## Re: How to estimate basic parameters of retrived stepper motors?

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• ... than ... low ... A simple unipolar driver typically uses higher voltages, but large resistors that shed heat. the current limiting resistors can cost as
Message 1 of 25 , Sep 1, 2004
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> Also most often you will drive the motor with a much higher voltage
than
> nominal,
> and so the data doesn't matter much, as long as the resistance is
low
> enough to get
> some current through it.
>
> ST

A simple unipolar driver typically uses higher voltages, but large
resistors that shed heat. the current limiting resistors can cost as
much as a home-brew driver board.

Imagin a 2 ohm, 5 watt stepper. could be 7 volts and 3/4 amps.
could be 2 volts and 2.5 amps.

Most likly it is 3/4 to 1.5 amps.
that would mean you could safley put 48 volts thru the motor.
BUT, you must limit the motor to base current or 3/4 amps for safety
of testing. The resistor would have a very high watt rating.

Since the stepper was removed from a machine there would be driver
chips in the machine if not a complete driver board and power supply.

Probably the easiest way to get it running it to use the stuff it
came with.

Dave
• ... Not on the motor in steady-state (not chopped). It can only be 3.16V 1.58A, otherwise ohm s law wouldn t be correct. ... IMO that current limiting resistor
Message 2 of 25 , Sep 1, 2004
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> A simple unipolar driver typically uses higher voltages, but large
> resistors that shed heat. the current limiting resistors can cost as
> much as a home-brew driver board.
>
> Imagin a 2 ohm, 5 watt stepper. could be 7 volts and 3/4 amps.
> could be 2 volts and 2.5 amps.

Not on the motor in steady-state (not chopped).
It can only be 3.16V 1.58A, otherwise ohm's law wouldn't be correct.

>
> Most likly it is 3/4 to 1.5 amps.
> that would mean you could safley put 48 volts thru the motor.
> BUT, you must limit the motor to base current or 3/4 amps for safety
> of testing. The resistor would have a very high watt rating.
>
> Since the stepper was removed from a machine there would be driver
> chips in the machine if not a complete driver board and power supply.
>
> Probably the easiest way to get it running it to use the stuff it
> came with.
>
> Dave
>

IMO that current limiting resistor thing is nonsense (sorry).
What you WANT to do is QUICKLY increase the motor current to maximum,
perhaps
you would even like to overload it a bit to get high speeds.
The current rise rate is limited by the EMF of the motor (load and inertia)
and by the inductance and internal resistance. If you apply more voltage
you get a higher rate.

Now, please compare a drive with say 5V, and one with 10V designed to drop
half the voltage on a resistor. What do you get?
Simple: the 5V drive will rise to the intended current faster.

You only introduce resistance, that won't make it faster.
If you believe that is wrong, please tell me why and what happens.
I don't understand at all what sense it should make to use high voltage
and burn most
of it.

ST
• ... Thought about it, and i was wrong. Adding resistance DOES make it faster. During the transient the current is small, thus the drop over the resistance is
Message 3 of 25 , Sep 1, 2004
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>
> You only introduce resistance, that won't make it faster.
>
> ST
>

Thought about it, and i was wrong.
Adding resistance DOES make it faster.
During the transient the current is small, thus the drop over the
resistance
is low and the motor will "see" the higher voltage.
Even did a quick pspice simulation to see what's going on.

sorry for the cunfusion.
I still think it is not a good way to design a stepper driver, considering
the low added cost for a chopper.

ST
• ... considering ... I completely agree. But there are many people who want to run those tiny pressed can printer steppers and floppy disk steppers. Adding a
Message 4 of 25 , Sep 1, 2004
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--- In Electronics_101@yahoogroups.com, "Stefan Trethan"
<stefan_trethan@g...> wrote:
>
> >
> > You only introduce resistance, that won't make it faster.
> >
> > ST
> >
>
> Thought about it, and i was wrong.
> Adding resistance DOES make it faster.
> During the transient the current is small, thus the drop over the
> resistance
> is low and the motor will "see" the higher voltage.
> Even did a quick pspice simulation to see what's going on.
>
> sorry for the cunfusion.
> I still think it is not a good way to design a stepper driver,
considering
> the low added cost for a chopper.
>
> ST

I completely agree. But there are many people who want to run those
tiny pressed can printer steppers and floppy disk steppers. Adding a
2 watt resistor to make it move because that's what you have on hand
is convieninece.

