EEVblog

[@EEVblog]

Yes, highly recommended. I wanted to cover the x1 mode issue that Doug and everyone else seem to skip in their talks that focus more on x10 probes.

[@keithwepking9988]

Thank You! You just saved me from trying to fix a local oscillator circuit that wasn't broke due to a low level reading on my scope with 1x probe at 36 mhz. I switched to x10 and there was my correct level! I really enjoy your videos.

[@envisionelec]

I've been using scopes for twenty years and never knew this. I was taught to always use 10x because of the higher bandwidth, and noticed it on the datasheet, but never needed to take the time to figure out WHY.

[@819jt]

Dave, you've taught me so much about electronics. Thank you. I bet no one at my college will ever cover this!

[@EEVblog]

Yes, it's big subject actually, and you could spend ages investigating how it all works and is optimised for best performance.

[@slinkytreekreeper]

So many answer to questions I didn't know I wanted to ask until you asked answered them. Very groovy Mr Dave you got my sub for the ride

[@richardmills5450]

That was fabulous. These are things we generally never find out the reason why. Cheers Dave.

[@electrocomm]

1X probes are not useless, they are very good for low voltage measurements, in order to keep the signal-to-noise ration as high as possible. Great video, though!

[@PeterWalkerHP16c]

+electrocomm What he said was switchable x10 probes are useless as x1. You effectively have a hidden 470Ω resistor in series with your probe, and as shown your 'low voltage signal' will sink into the mud of noise @ 10MHz so it's useless for low voltage work as well ... more so.

[@electrocomm]

+Peter Walker Agree, you might be right, the key word is "switchable", however, unless dedicated probes, these switchable 1X probes may not be quite useless; in a low BW (

[@irgski]

LaurMTB ツ as Dave mentions, for a true 1:1 "probe", just make your own out of a piece of coax cable.

[@PhilipBallGarry]

Thanks Dave. When I first started work at an electronics repair centre (many, many years ago) my supervisor handed me a brand new scope, then switched both of my probes to x10 before handing them to me.

[@thedjnk]

You should go into teaching Dave, I've learnt more in this video alone than a whole year in a master's EE course, keep it up!

[@gordslater]

excellent explanation, spot on. I had this explanation as a baby ship's radio officer in the late 80's in those days our radio and even some radar kit was lower then your average CPU FSB. - times change. This should really be compulsory stuff for new engineers yet as you say it's rarely mentioned, almost forgotten knowledge - tell us more Mr von Daniken !

[@otnica]

Dave, One missing element in your trasmission line analysis is INDUCTANCE. Impedance (Z) is equal to the square root of the ratio of L /C. The whole problem of BW in your case is related to matching (optimal transfer of power) the input and output Z's to the trasmission line. The 9 Mohms helps expanding the BW but introduces resistive losses, hence the X10. A 50 ohms coax will not help without proper matching or termination. I think it is time to review transmission line theory. Cheers!

[@EEVblog]

Low level signal measurement, e.g. 1mV/DIV. With x10 you trade signal level for more bandwidth, so your scope becomes 10mV or 20mV/DIV minimum

[@RAndrewNeal]

They're great for me, because I'm just doing audio (20-20k Hz) right now using an old analog 30MHz scope. I do want to do radio at some point though, so a 1GHz scope and probes would be nice to have when I start with it.

[@EEVblog]

No, it's all to do with transmission line matching and compensation. The probe is transmission line optimised for x10 mode, so is all mis-matched when you switch to x1.

[@famossfla]

Thanks again Dave.... Your video's are much appreciated. I learn so much information each time. Keep them coming... Your a fantastic TEACHER.

[@danedewaard8215]

Sometimes the route is much more enjoyable than the destination!!!! I'll not take for granted the X10 scale and will think thrice before I use the X1!!! Thanks so much!

[@gamccoy]

I loved this video. I know a fair bit of theory and thought we were going to get into rise time limitations of the R/C compensation. I NEVER knew about the deliberately lossy transmission line. Dave, please do more theory vids.

