stepper motor transistors

Discussion in 'General Electronics Chat' started by JK-FlipFlop, Jul 5, 2010.

  1. JK-FlipFlop

    Thread Starter Member

    Jul 5, 2010
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    Which transistor I need to driver a common stepper motor?

    This one is ok??
    IRF520

    Thanks.
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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    That device is a power FET, not a transistor. It is probably going to work, but be aware (get the data sheet) that FET's are quite different from transistors in how they are controlled.

    Give us some more data on the stepper motor, and the circuit you were planning to use to do the driving.
     
  3. SgtWookie

    Expert

    Jul 17, 2007
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    The IRF520 N-channel standard power MOSFET has been around for a number of years now. It's still used, but is somewhat "long in the tooth".

    You need to better define your requirements.

    How do you plan on controlling the transistors/MOSFETs? If you are using a uC or 5v logic, you really need to use logic-level MOSFETs which turn fully ON at 5v. For International Rectifier (IR) and Vishay MOSFETs, these logic level parts start with "IRL" instead of "IRF"

    What is the manufacturer and part number of the stepper motor? Do you have the datasheet for it?
    What is the voltage and current rating of the stepper motor?
    Is it a unipolar, bipolar, or universal type stepper motor?
    The datasheet will answer the above questions.

    If you don't have/can't find a datasheet, here are some general hints:
    Bipolar stepper motors are the most difficult type for a hobbyist to use. They have four wires; internally there are two coils, and the ends of the coils are connected to the wires. Each wire has to be connected to an H-bridge, so that the direction of current flow through the coils can be reversed.

    Unipolar stepper motors are the easiest to drive; they have five or six wires. The motors have two center-tapped coils. You connect the center tap to +V, and alternately ground the ends of the coils using transistors or MOSFETs. These steppers can also be used as bipolar steppers if the center winding is not used.

    Universal stepper motors have eight wires. These have the most options, as they can be used as unipolar steppers, or as bipolar steppers with the coils connected in series or parallel. However, figuring out what is what can be complex, confusing and frustrating for a newcomer. Having a datasheet for these type motors will be an enormous help.
     
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  4. JK-FlipFlop

    Thread Starter Member

    Jul 5, 2010
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    Thank you for your comments.

    I have a stepper motor from a printer,
    and I want to control this motor by my uC (PIC18F4520).
    The stepper has 4 inputs, and I need to driver the outport for the motor inputs.
    so if you have a good experience in stepper motors, which transistor is the best for this purpose??

    Thanks.
     
  5. SgtWookie

    Expert

    Jul 17, 2007
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    Do you still have the printer? The necessary components to drive the stepper motor will be on the printed circuit boards in the printer. You need to find out where they are.

    You did not say what manufacturer made the stepper, or what part number is on it.

    It sounds like it is a bipolar stepper motor. It could also be a 3-phase or BLDC motor. You need to determine which type it is.

    [eta]
    With a bipolar motor, you will have two pairs of wires that are isolated from each other.

    With a BLDC motor, they will all seem to be connected together. However, if you use an accurate meter set to the lowest Ohms scale, you should find that one of the wires has 1/2 the resistance to all of the other wires. That is because the motor has three coils. One end of all three coils are connected together as a common supply wire. The other ends of the coils have individual wires. It is basically a wye winding.

    Link to an image: http://www.claytonengineering.com/training/myweb6/Module04/Output/images/t-f21.gif

    [​IMG]
     
    Last edited: Jul 5, 2010
  6. SgtWookie

    Expert

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    I added to my post as you were posting.

    You need to figure out what kind of motor you are working with.

    Without a manufacturer and part number, you'll have to figure it out using a multimeter set to read low Ohms.

    Meanwhile, here is a reasonably inexpensive N-ch logic level MOSFET that has a low gate charge and high current which you can drive directly from your uC:
    http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=IRLU2703PBF-ND

    You will need other parts along with it, such as fast recovery diodes and other things. However, we don't know anything about the motor besides it having four wires.

    You need to figure out if all four wires are connected, or if you have two pairs.

    A 3-phase/BLDC motor will be easier to drive than a bipolar stepper motor.

    If you have a bipolar stepper motor, you would be better off buying a complete bipolar stepper motor driver, something like this:
    http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=TB6560AHQO-ND
     
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  7. JK-FlipFlop

    Thread Starter Member

    Jul 5, 2010
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    I don't have the printer board and nor the motor name (except one of them), so I must control it with my uC without knowing the specifications.

    I need it for my CNC project, I have already two road of printers, I just need to control the motors precisely...

    thank you for your info.
     