The reasons for using resistive limiting are
ease of circuit design
parts on hand

the reasons against
expensive power resistors
high heat losses
poor performance

The resistive circuit will still slow the motor down as it cannot
deliver power as fast as a chopper driver.

But, for slow motion applications and with a short run like in a
printer that sits 99% of the time, it would be an acceptable design.

Dave
• ... Ok, try this: You energize a particular motor winding with that 10V, and a resistor, but initially there is _no_ current flowing because of the motor s
Message 5 of 25 , Sep 1, 2004
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On Wednesday 01 September 2004 05:41 am, Stefan Trethan wrote:

> IMO that current limiting resistor thing is nonsense (sorry). What you WANT
> to do is QUICKLY increase the motor current to maximum, perhaps
> you would even like to overload it a bit to get high speeds. The current
> rise rate is limited by the EMF of the motor (load and inertia) and by the
> inductance and internal resistance. If you apply more voltage you get a
> higher rate.
>
> Now, please compare a drive with say 5V, and one with 10V designed to drop
> half the voltage on a resistor. What do you get? Simple: the 5V drive will
> rise to the intended current faster.
>
> You only introduce resistance, that won't make it faster. If you believe
> that is wrong, please tell me why and what happens. I don't understand at
> all what sense it should make to use high voltage and burn most of it.

Ok, try this: You energize a particular motor winding with that 10V, and a
resistor, but initially there is _no_ current flowing because of the motor's
inductance, and therefore there is no voltage drop across the resistor. The
current has to ramp up the same way the voltage across a capacitor does. And
it'll do it faster in this case than it would with just the 5 volt supply and
no resistor because while the current is at a lower level the voltage is
higher.
• ... actually i have never seen a resistive one in a printer... have you? ST
Message 6 of 25 , Sep 1, 2004
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> But, for slow motion applications and with a short run like in a
> printer that sits 99% of the time, it would be an acceptable design.
>
> Dave
>

actually i have never seen a resistive one in a printer...
have you?

ST
• ... see my second message, i figured that out already. sorry ;-) ST
Message 7 of 25 , Sep 1, 2004
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> Ok, try this: You energize a particular motor winding with that 10V,
> and a
> resistor, but initially there is _no_ current flowing because of the
> motor's
> inductance, and therefore there is no voltage drop across the
> resistor. The
> current has to ramp up the same way the voltage across a capacitor
> does. And
> it'll do it faster in this case than it would with just the 5 volt
> supply and
> no resistor because while the current is at a lower level the voltage is
> higher.
>
>

see my second message, i figured that out already. sorry ;-)

ST
• ... Yeah, I did see that -- right after my post had gone out... :-)
Message 8 of 25 , Sep 1, 2004
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On Wednesday 01 September 2004 01:33 pm, Stefan Trethan wrote:
> > Ok, try this: You energize a particular motor winding with that 10V,
> > and a resistor, but initially there is _no_ current flowing because of
> > the motor's inductance, and therefore there is no voltage drop across the
> > resistor. The current has to ramp up the same way the voltage across a
> > capacitor does. And it'll do it faster in this case than it would with
> > just the 5 volt supply and no resistor because while the current is at a
> > lower level the voltage is higher.

> see my second message, i figured that out already. sorry ;-)

Yeah, I did see that -- right after my post had gone out... :-)
• Hello Big thanks for Dave, Stefan and Roy for your usefully suggestion. I have applied that to my motor and now that seems to be really simple. I think that is
Message 9 of 25 , Sep 3, 2004
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Hello

Big thanks for Dave, Stefan and Roy for your usefully suggestion.

