User:Emran M. Qassem/Notebook/Physics 307L/2010/08/30

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Oscilloscope Lab

SJK 15:13, 24 September 2010 (EDT)
15:13, 24 September 2010 (EDT)
The pictures of setup are great. Important, though, to record the make and model numbers of the equipment here in your primary notebook.
  • We got the equipment, which included a signal generator and a Oscilloscope. We got a BNC to BNC cable and connected output from the function generator to channel 1 on the oscilloscope. We plugged everything in, turned it on, and started playing.
  • AC and DC coupling is how the Oscilloscope interprets the signal the function generator is producing. It can interpret as AC or DC which means Alternating Current or Direct Current. If it is reading as AC, then it will only look at the AC part of the signal about the horizontal axis. If it is reading as DC, then it will look at both the AC part and the DC offset to the wave, to move it up or down based on what the signal has for DC. We also noticed that the square wave looks more square with DC coupling.


Basic Measurements

  • Measuring using Voltage divisions and time divisions, we obtained the following:
    • 6 blocks at 1 volt each block, approx 6 volts.
    • 2 blocks from peak to peak, at 2.5 ms, approx 6ms, freq = 1/s = 1/(.005 s) = 200 Hz
Cursor Horizontal
  • Using the cursor, we turned the two position nobs to set the top horizontal bar and the bottom horizontal bar to get 6.12 Volts
Cursor Vertical
  • Using the cursor again, but with vertical bars, we turned the two position nobs to set the left and right vertical bars, giving us 200 Hz, and 5.000 ms.
Measure Button
  • To measure, we pressed the "Measure" button on the oscilloscope.
    • Peak to peak voltage - 6.20 V
    • Frequency - 200.8 Hz
  • Using a large amplitude, we found the following:
    • with Measure, 22.4 V
    • with Cursor, 22.2 V
  • Using a very small amplitude, we found the following:
    • with Measure 2.08 V
    • with Cursor 2.10 V
  • Using low amplitude, and large DC offset we found the following:
    • It is very hard to get the trigger to catch
    • Measure tool gives back 2.20 V for peak to peak
    • Frequency seems to be jumping around between 130 and 300 when it should have been 200.
    • Cursor tool gives an amplitude of 2.00 V peak to peak.
    • Perhaps a large DC offset with a low amplitude would be hard to read.


  • Trigger rising slope means that when the wave rises in a positive slope and crosses 0, the wave will be timed so that it shows up as an image instead of moving all over the place. Falling is the opposite, in that it catches the negative slope crossing the 0 at the trigger line and sets the wave to an image.
  • Trigger with pulse and not equal setting makes the image still. Pulse checks the width of a hump or spike, at the level the trigger is set at, and hold still if it matches the criteria specified, such as equal, greater than, less than,or not equal.

AC Coupling

Square Wave Fall Time
  • AC Ripple on the DC signal is off of the RC circuit.
  • Fall Time is measurable at low frequency. We measured with cursor at 10 Hz and 7 V and found that the the fall time was 45.20 ms. With measure, we got 39.99 ms.
    • This is has a tao of fall time / 2.197 which is the RC constant.