Electronic switch

Discussion in 'General Electronics Chat' started by Dritech, Feb 7, 2012.

  1. Dritech

    Thread Starter Well-Known Member

    Sep 21, 2011
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    Hi all,

    Is there a kind of relay that is latching but without it being supplied continually? (i.e. when supply is given, contact is close. If supply is removed, contact remains closed. When the supply is applied again, the contact will open).

    The reason why i want it this way is because i want the system to be low in power consumption as much as possible.
     
  2. crutschow

    Expert

    Mar 14, 2008
    13,000
    3,229
    Yes, Google "latching relays".
     
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  3. Dritech

    Thread Starter Well-Known Member

    Sep 21, 2011
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    5
    But all lutching relays need continuous supply to their input pins to keep the contacts close. Am i right?
     
  4. scottyjr

    New Member

    Aug 12, 2011
    12
    4
    No, the latching is mechanical. Another application of voltage to the coil will unlatch it, opening the conatcts. - Scotty
     
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  5. Dritech

    Thread Starter Well-Known Member

    Sep 21, 2011
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    Ok, didn't know that. Thanks.
     
  6. wmodavis

    Well-Known Member

    Oct 23, 2010
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  7. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    Don't forget that the "holding current" for a regular relay is typically much less than the pull-in current. Meaning that with a regular relay you can really reduce its power consumption by a method to reduce the current level after the relay has been operated.
    Of course its not like a latching relay in that no current is required to keep its state..But you might also have issues with a latching relay in situations where you must ensure its in the correct state after a power loss situation.
     
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  8. Dritech

    Thread Starter Well-Known Member

    Sep 21, 2011
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    Thanks for the information mcgyvr. I may consider connecting an LCD with one of the contacts to indicate the state of the relay.
     
  9. Dritech

    Thread Starter Well-Known Member

    Sep 21, 2011
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  10. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    Sure.. but you could also just have the backlight turn off after x amonut of seconds of inactivity. (assuming you have buttons or something to signal a user is actively using it)
     
  11. Dritech

    Thread Starter Well-Known Member

    Sep 21, 2011
    756
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    Hi all,

    Regarding the latching relay that i was going to use to reduce power consumption, is it better to use a solid state relay?? Does solid state relays consumes high power ??

    Thanks in advance
     
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