Power Supply Board Ripple

Discussion in 'General Electronics Chat' started by Baskaran Manoharan, Apr 20, 2016.

  1. Baskaran Manoharan

    Thread Starter New Member

    Apr 18, 2016
    2
    0
    Hi,
    I am using 19.5V/4.5A power supply, measured the Ripple Voltage across the load It is almost 140mv ,After 10min again i measured Ripple voltage on same load its reduced to 40mV How is it?
     
  2. #12

    Expert

    Nov 30, 2010
    16,284
    6,797
    I would guess that the load current diminished after 10 minutes.
     
  3. wayneh

    Expert

    Sep 9, 2010
    12,122
    3,046
    Putting it another way, the question cannot be answered unless/until the load is known when the ripple measurement is made.
     
  4. AnalogKid

    Distinguished Member

    Aug 1, 2013
    4,538
    1,251
    Switching or linear supply?

    How much warmer was the power supply after 10 minutes?

    ak
     
  5. Baskaran Manoharan

    Thread Starter New Member

    Apr 18, 2016
    2
    0
    I am using 19.5V/4.5A(Laptop adapter) switching power supply only,For Load purpose i am connecting 100ohm/10W wire wound resistor,The load is only getting more heat,For ur reference i attached ripple waveform details
     
  6. BillB3857

    Senior Member

    Feb 28, 2009
    2,400
    348
    Has the power supply been out of usage for a long time before these tests? If so, the output filter caps may have "deformed" and after a while, "reformed" to a proper value. Electrolytics can sometimes behave like that. It is not uncommon to connect replacement electrolytics that have been in storage to a slowly increasing volgtage up to near the rated voltage of the cap. This allows the electro-chemical reaction needed to form the dielectric barrier.
     
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