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ECE 3300 Lab 2
ECE 1250 Lab 1
Measuring Resistance and Resistive Networks
Overview: This is your first ECE lab! Please install the MyDAQ on your
computer before you come. If you get stuck, bring your MyDAQ to lab with you
anyway. You don’t need to know anything about electrical engineering before
you start, so just come to lab. Bring the equipment below with you. You must
put all results in your lab notebook as described in the separate file about lab
procedures and lab notebooks. Make sure that you have the general section,
procedures, data, and conclusion sections for each subpart within this lab
experiment. In addition, make sure that you include the “Writeup” highlights
throughout this experiment in your lab notebook. To save time, you may print out
parts of the lab handout, such as tables, and put them in your lab notebook as
described in the file about lab procedures and lab notebooks.
Equipment List:
 MyDAQ board, with cables.
 Your laptop (or use the computers in the lab) with Multisim & MyDAQ
software running.
 The following items can be purchased in the ECE Stockroom before (that is
best) or during the lab.
o Breadboard (also called a protoboard) & wire kit
o Resistors (10, 100, 330, 1.0k, 1.5k, 4.7kohm resistors. You will use
these in later labs as well, so keep track of them.)
o Potentiometers (10k and 100 ohm)
o A battery (any battery is fine, such as AAA, AA, C, D, or 9V)
TURN-IN Turn in your completed lab at the end of the lab. Follow your TA's
instructions for turning in the lab. If you are required to scan it and upload it as a
PDF online, there is a scanner in the ECE Stockroom, MEB 2355, or use an app
on your phone (e.g. ‘Genius Scan’ utility for the iphone). If you are required to
turn it in to a homework locker, make sure you put it in the correct lab locker
rather than the homework locker. In either case, make sure your name and the
lab number are clearly legible on your work.
Instructions & Reference Material:
MyDAQ Resource Page (on ECE1250 website)
 Using the myDAQ Digital Ohmmeter DMM(WΩ):
http://decibel.ni.com/content/docs/DOC-12938
 Measuring Current with a Shunt Resistor and DMM
http://www.youtube.com/watch?v=V6Fv79uVrcw
 Using myDAQ Digital Voltmeter DMM(V):
http://decibel.ni.com/content/docs/DOC-12937
Resistor Color Code (See link on ECE1250 resource page. Available online,
textbook, cell phone app, or hardcopy in the stockroom.)
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UNIVERSITY OF UTAH DEPARTMENT OF ELECTRICAL AND COMPUTER ENGINEERING
50 S. Central Campus Dr | Salt Lake City, UT 84112-9206 | Phone: (801) 581-6941 | Fax: (801) 581-5281 | www.ece.utah.edu
ECE 1250 LAB 1
Safety Instructions: There is very little you can do to hurt yourself or your
equipment in this lab. You can touch and handle all of the parts, including the
MyDAQ, its leads, etc. When you connect the MyDAQ for measuring voltage
and resistance, it has a high input impedance, which means it won’t blow the
fuse, as long as you stay within the specs of the device, which this lab does.
Prelab: Watch Lab 1 videos (5 points)
1. Watch the videos posted under lab 1.
WRITEUP: Take notes on the back of this page (or elsewhere) during the videos
so you don’t have to go back and watch them again.
Great ! Your MyDAQ and laptop are working together, so you will be able to build
circuits at home. If you don’t want to have to carry your laptop to lab with you,
you can bring just the MyDAQ, and connect it to the lab computers.
Troubleshooting: When you first use the MyDAQ, the connections for the red
and black leads are a little stiff. Be sure the leads are all the way plugged in to
the MyDAQ. Also see the troubleshooting link on the class MyDAQ page.
If you have problems getting the MyDAQ working with your laptop, we want to
get it working this first week. Bring the MyDAQ and laptop with you, and your TA
can help you get it going. He/she may have you use the lab computers to
complete the lab, and then help you get it going with your computer at the end of
the lab.
WRITEUP: What problems did you encounter, and how did you fix them?
