latching solenoid driver circuit design help needed

Discussion in 'The Projects Forum' started by minkey01, Dec 20, 2014.

  1. minkey01

    Thread Starter Member

    Jul 23, 2014
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    Hi. I am replacing an old solenoid with a new latching pull solenoid, and need help designing a circuit for it.

    A latching solenoid works this way : You send a short pulse of power to energize the coil of the solenoid. It pulls in and then power is removed. A permanent magnet then holds the solenoid plunger in for an indefinite amount of time without any power applied. The solenoid is then turned off by sending a second pulse of power, but opposite (-) voltage.

    Ideally I would like a button that when first hit it activates the solenoid and then the next time you hit it, deactivates and so on repeat. It should not keep sending power if someone decides to hold the button down. The specs say 1 sec max on time. I think the coil would overheat and possibly melt. So that would be bad. Nothing is listed in the specs for nominal on time, but I'm assuming something in the range of millisec pulse would be ideal? I'm not sure.

    The circuit should also have the safety components. I have read that solenoids need diodes and caps possibly?

    Ledex Magnetic Latching Box Frame Solenoid B14HD-L-256-B-6
    27.9VDC @ 10% duty cycle in order to get the max force. I was told that duty cycle spec is the electric power duty in order to lower the amps. It is not the mechanical on/off duty time of the solenoid moves.

    Attached is the spec sheet.

    I'm not opposed to buying a pre-made driver if anyone has a link. Otherwise I will continue with trying to find and design a circuit.

    Sorry for the long post, but I wanted to make sure you have all the info. Anyone able to come up with a good circuit design?

    Thank you for the help.
     
  2. antonv

    Member

    Nov 27, 2012
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    You could use some logic gates, a one-shot or two, some pulse-shaping networks and driver transistors
    or
    you could use a small (8-pin) micro controller and driver transistors.

    Which sounds more appealing?
     
  3. MikeML

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    Oct 2, 2009
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    Start with version 3 or version 4 on this page.

    Add a DPDT relay (or use a relay with additional contacts as part of the flip-flop) to reverse the polarity through the latching solenoid.

    Use the momentary push-button (the same one that is toggling the flip-flop) to define the duration of how long the latching solenoid is pulsed.
     
    Last edited: Dec 20, 2014
  4. Papabravo

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    Feb 24, 2006
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  5. MikeML

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    That is just a set-reset relay latch. TS needs a relay toggle flip-flop.
     
  6. MaxHeadRoom

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    Jul 18, 2013
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    You cannot connect a BEMF diode across these coils due to the polarity reversal to disengage.
    Max.
     
  7. MikeML

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    Sure you can. You just put it outside of the relay H-bridge.
     
  8. MaxHeadRoom

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    So far there has been no mention of H bridge or electronic switching?;)
    Max.
     
  9. Papabravo

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    Feb 24, 2006
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    That was less than clear from the first paragraph in the original post. I see where the clarification was in the second paragraph.
    Many controls are done that way to prevent ambiguity about the present state by having separate switches for on and off.
     
    Last edited: Dec 21, 2014
  10. minkey01

    Thread Starter Member

    Jul 23, 2014
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    thank you all for the advice.

    so maybe something like this would work :

    http://www.seeedstudio.com/depot/L298-Dual-HBridge-Motor-Driver-p-284.html

    there are plenty different models of these h bridge solenoid drivers available. none specifically for a latching solenoid though. i wonder if they would mind doing just the short pulses to activate and deactivate.

    making the logic circuit with the button should be do-able. and then just use one of these products with it.

    thoughts?
     
  11. MaxHeadRoom

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    How about a P.B. relay version?
    I could show a possible one later today?
    It is not clear what the coil voltage is?
    Max.
     
  12. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    I think you'll need tens, if not hundreds of mS, depending on what you are using the solenoid for. The inertia of the mechanical load will be key.
    The coil current needed will depend on pull force. The maximum allowed current depends on duty cycle of use.
    How much force do you need at what stroke?
    How often will the button be pushed?
    Could you use a simple change-over switch instead of the button?
     
    Last edited: Dec 21, 2014
  13. MikeML

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    Second sentence, post #3.
     
  14. strantor

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    Is your solenoid large enough to mount a couple of microswitch limit switches on it?
    [​IMG]

    If so, all you would need is a couple of diodes.
    [​IMG]
    this is the circuit used for motorized linear actuators. It cuts power in one polarity when the actuator (solenoid in your case) reaches full stroke in one direction, but allows power applied in the opposite polarity until it reaches full stroke in the opposite direction. Does not require any fancy timer circuits, and allows the actuator exactly the correct amount of time to fully stroke, even if that time span has a variation in it (due to load changes, temp changes, battery voltage sag, etc.)
     
  15. MaxHeadRoom

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    Link does not work, my antivirus shows it as Malware when clicked on.
    No flip flops, just relays with built in pulse.
    Max.
     
  16. MikeML

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    Here is what that link opens to: (no malware that my checker detects). Anybody else have a problem with this site?

    rel.jpg
     
  17. strantor

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    Kaspersky sure doesn't approve of it. I chose Kaspersky's option show me the page but block the malicious content, and apparently every graphic on the page is part of a malicious content database but not the page text.
    kasp1.png kasp2.png kasp3.png
     
  18. minkey01

    Thread Starter Member

    Jul 23, 2014
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    Hello again.

    Found something that is almost perfect! They are called pick and drop modules.

    http://www.oesincorp.com/pick-and-drop-module.htm

    I would still need the power to be 10% duty cycle. The features do say : "Microcomputer Based, May Be Re-programmed for Your Application" and "Pulse Width Modulated (PWM)". So this sounds promising. I'll call them tomorrow and see if they can set it up for 10%.

    The last issue I see is still getting the output to flip flop back and forth from +VDC and -VDC. The activate and deactivate. Maybe some sort of logic circuit could be used with this module and I will be all set.

    Seems like it's getting closer to a solution.

    Happy Holidays!
     
  19. MaxHeadRoom

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    Jul 18, 2013
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    You need a controlled pulse, and once the armature has shifted that action is disabled, same for release direction.
    If you go with that module, you will also require the polarity reversal.
    What is the mean voltage rating of the one you have?
    Max.
     
  20. minkey01

    Thread Starter Member

    Jul 23, 2014
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    planning on ordering the solenoid that uses 27.9 VDC (Nom) 10% duty

    yes, trying to figure out the polarity reversal with that PDD-01 module.
     
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