EEVblog #594 - How To Measure Power Supply Ripple & Noise

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Great explanation well done

That was heavy (but fun). I have found if an auditing Piezo sounds 'normal', were golden. If the screech is too Bjork or Yoko then I find a Dave.

Awesome explanation of all the concepts!

Hi Dave,

Al video but can't find the information I need.

I need to measure some powersuppy noise. (cheap or RC equipment)
Yoi made the probes at 32min.
I think this will do but do you have a tutorial or pictures from this how you made it.
Type of coax (impedance) . Resistor and the capacitor you used?
Mabve buying a BNC cable
Cutting it in 2 pieces to start with.

Thank you in advance or any follower that replies.

Fundamentals Friday FTW!

Brilliant video. So useful. Perhaps I shouldn't be so disappointed with my digital scope after all! Thank you.

But doesn't the higher frequency noise count too? Especially for digital circuitry.

That HP calculator induced memories. Highschool programming, iterating math & stuff.

thank you!!!!

keen man

An awesome video that I have been watching since years again and again! Thanks Dave! :)

Dave, I really like your channel. Outstanding quality topics, content, judgement and sharing of your understanding and tricks. Thank you for sharing your excellence and passion.

Surface power supply can filter out all that switching noise . . . .

On the Tek 2225, that lowest division says "5m" which is 5 mili. That's not 500µ like you said, or am I wrong? Thank you so much for making this video and others. I'm subscribing!

If you're looking at a beefier supply and seeing worse noise figures could this be because the manufacturer is giving worse case and things will be better at lower currents? The TTI MX180T gives something like 4mV for its 20A output versus 0.5mV for the smaller MX100T and its 6A output.
So if I use the MX180T at 6A will things be a lot better? Maybe comparable to the 100?

Amateur radio receivers would like a low peak to peak. If I play with motors or power amplifiers (whether RF or audio) I'd like more current.

Question from a noob, Why not use shielded cables while testing ?

Nice T-shirt Sir

"marketing wank" .... i laughed my head off

....and this thing is a filthy SKANK!!

Are you ready to measure noise of any chemical battery?

It's very difficult to insult someone so much smarter than yourself wish he was my teacher

DSO!

Damn...Should I trash my low budget DOS, and only use my Tek2245A analog scope?!

Very simular looks and spec to my BK Precision 1692. Plenty of current, but some noise in the HF Bands.

Hey nice video. Though one more way to get rid of high frequency noise is to use a 0.1 micro farad disc cap on the probe tip. Infact you can solder it onto the probe tip and then leave a little bit of lead say 3mm extra to act as the points to probe the power supply. This is one of the standard methods

Hold on, why does the single probe give proper measurement, if it is also a lossy probe? Doesn't Agilent have 50 Om input? Becuase if it does, then you should have got same roughly 6 times lower measurement as with the differential probing. Please, explain.

Thank you

Will a true RMS ac voltmeter give a ballpark of ripple Vrms?

6 years on and your 'deep dive' stuff is still pure gold, I wonder if the UNI's around the world use this in their curriculum..they should..cheers.

Thanks Dave that was great.

hi nice video dave. Though in my company which made power supply for defense institutions and special custom built power supply. The way we would measure ripple is to use a single probe but solder a 104 disc cap on the tip ( 0.1 micro farad) on the tip. off course no use the ground lead that is serious a big ***** antenna.

Top notch and informative video, thanks

Hey. Why you do not suggest to disconnect probes from power supply to check if noise is picked up by probes themselves?

For the past month, i have been taking hundreds of measurements the wrong way for my university project. Even the professors or the research assistants didn't tell me any of this. How I wish I saw this video one month earlier. 😭😭😭

Isn't all noise common mode noise?

You, Sir, are a gift from heaven!

Why would using two separate probes in subtract mode reject common mode noise whereas s single ened connection would not?

Single ended connection still takes difference between signal and ground so if noise is common to both, it should cancel out right?

no book could have given such memorable clarity on these pitfalls.... excellent video Dave and the best part is its a free video )))

I miss Dave's videos like this

thanks a lot,I watch your video and learn so much

I made lm2678 5v5A but ripple shows for short interval, plz suggest me the solution

I was 8 minutes in before I realized you were talking about bench psu's not PC psu's...doh!

Great video! Also... where do I can buy a t-shirt like yours?

Thanks for sharing, Dave

Notice the screen scope is modulated by your voice a tad.

If I turn off the PSU I can see what is missing on the scope and deduce what the PSU is producing, I don't need to achieve a pure NASA lab environment to know if the PSU is crappy or not.

Great lectures. Definitely talented instructor.
But how do you get rid of noise??