I have applied that to my motor and now that seems to be really
simple. I think that is good idea to use used motors in our
application especially the cost of that is almost zero.
I have found in specialist books another pattern with help us to
calculate current in wires. It is in addiction /// Mat's first
enclouser/// (in file for group)
Moreover I noticed short discussion about types of controlling for
stepper motors. In second addition I enclosures part of my report
about stepper motors///Mat's second enclouser///. Maybe that
information will help somebody

The best regards
Mateusz
• ... I ve downloaded these and am having a bit of trouble opening the second one, what software did you use to make that?
Message 10 of 25 , Sep 4, 2004
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On Saturday 04 September 2004 02:23 am, Mateusz wrote:
> Hello
>
> Big thanks for Dave, Stefan and Roy for your usefully suggestion.
>
> I have applied that to my motor and now that seems to be really
> simple. I think that is good idea to use used motors in our
> application especially the cost of that is almost zero.
> I have found in specialist books another pattern with help us to
> calculate current in wires. It is in addiction /// Mat's first
> enclouser/// (in file for group)
> Moreover I noticed short discussion about types of controlling for
> stepper motors. In second addition I enclosures part of my report
> about stepper motors///Mat's second enclouser///. Maybe that
> information will help somebody

I've downloaded these and am having a bit of trouble opening the second one,
what software did you use to make that?
• Hello You shouldnt have any problem with open the secont encloser because it was maded in Microsoft WORD 2000. lets try open,everything is working properlly.
Message 11 of 25 , Sep 4, 2004
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Hello
You shouldnt have any problem with open the secont encloser because
it was maded in Microsoft WORD 2000.
lets try open,everything is working properlly.

cheer
Mateusz

> I've downloaded these and am having a bit of trouble opening the
second one,
> what software did you use to make that?
• ... Hmmm i can t find it anymore in the files, where is it gone? I didn t try to open it seeing it is a .DOC. Now i wanted to download it and convert to PDF
Message 12 of 25 , Sep 4, 2004
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On Sat, 04 Sep 2004 21:53:14 -0000, Mateusz <mat_eusz@...> wrote:

>
> Hello
> You shouldnt have any problem with open the secont encloser because
> it was maded in Microsoft WORD 2000.
> lets try open,everything is working properlly.
>
> cheer
> Mateusz
>
>
>
>
>> I've downloaded these and am having a bit of trouble opening the
> second one,
>> what software did you use to make that?
>
>
>

Hmmm i can't find it anymore in the files, where is it gone?
I didn't try to open it seeing it is a .DOC. Now i wanted to download
it and convert to PDF but it seems i can't find it.

ST
• ... download ... Look in the Stepper Drivers folder. I pdf d them and put them there. If I didn t mess up the file they should be readable. Dave
Message 13 of 25 , Sep 5, 2004
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>
> Hmmm i can't find it anymore in the files, where is it gone?
> I didn't try to open it seeing it is a .DOC. Now i wanted to
> it and convert to PDF but it seems i can't find it.
>
> ST

Look in the Stepper Drivers folder.

I pdf'd them and put them there. If I didn't mess up the file they

Dave
• Hello Stefan unfortunatelly i have no idea what is wrong because it work properlly. if you are stronglly interested in this short raport (but i am sure for you
Message 14 of 25 , Sep 5, 2004
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Hello Stefan
unfortunatelly i have no idea what is wrong because it work properlly. if you are stronglly interested in this short raport (but i am sure for you that is only simple explanation) than i will send do your e-mail that word-documend.
leave me message: sccot7@...
cheers
Mateusz

Stefan Trethan <stefan_trethan@...> wrote:

On Sat, 04 Sep 2004 21:53:14 -0000, Mateusz wrote:

>
> Hello
> You shouldnt have any problem with open the secont encloser because
> it was maded in Microsoft WORD 2000.
> lets try open,everything is working properlly.
>
> cheer
> Mateusz
>
>
>
>
>> I've downloaded these and am having a bit of trouble opening the
> second one,
>> what software did you use to make that?
>
>
>

Hmmm i can't find it anymore in the files, where is it gone?
I didn't try to open it seeing it is a .DOC. Now i wanted to download
it and convert to PDF but it seems i can't find it.

