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Discussion in 'Electronic Basics' started by I_Have_No_F*****_Idea, Jul 28, 2003.

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  1. I haven't a clue what to look at so i would like to ask for some advice as
    to the Simplest way I can do this or what it is i should be looking at....



    I would like to construct a very simple on/off electrical switch that is
    activated by a secondary momentary on switch...

    If it isn't clear then maybe this will help if you understand what i am
    going to use it and how....I am tring to construct a LED display for inside
    my house that shows the state of my automated roller door ... the 3 states
    being all the way down, midway, all the way up.

    states 1 and 2 are easy that is all the way down and all the way up. But the
    midway point is proving challenging as i would like to activate the LED
    circuit (very simple on/off electrical switch ) via a reed switch (secondary
    momentary on switch)... so as the door goes up the LED comes on and stays on
    until the door comes down and turns it of....

    Any thoughts?

    thanks
     
  2. 12 volt dc.....
     
  3.  
  4. Rich Grise

    Rich Grise Guest

    Just use the limit switches. When the top limit switch is active (I
    don't know if they're NO or NC), it's up. When the bottom switch
    is active, it's down. When neither is active, it's in the middle
    somewhere.

    Hope This Helps!
    Rich
     
  5. I'm not sure I understand completely. When you say "midway" don't you mean
    not down AND not up. You have a switch that indicates when the door is all
    the way down. Another switch indicates all the way up. These two conditions
    are required for an automatic door opener, and are included in the
    controller box. They are simple leaf switches with adjustable mechanical
    setpoints.

    So, you have two of the three states. The third state is 'midway', which is
    simply NOT UP AND NOT DOW>

    Am I missing something?
     
  6. Thanks Rich for the imput...

    my wife said "what do you want one in the middle for anyway? If you are
    having difficulties with that one then why are you making it difficult for
    yourself?" My reply: " I want to see if I can do it. I want to learn more
    about electronics. And yes I'm a big kid who wants to play."


    :)
     
  7. Thanx The raymond family

    You are right regarding the limit switches in the merlin door opener, but I
    am not confident enough to play around in the guts of the controller unit
    for fear of destroying something, so i have tried to set this up completely
    separate from the merlin door opener.

    The reed switches would be placed on the roller door track, one at the
    bottom, one at the midway point and the third one at the top.

    the 3 LED represnetation would be: none on =door completely closed, one
    light= door partially open, 2 lights= door half open, 3 lights= door
    completely open.

    As i have said the top and the bottom isn't the problem, I have them working
    it is the midway point so forget about the bottom and top.

    At the midway point the reed switch is activated momentarily; as the magnet
    passes on the roller door ; so this then would turn on a separate ciruit
    with the LED..... then when the door closes it is reverse it would turn the
    circuit (LED indicating the midway point) off...???

    I hope that is clearer then mud... I'm sorry but i really am a rank beginner
    when it comes to electronics so i don't know the jargon/ expressions to
    explain this simplier...

    thanks for the imput....
     
  8. Rich Grise

    Rich Grise Guest

    Look up "and gate" on http://www.google.com and see how many different
    ways you can make an and gate. Or an or, nand, or nor. And if you
    really want to get funky, build a few exclusive ors and an adder,
    then it's only a few gazillion iterations from there to supercomputer!

    Cheers!
    Rich
     
  9. Gene

    Gene Guest

    Maybe an idea like I used for something similar to what you are trying to
    do. I mounted one micro switch at top of the track. This controls the full
    open light when the door is all the was to it's limits buy depressing the
    switch lever. For the position of 1/2 open I used a mercury bulb switch
    that I mounted on a tilt platform that is activated by a small nub I mounted
    on the moving door. When the door goes up the nub tilts the mercury bulb
    switch on and when it goes down the nub catches the platform and returns it
    to the rest position. So my setup is just mostly mechanical with 2 lights
    showing for full open, 1 for partially open (1/2), and 0 for closed. In my
    new house I have a TV camera pointing at the front door, driveway and garage
    door so I can monitor those area's. Hope this give you some idea's to solve
    your problem.
     
  10. Good suggestion. Another, simpler idea is to mount a magnet strip along the
    length of the door that you want the midway switch activated. You can buy
    3/4" wide magnet strip with adhesive backing.
     