[@DarkInsanePyro]

Thank you Dave for this excellent video! I love all your videos but it is nice to pick things up like this which weren't discussed in the university (unfortunately). It may take some work but I'd hope the appreciation from the community encourages more in the future! Thanks!

This is very usefull information, THX a lot. The resistant core of the coax also helps to block from signal ringing and mirroring at the input of the scope.

[@RachelMant]

Very grateful for this video seeing as I'm currently playing with building an 80MHz RF front-end and was wondering how best to model probes for LTSpice to understand what voltages the ADC will be seeing. Nice one Dave!

[@GaRbAllZ]

Brilliant explanation Dave. It would be great to continue this by explaining differential probes, how they work and possibly design one to build. Low frequency of course.

[@jabatta1]

Thank you for answering this. Had trouble finding this anywhere else. Didn't realize a coax had so much capacitance. This threw me off on a high impedance measurement when trying to use 1x mode, now I know why.

[@mikeselectricstuff]

100x is also useful for low voltage sensitive ccts, e.g. 32K xtal oscillators and micropower /low leakage stuff. For low voltage, low frequency use, a 90M resistor in series with the top of a 10x probe is a cheap option.

[@EEVblog]

Yes, the 50ohm coax of course needs proper termination to work well, a whole other topic. As is the transmission line matching.

[@TheMadMagician87]

"Now, the first thing you should say is, well, bullshit; show us!" Thats gold, love it!

[@ib9rt]

The x10 probe reduces the signal amplitude by ten times. This forces the scope to amplify the input signal by ten to get back to the original scaling (which means it will also amplify any input noise by ten as well). So the x1 probe is more sensitive and can capture low level signals with better resolution and less noise.

[@MrSoundshark]

I had so many issues with transmission line theory when i was working on my degree its a very difficult subject

[@gamingSlasher]

Blew my mind. I didnt have a clue about that. Never bothered to measure probe resistance. Excellent.

[@deltaxcd]

I would say that everything is little simpler, since i had to design my own cable for oscilloscope probe. Most important feature of lossy cable is to have very low capacitance, so wire must be as thin as possible. If you try to replace it with regular coax you still can compensate everything for any bandwidth but input impedance will be terrible, what makes measurements impossible( done that and was puzzled why everything stops working when i attach my probe) probe impedance is basically cable impedance divided by multiplier. lossy cable allows you to achieve higher input impedance resistance does not seem to play significant role however it ensures that there will be no reflection because of improper termination and also it may improve impedance by turning cable itself into atenuator

[@PafiTheOne]

Interesting to see how the pure truth not earns many thumbs ups. I add some other (probably even less popular) fact: the other reason of the high wire resistance is the material choice. The wire must be strong and flexible despite of the very small diameter, and also not soluble in tin during soldering, this is why it cannot be made from copper, but other materials with higher specific resistivity must be used.

[@Deckardsvr]

Dave, that was hugely informative, thank you

[@PlasmaHH]

Whenever I simulate things like this I am wondering if group delay should worry us too...

[@vex9060]

Thank you! Please Dave continue with this stuff and explanations! Greetings from Bulgaria!

[@JMaldonado64]

Another reason why x1 probes are designed that way (internal lossy transmission line) is protection of the sensitive input circuitry of the oscilloscope. A direct coax cable surely has the best bandwidth, but it will also allow anything to pass, including signal under test as well as any static HV peaks which might easily damage the ESD devices inside the scope. The design of ultra-high bandwidth/high gain voltage amplifiers combined with effective protection circuitry is a form of art in the electronics world.

[@edhalferty]

Awesome video! The diagram with the lossy transmission line modeled as a series of RC circuits says it all.

[@johnburt1547]

Great video Dave, I'm glad you explained this. Yes, the big white board on the wall is much nicer.

[@EEVblog]

Do people prefer that one to the old hand held one? I think it works much better.

[@fullwaverecked]

Dave's probing genius rocks! Thank you for the video!