ST

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• On Sun, 5 Sep 2004 06:28:45 -0700 (PDT), Mateusz Goÿffffb3ÿffffb9bek ... Nah it s working fine now, Dave has converted it to PDF and put in the stepper
Message 15 of 25 , Sep 5, 2004
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On Sun, 5 Sep 2004 06:28:45 -0700 (PDT), Mateusz Goÿffffb3ÿffffb9bek
<mat_eusz@...> wrote:

> Hello Stefan
> unfortunatelly i have no idea what is wrong because it work properlly.
> if you are stronglly interested in this short raport (but i am sure for
> you that is only simple explanation) than i will send do your e-mail
> that word-documend.
> leave me message: sccot7@...
> cheers
> Mateusz
>

Nah it's working fine now, Dave has converted it to PDF and put in the
stepper driver folder.
PDF is much better for such stuff because almost everyone can open it no
version
problems etc..
By the way, thanks Dave.

ST
• Hello All: I am building a broad-band RF preselector using a schematic I got off the net, and it calls for a buffer amp that is an obsolete op amp. The
Message 16 of 25 , Sep 5, 2004
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Hello All:
I am building a broad-band RF preselector using a schematic I got off the net, and it calls for a buffer amp that is an obsolete op amp.  The preselector covers a range from about 300khz to 300mhz in twelve bands, and it has an MPF102 as a front end with an unusual round-can op-amp as a buffer following the front end.  The part is LH0033CG, which is described as a "fast buffer" in all the searches I have done.

Does anyone have recommendations for cheap, easily available op amps that would fit the bill for this project?  In my searches, I have not found any spec sheets for the LH0033CG, so I cannot help with cross reference information.

This is really frustrating, because the preselector is a really nice design and I am anxious to get started on the project in time for winter DX listening here in the northern hemisphere.

Any help would be most appreciated.
Thanks, Barry

• That specific part number is no longer in production. National Semiconductor made a version of it. However, if you search at http://www.digikey.com for LH0033
Message 17 of 25 , Sep 5, 2004
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That specific part number is no longer in production. National
Semiconductor made a version of it.

However, if you search at http://www.digikey.com for LH0033 (no CG
suffix) you will find similar devices presumably with different
packaging but I didn't check. That is one expensive OP AMP!

--- In Electronics_101@yahoogroups.com, Barry Savage <sofistic@s...>
wrote:
> Hello All:
> I am building a broad-band RF preselector using a schematic I got
off the net, and it calls for a buffer amp that is an obsolete op
amp. The preselector covers a range from about 300khz to 300mhz in
twelve bands, and it has an MPF102 as a front end with an unusual
round-can op-amp as a buffer following the front end. The part is
LH0033CG, which is described as a "fast buffer" in all the searches
I have done.
>
> Does anyone have recommendations for cheap, easily available op
amps that would fit the bill for this project? In my searches, I
have not found any spec sheets for the LH0033CG, so I cannot help
with cross reference information.
>
> This is really frustrating, because the preselector is a really
nice design and I am anxious to get started on the project in time
for winter DX listening here in the northern hemisphere.
>
> Any help would be most appreciated.
> Thanks, Barry
• Thanks for the lead.... but.... ... I looked up the part number, and YIKES you are right. Digikey lists the price at about USD\$40, and they don t have any in
Message 18 of 25 , Sep 5, 2004
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>That specific part number is no longer in production.  National
>Semiconductor made a version of it.
>
>However, if you search at http://www.digikey.com for LH0033 (no CG
>suffix) you will find similar devices presumably with different
>packaging but I didn't check.  That is one expensive OP AMP!
I looked up the part number, and YIKES you are right.  Digikey lists the price at about USD\$40, and they don't have any in stock anyway.  They also say that the status is that it was "obsoleted by manufacturer."

