12VDC motor with Hall Effect Sensor

Discussion in 'General Electronics Chat' started by rfeyer, Jan 22, 2015.

  1. rfeyer

    Thread Starter Member

    Aug 24, 2014
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    I purchased the following 12VDC motor: http://www.allelectronics.com/make-a-store/item/dcm-467/12-vdc-60-rpm-window-motor/1.html for a project I listed in the projects forum (reversing motor control via DPDT relays).

    Does anyone know this motor? Or, does anyone know what the Hall Effect Sensor role would be?
    The motor is describes as a window motor, so I assumed it would be reversable. however, if I reverse the polarity, my 12V PC power source vuts off (assuming it shorts).

    Then I did some reading about Hall Effect Sensors and believe, in a window motor, it would be used to sense when the motor is at top and at bottom. Is that correct? And, if so, do you think the motor, which has 4 wires instead of 2, sends a signal when at Top and when at bottom with the two additional wires? If so, i could most likely use that if I knew how it reacts.
    Further, wouldn't you think a window motor is reversable?
    Any help would be appreciated,

    Rainer
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    The hall effect would be to sense the upper and lower limit, I would certainly expect the motor to reverse?
    If it does indeed short out in one polarity, I would remove the motor from the G.B. if possible and spin the motor with the leads open, it should be free in both directions, if it is hard to spin by hand in one direction then it indicates there is something else at play, internal diode etc, but if it is free in both, then try the supply again with the motor removed.
    Max.
     
  3. rfeyer

    Thread Starter Member

    Aug 24, 2014
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    TY Max (BTW, just listenend to Paranomia ?sp)
    I will give that a try.

    Would I be correct in assuming (not a good thing) that each rotation gives off a signal/ voltage spike in one of the other two leads and therefor, when the motor spins, I should be able to detect some voltage spike each rotation, right? And if that is correct, I should be able to use a MicroController to capture the spikes and program a routine which would do ..something.. every ..so many... spikes?
    I've been doing some reading but can't find anything other than Hall Effect sensors, seperately, which I could not apply to this 12VCD concept
    Rainer
     
  4. alfacliff

    Well-Known Member

    Dec 13, 2013
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    there will be a lot of spikes in a dc brush type motor, probably ot be able to seperate them from the rotation info. the only window motors I have seen are out of a saturn, two wires are the armature, and the other two are the fields, one for foreward, and the other for reverse.
     
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
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    If you back feed a P.M. DC motor it generates a DC voltage dependent on rpm, IOW, if the motor is rated at 1000rpm at 12vdc, the motor will generate 12vdc if back fed at 1krpm.
    Max.
     
  6. rfeyer

    Thread Starter Member

    Aug 24, 2014
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    TY for that info.
    But, specifically, is that the purpose of the Hall Effect sensor? I actually thought there would be a mechanical or optical part which senses each rotation - That seesm obviously wrong.
    So, why would the motor have 4 wires, any idea?

    Rainer
     
  7. MaxHeadRoom

    Expert

    Jul 18, 2013
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    You would need to do a little reverse engineering to find out definitely, how do you know it is a Hall sensor?
    Max.
     
  8. rfeyer

    Thread Starter Member

    Aug 24, 2014
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    on Allelectronics where they sell these there was a review by apparently a professor or such stating his students took it apart and found it to be a Hall. I left a note asking for more info, sure he is not going back to the site to see if there are new reviews, though. Also have the name of the parts checker person at allepectronics who I will call tomorrow as theys wear it is reverable.
     
  9. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    Isn't a Hall sensor a three wire device, not two? And if this is a reversible motor, you couldn't get the +V for the hall from the motor inputs.
     
  10. rfeyer

    Thread Starter Member

    Aug 24, 2014
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    It's actually a 4 wire.
    I will have to play and see if the other 2 wires have any kind of activity during run, but, the motor does run continuously when the pos neg wires are receiving 12V
     
  11. rfeyer

    Thread Starter Member

    Aug 24, 2014
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    I have not been able to check the extra 2 leads yet (need a better set up and buy some banana clips etc) but can say this:
    the 12VDC motor is definately reversable with simple reversal of polarity, so, it must be brushed.
    Tried it with a straight 12V 1A power supply. Not sure why it throws the PC supply, but will keep checking things.

    Rainer
     
  12. MaxHeadRoom

    Expert

    Jul 18, 2013
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    SMPS such as a PC power supply do not usually like a high load such as reversing a DC motor at full voltage.
    Max.
    ,
     
  13. rfeyer

    Thread Starter Member

    Aug 24, 2014
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    Something new to think about every day :)
    I will need to convert the PC power supply to a trial station with proper wiring and consider using a 12V battery such as 4 wheeler battery to power all, which could be charged with a trickler and then act as a back up as well

    Rainer
     
  14. bwilliams60

    Active Member

    Nov 18, 2012
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    I agree with Max in Post #7. If you are up to it, lets take it apart and post some pictures of it.
    Here is what I think you have and I am a little rusty on DIN schematics but I believe it is a Hall Effect motor.
    Hope this helps.
     
  15. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Just guessing, the extra wire pair could be for a thermal cut-out switch, which operates when the intended limit of movement is reached or when something obstructs the movement.
     
  16. MaxHeadRoom

    Expert

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    The Bosch circuit shows 4 wires, two for a DC motor with a magnetic sensor on the shaft and two wires for the prox sensor, they use the 2 wire system used in industrial prox where the sense wires also carry the sensor supply voltage.
    Max.
     
  17. rfeyer

    Thread Starter Member

    Aug 24, 2014
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    That is exactly the motor I have!
    Being ignorant about electronics, does this mean the two extra wires:
    - give a certain pulse per rotation which can be counted and used by a MiceoController?

    I did allow the motor to continue to rotate, and it just keeps going which must mean it does not have an inherent shut off
     
  18. MaxHeadRoom

    Expert

    Jul 18, 2013
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    If it is the type of sensor I think it is, it still operates as a sensor when a suitable input maintains a small current in order for it to register a low and still maintain circuit operation, some of the industrial types even have a small LED that show it is ON.
    A micro controller should be OK possibly with a pull up resistor.
    The sensor probabally indicates the up and down extremes in this case.
    Max.
     
  19. rfeyer

    Thread Starter Member

    Aug 24, 2014
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    Sorry MaxHeadroom, I don't understand:
    So, you are saying that the sensor 'expects' a low voltage input to do what? In other words, it is asking for information (the sensor being inside the motor?) rather than giving information?
    I would have hoped the two wires actually give/output changes in voltage which I then could use to say: at this amount of votlage or this amount of recurrences, do 'that'. I am possibly in dream land as it would make the high and low cut off easier for me (though I can do with SPDT switches as well)

    Rainer
     
  20. MaxHeadRoom

    Expert

    Jul 18, 2013
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    There are basically two types of these sensors, 3 wire and 2 wire, the 3 wire provide a +V, -V and an output from an open collector transistor.
    The 2 wire type require a small operating current from the sensing device to operate, when they switch from 1 to 0, there is still a small residual current flowing in order to keep the circuit in operation, as long as the low is sufficient for the sensing end to see this as a 0, everyone is happy.
    Although I have used these many time in PLC's I have not as yet tried one on a microchip etc.
    They are no good where a load has to be switched, relay etc, the 3 wire do this using the open collector.
    http://www.fargocontrols.com/sensors/inductive_op.html
    Max.
     
    Last edited: Jan 23, 2015
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