Help with DPDT, 2 shut offs and polarity reversal

Discussion in 'The Projects Forum' started by rfeyer, Aug 24, 2014.

  1. rfeyer

    Thread Starter Member

    Aug 24, 2014
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    Hello all,

    I have the following project in mind:

    2 phase Motor receives power
    Motor pulls a line appr 2 feet at which point the line triggers a shut off switch
    Motor is inactive until activated by the same on switch, but this time reverses polarity and releases the line for the same distance, triggers a second shut off switch and is again inactive

    I am using a 2-phase 12V motor and a DPDT Relay (DYL 2S-D12) and 2 shut off switches.

    the power is supplied via an IP 110V outlet to which a 20V transformer is plugged into.

    Remotely, I will turn the IP outlet on to power the relay and will turn the power supply off after each function.

    Explanation:
    I have a trap door on a chicken coop which I wish to open in the morning and close in the evening remotely when not at home.

    Any help would be appreciated!
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    If this is a two phase synchronous stepper type motor, you could use the circuit shown in the SloSyn KS series of motors, Use the switch SPDT or DPDT shown and insert a Limit switch for each direction immediately after the fwd and rev contacts for each direction.
    Or post more details of the motor.
    Max.
     
    Last edited: Aug 24, 2014
  3. inwo

    Well-Known Member

    Nov 7, 2013
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    Easy enough to do, what you ask, but is it wise?
    You don't know the state of the door. Each time you power the outlet it will change.

    So it could easily get out of step.

    What is a two phase motor?
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
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    The circuit I refered to overcomes the possibility of wrong function when power off/on.
    One version of a 2 phase motor is a AC synchronous motor using a unipolar stepper motor with a series resistor and cap for one winding, similar to a split phase AC motor.
    Most of the stepper manufacturers also made these for use on 120v 50/60 hz and advantages were almost instant stop/start and synchronous running.
    Max.
     
  5. rfeyer

    Thread Starter Member

    Aug 24, 2014
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    I am obviously not very literate in the electrical world, my apology.

    The motor I have only has two wires, by correction I believe it should be single phase, then, correct?
    When the door reaches the bottom, it activates cut off switch number one.
    When at the top, it should activate cut off switch # 2.

    I have been looking at schematics and videos for days, can't gegt it into my head.

    Also, I don't really know how to apply a schematic to the actual relay which is mounted and does have numbers 1 through 8

    I know, I a need a lot of help
     
  6. inwo

    Well-Known Member

    Nov 7, 2013
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    Sounds like a DC motor that is reversed by swapping the wires.

    I would suggest two outlets. One for open and one for close. Then all power could be off between cycles.
     
    Last edited: Aug 24, 2014
  7. MaxHeadRoom

    Expert

    Jul 18, 2013
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    As INWO intimated, it is necessary to find out the type of motor you have, does it appear to have a couple of carbon brushes?
    You mention using a plug in transformer which is AC unless a Wall Wart DC supply?
    Max.
     
  8. rfeyer

    Thread Starter Member

    Aug 24, 2014
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    It is certainly a DC motor, that I know.
    I really only have one outlet available, as it is controlled over IP.
    I was hoping that the power to the motor could be reversed via the DPDT - I did read something like that years ago when I purchased these for the saltwater fish tank (automated fill up system) but can not find the information anymore.

    Rainer
     
  9. rfeyer

    Thread Starter Member

    Aug 24, 2014
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    BTW, it is an 8 pole DPDT relay, not six, if that helps?

    Rainer
     
  10. inwo

    Well-Known Member

    Nov 7, 2013
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    We can help once all the questions are answered.

    The relay seems to be an 8-pin 2 pole relay. :confused:

    If using only one relay the limit switch must carry full motor current.

    If that's ok, and you're not worried about it getting out of step, then an impulse relay or circuit, and 12vdc power, are the only other things you need.

    The relay controls motor direction, and impulse relay (FLIP-FLOP) remembers which way to run.
     
  11. inwo

    Well-Known Member

    Nov 7, 2013
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    Do you have power available when outlet is off?
     
