EECS 318
Electronics Lab
Laboratory #2
Electronic Test Equipment
Objectives:
The purpose of this laboratory is to acquaint you with the electronic sources and
measuring equipment you will be using throughout this course. During this lab, you will
be asked to use these instruments to perform a variety of simple measurements of
voltage and resistance.
Equipment:
1 - Analog Probe Kit (YOU need to check out)
1 - DC Power Supply (Agilent E 3630A)
1 - Digital Multimeter (FLUKE 8050A)
1 - Function Generator (Hewlett Packard 33120A)
1 - Oscilloscope (Agilent)
Components:
1 - 100Ω Resistor
1 - 1kΩ Resistor
1 - 10kΩ Resistor
1 - 100kΩ Resistor
1 - 5 kΩ Potentiometer
1 - Photodiode
Procedure:
1. A digital multimeter (shown below) measures electrical voltage (AC and
DC), current (AC and DC), or resistance.
Digital Multimeter (FLUKE 8050A)
Measure the voltage of a battery and note down the reading. Reverse the leads
and observe what the meter does.
Q1: What is the reading on the multimeter for the battery? What happens when
the leads are reversed?
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2. A DC power supply (shown below) supplies electrical DC power. Notice that
this supply can generate three different voltages simultaneously in ranges: 0 to
+6 V, 0 to +20 V, and –20 V to 0. Each of these voltages is generated from the
respective positive terminal (note the labels) and the common (black) terminal.
Note that the common terminal is the same for all three voltages.
DC Power Supply (Agilent E 3630A)
Set the multimeter to the 2-VDC range. Using jumper cables, connect the
positive (red) and negative (black) terminals of the multimeter to the 0-6 V
output terminal (red) and the com (black) terminal of the power supply,
respectively. Select the +6 V meter setting on the power supply, and turn the +6
Voltage adjust knob to its fully counter-clockwise setting. Slowly increase the
voltage control of the power supply from 0 to 6 V in 1 V increments. Compare
the readings on the power supply meter with the multimeter.
Q2: What happens to the multimeter display when the voltage exceeds 2V?
How can this be avoided?
It is a good practice when measuring a completely unknown voltage to start out
on the highest range and move downward until the desired resolution is
obtained. Try this with the voltage control turned up a little higher.
3. Using the multimeter, measure the resistance of each of the 4 fixed, twoterminal resistors (100Ω, 1kΩ, 10kΩ, 100kΩ) and record the measured
resistance values along with the color code for each.
Q3: Record the readings in the table below? Are all of the resistors
within the tolerance indicated by the color code?
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Indicated values
Measured values
Color Code
Within tolerance (Y/N)
100Ω
1kΩ
10kΩ
100kΩ
4. Using the multimeter, measure the resistance between the two outer pins of
the variable resistor using mini grips provided in the kit (5kΩ potentiometer).
Q4: Does this resistance change appreciably (i.e. more than 1 kΩ when the
“slider” is rotated?
5. Using the multimeter, measure the resistance between the inner pin and both
of the outer pins of the potentiometer (inner and 1st outer pin followed by inner
and 2nd outer pin) for few different settings of the “slider”.
Q5: Does this resistance change when the plastic “slider” is rotated? For
each slider setting, do the two resistances always add to the same value
of 5 kΩ? Why?
6. With the multimeter set to DC volts, measure the voltage across the pins of
the photodiode (the two-pin device with the circular, plastic window).
Q6: Does this voltage change when you shield the window with your
hand?
Q7: What does this device seem to do? What could it be used for?
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7. A function generator (shown below) produces a variety of voltage wave shapes
(including the square wave and the sine wave) of various amplitudes and
frequencies. It is often used as an AC voltage source in electronic
measurements.
Function Generator (Hewlett Packard 33120A)
Note that the frequency and amplitude values can be set using the controls
shown below:
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8. An oscilloscope or “scope" (shown below) is the basic instrument for dynamic
measurements. The utility of this instrument lies in its tremendous flexibility. It can
be used to observe voltage signals ranging in amplitude from a fraction of a
millivolt to hundreds of volts at speeds from nanoseconds to as much as minutes.
An oscilloscope can be used for many different purposes. This experiment will not
cover the full functionality of the oscilloscope. Additional techniques will be taught
in future experiments.
