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Old 05-26-2011, 09:25 PM
jerrymyersmills jerrymyersmills is offline
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Join Date: Mar 2011
Posts: 29
Default 12vac to 12vdc

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.
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Old 05-26-2011, 09:35 PM
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SgtWookie SgtWookie is offline
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Posts: 22,039

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:
General info:
If you have a question, please start a thread/topic. I do not provide gratis assistance via PM nor E-mail, as that would violate the intent of this Board, which is sharing knowledge ... and deprives you of other knowledgeable input.
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Old 05-27-2011, 04:38 AM
madhusudan.pigeonsembs madhusudan.pigeonsembs is offline
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You can follow this attachment.......
I think you will be very much clear......
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File Type: gif full_wave_rectifier_circuit.gif (11.7 KB, 33 views)
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