Physics307L:People/McCoy/Oscilloscope
SJK 02:20, 17 September 2008 (EDT)
This is an excellent summary! Good links to your raw data, and good coherent discussion of everything, along with reporting of "final value". Uncertainty is missing on final value, but you do discuss it, so that's probably just an oversight.
For the oscilloscope laboratory, we were experimenting with the use of oscilloscopes and learning how to use the different features of Digital Storage Oscilloscopes for measuring data, such as amplitude and fall time. The portions of the lab that I completed were the sections on Basic Waveform Measurement, Triggering, and AC Coupling. For a complete description of the procedure used in this lab you can access this link. The section on the Fast Fourier Transform (FFT) was not attempted as I did not have enough time to begin that section during the lab. My notes describing what I did for each portion of the lab along with the results that I had can be accessed by clicking here.
AC Coupling:
The measured Fall Time that I had, as calculated by the measure function in the oscilloscope, was 52.60ms, making the assumed margin of error ±.005ms, due to the presence of 2 significant figures past the decimal point, whereas the margin of error for using the cursors would be ±1ms. To calculate the value I ran a single cycle of a square wave on the oscilloscope, with frequency 79.3mHz and amplitude 45.2V, such that it spiked to the maximum amplitude and then decreased over the period of the wave. I then was able to determine the time constant tau to be equal to .0228s. (Steve Koch:I can get your uncertainty from your above discussion of uncertainty, but you will want to put it on your "final" value too)
What I Learned: Although I have used an oscilloscope before, this was the first time that I ever used a digital oscilloscope, so I learned how to use the measure functions along with some of the other window controls that you don't have on an analog scope. I also learned how to run a single cycle and have the oscilloscope store the image of that cycle, as an analog scope does not permit the storage of an image in its screen.
Exploration outside normal lab procedure: The biggest thing that I examined beyond the defined procedure in the lab was some of the other trigger functions, such as the pulse function and how you can use it to calculate the approximate period in which the input current generates a positive voltage. This also had the feature where it could focus curves such that the period was less than the set pulse value or greater than the value to see the period of the input wave's positive component relative to a fixed pulse time.
Making the Lab Better: The one thing that I would do to make the lab better is to go over the information regarding the time constant on the board in the beginning of the lab so that we would have the rest of the lab to work straight through, rather than doing stuff on the board at different times so that we have to stop and pay attention in the middle of a measurement or statement in our notes. (Steve Koch:Good point, I will probably do that next year.)
