How to Measure Voltage with an Oscilloscope (Full Guide)
How to use an oscilloscope to measure voltage?
Measuring voltage is a crucial skill when working with electronic circuits, and an oscilloscope is one of the best tools for this task.
Unlike a simple multimeter that only gives you a number, an oscilloscope shows you a detailed picture of how the voltage changes over time.
There are many ways to measure voltage using an oscilloscope and it depends on the type of signal.
In this post, we will walk you through the steps to measure voltage using an oscilloscope, making it easy for beginners to get accurate and insightful readings.
AC Voltage (Sinusoidal)
You can measure a steady alternating voltage with a multimeter by setting it to AC.
The polarity of the contacts doesn’t matter because the current flows back and forth.
The multimeter shows the RMS value, which is the average value of the sine wave.
To find the peak value (from minimum to maximum), multiply the RMS value by 1.41 (the square root of 2).
For accurate readings, the signal should be regular.
If the AC voltage has an unknown or different shape (like a triangle or rectangle), you should use an oscilloscope instead.
DC Voltage
To measure DC voltage with a multimeter, set it to “DC” mode.
Connect the black cable to the negative terminal and the red cable to the positive terminal.
The multimeter will show the DC voltage on its display.
Make sure to choose the right voltage range on the multimeter.
Set the dial to a value higher than the maximum voltage you expect to measure.
Measuring Voltage with an Oscilloscope
An oscilloscope can measure any type of waveform.
To do this, you connect the signal to a measurement channel, choose the trigger, and set the time base and voltage range.
It doesn’t matter if the signal is a sine wave, triangle wave, or any other shape; the oscilloscope can handle it.
How does an oscilloscope measure voltage?
Inside an oscilloscope, a circuit is connected through a resistor. The value of this resistor depends on the type of oscilloscope.
It can be 50 Ohms for high-frequency measurements or a megohm for other cases.
The oscilloscope shows the voltage drop across the resistor, similar to how a multimeter works.
This means that measuring can affect the circuit being tested, especially if the oscilloscope or multimeter draws a lot of current. To reduce this effect, active probes may be needed.
An oscilloscope probe is used in circuit simulators to measure voltage. The image shows a simulation of an LED strip. In these simulators, symbolic probes are used to sample the simulated voltage.