EEVblog - 2019-11-28
How to measure switching noise on a power supply properly, because Dave completely goofed it in the Riden RD6006 PSU review video. http://s.click.aliexpress.com/e/DlHrJpFS All about coaxial cable impedance matching and compensation. Mysteries of x1 Oscilloscope Probes Revealed: https://www.youtube.com/watch?v=OiAmER1OJh4 PSU Ripple & Noise Measurement: https://www.youtube.com/watch?v=Edel3eduRj4 EEVblog on LBRY: https://lbry.tv/@eevblog:7 Forum: https://www.eevblog.com/forum/blog/eevblog-1266-psu-probing-screw-up/ EEVblog Main Web Site: http://www.eevblog.com The 2nd EEVblog Channel: http://www.youtube.com/EEVblog2 Support the EEVblog through Patreon! http://www.patreon.com/eevblog AliExpress Affiliate: http://s.click.aliexpress.com/e/c2LRpe8g Buy anything through that link and Dave gets a commission at no cost to you. Donate With Bitcoin & Other Crypto Currencies! https://www.eevblog.com/crypto-currency/ T-Shirts: http://teespring.com/stores/eevblog
This is why Dave channel(s) are so good. When he makes a goof or oversight or whatever you want to call it. He makes ANOTHER and sometimes even MORE INFORMATIVE video on why the goof and delves deep into the topic. Those videos are almost MORE informative than the initial. I have so much respect for this dude and learn so much from these videos. Treasure trove for sure.
Thanks Dave!
I'm too dumb to think of doing it deliberately.
More to the point, this is an excellent example of the most illusive and unteachable of engineering talents, whether in hardware, software, medicine, cooking or dealing with the in-laws. That is to loudly and unambiguously acknowledge the problem, take the dent to one's pride, then fix it. In that precise order.
The trap for young players (or crap engineers) is attempting to fettle away a problem while desperately hoping nobody notices. The person who screams "I f****d up!" from the rooftops is 100x more valuable than the stealthy alternative.
@Chris Norman Couldn't agree more.
One of my pet hates is when a YTer regarded as knowledgable about a subject gets something wrong at the top of their voice, or as happened recently in one of my electrical subscriptions completely misunderstood how something slightly out of their field worked, loads of commenters point out the error but there's no response of any kind let alone an "Oops, sorry, I got it wrong" pinned comment. There's maybe a slight pause in output then continue as normal.
There's no shame in admitting you got something wrong.
@EEVblog , Nah... too crafty! ROFL
@Chris Norman Well put Chris!
David, I would really like to see a video on how to reduce the noise on the output of a switching power supply.
TheSignalPath made a video about this topic using one of the other versions of this psu
https://youtu.be/DPN1BERe6cg
Me too !!!!!!!!!!!!!!!!!!!
Jerry Walker did an excellent series of video’s about building a lineair power supply to replace the SMPS to feed the RD6006. This eliminates the inductive noise caused by the SMPS with great result.
https://youtu.be/Ow23O0EZeRE
+1 Common mode choke, caps, anything else that can help! Wanna see it all!
@Rd Tech Hahaha.
Personally, I've never done no mistakes.
@Steve Nope. Didn't explode.
you can use your action to prove that , haha
@Kosmonooit Hey... he ain't no politician!
@Michael Moore OMG... sooooo funny!
I personally just magic dragoned my first component the other night. 12V to a 5V TP4056. Stupid oversight of not putting the bench back at 5V. Personally, I'm glad I did. It gave me a chance to see just what kind of engineer I'll likely become and apparently it's one that's ok with making a mistake, admitting it and fixing it. Dave does this and he's fantastic so I'm glad I got to find out that I'm at least made in the same factory he is. ;)
If someone as sharp and experienced as Dave can still make mistakes it makes me feel a little better about my own stupid mistakes 😅
I measured the grid current with my little, yellow, china export meter once. It's too damn high! ;)
Well, it makes me sad knowing how many headaches I'm still to suffer.
@UltraMind Oh no shi-, your Harbor Freight free multimeter blew up when you plugged it in, too? That'd make three I've heard; two in person LOL
@Jim O'Hagan LOL, it's not that bad. I had my fuse well wrapped in foil, so what blew up is a trace on board. It was not one of the cheapest. It contained the explosion very well and the meter worked after that but I lost the small amp ranges ... hmmmm.
This meter died from a BEMF spike, which was kind of surprising.
First time ever I knew the correct answer instantly! I said "where is your 50 ohm resistor". All those years installing coax for Ethernet.
but this time ,he should use *1 probe and 20M bandwidth, we use this condition to test , it is less 100mv
@EEVblog Some 10-Gigabit cables are twinax
@gorillaau , You can always tell from the tone if the ring isn't correct. Just make it a token longer or shorter.
