User:Alexandra S. Andrego/Notebook/Physics 307L/2009/08/24
|Oscilloscope Lab|| Main project page|
MaterialsSJK 22:39, 14 September 2009 (EDT)
Set UpTo see the Lab guidelines visit the oscilloscope lab wiki page SJK 22:42, 14 September 2009 (EDT)
To begin the experiment the following preliminary steps were taken
Measurments of the Sine Wave
First: Using Grid Lines
The sine wave's amplitude can be measured using the gridlines on the screen of the oscilloscope. Our sine wave is aproximatley two grid lines high which results in about 1 volt.
Second: Using Cursors
By using the cursor function on the oscilloscope we are able to find that the amplitude is more accuratley measured to be 1.04 volts.
Third: Using Measure Functions
By using the measure function on the oscilloscope we are able to find that the amplitude is similarly measured to be 1.04 volts like the cursor function found.
When we take a look at different freqency of the sine waves and the measurment of their amplitudes we were able to see a significant difference in the measurments of the amplitudes. When the Frequency was increased, the amplitude did not increase or decrease in direct corrolation. When we gave the sine wave a large DC Offset we were able to see a very large amplitude for a medium sized frequency.
When we increased our voltage above 12 V the generator was not able to compute the sine wave, and instead gave us a "topped-out" or "flatlined" function.
What is a "Rising Edge"?
A rising edge refers to the positive slope of the signal wave seen on the oscilloscope.
What does the Trigger do to the Signal?SJK 22:41, 14 September 2009 (EDT)
AC coupling removes the DC current where DC coupling takes into account both forms of current but filters out very small frequencies.
Which mode (AC or DC Coupling) is better for viewing a "ripple" on the DC voltage?
The AC Coupling setting makes it easier to view the "ripples" in the DC voltage because the DC Coupling setting shifts the signal to a much higher voltage and hence out of visual range on the Oscilloscope screen. The AC setting allows us to focus the screen more easily to the signal and hence the ripples are more easily seen.
Measure the "Fall Time" for AC Coupling
We measured 50.4ms by using the time function in the cursor menu. We were able to use reference points on our grid by moving our screen area with the position tuning knobs. our 10% value was 2.12V but because of the instruments we were only able to use 2.20V as a reference.
We measured 83.8 ms by using the falltime option in the type category of the Measure function on the oscilloscope. We are not sure as to why this value is much larger than the cursor value gave us.
What RC Constant is Implied?
The RC constant RC<<T Where T is our time constant is implied by our results because the signal resembled spiked changes like described in the circuits web page that we consulted.
Comparison with the Expected Value
The expected value for the fall time of an oscilloscope can be found using the equation -t/[ln(Vf/Vi)]=Tau where Tau is our expected value. So we can plug in values to get our expected outcome.
-52ms/ln(.1)= Tau = 22.58msSJK 22:47, 14 September 2009 (EDT)
If you wish to see my informal summary of this lab follow this link
AcknowledgementsSJK 22:49, 14 September 2009 (EDT)