Single-Ended or Differential Probe? Take the Mystery Out of Oscilloscope Probing
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- เผยแพร่เมื่อ 29 มิ.ย. 2024
- Differential probes aren't just for differential signals!
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What is a differential probe? It's a probe designed to measure a differential signal. But why are engineers everywhere using differential probes as general purpose measurement tools? Join Ally as she unveils this oscilloscope probing mystery.
Learn the three main values of a differential probe:
#1: Differential probes have a high common mode rejection ratio
#2 Probe loading is reduced with a differential probe
#3 Differential probes have higher bandwidth than single-ended probes
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Oscilloscope probing is arguably the most misunderstood but critically important aspects of making a good measurement. Take the Mystery Out of Probing video series, hosted by Ally Dartt, will unveil some of the greatest probing mysteries to help you make the most of your oscilloscope probes and improve your measurement accuracy.
#oscilloscope #probing #probe #oscilloscopeprobe #activeprobe #passiveprobe #oscilloscopes #howto #engineering #probeloading #differentialprobe #differential #singleendedprobe #singleended #commonmoderejection - วิทยาศาสตร์และเทคโนโลยี
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I use two probes for my differential measurements because my scope is from the Medieval times. I have to blink really quickly to capture signals into memory. 😂
Wow! I simply can´t get enough of these videos!! I will buy Keysight sooner or later!
I just cut the ground part on my BNC and other grounds on the PCB so it doesn't short the two grounds. I have a switch that allows me to reconnect the grounds. But obviously it also introduces some more environmental noise.
Keysight:
You are right on, in finding people who can articulate themselves so well and present technical aspects really nice in videos.
Good information in this video, I just love your videos.
Yes, what she does is in fact wary impressive, it take a lot of skills and talent. On top of that, you do have to know what she is talking about, she is not "only" a pretty face. Keysight, I hope that you know, what a gem you have there and that she do in fact make one to buy from you! :-)
Thanks for another quite informative and educational video.
You guys have a fantastic channel, and a great team of specialists, although I have to admit that Ally and Daniel are my favorite; They just look so into the topics they teach, that I could listen to either of them all day nonstop. Their enthusiasm keeps you engaged, and they know an awful lot about this (although knowledge of the field is something all your personnel has in spades).
PS: I really like how the video description is full of hashtags, as if somehow #comonmoderejection would eventually become a trend or a commonly discussed topic on social networks :P
Thank you!
Also, TH-cam has said their search is starting to shift towards hashtags instead of their normal video tags :)
Let's make #commonmoderejection a "trending search" then! :)
I love Keysight technology.
That make sense, thank you.
Beautiful!
And by "generally more expensive" you must mean "far more expensive." :) Differential probes must also have an advantage of performing the difference before hitting the scope's front-end, instead of performing a subtraction of two 8-bit values from the ADC. Perhaps that works into one of Allie's three explanations. I don't know enough about the subject to know for sure. Also, I could easily be remembering this incorrectly, but with the DSOX2 models, I think, that sample rate is reduced if using channels 1+2 simultaneously (as in the video) compared to using channels 1+3 simultaneously. Again, might not remember this correctly. If true, might apply if using the ol' school approach.
Good point on the channel usage thing, thanks for the tip! Price wise, both differential probes and single ended probes are all over the place so it's difficult to say much more than this without a stand-alone video.
I'm in the process of building a couple of high voltage differential probes for measuring mains level signals in 1 and 3 phase thyristor/triac circuits, and I don't want to use the two-probe method because then I would have no free channels to simultaneously measure other signals in the circuit (I have a 2-channel scope). There is no need for a very high bandwidth, 1 MHz would suffice, but it must be able to handle input signals of up to 1000V. I could buy the probes, of course, but building them saves me a lot of money (not counting the time to build them!).
Maybe I missed, but she forgot to mention about measurement of high voltages, when differential probes are also useful.
can I perform impedance measurement of rfid tag antenna design
great
Hello. Very Nice vídeo. Can you teste a situation of Hight Frequency Transient with one of your less espensive oscilloscope? Like a mini-motor conect to the eletricity home net.
