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Have you ever been in a situation where you need to troubleshoot an electric circuit that needs more details than a conventional multimeter can provide? If you need to take measurements of things that are likely to change over time, such as voltage, amplitude, frequency, noise, etc., you need an oscilloscope!
An oscilloscope is a piece of useful equipment for checking rapid changes in voltage over a given time. Usually, when you measure voltage using an oscilloscope, you will see a line running from end to end on its screen. This line represents a graph of voltage measurement (y-axis) against time (x-axis).
This equipment comes in two versions: digital and analogue. Both versions have similar control buttons. However, digital oscilloscopes often have some hidden controls in an onscreen menu. This article shows you how to use an oscilloscope to measure DC voltage, regular voltage, high voltage, AC voltage, and frequency. Keep reading to find out more.
Why Oscilloscope Instead of the Voltmeter?
Although a voltmeter has an analogue display, it is somehow difficult to pinpoint the precise voltage measurement at short intervals; it’s quite hard to monitor a device’s voltage using a voltmeter.
Contrary, an oscilloscope has a digital display. It shows instantaneous voltage measurement per second. Furthermore, these voltage responses are displayed in a graphical representation, making it relatively easy to read, find, or follow a trend.
Some oscilloscopes have multiple channels that allow you to connect more than one device simultaneously and compare their voltage readings.
Can You Measure Voltage With an Oscilloscope?
The answer is YES! The oscilloscope is predominantly a voltage measuring device. Voltage is the measure of electric potential between two terminals in a circuit, usually expressed in volts.
You can measure voltage with an oscilloscope by manually counting the number of waveform scope dissections on the vertical scale. This is the basic technique of measuring voltage using an oscilloscope.
How to Use Oscilloscope to Measure Dc Voltage
While oscilloscopes measure voltage by multiplying the number of volts per dissection by the number of vertical reticules, measuring direct current (DC) involves a lengthy procedure depending on the type of scope you have.
Below is a step-by-step procedure of how to use an oscilloscope to measure DC Voltage:
- Step 1: Power on your oscilloscope.
- Step 2: On the front panel menu selection, select [AUTO].
- Step 3: On the horizontal section of the front panel, set the [MAIN TIME/DIV] knob to 0.1mS.
- Step 4: On the vertical section of the front panel, there are switches labeled [CH1, CH2, DUAL ADD]. Select [DUAL].
- Step 5: Around [CH1], there are additional switches [AC, GND, DC]. Select [DC].
- Step 6: Turn [CH1 VOLT] knob to 1V.
- Step 7: Adjust the position of the [CH1] knob so that the trace is aligned at the bottom of the grid. The bottom is the zero point of [CH1].
- Step 8: Repeat steps 6 & 7 for [CH2].
- Step 9: Locate the switches on your oscilloscope’s probe, then adjust them to x1.
- Step 10: Connect the clips onto your electric circuit.
- Step 11: Connect the probe to the point you want to measure the voltage on your circuit.
- Step 12: Measure the fluctuations from your oscilloscope voltage displayed on the screen.
How to Use Oscilloscope to Measure Voltage
An oscilloscope gives you a visual display of an electronic signal in a voltage against a time graph called a “waveform.” The waveform is created by connecting a given signal on a DUT (device under test) to your oscilloscope using a probe. The grounding clip is connected to a grounding point, and the probe tip is connected to a signal point. Using your oscilloscope to measure voltage provides basic details about the signal. However, this equipment offers more sophisticated tools for analyzing the signal further.
Here is a step-by-step process of how to measure voltage with an oscilloscope:
- Step 1: Power on your oscilloscope and set it to default by pressing the [Default Setup] button on the front panel key.
- Step 2: Plug in the probe into channel one of your oscilloscope.
- Step 3: Locate a reliable/stable grounding point and attach the ground clip.
- Step 4: Connect the probe’s tip to the signal you want to measure.
- Step 5: At this stage, your oscilloscope tests the voltage of your signal and displays it as it changes with time. Press [Auto Scale] to scale and center your waveform if your oscilloscope screen does not show a complete signal.
- Step 6: Use the horizontal and vertical knobs to select how signals are displayed on the screen. These knobs help shift signals up, down, left or right, and zoom in or out.
Note: For accurate oscilloscope voltage measurement, ensure your signal spans on most of the vertical scale.
- Step 7: The most common method to calculate signal voltage is to count the number of waveform divisions from top to bottom and then multiply by the vertical scale.
How Does an Oscilloscope Measure High Voltage?
Suppose you want to measure high-voltage using your oscilloscope; you need to have a high-voltage probe. This probe usually has a long-shielded handle with a voltage separator. It scales down high voltage signals by a 1000 factor, allowing up to 40,000 volts measurements.
Here is how to measure high voltage using an oscilloscope:
- Step 1: Turn on your oscilloscope.
- Step 2: Plug in the high voltage probe into channel 1 [CH1] of your oscilloscope.
- Step 3: Connect the probe’s ground crocodile clip to a reliable grounding point.
- Step 4: Adjust the scope’s vertical sensitivity to 1v/division.
- Step 5: Set the vertical scale to match the zero point on your oscilloscope display.
- Step 6: Adjust the scope’s horizontal sweep rate to a suitable high voltage time scale.
- Step 7: Hold the high voltage probe by the shielded handle and connect it to the high voltage signal you want to measure.
- Step 8: Read the waveform on the scope’s screen and count the number of vertical dissections above the centerline. Multiply the number by 1v/division. Multiply the result by 1000 to get the actual reading scaled by the high voltage probe.
How Can the Oscilloscope Be Used to Measure AC Voltage and Frequency?
Frequency is measured by examining the signal’s frequency spectrum on the oscilloscope screen and further making some calculations. Frequency is the number of cycles a waveform takes the upper second. Below is a step-by-step procedure of measuring frequency on an oscilloscope:
- Step 1: Increase sensitivity on the vertical scale to obtain a clear visual of the waveform. Make sure you do not cut off any of its amplitude.
- Step 2: Tune the sweep rate to allow your oscilloscope screen to display two full-waveform cycles.
- Step 3: Count the number of dissections of one full cycle from start to end.
- Step 4: Multiply the number of units you counted by the horizontal sweep rate. This gives you the time (in seconds) of the waves.
- Step 5: Now calculate the frequency in Hertz (number of cycles per second) using a period.
Oscilloscopes are handy equipment in the electrical field. Most scopes have additional features and measurement tools used to measure characteristics such as frequency, amplitude, voltage, etc. In other words, they measure voltage-based as well as time-based characteristics of a signal. If you are looking to buy an oscilloscope, consider one that goes beyond fundamental use (voltage measurement).
We hope you found this article informative, and you can now use your oscilloscope to measure DC and AC voltage, high voltage and frequency. Remember to observe safety guidelines when dealing with high voltage signals.