MACASO, JOY M.
BSEE 3
An oscilloscope’s primary function is to provide a graph of a signal’s voltage over time. This is
useful for measuring such things as clock frequencies, duty cycles of pulse-width-modulated signals,
propagation delay, or signal rise and fall times. It can also alert you to the presence of glitches in
your logic or bouncing switches.
This tutorial is meant as a simple, interactive tutorial to get you to the point where you can use the
basic features of an oscilloscope. More details are available in the manual. In particular, you should
look at the “Application Examples” section and the “Front-Panel Menus and Controls” sub-section of
the "Getting Started" section. But if you’re reading this tutorial, that probably means you’d rather
not read the manual, so let’s get started.
Font panel of Oscilloscope
No. Description
DISPLAY
1
2
Screen
Trace
3
Graticule
4
Axis
No.
A
B
C, D
E
Phosphor or an LCD screen, usually about 100 mm corner to corner.
Line drawn by the scope to represent the signal. This line is created by a bright dot moving across
the screen at high speed.
Screen is overlaid with a grid of horizontal (C) and vertical (D) lines, which divides the screen into
squares, called ‘major divisions’, graticule is usually 10 major divisions wide and 8 tall.
The central horizontal and vertical lines are usually thicker than the others and are divided into
‘minor divisions’, usually five per major division.
POWER SUPPLY AND CIRCUIT
5
6
7
8
9
Power ON/OFF
Power lamp
Intensity
Focus
Trace rotation
Scale illum
1
2
3
4
5
6
Press power push button switch to turn the power on and release to turn the power off.
This lamp lights when power is turned ON.
Control the brightness of the display.
Control the sharpness of the display.
Screw driver control to adjust horizontal tilt of the trace.
Used to adjust the scale brightness.
VERTICAL AXIS SECTION
10
11
Input BNC
AC-GND-DC
30, 24
22, 29
12
13
Volts/Div selector
x5 Mag
26, 32
20, 36
14
15
Position
Invert
23, 35
21
Input terminals to CH1/X, CH2/Y inputs.
Selects the coupling method to the vertical amplifier.
AC: Vertical input is connected through a capacitor, only AC component is displayed.
GND: Input of vertical amplifier is grounded.
DC: Input signal including DC component is displayed.
Steps attenuator switch from 5mV/div to 10V/div.
When pressed, the vertical axis gain is magnified 5 times, and the maximum sensitivity becomes
1mV/div.
Used to move CH1 or CH2 trace up or down on the CRT screen.
When Invert switch is pressed, polarity of the signal to CH2 is inverted.
MACASO, JOY M.
BSEE 3
16
17
18
CH1
CH2
Dual
34
28
28, 34
19
ADD
31
Only the signal applied to CH1 is displayed.
Only the signal applied to CH2 is displayed.
When both CH1 and CH2 buttons are pushed in, the signals applied to CH1 and CH2 are displayed
simultaneously in either chopped or alternate display.
Displays the algebraic sum of the CH1 and CH2 inputs. Difference is displayed when the CH2 invert
button is pushed in.
HORIZONTAL AXIS SECTION
20
21
Time/Div Selector
X-Y
15
11
22
Sweep Var
12
23
24
Horizontal Position
x5 Mag
14
9
25
Alt-Mag
8
26
Trace Separation Control
13
Selects sweep speed from 0.1us/Div to 0.2us/Div in 20 calibrated steps.
Displays the CH1 and CH2 input signal as an X, Y graph. The vertical deflection signal is applied to
the CH1 input and the horizontal deflection signal is applied to the CH2 input.
When tuned completely clockwise (cal) the sweep is indicated by the Time/Div switch.
When turned completely counter clockwise the sweep is less than 1/2.5 of the Time/Div setting.
Used to move the trace in horizontal direction.
When pressed, the trace will be magnified by a factor of 5. The sweep time becomes 1/5 of the
value indicated on the Time/Div switch.
Displays both the normal trace whose sweep rate is indicated by the Time/Div switch and the
magnified trace x5 simultaneously.
Used to position Magnified trace 1.5 divisions or more from the normal trace
TRIGGERING
27
Trigger source selector
16
28
29
30
Ext
Trig Level
Slope
19
17
10
31
Trig Mode
18
32
33
34
Cal 0.5V
GND
COMP. TEST
7
27
40
35
Component Test In
42
Selects sweep trigger signal source.
