Reversible Door on Timer

Discussion in 'The Projects Forum' started by dledge, Feb 11, 2014.

  1. dledge

    Thread Starter Member

    Feb 11, 2014
    60
    1
    I have a DC motor that is currently connected to a circuit that allows for the circuit to be reversed. The motor is connected to a toggle switch that performs two functions:
    1. Breaks the current to the motor
    2. Reverses the direction of the motor

    The operation occurs in the following:
    1. A light switch wall timer is triggered ON
    2. DC motor begins to run in the direction dictated by the switch.
    3. Motor continues to run until the toggle switch is flipped.
    4. The light switch wall timer is triggered OFF
    ...Repeat steps 1-4

    The act of the power to the DC Motor circuit board 'resets' the motor and allows it to again run. The position of the toggle switch determines the direction the motor will run.

    WHAT I NEED:
    The mechanical function of the switch is causing issues as it is not adaquately translating to the desired travel of the door to which the motor is connected. I would like to change out the mechanical switch with an electronic one that would register when the door is in full OPEN or full CLOSED position, send the signal to the motor circuit board to stop movement AND reverse direction of the motor for when the Power cycles via the light switch wall timer.

    WHAT I THINK:
    I believe I need an H bridge chip along with two Reed switches.
    What I cannot figure out, is, how do I maintain the current flow state to the motor while the door is in transition?

    I think this is a simple problem, but it is elluding me.
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,509
    2,369
    On the surface it Doesn't seem to warrant anything electronic?
    It seems a point to point application where simple limits are used.
    There is also an all inclusion solution that would cover the timer and any simple logic, like delays etc, this would be a Smart Relay, made and relabeled by a few manuf. such as Omron, Idec, Siemens etc.
    This is an off the shelf solution that would not require any circuit building, just simple programming, S/W offered is often free or downloadable somewhere.
    Max.
     
  3. inwo

    Well-Known Member

    Nov 7, 2013
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    Can you simplify?

    Push button= door runs open and stops
    Push another button= door runs closed and stops

    Or must both directions be initiated by the same button?

    Or simpler yet.
    Can a toggle be switched one way= door closes and stops.
    Toggled other way= door opens and stops.
     
    Last edited: Feb 11, 2014
  4. inwo

    Well-Known Member

    Nov 7, 2013
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    Just in case the "simpler yet" would work for you.

    DPDT control switch. (electricians 4way)
     
  5. dledge

    Thread Starter Member

    Feb 11, 2014
    60
    1
    Ok...so if I use a limiter switch, how does that signal the motor to stop, and then upon start up, run in the reverse direction?
     
  6. burger2227

    Member

    Feb 3, 2014
    190
    24
    There are switches below the diodes for each direction of current so the switch can only run the motor in the opposite direction. The magnetic reed switches close again once the door has moved back in the other direction enough. Then the switch can be moved in either direction again.
     
  7. inwo

    Well-Known Member

    Nov 7, 2013
    2,433
    315

    The previous is a correct explanation of my circuit.
    I would use standard micoswitches rated for full motor load to keep it simple.

    This circuit has the advantage of the diodes across the limits protecting the switches.

    Disadvantage is that motor coasts to a stop. No dynamic braking.
    No stop function is shown. Every time the switch is thrown, it makes a complete cycle.
    An e-stop is mandatory.

    Also there is no provision for instant motor reverse damage if switch is flipped mid-cycle.

    If this is something, you think might work for you, I can help with details, or modify.

    Did you follow the 4-way switch reference? I've been looking for an excuse to use one for motor reversal. :)
     
    Last edited: Feb 11, 2014
  8. dledge

    Thread Starter Member

    Feb 11, 2014
    60
    1
    I found a thread on latching relays...

    Given that the only part of the system that I want to replace is the toggle switch, could I do this with two limiter switches connected to a latching relay? The idea would be that when the limiter switch is reached, the latching relay changes state which stops the motor and reverses its direction.

    So, two limiter switches (NO) controlling a latching relay. The latching relay determines the direction the motor will run.

    Will this work?
     
  9. dledge

    Thread Starter Member

    Feb 11, 2014
    60
    1
    Sorry...I meant to say..."Pulse Latching Relay".
     
  10. inwo

    Well-Known Member

    Nov 7, 2013
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    The only reason that you would need latching relays is if the initiating switch must be a momentary action (spring return).

    If that is the case I can redraw it.
    You did mention replacing switch.
    Is there an issue with a normal toggle switch?

    Maybe the place to start would be listing the components that you want to use. ie. The type of switch or buttons to start cycle.

    This is what you need with my diagram.