  8. SgtWookie

    Expert

    Jul 17, 2007
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    Well, if you remember the printer make and model, you might try to track down a service manual for it. That will at least give the part numbers for the motor, and diagram to how it was wired up in the printer. It will also give you clues as to what the supply voltage and currents were, and perhaps even the motor controller circuitry.

    The risk you're running without having that info on hand is spending money on the project, then burning up the motor. It will be a learning process. Hopefully you don't destroy anything while learning.

    See if you can find the printer service manual.

    But before that, try using a meter on the motor wires.

    Arbitrarily label them "1", "2", "3" and "4" using some masking tape and a marker.

    Then measure the resistance from 1 to 2, then 1 to 3, then 1 to 4. Write them down.

    Then measure from 2 to 3, and 2 to 4. Write them down.

    Then measure from 3 to 4. Write it down.

    You will then have all possible connections covered. Respond with your measurements.

    Make sure to short the meter leads together, and report the resistance that you read for that as well.
     
  9. SgtWookie

    Expert

    Jul 17, 2007
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    Quote this, and fill in the readings in Ohms that you get (if no connection, write "NC") using at least 3 digits; ex: 1.23 or NC

    Shorting meter probes together measures (Ohms):
    (If greater than 2.00 Ohms, you have bad meter probes or your meter needs cleaning/adjustment)

    1 to 2 measures (Ohms/NC):

    1 to 3 measures (Ohms/NC):

    1 to 4 measures (Ohms/NC):

    2 to 3 measures (Ohms/NC):

    2 to 4 measures (Ohms/NC):

    3 to 4 measures (Ohms/NC):
     
    Last edited: Jul 5, 2010
  10. JK-FlipFlop

    Thread Starter Member

    Jul 5, 2010
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  11. SgtWookie

    Expert

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    If you have a 3-phase/BLDC motor, you won't be able to use L297/L298 pairs.

    The L298 is really "long in the tooth" (old technology). 2A max constant current, and at that rate you're dropping 4V across the H-bridge itself. Since it's a dual H-Bridge, that means 8v*2A = 16 Watts, which is a lot of heat to get rid of.
     
    Last edited: Jul 5, 2010
  12. JK-FlipFlop

    Thread Starter Member

    Jul 5, 2010
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    the name of the motor is Mitsumi M42SP-7 (7ohms) QH4-4112

    1 to 2 measures (Ohms/NC):9

    1 to 3 measures (Ohms/NC):NC

    1 to 4 measures (Ohms/NC):NC

    2 to 3 measures (Ohms/NC):NC

    2 to 4 measures (Ohms/NC): NC

    3 to 4 measures (Ohms/NC): 9.5
     
  13. SgtWookie

    Expert

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    You did not give the resistance indicated when your test probes are shorted.
    That value must be subtracted from your readings on the wires to get an accurate indication.

    Here are the specifications for the M42SP-7 on Mitsumi's site:
    http://www.mitsumi.co.jp/latest/Catalog/compo/motor/m42sp7_e.html
    Datasheet in PDF format:
    http://www.mitsumi.co.jp/latest/Catalog/pdf/motor_m42sp_7_e.pdf
    This is odd, because your measurements of 9 and 9.5 Ohms do not correspond with the values given in the datasheet. Either your motor is custom-wound, or the windings are partially shorted. Perhaps you had your meter set on too high of a scale? What WAS your meter scale setting?

    Does your motor look like the image on the website and in the datasheet?

    As far as suitability for a hobby CNC machine; it only has 48 steps/revolution, the motor has low torque and a low maximum stepping rate. Its performance would be slow and lacking in resolution. The datasheet says that it is unipolar, but that is in error - it is a bipolar motor, which means you will need to use a dual H-bridge to drive it.

    It appears the only truly good thing about the motor with regards to your application is that it was free!
     
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  14. JK-FlipFlop

    Thread Starter Member

    Jul 5, 2010
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    IT looks the same! it is that motor.
    and I got another 3 motors for my CNC from my friend (he doesn't need them),

    1. the same motor (mitsum) 4 inputs
    2. canon QH4-4115 5 inputs
    3.hosiden HP-L 0829A 6 inputs
    4.unknown 42sin-15d9na PP2-c a0905a 5 inputs

    so which driver I need to run them???
    how they work ( they have more than 4 inputs???)???

    thanks.
     
  15. SgtWookie

    Expert

    Jul 17, 2007
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    Try look up the datasheets for each of the motors.

    Google is your friend.

    It is likely that the 5-wire and 6-wire motors are unipolar steppers.

    Go through the same exercise that I had you do for the 4-wire stepper.
    Put a numbered piece of tape on each wire.
    Measure the resistance from each wire to every other wire. If the motor you are testing only has five wires, just put a dash (---) instead of NC for readings that ask for #6.