Since I don't know anything about the specs except the range that the author says the preselector will tune (300khz to 300mhz), I can only look for op amps (preferrably cheap) that have a high gain bandwidth.  Perhaps I could just use another jfet or a bipolar as the buffer.

But I just can't believe that there are not some standard opamps out there for wide band RF applications.
Anybody else have some ideas?
Thanks,
Barry
• ... From: Barry Savage To: Electronics_101@yahoogroups.com Sent: Sunday, September 05, 2004 6:39 PM Subject: Re: [Electronics_101] Re: Need advice: common RF
Message 19 of 25 , Sep 5, 2004
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----- Original Message -----
From: Barry Savage
To: Electronics_101@yahoogroups.com
Sent: Sunday, September 05, 2004 6:39 PM
Subject: Re: [Electronics_101] Re: Need advice: common RF op amps

>That specific part number is no longer in production. National
>Semiconductor made a version of it.
>
>However, if you search at http://www.digikey.com for LH0033 (no CG
>suffix) you will find similar devices presumably with different
>packaging but I didn't check. That is one expensive OP AMP!

I looked up the part number, and YIKES you are right. Digikey lists the
price at about USD\$40, and they don't have any in stock anyway. They also
say that the status is that it was "obsoleted by manufacturer."

Since I don't know anything about the specs except the range that the author
says the preselector will tune (300khz to 300mhz), I can only look for op
amps (preferrably cheap) that have a high gain bandwidth. Perhaps I could
just use another jfet or a bipolar as the buffer.

But I just can't believe that there are not some standard opamps out there
for wide band RF applications.
Anybody else have some ideas?

They are very specialised, and hence expensive. Try Nat Semi and Elantec.
There are better pre-amp designs around that use modern parts.

Leon

Leon
• I thought there was a datasheet over at National Semi for one of the alternate packages. From there you can look through their offerings - some site have a
Message 20 of 25 , Sep 5, 2004
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I thought there was a datasheet over at National Semi for one of the
alternate packages. From there you can look through their offerings -
some site have a search by parameters.

--- In Electronics_101@yahoogroups.com, "Leon Heller"
<leon.heller@d...> wrote:
> ----- Original Message -----
> From: Barry Savage
> To: Electronics_101@yahoogroups.com
> Sent: Sunday, September 05, 2004 6:39 PM
> Subject: Re: [Electronics_101] Re: Need advice: common RF op amps
>
>
> Thanks for the lead.... but....
>
> >That specific part number is no longer in production. National
> >Semiconductor made a version of it.
> >
> >However, if you search at http://www.digikey.com for LH0033 (no CG
> >suffix) you will find similar devices presumably with different
> >packaging but I didn't check. That is one expensive OP AMP!
>
> I looked up the part number, and YIKES you are right. Digikey
lists the
> price at about USD\$40, and they don't have any in stock anyway.
They also
> say that the status is that it was "obsoleted by manufacturer."
>
> Since I don't know anything about the specs except the range that
the author
> says the preselector will tune (300khz to 300mhz), I can only look
for op
> amps (preferrably cheap) that have a high gain bandwidth. Perhaps
I could
> just use another jfet or a bipolar as the buffer.
>
> But I just can't believe that there are not some standard opamps
out there
> for wide band RF applications.
> Anybody else have some ideas?
>
> They are very specialised, and hence expensive. Try Nat Semi and
Elantec.
> There are better pre-amp designs around that use modern parts.
>
> Leon
>
> Leon
• In a message dated 9/5/2004 9:54:57 AM Central Standard Time, sofistic@sbcglobal.net writes: The part is LH0033CG, Barry: Isn t that a National Semiconductor
Message 21 of 25 , Sep 5, 2004
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In a message dated 9/5/2004 9:54:57 AM Central Standard Time, sofistic@... writes:
The part is LH0033CG,
Barry:  Isn't that a National Semiconductor part-number:  Google?  Look if National has a cross-ref. sheet on-line, etc.
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