Noise in transformer.

Discussion in 'General Electronics Chat' started by RRITESH KAKKAR, Feb 17, 2011.

  1. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
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    Hi, on searching circuit in Google, i got this schematic in which capacitor & resistance are connected in series with transformer input.

    how it cancel noise??:confused:
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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    If there is current flowing through the transformer primary when the switch is turned off, a large voltage "spike" will result. The resistor and capacitor in series across the switch act as a "snubber" to limit the amplitude of the initial spike, and to cause subsequent oscillations to quickly decay.
     
  3. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
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    But, how to find there values??
     
  4. SgtWookie

    Expert

    Jul 17, 2007
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  5. nomurphy

    AAC Fanatic!

    Aug 8, 2005
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    Provided the switch is a standard SPST mechanical switch as shown, then this snubber application has nothing to do with noise prevention. However, the snubber does help to prevent the switch from internally arcing whenever it is opened or closed which helps keep the contacts in good condition.

    When snubbers are used across dynamic switches, such as transistors, then they help to reduce repetitive switching noise.
     
    Last edited: Feb 23, 2011
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  6. BillB3857

    Senior Member

    Feb 28, 2009
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    Noise can be audible or electrical (Radio interference). Snubbers work on the electrical noise.
     
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  7. mkbutan

    Senior Member

    Sep 30, 2008
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    Sir if i am not wrong the audible sound/NOISE produce if the winding is not good (having AIR GAPS) or there is vibration in bobbin frame ie.- I,E's of the transformers

    Noise can be audible or electrical (Radio interference). Snubbers work on the electrical noise.
    written by bill he is right
    the electrical noise can be reduce by good combination of L,C,R CKT with diode
     
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