Oscilloscopes are considered one of the top tools for any tester or electronics engineer. An oscilloscope is electric test equipment that will allow you to see waveforms and check whether there is any problem in an electronic circuit. But how to use an oscilloscope?
Since they offer a wide range of benefits, oscilloscopes have become important pieces of test equipment for area testing electronic hardware or electronics laboratory; whether within the repair, service, electronic manufacturing, general electronics circuit design, or anywhere that waveforms and electronic circuits on them that needs to be investigated.
This piece of equipment allows you to measure electronic signals and can be found in a lot of scientific laboratories. The device has been used to observe and study varying-signal voltages on a 2-D (two-dimensional) grid that represents time.
When you connect the oscilloscope to a power source, the device will show the corresponding real-time waveform instantly. While oscilloscopes are mostly used in the fields of engineering and science, they often have been used in other fields like medicine and telecommunication as well.
How to use an oscilloscope?
Whatever type of oscilloscope you use (analog or digital), there are some basic controls that remain the same. Some of these controls include:
- You will see at least one input where the coaxial cable, or the oscilloscope probe, can be attached. However, you have to ensure that you have one of these cables.
- There will be a screen with a grid overlay, which is quite useful when you want to make the measurements using the scope.
- Volts/Div control will allow you to change the number of volts is being represented by each grid overlay’s vertical increment on the screen. In short, you will be able to zoom in and out along the y-axis.
- Time/Div is the control that will allow you to change how much time is represented by each increment on the horizontal axis of the grid overlay on the LCD. This means that you will be able to zoom in and out along the x-axis.
- Vertical position/Offsets will help you move up and down the y-axis.
- The horizontal position/Offset will help you move from left to right.
- A trigger level is a tool that will help in the stabilization of the waveform on the screen.
Setting up the device
When you turn on your oscilloscope and see a flat line, it means that nothing is connected to the oscilloscope; this is identified when the input’s voltage value does not change over time. If you see a line that is not flat, you can try to disconnect the probe. If you see a blank screen, you can try out any of the following:
If your oscilloscope has a dual-channel scope, it means that it has two inputs. You first need to press on ‘Channel 1’, which will change the color of the screen to yellow; pressing the same button again will cause the screen to go blank again.
If you press on ‘Channel 2’, the color of the screen will turn blue; alternatively, it is also possible that your oscilloscope may only have a single input or more than two. Analog scopes will not denote separate channels in different colors; it will only be shown in green.
If you get zoomed in on the blank spaces, you can try rotating counter-clockwise the Volts/Div knob to zoom out. Additionally, you can also try to turn the vertical position control until the line in the center of your screen is flat.
1.Connecting to the oscillating signal
To get to this step, you will have to have a steady signal with a constant frequency. You can even use a waveform generator (if you have one) and set it on a pulse of 2.5V amplitude at 500Hz. In case you do not have a waveform generator, you can use the following alternative:
Arduino: If you are equipped with an Arduino, you can simply load the code below it. Once done, the device will start generating a square wave between 0 and 5V at 500Hz.
2.Setting the trigger
After you connect the signal, you will see a flat line turning into some kind of waveform. Next, you need to adjust and turn the Time/Div so that you can see the separation between each oscillation. Next, you need to change the vertical position and Volts/Div so that you can see the oscillations within the screen. If not, you can rotate the trigger level dial and wait for it to happen.
Alternatively, if your oscilloscope has more than a single channel, you can set the trigger to match the requirement of any channel.
When you turn the trigger level dial, you should notice that the trigger level indicator will start moving upwards and downwards. When this indicator exceeds a certain height of the waveform, the signal will start to become unstable.
This trigger level is basically a voltage level that your oscilloscope will compare the incoming signals with. Since triggering is a bit complex, most people tend to make use of external sources of the trigger to specify special trigger modes.
How does an oscilloscope work?
A traditional oscilloscope works in the same function as a cathode-ray tube television. In fact, these devices are also known as cathode-ray oscilloscopes.
When it comes to a television, the electron beams are scanned repeatedly across the screen, which is sprayed with special chemicals known as phosphors. This means that each time the beam hits the screen, it will light up the phosphors. This takes place a thousand times within a second, which is why you will see a moving picture, instead of a still one.
In an oscilloscope device, the electron beams will work in the exact same way; however, the device will draw a graph instead of building a picture. On the screen, you will see a line is being drawn on the screen; in reality, you are actually looking at a wobbling electron beam that is bumping up and down.
You need to remember that the electrical signals are fed into the X- and Y-axes to provide you with the appropriate values on your screen.
