12vac to 12vdc

Discussion in 'The Projects Forum' started by jerrymyersmills, May 26, 2011.

  1. jerrymyersmills

    jerrymyersmills Thread Starter New Member

    Mar 22, 2011
    Dear friends
    i have bought a 12VDC relay for project work.The line voltage is 220VAC so i bought a 12V transformer to convert the 22ov into 12V for smooth operation of the relay but i keep hearing this BUZZING sound anytime the relay is working.
    Folks i am a bit confused.
    I suspect that the transformer is supplying 12 VAC to the relay instead of 12VDC.I want to convert 12vac into 12VDC and need some assistance to be able to achieve this.
  2. SgtWookie

    SgtWookie Expert

    Jul 17, 2007
    In the vast midwest of the USA; CST
    Your DC relay may have a diode across its' coil. That would short out the transformers' output for 1/2 of the cycle.

    You can get a small full-wave bridge rectifier from your local Radio Shack store for around $1.39+tax.

    It has four leads; two are AC (indicated by ~) and the other two leads are DC, marked + and -. You just connect it up. If the relay still buzzes, you may need to add a filter capacitor across the bridge output. This would probably do the trick:
    http://www.radioshack.com/product/i...Name=Type&filterValue=Electrolytic capacitors
  3. madhusudan.pigeonsembs

    madhusudan.pigeonsembs New Member

    Mar 17, 2011
    You can follow this attachment.......
    I think you will be very much clear......

    Attached Files:

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