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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.
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 or during
the lab.
o 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)
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.)
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.
I.
Prelab: Install the MyDAQ on your computer
(20 points)
1. Put your name and contact information on your MyDAQ, cables,
protoboard, calculator, textbook, etc. Everyone’s looks the same, and it
would be bad to lose!
2. Install the NI MyDAQ Software
a. If you have a DVD & DVD reader: Follow the Getting Started with
NI MyDAQ instructions that came with your MyDAQ.
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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 3300 LAB 2
b. IF you do not have a DVD reader instructions are posted on the class
website for how to download Multisim and MyDAQ software.
c. IF you have a Mac instructions are posted on the class website for
how to download Multisim and MyDAQ software.
3. Measure the voltage of a battery: Follow the instructions for the ‘First
Measurement with NI myDAQ’, and measure a battery (A,AA,AAA,D,C cells
are all OK). If you do not have a battery, you can buy one at the ECE
stockroom in MEB 2355. For more detail on how to measure voltage with
the MyDAQ see http://www.ni.com/example/31436/en/
4. Watch the videos posted under lab 1.
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?
2
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 3300 LAB 2
II. Measure Resistance
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).
R = ______________ ohms
Short =
Open =
2. Learn about the resistor color codes
From the resistor color code, write the colors of the resistors below, 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
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.
Sketch Rmax
(ohms)
R13 min =
R23 min =
R13 (ohms)
R23 (ohms)
R13 max =
R23 max =
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 3300 LAB 2
III. Understand the Protoboard
1.
The protoboard is a convenient way to build and test circuits (prototype
them). Closely examine your protoboard, 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 protoboard), and where
they are not. Verify your understanding of how the protoboard 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.
Figure 1. Protoboard front (top) and back (bottom)
2. Measure resistors in series and parallel
a. Use the 1k and 1.5k resistors. Connect them in series, using the
protoboard. Sketch the protoboard connection and also the circuit
representation. Calculate and measure the series combination and
compare them.
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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 3300 LAB 2
b. Connect them in parallel, using the protoboard. Sketch the protoboard
connection (above) and also the circuit representation. Calculate and
measure the parallel combination and compare them.
c. Your resistors are typically ¼ Watt resistors. For the series circuit in (a)
with a 5V voltage supply, 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 3300 LAB 2
d. Repeat for the parallel combination in (b).
e. Now use any combination of your resistors to create the largest possible
resistance. Sketch it. Calculate it, and compare it to your measurements.
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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 3300 LAB 2
f. Now use any combination of your resistors to create the smallest possible
resistance. Sketch it. Calculate it, and compare it to your measurements.
3. Use the protoboard to connect potentiometers in series.
Many electrical devices are controlled by dials, and these dials are often
potentiometers. 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
in a later part of this lab. 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 1kohm pot as the coarse adjustment dial, and the 100
ohm pot as a fine adjustment dial. The two pots will be in series. Sketch
(below) how you could 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.
10kΩ pot
100Ω pot
3
3
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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 3300 LAB 2
Now build this connection of two pots in series on your protoboard, and verify it
(measure the resistances). HINT: This should look similar to the two pots in
series shown in Figures B.2 and B.3 of your lab manual. It may be slightly
different, because you may not have exactly the same kind of pots shown in the
manual.
Rmin =
Rmax =
8
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