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Fun with solenoids

Discussion in 'General Electronics Discussion' started by RichardAu, Jul 14, 2013.

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  1. RichardAu

    RichardAu

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    0
    Jul 14, 2013
    I am a novice hobbyist and I need your help with solenoids.

    The problem:
    A metal rod that is about 6.3mm in diameter needs to be pulled across 60mm. This metal rod holds about 400 grams of weight.

    Ideally the solenoid will operate from 12VDC (not a car battery though). The solenoid pulls this metal rod while it is charged.
    It will be charged for a long time (hours) till say, I turn off the power or interrupts the solenoid with a pulse.

    How can I build this solenoid? That is, length of copper wire, diameter of the wire, how may turns, length of solenoid, and so forth?

    Many Thanks,
    Richard
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,387
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    Jan 21, 2010
    60mm is a long way for a solenoid.

    What are you actually trying to do? There may be a better way,
     
  3. RichardAu

    RichardAu

    3
    0
    Jul 14, 2013
    I am experimenting with a metal rod that keeps a plastic flap valve closed.
    The metal rod is attached to the plastic flap and has horizontal movement (rather than a vertical movement).
    You can see example of this part in the following link:
    http://www.rainharvesting.com.au/products/tank-essentials/flap-valves
    (part numberTAFV02).

    The flap opens by gravitation so if nothing holds the rod it simply opens.
    When the flap is fully open the metal rod travels 60mm hence I need to pull it back that distance.
    The flap fully opens, I cannot open the flap just say half way and then pull it 30mm instead of 60mm.
    I prefer to have just a solenoid if that is possible so that I do not end up with many different parts.
     
    Last edited: Jul 15, 2013
  4. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    May 8, 2012
    Solenoids aren't that efficient. You might be better advised to look into servo motors.

    Chris
     
  5. RichardAu

    RichardAu

    3
    0
    Jul 14, 2013
    Thank you for this reply.
    It does give me idea to convert rotary motion to reciprocating motion (scotch yoke perhaps). Control the rotary motion by using a servo (for instance).
    OK, if I take this design what 'strength' should the servo be and how would you control its motion?
    What is the issue of a solenoid, why would a solenoid not work here?
     
  6. BobK

    BobK

    7,682
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    Jan 5, 2010
    Look at how a car window actuator works.

    Bob
     
  7. sndscientist

    sndscientist

    47
    1
    Jul 10, 2013
    don't you mean a car door lock actuator?. they have a throw around 6 cm. they are 12 volt motors and they are readily available for next to nothing.
     
  8. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

    4,960
    648
    May 8, 2012
    We're not saying that a solenoid won't work. It's your long stroke requirements that's the issue. If you can find one to fit your needs you may find the current requirements to be more than you expected. You should also be aware that the pull force of solenoids are not
    constant. They have much greater pull force when the piston is fully retracted as opposed to when it's fully extended. We can give you supplier links so you can determine if there's an appropriate model.

    Servos torque specs are fairly constant. They're controlled via pulse width modulation (PWM).

    http://www.servocity.com/html/how_do_servos_work_.html

    Chris
     
  9. BobK

    BobK

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    Jan 5, 2010
    Yes, that would be better.

    bob
     
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