance and
voltage or current. PacSci will be way off as they rate at
recommended voltage not lab calculation voltage. Has to do with
charging the motor.
Run them at a MINIMUM of 5 times nameplate voltage. At about 25
times nameplate voltage, the coils become saturated and there is no
additional benefit.
more voltage = more speed. 5 to 20 times nameplate is the range
where they actually perform well. Check the manufactures site, they
will use either 24 volts or 48 volts typically when showing
performance of their 5 volt motors.
Current is limited to nameplate for unipolar, but the power drain on
unipolar power supplies makes large motors expensive to run in
unipolar mode. Unipolar is fine for hobby work or applications where
power is not important. you will find dozens of very low power
unipolar drives and few for higher power units. Inversely, you will
mostly find chopper drives for high power units. Chopper perform so
much better it is not worth the effort to try to design a new uni-
polar drive.
Unipolar has an advantage when it comes to reversing speed. That is
from the nature of the V/L (voltage/inductance) relationship.
Unipolar drives charge one coil to spin one way, and another coil to
spin opposite. Bi-polar need to drain the coil first before they can
charge it to spin in the opposite direction. Typically reversing
speed is not critical.
If you use a chopper drive and wire the coils in series, you cut the
current in half. Wire them in parallel and you use nameplate
current. You can think of the motor nameplate as it's parallel rated
current. If you wire in series, you double the resistance, but
increase inductance by 4. Let me know if you want more data on this,
this post is long already and I don't want to add math to it.
Wiring the coils in series reduces top speed, but the motors run
cooler. At peak performance your hand would feel very uncomfortable
on a running stepper in parallel. they run HOT.
Most chopper drives in a reasonable price (less than $125.00) peak
out at about 70 volts so your 3 volt motors are perfect for a 25x
rating. This voltage is the highly sought voltage for the CNC-
machine tool crowd. Many steppers you see on e-bay are 5 volts or
over and are poor candidates. Higher voltage means very poor
performance.
If you have access to the unit you are looking into, check the power
supply voltage, and remember that on power supplies of this sort,
multiply the rectified DC by 1.414 to get the full DC voltage they
are using. Huge caps on the power supply are needed and they yield
near peak AC voltage, not RMS that you may be expecting or used to.
Math on request.
Choppers will also bring your coils up to full amps quickly and will
not use the full rated amps of the motor from the power supply. If
you have a 3 amp motor run from a chopper driver, expect to size the
power supply to 2 amps. Steppers are NOT like standard motors.
Again, math if you want it.
Another thing to be concerned about is back emf from the collapsing
coil, if you try to size your driver at peak voltage, the back emf
can increase the voltage over the power supply voltage by 5-10%. if
your driver chips are rated for 35 volts, design for 30 volts to be
on the safe side.
sounds like the unit you are looking into is engineered as a decent
piece of equipment, do you have a link to what you are trying to
duplicate ?
Dave
To UNSUBSCRIBE, just send mail to:
basicstamps-unsubscribe@yahoogroups.com
from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
[noparse][[/noparse]Non-text portions of this message have been removed]
I'm not sure what side of the pond you are on. if you are in the
states, then Jameco has a wide (can cheap) selection of small
steppers for hobby use.
Once you move out of the hobby range, you enter the world of
standards. NEMA lists motors as 17, 23, 34, 42 and so on. There is
a limit to the size of a stepper so you will never see a NEMA86 or
some such. each increase n size brings a limit to speed, so it is
rare to find more than a NEMA34. has to do with time constants and
coil charging.
The unit you have is a model TS31 in a NEMA34 size (3.4 inches in
diameter or 3.4" x3.4" if square. the rating from their site shows a
powerful motor, at over 550 oz/in (4 newton meter)
Sanyo Denki in the States makes nice motor, but new, these are pricey.
To get a similar motor, look for NEMA34 and between 550oz/in to
700oz/in or 4 to 4.5 newton meter torque.
http://www.mendonet.com/steppers/nema34.htm
regardng caps, yes, large caps. figure cap size is related to
voltage and current.
equation of (C= (80,000 * I) / V))
C is the value in microfarads,
I is the current and V is the voltage.
assuming a low voltage power supply of 30 volts, and 3 amps, you
would use 8,000uF for each motor, and get caps rated for at least 25%
greater than your peak voltage.
I have some lines on lower power units, NEMA34, 1.7 volt, 4.7 amps,
at $50.00 they are much less than new units, and I think one third
the power. yours are triple stack, or really 3 sets of coils for a
long motor.
and please e-mail me a link to the pic.
