Motor Polarity switch With a relay

Discussion in 'The Projects Forum' started by djkasra, May 18, 2009.

  1. djkasra

    Thread Starter Member

    May 17, 2009
    13
    0
    Hi everyone, this is a pretty simple project but i am a new to relays so..

    Diagram here
    [​IMG]

    Goal:
    Reversing polarities on a motor
    (think of a electric car window )

    Situation
    I am buying racing seats for my car and i am planing to keep the electric slider that my original seats had, by re attaching it to the new racing seats. so i have a motor that connects to the track and i need it to go

    forward (when a push button is pressed )
    stop (when the push button is released )
    backward (when another push button is pressed )

    Click Here for A Diagram
    or copy http://i20.photobucket.com/albums/b205/djkasra/MySeatSetup.jpg

    Material
    (2) Push Buttons
    (1) Motor= 12V DC
    (~10) Relay= 12V 30/40A opposite

    Also
    I am trying to make this a Memory seat, so
    see diagram for this section
    cause1:
    putting the key in the ignition

    Reaction1:

    the seat would move forward untill the Forward Triger hits the Forward Stoper.

    cause2:
    Taking the Key out of ignition

    Reaction2:
    the seat would move Backward untill the Back Triger hits the Backward Stoper.


    Helpful Knows
    when Key is in ignition a wire that is known has 12v (other times 0v)
    When Key is out of ignition that same wire has 0v

    Help With:
    i am not sure how i can connect the relay(s) so that when i press

    • Push button one the motor would spin clockwise
    • Push button two the motor would spin counterclockwis
    Also

    • How to use the setup that i have with tigers and stoppers to obtain the memory seat.
    its a simple circuit and just wanted your input, i put a lot of time trying to make a decent diagram so everything is clear.. any help is great, please be very specific using terminals (specially on the relay i am new to the relay world)
     
  2. heavyarms666

    Member

    May 16, 2009
    20
    0
    i cant visualize whats your up to but i believe, you should also buy ic for it.. if u want a 'pres first den forward, press again then backward', then you should have a decade counter for it, 4017 or other ic.. you should also have a transistor to amplify the output of 4017,(4017 alone cant make the relay work)
    you should buy a DPDT relay..
     
  3. djkasra

    Thread Starter Member

    May 17, 2009
    13
    0
    my bad, i guess i wasn't too clear

    imagine a electric car seat that moves back and forth ... thats basicly what i am constructing. as you can see im a novice so i am trying to keep it as simple as i can. (also remember this is for a car) so everything is 12v

    1st Task
    i would have a pushbutton for going forward, and another push button for going backward.[i dont know the name of it, but it be in one unit] both would not be pressed at same time ( imagine a car window button,a switch like that, you can either press it to go up .. or down, but never both)

    2nd Task
    I dont want the motor to have a load on it when it reaches the end of the rail, so i want to put stopers that when the rail is about to end the motor would stop. one stoper for going backwars and one going forward.

    3rd Task
    I also want to make this a memory seat so when one condition is met it will do the tast, and when anopther is met another task is done (these are labled as case1 and reaction1 above

    the reaction will be performed untill the triger hit the stopers in Task2
    the trigers are able to placed almost anywhere in the rail, so when i am comfortable with a position, i would adjust the trigers to that position.
     
  4. djkasra

    Thread Starter Member

    May 17, 2009
    13
    0
    Also, instead of using the stopers and trigers that need to directly touch in order for the motor to stop, what kind of remote led can i use that when ever they lineup on top of each other the motor stopes ? and how simple is it to make? and what other parts are necessary ?

    thank you
     
  5. DonQ

    Active Member

    May 6, 2009
    320
    11
    A couple of notes for you.

    1) There is a notation for relay logic, known as "Ladder Logic", that would probably make your design easier to do.

    It looks something like this:
    Code ( (Unknown Language)):
    1.  
    2. |              Fwd                     |
    3. |   FWD       Limit                Run |
    4. +---[ ]----+---[/]-----------------( )-+
    5. |          |                           |
    6. |          |                           |
    7. |   Run    |                           |
    8. +---[ ]----+                           |
    9. |          |                           |
    10. |          |                           |
    This would engage the "Run" relay coil when the FWD normally open switch is engaged. A contact on that relay would keep it engaged until the normally closed "Fwd Limit" is opened.

