Electric curtain project: single Push button design

Discussion in 'Circuit Help' started by Ritesh Narayan, Jan 9, 2017.

  1. Ritesh Narayan

    Ritesh Narayan

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    Hi All,

    I am working on a electric curtain or electric blind project at home and I am a bit stuck.

    I would like the curtain to operate a 12V motor drive with a single Push Button switch (not a toggle switch)

    I would like it to behave as follows:

    1st press: forward
    2nd press: stop
    3rd press: reverse
    4th press: stop
    THEN START CYCLE AGAIN

    Of course if it is at one limit then their will be only one direction to go.

    I have done a partial design in the below diagram (shown in driving forward state), but it doesn't work exactly as I want it to:
    I have a limit switch [L] mechanically built in to the motor drive, that is toggled every time the curtain reaches either extreme.

    This is where the design has a problem:
    At the moment, I have a normally open push button switch [C] to control the curtain drive.
    This allows the drive to move forward.
    I have another normally closed push button switch [O] which will stop the drive at any point.
    In this design, the curtain can only be reversed once it reaches the closed limit, where the limit switch [L] is toggled.
    At this point push button switch [O] needs to be pushed (sort of a reset) and then push button [C] will again allow the drive to commence in the reverse direction.
    Again, once reversed to the limit, push button switch [O] needs to be pressed before [C] will allow for forward drive again.

    I would like switch [O] and [C] to be replaced with a single push button to allow it to behave as described initially.
    Also I as below I would like to keep the circuit as simplistic as possible, hence the use of the relays in my first design.

    Your guidance is much appreciated.
     

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    Last edited: Jan 9, 2017
    Ritesh Narayan, Jan 9, 2017
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  2. Ritesh Narayan

    Ritesh Narayan

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    Sorry above post attachment was my first design with single pole relays.
    This has now been updated to Double Pole relays, so below is the correct design I am referencing:

    upload_2017-1-10_0-40-17.png
     
    Ritesh Narayan, Jan 9, 2017
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  3. Ritesh Narayan

    AnalogKid VIP Member

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    Is your project limited to all relays and wires, or can you work with IC's, transistors, etc?

    ak
     
    AnalogKid, Jan 9, 2017
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  4. Ritesh Narayan

    Ritesh Narayan

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    I don't mind using IC's or transistors. I was just trying to keep the design as simple as I could :)
     
    Ritesh Narayan, Jan 9, 2017
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  5. Ritesh Narayan

    AnalogKid VIP Member

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    Is this the complete logic tree:

    1st press: forward
    2nd press or end of travel switch: stop
    3rd press: reverse
    4th press or end of travel switch: stop
    repeat

    If so, this can be done with two latching relays. Relay 1 is DPDT, forward/reverse. DC comes in, goes directly to the coil, and then to the contacts for standard forward/reverse crossover connections. In this way, every time power comes on the direction changes. It gets its power from the relay 2, start/stop. The pushbutton and both limit switches are all in parallel. Closing any of them toggles the power relay.

    This also can be done with a flip flop circuit, either discrete or a chip, followed by a full bridge driver (again, discrete or chip) rated to handle the motor.

    ak
     

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    AnalogKid, Jan 9, 2017
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  6. Ritesh Narayan

    eetech00

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    Hi

    Here's a design that uses a couple of chips...a CD4017B and CD4001B.
     

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    eetech00, Jan 15, 2017 at 8:09 PM
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  7. Ritesh Narayan

    davenn Moderator

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    where's the design ?
     
    davenn, Jan 15, 2017 at 8:18 PM
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  8. Ritesh Narayan

    eetech00

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    oops...just posted it....
     
    eetech00, Jan 15, 2017 at 8:22 PM
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  9. Ritesh Narayan

    AnalogKid VIP Member

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    I don't see the limit switches in there.

    ak
     
    AnalogKid, Jan 15, 2017 at 9:34 PM
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  10. Ritesh Narayan

    eetech00

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    Hello
    Here is a version updated with the limit switch.
     

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    eetech00, Jan 16, 2017 at 1:21 AM
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  11. Ritesh Narayan

    eetech00

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    Ok...here is final corrected version that includes limit switch simulation control.
    The simulation assumes an arbitrary value of 4 seconds for motor to compete movement from start position to end positino. The simulation shows effect of pressing the button before movement reaches end position, in which case movement will only be reverse.

    eT
     

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    eetech00, Jan 16, 2017 at 5:49 PM
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  12. Ritesh Narayan

    AnalogKid VIP Member

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    My fantastic 2-relay solution ran into a glitch, in that the limit switches are not momentary. When the traveler hits one, it changes state and sits there. So it needs to be differentiated before it is combined with the pushbutton, and that is a biiiig cap for 533 mA, greater than 10,000 uF at 25 V. But there are ways around this.

    Are the limit switches SPST or SPDT?

    ak
     
    AnalogKid, Jan 16, 2017 at 6:23 PM
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