I'm a geobiologiste and the so call "durty eletricity" it's an important matter of safety at home. I'm from Portugal and I'm already a fun. Thank you very much!!!
Try to test a DC to AC 3 phase inverter without a high voltage differential probe... boom! That's the time I learned from high voltage differential probes.
I would be sunk without differential probes. My work spans from high-speed digital to high-end polyphase power conversion. It is impossible to get through those designs without differential probes. The challenge is managing the cost. The probes used in power design are MUCH different than the ones intended for high-speed digital.All of them have non-trivial price tags but if you can't get the signal into your scope - you may as well not have a scope at all.
Hello everyone, for good you need a device with isolated inputs - and even for measurements of a wide range
Hi allie!
I would think math function would equally reject the common-mode noise. Please let me what I am missing here. How does differential probe reject common-mode noise better? How does the differential probe reduce the loading compared to single ended?
Two probes have their leads separated across a greater distand so common mode is different per probe. Differential probe has the leads very close together and are subtracted with analog circuitry instead of first digitizing them and subtracting.
I think the differential probes are better impedance matched for high frequncies. Two separate probes flapping in the breeze don't have a good hf return path.
make a video about current probe
So I’ve been trying to set up gains on one of my 4 channel amplifiers with my Oscope. When I use the regular ground reference oscope probe on the + and - terminal on the amplifier I get a reading that looks like 2 AC sine waves wth at are 180° out of phase. Would a differential probe help this?
Yes, a differential probe sounds like a good fit here. The ground lead of a single-ended probe is connected to earth ground, so if you connect it into a circuit you are grounding that part of the circuit to earth ground. For an amp, that will definitely mess up your measurement.
How are you using differential probes?
Keysight Oscilloscopes I use a 7 GHz diff probe for debugging RF chains.
"They are generally going to run more than single ended probes." - Haha... yeah... Especially so that I mostly use £10 probes, and save my precious £50+ probe for special occasions! :D
I am thrilled by the look on your face when you talk about differential probes. If that makes you happy, i will buy 2 of them but then i'd have to buy a keysight DSO as well! Well, i will but first i have to save some money! Great video. Thanks.
You 'can' float your scope by isolating the ground, right? Highly doubt that's recommend.
+carlylea definitely not recommended unless you really know your stuff! That would make for a great video, though.
I float my scope with an isolation transformer but this is mostly done to protect the scope
It's an important thing to check for if you buy a used scope. Some remove/tape over the ground pin on the plug. Some disconnect the ground lead from the mains connector inside the scope. It's a hazard in many ways.
Cant you just hook your oscilloscope to an isolation transformer? İt shoud make the oscilloscope floating?
Yes and no. It's floating, but the two channels of the scope still have their grounds tied together, and there is still some capacitance to mains earth, since whatever isolation transformer will have some non-zero capacitance between the primary and the secondary.
you can but shouldn't. the scope's power cord should be earth-grounded; and connect the device under test (DUT) to the isolation transformer.
Awesome 🎖
🤓cool
What are the wires (connected to the USB board) attached on the probes called?
The ground wires?
@@KeysightLabs th-cam.com/video/a28lVMsWFEY/w-d-xo.html
Dupont Jumper Wires.
These jumper wires are widely available on Ebay, Aliexpress, Banggood etc.....
also the connectors are available separately to make your own jumper wires.
@@BjornV78 Thanks, acutally I knew about the Dupont Jumper Wires, but on the video it seems that they are an integrated part of the probe. Am I correct?
@@KeysightLabs on the video it seems that they are an integrated part of the probe. Am I correct? th-cam.com/video/a28lVMsWFEY/w-d-xo.html
what is the cost of probe
We never*recommend* selling body parts to pay for test gear. Whether or not it pays off is a different discussion...
A bandwidth of 30 GHz! All the ones I've seen are 100MHz of less.