[@nerobro]

Dave, this was great. You do tons of entertaining things, and you do them really well. Your educational stuff is absolute gold. Keep it up.

[@joeykjoseph]

Love the explanation, Dave...

[@NerdNordic]

Holy crap, I learnt so much! Thanks Dave! Btw: Could you do more videos like this?

[@EEVblog]

No, you can roll your own. I've done a video with Doug on high voltage probe design.

[@ovalwingnut]

Back for a "2nd suck of the sav". Good stuff! Ok, I'm a slow learner. Re: wiggle wiggle center conductor. I was told back in the day (elect shop) that the wiggle was to help [center] the conductor in the dialectic more consistently. On some coax's they will include a plastic/teflon? spiral to do the same thing. That being said I like the "flexibility reason" too. Could easily be both 😁 Thanks again for the gray matter re-charge. Cheers. 🇺🇸

[@EEVblog]

No, usually not. Yes, the odd shuffle was required in this one.

[@gordslater]

it's a phychological, measurable effect. It depends if you are natively a right-to-left or left-to-right script reader. eg: English readers seem to prefer lecturer on left, info on right, Arabic readers seem to prefer the opposite. It doesn't make much difference to most people, but I was told years ago to present pre-drawn boards from the left if I don't want to "get in the way" (and that doesn't mean physically). Personally I don't notice a difference but swapping sides is distracting to me

[@snaprollinpitts]

thanks Dave, I had no idea about probes, but you're right about those switches on the probes, they can drive you crazy.

[@abelincoln7473]

Electricians tape tends to fix that problem: set it, tape it, forget it. Also that strip of red tape is an easy way to know which one of the probes in the box is set to 1X

[@garylcamp]

Thank you Dave for pointing that out. It is useful to know the X1 is so low BW and that a coax is actually better in low volt and hi BW applications. Non intuitive. I love your blogs ( I love your accent, LOL). BTW, how do you pick coax for that condition. 50ohm, 75ohm, etc.

[@ronniepirtlejr2606]

They have a special coax just for data transfer on satellites. Not sure of the resistance? but it has double braided Shield 100% copper with 100% copper wire in Center. It's about less than half the diameter of a TV cable wire.

[@briantamburelli7573]

Thank you Dave. I learned something I didn't know.👍😊

[@cameronboone1230]

I was right there with you until about the 24 minute mark. The scope probe as you mentioned is a distributed, lossy transmission line. You measured it to be around 330 ohms at DC / low frequency. It will be different at higher frequencies and as you mentioned is optimized for 10x mode and to achieve high bandwidth. The characteristics of the transmission line, however, are determined by geometry and materials and are the same whether you are on 1x mode or 10x mode. The transmission line doesn't look any different at 20 MHz (just picked a number) in 1x mode than it does at 20 MHz in 10x mode. Which means the effect of its interaction with the 15pF scope input capacitance would be the same at 1x mode or 10x mode. Also, what you are changing between 1x and 10x mode is whether the 9Meg resistor and ~15pF tip capacitance are in circuit or bypassed. So wouldn't the bandwidth limitation in 1x mode have to do with the interaction between the lossy line's RLC and whether or not the 15pF tip capacitance is in-circuit or shorted, and not the interaction between the lossy line and the scope's input capacitance? If not, what am I missing? Great video in either case. Thanks for posting.

[@paulbendel]

Now I am 10x more optimized to watch another EEVblog!

[@youssefdirani]

10x means divided by 10

[@daveoatway6126]

very useful video. A series on sources/corrections for measurement errors would be a good video/series.

[@KeritechElectronics]

And again, I hope I learned something! That was useful and most informative - thanks a lot :)

[@MinhTran-wn1ri]

If your signal contains frequency components higher than the probe's bandwidth (in x1 mode), the signal will APPEAR attenuated and 'rounded off' (on the DSO) but the signal itself is unaffected right? It's just a case where your probe isn't good enough to 'resolve' the higher frequencies (e.g., in the case of a square wave, the higher-frequency components are what makes the corners sharp).