Oscilloscope
Note: the probe ratio for a BNC to BNC cable is 1:1. Make sure you set it up
before doing any measurements. To do that, go to the menu button marked 1
(CH-1), select Probe; change the probe ratio to 1:1 using the push-to-select
button.
9. In general, the oscilloscope has three major sections, which control the operation
of the instrument. They are the “VERTICAL" control section, the
“HORIZONTAL" control section, and the “TRIGGER" control section. There
are many other minor knobs controlling various functions.
The first section is the “VERTICAL" section, into which the outside signals
are fed. The input signal controls the vertical position of the oscilloscope trace.
Your scope has two channels (CH-1 & CH-2) to receive outside signals. Press
1 to activate display of the channel one input. Set the “coupling” mode to DC
by changing the setting located at bottom left of screen. (This setting means
that the vertical deflection will be determined by the total “AC + DC” input
voltage.)
The second section is the “HORIZONTAL" control section. This section
controls the rate at which the oscilloscope trace is scanned horizontally to
“stretch” out the vertical deflection and make the trace look like a
waveform.
The third section is the “TRIGGER" control section. Press Trigger and then
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Press Edge, then select Type=Edge, Source=1, Slope=rising, Coupling=AC.
(This setting means that the trigger circuit will ignore any dc component of
the input signal)
10. Turn the function generator on and set it to generate a 1 KHz sine wave with a
peak-to-peak voltage of 2.0 V and a DC offset of 0. Using a BNC-to-BNC
cable, connect the output from the function generator to the CH-1 input of the
oscilloscope. Press the “default setup” button on the oscilloscope. The default
setup button is an important feature of the oscilloscope and is used to reset all
settings to their default values. The default setup button can be used anytime
when you make wrong adjustments. Change the horizontal and vertical setting
to arrive at a reasonable sine wave display on the oscilloscope. There will be a
display on the scope screen informing you about the settings and can be found
on the upper section of the display.
Q8: What are the horizontal and vertical settings that the default setup has
chosen for this waveform?
11. The oscilloscope has a cursor feature that enables you to measure the amplitude
and period (the time for one cycle of the wave) of the signal displayed on the
screen. Use the CURSOR function to set cursors for the time durations and
amplitude swings. To measure the peak to peak (p − p) amplitude of the signal,
press CURSOR menu then select mode=manual, Source=1, Cursors=Y1. Next,
choose Y1, and rotate the entry knob so that the horizontal cursor “rides” on the
top peak of the waveform. Next, choose Y2, and rotate the cursors knob so that
the new horizontal cursor “rides” on the bottom peak. The p − p voltage
difference between the two cursors (in this case, the p − p voltage) will appear
on the screen.
Q9: How does the measured signal amplitude on the oscilloscope shown as
∆Y on the screen compare with the value shown on the function
generator? Also note down the reading observed.
12. Press 1: select Probe; change Probe Ratio from 1:1 to 10:1.
Q10: How does the measured signal amplitude on the oscilloscope compare
with the value shown on the function generator?
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13. Next set the mode to “Normal” by pressing the Mode/Coupling button found
next to the Cursors button and then selecting the “Normal” mode found on the
left bottom of the oscilloscope display. To measure the time (e.g., the period of
the sine wave), press Source=1 and get into the cursor menu by pressing the
CURSOR button. Next, choose X1, and rotate the cursor knob so that the
vertical cursor intersects one of the zero-crossings of the waveform. Next,
choose X2, and rotate the entry knob so that the new vertical cursor intersects a
zero crossing one period after the first cursor. The Dt time difference between
the cursors and the corresponding frequency f =1/ Dt will appear on the
screen.
Q11: How does this compare with the frequency indicated on the function
generator dial? Also note down the reading observed.
14. Now, go back to the “Trigger" section. Set the SLOPE control to the
“Falling” setting and observe how the trace changes.
Q12: What happens after the setting is changed to “Falling”?
Reset Probe Ratio to 1:1. Set “coupling” mode to “DC” to include DC
components measurement from the signal. Press the “offset” button on the signal
generator and set the display value to +1.0. This adds a +1.0 DC component to
the sinusoidal output.
Q13: How does the displayed waveform change?
15. Press the 1 button, set the “coupling” to “AC”. This sets the oscilloscope
vertical section to ignore the dc component of the input signal.
Q14: How does the displayed waveform change as the vertical coupling mode
is changed from “DC” to “AC”? What advantage could you envision
to using the “AC” coupling mode when displaying signals?
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