These are amazing videos. So much information and experience to be gleaned from these. Thank you Dave and hope you and the fam have a great weekend!

Been there, seen that. In the late '60s I was on a team building a drone navigation/autopilot system based on Omega Navigation technology. (GPS gear was too expensive and bulky.) This was in the USA but the company, which had been strictly building analog telemetry radio links, was bought out be an Italian company that built the airframe. They wanted the USA electronics knowhow. The owner of this company insisted that all the new test equipment be made by HP, so our scopes were, of course, HP scopes. We had a big sheet of plywood with all our prototype electronics bolted down to it to simulate the airframe and there was three separate systems avionics boxes mounted there with the electrical cabling connecting them together. We had the whole system working together and were still testing and updating the software. One day we started working in the morning but everything had become unreliable. Stuff would work for a while and then the software in one system or the other would crash. We were baffled for quite a while. We kept asking the various teams what they might have changed that could affect all the systems this way. Nobody knew. We kept thinking it was noise in the power system. Finally the right person heard the story and said, "Oh, we changed out all the fans to brushless motor type. We hooked the scope to the power line but it looked just fine, smooth as silk. One of the engineers said that HP scopes weren't fast enough to see the noise that might be there. Well we got a Tektronix rep to bring in a 'scope, a 465 to be precise. We hooked it up the same way we had connected the HP scope and ... nothing. But then we turned off all the lab lights and turned up the the brightness on the scope and there it was, a sharp little glitch riding on the power. Needless to say, we bought some of those scopes. The fix was pretty easy, just added some filtering on the power. I don't remember the details of the fix but I sure remember that 'scope.

Chineese takeaway oopsie protection. Never change Dave. 😂

This is also a good example of why you should be aware of the sampling rate at the current timebase, and that using peak detect acquisition can help to see this sort of glitches.

This is something I think is often forgotten (I do sometimes forget this for sure), that the signal that enters the scope is split up in 2 paths. One is just for triggering and such stuff, and the other goes trough the processing circuitry and is what we actually see on the screen.

I hate it when things happen Premature.

I seem to remember some scopes, may have been before digital units used to have a button for trig view which put up an extra display beam to specifically show what it was triggering on.

Good video - useful to be aware of this potential triggering.

New title: “why doesn’t my scope trigger correctly?”

Very interesting. I wouldn't have thought the trigger and display circuitry were separated like that, but it makes sense now that I think about it.

Fun, informative, educational, as (almost :)) always!

Wow this brings make memories as back in the eighties I was building a digital scope for my final project and it did glitch. As a poor student the cost of the fast static ram was so expensive that can remember taking out with extreme!!!!!!!!! care in my lab time.

Thanks Dave, i've learned so much of this one :-)

Thanks Dave. I am a newbie, this helped me to look with greater accuracy at some glitches I am currently looking at. 😁

Really love your explanation. Loved this video.......thank you....

I needed this info a week ago when I was getting premature triggering.

Cool video, something to look out for. I will be doing exactly this once I get my arse into gear.

Nice video! Some time, i have also some trouble with common mode interference, i put many ferrite on probe cable and make great difference in reading and triggering. High DV/DT and high DI/DT circuit is always a chalenge to probe.

Very useful !!!

Real men have "chinese takeaway oopsie protection" :)

This is a good topic. Perhaps Dave or others could look into how ground strap layout changes could reduce the area/space in which induced field is entering, thus causing the EM noise, maybe wrapping the ground strap around the probe or taping it down. It also leads to possible discussions on improved PCB layout design for probing points in these types of boards, eg. having a ground point very close the the probe point and using a spring-type ground "lead" attached to the probes tip ring. Of course that does not help in probing around other points on the board that are not official probe points... Cheers Dave,

The application note AN47 written by Jim Williams has a really useful chapter about all kinds of probing techniques including a "organic" probe. If you like this video, you'll probably love the AN47.

Always use peak acquiring mode to capture the glitches, instead of faster timebase or memory depth

2:50 "Waveform extended to the maximum!" Fan-freaking-tastic! lmao

I'll admit I didn't guess the answer at first, but I actually had the reverse problem a few months ago at work.... I had HF reject turned on, and my scope (Keysight DSOX3034T) wasn't triggering for the transients I was trying to capture. I didn't consider them to be that high frequency(We're talking 10s of kHz) but the integral over the trigger point would've been relatively small, so apparently the trigger level didn't stay high enough long enough to grab the transient, yet I knew it was occurring because I was still experiencing a failure mode I had already characterized.. I might've ended up adding an RC filter to the input, but at the frequencies we're talking, a 5 degree phase shift is not insignificant (200Hz for the main signal)

Dave, if you use a pol filter on your camera you can almost totally avoid the reflection on your scope screen or other reflective surfaces.

