A basic DSO has maybe 300 uVrms noise over 100 MHz bandwidth, which is a spectral noise floor of 30 nV/rtHz (assuming a brick-wall filter), if your DUT is quieter than that you can always add an LNA.
On Fri, Oct 14, 2016 at 2:59 PM, Chris Albertson <albertson.ch...@gmail.com> wrote: > On Fri, Oct 14, 2016 at 11:00 AM, Cube Central <cubecent...@gmail.com> > wrote: > > How would one go about testing power supplies and seeing how noisy they > are? I have the standard suite of tools, an oscilloscope and a little > (dangerous) know-how. I am just not sure what to look for or how to safely > hook it up to test. > > > > You'd ned a spectrum analyser. You could assemble one from parts > that are used for Software Radios. A USB TV tunnel dongle and a > computer and a good mixer and clean oscillator. With hat you'd be > able to characterize noise from DC to about 900MHz > > Those with more money than time would just spend the bucks to buy an SA > > Those who don't need numbers would just look at the DC on a scope and > "eye ball it" and say "wow that is noisy" or "wow that looks clean" > > In all cases you'd want to put a realistic load on the power supply. > But what is that? I bet if varies a lot. > > And like I wrote before it may not even matter as phones don't > directly use the 5 volt DC that these chargers produce. > -- > > Chris Albertson > Redondo Beach, California > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.