Non-Latching Relay control

Discussion in 'General Electronics Chat' started by dude521, Apr 21, 2009.

  1. dude521

    Thread Starter Active Member

    Nov 1, 2008
    37
    0
    Hi,

    I have a question about a particular relay I want to get:

    http://www.digchip.com/datasheets/download_datasheet.php?id=336086&part-number=G2R-1A4

    Its a G2R series relay from Omron (I'm looking at the SPST-NO 12VDC).

    In the pin out diagram they never say which side of the coil is positive or negative. Based on what other relays look like, I think that when you apply 12V to pin 5 (and keep pin 1 grounded), the relay will close connecting pin 4 to 3.

    Is this the case or does it not matter?


    Thanks.
     
  2. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
    Coil polarity doesn't matter in this relay.

    ken
     
  3. dude521

    Thread Starter Active Member

    Nov 1, 2008
    37
    0
    Can you explain why? From what I understand, the relay works by passing current through a coil which causes a magnetic field to physically move a piece of metal. If polarity of the coil was reversed, wouldn't the the field push the piece of metal in the opposite direction?

    Thanks.
     
  4. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
    The armature (the moving arm) is made of soft iron. Either polarity of the magnetic field will attract the armature. Either end of a bar magnet will attract iron. If the armature was a magnet, as in single-coil latching relays, it would matter. With two bar magnets, they will attract or repel depending on their N-S polarity. Also, some relays have a built-in flyback diode across the coil. Though they have iron armatures, they also require a specific polarity on the coil because of the diode.

    Ken
     
  5. dude521

    Thread Starter Active Member

    Nov 1, 2008
    37
    0
    Thanks, that was a great explanation.
     
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