Hi! Why don't you connect the GND of the probe to the DUT, is it because you don't intend to use InfiniiMode? ( th-cam.com/video/a28lVMsWFEY/w-d-xo.htmlm20s )
Yes, that's correct. For a differential measurement, you only need the two connections.
Shes a great host for this video
She also wrote it!
@@KeysightLabs I assumed as much. It shows :)
I don't think it's just coffee
float the scope
Я бы показал ей свой осциллограф ....
This is the future of education: People that ACTUALLY WORK in the industry provide the education with examples, not all "theory" with 0 practice. Schools get abolished and instead you just pick a cool company like Keysight to educate you and hire you after, apprenticeships! Like ye olde times.
Alucard Pawpad
that would be equally terrible.
Why would it be equally terrible? I'm truly interested because I've favored Alucard's approach previously.
Kent VanderVelden
without theory you lose flexibility and (speaking outside the mere working purpose) cultire.
the first is very useful to draw conclusions and see, with just a pencil and some minutes, where something will go (an idea, a concept,...); it's super useful in understanding unexpected situations (i.e. if you really get the physics behind sonething, it's equal everywhere). this is also true for mathematical concepts, proves, theorems (which are super handy, even for level tables lol). without theory you form technicians, not thinkers nor inventors nor engineers.
the second is good for society overall, think about statistics or automations theory (hope it exists in english); they can be transferred from electronics to society.
Thank you Stephen. You certainly point out the flaw in my thinking. I had assumed that if someone was interested enough in a subject to become an apprentice they would follow their interest down the rabbit hole from practical to theory, and (I assumed) anyone in love with their craft does. But of course not many actually do. At my local university, in the ComSci program, they eliminated computation theory, discrete mathematics, theory of languages, etc. as they were found irrelevant to the creation of software engineers. (Similar degradation was done with EE and CprE to add liberal studies requirements.) However, I remember my argument for them being along the lines you state, that the theory is foundational, while programming languages and APIs, etc. come and go all the time. We mustn't teach too specifically, else we create workers unable to adapt as needed. And adapting is critical with thinkers, inventors, and engineers. Great discussion! Best wishes, Kent
Truth is somewhere in the middle. University is where science is done. This is the place where a new discovery is made. This is where you create the next Einstein or Stephen Hawking. This is the place where all scientists are. Yes their work is mostly theoretical but it lays the foundations for future technology developments.
On the other hand a production company like Keysight mostly needs engineers and not scientists! They need the kind of people who will get their hands dirty. They need people who take all this new knowledge and transform it into actual physical objects that performs some highly complicated task in a fraction of a second.
In short - everything around us is built by engineers but it is based on science. You can't have one without other.
hello Ally or whoever is replying, i'm working for Lear Corporation...and i would like to get some quotations for our 2018 budget.....can you send me your mail
Hi! The best way to get a quote is to go to www.keysight.com/find/contactus . That way, you can make sure you get connected to the right people for where you live. Thanks!
Alright ! thanks a lot.
This women sounds like Laci Green
With all due respect, please speak a little bit slower, you are not reading the newspaper or any boring storybook.
reading a stupid teleprompter..
snap er geen reet van
*B* *A* *E*
How is it possible to get to know you Allie? You are amazing!
I also like her voice.
Are reading script or you are gunious ?
Those aren't mutually exclusive! 😂 We often script our videos, but she was the person that wrote it.
@@KeysightLabsso she understand actally what she is talking about ?
Insted of modeling for this company just wander
Yep! She has an engineering degree
@@KeysightLabs wow makes me feel old anyway thank you.
This person is certainly related to Lexi Belle in some way.
Come on Keysight, Who is this chick?
She's a computer engineer and wrote & produced this whole video
She wiggles around more than a jittery trigger. I hope shes okay. Itd be a shame if she already had Parkinson grand mall or whatever
It's called excitement. If you were ever near me when I'm working on stuff I'm passionate about, you'd call 911, I guess.
If the music doesn't make you tap your feet, you are clearly tuning into the wrong station.
Beautiful!