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Need Help with needed circuit

Discussion in 'General Electronics Discussion' started by worlda, Nov 7, 2012.

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  1. worlda

    worlda

    9
    0
    Nov 7, 2012
    I am using a 12VDC Linear Actuator the Actuator runs by reversing polarity so I want to use one Momentary switch
    push one time to go up and again to go down does anyone have a circuit to do this please help

    Thanks
    charlie
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    You want a push-on, push-off double pole, double throw switch.
     
  3. worlda

    worlda

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    Nov 7, 2012
    help

    thanks but I need to do it with SPST Momentary switch I can not change it its on my auto
    charlie
     
  4. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Nov 28, 2011
    Is this for an electric antenna extender?
    Does the linear actuator automatically stop at its limits?
    I'll try to draw something up.

    PS. How much current does the linear actuator draw?
     
    Last edited: Nov 7, 2012
  5. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Here's an idea. It uses a latching relay to remember the polarity and to provide the voltage inversion. Each time you press the button, it flips to the opposite polarity.

    [​IMG]
    The relay is rated for 8A and its detail page is http://www.digikey.com/product-detail/en/RT424F12/RT424F12-ND/1128677

    The circuit uses four diodes (1N4001 or similar), two 470 ohm resistors, two 330 uF 16V electrolytic capacitors, and one varistor for overvoltage protection.
     

    Attached Files:

  6. davenn

    davenn Moderator

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    Nice one Kris

    added that one to my own collection of ccts :)

    Dave
     
  7. worlda

    worlda

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    Nov 7, 2012
    Thanks it sounds like it will works its for a Linear Actuator it draws 300ma can I use a smaller
    relay? if so which one do you think

    again thanks so much

    Charlie
     
  8. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    What is the initial inrush current of the actuator?

    That is already a small relay, you could certainly locate smaller ones but you are really splitting hairs at the end of the day unless there is a necessity for it to be smaller?
     
  9. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Nov 28, 2011
    Yes, you can use a smaller relay. If your actuator draws 0.3A I would use a relay rated for at least 2A though.

    You should also change the values of the capacitors and the resistors, according to the coil current consumption. The relay I originally suggested draws 50 mA on each coil, and I specified 330 uF capacitors and 470 ohm resistors. You should reduce the capacitors and increase the resistors in proportion to the reduction in coil current. I've marked recommended values below.

    http://www.digikey.com/product-detail/en/V23079B1203B301/PB1085-ND/1633971 (2A contact rating; 11.7 mA coil current) (use 100 uF capacitors and 1.8 kilohm resistors). This is the cheapest option.

    http://www.digikey.com/product-detail/en/DS2E-SL2-DC12V/255-1067-ND/251839 (2A contact rating; 15 mA coil current) (use 100 uF capacitors and 1.5 kilohm resistors).
     
  10. worlda

    worlda

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    Nov 7, 2012
    ok I will lay it out

    Thanks so much for all yout help

    Charlie
     
  11. galaxy

    galaxy

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    Nov 3, 2012
    Good stuff KrisBlueNZ,
    I had a similar requirement not long ago, and spent some time figuring out logic arrays and driver trannys to do the job.
    I could of just used a relay as per your design. But years of "solid state is the only way" made my brain cells ignore the old school electro-mechanical solutions.
    Thanks again, schematic saved for future reference.
     
  12. worlda

    worlda

    9
    0
    Nov 7, 2012
    Hi

    I put it together and it does not work I did see that the Relay is one coil with a center tap with a center is postive when I push the button I get 9.66VDC Than 0VDC I attached a pic of the relay layout this is the one your listed 8amp 12VDC F12-ND/1128677 can you please help

    Thanks much
    Charlie
     

    Attached Files:

  13. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Nov 28, 2011
    Oops! The relay I specified has commoned coils.

    Luckily I can just change the circuit slightly and you won't have to get any new components. Here's the corrected circuit.

    [​IMG]
     

    Attached Files:

  14. worlda

    worlda

    9
    0
    Nov 7, 2012
    Thanks

    I give this a try I also need to make PCB for it do you have any program to lay it out ?


    Thanks so much
    Charlie
     
  15. worlda

    worlda

    9
    0
    Nov 7, 2012
    breadboard it I still can not get it to work can not get the coils to go in and out what do you think


    Charlie


    My error missed a jump works great any help on a PCB for this would be great again thanks for all your help

    charlie
     
    Last edited: Nov 17, 2012
  16. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
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    Nov 28, 2011
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