model elevator

Discussion in 'General Electronics Chat' started by tznuk, Nov 29, 2007.

  1. tznuk

    Thread Starter New Member

    Nov 29, 2007
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    I am making a toy parking garage for my daughter and i want to put in a motor controlled elevator that can stop on any one of the three floors. I know nothing about electronics or anything and I am trying to have this finished for Christmas. Please your help is needed. I would like to run this system off of a 9v battery.
     
  2. thingmaker3

    Retired Moderator

    May 16, 2005
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    That is just too cute!:D

    You'll need some kind of sensor for each floor. A microswitch is one good choice. You'll need a motor, of course. Also three buttons for your daughter to push. And some logic circuitry. (That last part is less intimidating than it sounds.)

    Do you have access to a parts source? Radio Shack would work a as a last-ditch, but a real parts supplier near you would be better. A Fry's or Norvac or some such? Maybee a surplus parts dealer?

    I'll throw together a schematic over the weekend. (Although I suspect someone here will make a better one sooner.)
     
  3. tznuk

    Thread Starter New Member

    Nov 29, 2007
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    Is there any way to make it where there is just an up/down switch/lever and it would just automatically stop at all three floors?
     
  4. thingmaker3

    Retired Moderator

    May 16, 2005
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    Yes. Would be even easier. We could use something called a "latching circuit." Pushing "up" or "down" would latch the motor moving in the correct direction. The sensor on the next floor would open the latch and stop the elevator.

    Two pushbuttons. Two relays. One DC motor. Three microswitches.
     
  5. thingmaker3

    Retired Moderator

    May 16, 2005
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    This is just too much fun!:D:D:D
    toyelevator.jpg

    Okay, all you Santa's helpers in the peanut gallery... where are my errors, what improvements are there? Let's get this thing ready to load onto the sleigh!!
     
  6. Voltboy

    Active Member

    Jan 10, 2007
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    If it's at third floor, the 3 floor witch will be open and if you press the down button it wont go down.
    Probably I'm wrong but just saying in case I'm right. :rolleyes:
     
  7. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
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    Good catch, Yoda!

    toyelevator2.jpg

    I also see the "down" will not latch direction. Elevator will go down while button is pressed, but will go up when button is released...

    Needs more work...
     
  8. cumesoftware

    Senior Member

    Apr 27, 2007
    1,330
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    This really needs more work. You should use relay interlock and the UP or DOWN button will activate the relay even at the top/bottom floor. The elevator will continue to run to the very top/bottom of the shaft.

    Also, more strange is the fact that the circuit is not symmetrical. I expect the conditions on the top floor to be different of those on the bottom floor.
     
  9. recca02

    Senior Member

    Apr 2, 2007
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    in that case, any suggestions?:rolleyes:
     
  10. cumesoftware

    Senior Member

    Apr 27, 2007
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    Sorry. You caught be in the middle of posting something. Tomorrow I'll draw and post a possible solution.
     
  11. thingmaker3

    Retired Moderator

    May 16, 2005
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    Excellent observations, both of them.

    Another revision:
    toyelevator3.jpg
    Note the second micro-swich on the middle level. Does anyone make double-pole micro-switches?
     
  12. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
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    In one of those ironies of life, I decided to post up the logic for a working three level elevator I designed. This was right after I replied to a post about a bad PSU. My other PC which is running W98 to support my very old CAD program now has also got a failed PSU.

    No, microswitches are all single pole. You can mount two together to make them work as a double-pole switch, but synchronizing them can be a challenge. The kludge is to use a single microswitch to operate a DPDT relay.
     
  13. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    With all of the relays and motor in use, I suggest you consider using a "wall wart" type power supply, as otherwise you're going to very quickly go broke buying batteries! :eek:

    Using CMOS logic IC's would help quite a bit in conserving power, as well as being very cheap to experiment with.

    Motors don't stop on a dime; the rotors have inertia, and once turning they'll tend to keep on turning. In order to stop them more quickly, you'll need some kind of braking mechanism or circuit; otherwise the elevator car will consistantly overshoot the destination floor.

    Real elevators have a sensor to indicate when the car is approaching a floor; the motor is gradually slowed down and then "creeps" towards the point where the elevator floor matches level with the current floor. It might be easier to use optics than microswitches for this.
     
  14. recca02

    Senior Member

    Apr 2, 2007
    1,211
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    :rolleyes:
    this is getting a little too complex for Santa(from my standpoint).
    NE ideas to make it simpler.
     
  15. cumesoftware

    Senior Member

    Apr 27, 2007
    1,330
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    Here it is what I've done. I'm using contactor symbols in this ladder diagram, as it is normal in industrial diagrams.
    lift.jpg

    You can use two relays instead of four, if you can find those four contact relays (quad pole, double trow).

    This is not a perfect solution, as you will need to find a double pole normally closed contact as a sensor for your middle floor. The alternative is to use an extra relay. If you need more middle switches, you can add more switches in series with that one. If you are using the extra relay option, you don't need to add more relays.

    This circuit has interlocks for both directions. It is impossible to activate both directions at the same time.

    Notes:
    N.O. - Normally open contact;
    N.C. - Normally closed contact;
    Sensors are drawn as limit switches.
     
  16. tznuk

    Thread Starter New Member

    Nov 29, 2007
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    :confused: I know everything you guys are saying makes sense to yourselves, but i really need it explained so that a child could do it. Because I know NOTHING about how to build this thing or even how to interpret the drawings. What i was hoping for/thinking (don't know if it works) that maybe there would be like a lever or two buttons on the same thing that would have an up and down. From that it would control whether it moved up or down and stop at each floor. There are no doors to open, just up down and stop. I would also like this all to run off of a 9V battery. let me know any suggestions.
     
  17. cumesoftware

    Senior Member

    Apr 27, 2007
    1,330
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    Although I understand your point, you should make an effort. It is rather difficult to "express" circuits without using diagrams.

    As so, I advice you to do some research on "Ladder logic". Start by wikipedia:
    http://en.wikipedia.org/wiki/Ladder_logic

    Keep in mind that is very difficult to assemble such circuit without the use of a diagram as a guide (for example, just using speech, as in "connect A to B"). So, you are really required to interpret the drawings. But interpreting them is not that difficult. You can learn how if you make an effort, just like we are doing by helping you (don't get me wrong). In other words, effort must come from both sides.

    I can assure you so far that nothing complex was suggested (except perhaps the idea of slowing down the lift). The circuits so far are in response to your requirements (no doors, just a simple three stop lift with two buttons). The interlocking I suggested is to avoid short circuiting by pressing both buttons at the same time. This is especially dangerous when batteries are involved, as they can explode.
     
  18. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
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    Once we have a consensus on a workable plan, I'm sure we can translate it from nerd-speak into English.;)

    Sgt Wookie is right about the relays. At 200mA a pop, they'll suck a battery dry in short order.

    An easy fix for motor inertia in such a tiny motor would be to simply gear it down. Perhaps a screw could be used to raise and lower the elevator platform.

    Tznuk, is this for HotWheels/Matchbox scale, or something larger?
     
  19. Voltboy

    Active Member

    Jan 10, 2007
    197
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    Guys. Why don't we use IR LED and a IR diode instead of the microswitch, I think its better idea.
     
  20. tznuk

    Thread Starter New Member

    Nov 29, 2007
    7
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    matchbox, total height 16" elevator car height 3"?
     
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