    This is only an example. You would have to design Fwd/Rev, and maybe change the Normally Open/Normally Closed depending on your push-buttons and limit switches, but this should get you started.


    2) LED sensors under the seat are probably not what you want to do. They would get blocked by dirt fairly soon. Lookup "Proximity sensor". Again, do not get the LED type. There are magnetic and "Hall effect" types that would operate through dust and dirt. They may be expensive for what you want to do.

    You can make your own magnetic prox sensors by using a "reed switch" and a magnet. Either put the magnet on the sliding part (a magnet doesn't need electric power) and the reed switch on the stationary part or:

    You can put the magnet on the stationary part, opposite the reed switch and far enough away that it doesn't switch (yet). When the metal sliding part gets between them, it will transmit the magnetism across the gap and engage the reed switch.

    3) This is a really easy job for a simple micro-controller.
     
  6. djkasra

    Thread Starter Member

    May 17, 2009
    13
    0
    Thank you soo much, i will look in to the Proximity Sensors for this project but if not i have another idea that will be kind of cool using Proximity Sensors .

    also thank you for the DPDT relay idea for switching polarity
     
  7. heavyarms666

    Member

    May 16, 2009
    20
    0
    now, i know what ur up 2.. before we also made something like that, only a student project so the funds we have are limited.. We use a switch(pushbutton switch, but not like the round one, we use the pushbutton switch that is specially use in a stopper.. i really dont remember how it was called, but you can see it in a old cd rom, it stop the moving part of cd rom from forward or going back)
    but you can use the magnet thing said by DonQ, its easy too..

    in your task 1, you said youll have 2 pushbutton? so there must be latching, we use 555ic for it.. actually, you can use other ic but 555 is what i have and has some advantage..
    http://www.kpsec.freeuk.com/555timer.htm
    here is one site i use before.. see the 555/556 bistable.. it would help.. just put the relay in the output..
    maybe next time, ill post what the schematic we use..
    i hope it works! hehe..
     
  8. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    I suggest that for now, you just keep things simple. That will make it relatively easy to build and troubleshoot in case something goes wrong. It will also help make it reliable.

    Try this schematic; easy enough to build. You'll need some N.O. pushbuttons and N.C. limit switches, and a couple of diodes for the relays.
    [​IMG]

    When S1 is pushed, RLY1's coil is energized, who's N.O. contacts then supplies power to the + terminal of the motor. The motor's - terminal is connected to ground via RLY2's N.C. contacts. When limit switch S3 is depressed, RLY1's coil becomes de-energized; causing the same relay's N.C. contacts to close. This acts as an electrical "brake", causing the motor to stop much more quickly than if power were simply disconnected and the motor left to "freewheel".

    If both S1 and S2 are depressed simultaneously, both RLY1 and RLY2's coils are energized, so power is applied to both sides of the motor. Nothing bad happens; effectively it's the same as if both sides of the motor were grounded.

    One glaring omission is a fuse or circuit breaker. I suggest using one rated around 20A. Make sure you use stranded wire of heavy enough gauge, or else instead of blowing the fuse, the wire will burn up; then you will have a burned-up car.
     
    Last edited: May 18, 2009
  9. djkasra

    Thread Starter Member

    May 17, 2009
    13
    0
    wow, that diagram really helped.. it makes perfect sence to me who is a novice compared to all the other in here.. these stuff are really intresting though.
    thank you soo much this forum is great and from signing up and posting i have gotten my answer. within a short period of time!:D

    (although iam disapointed from ebay sending me the wrong color :mad:seat( jusr got it an hour ago)..lol i asked for tan and i got a gray one.. can i use a transformer to change the color of the seat somehow:eek:?.. lol.. im just kidding thank you all;)
     
  10. djkasra

    Thread Starter Member

    May 17, 2009
    13
    0

    wow, and its tru if both switches were to be pressed at same time nothing would happen,,

    to me this is brilliant great design
     
  11. DonQ

    Active Member

    May 6, 2009
    320
    11
    OK... this "novice" says bye!
     
