Bidirectional motor control

Discussion in 'The Projects Forum' started by jm-a, Sep 13, 2014.

  1. jm-a

    Thread Starter Active Member

    Oct 20, 2010
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  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    I would have been inclined to use Mosfets now for motor control, a little more efficient.
    Max.
     
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  3. jm-a

    Thread Starter Active Member

    Oct 20, 2010
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    Thanks a lot.

    What type of Mosfets, before spending money to my electronic parts supplier?

    jm
     
  4. jm-a

    Thread Starter Active Member

    Oct 20, 2010
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  5. ScottWang

    Moderator

    Aug 23, 2012
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    What's your purpose for the motor?
    Why you want to using manual to control the direction of motor?
    How are the V/I for the motor?
     
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  6. jm-a

    Thread Starter Active Member

    Oct 20, 2010
    105
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    Thanks a lot for your reply,

    In fact, i want only to drive a dc motor, for a roadbook: power output from a Yamaha 500 XT + bridge for dc current.

    Something simple, not only a DPDT switch to get forward and reverse ...

    For this motor, say about 20- 30 W, to be sure.. 12V output

    Actually, i've measured motor current - with no charge - result: 50 mA.
    But surge ? nominal current times 5 or 6?

    Maybe this motor is too weak, for driving roadbook rollers and map, so I'd be wise to see larger - range 20 -30 W -....

    Regards.

    jm
     
  7. ScottWang

    Moderator

    Aug 23, 2012
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    IRF840 is for high voltage over 100V and low current around 2~3A, it's not for low voltage under 40V 5A~10A, because almost low voltage mosfet always has a low resistance Rds(on) less than 20 mΩ, as 18mΩ, 14mΩ, 9mΩ, 8mΩ, 5.3mΩ, 4.5mΩ, 4.2mΩ, 4mΩ, 2.4mΩ, etc...

    Vds -- choosing a rating voltage at least 1.5 times to +V power source, but if you can choosing >2.5 times is better.
    Ids -- choosing a rating current at least 2.5 times to what load needed, , but if you can choosing >4 times is better.
    Go to mouser or some other online seller to searching the Vds/Ids as above.
     
    Last edited: Sep 13, 2014
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  8. jm-a

    Thread Starter Active Member

    Oct 20, 2010
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    Thanks a lot first,

    Like this one from my electronic parts supplier:

    http://www.reichelt.de/index.html?ACTION=3;ARTICLE=41757;SEARCH=IRL 3803



    For Rg resistor:

    http://www.reichelt.de/1W-5-1-0-Ohm...3&LA=2&ARTICLE=1770&GROUPID=6514&artnr=1W+1,5


    Regards.

    jm
     
  9. ScottWang

    Moderator

    Aug 23, 2012
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    Assuming that you using Ids=5A then
    Vds=I*R=5A* 6mΩ=30mV.
    Wds=V*I=30mV*5A=150mW.
    Normally I will using the Ids less than rating current and only 1/5 rating current.

    The current of IRL3803 is great than I bought IRF1010EPbF.
    IRL3803_Nch_30V140A200W_6mΩ.
    IRF1010EPbF_Nch_60V84A200W_12mΩ.
     
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  10. jm-a

    Thread Starter Active Member

    Oct 20, 2010
    105
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    Thanks a lot.

    Regards.

    jm
     
  11. Nykolas

    Member

    Aug 27, 2013
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    The DPDT switch in the diagram should have a centre-off position to allow the motor to come to a stop before rotation reversal. "Hesitation" switches are often used in this type of application. If you reverse the rotation of the motor without stop, your driver transistor and motor will not last long. E
     
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  12. jm-a

    Thread Starter Active Member

    Oct 20, 2010
    105
    2
    Nykolas,

    First thanks a lot for your advice.

    DPDT switch bought for this purpose is:

    http://www.reichelt.de/Switches-Roc...2&ARTICLE=105650&GROUPID=3275&artnr=HS+647+H2

    Datasheet - in german - sorry, but i don't understand ...

    https://cdn-reichelt.de/documents/datenblatt/C200/16-SERIE_600H-600NH-D.pdf


    Regards.

    jm
     
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