I want to briefly go over how to use an oscilloscope.
When I was in senior design in college, we had all of our oscilloscopes
in the lab and the professor did not like the fact that we just hit auto
and hoped that it found the signal and so we put a piece of tape on it
and despite being very angry at the time, I've learned a lot of good stuff.
So I want to share like the basics of how to use an oscilloscope.
One of the fun things about oscilloscopes is they're all different.
Even though I have this one right here and I'll be pointing at different things.
It's more important to understand the concepts and then find it on your own
oscilloscope because it's almost certainly completely different
and where it is, probably even how its labeled.
Right now, I have my arbitrary waveform generator giving me a 1000 Hertz
(one kilohertz) signal to the oscilloscope just to give you an example.
So first things first,
Let's mess everything up.
Have it make absolutely no sense.
That auto button that I talked about on this one, you just hit auto here click a couple times and bam! right there.
You get a beautiful sine wave. You look down here voltage peak to peak
5.2 ish volts which according to my waveform generators, off by a quarter volt.
But also the frequency is spot-on with one kilohertz.
That's fantastic.
Now, if you're in a rush near here
You know what you're doing, there's no problem using the auto.
But you can't become dependent on it because sometimes there will be signals
That you just, it can't figure out.
It doesn't know what to look like.
And if you don't have a good understanding of what you're looking at,
Then you're gonna miss some very important stuff.
So one of the first things that you want to look at is the width here.
So right now, I can see right here that each division is 200 microseconds.
So there's a box right here. From here to here, is 200 microseconds.
Now, I can change the scale of that. Oh, even I'm screwing this up.
That's the vertical scale.
I can change the horizontal scale.
So now it says 500 microseconds.
Going back, now that's 100 microseconds.
So you can see as you go in and out, it gives you a good idea of what you are looking at.
And not only can you make it wider and skinnier, you can also slide it back and forth.
So if you have perhaps something a square wave that you have a trigger and it pops over here
Then, you have absolutely nothing for a while
And then it pops up again and you want to see that later.
You can make it so it triggers and then you slide over to look at the signal that you want to see.
So that's really great for doing like digital logic and things such as that.
So that is a very important thing, is the width and you need to pay attention to where you are
And noticing right now that I'm at one millisecond per division.
That just gives me a general sense of how fast of a signal am I looking for.
If I'm looking for a 1,000 Hertz signal and it looks like this, with one millisecond, all right I'm good.
But if I see something like this and I noticed that each division is closer to 50 milliseconds
I might actually be looking at some 60 Hertz or something and not even notice it.
So that's why it's important to pay attention to what you're doing.
So again, every single oscilloscope will have that ability to change the scale.
And if you were looking for a higher frequency noise, you crank that up right now,
This one can get up to one nanosecond, you start to get some ugliness there.
But it's good for when you're looking for higher frequency stuff obviously one kilohertz.
Isn't that high of a frequency.
Actually, I'll jump over and show you a square wave.
And this is where it comes in really handy because right now you can barely see
the vertical portion of that square wave.
But let's line that up with the center and then zoom in pretty good
And you think okay, that's almost an instantaneous.
Rise and voltage from zero to five but as you get closer and closer you notice
There's a rise time right there, so right now it's five nanoseconds per division.
So you can kind of look at it and visually you can tell takes about ten nanoseconds
To go from zero to five volts.
So that's a great thing to use with your oscilloscope
And is actually a feature that you just don't get with one of those digital logic analyzers.
It just notices oh, hey you have a high, you have a low
And can't see any overshoot or undershoot or that rise time.
So that is one of the times you will need to use the face
So you notice that I slid that over to get it in the center and then change the width
So now it's 2 nanoseconds per division.
So that is how you find things and again if you just hit auto, you can't see those sorts of things.
You can barely see the vertical lines at all.
So let's go back to the sine wave and let's talk about the vertical right now.
So right now, I'm at 5 volts peak-to-peak and again a little bit over 5 volts there.
I can change the shift and this is actually very helpful when I'm using both channels
Because I might want one channel to be right above the other so I can compare them.
So I can literally just shift it like this and then I'll shift the other one.
I don't have this second channel plugged in right now.
And then I can compare them side to side.
But you can on this one, you just press it and it puts it back down so there's no shift.
So as I'm changing this vertical scale, you can actually see down here in the corner
And again, it'll almost certainly be somewhere different on whatever oscilloscope you're using but it's showing one volt.
So now each vertical box is 1 volt. So you count 1 2 3 4 and change on the top and bottom.
So yeah, it makes sense. It looks like five volts.
One common mistake with this is using your probe.
Now, I'm not sure if you can see on it but on this there's actually a slider.
So, X10 X1. If I slide it to X1, it suddenly gets a lot different.
And it thinks now that my signal is basically 50 volts peak-to-peak and it's 10 volts per box.
So you need to be careful that you have the right probe and it's on the right setting
Or else you're gonna be really confused about what you are getting out of your oscilloscope.
So let's get this back to a more reasonable place.
Okay, so those that's really the basics.
If you know those two things, you can do a lot of things with the oscilloscope.
But let's go over a couple other things that might be important for you
And I think one of the bigger ones is the trigger.
So right now everything's lined up and it looks great.
Okay and it's doing that automatically.
And on this one, I can actually see right here the mode is on auto.
But if I want to manually control the trigger,
I can move it up and you'll notice
So I go up, it's changing because what it's doing is every time it sees a voltage that hits that level
It says, okay there's a signal I want to see and this makes sense
Because if you have a lot of like a really noisy signal down there, you want to ignore that.
You don't want it causing your oscilloscope to say oh, there's something there when it's really just noise.
So you can control your trigger.
But the problem is if you put it too high, then it doesn't know what's going on.
And it can't really latch on to it.
So you need to control your trigger, make sure that it's at an appropriate level for your signal.
And frankly most the time, it's automatically going to be where you want it to be.
So don't worry about that too much.
But if for some reason your signal is going wild all over the screen like that
Most likely it's a trigger issue that you need to fix.
So let's get this trigger back down to zero. Nice.
So one final thing.
Now you already basically know how to find a signal. You can go in and out both vertically and horizontally.
But it's not very helpful if you're just looking at it and trying to count the division.
Sometimes you want more precision than that.
And again, almost every single oscilloscope will have this feature but it will be different.
And depending on how expensive it is it'll be better and you'll have more features.
But you can actually do measurements.
Click on this one. You push this button over here, and it has horizontal. So it shows you the period, frequency,
rise time, fall time, pulse width, things like that.
So if I want to, let's look at the fall time, I go down I say fall time all right, and it says 286 microseconds.
You can also see down here the frequency is 1 kilohertz, a rise time 2 point, again almost the exact same
As a fall time and then your average which shows a little bit of a voltage offset here.
So using that measurement, you can get a really good idea, again, the most important thing with the oscilloscope.
Just take your time. Don't freak out.
Again, you notice that I didn't use the majority of these buttons.
And unless you're doing more complicated things, you don't need the majority of the buttons on the oscilloscope
To really understand what you're doing and to get good results out of it.
So hopefully that helps you understand kind of the basic things that you need to know
When you're looking at your oscilloscope and next time you want just get on it.
Just play with it. Relax. Take your time.
And make sure you have a good waveform generator or some sort of input that you know what you want.
And then you can find it.
And with time, it'll become second nature and it'll be great.
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As it is, thank you very much.