Lab Project
Oscilloscope DSO-138
Tang Li
301438886
Dec. 12 2024
A report submitted for Centennial College course
ETEC203 Measurement and Instrumentation
Introduction
It is able to display the waveform of the signal and provide time and voltage measurements to help
analyze the characteristics of the signal.
Technical Characteristics
Input Characteristics
Number of Channels: 1
Input Bandwidth: 0 - 200 kHz
Input Impedance: 1 MΩ
Input Range: ±50 V (maximum input voltage)
Input Sensitivity: 10 mV/div to 5 V/div
Coupling Mode: DC/AC/GND switchable
Time Base Range
Horizontal Scale: 10 µs/div to 500 s/div (adjustable in 1-2-5 sequence)
Triggering Characteristics
Modes: Auto, Normal, Single
Trigger Types: Rising Edge, Falling Edge
Size: 2.4 inches
Resolution: 320 × 240 pixels
Digital Storage Properties
Sampling Rate: 1 MSa/s (maximum)
Resolution: 12 bits
Memory Size: 1024 bytes (for waveform storage)
Electrical Characteristics
Power Supply Voltage: 9 V DC (via external adapter)
Current Consumption: Approx. 120 mA
Physical Characteristics
Dimensions: 117 mm × 76 mm × 15 mm (excluding connectors)
Weight: Approx. 80 g (without enclosure)
Operating Temperature: 0 °C to 40 °C
Storage Temperature: -10 °C to 60 °C
User Manual
a1) Controls and connectivity
1.AIN (Input Port): A BNC connector for connecting the input signal to the oscilloscope.
2.Test Signal (TST): Provides a 1 kHz square wave signal for calibration and testing purposes.
3.Coupling Selector (CPL): A switch to select the coupling mode: DC, AC, or GND.
4.Voltage Divider (SEN1): Adjusts the input signal voltage range, toggling between 1 V and 0.1 V.
5.Time Base Selector (SEN2): Selects the time base range with multipliers such as X1, X2, and X5.
6.Ground Pin (DGND): A grounding point for connecting probes or other circuits.
7.LCD Screen: Displays waveforms, trigger information, and measurement results.
8.OK Button: Confirms the selected menu option.
9.Cursor Adjustment (CUR): Adjusts the cursor position for precise measurement of signal parameters.
10.Reset Button: Resets the oscilloscope to its default settings.
11.Select Button (SEL): Toggles through menu options or settings.
12.Up Button (UP): Increases values or navigates up in menus.
13.Down Button (DN): Decreases values or navigates down in menus.
14.Left Button (LEFT): Moves selection left within a menu or setting.
15 Right Button (RIGHT): Moves selection right within a menu or setting.
16.Power Connector (DC 9V): Connects a 9V DC power supply to power the oscilloscope.
17.Voltage Regulator (VR): Stabilizes the input voltage to ensure safe operation.
18.Capacitor (C): Filters and removes high-frequency noise from the power supply.
b) Display
1.Vertical Scale Indicator: Shows the current voltage scale (e.g., "1V") per division on the Y-axis.
2.Coupling Mode Indicator: Displays the coupling mode setting (e.g., "DC" for direct current).
3.Time Base Indicator: Indicates the current time scale (e.g., "1ms") per division on the X-axis.
4.Trigger Mode Indicator: Shows the trigger mode status (e.g., "AUTO").
5.Trigger Level Indicator: Displays the current trigger level setting.
6.Signal Source Indicator: Specifies the signal input source (e.g., "Int" for internal signal).
7.Voltage Measurement Indicator: Shows the instantaneous voltage of the signal (e.g., "0.32V").
8.Waveform Display Area: The primary area where the input signal is visualized with grid lines for
measurement.
9.Trigger Position Indicator: A marker showing the horizontal position where the signal trigger is set.
10.Hold Indicator: Displays whether the waveform capture is currently held (e.g., "HOLD").
11.Waveform Cursor: A vertical line representing the position used for precise measurements.
12.Horizontal Reference Line: A reference level for the zero voltage line in the waveform.
Practical project
The power supply
Buy a 9V power supply line
Oscilloscope usage
Testing is performed on a passive circuit consisting of a 10nF capacitor and a resistor that has the
number of kΩ equal to the last digit of your student ID. If the student # ends in “0’ use 10k.
R C
2+2+2=6k 10 nF
Ω
Test 1
Build a simple RC circuit and connect it to the test signal generated by the oscilloscope, as shown in
the next picture.
Describe the signal, how do you interpret this?
1. Waveform Shape: The waveform consists of horizontal parallel
lines, indicating a periodic signal with relatively low amplitude
variation, suggesting it might be a square wave
2. Voltage Levels: The oscilloscope indicates voltage divisions on
the vertical axis. The amplitude of the waveform seems to stay within
the lower part of the screen, around 0.5V/div.
3. Time Scale: set to 0.2 ms/div
Test 2
Build a simple RC circuit and connect it to the test signal generated by the oscilloscope, as shown in
the next picture (the capacitor is the input now).
Describe the signal, how do you interpret this?
Conclusion
DSO138 oscilloscope is a cost-effective and compact tool ideal for beginners and hobbyists to visualize
and analyze basic electronic signals. Its user-friendly interface, portability, and affordability make it an
excellent choice for educational purposes and low-frequency signal analysis. However, its shortcomings
include limited bandwidth and sample rate, which restrict its ability to capture high-frequency signals
accurately. Additionally, its small display and basic functionality may not be sufficient for more complex
or professional applications. Despite these limitations, it remains a valuable tool for introductory
learning and simple circuit diagnostics.
