Frequently Asked Questions. International Shipping Info. Send Email. Mon-Fri, 9am to 12pm and 1pm to 5pm U. Mountain Time:. Have you ever found yourself troubleshooting a circuit, needing more information than a simple multimeter can provide? If you need to uncover information like frequency, noise, amplitude, or any other characteristic that might change over time, you need an oscilloscope!
O-scopes are an important tool in any electrical engineer's lab. They allow you to see electric signals as they vary over time, which can be critical in diagnosing why your timer circuit isn't blinking correctly, or why your noise maker isn't reaching maximum annoyance levels. The Digilent Analog Discovery 2 is a USB oscilloscope and multi-function instrument that allows users to measure, control, an….
An oscilloscope is an awesome tool to have around the shop. Unfortunately, most scopes take up quite a bit of bench space and…. This tutorial aims to introduce the concepts, terminology, and control systems of oscilloscopes.
It's broken down into the following sections:. We'll be using the Gratten GACAL -- a handy, mid-level, digital oscilloscope -- as the basis for our scope discussion. Other o-scopes may look different, but they should all share a similar set of control and interface mechanisms. Before continuing with this tutorial, you should be familiar with the concepts below. Check out the tutorial if you want to learn more!
The main purpose of an oscilloscope is to graph an electrical signal as it varies over time. Most scopes produce a two-dimensional graph with time on the x-axis and voltage on the y-axis.
An example of an oscilloscope display. A signal the yellow sine wave in this case is graphed on a horizontal time axis and a vertical voltage axis.
Controls surrounding the scope's screen allow you to adjust the scale of the graph, both vertically and horizontally -- allowing you to zoom in and out on a signal.
There are also controls to set the trigger on the scope, which helps focus and stabilize the display.
In addition to those fundamental features, many scopes have measurement tools, which help to quickly quantify frequency, amplitude, and other waveform characteristics. In general a scope can measure both time-based and voltage-based characteristics:.
Learning how to use an oscilloscope means being introduced to an entire lexicon of terms. On this page we'll introduce some of the important o-scope buzzwords you should be familiar with before turning one on. Some scopes are better than others.
These characteristics help define how well you might expect a scope to perform:. Understanding these characteristics, you should be able to pick out an oscilloscope that'll best fit your needs. But you still have to know how to use it While no scopes are created exactly equal, they should all share a few similarities that make them function similarly.
On this page we'll discuss a few of the more common systems of an oscilloscope: the display , horizontal , vertical , trigger , and inputs. Every oscilloscope display should be criss-crossed with horizontal and vertical lines called divisions.
The scale of those divisions are modified with the horizontal and vertical systems. Generally, scopes will feature around vertical voltage divisions, and horizontal seconds divisions.
Older scopes especially those of the analog variety usually feature a simple, monochrome display, though the intensity of the wave may vary. More modern scopes feature multicolor LCD screens, which are a great help in showing more than one waveform at a time. Many scope displays are situated next to a set of about five buttons -- either to the side or below the display. These buttons can be used to navigate menus and control settings of the scope.
The vertical section of the scope controls the voltage scale on the display. The more critical volts per division knob allows you to set the vertical scale on the screen.
Rotating the knob clockwise will decrease the scale, and counter-clockwise will increase. The position knob controls the vertical offset of the waveform on the screen. Rotate the knob clockwise, and the wave will move down, counter-clockwise will move it up the display.
You can use the position knob to offset part of a waveform off the screen. If you had a 5V square wave, but only cared about how much it was ringing on the edges, you could zoom in on the rising edge using both knobs.
The horizontal section of the scope controls the time scale on the screen. Rotate counter-clockwise to increase the time scale, and show a longer amount of time on the screen. Using the GA as an example again, the display has 14 horizontal divisions, and can show anywhere between 2nS and 50s per division.
So zoomed all the way in on the horizontal scale, the scope can show 28nS of a waveform, and zoomed way out it can show a signal as it changes over seconds. The position knob can move your waveform to the right or left of the display, adjusting the horizontal offset. Using the horizontal system, you can adjust how many periods of a waveform you want to see.
You can zoom out, and show multiple peaks and troughs of a signal:. The trigger section is devoted to stabilizing and focusing the oscilloscope. If your waveform is periodic , the trigger can be manipulated to keep the display static and unflinching. A poorly triggered wave will produce seizure-inducing sweeping waves like this:. The trigger section of a scope is usually comprised of a level knob and a set of buttons to select the source and type of the trigger.
The level knob can be twisted to set a trigger to a specific voltage point. A series of buttons and screen menus make up the rest of the trigger system. Their main purpose is to select the trigger source and mode. There are a variety of trigger types , which manipulate how the trigger is activated:. You can also usually select a triggering mode , which, in effect, tells the scope how strongly you feel about your trigger. Normal mode will only draw your wave if it sees the specified trigger.
And single mode looks for your specified trigger, when it sees it it will draw your wave then stop. An oscilloscope is only good if you can actually connect it to a signal, and for that you need probes. Probes are single-input devices that route a signal from your circuit to the scope. They have a sharp tip which probes into a point on your circuit. The tip can also be equipped with hooks, tweezers or clips to make latching onto a circuit easier.
Every probe also includes a ground clip , which should be secured safely to a common ground point on the circuit under test. There are a variety of probe types out there, the most common of which is the passive probe , included with most scopes.
Attenuating probes have a large resistance intentionally built-in and shunted by a small capacitor , which helps to minimize the effect that a long cable might have on loading your circuit. In series with the input impedance of a scope, this attenuated probe will create a voltage divider between your signal and the scope input.