  11. Gene thanks mate.... worst case scenario i will use a mechanical solution...
    but i prefer the non contact solution so far at the bottom and top using the
    reed switches and as for the middle it may be the solution i need so will
    keep trying to work out the problem using the reed switch/non-contact but
    your idea sounds feasible... ;-)

    thnx
     
  12. the Raymond Family...

    thanks mate... but the roller door in my version of the design has the
    magnet physically mounted on the bottom of the roller door, then this magnet
    activates the reed switches mounted at the points described
    earlier(bottom,midway,top) mounted on the roller door track ( as you
    described puting the magnet at the activation point), so that as i have said
    isn't the problem it has been the electronic switch that allows a on/off
    result from the midway switch....

    thnx mate
     
  13. Rich Grise

    Rich Grise Guest

    Not only do you not need a third switch, but the scenario you describe
    won't give you the indications you're after. When the door is closed,
    the down limit switch is actuated (NO or NC remains to be seen - do you
    know how to operate a voltmeter?) and your "CLOSED" LED is lit. As soon
    as it starts up, the down switch deactivates, the CLOSED LED goes off,
    and you have no lights for awhile - then the magnet passes the "mid"
    switch, and the "IN THE MIDDLE" LED lights briefly, and goes out as
    the door continues to open. At the top, the top limit switch actuates,
    and the "OPEN" light comes on.

    You don't need to add ANYTHING - the switches are already there - all
    you have to do is determine what signal is at them, to decide how
    to condition them properly to drive your logic. There are 4 states:
    UP, DOWN, MOVING, and BROKEN. To get a reasonable "in transit" signal,
    you'd have to line the whole edge of the door with magnets, or do
    some sophisticated "is it moving?" - type detection, but that sounds
    a little on the advanced side.

    Good Luck!
    Rich
     
  14. hi rich

    with the help of everybody and and a close friend i have struck a solution
    that allows everything that i wanted to achieve... thanks again... if anyone
    is interested then i 'll post it on a web page and send the link for it
    here???


    regards and thanks again grrrrrrrrrrrrr
     
  15. John fields

    Mate i was getting to the point that i diddn't think i was writing clearly
    enough, but you just proved to me that i was explaining clearly as what you
    describe about the top and the bottom switch is exactly what i am doing with
    the reed switches. As for the middle you say about "then use a retriggerable
    one-shot to debounce the middle switch and then use the output of the
    one-shot to toggle a "D" type flip-flop. " Pardon my ignorance but I have
    no idea what you are talking about suffice to say that I am using google to
    research those topics. If youwould send the schmatic you spoke about i would
    love to learn from it and probably would change my design to your idea.

    Mate thanks again.
    Grant
     
  16. ~^Johnny^~

    ~^Johnny^~ Guest

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    ~~~~~~~~
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    save all the parts." - Aldo Leopold
    ~~~~~~~~
     
  17. John Fields

    John Fields Guest

     
  18. alec_traun

    alec_traun Guest

    There is a much simpler way to this. If I understand the problem you
    would like to have three indicaters - UP MIDWAY DOWN - for your door.
    You already have the UP and DOWN and just need some way of indicating
    that the door is somewhere inbetween. Simple connect the ouptuts from
    your UP and DOWN switches to a 2-input NOR GATE and the output of the
    gate to the MIDWAY indicator.


    UP --------------- Up LED
    | __
    =)__)o----- Midway LED
    |
    DOWN -------------- Down LED

    Hope this helps
     
  19. John Fields

    John Fields Guest

     
  20. John Fields

    John Fields Guest

    ---
    I think you must have misunderstood the OP's requirements:


    "The reed switches would be placed on the roller door track, one at the
    bottom, one at the midway point and the third one at the top.

    the 3 LED represnetation would be: none on =door completely closed, one
    light= door partially open, 2 lights= door half open, 3 lights= door
    completely open.

    As i have said the top and the bottom isn't the problem, I have them
    working it is the midway point so forget about the bottom and top.

    At the midway point the reed switch is activated momentarily; as the
    magnet passes on the roller door ; so this then would turn on a separate
    ciruit with the LED..... then when the door closes it is reverse it
    would turn the circuit (LED indicating the midway point) off...???"


    Clearly this is what he's looking for:

    DOOR DIRECTION BOTLED MIDLED TOPLED

    FULLY CLOSED OFF OFF OFF

    OPENING, < HALFWAY OPEN ON OFF OFF

    OPENING, AT MIDPOINT ON ON OFF

    FULLY OPEN ON ON ON

    CLOSING, < HALFWAY CLOSED ON ON OFF

    CLOSING, AT MIDPOINT ON OFF OFF

    FULLY CLOSED OFF OFF OFF


    and, clearly, your circuit won't satisfy those criteria.
     
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