Oscilloscope questions?

[pfelectronicstechnician]

I'm learning about using Oscilloscope, are they as complicated as they seem or I am just green?
Anyway if I have Oscilloscope that is set to display 5 volts per division vertically and 5 micro seconds per division horizontally, what is the frequency? I think its 1,000Hz or 100Hz?
Also in order to center a waveform on an Oscilloscope which control do you use, its the vertical positioning control right? Thanks for the help.

 

[Sceadwian]

It's just a tool... It's not complicated at all if you know how to use it.
The volts per division has no reflection on your question.
The time constant of a 5u sine wave is 200Khz... a 1Khz wave will have a time constant of 1ms not 1us.

Although you may think you have provided enough information you have not, at least to understand what it is you're trying to do.

 

[pfelectronicstechnician]

The oscilloscope screen shown is set to display 5 volts
per division vertically and 5 microseconds per division horizontally. What’s the frequency of this waveform?
This is the full question. Thanks again for the help.

 

[Steaphany]

The oscilloscope screen shown is set to display... 5 microseconds per division horizontally. What’s the frequency of this waveform?

But you never stated how many horizontal divisions defined one cycle of your waveform.

If one cycle spans one division, the frequency is 1 / 5μSec = 200KHz
If one cycle spans two divisions, the frequency is 1 / 10μSec = 100KHz
If one cycle spans one half division, the frequency is 1 / 2.5μSec = 400KHz
and If one cycle spans .75 divisions, the frequency is 1 / 3.75μSec = 267KHz

There is no magic that defines the span of a cycle to stay at precisely 1 horizontal division.

and as Sceadwian stated earlier, the vertical deflection has no influence on period or frequency measurements.

 

[Sceadwian]

What’s the frequency of this waveform?

As I think Steaphany was trying to ask, what waveform are you viewing?!

 

[JimB]

There is something about oscilloscopes in the Theory secion of this site.
https://www.electro-tech-online.com/threads/5-zone-alarm-system.44/
Click on the link to see it.

I'm learning about using Oscilloscope, are they as complicated as they seem or I am just green?

Yes they can be complicated, and yes you are probably green!

Anyway if I have Oscilloscope that is set to display 5 volts per division vertically and 5 micro seconds per division horizontally, what is the frequency? I think its 1,000Hz or 100Hz?

I think you forgot to attach the picture.

Also in order to center a waveform on an Oscilloscope which control do you use, its the vertical positioning control right?

There are two shift controls.
Horizontal or X-shift and vertical or Y-shift, the X-shift moves the trace from side to side, and the Y-shift moves the trace up and down.

JimB

 

[pfelectronicstechnician]

Lets see if I can post the picture here. Thanks again.View attachment 62124

 

[pfelectronicstechnician]

It didn't work, what am I doing wrong? I put it on microsoft word?

 

[JimB]

It didn't work, what am I doing wrong? I put it on microsoft word?

Oh yes it did! (For me anyway).

As for your original question, assuming all the controls are in the calibrated position, the voltage is 10v p-p, and the period if the waveform is 10μs.
I will leave it to you to calcualte the frequency from the period.

JimB

 

[atferrari]

Use image files format

Lets see if I can post the picture here. Thanks again.View attachment 62124

You can use this format

 

[pfelectronicstechnician]

That's it atferrari, Thank you. How did you do that, what format did you use? Does it help you guys solve my issue? Thanks again.

 

[atferrari]

Got the image from your .doc and opened it with IrfanView.

Then I saved it as XXX.PNG. That format is much better than jpg to post here .

Hover your cursor on the image icon and the name (including the .png extension) will show up.

Believe it or not I still receive from time to time attachments from big companies where the document is a .doc. PDF is a nice solution and much more elegant.

 

[atferrari]

T = 2 x 5 usec = 10 usec

F = 1 / T = 1 / 10E-6 = 100000 Hz = 100 KHz

 

[pfelectronicstechnician]

atferrari, thank you that is what i came up with also. Thank you very much.

 

[pfelectronicstechnician]

I have another Oscilloscope question.
When the oscilloscope probe is disconnected from the circuit shown in the Figure, the trace becomes flat
and moves up two divisions on the screen. This reaction indicates that?

View attachment 62137

 

[atferrari]

That the point in the circuit has a negative voltage?

To understand that, check what happens when you measure the changing output of a pot.

Stop the .doc thing. Go for .png.

 

[Jugurtha]

Hello,

Here is a great 60 pages document by Tektronix. It is called "XYZs of Oscilloscopes". Althought Tek manufactures scopes, the document is about scopes in general, and is rather detailed.

I also got "Troubleshooting Scopes" (Though I joined their mailing list first, they send brochures for their scopes but send great non vendor-specific manuals often).

https://www.electro-tech-online.com/custompdfs/2012/03/XYZ20of20Oscilloscopes.pdf

Further reading:

https://www.electro-tech-online.com/custompdfs/2012/03/The20Oscilloscope.pdf

https://www.electro-tech-online.com/custompdfs/2012/03/The20Oscilloscope20Part20220.pdf

 

[pfelectronicstechnician]

Thanks guys, I think its "A negative DC component is riding on the waveform"? Thanks again for the help.

 

[WTP Pepper]

It's about knowing your equipment and how to use it. When disconnected it could be picking up mains hum which depending on your trigger levels and timebase settings may appear as a DC offset.
With modern digital scopes you also have to take into account the errors of aliasing, Google it.

 

[pfelectronicstechnician]

The oscillator generates a sine
wave with a small DC component. The waveform produced by the oscillator is shown on the oscilloscope.
The thermistor in the circuit has a positive temperature coefficient. What will happen to the waveform of this
circuit if the temperature rises?
A. The amplitude of the waveform will decrease.
B. The waveform will drift upward on the oscilloscope screen.
C. The waveform will drift downward on the oscilloscope screen.
D. The amplitude of the waveform will increase.

I think its D, correct or not enough info?