Int: Input signal applied to CH1 or CH2 becomes the trigger signal.
CH2: Input signal applied to CH2 becomes the trigger signal.
Line: Power line frequency becomes the trigger signal source.
Ext: External signal applied to TRIG input becomes the trigger signal.
Input terminal for the external trigger signal.
Sets the amplitude point on the trigger waveform that will start the sweep.
Selects the polarity of the slope the trigger source waveform will start the sweep.
(+) slope is selected when the push button is pushed out.
(-) slope is selected when the push button is pushed in.
Auto: Sweep continuously runs in the auto sweep mode. A trace will be displayed even when the input
waveform is not triggered. A stationary waveform will be displayed when the input waveform is
properly triggered.
Norm: A trace will be displayed only when the input waveform is present and is properly triggered.
There will be no trace displayed if there is no input signal or if the input signal is not synchronized.
Normal sweep is used when the input signal’s frequency is less than 25Hz.
TV-H: Effective when trig mode is set to TV, and is used when the horizontal of the TV signal is
to be synchronized.
TV-V: Effective when trig mode is set to TV, and is used when the vertical of the TV signal is
to be synchronized.
Outputs a 0.5V P-P 1KHz rectangular wave for calibrating probes.
This is the grounding terminal.
Switch to change from oscilloscope to component tester. For component testing, X-Y switch must
be pushed in for X-Y mode and set both AC-GND-DC switches to GND position.
Terminals to connect a component or lead wires to a component under test.
Waveform Measurements in Oscilloscope
You use many terms to describe the types of measurements that you take with your oscilloscope.
This section describes some of the most common measurements and terms.
Frequency and Period
If a signal repeats, it has a frequency. The frequency is measured in Hertz (Hz) and equals the
number of times the signal repeats itself in one second (the cycles per second). A repeating signal
also has a period - this is the amount of time it takes the signal to complete one cycle. Period and
frequency are reciprocals of each other, so that 1/period equals the frequency and 1/frequency
equals the period. So, for example, the sine wave in following figure has a frequency of 3 Hz and a
period of 1/3 second.
MACASO, JOY M.
BSEE 3
OSCILLOSCOPE FREQUENCY AND PERIOD DIAGRAM
Voltage
Voltage is the amount of electric potential (a kind of signal strength) between two points in a
circuit. Usually one of these points is ground (zero volts) but not always - you may want to
measure the voltage from the maximum peak to the minimum peak of a waveform, referred to at
the peak-to-peak voltage. The word amplitude commonly refers to the maximum voltage of a signal
measured from ground or zero volts. The waveform shown in Figure 8 has an amplitude of one volt
and a peak-to-peak voltage of two volts.
Phase
Phase is best explained by looking at a sine wave. Sine waves are based on circular motion and a
circle has 360 degrees. One cycle of a sine wave has 360 degrees, as shown in following figure.
Using degrees, you can refer to the phase angle of a sine wave when you want to describe how
much of the period has elapsed.
OSCILLOSCOPE WAVE DEGREES DIAGRAM
Sine Wave Degrees
Phase shift describes the difference in timing between two otherwise similar signals. In following
figure, the waveform labeled “current” is said to be 905 out of phase with the waveform labeled
“voltage,” since the waves reach similar points in their cycles exactly 1/4 of a cycle apart (360
degrees/4 = 90 degrees). Phase shifts are common in electronics.
MACASO, JOY M.
BSEE 3
OSCILLOSCOPE PHASE SHIFT DIAGRAM
Phase Shift Diagram
VOLTAGE MEASUREMENTS IN OSCILLOSCOPE
Voltage is the amount of electric potential, expressed in volts, between two points in a circuit.
Usually one of these points is ground (zero volts) but not always. Voltages can also be measured
from peak-to-peak - from the maximum point of a signal to its minimum point. You must be careful
to specify which voltage you mean.
OHM'S LAW FORMULAS - FORMULA - FORMULAE
Following figure shows the voltage of one peak - V[p] - and the peak-to-peak voltage - V[p-p]
-, which is usually twice V[p]. Use the RMS (root-mean-square) voltage - V[RMS] - to calculate
the power of an AC signal.
MACASO, JOY M.
BSEE 3
VOLTAGE PEAK AND PEAK-TO-PEAK VOLTAGE DIAGRAM
Voltage Peak and Peak-to-peak Voltage
You take voltage measurements by counting the number of divisions a waveform spans on the
oscilloscope’s vertical scale. Adjusting the signal to cover most of the screen vertically, then taking
the measurement along the center vertical graticule line having the smaller divisions, makes for the
best voltage measurements. The more screen area you use, the more accurately you can read from
the screen.
