Oscilloscope Usage: How to Use an Oscilloscope?
Oscilloscopes are essential tools in electronics.
They help us visualize electrical signals, making it easier to understand what’s happening in a circuit.
Whether you’re a beginner or someone with some experience, this guide will help you learn the basics of using an oscilloscope.
What is an Oscilloscope?
An oscilloscope is a device that displays electrical signals as waveforms on a screen.
These waveforms show how the voltage of a signal changes over time.
By looking at the waveforms, you can understand the behavior of the circuit, find faults, and test components.
Parts of an Oscilloscope
These are the main parts of an oscilloscope.
A. Display Screen
This is where the waveforms appear.
The screen is usually divided into a grid, which helps you measure time and voltage.
An analog oscilloscope shows signals on the screen, which is the visible part of a cathode ray tube, similar to how a tube TV works.
A digital oscilloscope uses an LCD screen, where the data is processed by a computer and displayed.
The screen is divided into small boxes called DIVs.
The time is shown along the X-axis, with each box representing a specific time interval, like 100ms in the example.
This time interval setting is known as the time base.
Changing the time base stretches or compresses the signal’s width.
On the Y-axis, each box represents a certain voltage level, which can be adjusted (like 10mV in the example).
The voltage setting determines how tall the signal appears on the screen.
Adjusting it can make the signal look taller or shorter.
B. Div Control / Time Base
This knob lets you adjust the horizontal scale of the waveform.
It controls how much time is represented by each division (square) on the screen.
With the time base function, you can set the measurement time per division.
For example, if a signal has a frequency of 50Hz, each cycle takes 20 milliseconds.
If you set the time per division to 10 milliseconds, one cycle will appear across two divisions.
The oscilloscope’s bandwidth is important as it shows the maximum frequency it can accurately measure, based on the Shannon theorem.
Modern oscilloscopes can measure time from minutes down to nanoseconds.
Use the trigger Level knob to choose the signal amplitude that starts a measurement.
For instance, if the signal ranges from 0 to 1 Volt, setting the trigger level at 0V will begin the waveform at 0 volts on the left side of the screen.
Setting it to 0.5V will start the waveform at 0.5 volts, shifting the signal in time. The slope switch lets you choose whether the waveform is triggered by an increasing or decreasing slope.
Some devices offer more advanced options, such as single-shot mode, where the signal is displayed only once when the trigger is activated.
In running mode, the signal is displayed every time it crosses the trigger level.
High-quality digital oscilloscopes provide additional trigger options, like triggering on digital pulse sequences.
You can also adjust the X-position to move the signal left or right on the screen.
C. Volts Control
This knob adjusts the vertical scale.
It controls how much voltage is represented by each division.
D. Probes
These are the wires with clips that connect the oscilloscope to the circuit.
Probes pick up the signals you want to measure.
E. Trigger Controls
These controls help stabilize the waveform on the screen.
The trigger makes sure that the waveform doesn’t drift and stays in place.
F. Input Channels
Every oscilloscope has one or more input channel connections, typically found at the bottom of the front panel for stationary models.
This allows you to measure and compare multiple signals at the same time.
BNC connectors are most commonly used, while SMA connectors are preferred for high-frequency oscilloscopes.
Various adapters are available to switch between SMA and BNC connectors.
Modern oscilloscopes include extra pins on the channel connectors, which are used by probes.
These additional pins allow an intelligent probe to communicate its selected attenuation to the oscilloscope.
How to Use an Oscilloscope?
A. Set Up the Oscilloscope
- Turn on the oscilloscope and let it warm up for a few seconds.
- Connect the probe to one of the input channels on the oscilloscope. The other end of the probe should be connected to the part of the circuit you want to measure.
B. Adjust the Settings
- Choose a time scale that lets you see the signal clearly. Start with a broader time scale and adjust it until the waveform looks stable.
- Adjust the vertical scale so that the waveform fills most of the screen without going off the edges. This makes it easier to measure and analyze the signal.
C. Trigger the Signal
- Use the trigger controls to stabilize the waveform.
- Set the trigger level to a voltage value that the signal crosses regularly. This will lock the waveform in place, making it easier to study.
D. Measure the Signal
- The horizontal divisions on the screen represent time. Count the number of divisions that one cycle of the waveform covers, and multiply it by the time/div setting. This gives you the period of the signal. The frequency is the inverse of the period.
- The vertical divisions represent voltage. Measure the height of the waveform and multiply it by the volts/div setting to find the peak voltage of the signal.
Practical Tips
- Always connect the ground clip of the probe to the circuit’s ground. This prevents inaccurate measurements and protects the oscilloscope from damage.
- If you’re unsure, start with the default settings on the oscilloscope. You can adjust them as you learn more about the signal you are measuring.
- Many modern oscilloscopes have math functions that allow you to perform calculations directly on the waveforms, such as finding the mean, maximum, or minimum values.
In Short…
An oscilloscope is a powerful tool for anyone working with electronics.
By understanding the basics of how to use it, you can diagnose issues, test circuits, and gain insights into the behavior of electrical signals.
With practice, using an oscilloscope will become second nature, helping you become more proficient in your work or studies.