  12. rfeyer

    Thread Starter Member

    Aug 24, 2014
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    The relay, then has 8 pins. This particular one, DYL 2s-D12 pas two row of pins, 6 of them vertical, 2 horizontal (guess it depends how one holds the relay) :)

    The point of this operation would be to use an IP outlet, which I can turn on, or turn off over the internet/ LAN. So, I am guessing that continuous current is not that possible?

    I could possibly get a second of these relays (May even have another in my basement as I did have 2 several years ago).


    Rainer



     
  13. inwo

    Well-Known Member

    Nov 7, 2013
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    Here is one I modified from another coop door project.

    Relay numbers from memory. (octal)

    12V supply not shown. It would have to switch "on" cleanly to ratchet.

    Each time power comes on, motor will run til opposite limit.

    Downside is not knowing open or close.:(

    Switches can be wired differently without diodes.
     
    Last edited: Aug 24, 2014
  14. inwo

    Well-Known Member

    Nov 7, 2013
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    Possible way with DP limit switches and two standard relays.

    Forward or reverse relay remains latched until power is cycled.
    Direction is remembered by limit position.
    Two more relays will eliminate need for special limit switches but increase complexity of circuit.

    Starting mid stroke will need some capacitance across F or R.
     
  15. rfeyer

    Thread Starter Member

    Aug 24, 2014
    126
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    Well,

    I am thinking that is a little above my brain cage size.
    I was hoping I could accomplish this with the relay and a possible H-Bridge (something I just read about today).
    When it gets to Radgets and diodes I would have to take another semester of Electrical studies (and I haven't even had one semester so far :) )

    So, is it not possible with my relay and an H-Bridge? Or something similar? If not, then I will have to revert to 2 bottles of fluid suspended by a wheel (old school) but would rather use a motor than 2 water pumps :)

    Rainer
     
  16. inwo

    Well-Known Member

    Nov 7, 2013
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    Reversing the motor with the one relay you have is no problem.

    The problem is how to close the door when outlet goes off, and there is no power.

    Would a 12v battery be something you'd consider? (or other power that stays on)

    Then outlet on = open, and off = closed. Or vice versa.
     
  17. rfeyer

    Thread Starter Member

    Aug 24, 2014
    126
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    I was hoping that would be the point of the relay (Again, my ignorance):
    The relay is triggered with being given power (let's say this triggers toe door to close).
    Once the door is down it will activate a shut off switch and the motor stops. I now stop giving power.
    The next time power is turned on, I was hoping to go in reverse, go to top, another shut off stops the process and power is taken off again.
    I could possibly do this by making a round disk to which a rope is attached, that way the motor does not have to be reversed (when disc is rotated to 6, rope pulled most and door open, when disk is at 12, door closed - I'm sure you know the concept).
    But then I would still have to have a mechanism where the door shuts off power at the bottom and top.
    Hmm, I may be asking too much?
     
  18. inwo

    Well-Known Member

    Nov 7, 2013
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    My diagram does pretty much what you explain.

    I can figure out how the same limit switch that stops the motor, will also tell motor to go in the other direction, next power cycle.

    Actually I can, but it won't wait for power cycle.:(

    If it's just the diagram that you have trouble with, someone more artistic than me could draw a picture.

    How does battery power, special relay, or double end switches sound?

    Don't give up. Someone else may have a better plan.:D

    edit:
    The last drawing may look complex, but it's just two of your relays, and two switches on each end. (or two pole switch)[​IMG]
     
  19. inwo

    Well-Known Member

    Nov 7, 2013
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    I believe you will run into the same constraints with a mechanical solution.

    Unless you have a counter weight that closes door when power is removed.

    A switch than cuts power must also set up condition for reversing (or continuing for close-disk method) motor. But not immediately, only next power cycle.
     
  20. rfeyer

    Thread Starter Member

    Aug 24, 2014
    126
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    I will do some research on what a ratchet does, then will try to understand your schematic - it is actually looking a little easier, since I see where 2 and 7 are attached, though the rest I don't understand.

    More research needed. :)

    Rainer

    would be nice to make it work, though.
     
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