Download Exp 1-Intro to Basic Laboratory Equipment

Electronic 1(DMT 121)
Laboratory Module
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EXPERIMENT 1
Introduction To Basic Laboratory Equipment
1.
OBJECTIVE:
1.1
1.2
1.3
2.
EQUIPMENT:
2.1
2.2
2.3
3.
To familiarize with the operation of the oscilloscope as a measuring instrument,
and the measurement techniques.
To learn the operation of function generator as a signal source.
To familiarize with the breadboard.
Digital oscilloscope, Bandwidth 40 MHz, Sample Rate 500 MS/s
Function generator
Breadboard
PROCEDURE:
3.1. Familiarization with the oscilloscope
a. Introduction
An oscilloscope (sometimes abbreviated CRO, for cathode-ray oscilloscope, or
commonly just scope or O-scope) is a piece of electronic test equipment that allows
signal voltages to be viewed, usually as a two-dimensional graph of one or more
electrical potential differences (vertical axis) plotted as a function of time or of some other
voltage (horizontal axis).
b. Safety Precautions
You must understand the following safety precautions to prevent to oscilloscope and
probes.
i)
ii)
iii)
Do NOT apply an Excessively High Input Voltage: Each input connector has
rated maximum allowable input voltage. For TDS 1001B, it was rated at 240 V,
60Hz. Use only the power cord.
Check and observe probe rating before using the probes. To avoid electric shock
while using the probe, do not touch metallic portions of the probe head while it is
connected to a voltage source, always keep fingers behind the guard on the
probe body.
Make sure the Ch button (Ch1 MENU or CH2 MENU) is at turn OFF position
before connecting the probe to the scope.
c. Initializing the Oscilloscope
 Basic Operation
After confirming the line voltage, turn off the POWER switch, and connect the power cord
to the line receptacle.
1. Functional Check
Perform this functional check to verify that your oscilloscope is operating correctly.
i)
Power on the oscilloscope.
Push the DEFAULT SETUP button. The default probe option attenuation setting is
10x. The oscilloscope will displays PASSED message at the bottom of the screen.
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ii)
iii)
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On the probe
 Set the switch to 10X on the probe and connect the probe to channel 1 or 2 on
the oscilloscope. To do this, align the slot in the probe connector with the key
on the Ch1 or 2 BNC, push to connect, and twist to the right to lock the probe
in place.
 Connect the probe tip and reference lead to the PROBE COMP terminals.
On the AUTOSET button.
Push the AUTOSET button. Within a few seconds, you should see a square wave
in the display of about 5V peak-to-peak at 1 kHz.
To check individual probe, push the Ch1 MENU button on the front panel twice to
remove channel 1, push the Ch 2 MENU button to display channel 2.
2. Vertical System & Controls
Position and Volts-per-division (volts/div)

The vertical position control allows you to move the waveform up and down on the
display

The volts-per-division (volts/div) setting varies the size of the waveform on the
screen. The volts/div setting is a scale factor. If the volts/div setting is 5 volts, then
each vertical division represents 5 volts and the entire screen of 8 divisions can
display 40 volts from top to bottom.
Input Coupling
Setting determines which part of the signal presented to input is displayed on the
screen.

DC coupling shows all of an input signal

AC coupling blocks the DC component of a signal so that you see the waveform
centered around the zero volts.

Ground coupling disconnect the input signal from the vertical system, which lets
you see where zero volts is located on the screen.
POSITION (Ch1, Ch2). Positions a waveform vertically
CH 1, CH 2 MENU. Displays the Vertical menu selections and toggles the display of the
channel waveform on and off.
VOLTS/DIV (Ch 1, Ch 2). Select vertical scale factors.
MATH MENU. Displays waveform math operations menu and toggles the display of the
math waveform on and off.
3.
Horizontol System and Controls
Position and Second-per-division (sec/div)

The horizontal position control allows you to move the waveform left and right
on the display