    Battery or power source
    Motor
    2 limit switches
    Toggle switch (not spring return)
    2 diodes
     
  11. inwo

    Well-Known Member

    Nov 7, 2013
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    I don't know why, as I'm still not sure what you want.:)

    Here is a diagram with one button automatic control.
    Uses two 4PDT relays or 4 DPDT relays.

    In case of power outage or door stuck in the middle, close relay must be slow operate, to bias door toward opening on restart.

    I lean toward the previously suggested simple solution!
     
  12. dledge

    Thread Starter Member

    Feb 11, 2014
    60
    1
    I was able to figure out the existing circuit. It consists of an H-Bridge circuit utilizing two Relays. These relays switch upon power on. Power on/off is controlled by the wall light timer.

    So, the timer energizes the circuit, the Relays change state.
    The timer de-energizes the circuit, the Relays maintain state.
    ...rinse and repeat.

    The manual toggle switch was managed by the motor itself, via a control arm that mechanically changed the switch.

    When the toggle switch changed, it broke the circuit and stopped the motor.

    I've attempted to diagram this (see picture). I apologize for the terrible drawing.

    What I need to replace, is the function of the manual toggle switch. The reason for this is that the existing process was not very accurate and I found the travel of the door (duration the motor ran in any one direction), varied over time requiring constant adjustments.

    I'd like to utilize 2 limiter switches (Open, Close) which will trigger a latching relay to change states.
     
  13. inwo

    Well-Known Member

    Nov 7, 2013
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    Possibly, draw what you are thinking.

    I don't see a need for memory other than the limit switches to determine direction.

    Or timers for that matter.:confused:
     
  14. inwo

    Well-Known Member

    Nov 7, 2013
    2,433
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    If you already have the H bridge relays.
    Just connect a maintained toggle switch to them. Put limit switches in series with one of the motor leads as shown in my first diagram. Or in series with the switch leads to H bridge.

    If you must buy more relays, might as well rewire it all.
     
    Last edited: Feb 12, 2014
  15. dledge

    Thread Starter Member

    Feb 11, 2014
    60
    1
    can you get a maintained toggle switch that isn't mechanical? The only ones I see are those that require a switch to be flipped.
     
  16. inwo

    Well-Known Member

    Nov 7, 2013
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    Now you lost me.

    A switch is mechanical.

    Do you want a different method of opening the door? Not a switch.

    Ok, I re-read first post.


    "The operation occurs in the following:
    1. A light switch wall timer is triggered ON
    "

    I'm slow I guess.

    So the door opens automatically at a certain time?

    I was thinking that you used a switch to open the door and a switch to close the door.

    Maybe if you explain how the door is used I can follow.:confused:
     
  17. dledge

    Thread Starter Member

    Feb 11, 2014
    60
    1
    The door in question is a chicken coop door. I bought a motor unit to run the door which included:
    DC motor
    H-Bridge Circuit board
    Toggle Switch

    If you look at the picture, the black round think was an adjustable gear that mechanically flipped the toggle switch after a certain rotation.

    The motor unit was plugged into an outlet that was energized by an off the shelf timer switch (think greenhouse lights). This timer switch would energize the circuit in the morning (door opens), and then de-energize the circuit 10 minutes later. The timer would then energize the circuit in the evening (door closes), and then de-energize the circuit 10 minutes later.

    This works OK, except that the adjustable gear that mechanically flipped the toggle switch would often slip. I tried several other variations on this and have finally decided I need to go completely electronic (ie, no toggle switch).

    So, the motor unit is fine, except for the adjustable gear and toggle switch. I am thinking I could take the three leads from the unit (Common, C_1, C_2), connect this to a dual coil latched relay, which is controlled by two magnetic reed switches located at full open and full closed.
     
  18. inwo

    Well-Known Member

    Nov 7, 2013
    2,433
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    The toggle switch can be replaced by a SPDT relay.

    The coil of which is connected to your timer. 120vac if that is what is output by timer.

    The relay will do exactly what the switch does now, except no off position.

    Motor will turn off when limit is reached in each direction.

    When timer contact is "on" door will be open.
    When timer contact is "off" door will be closed.

    Connect the limit switches in the appropriate leg of the input to H bridge.
    Between relay contacts and H bridge switch inputs.
     
  19. inwo

    Well-Known Member

    Nov 7, 2013
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    Like this................................................
     
  20. dledge

    Thread Starter Member

    Feb 11, 2014
    60
    1
    Thanks for the description and diagram.

    The only concern that I have, is that in order for the H-Bridge circuit to work, it requires a power transition from zero to fully energized. This is why the timer has a full power cycle each time the door is activated.

    Given your diagram, it looks like the motor will only ever run in reverse since the relay and motor both operate on the same power source. I may be mis-reading the diagram.

    This was one of the reasons why I was thinking of the Latching Relay as this would maintain state until the next limiter was hit.
     
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