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report_2_ece240l.docxLab Report #2
Introduction
In this experiment we became familiar with the controls and displays of the oscilloscope and function generator. We practiced taking measurements with the oscilloscope and properly stating the known limits or our knowledge. No matter what measurement we are doing, we must state the uncertainty of that measurement. We also designed a simple circuit using a 10kΩ resistor and a 4.7kΩ resistor as shown in figure 2.1 below.
Procedure
Step 1: First, we learned how to use a function generator which produces AC voltage. For this experiment, even though there is a sine wave, square wave, and saw-tooth output option, we used the sine wave option to display on the oscilloscope. We must note when setting up the parameters on the function generator that sometimes it makes assumptions of what we want. In this case, it also assumed that we had an additional resistor attached to our circuit, which altered the peak to peak voltage.
Step 2: After setting the proper parameters on the function generator and hooking it up to the oscilloscope, we adjusted the time and voltage per division on the oscilloscope. The time/division = 50s, and the voltage/division = 1.00V. It is important that we make the graph on the display as large as possible with out the peak and trough of the sine wave being cut off.
We took several measurements and made the corresponding calculations as shown below.
a) Observing the display on the oscilloscope, it showed a sine wave.
b) Using the straight line displayed on the oscilloscope, we measured VL = 0.640 ± 0.032 V, and we measured the frequency to be 1000 ± 20s. Therefore, our fmax = 1020s, fmin = 980s,
VL Upper = 0.671 V and our VL Lower = 0.607 V. From this, we calculated m = 0.320 ± 0.032. Our mupper = 0.366 and mlower = 0.304. Our fdial = 1kHz.
c) We calculated the percent error between the frequency setting of the function generator fmeas and fdial.
% errormax = x100% = 2%
% errormeas = x100% = 0%
% errormin = x100% = -2%
Discussion
When we initially took voltage measurements across our circuit from step 3, we got 2V across each element. This was wrong because the total should have added up to 2V. This gave us the opportunity to troubleshoot the circuit by first testing the connections and then checking our circuit design. We noticed that our ground wire was loose and that our circuit had a break in it, due to not properly utilizing the breadboard. These problems were easily fixed after we had realized what we had done.
Conclusion
Once again, the pre-lab has helped us in identifying which measurements we made were right and wrong. As stated above, we had gotten the wrong voltages across each element, which may have not been seen as incorrect unless we knew the theoretical value. We look forward to not only continuing to explore the many functions of the function generator and digital oscilloscope, but we want to learn about the analog oscilloscope as well. Also, learning more tactics on how to troubleshoot one’s experiment would be very practical.