Dave
--- In basicstamps@yahoogroups.com, "Ian Phillips" <iphillips@s...>
wrote:
>
>
> Thanks Dave for all the info. If you would like to know the make I'd
> rather tell you off group(copyrights and all that, don't want to
get in
> trouble). The motors are from Tamagawa code TS3134N9. I couldn't
find
> the exact match but found some close matches. The demo unit does
have
> very large caps and at least 10 MOSFETS and 4 transistors in what
must
> be the final output stage. I got a large amount of motor info from
> Thomson/Aipax. Too much almost. It'll take me a while to get
through it
> all. I still have to find a similar motor. Digikey has a couple of
large
> Thomson units that might do it but they are 5 and 12 volt at 7.5
degree
> with only 48 steps. If you know of a good source for large steppers
I
> would appreciate it. Ian
>
Original Message
> From: david_mucha <david_mucha@y...> [noparse][[/noparse]mailto:david_mucha@y...]
>
> Sent: January 16, 2003 8:12 AM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Re: Running Two Stepper Motors (3rd try)
>
> Hi Ian,
>
> (seems re-joining the group did the trick for me)
>
> I tried posting this last night, but for some reason it didn't get
> posted. I had a typo. (had to do with serial current and
> parallel `current' not parallel `voltage')
>
> A bit about steppers ; The industry puts a nameplate voltage on the
> motors for calculations only. [noparse][[/noparse]except for Pacific Scientific] you
> can verify your BASE DATA with ohms law and the resistance and
> voltage or current. PacSci will be way off as they rate at
> recommended voltage not lab calculation voltage. Has to do with
> charging the motor.
>
> Run them at a MINIMUM of 5 times nameplate voltage. At about 25
> times nameplate voltage, the coils become saturated and there is no
> additional benefit.
>
> more voltage = more speed. 5 to 20 times nameplate is the range
> where they actually perform well. Check the manufactures site,
they
> will use either 24 volts or 48 volts typically when showing
> performance of their 5 volt motors.
>
> Current is limited to nameplate for unipolar, but the power drain
on
> unipolar power supplies makes large motors expensive to run in
> unipolar mode. Unipolar is fine for hobby work or applications
where
> power is not important. you will find dozens of very low power
> unipolar drives and few for higher power units. Inversely, you
will
> mostly find chopper drives for high power units. Chopper perform
so
> much better it is not worth the effort to try to design a new uni-
> polar drive.
>
> Unipolar has an advantage when it comes to reversing speed. That is
> from the nature of the V/L (voltage/inductance) relationship.
> Unipolar drives charge one coil to spin one way, and another coil
to
> spin opposite. Bi-polar need to drain the coil first before they
can
> charge it to spin in the opposite direction. Typically reversing
> speed is not critical.
>
> If you use a chopper drive and wire the coils in series, you cut
the
> current in half. Wire them in parallel and you use nameplate
> current. You can think of the motor nameplate as it's parallel
rated
> current. If you wire in series, you double the resistance, but
> increase inductance by 4. Let me know if you want more data on
this,
> this post is long already and I don't want to add math to it.
>
> Wiring the coils in series reduces top speed, but the motors run
> cooler. At peak performance your hand would feel very
uncomfortable
> on a running stepper in parallel. they run HOT.
>
> Most chopper drives in a reasonable price (less than $125.00) peak
> out at about 70 volts so your 3 volt motors are perfect for a 25x
> rating. This voltage is the highly sought voltage for the CNC-
> machine tool crowd. Many steppers you see on e-bay are 5 volts or
> over and are poor candidates. Higher voltage means very poor
> performance.
>
> If you have access to the unit you are looking into, check the
power
> supply voltage, and remember that on power supplies of this sort,
> multiply the rectified DC by 1.414 to get the full DC voltage they
> are using. Huge caps on the power supply are needed and they yield
> near peak AC voltage, not RMS that you may be expecting or used
to.
> Math on request.
>
> Choppers will also bring your coils up to full amps quickly and
will
> not use the full rated amps of the motor from the power supply. If
> you have a 3 amp motor run from a chopper driver, expect to size
the
> power supply to 2 amps. Steppers are NOT like standard motors.
> Again, math if you want it.
>
> Another thing to be concerned about is back emf from the collapsing
> coil, if you try to size your driver at peak voltage, the back emf
> can increase the voltage over the power supply voltage by 5-10%.
if
> your driver chips are rated for 35 volts, design for 30 volts to be
> on the safe side.
>
> sounds like the unit you are looking into is engineered as a decent
> piece of equipment, do you have a link to what you are trying to
> duplicate ?
>
> Dave