Power Supply and Oscilloscope: Definition, Function, and How to Use Them

 Introduction

In the world of electronics and electrical engineering, two crucial measuring instruments and supporting devices are the power supply and the oscilloscope. Both are widely used in laboratory activities, research, product development, and electronic device repair.

The power supply serves as a stable and adjustable source of electrical energy, while the oscilloscope is used to observe the waveforms of electrical signals, both from analog and digital circuits. The two are often used together to analyze and test the performance of electronic systems.

In this material, we will comprehensively discuss the functions, types, operating principles, and how to use the power supply and oscilloscope, complete with application examples and tips for their use in the field.

CHAPTER I: POWER SUPPLY

1.1 Definition of Power Supply

A power supply is an electronic device that provides electrical energy to electronic circuits or equipment. When used, a power supply converts AC (alternating current) from the PLN (State Electricity Company) into DC (direct current) with adjustable voltage and current according to the circuit's needs.

1.2 Functions of a Power Supply

A power supply has several main functions, including:

• Providing stable voltage and current for electronic equipment.
• Protecting circuits from voltage fluctuations, as the output voltage can be controlled.
• Used as a testing tool in laboratory experiments.
• Allowing testing of various electronic devices with different power requirements.

1.3 Types of Power Supplies

Power supplies are divided into several types based on how they work:

1.3.1 Linear Power Supply

A linear power supply works by lowering the AC voltage using a transformer, then converting it to DC through a rectifier (diode), and stabilizing it with a regulator. Its characteristics are:

• Stable output voltage.
• Low efficiency because much energy is lost as heat.
• Large size and weight.

1.3.2 Switching Power Supply (SMPS)

A Switching Mode Power Supply (SMPS) works by chopping up the electric current using a switching regulator. Its characteristics are:

• High efficiency.
• Smaller size and light weight.
• Suitable for portable devices and energy efficient.

1.3.3 Variable Power Supply

This type allows the user to adjust the output voltage. It is typically used in laboratories. There are two types:

• Constant voltage, variable current.
• Constant current, variable voltage.

1.4 Main Components of a Power Supply

• Transformer: Steps down or steps up AC voltage.
• Rectifier Diode: Converts AC current to DC.
• Filter (Capacitor): Smooths the DC signal.
• Voltage Regulator: Stabilizes the output voltage.
• Heatsink: Cools components to prevent overheating.

1.5 How to Use a Power Supply

Basic steps for using a power supply:

Check the type and specifications of the device.

• Ensure the output voltage meets the requirements of the device being tested.

Connect the output cable to the test device.

• Pay attention to the polarity (+) and (-).

Adjust the voltage and current as needed.

• Use the voltage and current control knobs.

Turn on the power supply.

• Observe the voltage and current on the display.

Perform the test.

• Monitor the voltage and current during the test.

Turn off the power supply and unplug it.

1.6 Safety Tips for Using Power Supplies

• Always check the connection polarity.
• Do not set the voltage beyond the rated capacity of the device being tested.
• Avoid touching exposed connections while the device is on.
• Wear insulating gloves if necessary.
• Make sure the power supply vents are not blocked to prevent overheating.

CHAPTER II: OSCILLOSCOPE

2.1 Definition of Oscilloscope

An oscilloscope is an electronic measuring instrument used to display the waveform of an electrical signal. An oscilloscope displays a graph of voltage versus time on a two-dimensional display, where the X-axis represents time and the Y-axis represents voltage.

This tool is essential for analyzing signal characteristics such as frequency, amplitude, and noise, as well as detecting disturbances in a circuit.

2.2 Oscilloscope Functions

Some of the main functions of an oscilloscope are:

• Viewing the waveform of an electrical signal.
• Measuring peak, peak-to-peak, and RMS voltage.
• Measuring the frequency and period of a signal.
• Analyzing digital and analog signals.
• Detecting noise, distortion, and signal interference.

2.3 Types of Oscilloscopes

2.3.1 Analog Oscilloscope

• Uses a cathode ray tube (CRT).
• Signal display is real-time.
• Fast response, suitable for analog signals.
• Less practical and bulky.

