Ripple, how much should we be concerned with?

Off-topic Chatter
1

Messing with some AC drivers lately, found this indirectly linked mysku.ru article in there.

The article author found “high ripple” (8.7%) coming out of the reviewed driver, and he fixed it by adding extra capacitance (namely at the primary).

Question is, how much is this of a concern? I understand a high ripple decreases efficiency, increases heat, lowers output and etc. but, in practice, at least for the AC driver this is no big deal, or does it?

I sort of find myself driven to buy some 400V caps to fix a few of these drivers now LoL.

Concerning flashlight drivers, I've also found myself adding some proportional extra output capacitance when increasing current output in buck or boost drivers. I thought it would help, but I'm not sure how much as I've been told the increased noise from the switcher may still remain.

Any wise thoughts?

2

that small amount probably not detectable by eye.
a camera will likely show banding.
a bigger cap on the input reduces the 100-120 hz ripple.
this is what causes banding on cameras.
the output is to high freq to matter but the 100-120hz ripple is superimposed on the output.

3

Thanks for chiming in snakebite, I was about to order a 20x 400V 15µF capacitor pack, I have a few drivers to fix. Just shot.

I find this lack of primary capacitance somewhat astonishing, but everything has a reason. They must be saving some good dimes by cutting corners with the caps, doesn't it?

4

“Ripple, how much?”

Oh. I thought this thread was something else…

5

WTF is that? Some sort of wine? Another subtle venom then.

They even show cigarettes in the picture, that must be some pretty old ad poster design.

6

It was a “fortified” wine, often consumed directly from the bottle while sitting on a park bench or the sidewalk.

7

Low ac-dc driver ripples is not about effincy or heat, this is about health. High quality IKEA led bulbs outputs 2…4% ripples, chinese bulbs (with no driver board and few components mounted on led pcb) can go up to 80%.
Yes 2% ripples gives much more comfort to eyes that 10-12%.

P.S. From the other side, all smartphones with amoled display have low quality pwm brightness controller and ripples goes up (as brightness goes down) up to 80%.

8

Thanks for chiming in kiriba-ru, now I essentially understand why I got interested in these matters after inspecting some drivers (the health stuff). Time to fix a few of them.

WTF? I am using an amoled display smartphone. Time to somewhat limit my usage of it. :-|