Lab: INTRODUCTION TO THE WAVEFORM GENERATOR AND THE OSCILLOSCOPE

Transcription

1 Name EET101/Lab#5; EET121/Lab#5; EGR104/Lab#3 Sec / Night Date Lab Partner(s) Name(s) Lab: INTRODUCTION TO THE WAVEFORM GENERATOR AND THE OSCILLOSCOPE Objectives: Each student will: 1. Know the function of the three basic sections of the oscilloscope. 2. Be able to operate the Keysight 33509B Waveform Generator to set the desired wave shape, frequency, and amplitude. v1 7/17 3. Be able to obtain a meaningful display on the Tek MSO2004B Oscilloscope using the instructions provided. 4. Be able to measure AC Voltage levels manually by counting graticules & multiplying by the vertical volts/div scale. 5. Know the use of Ch 1 or Ch 2 Inputs; AC & DC Coupling. 6. Be able to measure the period and calculate the frequency of a Sine wave signal by counting graticules & multiplying by the horizontal sec/div scale. 7. To measure Voltage, Period, & Frequency using the o scope s Automatic Measure functions. INTRODUCTION: The four most basic types of test equipment that an electronics engineer or technician will use in the lab are the: 1. Volt-Ohm Meter or Digital Multimeter 2. Power Supply 3. Signal Generator or Function Generator 4. Oscilloscope Refer to your ROWAN COLLEGE at BURLINGTON COUNTY, INSTRUCTION GUIDE for using the Keysight Waveform GENERATOR and Tektronix OSCILLOSCOPE. This guide is in the Laboratories Packet, or as a separate packet in the RCBC Electronics Lab, depending on which course you are taking. In the document, follow the instructions on the Waveform Generator and Oscilloscope set-up before performing the measurements in this lab.

2 Page 2 Scope-Gen Lab v1 FA17.docx VOLTAGE VERTICAL MEASUREMENTS NOTE: Set the Generator amplitude to 8 1 khz The control knob on the o scope s front panel marked Scale in the vertical section (large knob above Ch.1 Input connector) adjusts the volts/div value. When it is set to 2 V/div it means that 1 vertical division on the screen = 2V. Peak Voltage (Vo-p, Vpk) Measurements A. To measure the volt (o-p) count the # of div. + fractions of a div. from the 0V point ( ) to the peak of the waveform. 0 V Vo-p Each subdivision is 0.2 of a division. Vo-p = (# of div.) x (# V/div.) Measure the Vo-p of the generator signal Vo-p = ( div) x (2 V/div) = Vo-p B. To measure volt p-p (or pk-pk) adjust the Vertical Position (small knob above Ch.1 Input connector) so the Bottom peak of the waveform sits on the bottom horizontal graticule. Then count the number of divisions + fractions of a div. from the bottom line to the peak of the waveform. Note: Do not count the bottom line. Count how many divisions high the waveform is. Vp-p = (# of div.) x (# of V/div.) Measure the Vp-p of the generator signal. Vp-p = ( div.)*(2 V/div) = Vp-p What is the relationship between Vp-p and Vo-p? 0 V Vp-p

3 Page 3 Scope-Gen Lab v1 FA17.docx C. Change the vertical scale to 5 V/div. If the waveform becomes un-triggered readjust the Trigger Level control until the level is within the Vp-p waveform resulting in a stable display. 1. Move the Waveform back to Center. 2. Measure the Vo-p. Refer to Step A. Vo-p = Vo-p 3. Measure the Vp-p. Refer to Step B. Vp-p = Vp-p 4. How do these measurements compare to those obtained on the previous page? 5. When the Volts/Division is changed, the amplitude of the wave displayed on the o scope changes. Is the actual voltage of the signal changed? Note: For best accuracy display as large a waveform as possible 6. Note the display on the oscilloscope as you vary the generator amplitude. Describe the results observed in your own words. Is the actual signal voltage changed?

4 Page 4 Scope-Gen Lab v1 FA17.docx 7. Set the vertical scale back to 2 V/div., the generator to 8Vp-p, and re-center the waveform. HORIZONTAL MEASUREMENTS The Horizontal scale control knob (sweep rate) in the horizontal section determines the horizontal scale. A setting of 200 µ, (shown on bottom center of display) corresponds to 200 µs/div. This means that each division (1 cm) between two horizontal graticules = 200 µs. Always adjust the Horiz. Scale (sec/div) control to display 1 or 2 sinewaves. A. To measure the period, (T)(in seconds) 1. Adjust the vertical position control so the waveform is centered vertically. T 2. Adjust the horizontal position control in the horizontal??? section to align the 0 crossing of the trace with the left side vertical graticule line. ( T at top of display should be centered horizontally on the screen.) Each subdivision is 20% or 0.2 of a Horizontal division. 3. Period T = (# of horiz div)*(seconds/div) T = ( # of div)*(200 µs/div) = µs = ms 4. f = 1/T Calculate the frequency of the wave in #3 above. (Don t forget to include units in your calculations and show all steps in the space below.)

5 Page 5 Scope-Gen Lab v1 FA17.docx B. Change the Horizontal (sec/div) Scale (sweep rate) to 400 µs/div. 1. Measure the period. T = 2. Calculate the frequency f = of the wave in step B1. 3. Is the frequency different for step B2 vs. step A4? Explain. 4. The Horiz. Scale knob (sweep rate) determines the electrical length, i.e., time duration of the horizontal sweep. When the sweep rate (sec/div.) is changed the number of cycles of waveform displayed on the o scope is changed. Is the actual period or frequency changed? Note: For best Time or Freq. measurement accuracy display between 1 to 2 sinewaves. 5. Observe the display on the oscilloscope as you vary the generator frequency. Describe the results observed in your own words. Is the actual frequency changed?

6 Page 6 Scope-Gen Lab v1 FA17.docx Automatic Measurements 1) Set (and confirm) the Generator output to: 8 1 khz Sine wave Display two complete cycles. (2 V/div.; 200 µs/div.) 2) Re-do the Vo-p, Vp-p, and frequency measurements using the automatic measurement functions. Note: This method is only available on digital oscilloscopes. Refer to the oscilloscope handout included in your lab packet for instructions on setting up and taking automatic measurements (pg. 22). Confirm with o scope s Measure functions: Vo-p = Vpk = High = V Frequency = Hz Vp-p = Amplitude = V ) Change Waveform Generator settings to: 6.4 Vp-p; 7,580 Hz; (Triangle Wave) Confirm with o scope s Measure functions: Vo-p = Vpk = High = V Frequency = Hz Vp-p = Amplitude = V Question: How does the auto measurement technique compare with the manual visual technique in terms of ease of use and accuracy?

7 Page 7 Scope-Gen Lab v1 FA17.docx EET101 - LAB 5; EET121 - Lab 5; EGR104 - Lab 3 Conclusion 20% Should include the following: 1) Summarize some specific types of measurements that can only be made with an oscilloscope. 2) What are some advantages of a digital oscilloscope over an analog one? 3) What measurements can be made with an oscilloscope which are not available with a standard digital multimeter? 4) Add anything else you feel is relevant.