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Marks dog door

Discussion in 'General Electronics Discussion' started by [email protected] .au, Feb 25, 2016.

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  1. mlenehan@bigpond.net .au

    [email protected] .au

    63
    2
    Feb 25, 2016
    Hi I am electronically illiterate so you might have to go slow on me please . My project requires a 12 v circuit design please .
    The idea is to open and close small dog door with a 12v 3 amp actuator
    The actuator takes 40 seconds extend and 40 seconds to retract. I hoping to be able to push a switch / button which will connect to your circuit suggestion which will extend the actuator rod and to its full length Which takes 40 secs then retract the actuator rod without pushing the switch / button a second time ? Your help would be much appreciated . Thanks Marks dog door.
     
  2. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    How much do you want to learn?

    In the most basic sense, you will need (or should use):
    - an H-Bridge to control the actuator forward and reverse. (Please provide actuator specs)
    - limit switches for Open and Closed position. (Don't rely on timer here)
    - Timer (Can be made with a 555 timer and some spare resistor / capacitors. Time will be adjusted by swapping out parts)
    - Logic. This can be done with relays or with ICs .

    You need a pair of 'latches'. Push the button and the the device latches 'open' . Once the door hits the open limit switch the latch releases and a timer starts. When the timer expires it triggers the close latch which will close the door. Once the door hits the closed limit switch, the latch releases.
    (Ideally, the push button will also release the 'close latch' to prevent the door from closing or to re-open the door)
     
  3. Alec_t

    Alec_t

    2,902
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    Jul 7, 2015
    You will also need some way of preventing your dog from trying to pass through the doorway when the door is only partly open ;).
     
  4. mlenehan@bigpond.net .au

    [email protected] .au

    63
    2
    Feb 25, 2016
    image.png image.png Thanks for quick reply I have pictures below showing specs of actuator - I went to local elec store and they suggested you guys image.png image.png
     
  5. Gryd3

    Gryd3

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    Jun 25, 2014
    Thanks for the specs. That's a LOT of force for a dog door, you may need to put a safety in place to prevent fido from getting pinched in the door as it closes.
    Built in limit switch is good though... do you know if there is one on the end of each direction of travel?
     
    KeithM likes this.
  6. Alec_t

    Alec_t

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    Jul 7, 2015
    A much safer option would be a pet door which is pivoted and has a locking catch which is released by the presence of a coded tag on Fido's collar. This type is available off-the-shelf.
     
    hevans1944, Osmium and Gryd3 like this.
  7. mlenehan@bigpond.net .au

    [email protected] .au

    63
    2
    Feb 25, 2016
    I think the rod extends till it reaches its full length then stops and when it retracts it goes all the way back in
     
  8. mlenehan@bigpond.net .au

    [email protected] .au

    63
    2
    Feb 25, 2016
    I think the rod extends to its full length then stops and when it retracts goes all the way in
     
  9. mlenehan@bigpond.net .au

    [email protected] .au

    63
    2
    Feb 25, 2016
    If possible could you draw the circuit labelling the capacitors etc and I'll show to my local radio shack guys
     
  10. Gryd3

    Gryd3

    4,098
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    Jun 25, 2014
    You have a good radio shack then... the ones in Canada shifted away from that kind of thing and sell TVs and cell phones now...
    Ask them for a 4017 and they think it's a product SKU...

    Anyway, if the limit switches are built in, the simplest thing would be a timer and DPDT relay... the relay will be used as an H-Bridge... it's normally closed position will cause the actuator to close. If the limit switch stops the current, then you can simply leave it like this.
    When you start the timer, the relay will toggle holding the actuator in the open position... once the timer expires the relay revert back.
    This option REQUIRES that the limit switches turn the actuator off and should be tested first!

    Depending on the time you need, a simple 555 one-shot timer should do it for you.
    Please test your actuator and do a quick search for a timer and let us know what you find/draw up. We can help refine it from there.
     
  11. mlenehan@bigpond.net .au

    [email protected] .au

    63
    2
    Feb 25, 2016
    Hi again it's actually called Jaycar but I thought that would be an unfamiliar name for you . I am in Australia thanks for being patient with my project . The actuator is being shipped from an eBay purchase so when it arrives I will check it out and get back to you with some more details Talk soon Thanks So Much Mark
     
    Gryd3 likes this.
  12. mlenehan@bigpond.net .au

    [email protected] .au

    63
    2
    Feb 25, 2016
    Hi I'm back Gryd3 is helping me with the actuator - it arrived today and works as expected but has a remote control that I'm hoping will assist our efforts to achieve opening closing with one button push -I have taken photos herewith that might help Thanks Marks Dog Door image.jpeg
     

    Attached Files:

  13. Gryd3

    Gryd3

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    Jun 25, 2014
    Thank you for pictures. It would appear as though you either need to fit your own limit switches on the door/actuator, or cross your fingers and hope the built-in limit switches on the actuator are 'broken out' so that there is a wire you can use to read their current state. (It did not look like it in the picture)
    It there are two limit switches inside the actuator that go open circuit when reached, then you can use this controller just fine, but remember this device will continue to put out voltage to the actuator ALL THE TIME, unless you manually switch it off or put it on a timer. This should not negatively affect performance if all you are after is the open/close action.
    You must be CERTAIN that providing continued power to the actuator when it reached the end of it's stroke is fine, or you will need those limit switches.
     
  14. mlenehan@bigpond.net .au

    [email protected] .au

    63
    2
    Feb 25, 2016
    Hi thanks for your advice and interest I will post a picture when we are operational thanks again Mark
     
  15. mlenehan@bigpond.net .au

    [email protected] .au

    63
    2
    Feb 25, 2016
    Hi gryd 3 I have decided to go back to your original suggestion of 555 timer and dpdt etc I have posted some pictures of some I think will work ??
    Thanks Mark
     

    Attached Files:

  16. Herschel Peeler

    Herschel Peeler

    401
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    Feb 21, 2016
    How long will it take the dog to realize the door is open and get through the door?
    What happens if the dog tries to push the door open early?
     
  17. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    I'd certainly call that a good start.
    You have the components to trigger the door to open, as well as a timer and a relay to change the direction.
    I think the simplest way to build this project is to rely on the limit switches, then use the timer to open the door.
    When the timer is triggered, the door will open, and continue to open until it hits the limit switch. This limit switch will cut power to the actuator and stop the door from opening too far. Once the timer expires, the door will begin closing and once the bottom limit switch is hit, it will again, cut power to the actuator to stop the door from closing too far.
    We still need to consider safety though! You can use a 'break-beam' sensor to make sure nothing is in the door-way when it begins to close for example. We don't want this to close on anyone...
     
  18. mlenehan@bigpond.net .au

    [email protected] .au

    63
    2
    Feb 25, 2016
    Hi again Thanks for your help with regard to safety I'm ok with no beam as I can watch the door from where I sit . But I'm not sure how the circuit is to be wired - I will need a very idiot proof diagram for the wiring - I will send what I am imagining it to be and perhaps you could tweek it for me Mark
     
  19. mlenehan@bigpond.net .au

    [email protected] .au

    63
    2
    Feb 25, 2016
    image.jpeg
     
  20. mlenehan@bigpond.net .au

    [email protected] .au

    63
    2
    Feb 25, 2016
    Hi again I'm probably going to need to be babied through this if you can please
    Thanks Mark
     
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