<< Chapter < Page Chapter >> Page >
Explains what an oscilloscope is and how one is used.

What is an oscilloscope?

An oscilloscope is a device that measures and displays voltages as a time versus voltage graph. The voltage difference between the positive and negative probe leads is measured, buffered, and displayed on the screen as a continuous curve.Because the quality of the scope affects how finely it can resolve changes in time and voltage, very sensitive or small signals may not be measurable with all oscilloscopes.For most educational purposes, however, an average oscilloscope will display the signal well enough.

Oscilloscopes are generally used to see if a circuit is performing as expected, but oscilloscopes are also useful for comparing different signals to each other.Comparisons and absolute measurements are made by comparing the signal to the graph on the display.

Oscilloscope controls

The most common oscilloscope controls are for amplitude, frequency, triggering, and signal comparison.

The amplitude adjustment of an oscilloscope controls how tall a given voltage will appear on the screen. Usually the screen will be marked off with horizontal lines to indicate the signal's voltage.The absolute voltage per horizontal line is adjustable. Thus, if the amplitude is set to 1V/ then each block a signal is tall is 1 V.The purpose of this adjustment is that you can see a very large or a very small signal on the same screen.

The time adjustment of an oscilloscope is how much time will a certain distance across the screen represent. The vertical lines most oscilloscopes have are the standard distanceand the knob or screen indicator will describe how time that distance represents. The purpose of this adjustment is to be able to see a very quickly changing or a slowly changing signal on the same screen.

Triggering refers to the means by which the oscilloscope selects the exact moment to display on the screen. Because electrical signals often change far faster than a human being could observe them, it is necessary to onlydisplay a small sampling of the signal. If a signal has a repeating pattern, then the pattern will be repeatedly shown on the screen so that it can be viewed continuously.If the signal does not have a regular pattern then the oscilloscope will have trouble choosing the best moment to refresh the display. In this case, you will need to set up a trigger so that the oscilloscope can freeze the screen at the right time.Trigger controls allow for conditions such as an upward edge of a signal, a voltage glitch, or a voltage threshold. Trigger controls can also allow for the display refresh to occur after a time delay from the time of the trigger event.You should adjust thee triggering of an oscilloscope if the signal seems to be sliding left and right on the display or changing too fast to be seen.

Because many oscilloscopes allow multiple signals to be compared at the same time, it is necessary to have controls to handle the display of these signals. The most basic control is the ability to turn off the channels that are not in use to avoid useless cluttering of the display screen.Oscilloscopes also allow for two different channels to be compared by displaying the additive difference between them instead of the signals individually. Usually different signals can also be displayed with different amplitude adjustments, but they require the same frequency adjustment.Finally, if special triggering conditions are used, the trigger system will ask for which channel should trigger the display.

Hazards to avoid

Triggering is probably the trickiest skill to acquire. Generally, adjusting the voltage level for the default trigger will fix most triggering problems on analog signals.For more complicated observations, the most useful tool in triggering is a time delay. While exact moment of the signal that is interesting to you may not be easy to trigger on,often this moment occurs at a fixed time offset from an event that is easy to trigger on. Try finding a signal transition or voltage threshold that stabilizes the display,then adjusting the time delay to observe your signal.

It is important to ensure that both probes the positive and negative leads of the probe are attached to the device. Usually the negative lead can attach to the ground plane of the device,

Oscilloscope probes must be attached to the signal being measured and to the ground plane of the circuit too.Noise is introduced if both probes are not properly attached to the device.

It is also important to note that the probe itself has a 1M ohm resistance. This means that from most digital circuits, the probe will not draw any significant power.However if you are trying to measure voltage from a node between two 10M ohm resistors, it would drop the voltage by about half! The lesson is that you will sometimes need to be aware of how the probe affects what you are measuring. Finally the capacitance and inductance of the probe itself can affect finely tuned analog signals.Very high speed signals (approaching 100MHz) can be very difficult to measure with an oscilloscope.

Questions & Answers

how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
Maciej
Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
AMJAD
what is system testing
AMJAD
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
can nanotechnology change the direction of the face of the world
Prasenjit Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Good
Berger describes sociologists as concerned with
Mueller Reply
Got questions? Join the online conversation and get instant answers!
QuizOver.com Reply

Get the best Algebra and trigonometry course in your pocket!





Source:  OpenStax, Microcontroller and embedded systems laboratory. OpenStax CNX. Feb 11, 2006 Download for free at http://cnx.org/content/col10215/1.29
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Microcontroller and embedded systems laboratory' conversation and receive update notifications?

Ask