Also don't forget you have the filter enabled, how much time will one waste trying to troubleshoot a bandwidth issue. Ask me how I know... Great video, good to see back to basics again.

I usually set the trigger level to just below the expected signal level. Not the avoid this sort of issue, but for things like tri-state logic. Perhaps you could make a simple test jig to re-create this issue, something the EE students could do in the lab with a signal generator and and inductor.

The teaspoon in the football field. Such a runt pulse in a long time base.

And this is why there's no excuse for a scope not have external trigger input! All it costs is 1 BNC and 1 relay and just goes straight into the trigger circuit.

Nice Shirt!

Long ago I worked for a company that made systems normally sold into 60 Hz markets. When we won a large 50Hz order, the customer insisted on a long-term 50 Hz test run to ensure completely normal operation. We chose to use a large diesel generator whose output was extremely noisy, some of which made it through the system's power supplies. We soon learned to keep HF Reject permanently on.

I am new to electronics, can you please make a video about waveform capture on oscilloscope (I don't know anything about trigger)

I would also try Peak Detect Aquisition Mode. Maybe it would catch this spike.

I think there ought to be an alternative trigger mode that is based on the digitized data from the ADC instead of a separate analog trigger circuit, perhaps should even be the default mode and then use the analog trigger if you want to find spikes and things that are too fast for the sampling. Also the HF reject should adjust its limiting bandwidth according to the sampling rate, and I think it does in some scopes.

I was curious as to weather or not it was the mains switch being turned on that created the false trigger. Well, in part due to the long ground lead.

20 or 200MHz probe BW limit is your friend in many cases :) Even Mr. Nyquist approves when the sample rate > 40 or 400MS/s

This is one of the reasons I sometimes hate to think in terms of memory depth when I set up an aquisition. Just keep an eye on the sampling rate if you know what kind of content you expect(or don't expect) and the maximum timebase will be limited by the amount of memory available. If you do it the other way around and just set the maximum memory you will be tempted to increase your timebase at the expense of sampling rate and then wonder why you miss glitches. In other terms: never acquire events on a single timebase/sampling rate; always explore your signal: increase de sampling rate, move the horizontal refference, zoom out, zoom in.

Can't think of a good use for noise reject? You actually showed a good use for it earlier in the video: 2:27 and 4:14 :)

Hi Dave ... if you put the osciloscope in peak detection i think it will show (ate list they should) show the glitch eaven whit low memory or low time base ... it was in these mode or not ? regards from Brasil.

+1 for probing tips video

Warning! The High Frequency Reject method may not work for all kinds of premature triggering issues, especially if you are probing out of your league.

What is that HDMI like connector labeled Sbus on that Siglent?

TRIGGERED!

Problems I don't have on my hameg 604

Lovin' the plastic microwave proof container over the PS

Hi from italy dave

Why not use the peak instead of normal capture mode to see what your missing?

And here I am stuck with an old analog Hitachi scope from the early 80's with no capture at all. Gotta stop being cheap and get on board with this newfangled digital stuff. 8) Nonetheless, you've given me a lot of good info on how to use my CRT scope better. I love all your videos. Thanks!

now dave before you give it away; is it something with pretrigger time also (not related) i just found one change with youtubes ad system: they asked if i want to see midroll ads or watch 3 ads right before the thing. lol. but there is a way to get around it without adblockers i found out; lets just say that you will learn to love construction side cones (disguise is neccessary here)

My fully digital Hantek does not suffer from these kinds of bugs, since it does not incorporate the inferior analogue trigger circuitry of yesteryear.

Why can't we just trigger digitally from ADC output?

Here in the lab the noise of the led lights is so big that it is almost impossible to trigger in small signals when they are on

would a CRO show the same?

why electronician have so many scope ?

Nice oscilloscope

Wow. That must be a one narrow pulse that it cannot be seen with a 10ns/div timebase. I wonder what phenomenon is responsible for generating it. ...maybe some Diode Step Recovery effect.

