User:Alex G. Benedict/Notebook/Physics 307L: Junior Lab/Oscilloscope Lab

Oscilloscope Lab
This Lab was performed by myself and my partner, Joseph Frye User:Joseph_Frye, on August 23 and 30th.

Set Up
To set up for this lab, we got an oscilloscope and function generator from the equipment closet, and we got BNC cables from the holders on the side of the same closet. We then plugged in the equipment, both of the power cords into the power strip in the table, and one of the BNC cables from the low voltage out on the function generator to the CH 1 in on the Oscilloscope.

Equipment:Tektronix TDS 1002 oscilloscope,BK Precision 4017A 10MHz sweep/function generator

Waveform Measurement
We measured the peak to peak voltage, and the frequency by the three methods suggested in the lab book, we performed three trials for each measurement. The data for the three trials is below.

We discovered during the lab, that the Ranges provided on the back of the oscilloscope 45-440Hz for 100-120V, 45-66Hz for 120-240V, were accurate for the frequencies and voltages it could measure, as it failed for frequencies which were much smaller than 45Hz, and for frequencies much larger than 440Hz, and with a DC offset much larger than 120V it could not measure accurately outside a narrow range of frequencies.

Triggering
We discovered that the Triggering function when set to rising, stops the graph from changing when it encounters a rising voltage, when set to falling, it would move until it encountered a falling voltage, and then stop. The pulse setting was much like the rising and falling triggers,I think it may stabilize the graph based on when it encounters a full period of the wave or something. The video trigger did not seem to settle,and we were not sure what it measured.

AC Coupling
The AC Coupling seems to remove any constant voltage offset. The AC coupling is better for observing changes to the voltage if it is mostly large and changes are small compared with the offset.

When applied to the square wave graph, it produced a curve like a decaying exponential.

When measuring the fall time, it seemed to vary with the frequency of the square wave produced by the function generator. The data from a few trials is below. We wrote the frequency of the measurements next to the trial number. The expected RC constant varies for each measurement, since the expected fall time is from t=0.34/BW where BW is the bandwidth in hertz, which we took to be the frequency of the generated wave.

Data on Sheet 2.

Our observed values were pretty close to the expected value of the RC constants, the mean relative error of the four measurements was about 0.14 for both measurement by cursor and by the measure function.