Oscilloscopes are machines that measure and show voltage signals over a period of time. They are used to monitor the changes in an electric signal over time.
Voltmeters, also known as voltage meters, are used to measure the potential difference between two points in an electronic circuit. Now, you might be thinking, can we use an oscilloscope as a voltmeter?
Well, if your oscilloscope is a Cathode Ray Oscilloscope (CRO), then the answer to this is yes, it can be used to measure potential differences between two points just like a voltmeter. But there are some factors you should be considering if you plan to do that. They are discussed below.
Factors for Consideration
Nowadays, Digital Storage Oscilloscopes (DSO) are more widely used and popular compared to Cathode Ray Oscilloscopes (CRO). DSOs are the digitalized versions that offer more functions and are more preferable over CROs. So chances are even if you do own an oscilloscope, it is a DSO rather than a CRO.
CROs are generally more precise with an almost infinite input resistance; thus, they can be used as voltmeters. However, DSOs are simpler and more adequate to use unless you need to see the waveform, which in the case of measuring the potential difference between two electric points, is important.
Moreover, using CROs as a voltmeter is not very practical, and it is easier to just use a digital voltmeter instead. The only reason a CRO might be used as a voltmeter is as an experiment for students to get acquainted with the device and learn the basics of how it works. In the next section, I will briefly explain how to that.
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Procedure for a Simple Classroom Test
Note that we will be using a voltmeter as well in order to check validity since this is only a practice test. You will need the following things –
The steps for the procedure are as follows:
Step 1: Setting up
Set up the oscilloscope with the gain as 1 volt per division; set the time-base off and switch to DC on the AC/DC switch.
Step 2: Connecting
Connect the CRO’s input across one of the cells and adjust the gain to make the deflection one division on the graticule. After that, connect the voltmeter in parallel to the oscilloscope across the cell.
Step 3: Testing
Now, connect across two cells & then across three cells and test the deflection on the oscillator’s screen. After you are done observing, do the same thing again but reverse the leads beforehand to observe the deflection across the three cells in the opposite direction. The CRO will act as a voltmeter here.
Step 4: Retesting
Disconnect the cells and reconnect after changing the output of the power to 2 volts. Do the same thing with 4 volts and 6 volts as well. In all of these observations, the CRO will act as a voltmeter; this will help you better understand the CRO and how it works.
Step 5: Final Results
Switch on the time-base of the CRO (1 ms per division) to show the trace spread out on the screen. This will show whether the power supply provides a steady voltage or not, which is the result of your experiment.
That’s all, folks! The experiment ends here. I hope you were successful in using a CRO as a voltmeter. I hope you got the answer you were searching for. Thanks for reading.