 In this video, I'm just going to be going over a quick once over on what an oscilloscope is They're very very cool. We're gonna call them scopes from now on because that's what the cool kids call them and JJ says they are dynamite Now you're not going to end up using a scope that much out in the field There's only been a couple times in my whole careers in electrician having used a scope in the field That's not to say you won't but the chances are rare what they are excellent for though is for us in School to analyze waveforms and they can tell us a lot So let's take a look at a couple of the waveforms. We're going to be dealing with So here we go. I've got myself a sine wave. So I've got my AC sine wave. That's jiggity jiggity jiggity there. I've got a DC Typically DC square tooth I've got a typical DC triangular and then I have a sawtooth voltage here Now the thing is with the AC waveform we can look at this and we're talking about frequency and cycles Cycle is from where a waveform starts to where it repeats itself Well an AC it starts here and it starts to repeat itself there. So that is a full cycle DC however is a little different if we look at it Starting right here. This guy goes along goes up over and then he repeats himself up over and then repeats itself This being a DC waveform means it will either be all positive or all negative So it'll either sit above or below the x-axis. It's not a Alternating waveform that has a positive and a negative alternation like this one here at the sine wave Same thing goes for this triangular It's going to start here and that is a cycle there and that is a cycle there That's important when we get to frequencies same thing with the sawtooth starts here begins to repeat itself and away We go. So that is our DC waveforms Now there's a lot too in a oscilloscope, which I'm going to let you guys go through in notes that I'm attaching to this But let's talk a little bit about the probes here and it's not these kind of probes that we're thinking about here We're going to be talking about These probes here. So these probes are what we use to attach to the circuit They are made out of a coaxial cable That would be important to know because what they take care of is stray voltages So and we want to clean up our sine wave when we're looking at sine waves They want to look nice and clean and sometimes the induced voltage around can dirty that waveform up So what the coaxial cable does is it's shielded and it gets rid of all the unwanted noise So that we get as crisp and clear a waveform as we possibly can Now when we connect these probes we have two channels we have channel one and channel two and again Just like your TV. It's a coax connection there. This means we can read two different wave forms Which is very useful when we get to AC because we can start looking at what happens when we have inductive circuits and capacitive circuits Which I'm not gonna get too much into right now. You can watch the videos on capacitance and inductance on your own But we have two channels here. Sometimes they're called channel A and B We're gonna call them channel one and channel two now. We have this thing here the volts per division We'll talk about that. It has a lot to do with this little fellow right here the screen So that's channel A's volts per division and channel B's volts per division Per division or one and two and then we have our time per division So that helps us determine what the period is and then from period we can determine frequency Now when it comes to calibrating the probes generally what we do is we send them out, but on some oscilloscopes, there'll be a calibration knob So what you can do is take your probe and attach it to that knob and you'll see if it is correctly compensated You're gonna see a nice square-tooth wave like that if it is under compensated It's got a bit of a hook to it and if it's over compensated. It's the other way here We got a little nub or a little rise there So then you would just adjust there's a little dial on your probe You would adjust that to get it looking more like that But for the most part really just let your instructor know and they will send out and get a better probe for you Now when we are hooking up oscilloscopes, there is a danger of a short circuit when we've got this thing connected Let's take a look here. I've got a line in a neutral. So let's say it's 120 volts circuit Our neutral is grounded as neutral should be I take my scope and I connect it I put my probe on one side and I take my ground clip and I attach it to the other side The ground here is gonna give me a zero reference point. It's not just grounding for safety sakes It's just giving me reference So it's the probe is reading from this point to this point here So it's reading like a visual voltmeter going across there like that Now that's a proper connection because current can go through here and go down there And I can read the this scope will have a high impedance into it So it won't allow current to flow through it now. Let's take a look what happens if we hook it up the wrong way With it hooked up the wrong way I have the probe on this side now and the ground clip on this side Current here is just gonna go and go right to ground and it's gonna blow a fuse and that's not a good thing Is it and you're not gonna be able to read anything? I've seen this happen in labs before and there's only one way to get around that is you either have to take all your circuits apart and find out Which one has your grounded side or you can use an isolation transformer over here? We have our isolation transformer. So this is going off to the oscilloscope We have the primary side is grounded if you don't understand how transformers work Make sure you watch the videos on transformers, but we have this side is grounded this secondary side has no ground to it So it is completely I said it's still protected from the primary side on this ground, but this side We have no ground so we don't have to worry about that one circuit floating through and going down to ground and causing a short So that's how we get rid of it is this isolation transformer Now when