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

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  • Dave Mucha
    ... 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
    • Stefan Trethan
      ... 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
      • Stefan Trethan
        ... 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
        • Dave Mucha
          ... 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
          • Roy J. Tellason
            ... 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.
            • Stefan Trethan
              ... 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
              • Stefan Trethan
                ... 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
                • Roy J. Tellason
                  ... 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... :-)
                  • Mateusz
                    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
                    • Roy J. Tellason
                      ... 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?
                      • Mateusz
                        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?
                        • Stefan Trethan
                          ... 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
                          • Dave Mucha
                            ... 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
                              download
                              > 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
                              should be readable.

                              Dave
                            • MateuszGo�ffffb3�ffffb9bek
                              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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                              • Stefan Trethan
                                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
                                • Barry Savage
                                  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
                                     
                                  • rtstofer
                                    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
                                    • Barry Savage
                                      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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                                        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?
                                        Thanks,
                                        Barry
                                      • Leon Heller
                                        ... 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


                                          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
                                        • rtstofer
                                          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
                                          • JanRwl@AOL.COM
                                            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.
                                            Your message has been successfully submitted and would be delivered to recipients shortly.