Mini-Lab 1

TITLE: PART I - Instrumentation Review, Digital Multimeters and Power Supplies

OBJECTIVE: • To become familiar with Power Supplies (PS), Digital Multimeters (DMM) and Resistors (R).

Perform resistance, voltage and current measurements. • To become familiar with the lab computer login procedure, course website and equipment

manuals which are available on the website for your use.

ASSIGNMENT In the Log Book, keep a detailed "diary" of the experiment. Report your findings, answering the questions in the handout, and making any additional observations you feel that are relevant.

PROCEDURE a) On the computer, open a web browser and proceed to the course homepage

(http://www.engineering.uiowa.edu/~expeng/). You can access the manuals for the instrumentation on the web site through the “Available Equipment” link. While working on the lab, feel free to use the manuals on the website.

b) You will be provided with a DMM (HP/Agilent U3402A). You will also use either of two HP PS, models 6612C and E3620S. The 6612C PS operation is more complicated than the E3620S, but this difference does not affect this lab.

c) If you have the HP 6612C PS, configure the PS to operate in constant voltage mode with 1 V of output. Press the “Voltage” button, the “Enter Number” button, followed by the “1”, followed by “Enter”, and then turn the power supply output on by pressing the “Output On/Off” button. An example of this type of operation is given on page 42 of the Users’ manual. If you have the HP E3620S, set the dial so the output reads as close to 1 V as possible. Figure below shows the DMM model HP/Agilent U3402A.

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d) Connect the PS you have (either the 6612C or the E3620S) to the DMM, and record PS and DMM output making four reading over the range of the PS. To do this you will have to consult the DMM manual, or use the figure below as a guide. See the Appendix of this handout for additional operating tips.

e) Select a resistor from the component box in the lab. Measure the resistance using both the two and four wire methods and compare the results. See below for help:

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Compare your measured resistance using the DMM with that determined from the color code on the resistor as given below:

Resistor Code

A = 1st digit B = 2nd digit C = Exponent of 10 D = Tolerance It should be read AB x 10c ± D%, and the color code follows the specifications: A, B, and C black = 0, brown = 1, red = 2, orange = 3, yellow = 4, green = 5, blue = 6, violet = 7, gray = 8, white = 9 D gold = 5% and silver = 10%

Did you find the resistor to be within the tolerance indicated by the color band? In other words, determine the % difference of the measured value from the color band value, and is this within ± D%?

f) Set the PS to 2V. Connect the PS, resistor and DMM in series to measure current through R. Record the value of the current flowing through the resistor. Then reconfigure the connection, and reconnect the DMM across the resistor to measure the voltage drop across the resistor. Record all measured values and compare the measurements (V = I R) for the resistor’s voltage and current flow.

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TITLE: PART II - Instrumentation Review: Oscilloscopes and Signal Generators

OBJECTIVE You should become familiar with and operate the Agilent InfiniiVision 2002a Oscilloscope,

which has an integrated 20 MHz function generator to provide stimulus output of sine, square, ramp, pulse, DC and noise waveforms. You will learn how to measure signals using the OS and how to save the data from the oscilloscope to the PC. After this lab, all group members should be capable of producing signals and measuring signals using the oscilloscope, acquiring and storing the signal data on PCs.

PROCEDURE The InfiniiVision 2002a is a 2-channels Oscilloscope similar to the one shown below (which has 4 channels), with nearly identical operational controls and measurement features. You can find the user guide on the course website (http://www.engineering.uiowa.edu/~expeng/Equipment/Agilent-DSO-X-2002A-Manual.pdf). You should feel comfortable in referring the equipment manuals when needed.

Follow the procedure below and record what you do, find and measure in the logbook. Feel free to use functions of the oscilloscope, even if they are not specifically referred to in this write-up. a) Study the cable connections and button positions/functions of the oscilloscope (pages 28 ~ 35

[1]). Record them in your logbook. Feel free to label or number the knobs and buttons to refer to them if you need. Your logbook should be complete enough so that if you need to use this equipment in the future you could do so without consulting the User’s Manual.

b) You will use the built-in waveform generator of the oscilloscope to generate waveforms. Draw the signal cable output location, connections and important buttons in your logbook so you can easily reproduce what you do to generate a signal.