2.3.2 Digital Oscilloscope (DSO - Digital Storage Oscilloscope)

• Stores signals in digital form.
• The display is clearer and can be stored or processed.
• It has automation and data storage features.
• Widely used today.

2.3.3 Mixed Signal Oscilloscope (MSO)

• Combines analog and digital signal measurement capabilities.
• Suitable for embedded systems and microcontrollers.

2.4 Main Parts of an Oscilloscope

1. Display: Displays the signal in waveform.
2. Time Base Knob: Sets the horizontal time scale (seconds/div).
3. Volt/Div Knob: Sets the vertical voltage scale.
4. Trigger: Sets the initial time for the signal reading to stabilize.
5. Input Channel (CH1, CH2, etc.): Where the signal probe is connected.
6. Probe: A tool for capturing signals from a circuit.

2.5 How to Use an Oscilloscope

1. Connect the probe to the input channel.

• Use CH1 first.

    2. Connect the probe to the test point on the circuit.

• Check the ground and signal connections.

    3. Adjust the Volt/Div and Time/Div.

• Adjust so the waveform is clear and not too small or too large.

    4. Set the trigger.

• Use AUTO or NORMAL mode.
• Adjust the trigger level so that the waveform is stable on the screen.

    5. Observe and analyze the waveform.

•  Record the amplitude, frequency, and shape of the signal.

    6. Save or document the results (if digital).

2.6 Measurements Using an Oscilloscope

Some important parameters that can be measured:

• Amplitude: The peak voltage of the signal.
• Frequency: The number of waves per second.
• Period (T): The time of one wave cycle.
• Rise time: The time from 10% to 90% of maximum amplitude.
• Duty cycle: The percentage of time the signal is high (in a pulse signal).

2.7 Common Mistakes When Using an Oscilloscope

• Incorrectly selecting the time or voltage scale.
• Incorrectly connecting the probe ground.
• The trigger is not set, causing an unstable signal.
• Using an uncalibrated probe.

CHAPTER III: APPLICATION AND CASE STUDY

3.1 Power Supply Applications

Power supplies are used in:

• Microcontroller testing.
• Powering amplifier circuits.
• LED and DC motor experiments.
• Battery charging (with a current controller).
• Building electronic device prototypes.

3.2 Oscilloscope Applications

Oscilloscopes are used in:

• Analyzing audio signals from amplifiers.
• Testing digital signals from sensors or microcontrollers.
• Observing the response of low-pass or high-pass filters.
• Detecting EMI (electromagnetic interference).
• Measuring the waveform of a function generator.

3.3 Case Study: Oscillator Circuit Testing

Objective:

To observe the output signal of an oscillator circuit using an oscilloscope and supply voltage with a power supply.

Tools and Materials:

• 0–30V variable power supply
• Digital oscilloscope
• NE555-based oscillator circuit
• Oscilloscope probe
• Connection cables

Steps:

• The NE555 circuit is arranged as an astable multivibrator.
• The power supply is set to 9V, and the output is connected to the circuit.
• The oscillator output is measured using an oscilloscope on CH1.
• The volts/div and time/div scales are adjusted.
• The frequency and amplitude of the output signal are observed.

Results:

• A square waveform is visible.
• Frequency 1 kHz, amplitude 5V peak-to-peak.
• The signal is stable thanks to the correct trigger setting.

CHAPTER IV: CLOSING

4.1 Conclusion

Power supplies and oscilloscopes are essential tools in electronics and electrical engineering. Power supplies serve as a stable and regulated energy source, while oscilloscopes allow us to view and analyze electrical signals visually. Understanding these two tools is an essential foundation for students, technicians, and engineers in developing and analyzing electronic systems.

4.2 Recommendations

Users are advised to always read the tool manual before use and to calibrate the tool periodically. A thorough understanding of how these two tools work and how to use them will greatly assist in diagnosing and repairing electronic systems more accurately and efficiently.