Experiment 1: Measure Resistance (20 points)
1. Use the MyDAQ to measure a resistor, any resistor.
Also measure a short circuit (just touch the black and red leads of the MyDAQ
together), and an open circuit (hold them apart).
WRITEUP: Record the following information in your notebook:
R = ______________ ohms Colors: ____________________
Short =
Open =
2. Learn about the resistor color codes
From the resistor color code, write the colors of 10 ohm, 100 ohm, 330 ohm,
1k ohm, 1.5 kohm, and 4.7 kohm resistors, and determine the % expected
tolerance from the last color band. Find these resistors in your kit and
measure them. Also find the measured % error (which should be less than
the expected tolerance):
(𝑅𝑚 − 𝑅𝑛)
% 𝐸𝑟𝑟𝑜𝑟 =
𝑋 100
𝑅𝑛
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UNIVERSITY OF UTAH DEPARTMENT OF ELECTRICAL AND COMPUTER ENGINEERING
50 S. Central Campus Dr | Salt Lake City, UT 84112-9206 | Phone: (801) 581-6941 | Fax: (801) 581-5281 | www.ece.utah.edu
ECE 1250 LAB 1
where Rm = measured value, and Rn = nominal (or expected) value.
WRITEUP: Make a table similar to the one below or print a copy of this table and
record the following information in your notebook:
Table 1: Resistor color code, expected, and measured values
Color
Band1
Color
Band2
Color
Band3
Color
Band4
Expected
(Nominal)
Value Rn
(ohms)
Expected
%
Tolerance
Measured Measured
Value Rm % Error
(ohms)
(should
be ≤
tolerance)
10
100
330
1k
1.5k
4.7k
3. Measure a potentiometer (pot). A pot has three wires sticking out of it, and a
screw to change its resistance. The center wire is always wire 3, and the other
two can be either 1 or 2 (you decide). Measure Rmax, R13, and R23 for
several different turns of the screw on the pot. Sketch the position of the
screw and report the resistances below. What is the maximum and minimum
possible value of R13 and R23? HINT: It will usually be easier to connect the
pot to the MyDAQ by using alligator clips, rather than trying to hold it by hand.
WRITEUP: Table 2: Potentiometer screw positions and measurement
Sketch Rmax
R13 (ohms)
R23 (ohms)
(ohms)
R13 min =
R23 min =
R13 max =
R23 max =
WRITEUP: Write a conclusion for this section about measuring resistances.
Note any comments, observations, new skills, troubleshooting steps, etc. not
mentioned previously. Also mention any errors and differences in measurements
and account for the differences.
3
UNIVERSITY OF UTAH DEPARTMENT OF ELECTRICAL AND COMPUTER ENGINEERING
50 S. Central Campus Dr | Salt Lake City, UT 84112-9206 | Phone: (801) 581-6941 | Fax: (801) 581-5281 | www.ece.utah.edu
ECE 1250 LAB 1
Experiment 2: Understand and Use the Breadboard (20 points)
1. Breadboard
The breadboard is a convenient way to build and test circuits (breadtype them).
Closely examine your breadboard, compare it to the front and back pictures
below. Identify the pattern where the holes are connected together (shorted
together by the metal on the back side of the breadboard), and where they are
not. Verify your understanding of how the breadboard is connected by sticking
two wires into the board at various locations and measuring the resistance. (You
know what open circuit (not connected) and short circuit (connected) resistances
are based on your measurements in part II.1 of this lab.
WRITEUP: Describe how a breadboard is
used, and what you learned about the
breadboard.
Figure 1 Breadboard front (left) and back (right)
2. Measure resistors in series and parallel
a. Use the 1kohm and 1.5kohm resistors. Connect them in series, using the
breadboard.
WRITEUP: Sketch the breadboard connection and also the circuit
representation. Calculate and measure the series combination resistance and
comment on the difference between the values.
b. Calculate the current and power across each resistor. Make sure it is less
than 0.25W.
