User:Nathan Giannini/Notebook/Physics 307L/100830
Oscilloscope Lap Data
SJK 20:53, 28 September 2010 (EDT)
Overall, this is a good primary lab notebook and I think you have the right idea. This particular lab is a little different in that it's mostly exploratory, so it's hard to take notes for reproducibility. The fall time measurements were more quantitative, and you do a good job of describing the method for obtaining the data.
SJK 20:33, 28 September 2010 (EDT)
Great that you record the make and model numbers here.
Setting Up Recieved an oscilloscope, Tektronix TDS 1002 Serial #: UNM JR Lab 004, and wave generator, B+K Precision 4017A Serial #: JR Lab FG 002. Using BNC cables we hooked them together, slots are output on wave generator and CH 1 on oscilloscope, and plugged them in. Richard started up the generator and proceeded with our procedure which is described here
Measuring the sine Wave
1) Counting Grid Lines -- The grids are set in intervals of 1.04V. Increased accuracy can be obtained by turning the Volt/Div knob on the oscilloscope.
2) Using Cursors -- It took Richard and I a few minutes to figure out how to use the cursors, after which we were able to measure the peak to peak voltage difference of our waves.
3) Using Measure -- Measure had a very nice feature to it, in that it gave us the peak to peak voltage instantly. Also we were able to obtain data on our graphs by cycling through different options on the measure menu.
Triggering
Triggering on the Rising Edge -- graph stops when pulse meets a rising voltage Edge Trigger -- generates a pulse when the signal crosses a specified threshold voltage. Video Trigger -- extracts pulses from video formats Delayed Trigger -- waits a specified amount of time after an edge trigger before starting the sweep.
AC Coupling
1) When swapping between AC and DC coupling while using a sine wave, we found that there was a phase shift between them of an amount equal to 680.0 micro seconds. Otherwise, shape and frequency of the wave was unaltered.
2) Measuring the Fall Time
In order to better measure the fall time of our system, we set up a voltage divider as found here. Using this voltage divider, and with a capacitor for Z1, we tried to find the fall time of our system. We ended up asking our class' TA Katie for assistance. She had us re-set up the generator and oscilloscope and then look at a square wave. She then had us bring the frequency down to 10 Hz, where we noticed a exponential curve on our graph, that represented the discharge of the capacitor in our oscilloscope. We then measured the Voltage that the capacitor has before discharge and then when it is at 10% of that voltage. Afterwards, Richard measured the time at both of those points and then put them into the fall time equation: V=V_initial*exp(t/tao) where tao is our fall time. Out Fall Time was 22.66 ms.
3) RC Constant -- Resistance*Capacitance = [math]\displaystyle{ t }[/math] my fall time; which is 22.66 ms.
4) Expected Fall Time Value -- is 10 ms as shown by Gibson in AC Coupling
Experimental Data
Basic Waveform Measurement
Sine Wave at 200 Hz with varying amplitudes
1)
Grid = 4.16 V Cursor Measure = 4.16 V Measure Function = 4.04-4.08 V
2)
Grid = 7.28 V Cursor Measure = 7.28 V Measure Function = 7.28 V
3)
Grid = 2.288 V Cursor Measure = 2.25 V Measure Function = 2.25
4) Large DC Offset Grid at 3 V per square
Grid = 7.2 V Cursor Measure = 7.2 V Measure Function = 7.2 V
AC Coupling
SJK 20:50, 28 September 2010 (EDT)
I am not sure what the 680.0 microseconds relates to, but I'm guessing is a misconception.
AC gives better view of ripples. Also, converting from AC->DC gives a time translation of 680.0 micro seconds.
Fall Time = 22.66 milliseconds
t1 = 0 ms t2 = 21 ms V1 = 4.37 V V2 = 1.73 V
