ECEN 2611
Introduction to Laboratory Equipment
Lab #1
Your Name:
Group Partner(s):
Objectives: The purpose of this experiment is to introduce basic laboratory equipment and to take
some measurements with it. You will use this equipment in this course and in other courses.
Topics: An introduction to voltage, current, and resistance. The operation of Agilent Digital
Multimeter (DMM), Agilent DC Power Supply, Agilent Function Generator, and Heathkit decade
resistance box.
1. Intro to the Laboratory and Safety
The instructor will introduce you to the laboratory and review “Electrical and Electronic Safety
Guidelines” sheet. This should be found on the web site, printed, and after review signed by you.
2. Digital Multimeter
The Agilent 34401A is an example of a DMM which can be used to measure voltage, current, and
resistance. Before explaining how to use the digital multimeter to measure a voltage or current, we
must become familiar with the control buttons used to set the digital multimeter. Looking at the front
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panel of this DMM, we see the following sets of buttons: Measurement Functions (1), Math Operations
(2), Trigger (3), Shift (4), Input Terminals (5), Range (6), and Menu Operations (7).
The function buttons determine the operation of the digital multimeter, such as voltage, current,
resistance, frequency, or continuity measurements. When measuring voltage, the AC V and DC V
buttons select the mode of operation. AC V (or I) gives a measurement of periodic V (or I) values,
whereas a DC measurement gives a value averaged over time. Using the shift button followed by the
AC V or DC V button selects AC I or DC I which measures current. The Ohm, Freq, and Cont buttons
are used to measure the resistance, frequency (or period), and continuity, resp.
In order to get a precise reading you must select an appropriate range for the multimeter. By
using the range/digits buttons the range can be set manually or automatically to change the number of
digits of precision. In the sections below, we will discuss how to measure voltage, current, and
resistance.
a) Voltage Measurements
To measure a DC or an AC voltage, set the range accordingly. Next, connect the black (negative)
probe to ground and touch the red (positive) probe to a point in the circuit where you want to know
the voltage. If you want to measure the voltage difference across a resistor, place the black probe
at one end and the red probe on the other end of the resistor. Remember that voltage measurements are always between two points.
b) Current Measurements
To measure the current in an element or a wire, first select the current mode button and then choose
the appropriate range. Next you must open the circuit in order to connect the digital multimeter in
series with the element. Remember that current measurements give the flow of charge in an
element or wire.
c) Resistance Measurements
To measure the resistance of an element in a circuit, first remove it from the circuit to ensure a
correct (accurate) reading. Next select the appropriate range and mode of operation, and then
connect each end of the element to the digital multimeter.
3. Function Generator
The Agilent 33220A is an example of a
function generator. A function generator is
used to provide voltages that vary with time.
A function generator provides the following
waveforms: sine, square, ramp, pulse, noise,
and other arbitrary waveforms.
These are parameters that can be varied
for each waveform. They include:
a. Amplitude
b. Frequency
c. DC offset
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4. DC Power Supply
When using the Agilent E3631A DC Power Supply start by connecting wire leads to the
appropriate voltage range desired. Once the leads from the power supply are correctly connected to a
proper load, use the output on/off button to enable the output terminals, and then use the adjust knob to
obtain the voltage or current desired.
5. Decade Resistance Box
Our decade resistance boxes provide resistances ranging from 0 to 999,999 ohms. The decade box
has six knobs. Each knob allows you to select its range from 0 to 9, and from knob to knob the values
increase by a factor of ten. Total resistance is the sum of each knob-value times its respective factor.
6. Measurement Exercise
Measuring some body resistances
Begin by using the DMM to measure the resistance between your thumb and index finger on one
hand. You may want your lab partner to hold the probes to your finger and thumb to establish good
contact or press the probes between finger/thumb and bench surface. Repeat this for your other hand.
Describe how you do this, and record and label your readings. (Note that Descriptions are very
important for all your lab reports.)
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Next measure the resistance between your hands by squeezing the probes tightly between your
index finger and thumb of each hand. Compare this value with the resistance between your thumb
and index finger. Use the internet or library to justify your results.
For next lab, type a short paper explaining your results and including all references such as texts,
drawings, etc.
Measuring circuit values
Build the circuit in Figure 1 using decade boxes. Use the DMM to measure the resistances of and
the voltages across resistors R1, R2, R3, R4, R5, and R6. If you need help, please ask your instructor.
Then measure the currents in the resistors R1, R2, R3, R4, R5, and R6. Summarize your results in
the following table and be sure to include units with each value. And describe what you do!
Resistor
Resistor
setting
Measured
value
Voltage Across
Resistor
Current in
Resistor
R1
R2
R3
R4
R5
R6
R3
2k
R1
R4
1k
R5
3k
5k
V1
20Vdc
R2
4k
R6
2.5k
0
Figure 1. Experimental Circuit
Due: End of this lab session.
Format: You should write your reports on the unlined side of engineering paper, and please write
legibly and as neatly as possible. If you wish, reports may be typed and printed, but be sure to include
original data pages. Staple these lab sheets as the cover on the top of your report with the staple put
neatly in the upper left corner.
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