[@SeanBZA]

Eric Wasatonic did a fascination series on building his own x100 probe as well. Look at this series starting 25 Feb 2013

[@kraftrad7840]

Very interesting! Nobody in my company (one of the aorld leaders for telecom base station power supplys) could explain me this "phenomen".

[@naftilos76]

Hi Dave you never said anything about the 50 ohm resistor of the signal gen. That should be included in your calcs in order to be more precise on the -3dB point. I have seen a lot of your videos. As always they were extremely helpful. Thanks again.

[@ronniepirtlejr2606]

I am no engineer. But what I picture when you're talking about this is Eddy currents going back and forth. Or electricity, A/C ...It can only travel so fast on such a thin wire with such a great resistance.

[@andrewverran3498]

Brilliant info...so what is the advantage of having ORIGINAL probes , say for a Tektronic 465M if it did not come with original probes? Cheers

[@dolbodolb6173]

23:30 so the equivalent circuit is a low pass filter R=330R C=15pf. Did Dave forget to add the coax capacitance? 330R 80pf sounds more like it to give the correct 3db bandwidth. Otherwise it sounds too high, about 30Mhz.

[@patriciogiron7304]

Great tutorial thanks we learn somethings every day.!!

[@521cjb]

Wow, didn't know that, now I have to go measure R on leads of my brand new Siglent. I just wonder if that resistance wire is Ni-chrome, same resistive stuff they use in electric heaters and blankets - easy way to tell is, try to solder it, Ni-chrome absolutely will not stick to normal solder. (if you ever wreck an electric blanket, salvage the resistance wire, but you have to crimp all connections.)

[@ronaldlijs]

Good stuff, well explained and showed. Keep them up Dave!

[@TonyButchT]

Good subject to investigate and a Great presentation! Thank You!

[@mahoneytechnologies657]

Good to mention this, anyone who works in electronics has to know this, otherwise they should never have been hired.

[@andreydorokhov6084]

Hi, Dave! In case of x1 position, you say about voltage devider model with cabel distributed 330 Ohm and 1 kOhm capacitive resistance. But what about x10 position? If we discuss with voltage devider model, it shoul be 9 megOhm + 330 cable distributed Ohm resistance, so that thing makes signal almost zero amplitude. How it works in x10 position?

[@simsys_outdoor]

Hi Dave, You didn't do one thing when you damage this probe already: measure the whole lenght of this inner cable. You will be suprised how long is it!

[@alexeyveseliev106]

I understood why 1x probe has norrow bandwidth, but why 10x has wide? Because the capacitor in the tip?

[@frab88]

it depends on the compensated attenuation that you have with the 9Meg resistor in parallel with the capacitor. www.ni.com/white-paper/14825/en/

[@AIexanderHartdegen]

When your probe is used in 10x mode, there is attenuation, cause the resistor and the central wire (or tip, or cable end) resistor equivalent make a drop signal. When you increase frequency, you will always have the amplitude loss, but because the tip capacitor, let transmit a part of original signal, wich is more conductive when frequency is high. So, even if there is attenuation in the cable, your signal will be less attenuated by the tip capacitor, until becoming a simple wire, making a very flat response at the end of frequency range.

[@iliazark1]

What kind of a reistor is that 9MOhm in the tip of the probe. I am guessing if I put just a common thin film resistor from aliexpress, the inductance would mess up the measurements. (I blew up a 10x probe and I am looking to fix it for fun and learning, but I can't really find spare parts for it)

[@Cybeonix]

Awesome stuff Dave, really enjoyed this one! Whiteboard looks great

[@gfmucci]

So, is it best to get dedicated separate high frequency 1x and 10x high frequency probes if you need to test high frequencies?

[@sanketpatadiya8168]

Learnt EMT + Control system + Network Theory in one video, Thanks

[@onwul]

So basically what happens is that at x1 mode, more electrons have to travel at a time through the wire, because wire is too thin, it can't handle electron traffic. At a x10 mode, less electrons have to travel, so wire can handle the traffic. Have I got that right?

