Coop door opener with 2 way 12VDC motor

Discussion in 'The Projects Forum' started by rfeyer, Jan 26, 2015.

  1. rfeyer

    Thread Starter Member

    Aug 24, 2014
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    I am expanding to project forum though the motor used here is the same 4 wire ?Hall effect sensor motor discussed under 'chat'.
    Using the motor simply as a 2 wire (and I checked to see that reversal of polarity will reverse the motor), i have the following project:
    -Coop door in a frame sliding up and down.
    -At top and at bottom will be a mechanical SPDT simple switch to turn motor off if either is activated (top and bottom limiter switches).
    -motor should be controlled from a MicroController (I am using a WebControl8.0 for this project) which has TTL digital outputs at 5v 20mA

    attached is my SIMPLE schematic (I am very green in electronics and have problems reading diagrams, but am learning).

    Disclaimer: I have had excellent help at another forum from some great people, but at the end I am too green to understand the comments/ suggestions made. I hope this OK.

    Rainer
    New-Hendoor.jpg
     
  2. Reloadron

    Active Member

    Jan 15, 2015
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    Maybe I am not looking at this correctly but I see a few issues. I remember the motor thread and if I am not mistaking these motors draw some current. I see your 12 volt supply going to your relay and switched by a transistor. That transistor will be handling the full motor current, you are planning for that correct? The door top limit switch doesn't do anything as the line across the relay contacts (top left, lower right) is across the switch contacts as I see it drawn. The lower limit switch as drawn is right across the relay NC contacts which as drawn I don't see working.

    While I am not at all familiar with the WC8 micro controller you may want to think about using the limit switches to send door position (door up or door down) to the uC. Let the uC handle any timing functions as to how long the door is up or down and when to open or close the door based on other sensor inputs. You may want to consider using an H-Bridge capable of the motor current rather than a relay.

    Just My Take....
    Ron
     
  3. wayneh

    Expert

    Sep 9, 2010
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    Search this site for "coop". There have been several good threads on this topic.
     
  4. rfeyer

    Thread Starter Member

    Aug 24, 2014
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    OK That helps!

    I changed it so the up and down limit switches are located at initial power source as well as lead going to motor. Would that make more sense and hence be acceptable/ workable?

    New-Hendoor.jpg
     
  5. #12

    Expert

    Nov 30, 2010
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    Is your goal to make a coop door or to use a microprocessor chip?
    Be aware, the square with the light sensor is peculiar to this exact circuit. It is not the usual CdS photosensitive resistor. It is an after market device called a, "Night Watchman".
     
    Last edited: Jan 26, 2015
  6. rfeyer

    Thread Starter Member

    Aug 24, 2014
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    AAC Fanatic,
    my goal is to have a door slide up and down, stop at the end of either direction, use a 12VDC motor and the operation to be controllable from a MicroController - Ardunio would be the closest name I could relate to the WebControl8.0 (although WebControl has a Netowrk connection) which I am already using for temp readings etc.
    I unfortunately can not understand the schematic well enough to understand if my drawing is essentially correct or not.
    However, it would help me to know if my second ddrawing is now functional without blowing up either the coop or the motor or the WebController

    Rainer

    New-Hendoor.jpg
     
  7. wayneh

    Expert

    Sep 9, 2010
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    The emitters of your transistor should be at battery ground. Just move their positions in the circuit.
    I don't see much purpose to the diodes, other that the one across the poles of the relay coil.
     
  8. rfeyer

    Thread Starter Member

    Aug 24, 2014
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    OK - I changed the position of the transmitters to the negative/ ground - would the position of the emitter now have to be reversed as well compared to the collector?
    New drawing:
    New-Hendoor.jpg
     
  9. strantor

    AAC Fanatic!

    Oct 3, 2010
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    I saw my name in your image title and thought "what the heck? I didn't draw that. And I don't think I've ever heard of a 'night watchman'." So I searched "night watchman" here in the forum and found this old thread. Apparently I have heard of one, and drew some hideous circuit with it. And yours was much prettier. Hence why it is displayed here in your signature format with my name in it. Teamwork, from 3 years ago! High Five!
     