These probes are commonly called 10X attenuated probes. Many probes include a switch to select between 10X and 1X no attenuation. Attenuated probes are great for improving accuracy at high frequencies, but they will also reduce the amplitude of your signal. Beyond the passive attenuated probe, there are a variety of other probes out there. Active probes are powered probes they require a separate power source , which can amplify your signal or even pre-process it before it get to your scope.
While most probes are designed to measure voltage, there are probes designed to measure AC or DC current. Current probes are unique because they often clamp around a wire, never actually making contact with the circuit.
The infinite variety of signals out there means you'll never operate an oscilloscope the same way twice. But there are some steps you can count on performing just about every time you test a circuit. On this page we'll show an example signal, and the steps required to measure it. First off, you'll need to select a probe. For most signals, the simple passive probe included with your scope will work perfectly fine.
Next, before connecting it to your scope, set the attenuation on your probe. If you're trying to measure a very low-voltage signal though, you may need to use 1X.
Connect your probe to the first channel on your scope, and turn it on. Have some patience here, some scopes take as long to boot up as an old PC. When the scope boots up you should see the divisions, scale, and a noisy, flat line of a waveform. The screen should also show previously set values for time and volts per div. Ignoring those scales for now, make these adjustments to put your scope into a standard setup :. For help making these adjustments, consult your scope's user's manual as an example, here's the GACAL manual.
Let's connect that channel up to a meaningful signal. Most scopes will have a built-in frequency generator that emits a reliable, set-frequency wave -- on the GACAL there is a 1kHz square wave output at the bottom-right of the front panel. The frequency generator output has two separate conductors -- one for the signal and one for ground.
Connect your probe's ground clip to the ground, and the probe tip to the signal output. As soon as you connect both parts of the probe, you should see a signal begin to dance around your screen. Try fiddling with the horizontal and vertical system knobs to maneuver the waveform around the screen.
Rotating the scale knobs clockwise will "zoom into" your waveform, and counter-clockwise zooms out. You can also use the position knob to further locate your waveform.
If your wave is still unstable, try rotating the trigger position knob. Make sure the trigger isn't higher than the tallest peak of your waveform. By default, the trigger type should be set to edge, which is usually a good choice for square waves like this. If your probe is set to 10X, and you don't have a perfectly square waveform as shown above, you may need to compensate your probe.
Most probes have a recessed screw head, which you can rotate to adjust the shunt capacitance of the probe. Try using a small screwdriver to rotate this trimmer, and look at what happens to the waveform. Adjust the trimming cap on the probe handle until you have a straight-edged square wave. Compensation is only necessary if your probe is attenuated e. Once you've compensated your probe, it's time to measure a real signal! Multimeter can directly measure resistance of a circuit.
Using a CRO as a voltmeter. A CRO cathode ray oscilloscope can be used to measure potential differences, and to see how they vary. But, today, one would use a digital voltmeter for any serious measurements.
Oscilloscope shows us the peak to peak amplitude of the signal and also shows us the frequency of the signal One advantage of using an oscilloscope is its capability of monitoring the amount of AC ripple voltage riding the DC voltage; this makes an oscilloscope perfect for troubleshooting DC power supplies with.
Bandwidth -- Oscilloscopes are most commonly used to measure waveforms which have a defined frequency. No scope is perfect though: they all have limits as to how fast they can see a signal change. The bandwidth of a scope specifies the range of frequencies it can reliably measure.
Overload protection prevents damage to both the meter and the circuit, while protecting the user. Special high-energy fuses provide extra protection for user and meter during current measurements and overloads. A 10X oscilloscope refers to a probe with an integrated attenuator that delivers an attenuation of This allows the circuits' impedance to be enhanced by a factor of While the 10X probe is attenuating the signal, it can also reduce the signal entering the oscilloscope. Common Oscilloscope Applications.
Oscilloscopes are used for a number of applications and in a number of different industries. Some examples of professionals who use oscilloscopes are automotive mechanics, medical researchers, television repair technicians, and physicists. While oscilloscopes cannot measure electrical current directly, that task requires a multi-meter, an oscilloscope can indirectly measure an electrical current.
Doing so requires the use of resistors and a knowledge of Ohm's Law, but the process is not difficult. Most oscilloscopes can only directly measure voltage , not current. One way to measure AC current with an oscilloscope is to measure the voltage dropped across a shunt resistor. Secondly, oscilloscopes are precision devices.
They need to undergo rigorous quality control to ensure they live up to expected standards. This further increases costs. In the end the precision, bandwidth and limited production quantities that drive up prices. Definition: The cathode ray oscilloscope CRO is a type of electrical instrument which is used for showing the measurement and analysis of waveforms and others electronic and electrical phenomenon. It is a very fast X-Y plotter shows the input signal versus another signal or versus time.
Count the number of horizontal divisions from one high point to the next i. You may measure the gain or amplification of a circuit using both channel one and channel two of the oscilloscope.
You will monitor the input signal with one channel and the output signal with the other. The difference between the amplitudes of these two signals indicates the gain.
Originally Answered: What is meant by trace of oscilloscope? Trace is the tract, the path made by the moving electron beam in the CRO. The default trace is a horizontal line. Dual trace means the CRO is able to display two independent waveforms simultaneously.
The most common type of probe with a built in attenuator gives an attenuation of ten, and it is known as a X10 oscilloscope probe. The 10X scope probe uses a series resistor 9 M Ohms to provide a 10 : 1 attenuation when it is used with the 1 M Ohm input impedance of the scope itself. The oscilloscope is basically a graph-displaying device — it draws a graph of an electrical signal see Figure 1.
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