DIY the latching reed switch

Discussion in 'The Projects Forum' started by hilologic, Jan 9, 2017.

  1. hilologic

    Thread Starter New Member

    Oct 27, 2016
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    Hello,
    I want to made a latching reed switch, but many time I tried the result not consistence. I do not have the tutorial.
    Please share how to made latching reed switch.
    regards

    sony
     
  2. Colin55

    Member

    Aug 27, 2015
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    Show photos of what you have done
     
  3. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Can you post a schematic ?
     
  4. hilologic

    Thread Starter New Member

    Oct 27, 2016
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    Thank,
    I follow the picture from reed switch manufacturer.
    setting latching.png test_Latch.jpg
    after I test it is very difficult make latching position.
     
  5. AnalogKid

    AAC Fanatic!

    Aug 1, 2013
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    "Latching reed switch" is very vague. Please describe what it is you want the switch to do.

    ak
     
  6. hilologic

    Thread Starter New Member

    Oct 27, 2016
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  7. DickCappels

    Moderator

    Aug 21, 2008
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    If a suggestion is permitted, find a magnet that will close a reed switch with a coil around it. Position the magneto to just before the point the switch closes.

    When the coil is energized the switch will close (if you have enough turns and amps in the coil). The switch should remain closed after the current is removed. If it does not stay latched then you need to reposition the magnet and try again.

    To unlatch the switch, send a reverse current through the coil for a short period, 0.1 second should be enough. If a reverse current pulse does not cause the switch to "unlatch" you should increase the amps and turns and try again, repositioning the magnet if necessary.
     
  8. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    The reed switch needs an electromagnet coil to operate it. I don't see one in your pic.
     
  9. hilologic

    Thread Starter New Member

    Oct 27, 2016
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    Hello,
    Actually the device is no need a coil, just the magnet polarity to make the latch or unlatch. The small permanent magnet is sticked to reed switch and to operate just give the other magnet to make latch or unlatch.
     
  10. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    So, does the stuck-on magnet keep the reed contacts closed when the other magnet is removed?
    Are you having difficulty keeping them closed or making them open?
     
  11. hilologic

    Thread Starter New Member

    Oct 27, 2016
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    Lets say, the reed in vertically position and then a permanent magnet move passing from top to bottom the contact state is latching ON. Vice versa if a permanent magnet move passing from bottom to top the contact state is keep OFF. The example application used for level control, the switch condition still run even though have power failure.
     
  12. Jesse Williams

    New Member

    Mar 17, 2017
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    I'm interested in this as well, as I'm trying to make something similar (the few I've found commercially available are pricey). I agree that a coil isn't needed. The concept of a bistable reed switch is that when it is closed (say via N magnetic field), it stays closed until it encounters a S magnetic field, after which is stays open until it again encounters a N magnetic field.

    @hilologic - I think part of the issue in what you have in your image is that the magnet is immediately on the switch, so I assume that it probably stays in whatever position the magnetic field gives it naturally.

    There are some good details starting on page 3 of this document: https://standexelectronics.com/wp-content/uploads/ReedSwitchNoOrLowPowerSolution-0209.pdf

    This appears to be a latching (Form E) switch:

    http://www.mouser.com/ProductDetail/Standex-Electronics/KSK-1E66-1-BV14501/
     
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