Relay Question

Discussion in 'The Projects Forum' started by libra, Mar 1, 2013.

  1. libra

    Thread Starter Member

    Jul 27, 2012
    62
    0
    Hi,

    I have buy the relay for the purpose to switch the LED ON when their is not electricity and LED OFF when electricity is present. so i connect the relay with the transformer 9VAC the relay is produce the noise sound then i turn off the AC.

    At relay it was written that it work on 250VAC.

    I also connect the relay with 9V battery but no sound is produced by the relay.


    Here is the link from which you can see the relay which i Buy http://www.ebay.com/itm/100pcs-5V-DC-SONGLE-Power-Relay-SRD-5VDC-SL-C-PCB-Type-/250778760511?pt=LH_DefaultDomain_0&hash=item3a6394353f
     
  2. edwardholmes91

    Member

    Feb 25, 2013
    185
    19
    The reason the relay is making a buzzing sound is because you are using AC. There is nothing wrong with that... although you will hear a sound as the relay de-energises momentarily 50/60 times a second. It's called relay chatter... there is a circuit to minimise it but I don't know it sorry.
     
  3. tracecom

    AAC Fanatic!

    Apr 16, 2010
    3,871
    1,394
    The relay coil you linked to is designed for 5 VDC to operate. If you use 9 VDC, you may burn out the coil.

    It is the contacts which are rated for 250 VAC, not the coil.
     
  4. edwardholmes91

    Member

    Feb 25, 2013
    185
    19
    Sorry, my mistake, I didn't even think to look at the link :rolleyes: If it states in the specification that you can operate the coil on either AC or DC... then that might be why you are getting the chatter effect.
     
  5. libra

    Thread Starter Member

    Jul 27, 2012
    62
    0
    I gave the coil 9VAC then it produced the buzzing sound. Not on 9VDC.

    Did i contact it 220VAC/50HZ? Because i buy it for that purpose. The purpose is that when the AC is not available the LED will turn ON and OFF when AC power is available and battery start charging.
     
  6. tracecom

    AAC Fanatic!

    Apr 16, 2010
    3,871
    1,394
    No, if you connect the coil of a 5 VDC relay to 220 VAC, you will immediately destroy the coil, and the relay will be ruined. It may catch on fire.
     
  7. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,771
    971
    You need a relay with a "Coil Voltage" rating of 220VAC. You connect your "electricity" to the "coil" and your LED is switched with the relays "contacts"

    And please be safe..frankly this is really something you shouldn't be doing as you are exposing yourself to shock hazards/death playing with your AC "electricity".. AC is NOT for beginners.
     
  8. tubeguy

    Well-Known Member

    Nov 3, 2012
    1,157
    197
    Where are you getting 9 volts AC when the power is off ?
     
  9. libra

    Thread Starter Member

    Jul 27, 2012
    62
    0
    I am getting 9 volt AC from transformer. I will not operate the relay on 220 volt ac. i use transformer of 6 volt ac, then connect it with bridge and then relay. In that i thing i put in safe way or not?
     
  10. crutschow

    Expert

    Mar 14, 2008
    13,039
    3,243
    MY reading of the spec says the coil is rated for 3-48V DC (although I'd be surprised if it will actually that high a voltage) . The contacts are rated for AC but not the coil.

    Operating the coil from the transformer is safe but you will need to rectify (and perhaps filter) the voltage.
     
    thatoneguy likes this.
  11. #12

    Expert

    Nov 30, 2010
    16,337
    6,820
    I'm seeing 5V, DC only, 75ma to 90 ma by reading the label on the relay. As far as the Chingrish description, all bets are off. Maybe this drawing will give ideas.
     
  12. libra

    Thread Starter Member

    Jul 27, 2012
    62
    0
    Thank you for the drawing. It will help me alot. I also making this drawing but i do not put the zener-diode in it.
     
  13. libra

    Thread Starter Member

    Jul 27, 2012
    62
    0
    Yes after rectify and filter then to relay. As suggested by #12.
     
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