Physics307L:People/Cordova/Matt's Oscilloscope Lab Summary

My lab partner was Sebastian.
The data for this lab can be found here.

Purpose

^{SJK 12:24, 29 September 2010 (EDT)}

12:24, 29 September 2010 (EDT)
This is a good summary and you have a good primary notebook. Note the comment below about uncertainties.

• Learn to read/use an oscilloscope
• Become familiar with proper lab procedure.

Safety

• No outstanding safety concerns.

Equipment

^{SJK 12:21, 29 September 2010 (EDT)}

12:21, 29 September 2010 (EDT)
It's good you have make / model numbers here for equipment. It's also important to record this in your primary lab notebook.

• Tektronix TDS 1002 Two Channel Digital Storage Oscilloscope
• Wavetek Power Supply - Model:181
• BNC Cable

Set Up

• Connect one end of the BNC cable into the Lo Voltage Out on the power supply, and the other into Channel 1 on the oscilloscope.
• We made sure that the power supply was on the lowest voltage setting, and then continued to turn both devices on.

Procedure

• Basic Waveform Measurements
  • After making a connection between the source generator and the oscilloscope, we set the frequency to ~200 Hz.
  • We then set the oscilloscope to the sine wave function.
  • After setting the display to easy to read intervals of 1V per dash and 1ms per grid, the generator was set to ~2V to produce a nice looking function.
• Triggering
  • We fiddled with the trigger menu on the oscilloscope, yielding some insight as to what triggering is.
    • If the trigger cursor is set outside the range of the incoming source, you no longer get a steady image. This leads me to believe that the 'trigger' traces the incoming signal and displays it as a steady image on the screen.
    • If you switch from 'rising/falling' on the trigger menu, the graph is shifted by half a period. This leads me to believe that you can tell the trigger where/when to start tracing the signal.
• AC Coupling
  • When the oscilloscope is set to AC coupling, we have a graph that is symmetrical about V=0. I would assume AC coupling ignores any DC input, since DC current would offset the graph.
  • Following the procedure we were able to measure fall time from the graph which allowed us to calculate [math]\displaystyle{ \tau }[/math].
    • [math]\displaystyle{ \tau=T_{falltime}ln(10) }[/math]
    • [math]\displaystyle{ \tau=63.31*ln10=29.66 }[/math]

^{SJK 12:23, 29 September 2010 (EDT)}

12:23, 29 September 2010 (EDT)
For future labs it will be critical to discuss uncertainty on your measurements and we'll be learning about that in lecture. You'll also compare to accepted values and discuss discrepancies, systematic error, etc. That was tough to do in this lab but will be important for your subsequent summaries.