The seconds-per-division (sec/div) setting varies the rate at which the waveform is
drawn across the screen (also known as the time base setting or sweep speed).
The sec/div setting is a scale factor. If the setting is 1 ms, then each horizontal
division represents 1 ms and the entire screen of 10 divisions represents 10 ms.
HORIZ MENU. Displays the Horizontol Menu
SET TO ZERO. Sets the horizontal position to zero.
SEC/DIV. Selects the horizontal time/div (scale factor) for the main or the window time
base. When Window Zone is enabled, it changes the width of the window zone by
changing the window time base (Window Zone option is used to define a segment of
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waveform to see in more details (zoom view). The Window time base setting cannot be
set slower than the main base setting.
4.
Trigger System and Controls
An oscilloscope’s trigger function synchronizes the horizontal sweep at the correct point
of the signal, essential for clear signal characterization. Trigger controls allow you to
stabilize repetitive waveforms and capture single-shot waveforms.
The trigger makes repetitive waveforms appear static on the oscilloscope display by
repeatedly drawing the trace at the same part of the waveform. Imagine the jumble on the
screen that would result if each time the trace is drawn across the screen, the drawing
begins at a different part of the waveform.
The trigger circuit acts as a comparator. You select the slope and voltage level on one
input of the comparator. When the trigger signal on the other comparator input matches
your setting, the oscilloscope generates a trigger.
LEVEL. When you use and Edge or Pulse trigger, the LEVEL knob sets the amplitude
level that the signal must cross to acquire a waveform.
TRIG MENU. Displays the Trigger Menu
SET TO 50%. The trigger level is set to the vertical midpoint between the peaks of the
trigger signal.
FORCE TRIG. Completes an acquisition regardless of an adequate trigger signal. This
button has no effect if the acquisition is already stopped.
TRIG MENU. Displays the trigger waveform in place of the channel waveform, while you
hold down the TRIG VIEW button. Use this to see how the trigger settings affect the
trigger signal, such as trigger coupling.
5.
Other Menu and Control Buttons
AUTORANGE. Displays the Autorange Menu, and activates or deactivates the
autoranging function. When autoranging is active, adjacent LED lights.
SAVE/RECALL. Displays the Save/Recall Menu for steps and waveform.
MEASURE. Displays the automated measurements menu.
ACQUIRE. Displays the Acquire Menu.
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REF MENU. Displays the Reference Menu to quickly display and hide reference
waveforms stored in the oscilloscope non-volatile memory.
UTILITY. Displays the Utility Menu.
CURSOR. Displays the Cursor Menu. Cursors remain visible (unless the Type option is
set to Off) after you leave the Cursor Menu but are not adjustable.
HELP. Displays the Help Menu
DEFAULT SETUP. Recalls the factory setup
AUTOSET. Automatically sets the oscilloscope controls to produce a usable display of
the input signals.
SINGLE SEQ. Acquire a single waveform and then stops.
RUN/STOP. Continously acquires waveforms or stops the acquisition.
PRINT. Starts the print operation to PictBridge compatible printer, or performs the
SAVE function to the USB flash drive.
SAVE. An LED indicates when the PRINT button is configured to save data to the USB
flash drive.
3.2. Familiarization with the Function Generator
Function generator is a device that acts like a source of signals. It can generate signals
such as sine, triangle and square waveform, negative and positive pulses and dc levels in
continuous or gated form.
Figure 1.1: Function Generator connected to Oscilloscope
Function Generator Operation:
i)
Connect the function generator with scope according to the above figure.
ii)
Turn on the function generator and allow some time for it to warm up.
iii)
Adjust FREQUENCY ADJUSTMENT to 1.0 and select FREQUENCY RANGE to
1k. (PRESS and TURN clockwise the knob for MAX frequency and invert for MIN
frequency).
iv)
Turn DC OFFSET, SYMMETRY to OFF. (Pull out the knob to select any DC level
of the waveform between ± 10V, turn clockwise to set a positive DC level
waveform.)
v)
Select a sine waveform.
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vi)
Connect Function OUTPUT/50ohm CONNECTOR to the vertical input of the
scope.
vii)
Set the triggering system of the scope to correspond to the vertical input channel,
and adjust the triggering level to freeze the sine wave on the screen. If you do
not see a display, repeat and understand the steps given in section A-4 from
before.
viii)
Now use the function switch to obtain triangle wave and square wave, of the
same frequency.
1.0 Measurement of Periodic Signal:
a. Apart from the observation of waveform of an input signal, one can measure its
amplitude because the Y-axis is calibrated in volts. One can also measure various
time parameter of the signal waveform because the X-axis is calibrated in unit of
time.
b. We first introduce the following parameters
fg =frequency indicated by the notary scale of the generator
fo =frequency obtained by measuring the period T with an oscilloscope.
a) Use the FREQUENCY ADJUSTMENT, FREQUENCY RANGE to sweep through a
broad spectrum of frequency (from very low to very high) of the signal, and observe
the waveforms on the screen
b) Use the Function Generator to select other signals: sine, triangular and square wave
and repeat the previous step.
c) Plot the waveform for each of the sine, triangular and square waveforms, at the
frequency of 4.0 kHz.
d) The frequency of the signal can be obtained by calculating the inverse of the period,
i.e., fo =1 / To . Select the triangle wave and measure the period To corresponding to
the frequency fo = 4kHz respectively. Note also the frequency fg indicated on the
rotary FREQUENCY ADJUSTMENT.
e) The scope can measure the amplitude of any periodic signal waveforms.
i)
Set up a sine wave of your choice at any frequency.
ii)
Adjust the signal amplitude to set the peak-to-peak value is 1V.
iii)
Repeat for a triangular waveform.
iv)
Plot the waves
3.3. Familiarization with the Multimeter
Multimeter is a basic tool in electric and electronic fields. It is a multipurpose device to
measure voltage, current and resistance. Basically there are two types of multimeter