- Waveform baseline icon. Shows the zero volt level of the waveform.
- Channel indicator.
- Channel scale factor.
- Time per division.
- Trigger slope.
- Date and time.
- Trigger level icon.
- Visual representation of waveform.
So, the next question here is how does the oscilloscope draw the trace? You need to imagine that you are an oscilloscope and holding a pencil at point zero on a graph paper. Now, think that your hands are tied to two electric motors – one hand on the X-axis and the other on the Y-axis. These motors are then connected to electronic circuitry that will sample different kinds of samples.
For instance, you can imagine that the X-circuit is connected to an electric quartz clock. When the clock ticks, it will forward a signal to the X-motor so that your right hand will move slightly. After a few seconds, your right hand will move along the horizontal line.
Now, let us consider that you connect the Y-circuit to a heartbeat-detection instrument. If you connect the X- and Y-circuits at the same time, your hand will start moving across the page; however, it will jump up vertically for every heartbeat. This will give you a classic heartbeat trace that you see in the hospitals.
Now, you need to replace the graph paper and a pencil with a screen and an electron beam. Now, you will understand exactly how a typical oscilloscope draws the trace. Each time a signal goes through the Y-circuit, the electron beam will jump. During this time, the trace will keep moving from left to right on the X-axis (horizontal line).
How to read oscilloscope?
The signals in an oscilloscope are sampled as they change over time and then plotted on a display. The signal’s amplitude is plotted on the Y-axis (vertical) and the time on the X-axis (horizontal). In the case of modern electric oscilloscopes, the changes in the signal can occur within any time-space, ranging from a billionth of a second or as long as a few hours.
If you want to understand how to analyze waveform traces, you need to take a closer look at the four distinct characteristics of a waveform:
- Amplitude (the vertical axis)
- Time (the horizontal axis)
- Shape and distortion of the waveform
- Disturbances in the waveform, especially from outside
There are some common types of waveforms like:
Commonly, repetitive waveforms need to be symmetrical. If you print, cut, and paste the traces one upon another, both sides need to be identical. The difference between the two waveforms could indicate a potential problem.
Rise and fall
This pattern is very common in pulses and square waves. This type of waveform can affect the effectiveness of the digital circuit’s timing. If you want to see an edge with a greater resolution, you may have to decrease the time per division.
You need to ensure that the level is within the limits of the circuit’s operating specifications. You also need to check for consistency from a one-time point to another. You will have to keep a close look at this waveform for some time to check on any changes in the amplitude.
This type of waveform will determine the location of the ground reference marker. You can evaluate any DC offset and check whether it fluctuates or remains stable.
Period time changes/wave shape
Circuits, like oscillators, will produce waveforms within constant repeating periods. If you want to spot any consistencies, you will have to check each time period using cursers.
Random noise/Glitches or transients
When you derive waveforms like switches and transistors from active devices, anomalies, it can result in various phenomena like bad contacts, propagation delays, and timing errors.
How to use an oscilloscope to measure voltage?
It is very easy to measure the voltage with the help of an oscilloscope. All you need to do is follow the steps mentioned below:
- First, you need to switch on the oscilloscope and tap on the ‘Default Setup’ button. Then, you need to plug in the probe to Channel 1; however, you do not have to worry so much about the probe. Additionally, it would be helpful to have a clip that will help you prevent you from holding the wire.
- You will have to find a reliable grounding point and then connect the ground clip to it. After this, you need to connect the tip of the probe to the signal that you want to measure.
- Once you have completed the steps mentioned above, the oscilloscope will start sampling the signals. As it changes over time, it will be displayed on the screen. In case you do not see the complete signal on the LCD, you can tap on the ‘Auto Scale’ panel key to scale the waveform correctly.
- If you want further adjust how the signal is being displayed, you can adjust the horizontal and vertical knobs. With the help of these knobs, you will be able to zoom in or out and shift the direction of the signal up/down/left/right. You need to ensure that the signal spans on the vertical scale for the best measurement.
- If you wish to calculate the voltage, you need to count the number of divisions and simply multiply it by the Volts/Division (or the vertical scale). You also need to note that the number of the divisions on the Y-axis to calculate the signal’s voltage with the help of these labels.
How to calculate the frequency from an oscilloscope?
First, you have to measure the time on the oscilloscope’s horizontal scale, as well as count the total horizontal divisions from one wave end to another.
Next, all you have to do is multiply the total number of horizontal divisions by the division/time to find the period of the signal. Then, you can perform the calculation to determine the frequency – dividing it by the period.
How to use an oscilloscope – FinalWord
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