  12. djkasra

    Thread Starter Member

    May 17, 2009
    13
    0
    .. not u guise, i am talking about my self being a novice
    and i am definitely using your "Proximity sensor" may be not in this situation but in another project that i have in mind , thank you once again for all the inputs
     
  13. djkasra

    Thread Starter Member

    May 17, 2009
    13
    0
    thank you, i read a lot about that, but it is still complicated for my brain lol, but yeh i picked up some sites and tutorials in the counters and all that, thay can all be very useful, very facinationg only i cant apply them as of now.. i need to do a lot more research to become more familiar with them thank you for introducing them.
     
  14. djkasra

    Thread Starter Member

    May 17, 2009
    13
    0

    DIODES

    you said i would need some diodes i found this on ebay is this ok to use?
    here is a table that shoes the specification it says 50v, but that's important not to surpass since im going to be dealing with 12v is this ok to use? and since im buying a bunch can i use them in most of my later projects that deal with working on the car ?
    100 pcs. 1N4001 1A 50V Diode on tape Assortment $3.60
    [​IMG]


    LIMIT SWITCHES

    and i found these for limit switches
    4 pcs Limit Switch NC-NO $6.70
    [​IMG]

    RELAY
    as far as the relays go i got these already
    10pack 12v 30/40amp $24.97
    [​IMG]
     
  15. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Those should all work for you.

    For the S1/S2 pushbuttons, you could instead use a single-pole double-throw center-off switch that's spring-loaded to the center position. Pushbuttons would work just fine though.
     
  16. djkasra

    Thread Starter Member

    May 17, 2009
    13
    0
    ok i will go ahed and buy those then thank you.

    but i have one more scenario that i need to explain later, i have to catch the bus to school since i have no seets in my car as of now..lol, but later on today i will explan the other task
     
  17. djkasra

    Thread Starter Member

    May 17, 2009
    13
    0
    So here is what i came up with(attached) , with your permision, i added the situation to your original design....which i think would work, but i just need your approval.and i think it has one problem

    [​IMG]



    Situation1:Ready to Drive
    when you put the key IN the ignition and turn on one click a wire gets a value +12v that will energize RLY3, and then RLY2 will be activated causing to motor to spin (letsay forward) till the limit switch(S4) is reached. bringing the seat closer to steering wheel

    Situation2:Getting out Of Car
    when you take the key OUT of the ignition OR unturn on one click that same wire gets a value 0V that will de-energize RLY3, and then RLY1 will be activated causing to motor to spin Bokward till the limit switch(S3) is reached. leting the driver to have enough room to get out

    Problem With the addition of My Design :confused:
    it seems that everything will work fine as it is, But lets say after you sit on the chair.. put the key in ignition, the seat will move foward untill it hits the limit switch (S4), (so far soo good)

    now you are driving and feel like bringing the seat back a littlbit , so u hit switch (S1)... nothing happns (the seat wount move back) becouse is as if both switches were presed and RLY1 and RLY2 would both be energized... supling +12V to both terminals of the motor now what ? :confused:
     
  18. djkasra

    Thread Starter Member

    May 17, 2009
    13
    0
    I was wrong, the seat would Move back till S4 is no longer engaged, and then nothing would happen. so the seat would only move may be a milimiter and then both terminals would have the same voltage :confused:
     
  19. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    In my original schematic, the odd-numbered items (S1, S3, RLY1, D1) are for moving in the forward direction, the even-numbered items control movement in the reverse direction.

    As you've already noticed, adding more circuitry to the schematic removes the ability of manual control. You're also going to put a great deal more wear on the motor, running the seat back and fourth every time you start/turn off the engine.

    If you really want to pursue your auto-forward/auto-reverse scheme, it's going to take more logic, which will complicate things significantly. It'll be harder to build, and much more difficult to troubleshoot. You would be best served at the moment by building the original schematic, and getting it working like it should. It will be a good and reasonably simple foundation to build upon.

    I really don't have the time & energy to work up another schematic at the moment; I'm out of town and have quite a few of my own projects in the fire.
     
  20. djkasra

    Thread Starter Member

    May 17, 2009
    13
    0
    ok im definatly going to use your setup and just think harder see what i can comeup with in my free time.

    greathelp, ill post a video link when everything is to show the end result
    thanx again.:cool: and good luck with ur projects too
     
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