used either in the education or industrial field based on the electronic circuits inside them:
analog and digital meters. The analog meter, broadly known as VOM (volt-ohmmiliammeters) uses a mechanical moving pointer which indicates the measured quantity
on a calibrated scale. It requires the user a little practice to interpret the location of the
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pointer. The digital meter broadly known as DMM (digital multimeter) used number or
numerical display to represent the measured quantity. It has high degree of accuracy and
can eliminate usual reading errors compared to the analog meters. Students should be
adept at using both meters throughout their studies.
Resistance Measurement: For VOM always reset the zero-adjust whenever you change
scales. In addition always choose the range setting that will give the best reading of the
pointer location. As an example, to measure a 500resistance with a range setting of X 1k. Finally do not forget to multiply the reading by the
proper multiplication factor. If you are not sure about the value always starts with the
highest range and going downwards until appropriate scale is chosen. For DMM
-ohms and any with
-ohms and so on. There is no zero-adjust on a DMM meter but make
sure that the resistance reads zero when shunting both leads. Polarity does not concern
in resistance measurement. Either lead of the meter can be placed on either terminal end
of the component, it will be the same.
Voltage Measurement: When measuring voltage levels, make sure the meter is
connected in parallel with the element whose voltage is to be measured. Polarity is
important because the reading will indicate up-scale or positive reading for correct
connection and down-scale or negative reading if reverse connection of the meter test
leads to the resistor’s terminals. Therefore a voltmeter is not only excellent for measuring
voltage but also for polarity determination. Choose the correct function switch for
example DCV to measure dc voltage and turn to the range switch that has slightly bigger
value than the voltage to be measured.
Current Measurement: When measuring current levels, make a series connection
between the meter and the component whose current is to be measured. In other words,
disconnect the particular branch and insert the ammeter. The ammeter also has polarity
marking to indicate the manner they should be hooked-up in the circuit to obtain an upscale or positive measurement. For analog meter pay attention that reversing the polarity
of the meter may cause damage to the pointer. Again always start with higher range
going downwards to avoid damaging the instrument.
The connection of the multimeter to measure different electrical quantities is shown in
both schematic diagram and real wiring illustration in the laboratory in Figure 1.4.
R
Vs
V/
Figure 1.4 (a) Schematic diagram.
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Figure 1.4 (b) Real wiring diagram for illustration.
APPENDIX A: SANWA ANALOG METER
Figure A1: Names of components
a)
i.
Precaution for safety measurement
To ensure that the meter is used safely, follow all safety and operation instructions.
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ii.
Never use meter on the electric circuit that exceed 3kVA.
iii.
Never apply an input signals exceeding the maximum rating input value.
iv.
Pay special attention when measuring the voltage of AC30Vrms or DC60V or more to
avoid injury.
v.
Always keep your fingers behinds the finger guards on the probe when making
measurements.
vi.
Before starting the measurement, make sure that the function or range properly set in
accordance with he measurement.
vii.
Be sure to disconnect the the test pins from the circuit when changing the function or
range.
viii.
For details, please refer instruction manual.
b)
Preparation for Measurement
i.Adjustment of meter zero position
Turn the zero position adjuster so that the pointer may align right to the zero position.
ii.Range selection: Select a range proper for the item to be measured. Set the range
selector knob accordingly.
c) Measuring DC Voltage
i.
ii.
Set the range selector knob to an appropriate DCV range.
Apply the black test pin to the minus potential of measured circuit and the
pin to the plus potential as in Figure A2.
iii.
Read the move of the pointer by V and A scale.
red test
Figure A2
d) Measuring DC Voltage (NULL)
i.
ii.
iii.
Set the range selector knob to an appropriate range.
Turn the adjuster so that the pointer may align exactly to 0 by DCV scale.
Apply the black test pin to the negative potential side of the circuit and the red test
pin to the positive potential side as in Figure A3.
iv.
Read the move of the pointer by DCV scale.
Figure A3
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e)
i.
ii.
iii.
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Measuring AC Voltage.
Turn the range selector knob to an appropriate ACV range.
Apply the test leads to measured circuit as in Figure A4.
Read the move of the pointer by V and A scale. (Use AC 10V scale for 10V range
only)
Note: Since this instrument employs the mean value system for its AC voltage
measurement circuit, AC waveform other than sine wave may cause error.
Figure A4
f) Measuring DC Current
i.
ii.
iii.
Connect the meter in series with the load.
Turn the range selector knob to an appropriate DCA range.
Take out measured circuit and apply the black test pin to the minus potential of
measured circuit and the red test pin to the plus potential as in Figure A5.
iv.
Read the move of the pointer by V and A scale.
Figure A5
g) Measuring Resistance ()
Precaution: Do not measure a resistance in a circuit where a voltage is present.
Turn the range selector knob to an appropriate  range.
Short the red and black test pins and turn the 0  adjuster so that the pointer may
align exactly to 0 . (If the pointer fails to swing up to 0  even when the 0  adjuster is
turned clockwise fully, replace the internal battery with a fresh one.)
iii.
Apply the test pin to measured resistance as in Figure A6.
iv.
Read the move of the pointer by  scale.
v.
Note: The polarity of (+) and (-) turns reverse to that of the test leads when
measurement is done in  range.
i.
ii.
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Figure A6
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