Power Supply Board Ripple

Thread Starter

Baskaran Manoharan

Joined Apr 18, 2016
5
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?
 

wayneh

Joined Sep 9, 2010
16,128
Putting it another way, the question cannot be answered unless/until the load is known when the ripple measurement is made.
 

BillB3857

Joined Feb 28, 2009
2,506
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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