[HELP] Optocoupler to solenoid ctrl

Discussion in 'The Projects Forum' started by rafaelluizmesquita, Sep 25, 2013.

  1. rafaelluizmesquita

    Thread Starter Member

    Aug 8, 2013
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    Hello everybody...

    I'm trying to put together a circuit to control a 24V solenoid with a 5V pulse. So the best idea someone gave me was to use a optocoupler in a way it is described in the attachment.

    The thing is I don't know exactly which optocoupler to use. The optocoupler that I am using right now is this one : (http://www.vishay.com/docs/83725/4n25.pdf)

    So the solenoid wont open, because there is not enough current to do it, and if I add some more current up the optocoupler seems to burn.

    I don't know what to do, can someone help me out? I have to deliver something by the end of next week, and I seriously don't know what to do.

    Thanks
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    You should be able to go to 150Ω for the diode emitter, the max is 60ma.
    Max.
     
  3. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    What is the current draw (or coil resistance) of your solenoid?
     
  4. rafaelluizmesquita

    Thread Starter Member

    Aug 8, 2013
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    I think I might have done something wrong when I put it together. Can you show me where I should put the terminals of the solenoid Max?

    Thank you.
     
  5. rafaelluizmesquita

    Thread Starter Member

    Aug 8, 2013
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  6. MaxHeadRoom

    Expert

    Jul 18, 2013
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    That appears to be a Pulsed solenoid?
    I have used these in the past and they require a pulse reversal to engage/disengage.
    Your circuit is basically correct for a normal single acting solenoid, but if the pulsed type, it needs an H bridge or similar.
    Max.
     
  7. rafaelluizmesquita

    Thread Starter Member

    Aug 8, 2013
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    Can you show me how to do it Max? I have no idea how to... This solenoid is a pull solenoid, is it a single acting?
     
  8. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    ?? Looks from its datasheet to be a normal solenoid, albeit for intermittent use not continuous.
     
  9. MaxHeadRoom

    Expert

    Jul 18, 2013
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    It is called a magnetic latching type, or latch/unlatch with opposite polarity pulses.
    I should have a schematic somewhere I can pull up, as i had to design one for a recent customer.
    The alternative is to just use a simple single acting solenoid?
    These are often used in mobile situations where continuous current can drain the battery source.
    Max.
     
  10. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    ?? Can't see anything in the L90-series datasheet to suggest it's a latching type.

    BTW that 4N25 opto should be fine. Make sure you've got it 'right way round' with pins 3 and 6 unconnected to anything.
     
  11. Papabravo

    Expert

    Feb 24, 2006
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    Are your power supplies +24VDC and GND?
    OR
    +24VDC and -24VDC which seems to be what your drawing is labeled.
     
  12. MaxHeadRoom

    Expert

    Jul 18, 2013
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    From Pontiac site.
    L-90 Series
    Chassis Mount Open Frame (Pull) Type DC Solenoids
    Pontiac Coil Inc
    Continuous and Intermittent Duty Cycles. Pontiac Coil’s range of LATCHING, open frame solenoids are all designed for manufacturability and unsurpassed quality.

    You can keep them energized for less likelyhood of stress drop out, but they need reverse to release.
    It is very easy to test, you just need to dab the terminal with the 24vdc, it will stay shifted if latching type, if it does not operate, reverse the polarity.
    Max.
     
  13. rafaelluizmesquita

    Thread Starter Member

    Aug 8, 2013
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    From that picture I sent, where should I place the terminals of the solenoid?
     
  14. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Your schematic you posted shows the way it is connected, just make sure it is not a latching type first by using just two conductors from the power supply to the solenoid leads and see if it latches in, change polarity if it does not pull in.
    Max.
     
  15. MaxHeadRoom

    Expert

    Jul 18, 2013
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    BTW, If it is a normal non-latching type, you should be able to push the armature in and it will return as soon as you let go, if you hear a click and it stays in and requires some effort to pull it out, it is a latching type.
    Max.
     
  16. rafaelluizmesquita

    Thread Starter Member

    Aug 8, 2013
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    This is not that type of solenoid. Whenever I fire it up, it just pull it. When I take the power off of it, the pin stays inside.
     
  17. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Remove Sol from the circuit and apply 24v manually across the coil (do not use a BEMF diode), when you get it to pull in, if it stays in at this point, reverse the polarity and see what happens.
    We need to find out it it is nature of the device or your circuit.
    If it pulls in and releases when you remove power, then it is your circuit.
    Max.
     
  18. rafaelluizmesquita

    Thread Starter Member

    Aug 8, 2013
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    It doesn't. That's my point. I put it in in the 24V power sup, and it pulls it in. I reversed the polarity and nothing happened.

    In fact if I reverse the polarity will apply force to keep the pin in.
     
  19. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Then it would appear that although it looks like a normal single acting solenoid, the return spring or whatever method is used to return the armature is missing?.
    I see no return method in the data sheet, Pontiac Coil make all types, this could be a PULL type and the application it is used on does the return when power is released?
    Looking at some web resources, it would seem this may be only a pull type, with no return fitted?
    Max.
     
    Last edited: Sep 26, 2013
  20. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    So when you say (post #1) that 'the solenoid won't open' do you mean it won't pull in or it won't return after being pulled in?
     
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