User:Manuel Franco Jr./Notebook/Physics Lab 307/2008/09/10

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Oscilloscope Lab

SJK 00:37, 17 September 2008 (EDT)
00:37, 17 September 2008 (EDT)
I like your oscilloscope lab logo!
SJK 00:31, 17 September 2008 (EDT)
00:31, 17 September 2008 (EDT)
I see that you have two pages of raw data notes, this current page and also this other page. I'm going to look at that other page, but only put comments on this page.

Overall, when including the other page, you have very good raw data notes. You took good notes about the things you were doing, and reading them gives me a good idea about what you were doing and thinking. The most important thing missing from your notes is a list of the equipment, including model numbers that you used. What kind of oscilloscope? What brand and model number? What kind of function generator? Do the kinds of cables you were using make a difference? How did you wire things up? A picture, of course, would help a lot as well.

For this lab, I became familiar with a digital oscilloscope. I plugged in the BNC cable from the oscilloscope to the function generator. Then, I created a sine graph on the screen. I then took some measurements:

Measuring Data

SJK 00:33, 17 September 2008 (EDT)
00:33, 17 September 2008 (EDT)
Comments on this section: If this were a "real" lab, in the future, when you're trying to analyze data outside of the classroom, you're going to notice that you're missing some key information: what were your settings on your function generator? How much certainty do you have in your measurements? How do you estimate the uncertainty?

My first sine graph

  • Peak to peak : 1.60 V
  • (max to min): 780mV to -780mV
  • Freq.: 961.5 Hz
  • Period: 1.040 ms

Other Graphs

1.) Increased the volts:

  • Peak to peak : 4 V
  • (Max to Min 'based on cursor'): 2V to -2V
  • Freq.: 1.03 kHz
  • Period: 974 s---? micro

2.) Decreased volts (lowest voltage on the F.G.):

  • Peak to peak : 616 mV
  • (Max to Min 'based on cursor'): 304mV to -304mV
  • Freq.: 975.5  ?Hz micro
  • Period: 1.025 ms

Note: The function generator could be set at any voltage (voltage only determines amplitude). The frequency at which it's set is very essential. If the frequency is too low, you'll get a condensed off scale sine graph. If the frequency is too high, you will just see a line, or half a sine graph. So I adjusted the frequency according, not too high or too low.

Taking Measurements:

1.) Measure Button - Gives data automatically.

2.) The Grid - Using the boxes on the grid, you can determine voltages and times.

3.) Cursor Button - Set cursors, determine measurements.


Triggering enables the user to move along back and forth in the times of the wave.

  • Options on oscilloscope: pulse, video, edge.
    • Edge holds the wave.
    • Pulse holds the wave or moves the wave, based on settings.
    • Video moves the wave based on rise or fall.
  • Rise and Fall
    • Rise oscillates the wave to the right (Increasing).
    • Fall oscillates the wave to the left (Decreasing).

AC Coupling

I applied a large DC voltage of 12V (as instructed),and I decreased the frequency on the function generator substantially down to about 1 X 2.0 Hz. Instead of a round graph, I changed it to square. I adjusted the screen. Then, I measured the fall and rise times by using the measure button, an equation on Wikipedia, and with the cursor button:

I only measured the rise time by the measure button:

  • Rise time: 32.5 micro sec.

The RC constant implies that the time is proportional to the resistance and the capacitance.

The difference in the calculated time verses the cursor is that it's a little lower. The calculated is more accurate than the cursor.

Lab Summary