[@InterCity134]

So the more critical question I had was given the 1x setting appears crap in all of the Parameters then what is the corner use case for ever needing the 1x setting at all , why bother shipping the scopes with 1x as an option and not just fix them to 10x? Is it correct that it only matters with very weak signal levels at the very bottom end of the scopes capability? (Which by definition also have to be low frequency)? So what when scoping the output of a microphone diaphragm?

[@gordslater]

yeah agreed, newone is very pro but please use the old one for special quick spur-of-the-minute squiggles now and again for some nostalgia :)

[@peterahjorter]

You are a true god of electronics!

[@hirofumimomose5014]

And this is why scope probes must be handled carefully. Center conductor is so thin.

[@jmoconcept6672]

Learned a lot. Thanks.

[@RandyLott]

I like this DaveCAD-HD! It looks great.

[@kaveag]

Hi Dave, can you make some quick video on measurement of smd capacitors and coils?

[@roamingbear]

Did you what, watched like 2 of them? They are all great!

[@dartplayer170]

I have an old analog 20Mhz scope and I measured the BW of the probes to be 500kHz on x1

[@MrSparker95]

Thanks for the video! But I can't understand how a passive circuit can have higher amplitude at the output than at the input. I mean the 'funny business' at 27:45, but I get the idea what was meant.

[@undercrackers56]

Since I am fairly new to electronics I am trying to understand oscilloscopes and probe use. I watched this with keen interest, others concerning 10x probe use and even W2EWs video about the effects of ground lead length on signal quality. Frankly, I still can't quite understand the value of 1x probes, rather than just using a 10x probe for everything. What am I missing? Many thanks.

[@mtabernig]

However coax will change impedance at large change of frequency. The "crincle" form choke points in the signal that changes with the frequency. the cables are rated at 50 Homs up to 900 mhz 5

[@EEVblog]

Didn't think about that, yeah, I've swapped sides!

[@Pawel5837]

😊 Again. Where that 1k resistance parallel to the oscilloscope input comes from?

[@das250250]

@25:18" It doesn't matter a rats ass" ... gold aussie Tech talk hehe love it

[@JLB309]

You could use them both, sort of picture in picture white board.

[@hygri]

Excellent video Dave!

[@roamingbear]

Excellent! As always! Thank you!

[@remontlive]

Your videos is a brilliant youtube mine. 👍🏼

[@BrettW]

Waling off at the end like a professional you tuber. How stylish.

[@11bogdog]

So, if I need an x100 oscilloscope probe, the only sollution is to buy one. Is that right ?

[@cbureriu]

you are missing the scope ground in the probe schematics

[@laharl2k]

smaller voltages measurements most scope go up to 5mV/div, in x10 thats microvolts. HF x1 probes would be useful for that, a 20mVpp sine wave is at least visible in 4 divisions instead of half (2mVpp) at least that's what come to my mind.

[@Raldenaldrin]

how the scope probe was connected in the oscilloscope?

[@laharl2k]

the ipad's ADC (aka the sound chip) doesnt have the sample rate required for a decent measurement. you will get at most 48 Ks/s which is the sample rate of the sound chip, the same goes for the sound card oscilloscope. the KHz is the sample rate, not the bandwidth, you'll surely have more than that of bandwidth but without the sampling rate, that's useless. The cheapest chinese scopes come with 500Ms/s and 1Gs/s, and 1Gs/s is the minimum recommended for almost everything in general.

[@gearstil]

Very useful video!

[@MartijnDecauter]

Hey Dave, at 23:10 the video jumps from having a 15 pF tip cap to a 1k Ohm resistor. What is that about? What am I missing?

[@TheMrTxM]

Hi sir, When you fill in the formule of Xc = 1/2pifC = 1/ 2pi10MHz15pF you get 1k ohm. So you can replace them for the equivalent reactance.

[@MartijnDecauter]

@@TheMrTxM Thanks for your reply :-)

[@JakobWierzbowski]

Mr. Jones, thank you! :D