A slightly off topic question: How would you contrast your Keysight MSOX3054T vs a MSO of similar performance from Rigol, say the Rigol MSO/DSM7000 500 MHz, the MSO8000 600 MHz, or even the MSO5000 350MHz? The screen on your Keysight looks TERRIFIC but I’ve never seen either the 7000 or 8000 series side-by-side with the Keysight. I hope you’ll comment or point us to existing EEVBlog episodes I’ve overlooked. Keep up the great work and content. I’ve known engineers as talented as you but none so willing to share and mentor others!

Maybe little tip, but if your scope doesn't have a HF reject option (or it'snot good enough), you can just easily make one yourself from some passives on the external trigger.

Why not use sequence mode in this case? Seems like capturing the waveforms from each trigger would have been more straightforward...

BTW, When I was a Field Sales Engineer for Tektronix people would ask if we made 12” or even longer Probe ground leads. I’d say sure we do. Do want to buy some for someone you don’t like much?

Hy Dave, how do I see that 35 minute video you were referring to?

14:14 So what's the neat little trick for people with only two hands to aid with probing? :)

One of the constant "features" of digital sampling. I love the advantages but you have to remember the limitations too.

I love the chinese takeout oopsy protection 10/10

Get a scope that triggers in the digital domain.

I thought they had tablets for you to take for that problem Dave...😂🤣😂🤣😂🤣😂

Geee you sure get some really nice toys... thanks...:)

Sounds like something you might want to talk to your Doctor about.

im too stupid to understand but i like it

What is he saying at 2:40 something like byula or bulla? What does it mean? It driving me nuts.

Huh your second channel's purple on your siglent, silly question but how can I change that? xD

A food container for safety, great idea!

couple of more Dave videos, and I'll be electronics engineer

The problem is the fact that your using 2 different scope probes, one has a different propagation delay causing as much as 5 minutes of skew ... ... well at least thats what my old professor made it seem like when he marked me down for using probes that were not "matched" than probing i2c at 120khz :P and yes, im being a smart ass

That premature trigger will get you every time. 😏

Nothing more embarrassing than premature triggering!

i am offended about all this triggering ITS CURENT F*UCKING YEAR

"got your noise!" should be the electronics engineer equivalent of "got your nose!"

Tachyons. Got to be tachyons...

There's absolutely no excuse for integrating a noisy and unreliable switching power supply when there's room enough for integrating a real (linear) power supply.

😲 Once again, I did not know this... I DO NOW! Thank You Canadian Factoid: {TRIGGER} A Lennoxville`s (Quebec, Canada) Burger: Go to McDonald's, (Macca's!) order a Junior chicken burger and a double cheese Burger. Stick the Junior inside the double. You have a trigger!

ottima idea la ciotola del gelato

I am sure there are few million people who need a filter to reduce their false trigger levels lol

I tried this, and now my oscilloscope is upset with me, calling me all sorts of political names ): I guess triggering it wasn't such a great idea...

This happened to me the other day. I called all my colleagues to the lab to show them the problem I spotted with our product. It happened once in a system test last week and I had spend days trying to track down this intermittent problem. The scope was connected so I turned the system on. I set the mode to single and we waited for a moment. The scope screen suddenly showed an image of all the probed waveform, but everything was normal. Premature triggering...I was so embarrassed.

If your oscilloscope is triggering prematurely, try thinking about baseball.

Meh, this video is so basic... pft, it was obvious from the beginning. Dave, after all your lessons, no one falls for that one :) (just kidding - great video, especially for the newbies)

When an oscilloscope is more easily triggered than a snowflake...

DIDT DVDA? kzfaq.info/get/bejne/m7CFgKx9sJ26m5c.html

Anybody else reading the comments, looking for the jokes about safe spaces?

Dave, that's what you get for using that new newfangled DSO rubbish. I'd have captured that easily with my Tek 7844 CRO with P11 Phosphor (blue) and my trusty Tek scope camera and Polaroid film. I'm guessing some unimaginative viewer will regurgitate a worn-out boomer comment as they can't fit in a legend has it...

Dave is back! I'm so happy. I thought this channel would slowly fade into nothingness and now Dave is making interesting technical videos again!

What would happen if the ground connection was looped through a doughnut like this one? KZfaq: BewyFge5MFY

Premature Oscilloscope Triggering = Great name for a porn film?! 🤷‍♀️

Premature triggering. Know nothing about that...

*It must be an ex Uni scope you're using if it gets so easily "triggered" by barely measurable microaggressions!* 😅😅