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c) Read the “Waveform Generator” section in the User’s guide [1] (pages 205 ~210) to understand how to generate a waveform. Connect the waveform generator output with the channel 1 input, testing your operational skills using signals (any type, but be consistent) of approximately 1 MHz, 1KHz, and 0.5 Hz. Measure each signal using the OS measurement capabilities (pages 169 ~ 189, Ref. [1]). Record the frequency measured by the OS, and the frequency generated by the waveform generator.

Group members should take turns at the controls of the oscilloscope. If you don't understand the operations ask your teammates for an explanation. As you learn how to use the oscilloscope note the major points of interest and problems you encountered in your Log Book. It is always good to learn from your experiences too if you run into problems, so note them.

Hints: The “entry knob” could be helpful in quickly adjusting the input values; Try the “Auto scale” key to automatically adjust and capture the signal. To measure the 0.5 Hz signal you will probably have to manually adjust the oscilloscope time scale to capture the signal using “Horizontal controls” (pages 43 Ref. [1]) and/or adjust the vertical scale using “Vertical controls” (page 55 Ref. [1]). If the OS measurement function does not work, you will need to manually measure the period of the waveform using the “cursors” (page 159 Ref. [1]) by measuring the time difference of the peak to peak of the waveform, then the frequency in Hz is the inverse of the waveform period.

d) Read “Save/Recall” section of the User’s guide (page 211 Ref [1]), understand how to save the acquired waveform data to a USB storage in specific format (BMP, PNG, CSV, ASCII, etc). Save the acquired signals (1 MHz, 1 KHz, and 0.5 Hz) in CSV format, report your results in plots in your logbook (i.e. no need to include the raw data). Make sure that your plots follow the syllabus requirement, e.g. axes, labels, units, etc.

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Mini-lab 1a Pre-lab Questions

PART I PRE-LAB QUESTION: For the circuit shown below, answer the following questions:

1. If all three resistors are 80 ohms, what is the total resistance of the circuit? 2. If you did not know the value of resistors 1 and 3, and you could freely pick resistor 2,

which of the following options could you use to find the value of resistor 3: a. Measure ONLY voltages across points 1 through 4 (any combinations). b. Measure ONLY currents across points 1, 2, 4, or 5 (any combinations).

3. Describe the procedure you would use to find the value of resistor 3 using your selected option from question 2.

PART II PRE-LAB QUESTIONS:

Read the oscilloscope User’s guide [1] (available on the experimental engineering website) and familiarize yourself with terminology, triggering, acquiring data, scaling and positioning waveforms, measuring waveforms, and setting up the oscilloscope. Answer the following questions. You might also want to read the referenced pages for theoretical background of sampling and aliasing [2] from your text.

• Describe the Auto Scale feature. What does it do? • Note how to save and recall setups, how many setups can be saved, and how to securely erase

the setups? • What is one advantage of each of the three acquire modes (in Acquisition Control): Normal,

Peak Detect, Averaging. How do you change the acquisition mode? • What is actually happening when you change the horizontal position of the waveform? • What is signal aliasing? • How fast must the oscilloscope sample the signal to avoid aliasing? • What is one way to check for aliasing?

5V

Resistor 1

1 2 3

4 5 6

Resistor 2

Resistor 3

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REFERENCES [1] Agilent., TDS Agilent InfiniiVision 2000 X-Series Oscilloscopes User’s Guide. (http://www.engineering.uiowa.edu/~expeng/Equipment/Agilent-DSO-X-2002A-Manual.pdf)

[2] Figliola, R. S. and Beasley, D. E., Theory and Design for Mechanical Measurements, Fifth Ed., Wiley, 2011, pp. 260-269.

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Mini-Lab 1: Appendix

Here are some additional things to know about the HP 34401A DMM.

• Experiment with the “Auto/Hold” button to take average reading.

• Similarly, by taking single readings you can sample you data one reading at a time.

• To change the range follow the instructions below:

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• To set the digits of resolution:

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