we're looking at the scope We're gonna be looking at its screen and its screen is what tells us gives us the visual representation of what we're looking for Also known as a graticule on analog scopes. It's a phosphor screen, but for the most part we'll be using digital scopes it has one two three four five six seven eight nine ten divisions across and One two three four five six seven eight divisions up We have an x-axis and a y-axis Along the x-axis is where we determine our Frequency or our period and it is along the y-axis that will determine The amplitude of the waveform So let's see what I mean. Let's do a couple examples here All right, let's say that this guy here is set to five volts per division Which means if we're using channel one we'd have this guy here dialed up till it hits five volts per division Which would show on the bottom of this guy Now we've got that at five volts per division. So let's go back and take a look at our waveform This is five volts per division. I've got a waveform here. It starts here goes along there Watch it start it here goes below then above then below it continues on and on and on now If we are reading the actual size of the waveform of the peak of the waveform I see that I've got one full division two full divisions. I've got two full divisions and FYI each division is a centimeter So sometimes you'll see it as five volts per centimeter. Anyways, I've got five volts per division If it has got a times one probe on it So I should have mentioned that when we talked about probes before but your probe can be a times one or a times ten Meaning that it'll be ten times the size when you actually read it through I'll look over that in a second here times one two times five volts per division gives me ten volts with a times one probe That's ten volts peak from there You can determine what your RMS value is by taking peak times point seven or seven easy enough If your probe was set to times ten again We go two full divisions times five volts per division gives me ten times ten for the probe So that would mean that I am reading one hundred volts not the ten volts So really pay attention to your probe and is it if it's set to times one or times ten Now you notice these little hash marks here as well Not all waveforms are going to be exactly full divisions They might come up halfway through a division or whatever each hash mark here is point two So it'd be point two point four point six point eight. So if you're taking it and you measure across and it's at two point six Divisions you go two point six times five to get your volts. That's how you determine that out Now let's talk about the frequency We talked about this volts per division now We're going to set the time for division and we're going to set that to a certain amount of seconds or milliseconds per division Now let's look back at here. We already determined that this guy with the times one probe We're looking at ten volts peak now. We want to work out what the period and the frequency is Well, let's take one alternation I got one full division two full divisions three full divisions for full divisions for an alternation I remember that four divisions for an alternation will mean eight divisions for a full cycle Pay attention to that because we deal with full cycles not just with alternations. So we're going to go 16 milliseconds and we set the times per division at two milliseconds per division Well, sorry, we've got eight full divisions We're going to multiply it two times eight So we're going to end up with sixteen milliseconds And I had to tell you before that we had this thing set to two milliseconds per division on the times per division dial Sixteen milliseconds that would be your period from that That's how long it takes from this guy to start till it starts to repeat itself And if we want to learn about frequency or what the frequency is all we have to do is Invert that so we take sixteen milliseconds or point zero one six seconds and we flip it one over that We end up with sixty ish Hertz. I say sixty ish because it's actually gonna be a little less not but we'll talk about that later It's just a rounding issue at this point Now there's something else that we're going to use in a oscilloscope for nuts called phase displacement It allows us to look at different circuits and analyze their phase displacement I'm not going to get too much into that go to the AC principles videos and you can learn about phase displacement there I'm just going to show you how we measure for phase displacement. So first off. I have these two waveforms I have a blue waveform and I have a red waveform Now the blue waveform crosses the x-axis first then the red waveform crosses So in this case, I will say that blue leads Red All right now we're gonna also figure out by how many degrees does blue read lead red So I look at this and I say okay one two three four five six seven eight nine ten divisions Sorry nine divisions. Is that right? Yes one two three four five six seven eight Nine divisions for an alternation. Well, we know that one alternation contains a hundred and eighty degrees So a hundred and eighty divided by nine gives me twenty degrees per division So we get twenty forty sixty eighty one hundred hundred twenty hundred forty hundred sixty hundred eighty Now we see that we have one full division between the two waveforms Well, if we know that each division is worth twenty degrees We can say that blue leads red by twenty degrees And that's how we calculate out phase displacement You look for which waveform crosses the x-axis first then you determine how many degrees per division off of one alternation Now both waveforms will have the same frequency because you're reading them off the same power supply So you can use either waveform. I just use the blue same thing I can use the red and still seeing that there was nine full divisions 180 degrees per 20 degrees per division then I end up with one Division between the two and I get 20 degrees per division And that's kind of the basics of what we're going to be dealing with with scopes when we get into the lab We'll fool around a lot more with those