  10. rfeyer

    Thread Starter Member

    Aug 24, 2014
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    Also, is the diode across the relay core facing the correct direction? Seems as it should allow flow from positive to negative, but I have it blocking from positive to negative, no?
    And, of course, if someone could look at the placement of the transistors, that would be great!
     
  11. Reloadron

    Active Member

    Jan 15, 2015
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    The diode position is fine. The only time the diode does anything is when power is removed from the relay coil and the coil field collapses. The diode in this case is being used as what is called a "flyback diode". As to the transistors? I suggest you go back to #12's post #5 and look at how the relays are used. The merit to this design is unlike a DPDT relay where one set of contacts is always closed using two SPDT relays makes for a much better and cleaner configuration for doing polarity reversal. Also, as I mentioned earlier you need to know your motor current under a load. The beauty of using two SPDT automotive relays as shown in $12's post is they typically handle 30 to 40 amps DC.

    Ron
     
  12. rfeyer

    Thread Starter Member

    Aug 24, 2014
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    I do appreciate all the help. However, as mentioned, if I could understand/ read the diagrams I would most liekly agree with you, but I can't/ don't understand the diagram
    The load of the motor: it cuts off at 10A.
    WOuld it still be possible to get help with my diagram, i.e.: is positioning of transistors OK? Does the diagram make sense?
     
  13. Reloadron

    Active Member

    Jan 15, 2015
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    What is the diode on Power + for? Your drawing shows a 5 Amp supply and you mention a motor that can draw 10 Amps? Again, if your motor can at any time draw 10 amps you will need a transistor in there that can handle 10 Amps plus some headroom. Overall as drawn it is just not a very good or practical design you seem to want to pursue.

    Ron
     
  14. #12

    Expert

    Nov 30, 2010
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    I don't forget the people that help me.
     
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  15. wayneh

    Expert

    Sep 9, 2010
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    Yes the emitters should point towards ground and the collectors towards your loads. As noted, the diode at the relay is fine.
    Your transistors need to handle the current of the relay coil only, not the entire motor current. That's what the relay is for.

    That said, I don't quite follow how that relay is configured. If you've tested that or your sure it's good, it doesn't matter if I don't quite follow.
     
  16. Reloadron

    Active Member

    Jan 15, 2015
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    This was his last drawing:

    Weird Motor.png
    I have no idea what the diode on top is for? It will drop about .7 volt and see the full motor current. Then there is the transistor below it which will handle the full motor current and has the collector tied to the negative supply side? My best guess here is since using a DPDT relay to switch polarity the motor is going one way or the other but there is no stop using a relay like that. No clue what the resistor in the emitter leg is for? makes no sense. Finally I don't get the logic turning the relay coil on. As drawn I don't see this circuit working. #12 posted a good circuit that can be modified to meet the needs of what needs done.

    Ron
     
  17. #12

    Expert

    Nov 30, 2010
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    No, the diagram doesn't make sense. That's why nobody can tell what you're doing.
    This is like posting sheet music for me. I can't read those dots and flags, so tell me how to play Stairway to Heaven.
     
  18. wayneh

    Expert

    Sep 9, 2010
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    Yeah, I misread it because it is so non-standard. My bad. Reloadron got it right. I usually just stay quiet when I can't understand something. Stairway starts in Am if I recall. My hands remember, but my brain, not so much. Randy California of Spirit wrote the famous riff.
     
    Last edited: Jan 26, 2015
  19. Reloadron

    Active Member

    Jan 15, 2015
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    Very, very carefully. :) I have to remember that. My brother is an accomplished musician, one of my sisters can play piano. I missed that gene or DNA thing. Me, I could spend a decade at Juilliard’s renowned Music School and still never be able to read music or play an instrument.Just isn't going to happen.

    Ron
     
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  20. #12

    Expert

    Nov 30, 2010
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    One of my biggest shames. I thought I could do music while staying illiterate.
    Illiterate means the same thing in music and electronics. If you don't learn the language, you are doomed to play cover songs for the rest of your life, and still not understand the details.
     
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