This instruction is only for students who have basic knowledge of building analog circuits and want to use Oscilloscopes to do some further analysis. It may cost you 30 to 60 minutes to finish all the steps.
Before you start
This instruction is for DSO-X 2024A Digital Storage Oscilloscope which is made by Agilent Technologies. The device is used to observe or measure signals for a built circuit usually on breadboard.
Oscilloscopes require “probes”(Figure 1)to obtain signals.
There are four input channels and one output channel on the device. In labs only input channels are used for measurement.
Function area(A), operation area(B), screen area(C) and port area(D) are shown in the figure(Figure 2).
Step 1: How to Measure a Simple Voltage Signal
Warning! : you should follow the lab safety rules when using electrical devices to avoid electric shock.
How to Measure a Simple Voltage Signal
1 Turn on the power.
2 Connect the probe with the Oscilloscope input channel 1(slightly rotate the joint until it perfectly connects with the input port).(Figure 3)
3 Connect the pin(1) on the probe to the positive side of the resistor (or any component that you are asked to measure). Then connect the ground(2) of the probe to the common ground in your circuit.(Figure 4)
4 Click the “Auto Scale” button on the upper right corner of the function area.(Figure 5)Now you should see a sine wave signal on the screen area(Figure 6)
Step 2: How to Use “Meas” Function
Basic Functions in Oscilloscope
Now you have get a signal on the screen and you want to do some further analyze on it.
The “Meas” function is the common function that is used most frequently on Oscilloscopes. The button is in the middle of function area. After observing your first signal on the Oscilloscope, you can use the “Meas” function to analyze the properties of the signal you get. There are so many different types of measurement you can do by using Meas function, and generally you will use DC, AC full screen, frequency and phase in your future lab
How to use “Meas” function
1 Click “Meas”.(Figure 7)
2 In the operation area, find the “Source” and click the button below to choose the right channel you want to analyze.(Figure 8)
The select button(Figure 9): when you click an operation button, a green clockwise arrow appears on the upper left corner of the operational item, then you can rotate the select button in left side of the function area to find your choice faster.
3 In the operation area, find “Type”, click the button below to choose the type of measurement you want to do on the signal. Then click the button below “Add Measurement” to add the data on the screen. Now you should observe the frequency for your signal. (Figure10)(You can add more than one measurement on the same signal by repeating step3!)
4 You might want to use “Setting” in operation area to change the relations between different channels to do a specific measurement. When you click the button you will see a lower menu and you can click “Back” button on the left of the operation area to return the upper menu.(Figure 11)
5 Click “Clear Meas” button to clear the past measurement, the operation is similar with step3.(Figure 12)
Step 3: How to Use Math Function
Math function is only used to analyze multiple signals(see more details in next part) When you are use Oscilloscopes to measure different signals in you series connected circuit, you will get a “Ground issue“. Which means you cannot measure all signals together by simply connecting your probes with components. To get accurate signal graphs, we use math function to overcome ground issue.
How to use Math function
1 Assume you are already get two signals on screen, channel one is power source, and channel two is the component shares ground with power.(Figure 13)
2 Click “Math” button in the right of function area.(Figure 14)
3 In the operation area, choose the “function” f(t) and then choose the ”–“operator so f(t)=Ch1-Ch2. And on the “Source 1” and “Source 2” you can determine which two channels you want to do the math function.(Figure 15)
4 Now you should see a purple signal on screen which is your component that does not shares ground with power source. Then you can use Meas function to observe its properties.(Figure 16)
Step 4: How to Measure Multiple Signals
Ground issue(Figure 17)
The most common issue for multiple signals measurement is ground issue. Oscilloscope is a ground sensitive devices, it considers that input signals should back to the same ground, which means all four input channels share the same ground. So when measure more than one components in your circuit, you have to make sure all the probes have the same ground.
How to Measure multiple signals
1 Connect probes with input ports.(Figure 18)
2 Connect the pin of channel one to the positive side of power source, and the ground to the negative side of power source. Connect pin of channel two to the positive side of the component that have the same ground with power source. (trick of the ground issue: because all channels share the ground, you don’t need to connect the second probe’s ground)(Figure 19)
3 Click “Auto Scale”.(Figure 5)
4 Use math function (channel one – channel two) to obtain the signal from component that doesn’t share the ground with power source.(Figure 20)
Step 5: How to Use Cursors Function
How to use Cursors function
To analyze more details for your signals, cursors function is used to approach specific points on your signal waves
1 Click “Cursors” button above the “Meas” function.(Figure 21)
2 In the operation area, make sure you are in “Manual” Mode, then click the button below “Cursors” and choose “X1”(Figure 22)
3 In the function area, find the rotatable “Cursors” button. By rotating the button you are able to see a vertical dotted line on screen. Choose a point on your signal wave and use “X1” line to approach it. Now you can see the specific time on that point(Figure 21)
4 Repeat step 2 and step 3 to get Y1, X2,Y2. Your “Y” lines should be horizontal dotted line that meet at the same point with “X” lines, so X1 and Y1 should be the same point, X2 and Y2 should be another point. And the “Y” represent the specific voltage on the point.(Figure 23)
By observing the Cursors the voltage and time difference between two points on the signal wave can be find. The function can also be used to compare the voltage difference between two (or more) signals at the same time or the time difference between two (or more) signals when they have the same voltage level.
Step 6: Observe Graphs
When an Oscilloscope is used to do measurement, “Auto scale” is used to generate signals. However, the graphs on the screen sometimes is not good to observe and analyze. So Oscilloscopes provide some scaling buttons for users to get better signals on screen.
There are “horizontal” and “Vertical” function that allowed you to change the size of the waveform on screen. To do this, first click the button under green channel button, then by rotating the button waveform can be moved up and down.(Figure 24)
To change the amplitude level, click the vertical button above the channels and rotate it.(Figure 24)(Figure 25)
To change the time period level, click the horizontal button and rotate it.(Figure 26)(Figure 27)
Now you should know how to use oscilloscope to achieve some simple tasks, and by combating these functions together you can even do some complex analysis with your circuit. If you avoid any ground issue during your measurement , all the signals you got should be precise enough for academic usage.