Hi just a quick oscilloscope tip video. Now modern digital scopes are called very handy because they've got single shot capture capability and allows you to capture multiple waveforms and display them on the screen. and of course get time correlated information of how they switch uh between one another like this and then you could, uh, go in there and look at the timing differences and uh, count your divisions and use your cursors and do all sorts of other measurements. and of course, uh, modern scopes.

I recommend like a four channel scope these days because well, even entry level ones like sub 400 dollar scopes there you can get like four channel ones. So yeah, it's handy to be able to look at multiple signals. but the problem is modern electronics unfortunately is all this modern surface mount rubbish. Of course the problem with that is if you want to say probe two signals at once, you've got to use one hand to hold both probes like this and hold your tongue at the right angle so that you've got, uh, the other hand free to operate the scope or you know, power the unit up or do whatever.

and of course you can really slip and come. a guts are and you can short things out and you know generally ruin your day. not to mention if you want to measure more than two signals. So what do you do if you want to measure more than one signal and get the time correlation between them but you've only got one hand to do it and you don't have like any ready access points to actually, uh, use your easy hook for example to get in there and like through and actually clip onto there.

so you've got one hand free like that and the other and bingo. Now we can do it. What if you need to get in there with both of these points and oh, just dung at the right angle? Well now of course you could actually get in there and like, uh, you know, solder a little, uh, wire up, uh from whatever part that you wanted to measure whatever signal, uh, test point that you want to measure, but you know it might be like a tiny pin on a little quad flat pack or a little O 402 component or something like that. You know, like you're just really annoying stuff and you might have to physically take the board out or bring your soldering iron over to it.

Or you know, whatever you need to do that just can be like a really annoying solution. You might end up shorting things out, or you know, ruining your board or doing whatever. You just want to probe the damn thing. You know you just want to take a couple of seconds to probe it.

So how can you probe two signals with only one hand? Well, I've got a tip for you. Get it? I'm here all week now. The first thing to do is find like a readily available reference waveform point that you can trigger off. Uh, for example, if you're trying to like re-power uh, this product with the main switch under here for example, then like a power supply can often be a good thing to hook on to.

So a 3.3 volt digital power supply here. Bingo! Look at these. We've got through hole caps up here so we can actually clip onto the output voltage of the 3.3 volt rail. No worries.

So in this case we set up our scope for uh, triggering off a Channel one. You know, positive going edge, all that sort of stuff. So it's all happening. We're good to go.

So we now have a rising edge reference point which will be our power supply that we can trigger off and then get time correlation between any other signals we want to probe. Now of course we can just probe them one at a time and do a single shot capture like this for example. and we get this waveform here. and then we do a another one and then we single shot capture again and then we probe another point here.

Okay, but we can see those waveforms. but the problem is of course that we're not going to be able to see the time correlation between them because we have to trigger from the waveform under test. we don't have a like a separate reference that we can actually compare the two right. So if we take as channel 1 for example and trigger off our 3.3 volt a rail here, Bingo! We now have a reference waveform on Channel one that always triggers at the same point.

So now we can use Channel two to actually probe our two other signals. But how do we measure two signals with one channel? Aha, This is where a really useful feature of most modern scopes comes in. And that's reference waveforms. So in this 1000x series, Uh, keysight.

we actually go into analyze up here and our features. And Bingo! We've got two reference waveforms. Some scopes might have like five or ten reference waveforms or something like that, but two Very handy. So we can actually choose our reference waveform like that and this is our feature.

We enable that and then we can save and clear waveforms that we actually capture. See, I've got one there previously, so let's clear any existing reference waveforms there. and now we're ready to probe with our second channel. our first signal that we want to capture.

All right, I've probed my first tricky point down there and I've still got one hand free and I'm not going to accidentally short anything out. Let's go single shot capture. Let's power it on and you'll see that. Bingo and you'll see that we have a triggered offer Channel one here, which is the 3.3 volt rail and you can see that the signal that we've actually measured immediately went uh high like that.

although you can of course zoom into that and actually see, you can just go zero like that. Zoom in and see. Yep, they did actually ramp up at the same time. So we want to actually select the source.

Now that we want to save, we want to save Channel two And Bingo! we just gave save to R1 like that and you'll notice that's changed color up there and our reference waveform has now been stored. So what we can then do is simply move our waveform up here and we can capture another one. Let's do it again. So this reference waveform here will stay there.

even if we go single shot capture again, it's going to stay there as our reference as long as you don't touch the time base or anything else. Now we can probe and capture the second signal. Now let's probe the second signal. It looks like the same spot, but it's actually not.

It's like one or two millimeters apart. That's what makes it really tricky to probe both of these points at the same time with one scope probe. Especially when you've got like everything in the way like heatsink and crystal here there are. This is actually a real genuine example.

I tried to troubleshoot these two signals actually repairing this speaker and I wanted to do this. I can't like. hold both of the probes in there at the same time, not short anything out, not slip and you know be able To operate the scope and the power switch at the same time. So yeah, this is really handy.

So anyway, we're probing that and let's switch it back on again. Here we go and bingo that. Trust me, that is a different point. I.

I know I probably could have chosen a better example than this, but trust me, these are two different signals even though they're doing exactly the same thing. So you have to watch my previous video to know. But trust me, if the signal was different, then you'd be able to see. Let's say it went uh high here for example.

Then you'd be able to see that it went high like, you know, 250 or 300 milliseconds like before this one did. But this is helpful because in this particular case, I've actually, uh, determined that these signals are that match. They do the same thing even though this is two separate signal points. So this, actually, even though they look identical, this actually gives me valuable troubleshooting information about what's happening in my circuit.

They don't have to be different. They could be the same. That could be the result that you're interested in. And just to show you that they are actually different, we can actually go over to here and we can see a subtle difference in timing between them if we zoom in like that.

aha look, this one is doing some sort of like analogy. ramp up, funny business, back down, and then back up. Whereas the other signal we were measuring is more digitally. so you can see um, well, this is actually occurring.

You know, a millisecond or two milliseconds before the other one, so they seem similar on the surface by looking at them. But we can actually go in there and see subtle differences between timings and this is not the best example of course. Or we can measure another signal here. and then we can see Ah-ha.

Well, if you zoom right in there, you can see this one is doing something there. So we can go in and actually zoom in and take a look what's going on there so you can see that something happened there. Whoa, We don't. Unfortunately, our memory depth here is just not.

We can see something happen there at, you know what, five microseconds or something like that. but there's obviously a little pulse in there before this thing happens. So this allows us to really like troubleshoot differences between signals. And of course, we can use multiple reference waveforms.

This scope has two, and of course we could actually, uh, save that. Oh, push the wrong button. I was gonna say we could. I should have actually changed that to reference waveform two.

Anyway, we could change that to another reference there. and we could have multiple references on the screen. and you can do this for multiple Uh signals. So even though we've got our four channel uh scope here which is more than capable of like viewing in this particular case are three signals at Uh, the a correlation between three separate Uh signals, the fact that we've got all this surface mount stuff down here that's really difficult to probe and hold the probes on reference waveforms can just be a really handy way to actually do that.

So yes, I know there's ways you can get like these big arm things to like hold your probes at certain points and stuff like that, but as you can see, don't really have room to do that and it gets like really messy. Um, so this is just a quick and easy method using reference waveforms Just to you know, get yourself out of trouble and not have to go in there and solder stuff onto you a board because you might have to like to do that. you might have to disassemble it or you know or something like that. So anyway, I hope you found that tip useful.

and if you did, please give it a big thumbs up. And as always, discuss down below, catch you next time.