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Building safety garage door project.

Discussion in 'General Electronics Discussion' started by Steve-o, Mar 18, 2016.

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  1. Steve-o

    Steve-o

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    Mar 18, 2016
    Hi guys, I just found this website today and was wondering if I can get some help off of it. I'm doing a safety door mechanism for a school project and I am having some trouble creating a schematic that would allow to open and close a model garage door. I have everything made and the motor works fine, I can change the polaritie with a rocker switch that I wired up.

    My problem now is limiting the door to a certain point so that it won't rip off, I have acquired 2 limit switches and 2 relays to help with this.

    Pretty much I have a sensor that once is activated sends a signal to the motor to make it start closing the door. I have a limit switch at the top and a limit switch at the bottom for limits of movement. I would then like to press a button that would open the door back and pretty much act as a 'reset' to what it originally was.

    I honestly am having some trouble drawing up this schematic and was wondering if you guys have any input on this with maybe how the relays and limit switches are wired. I would greatly appreciate the help. Thank you if you can.
     
  2. Gryd3

    Gryd3

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    Jun 25, 2014
    More than one way to do it.
    Are the limit switched normally open or normally closed?

    Simplest way to do it...
    If you have a 2-way rocker switch:
    - Put a normally closed relay contacts in series with the output of the rocker switch.
    - Put a limit switch on the door, and wire it to the relay.
    When the limit switch is pushed, the relay toggles which disconnects the output of the switch from the door.
    The switch will no longer work in this direction until the limit switch is released... but the 'second' output from the switch will still move the door in the opposite direction.
    Simply repeat this circuit once more and you have protection from the up and down movement.
    Figure out the 'logic' then make a sketch... you can draw a schematic with 'logic' blocks until you determine how to do each task by itself.
     
  3. Minder

    Minder

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    Apr 24, 2015
    I am assuming you are looking for a safety limit?
    Similar to a G.door to reset to the up position or a blocking/ hazard detection.?
    M.
     
  4. Steve-o

    Steve-o

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    Mar 18, 2016
    Yes kinda similar.
     
  5. Steve-o

    Steve-o

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    Mar 18, 2016
    Thanks, I'm going to try that out in the few couple of days. I'll let you know how it goes
     
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  6. Gryd3

    Gryd3

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    Jun 25, 2014
    Sounds good. Please either draw a diagram yourself, or ask for one just to be sure we are all on the same page ;)
     
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  7. Steve-o

    Steve-o

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    Mar 18, 2016
    Hey sorry to bother you, I'm drawing the block diagram right now for a quick rough draft, wouldnt it make more sense to have the relay wired to the limit switch in series and then to the input of the rocker switch? Or maybe I'm just not seeing something, I could be totally wrong. Thanks
     
  8. Gryd3

    Gryd3

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    Jun 25, 2014
    Perhaps. Although to be honest, I think we both know how we want it wired but are wording it differently.
    Are the limit switches normally open or normally closed?

    If you use a normally open limit switch, you should use it to trigger a relay that is in series with one of the outputs of the two-way rocker switch.
    This way, if the switch is set to 'up' and the limit switch is hit, the relay will break the 'up' portion of the circuit.
    If you use a normally closed limit switch, then you can simply put it in series with one of the outputs of the two-way rocker switch... same outcome, but one less part because the switch itself will directly break the circuit.

    If I misunderstood, then show us the drawing anyway and we can ensure we are both on the same page.
     
  9. Steve-o

    Steve-o

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    Mar 18, 2016
    I think I understand now. The NC limit switch would trigger the relay off which is connected with the output of the rocker switch. Makes sense. Cuts off the power, Thank you I'll try that out
     
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  10. Steve-o

    Steve-o

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    Mar 18, 2016
    Hi, this is what I drew up, let me know if I'm on the right track, thanks!

    http://imgur.com/COxUT7v
     
  11. Gryd3

    Gryd3

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    Jun 25, 2014
    Not quite what I had in mind. It looks possible to attempt to operate the door in both directions at once..
    Can you provide the 'current' circuit diagram for the door?
    The limit switch and relay are only there to interrupt the *current* mode of operation while allowing the other one to still function. We need to make sure that hitting a limit switch does not kill the whole thing ;)

    (That.. and I think the relay's are connected backwards... the + and - are usually used to trigger it, almost never as an output. COM, NC, and NO are used as outputs.)
     
  12. Steve-o

    Steve-o

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    Mar 18, 2016
    Could I go from 12vpostive to limit switch and then to the + of the relay? But the thing is then I would need to incorporate the signal from the sensor to the output of the relay... Hmm.. My limit switches can be either NC or NO same with my latching relays so I just need to figure how to I corporate everything without confusing myself haha. Sorry if my confusion is confusing you as well :p
     
  13. Gryd3

    Gryd3

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    Jun 25, 2014
    Haha. no problem.
    That's why I asked for the current configuration, because the idea most certainly was 12V to the Limit Switch, then to the + of the relay. The Limit Switch would then control the relay.. We need to identify how we can put the Relay's NC or NO connection to use with the existing system to interrupt the 'currently selected' movement without disabling the whole door altogether.
     
  14. Steve-o

    Steve-o

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    Mar 18, 2016
    http://imgur.com/BrVsNvV I think I'm getting closer? Could be wrong with the relays and whether they are NC or NO depending on my signal.... But in regards to the current I have nothing too high, I think I was receiving approx 100mA from the supply
     
  15. Gryd3

    Gryd3

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    Jun 25, 2014
    Untitled.png
    I was thinking something like this... but it depends on how the existing system is wired as well...
    The idea here is that you have two relays. One for Forward Limit and on for Reverse Limit.

    The Forward Limit Relay has it's + connected to the Forward Limit switch, and it's - connected to ground. The limit switch itself simply goes to power.
    Once the limit switch is hit, it will cause the relay to change.
    The COM of the relay will to the output of the 'direction' switch, and either the NO or NC will continue on where the direction switch used to go. We will be using this relay to sit in-between the switch and what it originally controlled to intercept and interrupt it when the limit switch is hit.
    It is important to know the 'current' wiring of the door though, as we may need to add additional logic to this if the original switch used a 'momentary' type .
     
  16. Steve-o

    Steve-o

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    Mar 18, 2016
    I think I have finally figured it out, have been working on it today for quite a bit. It has come to my attention that I wouldn't really need a relay in the reverse direction but only a limit switch from my rocker, because I will switch it to go reset to the original position, I'm the one manually doing it. The only thing for me would to have the relay on the forward side since its latching, do you agree or would you like to see my rough drawing ?
     
  17. Gryd3

    Gryd3

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    Jun 25, 2014
    I always prefer seeing drawings ;)
    What you say makes sense though, lets iron out the electrical requirements
     
  18. Steve-o

    Steve-o

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    Mar 18, 2016
    Hey it's me again. Hope you had a good Easter. I'm having a problem with the output of my sensor. The motor doesn't move when I hook it up, fromm the output of the sensor. Maybe I'm just thinking differently? I used black since white did not give me any output at all.
    http://imgur.com/AWF8BIR
     
  19. Gryd3

    Gryd3

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    Jun 25, 2014
    I don't know what that picture represents, is there more info than just that page?
    (I get an idea.. but not enough to work with)
     
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