Measuring ripple with a DMM?

Ethan · Mar 28, 2005

Is it possible to measure an AC component on a DC rail by setting the DMM to measure AC while measuring a DC rail? Is this an accurate measurement? Or is it just better to do the math? Just thought it would be cool if this worked... I wish I could try this out but I'm not at home at the moment...

Any ideas? Mucho appreciated!

BYacey · Mar 28, 2005

I do this all the time; it may not be accurate for frequencies other than 60 Hz. though. Usually you can evaluate how good the power supply electrolytics are based on this test.

gyraf · Mar 28, 2005

..yes, when set to AC measurement, your DVM will show the amount of AC riding on top of the DC rails..

Jakob E.

Greg · Mar 28, 2005

Wouldn't a scope be better for this, though?

gyraf · Mar 28, 2005

It would. But a DVM is much better than nothing..

Jakob E.

Ethan · Mar 28, 2005

Schweeet.
Just as I had suspected (hoped).
My brain is growing!!! [insert evil laugh here].

Ethan [when he gets home]: Honey, no time to talk I need to go measure RIPPLE!!!