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UNIVERSITY OF UTAH DEPARTMENT OF ELECTRICAL AND COMPUTER ENGINEERING
50 S. Central Campus Dr | Salt Lake City, UT 84112-9206 | Phone: (801) 581-6941 | Fax: (801) 581-5281 | www.ece.utah.edu
ECE 1250 LAB 1
WRITEUP: Redraw the circuit now with the 5V supply. Calculate the
expected value for current which uses Ohm’s law which is V=I*R where V is
the 5V supply, R=values of R in series and then solve for I. Measure the
current by measuring the voltage across one resistor and recalculating the
current I using Ohm’s law again. Calculate the power across each resistor by
𝑉2
P=V*I=V*(V/R) = 𝑅 by measuring the voltage V across each resistor. Note
the values and make sure it is less than 0.25W.
c. Connect the 1kohm and 1.5kohm resistors in parallel, using the breadboard.
WRITEUP: Sketch the breadboard connection and also the circuit
representation. Calculate and measure the parallel combination resistance
and comment on the difference between the values.
d. Repeat step (b) for the parallel combination in (c).
WRITEUP: Follow the instructions in part 2(b) but for the parallel resistance
circuit.
e. Now use any combination of your resistors to create the largest possible
resistance.
WRITEUP: Sketch circuit that you create and note the values used for the
resistors. Calculate the expected value, and then measure the value.
f. Now use any combination of your resistors to create the smallest possible
resistance.
WRITEUP: Sketch circuit that you create and note the values used for the
resistors. Calculate the expected value, and then measure the value.
3. Use the breadboard to connect potentiometers in series.
Many electrical devices are controlled by dials, and these dials are often
potentiometers, (see Fig. 2). The variable resistance, controlled by the dial, controls
some other parameter of interest in the circuit. We are going to use two
potentiometers as a set of coarse and fine dials for a variable voltage source. The
variable voltage is adjusted by the resistance, so the variable resistance of the pots
will basically be used to ‘dial in’ a voltage. We will use a 10kohm (10 kΩ) pot as the
coarse adjustment dial, and the 100 ohm pot as a fine adjustment dial. The two
pots will be in series.
WRITEUP: Sketch how you connect your potentiometers (in series) so that you can
have a maximum resistance of approximately 10.1kohms, and a mimimum
resistance of about 0 ohms, depending on how you set the two dials.
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UNIVERSITY OF UTAH DEPARTMENT OF ELECTRICAL AND COMPUTER ENGINEERING
50 S. Central Campus Dr | Salt Lake City, UT 84112-9206 | Phone: (801) 581-6941 | Fax: (801) 581-5281 | www.ece.utah.edu
ECE 1250 LAB 1
100Ω pot
10kΩ pot
3
3
Figure 2. Two pots to be connected in series.
Build this connection of two pots in series on your breadboard, and verify it
(measure the resistances). This means the following connections must be made
using the myDAQ and breadboard:
+5V on myDAQ connects to pin 2 on the first pot
pin 3 of the first pot connects to pin 2 of the second pot
pin 3 of the second pot connects to GND next to the +5V on myDAQ
HINT: Pots come in various shapes and sizes, but they will have three pins, and
the wiper pin is usually between the other two pins. The pot will also have a way
to adjust it: a screw, a slider, a knob, etc.
WRITEUP: Sketch the circuit that you create and measure the values for Rmin
and Rmax obtained by turning the pots all the way one direction or the other.
Rmin =
Rmax =
Conclusion (5 points)
WRITEUP: Write a conclusion that describes what you learned from the
experiments. Discuss any results/data that were collected and anything of note
that wasn’t mentioned as you proceeded through the experiments, (i.e., how
close were the expected results to the calculated values? How close were
measurements obtained by different methods to each other? How accurate were
your results? How do you account for differences and errors? How well did
things work? Did you learn any troubleshooting skills or new skills?) Make sure
to describe your work thoroughly so you can refer back to your notes.
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UNIVERSITY OF UTAH DEPARTMENT OF ELECTRICAL AND COMPUTER ENGINEERING
50 S. Central Campus Dr | Salt Lake City, UT 84112-9206 | Phone: (801) 581-6941 | Fax: (801) 581-5281 | www.ece.utah.edu