@grythumn After all the splitters, there is STILL enough signal to make it work... thank goodness!
Same here - years of installing coax ethernet, BUT termination resistor is ACROSS the core and shield not in-line with the core as Dave demonstrated with his 50 resistor at the PSU end. Also, for ethernet at least, it does matter where your termination is - should be at both ends of the line (unless the source is terminated inside the equipment). Have I missed something here or are my memories fading into the mists of time ? Or is this a different case ?
A video explaining some noise mitigations would be nice.
Yep, I'd love to learn more about noise types and common causes.
+1 on how to mod RD6006
I would love to see a video on improving the ripple from a smps.
And that's how we learn. Thank you!
Wiggle wiggle wiggle. Yeah!
JohnAudioTech 13:15
Would love to see how to improve on this Dave, thanks very much for this.
"Wiggle wiggle wiggle" - Dave
@EEVblog - I think you screwed up a second time - There exists specifications how to measure PSU Ripple and nois and your setup had almoste nothing to do with that. You had been just better !!!
"A trap fot young players", ugu :p :)
Some measurements in the frequency domain with no-, half-, full load at different output voltages would be nice.
I’d really love to see if this and how it could be improved
Like others have said - my favourite kind of videos.. "So, I goofed and here's why.."
Thank you for being such a great example to today's young engineers on how to handle inevitable mistakes.
I would really love a video about how to reduce the ringing on the supply. Please do it if you have the time!
great vid as always. you're a good teacher.
A quite nice video, thank you, Dave.
appreciate the integrity here Dave. An easy mistake any of us can make.
This is a great video, I fell into this trap (yep I'm a total newbie) only the other day, and now I know something new!
I've been there more times than you, Dave. LOL LOVE the remark by Steven Leibson, "Way to turn lemons into a lemonade video!" remark! SO TRUE!
lazy Dave is also wise Dave. (y) thanks for the information. trap for young players.
Very interesting! Definetly learned soemthong today!
Try to measure it differential with two probes. That is the correct way.
Please, do make the mitigantion video. I would be very interested and hopefully many others would too. Plus there's a hope, that RD could look at it and incorporate it into their next design.
Petr K , I'm sure a lot of Chinese designers would sure thank you a lot for doing their work for them!
Don't be to hard on yourself, here's a hug! :)
I just want to THANK YOU for all your videos. I've learned so much of electronics just because you decided to make this kind of videos. I hope life gives you back something of what you have given to me and many others that want to learn electronics in a different way. Big thumbs up to the EEVBlog
That’s the way to go Dave. I watch your channel since years. I like it very much that you tell your audience when you did something wrong. We all make mistakes and we can learn from those mistakes.
Top recovery :-)
After this second video I bought it.
From my experience in the technical industry, admitting a mistake and owning it is one of the rarest qualities. Thank you for demonstrating the right way to handle such a scenario, and using it as a teaching moment for your audience. All the best.
Here we go again, EEV price effect.
Almost 10 times difference, holy cow!
Is there any detailed explanation of what exactly happens here available somewhere online?
take a shot every time dave says "come a gutsa"!
Thanks for the follow up!
6:08 important to note, that the BNC feed thru adjuster has the built-in resistor soldered between the internal pin and the outer casing (in parallel), while the one at the PSU terminal is in series with the coax. So, when you say, you can add a 50 Ohm resistor to either end, it's worth mentioning, that at the PSU end it should be connected IN SERIES, while at the oscilloscope end it should be connected PARALLEL to input, that is between the internal pin and the casing. If you connect it in series, that won't work, and will just add up to the internal 1 MO resistance, hence same ringing will show up on the screen.
You always have good content. Happy Thanksgiving from the USA
Ah, coax... takes me back to my 10Base2 days....
We all make mistakes, it's what you do afterwards that matters.
Silly bugger lol :-D
Kudos to Dave for owning up!
So now you know what you son means when he calls you "DAD". 😂
I don't mind learning from my own mistakes; but I absolutely LOVE learning from OTHER people's mistakes. ;-)
Truly geniuses makes lessons from mistakes. Cheers Dave!!!
13:15 wiggle wiggle wiggle yeah! 😏
I'd still like to see that noise several orders of magnitude lower, given that it's a lab supply. Shouldn't be all that hard to filter out.
Still prefer to roll my own linear regulators and the subsequent power supply.
Steven Leibson - 2019-11-28
Way to turn lemons into a lemonade video, Dave.