MEASURE VOLTAGE ON THE CENTER VERTICAL GRATICULE LINE DIAGRAM
Measure Voltage on the Center Vertical Graticule Line
Many oscilloscopes have on-screen cursors that let you take waveform measurements automatically
on-screen, without having to count graticule marks. Basically, cursors are two horizontal lines for
voltage measurements and two vertical lines for time measurements that you can move around the
screen. A readout shows the voltage or time at their positions.
How do you connect an oscilloscope?
Connect the scope probe’s ground clip to the ground plain or connection of the circuit, and the probe
tip to the signal output of the circuit. When these connections are made the oscilloscopes screen will
instantly display a line which is known as the signals waveform. How to Calculate Frequency from
an Oscilloscope To measure frequency of a signal you need to count the number of horizontal
MACASO, JOY M.
BSEE 3
divisions from one of the peaks of the waveform to the next instance of the repeated peak. Then
multiply the number of horizontal divisions by the time per division. This will calculate the signal’s
period. Once you have calculated the perion of the wavefore you can now calculate the signal’s
frequency with the following equation. Frequency = 1/period.
In addition to those fundamental features, many scopes have measurement tools, which help to
quickly quantify frequency, amplitude, and other waveform characteristics. In general a scope can
measure both time-based and voltage-based characteristics: Timing characteristics: Frequency and
period -- Frequency is defined as the number of times per second a waveform repeats. And the
period is the reciprocal of that (number of seconds each repeating waveform takes). The maximum
frequency a scope can measure varies, but it’s often in the 100’s of MHz (1E6 Hz) range. Duty
cycle -- The percentage of a period that a wave is either positive or negative (there are both
positive and negative duty cycles). The duty cycle is a ratio that tells you how long a signal is “on”
versus how long it’s “off” each period. Rise and fall time -- Signals can’t instantaneously go from
0V to 5V, they have to smoothly rise. The duration of a wave going from a low point to a high
point is called the rise time, and fall time measures the opposite. These characteristics are important
when considering how fast a circuit can respond to signals. Voltage characteristics: Amplitude -Amplitude is a measure of the magnitude of a signal. There are a variety of amplitude
measurements including peak-to-peak amplitude, which measures the absolute difference between a
high and low voltage point of a signal. Peak amplitude, on the other hand, only measures how high or
low a signal is past 0V. Maximum and minimum voltages -- The scope can tell you exactly how high
and low the voltage of your signal gets. Mean and average voltages -- Oscilloscopes can calculate
the average or mean of your signal, and it can also tell you the average of your signal’s minimum
and maximum voltage. When to Use an O-Scope The o-scope is useful in a variety of
troubleshooting and research situations, including: Determining the frequency and amplitude of a
signal, which can be critical in debugging a circuit’s input, output, or internal systems. From this, you
can tell if a component in your circuit has malfunctioned. Identifying how much noise is in your
circuit. Identifying the shape of a wave -- sine, square, triangle, sawtooth, complex, etc.
Quantifying phase differences between two different signals.
MACASO, JOY M.
BSEE 3
REFERENCES:
Unknown. (1970, January 01). OSCILLOSCOPE CONTROLS AND OPERATION. Retrieved
October 27, 2020, from https://mohdmuqeem.blogspot.com/2014/09/oscilloscope-controls-andoperation.html?fbclid=IwAR2rnKvMq4tN5o206J6KGL22Fj5fpI8CoOo01EIcVNNeV9iM6FL1B0jKJA
How to Use an Oscilloscope. (n.d.). Retrieved October 27, 2020, from
https://learn.sparkfun.com/tutorials/how-to-use-an-oscilloscope/all?fbclid=IwAR0Q5sFmgcdFBD8xsU9tdnVnj3Ij8KIEmvaqbrfrJwv9JOIHBtJWMR3rrM
Projects, H. (n.d.). About OSCILLOSCOPE Oscilloscope Voltage Measurements. Retrieved October
27, 2020, from
https://www.hobbyprojects.com/oscilloscope_tutorial/voltage_measurements.html?fbclid=IwA
R3AutvLeg-XVeA_XgDKlIXOx1UHvkoB3nZ8NusgmR56lKjUdQCNSk8ykyk