please help drive for stepper motor &mosfet

Discussion in 'General Electronics Chat' started by mastertiger, Jul 9, 2012.

  1. mastertiger

    Thread Starter New Member

    Jul 9, 2012
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    hi
    i make 4 axis cnc machine so,
    i use 4 stepper motor 4.6A i make drivers for every motor
    [​IMG]

    and this site have every detail
    http://www.instructables.com/id/Easy-to-build-CNC-Mill-Stepper-Motor-and-Driver-ci/CEVVKDOH27LSH4K
    i use 60n06 as mosfet
    i use unipolar stepper motor 6 wires
    i make circuit for limitation the current
    [​IMG]
    this site for details
    http://www.divms.uiowa.edu/~jones/step/current.html
    i have some problem problem
    1- i can know how to calculate R2
    2- 60n06 heated so much
    3- voltage across motor only 2.5v i use 24v power supply & voltage come out from r1=17v
    i need to know why voltage be like that
    please help
     
    Last edited: Jul 13, 2012
  2. tracecom

    AAC Fanatic!

    Apr 16, 2010
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    Here is a more legible schematic.
     
    mastertiger likes this.
  3. mastertiger

    Thread Starter New Member

    Jul 9, 2012
    24
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    thanks
    do you know best mosfet can i used for 12v & 5A stepper motor
     
  4. tracecom

    AAC Fanatic!

    Apr 16, 2010
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    I am not an expert, but I have used IRF44N, and IRL44N (when logic level drive is required.) There are others here with more experience.
     
  5. mastertiger

    Thread Starter New Member

    Jul 9, 2012
    24
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    i used irf 840 before 60n06
    it is heated more than 60n06
    i need high power mosfet
     
  6. mastertiger

    Thread Starter New Member

    Jul 9, 2012
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    i measure the voltage out from mosfet it 7v while input power supply 24v
    when i connect motor and limitation circuit voltage be 2.5v
    i need to know why voltage be like that
    please help
    mosfet in circuit work as switch why regulate voltage .
     
  7. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    You need to use a logic level mosfet.. Not a standard one.
     
  8. gerty

    AAC Fanatic!

    Aug 30, 2007
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    How much current can this power supply provide?

    Is that 4.6a per motor, or 4.6a total?
     
  9. mastertiger

    Thread Starter New Member

    Jul 9, 2012
    24
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    i used 60n06 logic level mosfet
    i have 3055 &15n06 logic mosfet do you think it will work fine
     
    Last edited: Jul 9, 2012
  10. mastertiger

    Thread Starter New Member

    Jul 9, 2012
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  11. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    Why not change the zener diode to a 12V one and then a standard Nmosfet can be used?

    How are you measuring the output voltage of the mosfet when it should be connected to ground?

    With the CD4016 and CD4028 providing the stepper logic in this circuit, there is no amperage control to the motors. This is the reason to use regular step motor divers for a circuit like this. Fewer components and more control of the motor is the result of using a stepper driver chip.
     
  12. mastertiger

    Thread Starter New Member

    Jul 9, 2012
    24
    1
    [​IMG]

    first think i need to understand zener diode here do what
    i measuring the output voltage of the mosfet between output of mosfet and +dc when gate open
    i use this drive (very simple ) only problem i have with mosfet
    i make current limitation circuit it run nice
    but problem with voltage
    i use 24v power supply and voltage across motor only 2v
     
  13. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    The zener in your schematic allows only what ever voltage it is rated at to the rest of the circuit. By changing the zener value it changes the voltage available to the circuit. The chips you have chosen will work at 12V and that will also give 12V for the mosfet gates.

    Still don't understand how you are measuring "mosfet output". The mosfets are not "outputting" anything. The S(source) is connected to ground/common, or should be in a unipolar stepper drive. So when measuring from +V to ground that should be your supply voltage.
     
  14. mastertiger

    Thread Starter New Member

    Jul 9, 2012
    24
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    i change zener but nothing change
    i measure the voltage out from ic 4028 to mosfet 1.5v
    that is make mosfet heated so much and cut voltage
    i will use operational amplifier to make it 5v
    i measuring voltage between output of mosfet and +v supply
    resistance in mosfet still high because voltage in gate not 5v
    and cut voltage to 7v
    do you know best amplifier can i use for (27v power supply)
    max v for 741 is 22v
    thanks
     
  15. SgtWookie

    Expert

    Jul 17, 2007
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    You should try disconnecting the 4028 outputs from the MOSFET gates (connecting the gates to the source terminal temporarily to protect them) and then measure the voltage at the output of the 4028. You should then see the output voltage rising to the same as Vdd when that particular output is selected.

    One of the problems is that you are using MOSFETs with a large Qg (total gate charge) and are trying to charge/discharge them from a 4000 series CMOS part, namely the 4028. These CMOS parts are efficient compared to, say, the old TTL, but rather anemic - this results in the MOSFET turn-on and turn-off times being quite slow. In this situation, having slow turn-ON times isn't so bad, as it will take awhile for the current flow to build through the motor when it's first turned on. It's the slow turn-off time where heat is generated.

    It's also possible that you might be experiencing ringing on the gates, as the schematic doesn't have gate resistors shown, nor does it show bypass capacitors for the CMOS ICs.

    When a MOSFET fails, it frequently fails with the gate shorted to the drain. This failure mode would likely destroy your 4028 as well as the MOSFET. This is why I asked you in the beginning to see if the voltage on the 4028 outputs comes up to Vdd or not.
     
  16. mastertiger

    Thread Starter New Member

    Jul 9, 2012
    24
    1
    i disconnecting the 4028 outputs from the MOSFET gates
    i measure the voltage at the output of the 4028 1.5v
    vdd = 6v
    so 4028 destroy or i need to amplified voltage form it to mosfet
    what is number of mosfet can i use with 4028 and work well ?
     
  17. mastertiger

    Thread Starter New Member

    Jul 9, 2012
    24
    1
    i changing 4028 &4516
    and have same result 1.5v output from 4028 & vdd=6v
     
  18. SgtWookie

    Expert

    Jul 17, 2007
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    OK then, check your wiring because something is causing the outputs of the 4028 to get loaded excessively. If your Vdd=6v, you should see that on the output.
     
  19. mastertiger

    Thread Starter New Member

    Jul 9, 2012
    24
    1
    i make the circuit again on text board vdd=6v(4028&4516) vout from 4516 to 4028 = 6v
    vout from 4028 = 1.5v
    i connect wire exactly like photo [​IMG]
     
  20. mastertiger

    Thread Starter New Member

    Jul 9, 2012
    24
    1
    i take signal from 4028 to 741 and make it out 5.5 v by non inverting amplifier connection
    [​IMG]
    but if i connected to mosfet 60n06 it heated so so much
    is this because the different in speed between 4028 & 60n06
    or what
     
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