    For each motor, record:
    the MFGR and part number:

    1 to 2 measures (Ohms/NC):

    1 to 3 measures (Ohms/NC):

    1 to 4 measures (Ohms/NC):

    1 to 5 measures (Ohms/NC):

    1 to 6 measures (Ohms/NC):

    2 to 3 measures (Ohms/NC):

    2 to 4 measures (Ohms/NC):

    2 to 5 measures (Ohms/NC):

    2 to 6 measures (Ohms/NC):

    3 to 4 measures (Ohms/NC):

    3 to 5 measures (Ohms/NC):

    3 to 6 measures (Ohms/NC):

    4 to 5 measures (Ohms/NC):

    4 to 6 measures (Ohms/NC):

    5 to 6 measures (Ohms/NC):
     
  16. JK-FlipFlop

    Thread Starter Member

    Jul 5, 2010
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    shorted probes: 3 ohms

    1 to 2 measures (Ohms/NC): 40

    1 to 3 measures (Ohms/NC): 77

    1 to 4 measures (Ohms/NC): 80

    1 to 5 measures (Ohms/NC):40

    1 to 6 measures (Ohms/NC): 77

    2 to 3 measures (Ohms/NC):41

    2 to 4 measures (Ohms/NC): 42.5

    2 to 5 measures (Ohms/NC):3

    2 to 6 measures (Ohms/NC):40.5

    3 to 4 measures (Ohms/NC):78.9

    3 to 5 measures (Ohms/NC):41

    3 to 6 measures (Ohms/NC):80

    4 to 5 measures (Ohms/NC):43

    4 to 6 measures (Ohms/NC):80

    5 to 6 measures (Ohms/NC): 41
     
  17. JK-FlipFlop

    Thread Starter Member

    Jul 5, 2010
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    1 to 2 measures (Ohms/NC):70

    1 to 3 measures (Ohms/NC):140

    1 to 4 measures (Ohms/NC):140

    1 to 5 measures (Ohms/NC):140

    2 to 3 measures (Ohms/NC):73

    2 to 4 measures (Ohms/NC): 71

    2 to 5 measures (Ohms/NC):73

    3 to 4 measures (Ohms/NC):140

    3 to 5 measures (Ohms/NC):141

    4 to 5 measures (Ohms/NC):140
     
  18. SgtWookie

    Expert

    Jul 17, 2007
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    You did not mention the motor manufacturer and part number. That is a critical piece of information to include. Without it, we will rapidly become confused as to which motor is which.
    Three Ohms is too high. Either your probes are dirty, the plugs/jacks to the meter are dirty, or your meter zero is out of adjustment, or your battery is getting discharged. Use contact cleaner or 90% isopropyl alcohol to clean the connections, otherwise your readings will not be reliable. Replace the meter's battery.

    OK, for this motor, wires 2 and 5 are connected and are the "common" supply.
    The motor is wired in a unipolar configuration. It can be driven as a bipolar or unipolar stepper. The windings vary in resistance from roughly 37 to 40 Ohms.

    Since 2 and 5 are connected together, it makes it a bit more difficult to determine what are the "ends" of the coils.

    Precise readings are very important. Please record your results using at least 3 digits; ie: 42.5 - if you were actually reading 42.0 Ohms, then record that zero.

    However, you need to clean your meter probes and the jacks/plugs to get the resistance more predictable. It may be that your meter's battery is becoming discharged. If you've been using it for a while, replace the battery.

    For now, add "V+" to wires 2 and 5.

    It is not necessary nor desired for you to E-mail the results to me; posting them here is sufficient. This forum is not real-time; it may take hours or days for you to receive a reply. If you don't get an answer after a few days, simply add another reply to the end of the thread to "bump" it to the top.

    Understand that many people want help just as much as you do, and there are not a lot of people who provide it, and just so many hours available in a day.
     
  19. SgtWookie

    Expert

    Jul 17, 2007
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    This appears to be a unipolar stepper motor.
    Wire #2 is the common supply (+V).
    Your readings are not consistent. For better precision, hold the probes on the wires for at least 5 seconds before taking your reading. Some meters require more time to "settle".
    Since you did not include the manufacturer and part number, the value of your results are in doubt. Edit your post and include the MFG/part# information.
     
  20. JK-FlipFlop

    Thread Starter Member

    Jul 5, 2010
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    those are the motors:

    [​IMG]

    so for your opinion which driver I need to build for drivering this motors??

    can you give me a schematic for this driver?

    can it be only a transistor??

    thank you.
     
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